Glass cloth, prepreg and printed wiring board

Abstract

Provided is a glass cloth woven with glass yarns containing a plurality of glass filaments as warp and weft, wherein the surface of the glass cloth is treated with a surface treatment agent, and the difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent measured using a split cylindrical resonator at 10 GHz exceeds 0 and is 1.0×10 ‑3 the following.

Description

Technical Field

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

[0002] The advancement of high-performance information devices such as smartphones and high-speed communications, typified by 5G communications, has led to a significant shift in the dielectric constant and dielectric loss tangent of insulating materials used in printed wiring boards for high-speed communications to reduce transmission losses. Furthermore, higher levels of insulation reliability are required than ever before.

[0003] Patent documents 1 and 2 report examples of insulating materials for printed wiring boards for high-speed communications. Specifically, it is known that by utilizing vinyl or methacryloyloxy groups, a free radical reaction of terminal-modified polyphenylene ether, etc. is crosslinked and cured to obtain a low-dielectric thermosetting resin (hereinafter referred to as "matrix resin"), the low-dielectric thermosetting resin is impregnated with glass cloth and dried to obtain a prepreg, the prepreg is laminated and heated and pressurized to cure the laminate (patent documents 1 and 2). According to patent documents 1 and 2, by combining with glass cloth having a low dielectric constant and a low dielectric loss tangent, a low dielectric constant and a low dielectric loss tangent as a laminate are exhibited.

[0004] To improve reactivity with low-dielectric resins that cure via free radical reactions, silane coupling agents with relatively high hydrophobicity and containing functional groups such as methacryloyl that participate in free radical reactions are used as surface treatment agents for glass cloth surfaces. However, the use of these silane coupling agents as surface treatments can lead to reduced insulation reliability due to delamination at the glass cloth / resin interface. As a solution to this problem, a method for eliminating the presence of surfactants on the glass cloth surface has been disclosed (Patent Document 3).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2019 / 065940

[0008] Patent Document 2: International Publication No. 2019 / 065941

[0009] Patent Document 3: International Publication No. 2020 / 194772 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] However, even though Patent Document 3 assumes that delamination at the glass cloth / resin interface during drilling can be suppressed, it fails to address the increased heat generation associated with increased densification of chassis wiring and high-speed communications, and the resulting reduction in insulation reliability caused by this delamination. Therefore, there is room for improvement. Therefore, the present invention aims to provide a glass cloth exhibiting excellent heat resistance, a prepreg using the same, and a printed wiring board.

[0012] Solutions for solving problems

[0013] The present inventors have conducted in-depth research and have focused on the organic matter physically attached to the glass cloth. Specifically, the present inventors have found that by reducing the very small amount of modified sizing agents that cannot be reduced by thermal cleaning and the modified silane coupling agents that cannot form a chemical bond with the glass surface to below a certain amount, the heat resistance of the laminate can be significantly improved. In addition, the present inventors have found that the modified sizing agents cannot be fully reduced using known conditions; the silane coupling agents that cannot form a chemical bond with the glass surface cannot be fully reduced by washing with water as a known method due to their strong hydrophobicity. Furthermore, the present inventors have found that the residue of the above-mentioned attached organic matter can be compared by the difference between the dielectric loss tangent of a specific glass cloth and the dielectric loss tangent of the bulk phase. Based on the above findings, the present invention has been completed. A part of the present invention is illustrated below. [1]

[0015] A glass cloth is woven by weaving glass yarns containing a plurality of glass filaments as warp and weft, wherein the surface of the glass cloth is treated with a surface treatment agent, and the difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent measured using a split cylindrical resonator at 10 GHz exceeds 0 and is 1.0×10 -3 the following. [2]

[0017] The glass cloth according to item 1, wherein the difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent is 8.0×10 -4 the following. [3]

[0019] The glass cloth according to item 2, wherein the difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent is 6.0×10 -4 the following. [4]

[0021] The glass cloth according to item 3, wherein the difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent is 4.0×10 -4 the following. [5]

[0023] The glass cloth according to item 4, wherein the difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent is 2.0×10 -4 the following. [6]

[0025] The glass cloth according to any one of items 1 to 5, wherein the glass yarns constituting the glass cloth have a silicon (Si) content of 95% by mass to 100% by mass in terms of silicon dioxide (SiO 2 ). [7]

[0027] The glass cloth according to any one of items 1 to 6, wherein the glass yarns constituting the glass cloth have a Si content of 99.0% by mass to 100% by mass in terms of SiO 2 . [8]

[0029] The glass cloth according to any one of items 1 to 7, wherein the glass yarns constituting the glass cloth have a Si content of 99.9% by mass to 100% by mass in terms of SiO 2 . [9]

[0031] The glass cloth according to any one of items 1 to 8, wherein the bulk dielectric loss tangent of the glass constituting the glass yarn exceeds 0 at 10 GHz and is 2.5×10 -3 the following.

[10]

[0033] The glass cloth according to any one of items 1 to 9, wherein the surface treatment agent contains a silane coupling agent represented by the following general formula (1):

[0034] X(R) 3-n SiE n (1)

[0035] In formula (1), X is an organic functional group having at least one of an amino group and an unsaturated double bond group, wherein the unsaturated double bond group has free radical reactivity, Y is each independently an alkoxy group, n is an integer of 1 to 3, and R is each independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.

[11]

[0037] The glass cloth according to item 10, wherein X in the general formula (1) is an organic functional group that does not form a salt with an ionic compound.

[12]

[0039] The glass cloth according to item 10 or 11, wherein X in the general formula (1) does not contain an amine or an ammonium cation.

[13]

[0041] The glass cloth according to any one of items 10 to 12, wherein X in the general formula (1) is an organic functional group having one or more methacryloxy groups or acryloxy groups.

[14]

[0043] The glass cloth according to item 9, wherein the bulk dielectric loss tangent of the glass constituting the glass yarn is 2.0×10 -3 the following.

[15]

[0045] The glass cloth according to item 14, wherein the bulk dielectric loss tangent of the glass constituting the glass yarn is 1.7×10 -3 the following.

[16]

[0047] The glass cloth according to item 15, wherein the bulk dielectric loss tangent of the glass constituting the glass yarn is 1.5×10 -3 the following.

[17]

[0049] The glass cloth according to item 16, wherein the bulk dielectric loss tangent of the glass constituting the glass yarn is 1.2×10 -3 the following.

[18]

[0051] The glass cloth according to item 17, wherein the bulk dielectric loss tangent of the glass constituting the glass yarn is 1.0×10 -3 the following.

[19]

[0053] The glass cloth according to any one of items 1 to 18, wherein the total carbon content of the glass cloth is 0.02% to 0.5%.

[20]

[0055] The glass cloth according to any one of items 1 to 19, wherein the total carbon content of the glass cloth is 0.02% to 0.1%. [twenty one]

[0057] The glass cloth according to any one of items 1 to 20, which is used for a printed wiring board base material. [twenty two]

[0059] A prepreg comprising the glass cloth according to any one of items 1 to 21, a thermosetting resin, and an inorganic filler. [twenty three]

[0061] A printed wiring board comprising the prepreg according to item 22.

[0062] Effects of the Invention

[0063] According to the present invention, it is possible to provide a glass cloth exhibiting excellent heat resistance, a prepreg using the same, and a printed wiring board. DETAILED DESCRIPTION

[0064] An embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described in detail below, but the present invention is not limited thereto and various modifications can be made without departing from the spirit and scope of the present invention.

[0065] In the present embodiment, the numerical range recorded using "~" includes the numerical values ​​before and after "~" in its numerical range. In addition, in the present embodiment, within the numerical range recorded in stages, the upper limit value or lower limit value recorded in a certain numerical range can be replaced with the upper limit value or lower limit value of the numerical range recorded in other stages. Furthermore, in the present embodiment, the upper limit value or lower limit value recorded in a certain numerical range can also be replaced with the value shown in the embodiment. And in the present embodiment, the term "process" not only includes an independent process, but also includes this term if the purpose of the process is achieved even if it cannot be clearly distinguished from other processes.

[0066] [Glass cloth]

[0067] The glass cloth of this embodiment is a glass cloth woven with glass yarns containing a plurality of glass filaments as warp and weft. The glass cloth of this embodiment is surface treated with a surface treatment agent, and the difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent measured using a split cylindrical resonator at 10 GHz exceeds 0 and is 1.0×10 -3 Below (e.g. 1.00×10 -3 The glass cloth of this embodiment is preferably used as a printed wiring board substrate. The surface treatment agent is used to treat the surface of the glass yarn (including the glass filaments) as described below.

[0068] [Difference between dielectric loss tangent of glass cloth and bulk dielectric loss tangent]

[0069] The technical features that achieve the above-described effects of the glass cloth of the present embodiment are specified by satisfying the following relationship:

[0070] |Glass cloth dielectric loss tangent - bulk dielectric loss tangent|@10GHz≤1.0×10 -3 .

[0071] The dielectric loss tangent of the glass cloth at 10 GHz and the bulk dielectric loss tangent at 10 GHz can be measured using a split cylindrical resonator as described later. Specific measurement methods and measurement conditions are described in Examples.

[0072] From the perspective of further improving the effect of the present invention, the dielectric loss tangent and bulk dielectric loss tangent of the glass cloth are in a state that satisfies the dielectric loss tangent of the glass cloth - bulk dielectric loss tangent @ 10 GHz ≤ 1.0 × 10 -3 And it is preferably in a state that satisfies 0≤glass cloth dielectric loss tangent-bulk dielectric loss tangent@10GHz≤0.8×10 -3 The relationship between the dielectric loss tangent of glass cloth and bulk dielectric loss tangent of glass cloth is preferably 0≤0.6×10 -3 The relationship between the dielectric loss tangent of glass cloth and the bulk dielectric loss tangent of glass cloth@10GHz≤0.4×10 -3 The relationship between the dielectric loss tangent of glass cloth and bulk dielectric loss tangent of glass cloth is particularly preferred to be 0≤0.2×10 -3 relationship.

[0073] [Measurement method of dielectric loss tangent of glass cloth]

[0074] The dielectric property evaluation method of the present embodiment includes a process for measuring the dielectric properties of glass cloth (hereinafter also referred to as cloth) using a split cylindrical resonator and a resonance method. If the measurement method in the above-mentioned measurement process is a measurement method using a split cylindrical resonator and a resonance method, it is not limited to a specific method. According to this measurement method, compared with the previous measurement method of evaluating the dielectric properties by making a substrate as a measurement sample, it can be measured simply and accurately. The reason why the dielectric properties of the cloth can be measured simply and accurately by using the resonance method is not limited by theory, but is because the resonance method is suitable for evaluating low-loss materials in the high-frequency region. As dielectric property evaluation methods other than the resonance method, the lumped constant method and the reflection transmission method are known. For the lumped constant method, since it is necessary to use two electrodes to clamp the measurement sample to form a capacitor, there is a problem that the operation is very complicated. In addition, for the reflection transmission method, when evaluating low-loss materials, the influence of the matching characteristics of the port is strongly manifested, and there is a problem that it is difficult to evaluate the dielectric loss tangent of the sample with high accuracy. Therefore, the evaluation method of the dielectric properties of the cloth is preferably the resonance method.

[0075] In this measurement step, a split cylindrical resonator can be cited as a preferred measuring instrument using the resonance method.

[0076] In order to measure the dielectric properties of the above-mentioned cloth used for high-speed communication printed wiring boards, the measurable range of the measuring instrument is preferably Dk = 1.1 Fm for both the dielectric constant (Dk) and the dielectric loss tangent (Df). -1 ~50Fm -1 , Df=1.0×10 -6 ~1.0×10 -1 The range of Dk=1.5Fm is more preferable. -1 ~10Fm -1 , Df=1.0×10 -5 ~5.0×10 -1 The range of Dk=2.0Fm is more preferable. -1 ~5Fm -1 , Df=5.0×10 -5 ~1.0×10 -2 within the range.

[0077] The measurable frequency of the measuring instrument is preferably 10 GHz or higher. If the frequency is 10 GHz or higher, it is possible to evaluate the characteristics of the glass cloth in a frequency band assumed when it is actually used as a substrate for a printed wiring board for high-speed communication.

[0078] In order to measure the dielectric properties of the cloth over a larger area and determine whether the measurement result is within the range of the preset reference value, the measurement area of ​​this measurement method is preferably 10 mm 2 The measurement area of ​​this measurement method is more preferably 15mm 2 More than 20 mm, more preferably 2 above.

[0079] The thickness of the sample that can be measured is not particularly limited, but is preferably 3 μm to 300 μm, more preferably 5 μm to 200 μm, and even more preferably 7 μm to 150 μm.

[0080] [Bulk dielectric loss tangent]

[0081] In this specification, the bulk dielectric loss tangent refers to the dielectric loss tangent of the glass cloth raw material measured at 10 GHz using a split cylindrical resonator. As described below, the glass cloth raw material can include glass types, glass filaments, glass yarns, and other glass raw materials. The bulk dielectric loss tangent of the glass raw material constituting the glass cloth can be measured using the same method used to measure the dielectric loss tangent of the glass cloth using a glass plate with a thickness of 300 μm or less and of the same type and composition as the glass raw material.

[0082] From the viewpoint of further improving the effects of the present invention, the bulk dielectric loss tangent of the glass constituting the glass yarns in the weaving of the glass cloth of this embodiment is preferably 2.5×10 -3 less than 2.0×10 -3 Below, more preferably 1.7×10 -3 Below, more preferably 1.5×10 -3 Below, particularly preferably 1.2×10 -3 Below, most preferably 1.0×10 -3 the following.

[0083] Although not wishing to be bound by theory, the dielectric loss tangent, bulk dielectric loss tangent, and the difference between the dielectric loss tangent and bulk dielectric loss tangent of the glass cloth and their difference are considered to be adjusted to the above-mentioned numerical range by, for example, selecting a surface treatment agent in a manner that suppresses the residue and generation of the following (i) or (ii); optimizing the conditions of the heating degreasing (heating desizing) step, the residual sizing reduction step, the fixing step, the washing step, the drying step, the fine washing step, and the fine drying step in the glass cloth manufacturing process; and washing the surface-treated glass cloth with an organic solvent in the fine washing step.

[0084] (i) Generation of thermally oxidized degradation products of the sizing agent physically attached to the surface of the glass fibers

[0085] (ii) Residues or modified products of the surface treatment agent that do not form a chemical bond with the glass surface but are physically attached and cannot be removed by washing with water

[0086] [Average filament diameter]

[0087] The average filament diameter of the glass filaments is preferably 2.5 to 9.0 μm, more preferably 2.5 to 7.5 μm, further preferably 3.5 to 7.0 μm, further preferably 3.5 to 6.0 μm, and particularly preferably 3.5 to 5.0 μm.

[0088] [Beating density]

[0089] The beating density of the warp and weft yarns 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.

[0090] [Cloth weight]

[0091] In addition, the cloth weight (weight per unit area) of the glass cloth is preferably 8 to 250 g / m 2 , more preferably 8 to 100 g / m 2 , more preferably 8 to 80 g / m 2, particularly preferably 8 to 50 g / m 2 .

[0092] [Weaving structure]

[0093] The weave structure of the glass cloth is not particularly limited, and examples thereof include plain weave, basket weave, satin weave, and twill weave. Among them, a plain weave structure is more preferred.

[0094] [Glass Type]

[0095] The glass cloth used in the laminate uses the glass that is commonly referred to as E glass (alkali-free glass). On the other hand, in the glass cloth of the present embodiment, for example, L glass, NE glass, D glass, L2 glass, T glass, silica glass, quartz glass etc. can be used. From the viewpoint of dielectric properties, it is more preferred to use L glass, L2 glass, silica glass, quartz glass etc., wherein silica glass, quartz glass are particularly preferably used. In addition, from the viewpoint of improving the dimensional stability of the laminate substrate containing glass cloth, it is more preferred to use S glass, T glass, silica glass, quartz glass, wherein silica glass, quartz glass are particularly preferably used.

[0096] The Si content of the glass yarns constituting silica glass and quartz glass cloth, calculated as SiO2, is preferably in the range of 95% to 100% by mass, more preferably 99.0% to 100% by mass, even more preferably 99.5% to 100% by mass, and particularly preferably 99.9% to 100% by mass. If the Si content is less than 95%, the dielectric properties and dimensional stability of the laminated substrate may be impaired.

[0097] Furthermore, the composition of each glass and the bulk dielectric loss tangent show the following relationship.

[0098] Glass with 99% by mass or more SiO2: Bulk dielectric loss tangent ≤ 1.2×10 -3 ;

[0099] Glass with a bulk dielectric loss tangent of 50% or more calculated as SiO2, 20% or more calculated as boron dioxide (B2O3), or 3% or more calculated as phosphorus pentoxide (P2O5): Bulk dielectric loss tangent ≤ 1.7×10 -3 ;

[0100] Glass containing 50% or more of SiO2, 20% or more of B2O3, or 0.4% or more of strontium oxide (SrO): Bulk dielectric loss tangent ≤ 1.7×10 -3

[0101] [Glass fiber and silane coupling agent]

[0102] The glass fibers (including glass filaments) constituting the glass cloth are preferably surface-treated with a silane coupling agent. As the silane coupling agent, for example, the following general formula (1) is preferably used:

[0103] X(R) 3-n SiE n (1)

[0104] (In formula (1), X is an organic functional group having at least one of an unsaturated double bond group and an amino group, the unsaturated double bond group having free radical reactivity such as a carbon-carbon double bond having free radical reactivity, Y is each independently an alkoxy group, n is an integer of 1 to 3, and R is a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group)

[0105] Silane coupling agent shown.

[0106] This embodiment focuses on the reasons why the dielectric loss tangent of glass cloth has been increased in the past:

[0107] (i) a very small amount of thermally oxidized degraded products of the sizing agent remaining in a state physically attached to the surface of the glass yarn, and

[0108] (ii) Residues or modified products of the surface treatment agent that do not form a chemical bond with the glass surface but are physically attached and cannot be removed by washing with water.

[0109] From the perspective of suppressing the generation of (i) thermal oxidative degradation products or (ii) residues or modified products, X in the general formula (1) is preferably an organic functional group that does not form a salt with an ionic compound. Furthermore, from the perspective of reactivity with the matrix resin, X in the general formula (1) is more preferably an organic functional group having one or more methacryloyloxy groups or acryloyloxy groups. It should be noted that from the perspective of easily exhibiting the effects of the present invention, X in the general formula (1) preferably does not contain amines such as primary, secondary, and tertiary amines, or ammonium cations such as quaternary ammonium cations.

[0110] As for Y in the general formula (1), any form of alkoxy group may be used, but an alkoxy group having 1 to 5 carbon atoms (1, 2, 3, 4 or 5 carbon atoms) is preferred for stabilizing the treatment of glass cloth.

[0111] As the surface treatment agent, the silane coupling agent represented by the general formula (1) may be used alone or in combination with two or more silane coupling agents having different Xs in the general formula (1). As the silane coupling agent represented by the general formula (1), for example, known silane coupling agents such as vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, and 5-hexenyltrimethoxysilane may be used alone or in the form of a mixture thereof.

[0112] The molecular weight of the silane coupling agent is preferably 100 to 600, more preferably 150 to 500, and even more preferably 200 to 450. Among these, it is particularly preferred to use two or more silane coupling agents having different molecular weights. By treating the glass filament surface with two or more silane coupling agents having different molecular weights, the density of the treating agent on the glass surface increases, which tends to further improve reactivity with the matrix resin.

[0113] From the perspective of not hindering reactivity with the resin, the silane coupling agent is preferably nonionic. Among nonionic silane coupling agents, those containing at least one group selected from the group consisting of vinyl, methacryloxy, and acryloxy groups are preferred, with those containing at least one methacryloxy or acryloxy group being particularly preferred. By not hindering reactivity with the resin, the heat resistance and reliability of the printed wiring board can be improved.

[0114] In formula (1), X is an organic functional group having at least one of the unsaturated double bond group and the amino group. Therefore, not only the embodiment in which X has both the unsaturated double bond group and the amino group, but also the embodiment in which X has the unsaturated double bond group but does not have the amino group, and the embodiment in which X does not have the unsaturated double bond group but has the amino group are all included in the scope of formula (1).

[0115] [Method for manufacturing glass cloth]

[0116] The method for producing the glass cloth of the present embodiment is not particularly limited, and examples thereof include a method including the following steps:

[0117] A heating and desizing process of heating the glass cloth at a temperature of 650°C to 1000°C to remove the sizing;

[0118] A covering step of attaching a silane coupling agent to the surface of the glass filament using a treatment liquid having a concentration of 0.1 to 3.0 wt%;

[0119] A fixing step of fixing the silane coupling agent to the surface of the glass filament by heating and drying;

[0120] A washing step of washing the silane coupling agent that has not formed a chemical bond with the surface of the glass filament with water;

[0121] A drying step of heating and drying the washed glass cloth; and

[0122] This is a fine washing process to reduce the residues and modified products of the silane coupling agent that cannot be reduced by water and do not form a chemical bond with the surface of the glass filaments.

[0123] Furthermore, the covering, fixing, washing, and fine washing steps can be performed on the glass filaments before the weaving step to produce the glass cloth, or after the weaving step. The glass cloth manufacturing method may, if necessary, further include a residual size reduction step to reduce the amount of modified sizing agents remaining in the heat desizing step, and a fiber-opening step to open the glass filaments of the glass cloth after the weaving step. It should be noted that when the washing step is performed after the weaving step, the washing step can be performed concurrently with the fiber-opening step, using, for example, a high-pressure water spray. It should be noted that the composition of the glass cloth generally does not change before and after fiber-opening.

[0124] It is considered that after the attached organic matter that increases the dielectric loss tangent is removed by the above-mentioned production method, a silane coupling agent layer can be formed on the surface of each glass filament constituting the glass yarn.

[0125] Examples of residual slurry reduction processes include dry cleaning methods such as plasma irradiation and UV ozone; wet cleaning methods such as high-pressure water washing, organic solvent washing, nanobubble water washing, and ultrasonic water washing; and heating cleaning at a higher temperature than in the heat desizing process. These methods can also be combined. Among these, the residual slurry reduction process is preferably a short-term heating cleaning process in which the glass cloth is passed through a heating furnace at 800°C or above in a roll-to-roll manner.

[0126] In the coating step, the treatment liquid can be applied to the glass cloth by (1) immersing the glass cloth in a bath of the treatment liquid (hereinafter referred to as the "immersion method"), or (2) directly applying the treatment liquid to the glass cloth using a roll coater, die coater, or gravure coater. When applying by the immersion method (1), the immersion time of the glass cloth in the treatment liquid is preferably set to 0.5 seconds or more and 1 minute or less.

[0127] In addition, as a method of heating and drying the solvent after the treatment liquid is applied to the glass cloth, known methods such as hot air and electromagnetic waves can be mentioned.

[0128] The heating and drying temperature is preferably 80° C. or higher, more preferably 90° C. or higher, to allow the reaction between the silane coupling agent and the glass to proceed sufficiently. To prevent degradation of the organic functional groups of the silane coupling agent, the heating and drying temperature is preferably 300° C. or lower, more preferably 180° C. or lower.

[0129] The fine washing step is not particularly limited as long as it is a method that can reduce the residues and modified products of the silane coupling agent that cannot be reduced by water and that do not form chemical bonds with the surface of the glass filaments. Examples include washing with an organic solvent. By performing the fine washing step, even when using raw materials such as quartz glass, it is easy to adjust the difference between the dielectric loss tangent and the bulk dielectric loss tangent of the resulting glass cloth to within the numerical range described above.

[0130] In the fine washing step, in order to reduce the residues and modified products of the silane coupling agent that cannot be reduced by water, it is preferred to use a highly hydrophobic organic solvent or an organic solvent with a high affinity for the residues and modified products of the silane coupling agent having hydroxyl groups. The washing method can use a well-known method such as immersion method, spray spray, etc., and heating and cooling can be performed as needed. It is preferred to use a squeeze roller or the like to remove excess solvent from the washed glass cloth before fine drying in a manner that does not allow the dissolved attachments to adhere to the glass cloth. The organic solvent used is not particularly limited. For example, as a highly hydrophobic organic solvent, the following can be mentioned:

[0131] Saturated chain aliphatic hydrocarbons such as n-pentane, isopentane, n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, 2,2,4-trimethylpentane (isooctane), n-nonane, isononane, n-decane, isodecane, and 2,2,4,6,6-pentamethylheptane (isododecane);

[0132] Saturated cyclic aliphatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, and ethylcyclohexane;

[0133] Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, trimethylbenzene, and triethylbenzene;

[0134] Halogen-containing solvents such as chloroform, dichloromethane, and dichloroethane; etc.

[0135] Examples of organic solvents having high affinity with the modified silane coupling agent include:

[0136] Alcohols such as methanol, ethanol, butanol, etc.

[0137] Ketones such as acetone and methyl ethyl ketone;

[0138] Ethers such as methyl ethyl ether and diethyl ether;

[0139] N,N-dimethylformamide, N,N-dimethylacetamide and other amides;

[0140] Dimethyl sulfoxide; etc.

[0141] Among them, from the viewpoint of adjusting the difference between the dielectric loss tangent and the bulk dielectric loss tangent of the obtained glass cloth within the numerical range described above, aromatic hydrocarbons, alcohols, or ketones are preferred, and methanol is more preferred.

[0142] The glass cloth production method preferably includes a drying step to reduce the organic solvent after washing. To facilitate reduction of the organic solvent by drying, the organic solvent used in washing preferably has a boiling point of 120°C or lower. Drying of the organic solvent can be performed by known methods such as heat drying and air drying.

[0143] When heat drying is performed to reduce the organic solvent, known techniques can be used. However, from a safety perspective, hot air drying using low-pressure steam or heat medium oil as a heat source is preferred. The drying temperature is preferably above the boiling point of the washing solvent, and preferably below 180°C to suppress degradation of the silane coupling agent.

[0144] The fiber-opening method in the fiber-opening process is not particularly limited, and examples thereof include methods of fiber-opening the glass cloth using a water spray (high-pressure water fiber-opening), an oscillating washing machine, ultrasonic water, a mangle, and the like. During this fiber-opening process, there is a tendency to further reduce air permeability by reducing the tension applied to the glass cloth. It should be noted that to prevent the decrease in tensile strength of the glass cloth caused by fiber-opening, it is preferable to implement measures such as reducing friction of the contact members during weaving of the glass fibers, optimizing the sizing agent, and increasing adhesion.

[0145] The method for producing glass cloth may include an optional step after the fiber-opening step. The optional step is not particularly limited, and an example thereof includes a slitting step.

[0146] [Total carbon content of glass cloth]

[0147] In order to achieve good insulation reliability and reduce the amount of physically attached silane coupling agent, which should be reduced, the total carbon content of the glass cloth is preferably 0.02% to 0.5%, more preferably 0.022% to 0.20%, further preferably 0.023% to 0.10%, further preferably 0.024% to 0.08%, and particularly preferably 0.024% to 0.06%.

[0148] [Prepreg]

[0149] The prepreg of this embodiment contains at least the glass cloth and a matrix resin impregnated into the glass cloth, thereby providing a prepreg with few voids.

[0150] As the matrix resin, either a thermosetting resin or a thermoplastic resin can be used.

[0151] The thermosetting resin is not particularly limited, and examples thereof include:

[0152] a) An epoxy resin obtained by reacting and curing a compound having an epoxy group with a compound having at least one of an amino group, a phenol group, an acid anhydride group, a hydrazide group, an isocyanate group, a cyanate group, and a hydroxyl group that reacts with the epoxy group, either without a catalyst or with the addition of a catalyst having reaction catalytic ability such as an imidazole compound, a tertiary amine compound, a urea compound, or a phosphorus compound;

[0153] b) a radical polymerization type curable resin obtained by curing a compound having at least one of an allyl group, a methacryloyl group and an acryloyl group using a thermal decomposition type catalyst or a photodecomposition type catalyst as a reaction initiator;

[0154] c) a maleimide triazine resin obtained by reacting and curing a compound having a cyanate group and a compound having a maleimide group;

[0155] d) a thermosetting polyimide resin obtained by reacting and curing a maleimide compound and an amine compound;

[0156] e) Benzoxazine resins obtained by cross-linking and curing a compound having a benzoxazine ring by heat polymerization.

[0157] The thermoplastic resin is not particularly limited, and examples thereof include polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate, aromatic polyamide, polyetheretherketone, thermoplastic polyimide, insoluble polyimide, polyamideimide, and fluororesin.

[0158] In addition, in this embodiment, a thermosetting resin and a thermoplastic resin can be used in combination. Furthermore, the prepreg can contain an inorganic filler as needed. The inorganic filler is preferably used in combination with the thermosetting resin. Examples of the inorganic filler include aluminum hydroxide, zirconium oxide, calcium carbonate, aluminum oxide, mica, aluminum carbonate, magnesium silicate, aluminum silicate, silicon dioxide, talc, short glass fibers, aluminum borate, and silicon carbide.

[0159] [Printed wiring board]

[0160] The printed wiring board of this embodiment includes the above-mentioned prepreg, thereby providing a printed wiring board having excellent insulation reliability.

[0161] Example

[0162] The present invention will now be described in more detail using examples and comparative examples. The present invention is not limited to the following examples. Various evaluation methods are also described below.

[0163] [Method for measuring the thickness of glass cloth]

[0164] According to 7.10 of JIS R 3420, use a micrometer to gently touch the spindle parallel to the measuring surface while rotating it steadily. Read the scale after the ratchet clicks three times. Note that JIS R 3420 specifies general testing methods for products such as long glass fibers and glass cloth containing long glass fibers.

[0165] [Method for measuring weight per unit area (cloth weight)]

[0166] The weight per unit area of ​​the cloth is obtained by cutting the cloth into a predetermined size and dividing the weight by the sample area. 2 The dimensions of the glass cloth were measured and their weights were measured to determine the weight per unit area of ​​each glass cloth.

[0167] [Converted thickness]

[0168] Since the glass cloth is a discontinuous planar body containing air and glass, the converted thickness required for measurement by the resonance method is calculated by dividing the basis weight of each glass cloth by the density.

[0169] Conversion thickness (μm) = unit area weight (g / m 2 )÷density(g / cm 3 )

[0170] [Measurement method of dielectric loss tangent]

[0171] The dielectric loss tangent of each glass cloth is measured according to IEC 62562. Specifically, the glass cloth samples sampled with the size required for the measurement using each split cylindrical resonator are kept in a constant temperature and humidity oven at 23°C and 50% RH for more than 8 hours for humidity adjustment. Then, the dielectric properties are measured using a split cylindrical resonator (made by EM labs, Inc.) and an impedance analyzer (made by Agilent Technologies). The measurement is carried out 5 times for each sample, and the average value is calculated. In addition, the thickness of each sample is measured using the above-mentioned converted thickness. Similarly, a glass plate with a thickness of 300 μm or less of the same type and composition as the raw materials of each glass cloth is prepared, and the thickness value is obtained from the thickness measurement of the glass plate, and the bulk dielectric loss tangent is also determined from the thickness value. It mainly stipulates the method for measuring the dielectric properties in the microwave band of fine ceramic materials for dielectric substrates used in microwave circuits.

[0172] [Total carbon content of glass cloth]

[0173] The surface-treated glass cloth was heated at approximately 800°C for 1 minute, and the amount of carbon dioxide in the generated gas was measured using gas chromatography to determine the amount of carbon dioxide in the generated gas. The total carbon content per unit mass of the surface-treated glass cloth was determined by comparing the amount of carbon dioxide generated by heating a predetermined amount of acetanilide (C8H9NO) at approximately 800°C for 1 minute. This measurement was performed using a SUMIGRAPH NC-90A (manufactured by Sumika Chemical Analysis Service, Ltd.).

[0174] The molecular weight of acetanilide = 135.17

[0175] Carbon content of acetanilide = 71.09%

[0176] That is, the total carbon content of the glass cloth was calculated based on the following formula.

[0177] Total carbon content of glass cloth = [{mass of acetanilide×(carbon ratio of acetanilide / 100)} / peak area of ​​carbon dioxide generated from acetanilide]×{(peak area of ​​carbon dioxide generated from glass cloth / mass of glass cloth)×100}.

[0178] (Example 1)

[0179] Warp and weft yarns were made of glass fibers containing more than 99.9% SiO₂ by mass. Specifically, the warp yarns were made of silica glass with an average filament diameter of 5.0 μm, 100 filaments, and a twist of 1.0Z. The weft yarns were made of silica glass with an average filament diameter of 5.0 μm, 100 filaments, and a twist of 1.0Z. The glass cloth was then woven using an air-jet loom with a weft density of 66 warp yarns / 25 mm and 68 weft yarns / 25 mm. The resulting fabric was heat-treated at 800°C for 15 seconds to desize it. The glass cloth was then immersed in a treatment solution consisting of 0.9% 3-methacryloxypropyltrimethoxysilane (Z6030 (manufactured by DowToray Co., Ltd.) dispersed as a silane coupling agent in pure water adjusted to pH 3 with acetic acid. Next, after squeezing out the liquid, the glass cloth was heated and dried at 110°C for 1 minute to fix the silane coupling agent. The dried glass cloth was washed with water, dried at 110°C for 1 minute, and then immersed in methanol for a final wash to reduce the modified silane coupling agent that did not form a chemical bond with the surface of the glass filaments. After the final wash, the glass cloth was dried at 110°C for 1 minute to obtain glass cloth A with reduced physically attached modified silane coupling agent. After calculating the converted thickness from the unit area weight and density of glass cloth A, the dielectric loss tangent of glass cloth A was measured. It should be noted that the bulk dielectric loss tangent of glass is set to 0.00010.

[0180] (Example 2)

[0181] Glass cloth B was obtained in the same manner as in Example 1 except that the deoiling treatment was performed at 900°C for 15 seconds and the drying was performed at 110°C for 10 minutes. The dielectric loss tangent of the obtained glass cloth B was measured in the same manner as in Example 1.

[0182] (Example 3)

[0183] The same method as in Example 1 was used to obtain a glass cloth C in which the modified product of the physically attached silane coupling agent was reduced except that the heating drying time in the drying step was set to 15 minutes. The dielectric loss tangent of the obtained glass cloth C was measured in the same manner as in Example 1.

[0184] (Example 4)

[0185] Glass cloth D was obtained in the same manner as in Example 2, except that degreasing was performed by heating at 360°C for 48 hours and desizing was performed by heating at 1000°C for 15 seconds. The amount of modified products of physically attached silane coupling agents was reduced. The dielectric loss tangent of the obtained glass cloth D was measured using the same method as in Example 1.

[0186] (Example 5)

[0187] Warp and weft yarns were obtained using glass fibers with a composition range of SiO₂ = 40-50%, aluminum oxide (Al₂O₃) = 15-25%, boron tetroxide (P₂O₃) = 25-35%, and phosphorus tetroxide (P₂O₄) = 5-10%. Specifically, the warp yarns used were silica glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and a twist of 1.0Z. The weft yarns used were silica glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and a twist of 1.0Z. The glass cloth was woven using an air-jet loom with a weave density of 66 warp yarns / 25 mm and 68 weft yarns / 25 mm. The resulting fabric was heat-treated at 660°C for one hour and desized. Next, the glass cloth is immersed in a treatment liquid, which is a dispersion of 0.9% of 3-methacryloxypropyltrimethoxysilane as a silane coupling agent in pure water adjusted to pH = 3 using acetic acid; Z6030 (manufactured by Dow Toray Co., Ltd.). Then, after squeezing out the liquid, heat and dry it at 110°C for 1 minute to fix the silane coupling agent. The dried glass cloth is washed with water, dried at 110°C for 1 minute, and then further immersed in methanol for fine washing of the glass cloth to reduce the modified silane coupling agent that does not form a chemical bond with the surface of the glass filaments. After fine washing, it is dried at 110°C for 1 minute to obtain glass cloth E with reduced modified silane coupling agent physically attached. The dielectric loss tangent of the obtained glass cloth E is measured using the same method as in Example 1. It should be noted that the bulk dielectric loss tangent of the glass is set to 0.0015.

[0188] (Example 6)

[0189] Glass cloth F was obtained in the same manner as in Example 1, except that the glass cloth was immersed in a treatment solution containing 0.95% of 5-hexenyltrimethoxysilane Z6161 (manufactured by Dow Toray Co., Ltd.) as a silane coupling agent, squeezed out, and then heated and dried at 110°C for 1 minute to fix the silane coupling agent. The converted thickness of the glass cloth F was calculated from its weight per unit area and density, and the dielectric loss tangent of the glass cloth F was measured.

[0190] (Example 7)

[0191] Glass cloth G was obtained in the same manner as in Example 1, except that the glass cloth was immersed in a treatment solution containing 0.85% of 3-acryloxypropyltrimethoxysilane (KBM-5103 (manufactured by Shin-Etsu Silicones) dispersed therein as a silane coupling agent, and after squeezing the solution, the glass cloth was heated and dried at 110°C for 1 minute to fix the silane coupling agent. The converted thickness of the glass cloth G was calculated from the weight per unit area and density, and the dielectric loss tangent of the glass cloth G was measured.

[0192] (Example 8)

[0193] Glass cloth H was obtained in the same manner as in Example 1, except that the glass cloth was immersed in a treatment solution containing 0.50% of 5-hexenyltrimethoxysilane Z6161 (manufactured by Dow Toray Co., Ltd.) and 0.45% of 3-methacryloxypropyltrimethoxysilane Z6030 (manufactured by Dow Toray Co., Ltd.) as silane coupling agents. After squeezing out the solution, the glass cloth was heated and dried at 110°C for 1 minute to fix the silane coupling agent. The converted thickness of the glass cloth H was calculated from the weight per unit area and density, and the dielectric loss tangent of the glass cloth H was measured.

[0194] (Example 9)

[0195] Glass cloth I was obtained in the same manner as in Example 1, except that the glass cloth was immersed in a treatment solution containing 0.45% of 3-acryloxypropyltrimethoxysilane KBM-5103 (manufactured by Shin-Etsu Silicones) and 0.50% of 3-methacryloxypropyltrimethoxysilane Z6030 (manufactured by Dow Toray Co., Ltd.) as silane coupling agents. After squeezing out the solution, the glass cloth was heated and dried at 110°C for 1 minute to fix the silane coupling agent. The converted thickness of the glass cloth I was calculated from the weight per unit area and density, and the dielectric loss tangent of the glass cloth I was measured.

[0196] (Comparative Example 1)

[0197] Glass cloth H was obtained in the same manner as in Example 1 except that deoiling was performed by heating at 360° C. for 48 hours and that the finishing washing and finishing drying steps were not performed. The dielectric loss tangent of the obtained glass cloth H was measured in the same manner as in Example 1.

[0198] (Comparative Example 2)

[0199] Glass cloth I was obtained in the same manner as in Comparative Example 1 except that degreasing was performed by heating at 800° C. for 15 seconds. The dielectric loss tangent of the obtained glass cloth I was measured by the same method as in Example 1.

[0200] (Comparative Example 3)

[0201] Glass cloth J was obtained in the same manner as in Example 1 except that deoiling was performed by heating at 360° C. for 48 hours. The dielectric loss tangent of the obtained glass cloth J was measured by the same method as in Example 1.

[0202] [Method for producing laminated board]

[0203] For the glass cloth obtained in the above examples and comparative examples, 45 parts by mass of polyphenylene ether (SABIC, 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-butylisocyanurate) were added to a stainless steel container and stirred at room temperature for 1 hour to prepare a varnish. The glass cloth was impregnated with the prepared varnish and dried at 115°C for 1 minute to obtain a prepreg. 8 sheets of the obtained prepreg were stacked, and copper foil with a thickness of 12 μm was stacked on top and bottom. The mixture was heated at 200°C and 40 kg / cm 2 The laminate was obtained by heating and pressing for 120 minutes.

[0204] [Evaluation Method for Heat Resistance of Laminated Plate]

[0205] After removing the copper foil from the laminate obtained as described above, the laminate was heated in a pressure cooker at 133°C for 180 hours to absorb water. The laminate after water absorption was then immersed in a solder bath at 288°C for 20 seconds, and the presence of swelling due to delamination at the glass cloth / resin interface was visually inspected (four tests were performed for each level).

[0206] Table 2 shows heat resistance:

[0207] If there is no expansion in all the 4 laminated sheets, it is indicated as "A".

[0208] If there is expansion in 1 or 2 sheets of laminated boards, it is indicated as "B".

[0209] If there is expansion in 3 to 4 laminated sheets, it is indicated as "C".

[0210] The less expanded the glass cloth is, the better its heat resistance is.

[0211] Tables 1 and 2 show the production conditions and evaluation results of Examples and Comparative Examples.

[0212] [Table 1]

[0213]

[0214] [Table 2]

[0215]

[0216] The heat resistance evaluation results of the laminated plates are shown in Table 3.

[0217] [Table 3]

[0218] Table 3

[0219]

[0220] Industrial applicability

[0221] The glass cloth of the present invention has industrial applicability as a base material used in printed wiring boards used in the electronic and electrical fields.

Claims

1. A glass cloth woven from glass yarns comprising a plurality of glass filaments as warp and weft, wherein the surface of the glass cloth is treated with a surface treatment agent, and the difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent measured using a split cylindrical resonator at 10 GHz exceeds 0 and is 1.0×10 -3 the following.

2. The glass cloth according to claim 1, wherein The average filament diameter of the glass filaments is 2.5 to 9.0 μm.

3. The glass cloth according to claim 1 or 2, wherein The average filament diameter of the glass filaments is 3.5 to 5.0 μm.

4. The glass cloth according to claim 1 or 2, wherein The warp and weft yarns have a beating density of 10 to 120 yarns / inch.

5. The glass cloth according to claim 1 or 2, wherein The warp and weft yarns have a beating density of 40 to 100 yarns / inch.

6. The glass cloth according to claim 1 or 2, wherein The glass cloth has a weight per unit area of ​​8 to 250 g / m 2 .

7. The glass cloth according to claim 1 or 2, wherein The weight of the glass cloth, i.e., the weight per unit area, is 8 to 50 g / m 2 .

8. The glass cloth according to claim 1 or 2, wherein The difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent is 8.0×10 -4 the following.

9. The glass cloth according to claim 8, wherein The difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent is 6.0×10 -4 the following.

10. The glass cloth according to claim 9, wherein The difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent is 4.0×10 -4 the following.

11. The glass cloth according to claim 10, wherein The difference between the dielectric loss tangent of the glass cloth and the bulk dielectric loss tangent is 2.0×10 -4 the following.

12. The glass cloth according to claim 1 or 2, wherein The glass yarns constituting the glass cloth have a silicon (Si) content of 95% by mass to 100% by mass in terms of silicon dioxide (SiO 2 ).

13. The glass cloth according to claim 1 or 2, wherein The Si content of the glass yarn constituting the glass cloth is 99.0% by mass to 100% by mass in terms of SiO2.

14. The glass cloth according to claim 1 or 2, wherein The Si content of the glass yarn constituting the glass cloth is 99.9% by mass to 100% by mass in terms of SiO2.

15. The glass cloth according to claim 1 or 2, wherein The bulk dielectric loss tangent of the glass constituting the glass yarn exceeds 0 at 10 GHz and is 2.5×10 -3 the following.

16. The glass cloth according to claim 1 or 2, wherein: The surface treatment agent contains a silane coupling agent represented by the following general formula (1): X(R) 3-n Yes n (1) In formula (1), X is an organic functional group having at least one of an amino group and an unsaturated double bond group, wherein the unsaturated double bond group has free radical reactivity, Y is each independently an alkoxy group, n is an integer of 1 to 3, and R is each independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.

17. The glass cloth according to claim 16, wherein X in the general formula (1) is an organic functional group that does not form a salt with an ionic compound.

18. The glass cloth according to claim 16, wherein X in the general formula (1) does not contain an amine or ammonium cation.

19. The glass cloth according to claim 16, wherein X in the general formula (1) is an organic functional group having one or more methacryloyloxy groups or acryloyloxy groups.

20. The glass cloth according to claim 16, wherein The molecular weight of the silane coupling agent is 100-600.

21. The glass cloth according to claim 16, wherein The molecular weight of the silane coupling agent is 200-450.

22. The glass cloth according to claim 16, wherein Two or more of the above-mentioned silane coupling agents having different molecular weights are used.

23. The glass cloth according to claim 15, wherein The bulk dielectric loss tangent of the glass constituting the glass yarn is 2.0×10 -3 the following.

24. The glass cloth according to claim 23, wherein The bulk dielectric loss tangent of the glass constituting the glass yarn is 1.7×10 -3 the following.

25. The glass cloth according to claim 24, wherein The bulk dielectric loss tangent of the glass constituting the glass yarn is 1.5×10 -3 the following.

26. The glass cloth according to claim 25, wherein The bulk dielectric loss tangent of the glass constituting the glass yarn is 1.2×10 -3 the following.

27. The glass cloth according to claim 26, wherein The bulk dielectric loss tangent of the glass constituting the glass yarn is 1.0×10 -3 the following.

28. The glass cloth according to claim 1 or 2, wherein The total carbon content of the glass cloth is 0.02% to 0.5%.

29. The glass cloth according to claim 1 or 2, wherein The total carbon content of the glass cloth is 0.02% to 0.1%.

30. The glass cloth according to claim 1 or 2, which is used for a printed wiring board base material.

31. A prepreg comprising the glass cloth according to any one of claims 1 to 30, a thermosetting resin, and an inorganic filler.

32. A printed wiring board comprising the prepreg according to claim 31.

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