TW202206390A - Glass cloth, prepreg, and printed circuit board wherein the glass cloth is composed of glass yarns containing a plurality of glass filaments as warps and wefts - Google Patents

Abstract

An object of the present invention is to provide a low-dielectric glass cloth having suppressed strength reduction, and a prepreg and a printed circuit board using the low-dielectric glass cloth. The glass cloth of the present invention is composed of glass yarns containing a plurality of glass filaments as warps and wefts, and in the following formula (1), the weight reduction coefficient obtained by multiplying the weight reduction ratio of the glass composition by the average radius of the glass filaments during the heat treatment at 380 DEG C for 2 hours is 0.18 or more and 0.45 or less, and the iron content of the glass cloth is greater than 0.1 mass % and less than 0.4 mass % in terms of Fe2O3 conversion. Weight reduction coefficient = weight reduction ratio (%) * the average radius of the glass filaments ([mu]m) … (1).

Description

Glass cloth, prepregs, and printed circuit boards

The present invention relates to a glass cloth, a prepreg, and a printed circuit board.

With the development of the information and communication society in recent years, data communication and/or signal processing have been performed in large volumes and at high speed, and the reduction of the dielectric constant of printed circuit boards used in electronic equipment is progressing remarkably. Therefore, regarding the glass cloth constituting the printed circuit board, many low-dielectric glass cloths have also been proposed.

For example, the low-dielectric glass cloth disclosed in Patent Document 1 contains a large amount of B ₂ O ₃ in the glass composition compared to the E glass cloth commonly used in the past, and simultaneously adjusts the amount of other components such as SiO ₂ . Low dielectric constant. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 11-292567

[Problems to be Solved by Invention]

However, if the content ratio of B ₂ O ₃ in the glass yarn is increased in order to lower the dielectric constant of the glass cloth, the elastic modulus of the glass yarn is lowered, and furthermore, due to heat treatment such as de-sizing treatment performed in the production process, the glass The strength of the cloth is significantly reduced. Therefore, there is a problem that the glass cloth is easily broken. In the case of producing a prepreg using such a glass cloth, when an external load is applied to the glass cloth, such as an operation of controlling the resin adhesion amount, the glass cloth is broken, causing production problems.

In this regard, Patent Document 1 discloses a method of setting the content of B ₂ O ₃ to be less than 20% by mass and setting the content of CaO to a specific range during spinning of glass yarns, whereby This inhibits the volatilization of B ₂ O ₃ . However, when the content of B ₂ O ₃ is less than 20 mass %, the requirement for lowering the dielectric constant cannot be sufficiently met, and as a result, a glass cloth having a low dielectric and suppressed strength reduction cannot be realized. Furthermore, it is known that when the weight reduction by heat treatment is within a specific range, the strength reduction becomes more serious.

The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a low-dielectric glass cloth in which strength reduction is suppressed, and a prepreg and a printed circuit board using the low-dielectric glass cloth. [Technical means to solve problems]

The inventors of the present invention have made intensive studies in order to solve the above-mentioned problems, and as a result, they have found that the above-mentioned problems can be solved by adjusting the content of Fe in the glass cloth having a specific weight reduction tendency, and completed the present invention.

That is, the present invention is as follows. [1] A glass cloth comprising glass yarns containing a plurality of glass filaments as warps and wefts, and in the following formula (1), as the amount derived from a glass component in a heat treatment at 380° C. for 2 hours The weight reduction factor obtained by multiplying the weight reduction ratio and the average radius of the above-mentioned glass filaments is 0.18 or more and 0.45 or less. The Fe content of the glass cloth is more than 0.1 mass % and less than 0.4 mass % in terms of Fe ₂ O ₃ . [2] The glass cloth according to [1], wherein the Fe content of the glass cloth exceeds 0.2 mass % and is less than 0.4 mass % in terms of Fe ₂ O ₃ . [3] The glass cloth according to [2], wherein the Fe content of the glass cloth exceeds 0.3% by mass and less than 0.4% by mass in terms of Fe ₂ O ₃ . [4] The glass cloth according to any one of [1] to [3], wherein the F content of the glass cloth exceeds 0.005 mass % and is less than 0.4 mass %. [5] The glass cloth as described in [4], wherein the F content of the glass cloth exceeds 0.005 mass % and is less than 0.2 mass %. [6] The glass cloth as described in [5], wherein the F content of the glass cloth exceeds 0.005 mass % and is less than 0.1 mass %. [7] The glass cloth according to any one of [1] to [6], wherein the Si content of the glass cloth is 40 to 60 mass % in terms of SiO ₂ , and the content of B is 40 to 60 mass % in terms of B ₂ O ₃ . 15 to 30 mass %. [8] The glass cloth according to [7], wherein the Al content of the glass cloth is 10 to 20 mass % in terms of Al ₂ O ₃ , the Ca content is 4 to 12 mass % in terms of CaO, and the Mg content is MgO conversion is 1 mass % or less. [9] The glass cloth according to any one of [1] to [8], wherein the elastic modulus of the glass cloth is 50 to 70 GPa. [10] The glass cloth according to [9], wherein the elastic modulus of the glass cloth is 50 to 63 GPa. [11] The glass cloth according to any one of [1] to [10], wherein the average diameters of the glass filaments constituting the warp yarns and the weft yarns are each independently 3.5 to 5.4 μm. [12] The glass cloth according to any one of [1] to [11], which has a dielectric constant of 5.0 or less at a frequency of 1 GHz. [13] A prepreg comprising: the glass cloth as described in any one of [1] to [12]; and a matrix resin impregnated in the glass cloth. [14] A printed wiring board including the glass cloth according to any one of [1] to [12]. [Effect of invention]

According to the present invention, it is possible to provide a low-dielectric glass cloth in which strength reduction is suppressed, and a prepreg and a printed circuit board using the low-dielectric glass cloth.

Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described in detail, but the present invention is not limited to this, and various changes can be made without departing from the gist.

[Glass Cloth] The glass cloth of the present embodiment is composed of glass yarns including a plurality of glass filaments as warps and wefts, and in the following formula (1), it is derived from glass as a heat treatment at 380° C. for 2 hours. The weight reduction coefficient obtained by multiplying the weight reduction ratio of the components and the average radius of the glass fiber is 0.18 or more and 0.45 or less, and the Fe content of the glass cloth exceeds 0.1 mass % and does not reach 0.4 mass % in terms of Fe ₂ O ₃ . Weight reduction factor = weight reduction ratio (%) × average radius of glass fiber (μm)・・・(1)

In the heat treatment of the glass cloth with a low dielectric constant or the heat treatment in the subsequent steps thereof, the strength of the glass yarn is reduced. Due to this decrease in strength and the low modulus of elasticity of the glass yarn constituting the low-dielectric glass cloth, the low-dielectric glass cloth is more likely to be broken than those using other glass yarns such as E-glass. On the other hand, in the present embodiment, by adjusting the content of Fe (iron) in the glass, and more preferably the content of F (fluorine), in the glass cloth having a specific weight reduction tendency, the occurrence of heat treatment is suppressed. strength is reduced.

The reason why the strength reduction can be suppressed by the adjustment of the Fe content is not limited, but the following viewpoints are considered. During spinning, even if the glass component volatilizes under high temperature conditions and a sparse part is formed in the glass yarn, the molten glass can flow and fill the part, and the glass yarn becomes sparse due to the volatilization of the glass component accompanying the weight reduction. Part of it can be eliminated by this flow. On the other hand, even if the glass yarn constituting the glass cloth produces a sparse portion due to volatilization of the glass component, the glass cannot flow and the portion is filled. Under such circumstances, Fe may have a maintenance effect on the portion where the glass yarn becomes sparse due to volatilization of the glass component in the glass cloth of the present embodiment.

In addition, there is no limitation on the reason why the reduction in strength can be further suppressed by adjusting the F content, but there are the following viewpoints. F reduces the viscosity of the molten glass in the glass manufacturing process. Therefore, when the content of F is within a specific range, when metal components such as Fe are incorporated into the glass structure, they are uniformly dispersed without being localized, and a uniform glass can be formed. It is considered that by uniformly dispersing Fe, the above-mentioned Fe's maintaining effect on the portion where the glass yarn becomes sparse due to volatilization of the glass component can be more effectively expressed. In addition, it is considered that if a relatively hard part is localized in the glass due to the localization of Fe and the like, fracture is likely to occur from this part as a starting point. However, it is considered that by adjusting the F content to alleviate such localization, the strength reduction can be further suppressed. .

By having the above-mentioned configuration, in this embodiment, the problem of fracture of the low-dielectric glass cloth can be solved, and a glass cloth with high fracture resistance and low dielectric constant can be provided. Hereinafter, the configuration of this embodiment will be described in more detail.

(weight reduction factor) The weight reduction factor (hereinafter, also simply referred to as "weight reduction factor") obtained as the product of the weight reduction ratio derived from the glass component and the average radius of the glass filaments when the glass cloth was heat-treated at 380°C for 2 hours was 0.18 0.45 or more, preferably 0.19 or more and 0.42 or less, more preferably 0.20 or more and 0.39 or less, still more preferably 0.20 or more and 0.35 or less.

The "weight reduction ratio derived from the glass component" means that the weight reduction ratio at the time of heat treatment at 380° C. for 2 hours is due to the disappearance of the glass component due to volatilization or the like during the heat treatment. As described below, when a surface treatment agent such as a silane coupling agent adheres to the glass cloth, or when a large amount of organic impurities adheres, the weight reduction ratio of this embodiment is to remove the physical material with a good solvent such as alcohol or acetone in advance. Calculated after adsorbed surface treatment agents such as silane coupling agents or organic impurity adhering components. Therefore, the weight reduction ratio after the heat treatment of the glass cloth after removing the adhering components that are thermally decomposed at 380° C. becomes the reduction ratio derived from the glass component.

In addition, it was confirmed that the weight reduction ratio depends on the filament diameter of the glass yarn. The weight reduction ratio varies with the glass filament diameter, the smaller the filament diameter, the greater the weight reduction. On the other hand, the product of the weight reduction ratio and the wire radius is not affected by the wire diameter and is approximately a fixed value. Therefore, in this embodiment, as the weight reduction coefficient, the wire diameter is normalized.

Since the weight reduction coefficient is 0.18 or more, the strength is likely to decrease if this state is maintained. However, by adjusting the Fe content as described below, and further adjusting the F content as a preferred aspect, in this embodiment, the reduction in strength can be suppressed, and, depending on the relationship of the composition constituting the glass cloth, a lower intermediate Electric constant glass cloth. In addition, when the weight reduction coefficient is 0.45 or less, the effect of suppressing the reduction in strength due to Fe is effectively exhibited, and a significant reduction in strength can be suppressed.

The measurement method of the weight reduction ratio can be performed in the following order. First, put the glass cloth in a dryer at 105℃±5℃ for 60 minutes, then move the glass cloth to the dryer and let it cool until room temperature. After standing to cool, the weight of the glass cloth (glass cloth weight a) was weighed in units of 0.1 mg or less. Next, the glass cloth was heated at 380° C. for 2 hours, and then the glass cloth was moved to a desiccator and left to cool until room temperature. After standing to cool, the glass cloth was weighed in units of 0.1 mg or less (glass cloth weight b after heat treatment). Next, the weight reduced by the heat treatment was obtained, and the weight reduction ratio (%) was calculated by the following formula (2). Weight reduction ratio (%)＝(a－b)/a×100・・・(2)

The weight reduction ratio obtained in the above manner is preferably 0.04 to 0.5%, more preferably 0.05 to 0.3%, and still more preferably 0.06 to 0.25%. Since the weight reduction ratio is 0.04% or more, the strength is likely to decrease if this state is maintained. However, by adjusting the Fe content as described below, and further adjusting the F content as a preferred aspect, in this embodiment, the reduction in strength can be suppressed, and, depending on the relationship of the composition constituting the glass cloth, a lower intermediate Electric constant glass cloth. In addition, when the weight reduction ratio is 0.5% or less, the effect of suppressing the reduction in strength due to Fe is effectively exhibited, and a significant reduction in strength can be suppressed.

Next, the average diameter of the glass filaments constituting the glass yarn of the glass cloth was measured in accordance with JIS R3420, and the average filament radius, which is a half of the filament diameter, was determined. In this embodiment, when abbreviated as glass filament, it means a glass monofilament. In addition, the average radius of the glass filament used for calculating the weight reduction coefficient is the average radius before the heat treatment. The average radius of the glass filaments obtained in this way is preferably 1.25 to 4.5 μm, more preferably 1.5 to 3.75 μm, and still more preferably 1.75 to 2.7 μm.

Furthermore, the glass cloth used for the measurement method of the said weight reduction ratio can be suitably pretreated. For example, in the glass cloth drawn out from the intermediate roll after the de-binding process (heat cleaning), the glass filaments are not attached to the glass filaments. Therefore, it can be used as it is for the measurement method of the above-mentioned weight reduction ratio.

On the other hand, when a glass cloth coated with a surface treatment agent such as a silane coupling agent is used as an object to obtain the weight reduction ratio, the physisorbed silane coupling agent can be removed by washing with a good solvent such as alcohol or acetone in advance. After waiting for the surface treatment agent, the weight reduction coefficient was obtained by the above-mentioned method.

Furthermore, the "physical adsorption silane coupling agent" refers to the silane coupling agent attached to the glass fiber, not the silane coupling agent bonded to the glass fiber by chemical bond. On the other hand, the silane coupling agent bonded to the glass fiber by chemical bond is called "chemisorbed silane coupling agent".

In addition, when the glass cloth contains organic impurities (starch-based sizing agent applied in the glass yarn manufacturing process, combustion residue of the previous sizing agent in the thermal cleaning step, etc.) After removing the organic impurities adhering to the glass cloth by washing and removing operations such as alcohols, acetone, etc., the weight reduction coefficient was obtained by the above-mentioned method.

The above cleaning is to remove physically adsorbed silane coupling agents or organic impurities, not to remove chemically adsorbed silane coupling agents. However, even if heated at 380°C for 2 hours, the chemisorbed silane coupling agent will not decompose, or even partially decomposed will not exceed the error range. Therefore, in the measurement of the weight reduction ratio in this embodiment, it is not necessary to use Pretreatment removes chemisorbed silane coupling agents.

In addition, from the viewpoint of simplifying the judgment of whether or not to perform pretreatment, the weight reduction ratio can also be measured uniformly by using a glass cloth that has been washed in advance with a good solvent such as alcohol and acetone. Thereby, the weight reduction ratio can be carried out in the same state, regardless of whether it is the glass cloth drawn from the intermediate roll after the depaste treatment (thermal cleaning), or the glass cloth to which the silane coupling agent or organic impurity adhered to the physical adsorption is attached. measurement.

As another method, when obtaining the above-mentioned weight reduction coefficient, the amount of surface treatment or organic impurities before and after heating may be quantified, and the weight loss due to the surface treatment agent may be subtracted from the obtained weight loss. Thereby, the weight reduction coefficient derived from the glass component was calculated|required. As a method for obtaining the weight reduction amount due to the surface treatment agent, a known method such as a quantitative method for a silane coupling agent described in Japanese Patent No. 6472082 and the like can also be used.

The weight reduction coefficient can be adjusted by the increase or decrease of, for example, relatively volatile components in the composition of the glass cloth, such as the B content, etc., and from the same viewpoint, it can also be adjusted by the increase or decrease of other components.

In addition, the weight reduction factor can also be adjusted by adjusting the space filling rate (weaving density or thickness) of the glass in the glass cloth, adjusting the dissociation state of the monofilaments constituting the glass yarn bundle by opening process, etc., and the glass used It can be adjusted by adjusting the single filament diameter of the yarn, etc. It can also be adjusted by increasing or decreasing the chance of the glass surface being exposed to a high-temperature gas atmosphere. That is, the weight reduction factor is not determined only by the composition of the glass cloth.

(Composition) Hereinafter, the composition of the glass cloth of the present embodiment will be described. Furthermore, the composition of the glass cloth is synonymous with the composition of the glass yarn constituting the glass cloth. In the composition of the glass cloth of the present embodiment, the Fe content in terms of Fe ₂ O ₃ is more than 0.1 mass % and less than 0.4 mass %, preferably more than 0.2 mass % and less than 0.4 mass %, more preferably more than 0.3 mass % % by mass and less than 0.4% by mass, and the optimum range is more than 0.3% by mass and 0.38% by mass or less. When the Fe content exceeds 0.1 mass %, the reduction in strength of the glass cloth due to heat treatment can be suppressed. Moreover, since Fe content is less than 0.4 mass %, it can suppress that the intensity|strength of the glass cloth itself before heat processing falls by too much Fe content on the contrary. The Fe content can be adjusted according to the amount of raw materials used in the production of glass filaments, or it can be refined and removed or added during the production of glass filaments.

In addition, the strength reduction due to too much Fe content is not particularly limited, but the following viewpoints are considered. It is considered that the glass yarn is basically composed of an amorphous part, but the part in which Fe is present is a part with relatively high crystallinity. It is considered that depending on the existence of the high crystallinity part, the local weak part becomes obvious, but in the present embodiment, by adjusting the Fe content to a certain amount or less, the reduction in the strength of the glass cloth can be suppressed.

Moreover, the F content in the composition of the glass cloth of the present embodiment is preferably more than 0.005 mass % and less than 0.4 mass %, more preferably more than 0.005 mass % and less than 0.2 mass %, and still more preferably more than 0.005 mass % And less than 0.1 mass %. When the F content exceeds 0.005 mass %, there is a tendency that the strength of the glass cloth due to the heat treatment is lowered and thus suppressed. Moreover, since the F content is less than 0.4 mass %, it can suppress that the intensity|strength of the glass cloth itself before heat processing falls by too much F content instead. The content of F can be adjusted according to the amount of raw materials used for glass fiber production.

In addition, the strength reduction by too much F content is not specifically limited, However, it has the following viewpoints. It is considered that the greater the F content, the stronger the phase separation of the glass composition, and it is considered that it is difficult to make the glass composition uniform.

In a preferred aspect of the present embodiment, by setting both the Fe content and the F content to the above-mentioned specific ranges, there is a tendency that the effect of suppressing the reduction in strength due to heat treatment is further enhanced.

The Si content of the glass cloth is preferably 40 to 60 mass % in terms of SiO ₂ , more preferably 45 to 55 mass %, further preferably 47 to 53 mass %, and still more preferably 48 to 52 mass %. Si is a component that forms the skeleton structure of the glass yarn. When the Si content is 40% by mass or more, in addition to suppressing the decrease in strength caused by heat treatment, the strength of the glass yarn itself before heat treatment is further improved. The production process and use of glass cloth In subsequent steps such as the manufacture of glass cloth prepregs, there is a tendency for glass cloth to break and be suppressed. Moreover, there exists a tendency for the dielectric constant of a glass cloth to fall further by Si content being 40 mass % or more. On the other hand, when the Si content is 60 mass % or less, in the production process of the glass fiber, the viscosity at the time of melting is further reduced, and there is a tendency to obtain a glass fiber with a more homogeneous glass composition. Therefore, since it is difficult to produce a portion where local devitrification is easy or a portion where air bubbles are not easily escaped in the obtained glass filament, it is difficult for the glass filament to produce a portion with weak local strength. As a result, the glass cloth including the glass yarn obtained by using the glass filament becomes Not easy to break. The Si content can be adjusted according to the amount of the raw material used for glass filament production.

The B content of the glass cloth is preferably 15 to 30 mass %, more preferably 17 to 28 mass %, more preferably 20 to 27 mass %, and still more preferably 21 to 25 mass % in terms of B ₂ O ₃ conversion. , more preferably 21.5 to 24 mass %. When the B content is 15% by mass or more, the dielectric constant tends to further decrease. Since the strength of the glass cloth is strong and the moisture absorption resistance is also excellent, it is preferable that the content of B is 30 mass % or less. In addition, when the B content is 30% by mass or less, the volatilization amount of the glass component due to heat treatment such as de-sizing treatment can be kept small, so that the strength can be suppressed from lowering, and the moisture absorption resistance drop can also be suppressed. , there is a tendency to further improve the insulation reliability. The content of B can be adjusted according to the amount of raw materials used for glass filament production. Furthermore, in the case of a situation that may vary in the production of glass filaments, the feeding amount can be adjusted in anticipation of the situation.

Moreover, the glass cloth may have another composition in addition to the above-mentioned composition. It does not specifically limit as another composition, For example, Al, Ca, Mg, P, Na, K, Ti, Zn, etc. are mentioned.

The Al content of the glass cloth is preferably 10 to 20 mass %, more preferably 11 to 18 mass %, and still more preferably 12 to 17 mass %, in terms of Al ₂ O ₃ . When the Al content is within the above range, the electrical properties and strength tend to be further improved. The Al content can be adjusted according to the amount of the raw material used for glass filament production.

The Ca content of the glass cloth is preferably 4.0 to 12 mass %, preferably 5.7 to 10 mass %, and more preferably 6.0 to 9.0 mass % in terms of CaO. When the Ca content is 4.0 mass % or more, in the production process of the glass fiber, the viscosity at the time of melting is further reduced, and there is a tendency to obtain a glass fiber with a more homogeneous glass composition. Moreover, when the Ca content is 10 mass % or less, there exists a tendency for a dielectric constant to further improve. The Ca content can be adjusted according to the amount of the raw material used for glass fiber production.

The Mg content of the glass cloth in terms of MgO is preferably 1.0 mass % or less, more preferably 0.7 mass % or less, more preferably 0.01 mass % or more and 0.7 mass % or less, and still more preferably 0.05 mass % or more and 0.6 mass % Below, more preferably, it is 0.05 mass % or more and 0.45 mass % or less. When the Mg content is 5 mass % or less, the glass cloth tends to be less prone to breakage when the glass cloth passes through a squeeze roll, a nip roll, etc. in a wet state in the fiber opening step or the surface treatment step during glass cloth production. In addition, phase separation at the time of glass fiber production is suppressed, and the moisture absorption resistance of the obtained glass fiber is further improved. Thereby, the obtained printed circuit board is not easily affected by the use environment of the high-humidity environment, and the environmental dependence of the dielectric constant can be reduced. The Mg content can be adjusted according to the amount of the raw material used for glass fiber production.

The ratio of the Ca content to the Mg content is preferably 5.0 to 50, more preferably 10 to 45, still more preferably 15 to 40, still more preferably 20 to 35, still more preferably 20 to 30. When the ratio of the Ca content to the Mg content is within the above range, a more homogeneous glass fiber with stronger strength and excellent moisture absorption resistance can be obtained, which tends to be less prone to breakage and lower in environmental dependence of the dielectric constant.

In addition, each content mentioned above can be measured by ICP (inductively coupled plasma, inductively coupled plasma) emission spectrometry. Specifically, regarding the Si content and the B content, the weighed glass cloth sample can be decomposed under pressure with sodium hydroxide, dissolved with dilute nitric acid, and filtered, and the insoluble components can be dissolved with sodium carbonate, and the filtrates can be combined. The volume was determined, and the obtained sample was measured by ICP emission spectrometry.

Regarding Fe content, Al content, Ca content, and Ma content, the weighed glass cloth sample can be decomposed by heating with perchloric acid, nitric acid, hydrochloric acid and hydrogen fluoride, then heated and dissolved with dilute aqua regia, and then filtered and separated, and the filtrate can be fixed to volume , and then, the insoluble components were heated and decomposed with sulfuric acid, nitric acid, hydrochloric acid, and hydrogen fluoride, and the obtained samples were measured and obtained by ICP emission spectrometry. Furthermore, as an ICP emission spectrometer, PS3520VDD II manufactured by Hitachi High-Tech Science can be used.

In addition, regarding the F content, after burning the glass cloth sample taken out in a tubular electric furnace, the generated gas can be absorbed into the absorption liquid. About this solution, fluoride ion (F ^- ) was measured with an ion chromatograph, and the content in a sample was calculated|required. Further, as the combustion device, an automatic sample combustion device (AQF-2100S) manufactured by Mitsubishi Chemical Analytech can be used, and as the measurement device, an ion chromatograph ICS-1500 manufactured by Thermo Fisher Scientific can be used.

The elastic modulus of the glass cloth is preferably 50 to 70 GPa, more preferably 50 to 63 GPa, and still more preferably 53 to 63 GPa. The lower the elastic modulus of the glass cloth, the easier it is to break. Therefore, since the elastic modulus is 50 GPa or more, in the glass cloth manufacturing steps such as the fiber opening step and the surface treatment step, when the glass cloth passes through a squeeze roll or a nip roll in a wet state, there is a tendency that breakage is less likely to occur. . In addition, in the subsequent steps such as the manufacture of the prepreg, when the glass cloth is passed through the slit for the purpose of controlling the impregnation amount of the resin into the glass cloth, there is a tendency that the breakage is less likely to occur. When the elastic modulus of the glass wiring is 70 GPa or less, the texture of the glass cloth becomes soft, and when the glass cloth passes through a narrow interval such as a squeeze roll or a nip roll, it tends to be less prone to breakage. Moreover, since the elastic modulus of glass cloth is 70 GPa or less, there exists a tendency for a dielectric constant to further fall relatively relatively. The elastic modulus can be measured by the method described in the examples. In addition, the elastic modulus can be adjusted by the composition of the glass yarn.

At a frequency of 1 GHz, the dielectric constant of the glass cloth of the present embodiment is preferably 5.0 or less, more preferably 4.7 or less, still more preferably 4.5 or less, particularly preferably 4.0 or less. Furthermore, in this embodiment, when referring to the dielectric constant, unless otherwise specified, it refers to the dielectric constant at a frequency of 1 GHz.

(constitute) The glass yarn is obtained by bundling a plurality of glass yarns and twisted as necessary, and the glass cloth is obtained by weaving the above-mentioned glass yarn as a warp and a weft. Glass yarns are classified as multifilaments and glass filaments are classified as monofilaments.

The average diameters of the glass filaments constituting the warp and the weft are each independently preferably 2.5 to 9 μm, more preferably 3.0 to 7.5 μm, and still more preferably 3.5 to 5.4 μm. When the average diameter of the glass filaments is within the above range, when using a mechanical drill, carbon dioxide gas laser, UV-YAG (Ultraviolet-Yttrium Aluminum Garnet, UV-Yttrium Aluminum Garnet) laser to process the obtained substrate , there is a tendency to further improve the processability. Therefore, a thin and high-density packaged printed circuit board can be realized. In particular, when the average diameter is 5.4 μm or less, the surface area per unit volume is increased, and the strength reduction due to heat treatment is likely to occur. Therefore, the effect of suppressing the strength reduction in this embodiment becomes more important. In addition, since the average diameter is 2.5 μm or more, the surface area becomes small and the volatilization of the glass component is suppressed. In addition to that, in the glass cloth manufacturing steps such as the fiber opening step and the surface treatment step, the glass cloth is passed in a wet state. There is a tendency to be less prone to breakage when squeezed rolls or nip rolls are used. In addition, in the subsequent steps such as the manufacture of the prepreg, when the glass cloth is passed through the slit for the purpose of controlling the impregnation amount of the resin into the glass cloth, there is a tendency that the breakage is less likely to occur.

The weaving density of the warp yarns and the weft yarns constituting the glass cloth is preferably 30 to 130 yarns/25 mm, more preferably 40 to 120 yarns/25 mm, and still more preferably 50 to 110 yarns/25 mm.

The thickness of the glass cloth is preferably 8-100 μm, more preferably 10-50 μm, further preferably 12-35 μm, and most preferably 12-30 μm. When the thickness of the glass cloth is within the above-mentioned range, there is a tendency to obtain a thin glass cloth with relatively high strength. In particular, when the thickness is 8 μm or more, the ratio of the glass filaments occupying the vicinity of the surface of the glass cloth decreases, so that the volatilization amount of the glass component tends to decrease. In addition, when the thickness is 100 μm or less, the ratio of the glass filaments occupying the vicinity of the surface of the glass cloth increases, so that the strength reduction due to the increase in the volatilization amount of the glass component tends to occur, and the effect of suppressing the strength reduction of the present invention becomes more important. Furthermore, the weight reduction factor depends on the diameter of the filaments constituting the glass cloth, so it is difficult to depend on the thickness. This tendency is maintained at least within the above-mentioned thickness range.

The cloth weight (weight per unit area) of the glass cloth is preferably 8-250 g/m ² , more preferably 8-100 g/m ² , still more preferably 8-50 g/m ² , particularly preferably 8-35 g/m ² .

The weave structure of the glass cloth is not particularly limited, and for example, a weave structure such as a plain weave, a square weave, a satin weave, and a twill weave can be exemplified. Among them, a plain weave structure is more preferred.

(surface treatment) The glass cloth can also be surface-treated with a surface-treating agent. It does not specifically limit as a surface treatment agent, For example, a silane coupling agent is mentioned, and water, an organic solvent, an acid, a dye, a pigment, a surfactant, etc. may be used together as needed.

A silane coupling agent is not specifically limited, For example, the compound represented by Formula (1) is mentioned. X(R) _3-n SiY _n・・・(1) (In formula (1), X is an organic functional group having at least one of an amine group and an unsaturated double bond group, and Y is each independently an alkane In the oxy group, n is an integer of 1 or more and 3 or less, and R is each independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group).

X is preferably an organic functional group having at least 3 or more among amine groups and unsaturated double bond groups, and X is more preferably an organic functional group having at least 4 or more among amine groups and unsaturated double bond groups.

Although any form can be used as said alkoxy group, from a viewpoint of stabilizing treatment to glass cloth, an alkoxy group having 5 or less carbon atoms is preferable.

Specific examples of the silane coupling agent include N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-( N-vinylbenzylaminoethyl)-γ-aminopropylmethyldimethoxysilane and its hydrochloride, N-β-(N-bis(vinylbenzyl)aminoethyl) -γ-Aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-bis(vinylbenzyl)aminoethyl)-N-γ-(N-vinylbenzyl)- γ-Aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-benzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β -(N-benzylaminoethyl)-γ-aminopropyltriethoxysilane and its hydrochloride, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ- (2-aminoethyl)aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloyloxypropyltrimethylsilane, acryloxy Well-known monomers such as propylpropyltrimethoxysilane, or mixtures thereof.

The molecular weight of the surface treatment agent is preferably 100-600, more preferably 150-500, and still more preferably 200-450. Among them, it is preferable to use two or more kinds of surface treatment agents having different molecular weights. When the surface of the glass yarn is treated with two or more surface treatment agents having different molecular weights, the density of the surface treatment agent on the surface of the glass cloth increases, and the reactivity with the matrix resin tends to increase.

[Manufacturing method of glass cloth] The manufacturing method of the glass cloth of the present embodiment is not particularly limited, but for example, a method including a weaving step of weaving a glass yarn to obtain a glass cloth, and a fiber opening of opening the glass yarn of the glass cloth can be exemplified. step. In addition, if necessary, there may be a de-paste step for removing the sizing agent attached to the glass yarn attached to the glass cloth, and a surface treatment step using a surface treatment agent or the like.

The weaving method is not particularly limited as long as the weft and the warp are knitted so as to have a specific knitting structure. Moreover, it does not specifically limit as a fiber opening method, For example, the method of opening a fiber by water jet (high pressure water fiber opening), a vibration washer (vibro washer), ultrasonic water, a rolling press, etc. is mentioned. Furthermore, it does not specifically limit as a desizing method, For example, the method of heating and removing a sizing agent is mentioned. Moreover, as a surface treatment method, the method of making a surface treatment agent contact a glass cloth, and drying, etc. are mentioned. Furthermore, the contact between the surface treatment agent and the glass cloth can be exemplified by the method of dipping the glass cloth in the surface treatment agent, or by using a roll coater, a die coater, or a gravure coater to coat the surface of the glass cloth. Methods of treating agents, etc. It does not specifically limit as a drying method of a surface treatment agent, For example, the drying method using hot air drying or an electromagnetic wave is mentioned.

[prepreg] The prepreg of the present embodiment includes the glass cloth described above, and the matrix resin composition impregnated in the glass cloth. The prepreg with the above-mentioned glass cloth is less likely to cause a decrease in strength, and becomes the one with a higher yield of the final product. In addition, since it is excellent in dielectric properties and moisture absorption resistance, it is also possible to provide a printed circuit board with little variation in dielectric constant under the influence of the use environment, especially in a high-humidity environment.

The prepreg of this embodiment can be conventionally produced. For example, it can be produced by a method of impregnating the glass cloth of the present embodiment with a varnish obtained by diluting a matrix resin such as epoxy resin with an organic solvent, and then volatilizing the organic solvent in a drying furnace to make the thermosetting The resin is hardened to a B-stage state (semi-hardened state).

As the matrix resin composition, in addition to the above-mentioned epoxy resins, bismaleimide resins, cyanate ester resins, unsaturated polyester resins, polyimide resins, BT (polybismaleimide triazine, Thermosetting resins such as alkenediimide triazine) resin and functionalized polyphenylene ether resin; polyphenylene ether resin, polyether imide resin, liquid crystal polymer (LCP) of wholly aromatic polyester, polybutadiene , fluororesin and other thermoplastic resins; and their mixed resins, etc. From the viewpoint of improving dielectric properties, heat resistance, solvent resistance, and press moldability, resins obtained by modifying thermoplastic resins with thermosetting resins can also be used as the matrix resin composition.

In addition, the matrix resin composition may also include in the resin: inorganic fillers such as silicon dioxide and aluminum hydroxide; flame retardants such as bromine-based, phosphorus-based, metal hydroxides; other silane coupling agents; thermal stabilizers; Static agents; UV absorbers; pigments; colorants; lubricants, etc.

[A printed circuit board] The printed wiring board of this embodiment is equipped with the said glass cloth. The printed circuit board of this embodiment is less likely to cause a decrease in strength and has a higher yield rate of the final product. In addition, since it is excellent in dielectric properties and excellent in moisture absorption resistance, the effect of the influence of the use environment, especially the change of the dielectric constant in a high-humidity environment, is small.

In addition, the above-mentioned various measurement values were measured according to the measurement method described in the following Example, unless otherwise specified. [Example]

Hereinafter, the present invention will be described more specifically using Examples and Comparative Examples. The present invention is not limited in any way by the following examples.

[Properties of glass cloth] The physical properties of the glass cloth, specifically the thickness of the glass cloth, the diameter of the filaments constituting the warp and the weft, the number of filaments, and the weaving density of the warp and the weft (weaving density) were measured in accordance with JIS R3420.

[Weight reduction factor] The weight reduction coefficient was measured according to the following procedure. First, put the glass cloth pulled out from the middle roll into a dryer at 105℃±5℃ for 60 minutes, then move the glass cloth to the dryer and let it cool until room temperature. After standing to cool, weigh the glass cloth in units of 0.1 mg or less (glass cloth weight a). Next, the glass cloth was heated at 380° C. for 2 hours, and then the glass cloth was moved to a desiccator and left to cool until room temperature. After standing to cool, the glass cloth was weighed in units of 0.1 mg or less (glass cloth weight b after heat treatment). Then, the weight reduced by the heat treatment was obtained, and the weight reduction ratio (%) was calculated from the following formula (2). Weight reduction ratio (%)＝(a－b)/a×100・・・(2)

Then, the diameter of the monofilament was measured according to the B method of JIS R3420, and the value of 1/2 was taken as the radius of the monofilament. In addition, although the diameter of the cross section of 25 filaments is randomly measured in the B method of JIS R3420, the diameter of all the monofilaments constituting the glass yarn (multifilament) is measured here, and the average value of the filament diameter is obtained. The weight reduction coefficient was calculated by the following formula (1) using the weight reduction ratio (%) and the average radius (μm) of the glass filaments. Weight reduction factor = weight reduction ratio (%) × average radius of glass fiber (μm)・・・(1)

[elasticity coefficient] Regarding the elastic coefficient, the elastic coefficient of the glass yarn was measured by the pulse echo superposition method using a glass block as a test piece.

[Dielectric constant of glass yarn] The glass yarn was melted to prepare a block glass test piece with a length of about 50 mm and a width of about 1.5 mm, and the measurement was carried out using a cavity resonator. The test piece was dried in an oven at 105°C±2°C for 2 hours, and then left for 96 hours in a constant temperature chamber at 23±2°C and relative humidity of 50±5%, and the dielectric constant at 10 GHz was measured.

Furthermore, the measurement device used a network analyzer (N5230A, manufactured by Agilent Technologies, Inc.) and a cavity resonator (Cavity Resornator CP series) manufactured by Kanto Electronics Application Development Co., Ltd. at 23±2°C and relative humidity of 50±5%. measured in the environment.

[The composition of glass cloth] The composition of the glass cloth was measured by ICP (inductively coupled plasma) emission spectrometry. Specifically, regarding the Si content and B content, the weighed glass cloth sample can be decomposed under pressure with sodium hydroxide, dissolved with dilute nitric acid, and filtered, and the insoluble components can be dissolved with sodium carbonate, and the filtrates can be combined and determined. The content was obtained by measuring the obtained sample by ICP emission spectrometry.

In addition, Fe content, Al content, Ca content, Ma content are after heating and decomposing the weighed glass cloth sample with perchloric acid, nitric acid, hydrochloric acid and hydrogen fluoride, then heating and dissolving with dilute aqua regia, and then filtration and separation, and the filtrate is fixed to volume. , the insoluble components are heated and decomposed with sulfuric acid, nitric acid, hydrochloric acid and hydrogen fluoride, and then the solution is determined, and the obtained sample is measured by ICP emission spectrometry. Furthermore, as an ICP emission spectrometer, PS3520VDD II manufactured by Hitachi High-Tech Science was used.

Furthermore, the F content is obtained by burning the weighed glass cloth sample in a tubular electric furnace, absorbing the generated gas into the absorbing solution, and measuring the fluoride ion (F ⁻ ) with an ion chromatograph for the solution. out the content in the sample. In addition, the combustion apparatus used the automatic sample combustion apparatus (AQF-2100S) manufactured by Mitsubishi Chemical Analytech, and the measuring apparatus used the ion chromatograph ICS-1500 manufactured by Thermo Fisher Scientific.

[Strength Reduction Confirmation Test] Using the glass cloths obtained in the Examples and Comparative Examples, prepregs were produced under the following conditions, and it was evaluated whether the strength was sufficient. While continuously pulling out and conveying the glass cloth, the glass cloth is dipped in the varnish and passed through the slit to adjust the coating amount of the varnish. Then, the prepreg was obtained by drying it in a drying furnace at 120°C. In addition, the varnish system used contains 65 parts by mass of methacrylated polyphenylene ether, 35 parts by mass of triallyl isocyanurate, 10 parts by mass of hydrogenated styrene-based thermoplastic elastomer, 25 parts by mass of brominated flame retardant, spherical 65 parts by mass of silicon oxide, 1 part by mass of organic peroxide, and 210 parts by mass of toluene.

With respect to the glass cloths obtained in the respective Examples and Comparative Examples, 10 pieces of the product rolls of 2000 m were each rolled, and the production of the prepreg was carried out by the above-mentioned method. Based on the production results, the strength reduction was confirmed according to the following evaluation criteria. ⊚: The glass cloth is not broken, and the prepreg can be produced using a roll of 10 glass cloths. The glass cloth was judged to be excellent in productivity and workability. : During the production process of the prepreg, one glass cloth roll breaks, but the remaining 9 rolls can be used to make the prepreg without breaking. It was judged to be a glass cloth with practical strength. △: During the production of the prepreg, 2 to 3 rolls of glass cloth were broken, but the remaining rolls could be produced without breaking. It is judged that glass cloth with improved strength is required. ×: During the production process of the prepreg, the rolls of 4 or more glass cloths were broken.

[Dielectric Constant and Dielectric Loss Factor of Laminates] The prepreg obtained in the strength reduction confirmation test was superimposed by a predetermined number so that the thickness of the laminate would be about 1 mm, and copper foils (manufactured by Furukawa Electric Co., Ltd.) were superimposed on both sides of the superimposed prepreg. , thickness 18 μm, GTS-MP foil), in this state, carry out vacuum pressure, thereby obtain copper foil laminated board. Then, from the above-mentioned copper foil laminate, the copper foil was removed by etching to obtain a laminate.

From the obtained laminate, a test piece with a length of about 50 mm and a width of about 1.5 mm was cut out so that the warp of the glass cloth became the long side, and was used as a test piece for the electrical property test. After drying the obtained test piece in an oven at 105°C ± 2°C for 2 hours, the dielectric constant and dielectric dissipation factor at 10 GHz were measured under the standard conditions and high humidity conditions shown below. Standard conditions: The measurement is carried out after standing for 96 hours in a constant temperature room at 23±2℃ and relative humidity of 50±5% High humidity conditions: measure after 96 hours in a constant temperature room at 40±2℃ and 85±5% relative humidity

Furthermore, the measurement device used a network analyzer (N5230A, manufactured by Agilent Technologies) and a cavity resonator (Cavity Resornator CP series) manufactured by Kanto Electronics Application Development Co., Ltd. The measurement itself was performed at 23±2°C and a relative humidity of 50°C. Under the environment of ±5%. Each measurement was repeated 5 times using 5 test pieces cut out, and the average value was used as the value of the dielectric constant and the dielectric tangent.

[Example 1] Using an air-jet loom, a low-dielectric glass yarn with an average filament diameter of 4.0 μm and 50 filaments (dielectric constant 4.8) was woven, and the weaving density of warp and weft was 94/25 mm and 14 μm, respectively. of glass cloth. Then, it was degummed by heating to obtain an intermediate roll of glass cloth with a width of 1280 mm and a length of 2000 m.

Using the obtained intermediate roll of glass cloth, the glass cloth was continuously drawn from the intermediate roll of glass cloth and conveyed, the glass cloth was immersed in a treatment liquid containing a silane coupling agent, and the coating of the silane coupling agent was adjusted by squeezing the liquid. After measuring, it is temporarily dried. Next, the fiber was opened by high-pressure water spray, dried, and wound into a roll to obtain a product roll of glass cloth. Furthermore, the application of the above-mentioned silane coupling agent and the fiber-opening treatment were carried out continuously for 10 rolls. The composition of the obtained glass cloth is shown in Table 1.

[Examples 2 to 11] A roll of glass cloth was obtained in the same manner as in Example 1 except that the composition of the glass yarn was different. The composition of the obtained glass cloth is shown in Table 1.

[Example 12] Except using the same low-dielectric glass yarn as in Example 2, and reducing the degree of fiber opening by reducing the strength of the high-pressure water spray in the fiber opening treatment, the glass cloth was obtained in the same manner as in Example 2. roll.

[Example 13] Except using the same low-dielectric glass yarn as in Example 2, and increasing the degree of fiber opening by increasing the strength of the high-pressure water spray in the fiber opening treatment, the glass cloth was obtained in the same manner as in Example 2. roll.

[Example 14] Low-dielectric glass yarn (dielectric constant 4.8) with an average filament diameter of 5.0 μm and 100 filaments was woven, and the weaving densities of warp and weft were set to 69 pieces/25 mm to produce glass cloth, except that , a roll of glass cloth was obtained in the same manner as in Example 1. The thickness of the obtained glass cloth is 30 μm, and the composition is shown in Table 1.

[Example 15] A roll of glass cloth was obtained in the same manner as in Example 14, except that the weaving densities of the warp and weft were 55 pieces/25 mm, respectively. The thickness of the obtained glass cloth is 30 μm, and the composition is shown in Table 1.

[Example 16] Low-dielectric glass yarn (dielectric constant 4.8) with an average filament diameter of 7.0 μm and 200 filaments was woven, and the weaving densities of warp and weft were set to 60/25 mm and 57/25 mm, respectively. A glass cloth roll was obtained in the same manner as in Example 1 except for this. The thickness of the obtained glass cloth is 92 μm, and the composition is shown in Table 1.

[Comparative Examples 1 to 6] A roll of glass cloth was obtained in the same manner as in Example 1 except that the composition of the glass yarn was different. The composition of the obtained glass cloth is shown in Table 1.

[Reference Example 1] A roll of glass cloth was obtained in the same manner as in Example 1 except that a glass yarn composed of E glass was used.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 glass cloth Composition (mass %) Si (SiO ₂ conversion) 51.7 51.8 51.6 52.0 51.4 51.9 52.2 51.9 52.1 52.0 B (B ₂ O ₃ conversion) 23.7 23.6 23.6 23.6 23.7 23.7 23.8 23.7 23.3 23.4 Al (Al ₂ O ₃ conversion) 14.3 14.5 14.4 14.4 14.5 14.4 14.6 14.5 14.4 14.4 Ca (CaO conversion) 8.0 8.1 8.0 8.0 8.0 8.1 8.0 8.1 8.0 8.0 Mg (MgO conversion) 0.3 0.2 0.2 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Fe (Fe ₂ O ₃ conversion) 0.32 0.36 0.33 0.33 0.33 0.33 0.23 0.24 0.24 0.17 F (F ₂ conversion) 0.02 0.02 0.12 0.24 <0.005 0.47 0.02 0.12 0.24 0.02 Thickness (μm) 14 14 14 14 14 14 14 14 14 14 Elasticity coefficient 61 61 61 61 61 61 61 61 61 61 Weight reduction factor 0.34 0.34 0.34 0.34 0.33 0.34 0.34 0.34 0.34 0.34 Evaluation results Strength of glass cloth (prepreg coating test) ◎ ◎ ◎ ◎ ◎ Dielectric constant Standard conditions 3.1 3.1 3.1 3.1 3.1 3.1 3.1 3.1 3.1 3.1 high humidity conditions 3.1 3.1 3.1 3.1 3.1 3.1 3.1 3.1 3.1 3.1 Dielectric Dissipation Factor Standard conditions 0.0031 0.0031 0.0031 0.0031 0.0031 0.031 0.0031 0.0031 0.0031 0.0031 high humidity conditions 0.0038 0.0038 0.0038 0.0039 0.040 0.041 0.0038 0.0039 0.0039 0.0039

[Table 2] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 11 Reference Example 1 Example 12 Example 13 Example 14 Example 15 Example 16 glass cloth Composition (mass %) Si (SiO ₂ conversion) 51.9 51.8 51.8 51.6 51.0 51.1 51.9 54.4 51.7 51.7 51.6 51.6 51.5 B (B ₂ O ₃ conversion) 23.6 23.6 23.6 23.7 28.8 28.9 23.7 6.3 23.6 23.6 23.8 23.6 23.9 Al (Al ₂ O ₃ conversion) 14.4 14.4 14.5 14.4 14.1 13.3 12.5 14.2 14.5 14.4 14.5 14.6 14.5 Ca (CaO conversion) 8.0 8.0 7.9 8.0 4.1 4.1 7 22.8 8.0 8.0 8.1 8.2 8.1 Mg (MgO conversion) 0.3 0.3 0.3 0.3 1.5 1.3 4.0 0.8 0.2 0.2 0.2 0.2 0.3 Fe (Fe ₂ O ₃ conversion) 0.08 0.43 0.44 0.43 0.20 0.43 0.34 0.42 0.36 0.36 0.24 0.24 0.24 F (F ₂ conversion) 0.02 <0.005 0.02 0.46 <0.005 <0.005 0.02 0.48 0.02 0.02 0.02 0.02 0.02 Thickness (μm) 14 14 14 14 14 14 14 14 15 12 30 30 92 Elasticity coefficient 61 61 61 61 57 57 61 74 61 61 61 61 61 Weight reduction factor 0.34 0.34 0.34 0.34 0.49 0.48 0.33 0.11 0.31 0.38 0.31 0.33 0.21 Evaluation results Strength of glass cloth (prepreg coating test) △ × △ × △ × ◎ ◎ ◎ ◎ ◎ Dielectric constant Standard conditions 3.1 Not rated 3.1 Not rated 3.1 Not rated 3.1 5.1 3.1 3.1 Not rated Not rated Not rated high humidity conditions 3.1 Not rated 3.1 Not rated 3.1 Not rated 3.1 5.1 3.1 3.1 Not rated Not rated Not rated Dielectric Dissipation Factor Standard conditions 0.0031 Not rated 0.0031 Not rated 0.032 Not rated 0.0032 0.0048 0.0031 0.0031 Not rated Not rated Not rated high humidity conditions 0.0039 Not rated 0.0039 Not rated 0.0046 Not rated 0.0044 0.0054 0.0038 0.0039 Not rated Not rated Not rated

All 10 rolls of glass cloth systems of Examples 1 to 4, 7, 12, and 14 to 16 were able to be stably produced without breaking the glass cloth. Moreover, in the glass cloth systems of Examples 5, 6, 8 to 11, and 13, the glass cloth was broken in only one roll, but the remaining nine rolls were stably produced. In addition, although the glass cloth system of Reference Example 1 did not break, it was inferior in electrical properties.

On the other hand, the glass cloths of Comparative Examples 1, 3, and 5 were broken in 2 to 3 rolls. It is not enough to stably supply printed circuit boards using low dielectric glass, and needs to be improved. Furthermore, since the glass cloths of Comparative Examples 2, 4, and 6 were broken continuously in four rolls from the start of coating, the coating test had to be stopped.

Furthermore, as shown in Example 11, it can be seen that when the Mg content is large, the increase in the dielectric tangent under high humidity conditions is large when a laminate is produced. [Industrial Availability]

The present invention has industrial applicability as a low-dielectric glass cloth used for prepregs and the like.

Claims (14)

A glass cloth composed of glass yarns containing a plurality of glass filaments as warps and wefts, and in the following formula (1), the weight reduction ratio derived from the glass component in the heat treatment at 380° C. for 2 hours The weight reduction factor obtained by multiplying the average radius of the glass filaments above is 0.18 or more and 0.45 or less. Weight reduction factor = the above-mentioned weight reduction ratio (%) × the average radius of the above-mentioned glass filaments (μm)・・・(1) The above-mentioned glass cloth The Fe content exceeds 0.1 mass % and is less than 0.4 mass % in terms of Fe ₂ O ₃ . The glass cloth according to claim 1, wherein the Fe content of the glass cloth exceeds 0.2 mass % and is less than 0.4 mass % in terms of Fe ₂ O ₃ . The glass cloth according to claim 2, wherein the Fe content of the glass cloth exceeds 0.3% by mass and less than 0.4% by mass in terms of Fe ₂ O ₃ . The glass cloth according to any one of claims 1 to 3, wherein the F content of the glass cloth exceeds 0.005 mass % and is less than 0.4 mass %. The glass cloth of claim 4, wherein the F content of the glass cloth exceeds 0.005 mass % and is less than 0.2 mass %. The glass cloth of claim 5, wherein the F content of the glass cloth exceeds 0.005 mass % and is less than 0.1 mass %. The glass cloth according to any one of claims 1 to 3, wherein the Si content of the glass cloth is 40-60 mass % in terms of SiO ₂ , and the B content is 15-30 mass % in terms of B ₂ O ₃ . The glass cloth of claim 7, wherein the Al content of the glass cloth is 10-20 mass % in terms of Al ₂ O ₃ , the Ca content is 4-12 mass % in terms of CaO conversion, and the Mg content is 1 in terms of MgO conversion mass % or less. The glass cloth of any one of claims 1 to 3, wherein The elastic modulus of the glass cloth is 50-70 GPa. As in the glass cloth of claim 9, wherein The elastic modulus of the glass cloth is 50 to 63 GPa. The glass cloth of any one of claims 1 to 3, wherein The average diameters of the glass filaments constituting the warp yarns and the weft yarns are independently 3.5 to 5.4 μm. As the glass cloth of any one of claims 1 to 3, its Has a dielectric constant below 5.0 at 1 GHz. A prepreg having: A glass cloth as claimed in any one of claims 1 to 12; and The matrix resin impregnated in the glass cloth. A printed circuit board with With the glass cloth according to any one of claims 1 to 12.