JP7011396B2 - Glass cloth, prepreg, and printed wiring board - Google Patents

Description

The present invention relates to glass cloths, prepregs, and printed wiring boards.

At present, along with the high performance and high-speed communication of information terminals such as smartphones, the printed wiring boards used are becoming denser and ultrathin, as well as having a low dielectric constant and a low dielectric loss tangent. ..

As the insulating material of this printed wiring board, a laminated board obtained by impregnating a glass cloth with a thermosetting resin such as an epoxy resin (hereinafter referred to as "matrix resin") and laminating a prepreg obtained by laminating and heat-pressing curing. Is widely used. While the dielectric constant of the matrix resin used for the above-mentioned high-speed communication board is about 3, the dielectric constant of a general E glass cloth is about 6.7, which causes a problem of high dielectric constant at the time of a laminated board. It is becoming apparent. The signal transmission loss is determined by Edward A. Wolff equation: As shown by the transmission loss ∝√ε × tanδ, it is known that the material having a smaller dielectric constant (ε) and dielectric loss tangent (tanδ) is improved.

Therefore, low dielectric constant glass cloths such as D glass, NE glass, and L glass having a glass composition different from that of E glass have been proposed (see, for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 5-170483 Japanese Unexamined Patent Publication No. 2009-263569 Japanese Unexamined Patent Publication No. 2009-19150 Japanese Unexamined Patent Publication No. 2009-263824

However, in future 5G communication applications and the like, there is still room for improvement in these low dielectric constant glass cloths from the viewpoint of achieving sufficient transmission speed performance.
Here, it is conceivable to further reduce the dielectric constant and the dielectric loss tangent by setting the amount of SiO ₂ in the glass composition to be approximately 100%. However, when the amount of SiO ₂ blended is approximately 100%, the bending resistance of the glass filament tends to be significantly lowered, and the glass filament may be cracked or broken.
The broken or broken glass filaments contribute to the fluffing of the glass cloth. In the case of glass filaments in which the amount of SiO ₂ blended is increased, the fluffing portion tends to stand vertically, so that the fluffing portion is more likely to become apparent.
Further, when a substrate (“board” is a concept including a prepreg, a printed wiring board, or a laminated plate thereof, etc.) is manufactured, if the fluffed portion collides with the conductive layer, the interlayer insulation becomes poor. There was a case. That is, there is still room for improvement from the viewpoint of realizing a substrate having excellent interlayer insulation reliability.

The present invention has been made in view of the above problems, and is a glass cloth capable of producing a substrate having a low dielectric constant and excellent interlayer insulation reliability, a prepreg using the glass cloth, and a printed wiring board. The purpose is to provide a board.

As a result of studies for solving the above-mentioned problems, the present inventors have found that a predetermined glass cloth can solve the above-mentioned problems, and have completed the present invention.

That is, the present invention is as follows.
[1]
A glass cloth made by weaving glass threads composed of a plurality of glass filaments as warps and wefts.
The average filament diameter of the warp and the glass filament constituting the weft is 3 μm to 10 μm.
The number of glass filaments of the warp and weft is 20 to 300, and the number of glass filaments is 20 to 300.
The driving densities of the warp and weft are independently 20 to 140 threads / inch, respectively.
The thickness of the glass cloth is 8 μm to 100 μm.
The number of fluffs with a length of 1 mm or more observed when a tension of 100 N / 1000 mm is applied by Roll-to-Roll is 10 pieces / m ² or less.
Glass cloth.
[2]
The glass cloth according to [1], wherein the number of glass filaments arranged in the Z direction in the warp and weft is 8 or less independently.
[3]
The glass cloth according to [1] or [2], wherein the ignition loss value of the glass cloth is 0.2% by mass or more and 1.0% by mass or less.
[4]
The glass cloth according to any one of [1] to [3], wherein the SiO ₂ composition amount of one of the warp and weft is 98% by mass or more and 100% by mass or less.
[5]
The glass cloth according to any one of [1] to [4], wherein the SiO ₂ composition amount of one of the warp and weft is 98% by mass or more and 99.99% by mass or less.
[6]
The glass cloth according to any one of [1] to [5], wherein the glass cloth has a dielectric constant of 4.3 or less.
[7]
The glass cloth according to any one of [1] to [6], wherein the surface of the glass thread is treated with a silane coupling agent.
[8]
The gluing step of adhering the adhesive to the glass thread by 2% by mass or more and 10% by mass or less,
A weaving step of weaving a glass cloth using the glass yarn obtained by the gluing step as a warp and a weft,
A degluing step of removing the adhesive adhering to the glass cloth obtained by the weaving step and reducing the amount of the adhesive adhering to 0.1% by mass or less.
A method for manufacturing glass cloth, including.
[9]
The method for producing a glass cloth according to [8], wherein the gluing step is performed a plurality of times before the degluing step.
[10]
The method for producing a glass cloth according to [8] or [9], wherein the adhesive comprises one or more selected from the group consisting of starch, polyvinyl alcohol, polyethylene oxide, polyester, and polyamide.
[11]
The glass cloth according to any one of [1] to [7] and
A matrix resin impregnated in the glass cloth, and the like.
Pre-preg.
[12]
A printed wiring board having the prepreg according to [11].

According to the present invention, it is possible to provide a glass cloth capable of producing a substrate having a low dielectric constant and excellent interlayer insulation reliability, a prepreg using the glass cloth, and a printed wiring board.

Hereinafter, embodiments of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail, but the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof. Is.

〔Glass cloth〕
The glass cloth of the present embodiment is a glass cloth obtained by weaving a glass thread composed of a plurality of glass filaments as a warp and a weft.
Further, in the glass cloth of the present embodiment, the average filament diameter of the warp and the glass filament constituting the weft is 3 μm to 10 μm, and the number of glass filaments of the warp and the warp is 20 to 300. The warp and weft driving densities are independently 20 to 140 lines / inch, the thickness of the glass cloth is 8 μm to 100 μm, and the number of fluffs having a length of 1 mm or more is 10. It is less than / m ² .

As mentioned above, broken or broken glass filaments contribute to the fluffing of the glass cloth. Such fluffing may occur in the washing and opening steps after the surface treatment of the glass cloth. Further, in prepreg applications, fluffing may occur during the processing (including the case where the originally small fluff changes to a large fluff).

As a result of diligent studies, the present inventors have found that the glass cloth of the present embodiment, that is, a certain size or more observed when a constant tension is applied (rather than observing in a non-tensioned state). When a glass cloth that satisfies a certain condition that the number of fluffs is a certain number or less is selected and used, it is possible to suppress the fluffs from colliding with the conductive layer when manufacturing the substrate, and eventually the interlayer insulation reliability is improved. We have found that an excellent substrate can be realized. The details of the mechanism by which glass cloth that meets certain conditions realizes a substrate with excellent interlayer insulation reliability are not detailed, but in the process of threading, impregnation, pressing, cooling / curing, etc., when manufacturing the substrate, While various external forces applied to the glass cloth are thought to be the cause of the increase in fluff, such increase is suppressed or shrinkage in the cooling / curing process in glass cloth with a small fluffing angle or degree under constant tension. Since the angle of fluffing decreases in the process, it is speculated that the amount of glass in contact with the conductive layer may decrease as a result of the substrate state.

The number of fluffs of 1 mm or more can be evaluated by the method described in Examples.
The number of fluffs is preferably 9 / m ² or less, and more preferably 8 / m ² or less. Further, the lower limit of the number of fluffs is ideally 0 fluff / m ² , but it may be 1 fluff / m ² or more, and may be 2 fluff / m ² or more.
The number of fluffs having a length of 1 mm or more can be reduced to 10 / m ² or less by using, for example, the warps and wefts obtained by adhering a predetermined amount of adhesive as the warps and wefts constituting the glass cloth. Can be adjusted.

[Glass filament composition]
In the present embodiment, a glass thread containing a glass filament having a SiO ₂ composition amount of 98 to 100% by mass (hereinafter, also referred to as “glass filament A”) and a SiO ₂ composition amount of 45 to 60% by mass. A glass thread containing a glass filament having a B ₂ O ₃ composition of 15 to 30% by mass (hereinafter, also referred to as “glass filament B”) can be preferably used.
In the glass cloth of the present embodiment, one of the warp and the weft is a glass thread made of a glass filament A, and the other of the warp and the weft is a glass thread made of a glass filament B; both the warp and the weft are An embodiment of a glass thread made of glass filament A; one of the warp and weft is a glass thread made of glass filament A and glass filament B, and the other of the warp and weft is a glass thread or glass filament made of glass filament A. The embodiment is a glass yarn made of B; and the embodiment in which both the warp and weft are glass yarns made of glass filament A and glass filament B;
Among these aspects of the glass cloth, one of the warp and weft is a glass thread made of glass filament A, and the other of the warp and weft is a glass thread made of glass filament B, and the warp and weft. It is preferable that both are glass threads made of glass filament A.

[Glass filament A]
The SiO ₂ composition amount of the glass filament A is preferably 98 to 100% by mass, more preferably 98 to 99.99% by mass, and further preferably 98 to 99.95% by mass. When the SiO ₂ composition amount is 98% by mass or more, the dielectric constant and the dielectric loss tangent tend to be further reduced. Further, when the SiO ₂ composition amount is 98% by mass or more, air contamination during glass melt spinning can be suppressed, and the generation of hollow fibers can be suppressed. By reducing the number of hollow fibers, the insulation reliability of the substrate tends to be further improved. Further, when the SiO ₂ composition amount is 100% by mass or less, the bending resistance and brittleness of the glass yarn tend to be further improved. As a result, the drill workability of the substrate is further improved, and the glass thread breakage is less likely to occur at the time of opening the fiber after the processing of the glass cloth and at the time of washing with water, and the amount of fluff of the glass cloth tends to decrease. .. By using such a glass cloth, the dielectric constant is further lowered, the insulation reliability is improved due to the reduction of hollow threads, the insulation reliability is improved due to the improvement of the drilling workability of the substrate, and the fluffing is reduced. It is possible to improve the insulation reliability (prevention of plating penetration, protrusion failure, interlayer insulation failure, etc.). The amount of SiO ₂ composition can be adjusted according to the amount of raw material used for producing the glass filament.

Further, the glass filament A may have other compositions other than SiO ₂ . Other compositions are not particularly limited, and examples thereof include Al ₂ O ₃ , CaO, MgO, B ₂ O ₃ , TIO ₂ , Na ₂ O, K ₂ O, Sr ₂ O ₃ , Fe ₂ O ₃ and the like. Be done.

[Glass filament B]
The SiO ₂ composition amount of the glass filament B is 45 to 60% by mass, preferably 50 to 60% by mass, and more preferably 51 to 56% by mass. The B ₂ O ₃ composition of the glass filament B is 15 to 30% by mass, preferably 20 to 30% by mass, and more preferably 21 to 25% by mass. When the SiO ₂ composition amount is 60% or less and the B ₂ O ₃ composition amount is 15% by mass or more, the glass melt viscosity is lowered and the glass yarn is easily pulled, so that the generation of hollow yarn can be suppressed. Also, the dielectric constant decreases. Further, when the SiO ₂ composition amount is 45% or more and the B ₂ O ₃ composition amount is 30% by mass or less, the hygroscopicity is further improved when the surface treatment is applied. On the other hand, when the B ₂ O ₃ composition amount is less than 15% by mass, the number of hollow yarns increases, and the insulation reliability decreases accordingly. Further, when the B ₂ O ₃ composition amount is further reduced to the E glass composition amount, the number of hollow yarns tends to decrease, but the dielectric constant increases. Further, if the B ₂ O ₃ composition amount exceeds 30% by mass, the moisture absorption amount increases, and thus the insulation reliability decreases. The B ₂ O ₃ composition amount can be adjusted according to the amount of the raw material used for producing the glass filament.
The composition of the glass filament B may be a known glass composition such as E glass (non-alkali glass), NE glass, L glass, D glass, S glass, and T glass, and among them, NE glass and L. Glass is preferred.

Further, the glass filament B may have other compositions in addition to SiO ₂ and B ₂ O ₃ . Other compositions are not particularly limited, and examples thereof include Al ₂ O ₃ , CaO, MgO, TiO ₂ , Na ₂ O, K ₂ O, Sr ₂ O ₃ , Fe ₂ O ₃ and the like.

The Al ₂ O ₃ composition amount in the glass filament B is preferably 11 to 16% by mass, more preferably 12 to 16% by mass. When the Al ₂ O ₃ composition amount is within the above range, the productivity of the yarn tends to be further improved.

The CaO composition content in the glass filament B is preferably 4 to 8% by mass, more preferably 6 to 8% by mass. When the CaO composition amount is within the above range, the productivity of the yarn tends to be further improved.

[Driving density]
The driving densities of the warp and weft constituting the glass cloth are independently 20 to 140 threads / inch, preferably 30 to 130 threads / inch, and more preferably 40 to 120 threads / inch.

〔thickness〕
The thickness of the glass cloth is 8 μm to 100 μm, preferably 15 μm to 90 μm, and more preferably 20 μm to 80 μm.

[Cloth weight (Metsuke)]
The cloth weight (weighting) of the glass cloth is preferably 6 to 100 g / m ² , and more preferably 7 to 90 g / m ² .

[Woven structure]
The woven structure of the glass cloth is not particularly limited, and examples thereof include woven structures such as plain weave, nanako weave, satin weave, and twill weave. Of these, a plain weave structure is more preferable.

[Average filament diameter of glass filament]
The average filament diameters of the glass filaments constituting the warp and weft are independently 3 to 10 μm, preferably 3.5 to 9.5 μm. When the average filament diameter of the glass filament is within the above range, the processability tends to be further improved when the obtained substrate is machined by a mechanical drill. In particular, setting the average filament diameter of the glass filament to 9.5 μm or less means that the area of contact between the matrix resin and the glass filament per unit volume increases, so the ignition loss value is set to 0.2% by mass or more. This is preferable because the effects described below tend to be more pronounced. When the warp or weft is a glass thread made of glass filament A or B, the average filament diameter is the average filament diameter of the glass filaments A or B constituting the glass thread, and the warp or weft is glass. In the case of a glass thread composed of filaments A and B, the average filament diameter is the average filament diameter of the glass filaments A and B constituting the glass thread.

In particular, the average filament diameter of the glass filament A is preferably 4 to 10 μm, more preferably 6 to 10 μm, and even more preferably 7.5 to 10 μm. When the average filament diameter of the glass filament A is 4 μm or more, the yarn breakage of the glass filament A is further suppressed, the amount of fluffing of the glass cloth is reduced, and the insulation reliability derived from the reduction of fluffing tends to be further improved. .. Further, since the area of contact between the matrix resin and the glass filament per unit volume increases when the average filament diameter of the glass filament A is 10 μm or less, the ignition loss value is set to 0.2% by mass or more, which will be described later. The effect tends to be more pronounced.

The average filament diameter of the glass filament B is preferably 3 to 9 μm, more preferably 4 to 8 μm, and even more preferably 5 to 7 μm. When the average filament diameter of the glass filament B is 3 μm or more, the processability of the obtained substrate tends to be further improved. Since the area of contact between the matrix resin and the glass filament per unit volume increases when the average filament diameter of the glass filament B is 9 μm or less, the effect described later by setting the ignition loss value to 0.2% by mass or more can be obtained. It tends to be more expressed.

[Number of filaments of glass filament]
The number of filaments of the glass filaments constituting the warp and weft is independently 20 to 300, preferably 20 to 200. When the number of filaments of the glass filament is within the above range, the processability tends to be further improved when the obtained substrate is machined by a mechanical drill. When the warp or weft is a glass thread made of glass filament A or B, the number of filaments is the number of glass filaments A or B constituting the glass thread, and the warp or weft is glass filament A or In the case of a glass thread made of B, the number of filaments is the total number of glass filaments A and B constituting the glass thread.

In particular, when the warp and / or weft is a glass yarn made of glass filament A, the number of filaments of the glass filament A is preferably 20 to 250, more preferably 50 to 200, still more preferable. Is 75 to 150. When the number of filaments of the glass filament A is 20 or more, the yarn breakage of the glass filament A is further suppressed, the amount of fluffing of the glass cloth is reduced, and the insulation reliability resulting from the reduction of fluffing tends to be further improved. .. Further, since the number of filaments of the glass filament A is 250 or less, there is a tendency that a finer glass yarn can be realized while suppressing fluffing in consideration of the filament diameter.

When the warp or weft is a glass yarn made of glass filament B, the number of filaments of the glass filament B is preferably 50 to 300, more preferably 100 to 275, and further preferably 150. ~ 250 pieces. When the number of filaments of the glass filament B is 50 or more, the processability of the obtained substrate tends to be further improved. When the number of filaments of the glass filament B is 300 or less, there is a tendency that a finer glass thread can be realized in consideration of the filament diameter.

[Number of filaments in the Z direction]
The number of filaments in the Z direction of the warp and weft of the glass cloth is preferably 8 or less, more preferably 7 or less, and further preferably 6 or less, respectively. When the number is 8 or less, the drill workability can be greatly improved. In particular, when a glass thread made of glass filament A is used, the improvement effect of 8 or less is great. Further, when the number is 8 or less, the thick portion is locally eliminated in the plane of the glass cloth, and the effect of improving the interlayer insulation can be further enhanced. The number of filaments in the Z direction can be obtained from the maximum value by observing any 20 yarn bundles with an electron microscope.

〔surface treatment〕
The glass yarn (including the glass filament) of the glass cloth is surface-treated with a silane coupling agent, preferably a silane coupling agent having an unsaturated double bond group (hereinafter, also simply referred to as “silane coupling agent”). It is preferable that the glass is saturated. By using a silane coupling agent having an unsaturated double-bonding group, the reactivity with the matrix resin is further improved, and the hydrophilic functional group is less likely to be generated after the reaction with the matrix resin, and the insulation reliability is further improved.

The silane coupling agent is not particularly limited, and examples thereof include compounds represented by the following general formula (1). By using such a silane coupling agent, the hygroscopicity is further improved, and as a result, the insulation reliability tends to be further improved. In particular, by using a silane coupling agent having an unsaturated double bond group, the plating liquid penetration property, insulation reliability, and fluffing after drilling of a glass cloth having a SiO ₂ composition amount of 98 to 100% by mass are used. The quality can be improved.
X (R) _3-n SiY _n ... (1)
(In the formula, X is an organic functional group having at least one of an amino group and an unsaturated double bond group, Y is an independently alkoxy group, and n is 1 or more and 3 or less. R is a group independently selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.)

X is an organic functional group having at least one of an amino group and an unsaturated double-bonding group, more preferably an organic functional group having three or more, and an amino group and an unsaturated double-bonding group. It is more preferable that the organic functional group has at least four or more of the above. When X is such a functional group, hygroscopicity tends to be further improved. The organic functional group having one or more unsaturated double bond groups represented by X is not particularly limited, and examples thereof include a vinyl group, an allyl group, a vinylidene group, an acryloxy group, and a methacryloxy group.

Any form can be used as the above-mentioned alkoxy group, but an alkoxy group having 5 or less carbon atoms is preferable for stable treatment on the glass cloth.

The silane coupling agent that can be specifically used is not particularly limited, but for example, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane and its hydrochloride, N-β- (N). -Vinylbenzylaminoethyl) -γ-aminopropylmethyldimethoxysilane and its hydrochloride, N-β- (N-di (vinylbenzyl) aminoethyl) -γ-aminopropyltrimethoxysilane and its hydrochloride, N-β -(N-di (vinylbenzyl) aminoethyl) -N-γ- (N-vinylbenzyl) -γ-aminopropyltrimethoxysilane and its hydrochloride, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloxypropyl Known substances such as trimethoxysilane, methacryloxyoctyltrimethoxysilane, and acryloxypropyltrimethoxysilane can be mentioned. The silane coupling agent tends to have excellent reactivity with the glass thread (glass filament) of the glass cloth and the matrix resin of the substrate, particularly the radical polymerization type resin. Therefore, there is a tendency that it is possible to suppress a decrease in insulation reliability due to the resin and the glass cloth being easily peeled off at the interface, and it is possible to suppress a decrease in insulation reliability due to the plating liquid permeating into the glass cloth.

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 preferable to use a silane coupling agent having two or more kinds of unsaturated double bond groups having different molecular weights. By treating the surface of the glass yarn with two or more kinds of silane coupling agents having different molecular weights, the density of the treatment agent on the glass surface tends to be high, and the reactivity with the matrix resin tends to be further improved. The amount of glass cloth treated with the silane coupling agent can be estimated by the following ignition loss value.

[Ignition weight loss value of glass cloth]
The ignition loss value of the glass cloth is preferably 0.2% by mass or more, more preferably 0.25% by mass or more, and further preferably 0.30% by mass or more. The upper limit of the ignition loss value of the glass cloth is preferably 1.0% by mass or less, more preferably 0.90% by mass or less, and further preferably 0.8% by mass or less. When the ignition loss value of the glass cloth is 0.2% by mass or more, the plating liquid penetration property, insulation reliability, and fluffing of the glass cloth having a SiO ₂ composition amount of 98 to 100% by mass after drilling are performed. The quality can be improved. Further, the hygroscopicity is further improved, and the deterioration of the insulation reliability due to the hygroscopicity can be further suppressed. Further, when the ignition loss value of the glass cloth is 1.0% by mass or less, the resin permeability to the glass cloth is further improved, and as a result, the insulation reliability is further improved.

The "ignition weight loss value" of the glass cloth referred to here can be measured according to the method described in JIS R3420. That is, first, the glass cloth is placed in a dryer at 110 ° C. and dried for 60 minutes. After drying, transfer the glass cloth to a desiccator, leave it for 20 minutes, and allow it to cool to room temperature. After allowing to cool, weigh the glass cloth in units of 0.1 mg or less. Next, the glass cloth is heated in a muffle furnace at 625 ° C. for 20 minutes. After heating in a muffle furnace, transfer the glass cloth to a desiccator, leave it for 20 minutes, and allow it to cool to room temperature. After allowing to cool, weigh the glass cloth in units of 0.1 mg or less. The amount of glass cloth treated with the silane coupling agent is defined by the ignition loss value obtained by the above measurement method.

[Dielectric constant of glass cloth]
The dielectric constant of the glass cloth is preferably 4.3 or less, more preferably 4.1 or less, and further preferably 3.9 or less. The dielectric constant of the glass cloth can be measured by the method described in Examples.

[Manufacturing method of glass cloth]
In the method for producing a glass cloth of the present embodiment, a gluing step of adhering a glue to the glass thread by 2% by mass or more and 10% by mass or less, and the glass thread obtained by the gluing step are used as warp and weft to obtain a glass cloth. It includes a weaving step of weaving and a degluing step of removing the glue adhering to the glass cloth obtained by the weaving step so that the amount of the glue adhered is 0.1% by mass or less.
Further, in the method for producing a glass cloth of the present embodiment, the gluing step may be performed a plurality of times before the degluing step.

By the above gluing step, a glass yarn having an adhesive amount of 2% by mass or more and 10% by mass or less can be obtained. In the gluing step, for example, the adhesive can be attached to the glass thread by applying an aqueous solution of the adhesive to the glass thread. As a method of applying the aqueous solution of the adhesive to the glass thread, for example, a method of storing the aqueous solution of the adhesive in a bath and immersing and passing the glass cloth (hereinafter referred to as "immersion method") is possible.
Further, in order to adjust the adhesion amount of the adhesive, for example, a step of applying an aqueous solution of the adhesive to the glass thread and then squeezing the glass thread to which the adhesive is applied by a squeeze roll or the like may be included.

The concentration of the sizing agent in the aqueous solution of the sizing agent is not particularly limited as long as it can be a glass thread having an adhering amount of the sizing agent of 2% by mass or more and 10% by mass or less, and is preferably 2% by mass or more and 8 by mass. It is 1% by mass or less, more preferably 2% by mass or more and 5% by mass or less, and further preferably 2% by mass or more and 4% by mass or less.

In the degluing step, for example, by heating the glass cloth obtained in the weaving step, the glue adhering to the glass yarn can be removed, and the amount of the glue adhering can be reduced to 0.1% by mass or less. .. The heating temperature in the degluing step may be appropriately adjusted depending on the type of glue used and the like, and is preferably around 400 ° C.

The lower limit of the amount of the adhesive adhered in the gluing step is preferably 2% by mass or more from the viewpoint of stability during weaving and reduction of the number of fluffs. The upper limit of the amount of the adhesive adhered in the gluing step is preferably 10% by mass or less, more preferably 8% by mass, from the viewpoint of improving the resin permeability to the glass cloth and, as a result, improving the insulation reliability. % Or less, more preferably 5% by mass or less, and particularly preferably 4% by mass or less.

The amount of adhesive adhered can be obtained from the following ignition loss values. The "ignition weight loss value" of the glass yarn referred to here can be measured according to the method described in JIS R3420. That is, first, the glass yarn is placed in a dryer at 110 ° C. and dried for 60 minutes. After drying, the glass yarn is transferred to a desiccator, left for 20 minutes, and allowed to cool to room temperature. After allowing to cool, weigh the glass thread in units of 0.1 mg or less. Next, the glass yarn is heated in a muffle furnace at 625 ° C. for 20 minutes. After heating in a muffle furnace, the glass yarn is transferred to a desiccator, left for 20 minutes, and allowed to cool to room temperature. After allowing to cool, weigh the glass thread in units of 0.1 mg or less. The amount of glue attached to the glass thread is the mass of the glue with respect to the mass of the glass thread to which the glue is attached (the difference between the mass of the glass thread measured after drying and the mass of the glass thread measured after heating in a muffle furnace). It is represented by the ratio of.
The glass cloth adhesive of the present invention does not substantially contain a silane coupling agent. After weaving the glass cloth, the adhesive is almost completely removed by heating, washing with water, etc. Therefore, if a silane coupling agent is contained, it may remain as a foreign substance on the glass surface.

The adhesive preferably contains, for example, one or more selected from the group consisting of starch, polyvinyl alcohol, polyethylene oxide, polyester, polyamide and the like.

Further, in the method for producing glass cloth of the present embodiment, when the surface of the glass thread is surface-treated with a silane coupling agent, the surface of the glass filament is almost completely treated with a treatment liquid having a concentration of 0.1 to 3.0% by mass. A coating step of covering the glass with a silane coupling agent, a fixing step of fixing the silane coupling agent to the surface of the glass filament by heating and drying, and a high-pressure spray water or the like for at least a part of the silane coupling agent fixed to the surface of the glass filament. Examples thereof include a method having a preparation step of adjusting the adhesion amount of the silane coupling agent so that the strong heat loss value becomes 0.2 to 1.0% by mass by washing with.

As the solvent for dissolving or dispersing the silane coupling agent, either water or an organic solvent can be used, but from the viewpoint of safety and protection of the global environment, it is preferable to use water as the main solvent. As a method of obtaining a treatment liquid using water as a main solvent, a method of directly adding a silane coupling agent to water, a method of dissolving the silane coupling agent in a water-soluble organic solvent to prepare an organic solvent solution, and then using the organic solvent solution. Any method of putting it in water is preferable. It is also possible to use a surfactant in combination in order to improve the water dispersibility and stability of the silane coupling agent in the treatment liquid.

The coating step, the fixing step, and the preparation step are preferably performed on the glass cloth after the weaving step. Further, if necessary, a fiber opening step of opening the glass yarn of the glass cloth may be provided after the weaving process. When the preparation step is performed after the weaving step, the preparation step may also serve as the fiber opening step. The composition of the glass cloth usually does not change before and after opening the fiber.

It is considered that the silane coupling agent layer can be formed almost completely and uniformly on the entire surface of each glass filament constituting the glass yarn by the above manufacturing method.

As a method of applying the treatment liquid to the glass cloth, (a) a method of collecting the treatment liquid in a bath and immersing and passing the glass cloth (hereinafter referred to as "immersion method"), (b) a roll coater, a die coater, and the like. Alternatively, a method of directly applying the treatment liquid to the glass cloth with a gravure coater or the like is possible. When applying by the dipping method of (a) above, it is preferable to select the immersion time of the glass cloth in the treatment liquid to be 0.5 seconds or more and 1 minute or less.

Further, as a method of applying the treatment liquid to the glass cloth and then heating and drying the solvent, known methods such as hot air and electromagnetic waves can be mentioned.

The heating and drying temperature is preferably 90 ° C. or higher, and more preferably 100 ° C. or higher so that the reaction between the silane coupling agent and the glass can be sufficiently performed. Further, in order to prevent deterioration of the organic functional group of the silane coupling agent, the temperature is preferably 300 ° C. or lower, more preferably 200 ° C. or lower.

The method for opening the fiber in the fiber opening step is not particularly limited, and examples thereof include a method for opening the glass cloth with spray water (high pressure water opening), vibro washer, ultrasonic water, mangle, and the like. .. In the fiber opening process, in the case of glass cloth having a SiO ₂ composition amount of 98 to 100% by mass, fluffing is likely to occur. On the other hand, when the ignition loss value of the glass cloth of the present embodiment is 0.2% by mass or more, fluffing can be suppressed. Further, in order to suppress the decrease in the tensile strength of the glass cloth due to the fiber opening process, it is preferable to take measures such as reducing the friction of the contact member when weaving the glass yarn, optimizing the sizing agent and increasing the adhesion amount. .. By lowering the tension applied to the glass cloth during the fiber opening process, the air permeability tends to be smaller.

It may have an arbitrary step even after the fiber opening step. The arbitrary process is not particularly limited, and examples thereof include a slitting process.

After the glass cloth is surface-treated, a matrix resin is applied to produce a prepreg. The storage period from the surface treatment of the glass cloth to the application of the matrix resin is preferably within 2 years. The storage temperature is preferably 10 to 40 ° C. When the storage temperature is 30 ° C. or lower, the deactivation of the unsaturated double bond group of the silane coupling agent on the surface of the glass cloth can be suppressed, and the reactivity with the matrix resin tends to be maintained. Further, when the storage period is within 2 years, it tends to be possible to suppress the reaction between the silane coupling agents due to the water adhering to the glass surface and the increase in the cohesiveness of the glass filament bundle. This tends to improve the permeability of the matrix resin.

[Prepreg]
The prepreg of the present embodiment has the above glass cloth and a matrix resin impregnated in the glass cloth. This makes it possible to provide a prepreg that is thin, has a low dielectric constant, and has improved insulation reliability by improving insulation reliability and moisture absorption resistance related to each of the above reasons.

As the matrix resin, either a thermosetting resin or a thermoplastic resin can be used. The thermosetting resin is not particularly limited, but for example, a) a compound having an epoxy group and an amino group, a phenol group, an acid anhydride group, a hydrazide group, an isocyanate group, a cyanate group, and a hydroxyl group that react with the epoxy group. An epoxy that is cured by reacting with a compound having at least one of the above, without a catalyst, or by adding a catalyst having a reaction catalytic ability such as an imidazole compound, a tertiary amine compound, a urea compound, and a phosphorus compound. Resin; b) A radical polymerization type curing resin in which a compound having at least one of an allyl group, a methacrylic group, and an acrylic group is cured by using a thermal decomposition type catalyst or a photodegradable type catalyst as a reaction initiator; c. ) Maleimide triazine resin in which a compound having a cyanate group and a compound having a maleimide group are reacted and cured; d) A thermosetting polyimide resin in which a maleimide compound and an amine compound are reacted and cured; e) Benzo Examples thereof include a benzoxazine resin in which a compound having an oxazine ring is cross-linked and cured by heat polymerization.

The thermoplastic resin is not particularly limited, but for example, polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyether sulfone, polyarylate, aromatic polyamide, polyether ether ketone, thermoplastic polyimide, insoluble polyimide, etc. Examples thereof include polyamide-imide and fluororesin. Further, the thermosetting resin and the thermoplastic resin may be used in combination.

[Printed wiring board]
The printed wiring board of this embodiment has the above-mentioned prepreg. This makes it possible to provide a printed wiring board having a low dielectric constant and improved insulation reliability.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

(Example 1)
An aqueous sizing agent containing 5% by mass of polyvinyl alcohol is applied by a dipping method, and a gluing step of adhering the sizing agent to the glass thread is performed. The amount of the sizing agent adhered in the sizing step is 2.2% by mass, SiO ₂ A weft made of a glass filament having a composition amount of 99.9% by mass (average filament diameter of glass filament 9 μm, number of filaments 100, driving density 54 / inch) was produced.

Similarly, a warp (of the glass filament) composed of a glass filament having a SiO ₂ composition amount of 53% by mass and a B ₂ O ₃ composition amount of 23% by mass, in which the amount of the glue adhered in the gluing step is 2.1% by mass. An average filament diameter of 6 μm, a number of filaments of 200, and a driving density of 61 / inch) were manufactured.

Using the warp and weft obtained as described above, a glass cloth (thickness 78 μm, cloth weight 70 g / m ² ) was woven. The woven glass cloth was subjected to a degluing step of removing the adhesive by heating at 400 ° C. The obtained glass cloth was added to a treatment solution in which N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was dispersed in water. Soaked and heated to dry. Next, high-pressure water defibration was carried out by spraying, and the product was obtained by heating and drying. The ignition loss value of the glass cloth was 0.32% by mass.

(Example 2)
An aqueous solution of a sizing agent containing 5% by mass of polyvinyl alcohol is applied by a dipping method, and a gluing step of adhering the sizing agent to the glass thread is performed. _The amount of the sizing agent adhered in the sizing step is 3.0% by mass. A weft made of a glass filament having a composition amount of 99.9% by mass (average filament diameter of glass filament 9 μm, number of filaments 100, driving density 54 / inch) was produced.

Similarly, a warp (of the glass filament) composed of a glass filament having a SiO ₂ composition amount of 53% by mass and a B ₂ O ₃ composition amount of 23% by mass, in which the amount of the glue adhered in the gluing step is 3.0% by mass. An average filament diameter of 6 μm, a number of filaments of 200, and a driving density of 61 / inch) were manufactured.

Using the warp and weft obtained as described above, a glass cloth (thickness 78 μm, cloth weight 70 g / m ² ) was woven. The woven glass cloth was subjected to a degluing step of removing the adhesive by heating at 400 ° C. The obtained glass cloth was added to a treatment solution in which N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was dispersed in water. Soaked and heated to dry. Next, high-pressure water defibration was carried out by spraying, and the product was obtained by heating and drying. The ignition loss value of the glass cloth was 0.32% by mass.

(Example 3)
An aqueous solution of a sizing agent containing ₅ % by mass of polyvinyl alcohol is applied by a dipping method to perform a gluing step of adhering the sizing agent to the glass thread, and the amount of the sizing agent adhered in the sizing step is 3.5% by mass. A weft made of a glass filament having a composition amount of 99.9% by mass (average filament diameter of glass filament 9 μm, number of filaments 100, driving density 54 / inch) was produced.

Similarly, a warp (of the glass filament) made of a glass filament having a SiO ₂ composition amount of 53% by mass and a B ₂ O ₃ composition amount of 23% by mass, in which the amount of the glue adhered in the gluing step is 3.5% by mass. An average filament diameter of 6 μm, a number of filaments of 200, and a driving density of 61 / inch) were manufactured.

Using the warp and weft obtained as described above, a glass cloth (thickness 78 μm, cloth weight 70 g / m ² ) was woven. The woven glass cloth was subjected to a degluing step of removing the adhesive by heating at 400 ° C. The obtained glass cloth was added to a treatment solution in which N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was dispersed in water. Soaked and heated to dry. Next, high-pressure water defibration was carried out by spraying, and the product was obtained by heating and drying. The ignition loss value of the glass cloth was 0.32% by mass.

(Example 4)
An aqueous solution of a sizing agent containing 5% by mass of polyvinyl alcohol is applied by a dipping method to perform a gluing step of adhering the sizing agent to the glass thread, and the amount of the sizing agent adhered in the sizing step is _2.6 % by mass. A weft made of a glass filament having a composition amount of 99.9% by mass (average filament diameter of glass filament 9 μm, number of filaments 100, driving density 54 / inch) was produced.

Similarly, a warp yarn made of a glass filament having a SiO ₂ composition amount of 99.9% by mass, in which the amount of the glue adhered in the gluing step is 2.6% by mass (average filament diameter of glass filament 9 μm, number of filaments 100). A book, a driving density of 54 pieces / inch) was manufactured.

Using the warp and weft obtained as described above, a glass cloth (thickness 78 μm, cloth weight 69 g / m ² ) was woven. The woven glass cloth was subjected to a degluing step of removing the adhesive by heating at 400 ° C. The obtained glass cloth was added to a treatment solution in which N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was dispersed in water. Soaked and heated to dry. Next, high-pressure water defibration was carried out by spraying, and the product was obtained by heating and drying. The ignition loss value of the glass cloth was 0.24% by mass.

(Example 5)
An aqueous solution of a sizing agent containing 5% by mass of polyvinyl alcohol is applied by a dipping method, and a gluing step of adhering the sizing agent to the glass thread is performed. _The amount of the sizing agent adhered in the sizing step is 3.7% by mass. A weft made of a glass filament having a composition amount of 99.9% by mass (average filament diameter of glass filament 9 μm, number of filaments 100, driving density 54 / inch) was produced.

Similarly, a warp yarn made of a glass filament having a SiO ₂ composition amount of 99.9% by mass (the average filament diameter of the glass filament is 9 μm, the number of filaments is 100), in which the amount of the glue adhered in the gluing step is 3.6% by mass. A book, a driving density of 54 pieces / inch) was manufactured.

Using the warp and weft obtained as described above, a glass cloth (thickness 78 μm, cloth weight 69 g / m ² ) was woven. The woven glass cloth was subjected to a degluing step of removing the adhesive by heating at 400 ° C. The obtained glass cloth was added to a treatment solution in which N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was dispersed in water. Soaked and heated to dry. Next, high-pressure water defibration was carried out by spraying, and the product was obtained by heating and drying. The ignition loss value of the glass cloth was 0.24% by mass.

(Comparative Example 1)
An aqueous sizing agent containing 5% by mass of polyvinyl alcohol is applied by a dipping method, and a gluing step of adhering the sizing agent to the glass thread is performed. The amount of the sizing agent adhered in the sizing step is 1.9% by mass, SiO ₂ A weft made of a glass filament having a composition amount of 99.9% by mass (average filament diameter of glass filament 9 μm, number of filaments 100, driving density 54 / inch) was produced.

Similarly, a warp (of the glass filament) composed of a glass filament having a SiO ₂ composition amount of 53% by mass and a B ₂ O ₃ composition amount of 23% by mass, in which the amount of the glue adhered in the gluing step is 1.9% by mass. An average filament diameter of 6 μm, a number of filaments of 200, and a driving density of 61 / inch) were manufactured.

Using the warp and weft obtained as described above, a glass cloth (thickness 78 μm, cloth weight 70 g / m ² ) was woven. The woven glass cloth was subjected to a degluing step of removing the adhesive by heating at 400 ° C. The obtained glass cloth was added to a treatment solution in which N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was dispersed in water. Soaked and heated to dry. Next, high-pressure water defibration was carried out by spraying, and the product was obtained by heating and drying. The ignition loss value of the glass cloth was 0.32% by mass.

(Comparative Example 2)
An aqueous sizing agent containing 5% by mass of polyvinyl alcohol is applied by a dipping method, and a gluing step of adhering the sizing agent to the glass thread is performed. The amount of the sizing agent adhered in the sizing step is 1.9% by mass, SiO ₂ A weft made of a glass filament having a composition amount of 99.9% by mass (average filament diameter of glass filament 9 μm, number of filaments 100, driving density 54 / inch) was produced.

Similarly, a warp (glass filament) made of a glass filament having a SiO ₂ composition amount of 53% by mass and a B ₂ O ₃ composition amount of 23% by mass, in which the amount of the glue adhered after the gluing step is 2.5% by mass. The average filament diameter of 6 μm, the number of filaments was 200, and the driving density was 61 / inch).

Using the warp and weft obtained as described above, a glass cloth (thickness 78 μm, cloth weight 70 g / m ² ) was woven. The woven glass cloth was subjected to a degluing step of removing the adhesive by heating at 400 ° C. The obtained glass cloth was added to a treatment solution in which N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was dispersed in water. Soaked and heated to dry. Next, high-pressure water defibration was carried out by spraying, and the product was obtained by heating and drying. The ignition loss value of the glass cloth was 0.32% by mass.

(Comparative Example 3)
An aqueous solution of a sizing agent containing 5% by mass of polyvinyl alcohol is applied by a dipping method, and a gluing step of adhering the sizing agent to the glass thread is performed. The amount of the sizing agent adhered in the sizing step is _2.5 % by mass. A weft made of a glass filament having a composition amount of 99.9% by mass (average filament diameter of glass filament 9 μm, number of filaments 100, driving density 54 / inch) was produced.

Similarly, a warp yarn made of a glass filament having a SiO ₂ composition amount of 99.9% by mass, in which the amount of the glue adhered in the gluing step is 1.5% by mass (average filament diameter of glass filament 9 μm, number of filaments 100). A book, a driving density of 54 pieces / inch) was manufactured.

Using the warp and weft obtained as described above, a glass cloth (thickness 78 μm, mass 69 g / m ² ) was woven. The woven glass cloth was subjected to a degluing step of removing the adhesive by heating at 400 ° C. The obtained glass cloth was added to a treatment solution in which N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was dispersed in water. Soaked and heated to dry. Next, high-pressure water defibration was carried out by spraying, and the product was obtained by heating and drying. The ignition loss value of the glass cloth was 0.24% by mass.

<Evaluation method of ignition loss value of glass cloth>
The ignition loss value was measured according to the method described in JIS R 3420. Specifically, the glass cloth was placed in a dryer at 105 ° C. ± 5 ° C. and dried for at least 30 minutes. After drying, the glass cloth was transferred to a desiccator and allowed to cool to room temperature. After allowing to cool, the weight of the glass cloth was measured in units of 0.1 mg or less. The glass cloth was then heated in a muffle furnace at about 625 ° C. for 20 minutes. After heating in a muffle furnace, the glass cloth was transferred to a desiccator and allowed to cool to room temperature. After allowing to cool, the weight of the glass cloth was measured in units of 0.1 mg or less. The weight change before and after heating of the muffle furnace was measured, and the ignition loss value was calculated as the amount of the treatment agent adhered.

<Evaluation method of adhesive amount>
The amount of adhesive adhered was measured according to the method described in JIS R3420. Specifically, the glass thread to which the adhesive was attached was placed in a dryer at 110 ° C. and dried for 60 minutes. After drying, the glass yarn was transferred to a desiccator, left for 20 minutes, and allowed to cool to room temperature. After allowing to cool, the glass yarn was measured in units of 0.1 mg or less. Next, the glass yarn was heated in a muffle furnace at 625 ° C. for 20 minutes. After heating in a muffle furnace, the glass yarn is transferred to a desiccator, left for 20 minutes, and allowed to cool to room temperature. After allowing to cool, the glass yarn was measured in units of 0.1 mg or less. From the ignition loss value obtained by the above measurement method, the amount of glue adhered to the glass thread (the mass of the glue relative to the mass of the glass thread to which the glue adhered (the mass of the glass thread measured after drying and heating in a muffle furnace). The ratio) of the difference from the mass of the glass thread measured later) was determined.

<Evaluation method of glass cloth thickness>
According to JIS R 3420 7.10, the spindle was gently rotated using a micrometer to bring it into light contact parallel to the measurement surface. I read the scale after the ratchet made three sounds.

<Evaluation of fluff of glass cloth (evaluation of bending resistance)>
The glass cloths obtained in the above-mentioned Examples and Comparative Examples were visually applied with a tension of 100 N / 1000 mm on a Roll-to-Roll inspection table and irradiated with a halogen lamp to 1 mm or more per 1 m ² . The number of protrusions was calculated.

<How to make a substrate>
A polyphenylene ether resin varnish (a mixture of 30 parts by mass of a modified polyphenylene ether resin, 10 parts by mass of triallyl isocyanurate, 60 parts by mass of toluene, and 0.1 part by mass of a catalyst) was added to the glass cloths obtained in the above Examples and Comparative Examples. It was impregnated and dried at 120 ° C. for 2 minutes to obtain a prepreg. This prepreg was layered, and copper foil having a thickness of 12 μm was layered on top and bottom, and heated and pressed at 200 ° C. and 40 kg / cm ² for 60 minutes to obtain a substrate.

<Evaluation method of dielectric constant of substrate and glass cloth>
As described above, a substrate was prepared so that the resin content per 100% by mass of the prepreg was 60% by mass, and the copper foil was removed to obtain a sample for dielectric constant evaluation. The dielectric constant of the obtained sample at a frequency of 1 GHz was measured using an impedance analyzer (manufactured by Agilent Technologies). From the obtained substrate dielectric constant, the dielectric constant of the glass cloth was calculated based on the volume fraction of the glass cloth and the resin dielectric constant of 2.5.

<Evaluation method of insulation reliability of substrate>
As described above, a substrate is prepared so as to have a thickness of 0.4 mm, and a wiring pattern in which through holes are arranged at intervals of 0.15 mm is prepared on copper foils on both sides of the substrate to prepare a sample for insulation reliability evaluation. Got A voltage of 10 V was applied to the obtained sample in an atmosphere of a temperature of 120 ° C. and a humidity of 85% RH, and the change in resistance value was measured. At this time, when the resistance became less than 1 MΩ within 500 hours after the start of the test, it was counted as an insulation defect. The same measurement was performed on 10 samples, and the ratio of the samples that did not have insulation failure in 10 samples was calculated.

<Evaluation method of interlayer insulation reliability of substrate>
As described above, a substrate is prepared so as to have a thickness of 0.1 mm, the copper foils on both sides of the substrate are partially etched with an aqueous iron chloride solution, and the copper foil portions of 10 mmΦ are left on both sides of the substrate. A sample for sex evaluation was obtained. A voltage of 10 V was applied to the obtained sample in an atmosphere of a temperature of 120 ° C. and a humidity of 85% RH, and the change in resistance value was measured. At this time, when the resistance became less than 1 MΩ within 500 hours after the start of the test, it was counted as an insulation defect. The same measurement was performed on 10 samples, and the ratio of the samples that did not have insulation failure in 10 samples was calculated.

The evaluation results of the glass cloth shown in Examples and Comparative Examples are summarized in Table 1.

It was found that the substrate obtained by using the glass cloth of the example had a low dielectric constant and was extremely excellent in insulation reliability.

The glass cloth of the present invention has industrial applicability as a base material used for a printed wiring board used in the electronic and electrical fields.

Claims (10)

A glass cloth made by weaving glass threads composed of a plurality of glass filaments as warps and wefts.
The average filament diameter of the warp and the glass filament constituting the weft is 3 μm to 10 μm.
The number of glass filaments of the warp and weft is 20 to 300, and the number of glass filaments is 20 to 300.
The driving densities of the warp and the weft are independently 20 to 140 threads / inch, respectively.
The thickness of the glass cloth is 8 μm to 100 μm.
The number of fluffs having a length of 1 mm or more observed when a tension of 100 N / 1000 mm is applied by Roll-to-Roll is 10 pieces / m ² or less.
The SiO ₂ composition amount of one of the warp and weft is 98% by mass or more and 100% by mass or less.
Glass cloth. The glass cloth according to claim 1, wherein the number of glass filaments arranged in the Z direction in the warp and the weft is 8 or less independently. The glass cloth according to claim 1 or 2, wherein the ignition loss value of the glass cloth is 0.2% by mass or more and 1.0% by mass or less. The glass cloth according to any one of claims 1 to 3, wherein the SiO ₂ composition amount of one of the warp and weft is 98% by mass or more and 99.99% by mass or less. The glass cloth according to any one of claims 1 to 4, wherein the glass cloth has a dielectric constant of 4.3 or less. The glass cloth according to any one of claims 1 to 5, wherein the surface of the glass thread is treated with a silane coupling agent. A gluing step of adhering a glue containing polyvinyl alcohol to glass yarn in an amount of 2% by mass or more and 10% by mass or less.
A weaving step of weaving a glass cloth using the glass yarn obtained by the gluing step as a warp and a weft,
A degluing step of removing the adhesive adhering to the glass cloth obtained by the weaving step and reducing the amount of the adhesive adhering to 0.1% by mass or less.
Including
The SiO ₂ composition amount of one of the warp and weft is 98% by mass or more and 100% by mass or less.
How to make glass cloth. The method for producing a glass cloth according to claim 7, wherein the gluing step is performed a plurality of times before the degluing step. The glass cloth according to any one of claims 1 to 6 and the glass cloth.
A matrix resin impregnated in the glass cloth, and the like.
Pre-preg. A printed wiring board having the prepreg according to claim 9 .