JP2018127748A - Glass cloth, prepreg, and printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass cloth having a low dielectric constant, a thin substrate, and an excellent interlayer insulation reliability, a prepreg using the glass cloth, and a printed wiring board. SOLUTION: The glass cloth is made by weaving a glass thread made of a plurality of glass filaments, and the SiO2 composition amount in the glass filament is 99.99 to 100% by mass, and the dielectric constant of the glass cloth. However, the thickness of the glass cloth is 3.8 or less, the thickness of the glass cloth is 11 μm or less, and the total number of warp and weft filaments constituting the glass cloth is 290,000 / m2 or more, 400,000 /. Glass cloth that is less than m2. [Selection diagram] None

Description

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

  Currently, along with the high performance and high speed communication of information terminals such as smartphones, the printed wiring boards used are becoming increasingly dense and extremely thin, and are also becoming increasingly low dielectric constant and low dielectric loss tangent. .

  As an insulating material of this printed wiring board, a laminated board obtained by laminating a prepreg obtained by impregnating a glass cloth with a thermosetting resin such as an epoxy resin (hereinafter referred to as “matrix resin”) and curing by heating and pressing. Is widely used. The dielectric constant of the matrix resin used for the high-speed communication substrate is about 3, whereas the dielectric constant of a general E glass cloth is about 6.7. It has become apparent. Note that the signal transmission loss is Edward A. As shown by the Wolff equation: transmission loss ∝√ε × tanδ, it is known that a 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 (for example, see Patent Documents 1 to 4).

Japanese Patent Laid-Open No. 5-170483 JP 2009-263569 A JP 2009-19150 A JP 2009-263824 A

However, in future 5G communication applications and the like, these low dielectric constant glass cloths still have room for improvement from the viewpoint of achieving sufficient transmission speed performance. Here, it is conceivable to further lower the dielectric constant and lower the dielectric loss tangent by setting the amount of SiO ₂ in the glass composition to approximately 100%. However, when the blending amount of SiO _{2 in} the glass composition is increased to almost 100%, the glass filament becomes brittle and easily broken, resulting in a quality defect such as fluff. When many large fluffs are generated, the probability that the conductor portion and the glass cloth come into contact with each other increases. As a result, there is a problem that insulation reliability between layers is deteriorated particularly in a thin laminated board.

  The present invention has been made in view of the above problems, and has a low dielectric constant, a thin substrate having excellent interlayer insulation reliability (“substrate” refers to a prepreg, a printed wiring board, or a laminate of these, etc. It is an object to provide a glass cloth, a prepreg using the glass cloth, and a printed wiring board.

  As a result of investigations to solve the above problems, the present inventors have found that a glass cloth having a predetermined range of the total number of glass filaments including warps and wefts constituting the glass cloth can solve the above problems. The invention has been completed.

That is, the present invention is as follows.
[1]
A glass cloth formed by weaving glass yarns composed of a plurality of glass filaments,
In the glass filament, the SiO ₂ composition amount is 99.99-100% by mass,
The dielectric constant of the glass cloth is 3.8 or less,
The glass cloth has a thickness of 11 μm or less,
The total number of filaments of the warp and weft constituting the glass cloth is 290,000 pieces / m ² or more and 400,000 pieces / m ² or less.
Glass cloth.
[2]
The glass cloth according to [1], wherein an average filament diameter of glass filaments constituting the glass cloth is 3.5 μm or more and 3.7 μm or less.
[3]
The glass cloth according to [1] or [2], wherein a driving density of the warp and the weft is independently 80 or more and 130 or less.
[4]
The glass cloth according to any one of [1] to [3], wherein the number of glass filaments constituting the glass yarn is 30 or more and 49 or less.
[5]
The glass cloth according to any one of [1] to [4], wherein an opening ratio of the glass cloth is 20% or less.
[6]
The glass cloth according to any one of [1] to [5], wherein an average area of openings of the glass cloth is 20,000 μm ² / piece or less.
[7]
The glass cloth according to any one of [1] to [6], wherein a cloth weight of the glass cloth is 5 g / m ² or more and 9 g / m ² or less.
[8]
The glass cloth according to any one of [1] to [7], wherein the warp and weft yarn counts (Tex) are each independently 0.2 g / 1000 m or more and 1.0 g / 1000 m or less.
[9]
The glass cloth according to any one of [1] to [8];
A matrix resin impregnated in the glass cloth,
Prepreg.
[10]
A printed wiring board having the prepreg according to [9].

  According to the present invention, it is possible to provide a glass cloth, a prepreg using the glass cloth, and a printed wiring board that can produce a substrate having a low dielectric constant, a thin film, and excellent interlayer insulation reliability.

  Hereinafter, the embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. However, the present invention is not limited to this, and various modifications are possible without departing from the scope of the present invention. It is.

〔Glass cloth〕
The glass cloth of the present embodiment is a glass cloth formed by weaving glass yarns composed of a plurality of glass filaments, wherein the glass filament has a SiO ₂ composition amount of 99.99 to 100% by mass, and the glass The cloth has a dielectric constant of 3.8 or less, the glass cloth has a thickness of 11 μm or less, and the total number of glass filaments of warps and wefts constituting the glass cloth is 290,000 pieces / m ² or more, 400, 000 pieces / m ² or less.

When the SiO ₂ composition amount is 99.99 to 100% by mass, the bending resistance of the glass filament is significantly lowered, and the glass filament is broken or broken. Broken or broken glass filaments contribute to the fluff of glass cloth. Since such fluffing can occur in the weaving process, washing process, and fiber opening process of glass cloth, a glass cloth with less fluffing is produced using a glass filament with a SiO ₂ composition of 99.99-100% by mass. It is not easy to do. The fluffing increases the probability that the fluffing portion collides with the conductive layer when producing a laminated plate, and causes a poor interlayer insulation. In particular, in the case of a thin glass cloth, the interlayer thickness is also thinned, so that the interlayer insulation failure due to fluff is more likely to occur. Therefore, a thin glass cloth using a glass filament having a SiO ₂ composition amount of 99.99 to 100% by mass has a problem from the viewpoint of practicality.

However, according to the glass cloth of the present embodiment, the total number of glass filaments of the warp and weft to be formed is 290,000 pieces / m ² or more and 400,000 pieces / m ² or less, so that the weaving process and the water washing process Also, the yarn breakage is less likely to occur with respect to the tension and processing pressure applied to the glass filament in the fiber opening process, and fluffing can be suppressed. In addition, by setting the total number of glass filaments of warp and weft to 400,000 pieces / m ² or less, the thickness of the glass cloth can be reduced and a thin substrate can be obtained. As a result, it is possible to provide a glass cloth that can produce a substrate that is thinner, has a lower dielectric constant, and has higher interlayer insulation reliability than conventional ones. Further, when the total number of glass filaments is larger than 400,000 / m ^2, it is necessary to increase the weave density. Therefore, the bending of the yarn becomes large at the intersection of the warp and the weft, and fuzzing is extremely likely to occur. In addition, the substrate using the glass cloth of the present embodiment has achieved further lower dielectric constant and lower dielectric loss tangent, and can achieve each performance required with higher speed communication. .
The total number of glass filaments of the warp and weft constituting the glass cloth is preferably 300,000 pieces / m ² or more and 380,000 pieces / m ² or less, more preferably 320,000 pieces / m ² or more, 360 1,000 pieces / m ² or less.
The total number of glass filaments can be controlled by adjusting the driving density and the number of glass filaments.

[Glass filament composition]
In the glass filament, the SiO ₂ composition amount is 99.99 to 100% by mass. Setting the SiO ₂ composition amount to 99.99 mass% or more can reduce the dielectric constant and dielectric loss tangent. Further, to the SiO ₂ composition weight and 99.99 wt% or more, to suppress the mixing of air during glass melt spinning, it is also possible to suppress the generation of the hollow fiber. As the number of hollow fibers increases, the insulation reliability of the substrate tends to deteriorate. On the other hand, by setting the SiO ₂ composition amount to 99.99% by mass or more, it is possible to provide a glass cloth that can produce a substrate having a low dielectric constant and excellent insulation reliability. . The SiO ₂ composition amount can be adjusted according to the amount of raw material used for glass filament preparation.

Further, the glass filament may have other composition besides SiO ₂ . Other compositions are not particularly limited, and examples 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. It is done.

[Average filament diameter of glass filament]
The average filament diameter of the glass filament constituting the glass yarn is preferably 2 to 6 μm, more preferably 3.5 μm to 3.7 μm, and further preferably 3.5 to 3.6 μm. By setting the average filament diameter of the glass filament to 2 μm or more, yarn breakage is less likely to occur against the tension and processing pressure applied to the glass filament in the weaving process, water washing process, and fiber opening process, and fuzz is suppressed. It becomes possible. Further, by setting the average filament diameter of the warp and weft to 6 μm or less, the thickness of the glass cloth can be reduced, and a thin substrate can be obtained. A glass cloth having a thickness of 11 μm or less can be realized while suppressing tension and processing pressure in a weaving process, a water washing process, and a fiber opening process and suppressing fuzz. In particular, by setting the average filament diameter of the glass filament to 3.5 μm to 3.6 μm, the variation in the thickness of the glass cloth can be suppressed. Can be prevented from being absorbed into the body, reducing the impact on health.

[Number of glass filaments]
The number of glass filaments of the glass filament constituting the glass yarn is preferably 30 to 100, and more preferably 30 to 49. When the number of glass filaments is within the above range, a glass cloth having a thickness of 11 μm or less can be realized while suppressing tension and processing pressure in the weaving process, washing process, and fiber opening process, and suppressing fuzz.

[Pumping density]
The driving density of the warp and the weft constituting the glass cloth is preferably independently from 50 to 140 yarns / inch, more preferably from 80 to 130 yarns / inch.

[Cloth weight (weight)]
The cloth weight (weight per unit area) of the glass cloth is preferably 4 to 10 g / m ² , more preferably 5 to 9 g / m ² , and further preferably 6 to 8 g / m ² .

[Weaving 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. Among these, a plain weave structure is preferable.

〔surface treatment〕
Glass yarn (including glass filaments) of 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. The use of a silane coupling agent having an unsaturated double bond group improves the reactivity with the matrix resin, and further improves the insulation reliability because a hydrophilic functional group hardly occurs after reacting with the matrix resin. .

Although it does not specifically limit as a silane coupling agent which has an unsaturated double bond group, For example, the compound shown by following General formula (1) is mentioned. By using such a silane coupling agent, moisture absorption resistance is further improved, and as a result, insulation reliability tends to be further improved. In particular, by using a silane coupling agent having an unsaturated double bond group, it is possible to infiltrate the plating solution after drilling a glass cloth having a SiO ₂ composition amount of 99.99 to 100% by mass, insulation reliability, In addition, the fluff 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 independently an alkoxy group, and n is 1 or more and 3 or less. And each R is independently a group 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 bond group, more preferably an organic functional group having three or more, and an amino group and an unsaturated double bond group More preferably, it is an organic functional group having at least four of the above. When X is such a functional group, moisture absorption resistance 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 alkoxy group, but an alkoxy group having 5 or less carbon atoms is preferable for stabilizing the glass cloth.

  Specific examples of silane coupling agents that can be used include, but are not limited to, 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 Trimethoxysilane, methacryloxyoctyltrimethoxysilane, acryloxypropyl Known substances, such as trimethoxysilane and the like. The silane coupling agent tends to be excellent in reactivity with a glass cloth glass fiber (glass filament) and a matrix resin of a substrate, particularly a radical polymerization resin. Therefore, it is possible to suppress a decrease in insulation reliability resulting from the resin and the glass cloth being easily peeled at the interface, and to suppress a decrease in insulation reliability resulting from the plating solution soaking into the glass cloth. In addition, the processing amount by the surface treating agent of glass cloth can be estimated by the following ignition loss value.

[Ignition loss value]
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 the ignition loss value of the glass cloth is preferably 0.40% by mass. Or less, more preferably 0.35% by mass or less. When the loss weight loss value of the glass cloth is 0.2% by mass or more, the plating solution infiltration property after the drilling of the glass cloth having the SiO ₂ composition amount of 99.99 to 100% by mass, the insulation reliability, In addition, the fluff quality can be improved. Furthermore, when the ignition loss value of the glass cloth is 0.2% by mass or more, the moisture absorption resistance is further improved, and the decrease in insulation reliability due to moisture absorption can be further suppressed. Moreover, when the ignition loss value of the glass cloth is 0.4% 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 loss value” mentioned 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, the glass cloth is transferred to a desiccator, left for 20 minutes, and allowed to cool to room temperature. After standing to cool, the glass cloth is weighed 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 the muffle furnace, the glass cloth is transferred to a desiccator, left for 20 minutes, and allowed to cool to room temperature. After standing to cool, the glass cloth is weighed in units of 0.1 mg or less. The amount of silane coupling agent treated with glass cloth 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 3.8 or less, preferably 3.7 or less. The dielectric constant of the glass cloth can be measured by the method described in the examples.

[Opening ratio of glass cloth]
The opening ratio of the glass cloth represents the area ratio of the portion in which neither the warp nor the weft is distributed with respect to the entire area of the glass cloth, and is preferably 20% or less from the viewpoint of suppressing unevenness of resin coating during prepreg coating. Preferably it is 18% or less.
The opening ratio of the glass cloth can be adjusted by the driving density, the fiber opening degree, and the glass yarn count.
Specifically, the aperture ratio can be measured by the method described in Examples.

[Average area of glass cloth openings]
The average area of the opening of the glass cloth represents the average value of the area of the part alone where neither the warp nor the weft is distributed, and is preferably 20,000 μm ² / piece or less from the viewpoint of suppressing unevenness of resin coating during prepreg coating. More preferably, it is 15,000 μm ² / piece or less.
The average area of the opening of the glass cloth can be adjusted by the driving density, the degree of opening, and the count of the glass yarn.
Specifically, the average area of the opening of the glass cloth can be measured by the method described in Examples.

[Counter]
From the viewpoint of thinning the glass cloth, the warp and weft yarn count (hereinafter also referred to as Tex) constituting the glass cloth are each independently 0.2 g / 1000 m or more and 1.0 g / 1000 m or less. Preferably, it is 0.5 g / 1000 m or more and 1.0 g / 1000 m or less.
The Tex of the glass cloth can be specifically calculated by the method described in the examples.

[Glass cloth manufacturing method]
The method for producing the glass cloth of the present embodiment is not particularly limited. For example, a coating step of almost completely covering the surface of the glass filament with a silane coupling agent with a treatment liquid having a concentration of 0.1 to 3.0 wt%, and heating And a fixing step of fixing the silane coupling agent to the surface of the glass filament by drying.
Moreover, the manufacturing method of the glass cloth of this embodiment wash | cleans at least one part of the silane coupling agent fixed to the surface of the glass filament with high pressure spray water etc., and an ignition loss value is 0.12-0. A preparation step of adjusting the adhesion amount of the silane coupling agent so as to be 40% by mass may be included.

  As the solvent for dissolving or dispersing the silane coupling agent, either water or an organic solvent can be used, but water is preferably used as the main solvent from the viewpoint of safety and protection of the global environment. As a method for obtaining a treatment liquid containing water as a main solvent, a method in which a silane coupling agent is directly added to water, an organic solvent solution is prepared by dissolving the silane coupling agent in a water-soluble organic solvent, and then the organic solvent solution is used. Any one of the methods of adding to water is preferable. In order to improve the water dispersibility and stability of the silane coupling agent in the treatment liquid, a surfactant may be used in combination.

  The covering step, the fixing step, and the preparation step are preferably performed on the glass cloth after the weaving step. Furthermore, you may have the fiber opening process which opens the glass yarn of a glass cloth after a weaving process as needed. In addition, when performing a preparation process after a weaving process, an adjustment process may serve as a fiber opening process. In addition, the composition of the glass cloth does not usually change before and after opening.

  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 production method.

  As a method of applying the treatment liquid to the glass cloth, (a) a method of storing 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, Or the method of apply | coating a process liquid directly to glass cloth with a gravure coater etc. is possible. When applying by the immersion method (a), the immersion time of the glass cloth in the treatment liquid is preferably selected to be 0.5 seconds or more and 1 minute or less.

  In addition, examples of the method for heating and drying the solvent after applying the treatment liquid to the glass cloth include known methods such as hot air and electromagnetic waves.

  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 glass is sufficiently performed. Moreover, in order to prevent deterioration of the organic functional group which a silane coupling agent has, heat drying temperature becomes like this. Preferably it is 300 degrees C or less, More preferably, it is 200 degrees C or less.

In addition, the opening method in the opening step is not particularly limited, and examples thereof include a method of opening a glass cloth with spray water (high-pressure water opening), vibrowasher, ultrasonic water, mangle and the like. . In the fiber opening process, in the case of a glass cloth having a SiO ₂ composition amount of 99.99 to 100% by mass, fuzz is likely to occur. On the other hand, the ignition loss value of the glass cloth of the present embodiment is 0.12% by mass or more, whereby fuzz can be suppressed. In order to suppress a decrease in the tensile strength of the glass cloth due to the opening process, it is preferable to take measures such as reducing friction of the contact member when weaving the glass yarn, optimizing the sizing agent and increasing the amount of adhesion. There is a tendency that the air permeability can be further reduced by lowering the tension applied to the glass cloth during the opening process.

  Even after the opening process, an optional process may be included. Although it does not specifically limit as an arbitrary process, For example, a slit process process is mentioned.

  After the glass cloth is surface-treated, a matrix resin is applied to manufacture a prepreg. The storage period between the surface treatment of the glass cloth and the application of the matrix resin is preferably within 2 years. Moreover, it is preferable that storage temperature shall be 10-40 degreeC. When the storage temperature is 30 ° C. or lower, the deactivation of unsaturated double bond groups 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. Moreover, it exists in the tendency which can suppress that the silane coupling agent reacts with the water adhering to the glass surface, and the convergence property of a glass filament bundle increases because storage period is less than two years. This tends to improve the permeability of the matrix resin.

[Prepreg]
The prepreg of this embodiment has the glass cloth and a matrix resin impregnated in the glass cloth. Accordingly, it is possible to provide a prepreg that is thin, has a low dielectric constant, and has improved insulation reliability and improved moisture absorption resistance related to 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. 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, or a phosphorus compound. A resin; b) a radical polymerization curable resin in which a compound having at least one of an allyl group, a methacryl group, and an acryl group is cured using a thermal decomposition catalyst or a photodecomposition catalyst as a reaction initiator; c D) a maleimide triazine resin cured by reacting a compound having a cyanate group with a compound having a maleimide group; Imide compounds, thermosetting polyimide resin is cured by reacting an amine compound, a; benzoxazine resin to crosslink cured by thermal polymerization of a compound having e) benzoxazine ring are exemplified.

  The thermoplastic resin is not particularly limited. For example, polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyether sulfone, polyarylate, aromatic polyamide, polyether ether ketone, thermoplastic polyimide, insoluble polyimide, Examples include polyamide imide and fluororesin. Moreover, you may use together a thermosetting resin and a thermoplastic resin.

[Printed wiring board]
The printed wiring board of this embodiment has the prepreg. Thereby, a printed wiring board having a low dielectric constant and improved insulation reliability can be provided.
The prepreg in the printed wiring board of the present embodiment may be a laminate composed of two or more layers.

  Next, the present invention will be described in more detail with reference to examples and comparative examples. The present invention is not limited in any way by the following examples.

Example 1
Glass cloth made by weaving glass yarn composed of glass filaments of SiO ₂ of 100% by mass (average filament diameter of glass filament 3.6 μm, number of glass filaments 40, warp driving density 120 / inch, weft driving density 120 pieces / inch, a total number of glass filaments of 380,000 pieces / m ² , a thickness of 11 μm, a fabric weight of 8 g / m ² , TEX 0.9 g / 1000 m) was added to N-β- (N-vinylbenzylaminoethyl) -γ-. Aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was immersed in a treatment solution dispersed in water and dried by heating. Next, high-pressure water opening was carried out by spraying and heat drying to obtain a product. The loss on ignition value of the glass cloth was 0.21 wt%. The opening ratio of the glass cloth was 10%. The average area of the openings of the glass cloth was 5,000 μm ² / piece.

(Example 2)
Glass cloth made by weaving glass yarns composed of glass filaments with SiO ₂ of 100% by mass (average filament diameter of glass filaments 3.6 μm, number of glass filaments 40, warp driving density 95 / inch, weft driving density 95 pieces / inch, a total number of glass filaments of 300,000 pieces / m ² , a thickness of 10 μm, a fabric weight of 7 g / m ² , TEX 0.9 g / 1000 m) are added to N-β- (N-vinylbenzylaminoethyl) -γ-. Aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was immersed in a treatment solution dispersed in water and dried by heating. Next, high-pressure water opening was carried out by spraying and heat drying to obtain a product. The loss on ignition value of the glass cloth was 0.21 wt%. The opening ratio of the glass cloth was 20%. The average area of the openings of the glass cloth was 15,000 μm ² / piece.

(Comparative Example 1)
Glass cloth made by weaving glass yarn composed of glass filaments of SiO ₂ of 100% by mass (average filament diameter of glass filament 3.6 μm, number of glass filaments 40, warp driving density 140 / inch, weft driving density 140 pieces / inch, total number of glass filaments 440,000 pieces / m ² , thickness 12 μm, fabric weight 10 g / m ² , TEX 0.9 g / 1000 m) were added to N-β- (N-vinylbenzylaminoethyl) -γ-. Aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was immersed in a treatment solution dispersed in water and dried by heating. Next, high-pressure water opening was carried out by spraying and heat drying to obtain a product. The loss on ignition value of the glass cloth was 0.21 wt%. The aperture ratio of the glass cloth was 5%. The average area of the openings of the glass cloth was 2000 μm ² / piece.

(Comparative Example 2)
Glass cloth made by weaving glass yarn composed of glass filaments of SiO ₂ of 100% by mass (average filament diameter of glass filament 3.6 μm, number of glass filaments 40, warp driving density 70 / inch, weft driving density 70 / inch, total number of glass filaments 220,000 / m ² , thickness 10 μm, fabric weight 5 g / m ² , TEX 0.9 g / 1000 m) is N-β- (N-vinylbenzylaminoethyl) -γ- Aminopropyltrimethoxysilane hydrochloride (manufactured by Toray Dow Corning Co., Ltd .; Z6032) was immersed in a treatment solution dispersed in water and dried by heating. Next, high-pressure water opening was carried out by spraying and heat drying to obtain a product. The loss on ignition value of the glass cloth was 0.21 wt%. The opening ratio of the glass cloth was 40%. The average area of the openings of the glass cloth was 50,000 μm ² / piece.

<Measurement method of count (TEX)>
The count was calculated by the following formula.
t = m / l × 1000
t: Count (tex)
m: Mass of the test piece (g)
l: Length of test piece (m)

<Opening ratio of glass cloth>
The aperture ratio of the glass cloth is measured with an optical microscope at a magnification of 100 times, the surface of the glass cloth is observed, the width of the warp and the width of the weft are arbitrarily measured at 100 locations, and the average value of the warp width (Wt), And the average value (Wy) of the weft width was calculated and calculated by the following formula.
O = (25.4 / Dt * 1000-Wt) * (25.4 / Dy * 1000-Wy) / (25.4 / Dt * 1000) * (25.4 / Dy * 1000)
O: Opening ratio (%)
Dt: Warp threading density (2 / 25.4mm)
Dy: Weft driving density (book / 25.4mm)
Wt: Average warp width (μm)
Wy: Average weft width (μm)

<Average area of glass cloth openings>
The average area of the opening of the glass cloth was measured with an optical microscope at a magnification of 100 times, the surface of the glass cloth was observed, and the width of the warp and the width of the weft were measured arbitrarily at 100 locations. Wt) and the average value (Wy) of the weft width were obtained and calculated by the following formula.
Oa = (25.4 / Dt * 1000-Wt) * (25.4 / Dy * 1000-Wy)
Oa: average area of opening of glass cloth (μm ² )
Dt: Warp threading density (2 / 25.4mm)
Dy: Weft driving density (book / 25.4mm)
Wt: Average warp width (μm)
Wy: Average weft width (μm)

<Evaluation method of ignition loss value of glass cloth>
The ignition loss value was measured according to the method described in JIS R3420. 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 standing to cool, the weight of the glass cloth was measured in units of 0.1 mg or less. Next, the glass cloth was heated in a muffle furnace at about 625 ° C. for 20 minutes. After heating in the muffle furnace, the glass cloth was transferred to a desiccator and allowed to cool to room temperature. After standing to cool, the weight of the glass cloth was measured in units of 0.1 mg or less. The change in weight before and after heating of the muffle furnace was measured, and the ignition loss value was calculated as the amount of treatment agent attached.

<Evaluation method of glass cloth thickness>
In accordance with JIS R 3420 7.10, using a micrometer, the spindle is gently rotated to lightly touch the measurement surface in parallel. Read the scale after the ratchet makes three sounds.

<Evaluation of fluff of glass cloth (flexibility evaluation)>
Polyphenylene ether resin varnish (mixture of modified polyphenylene ether resin 30 parts by weight, triallyl isocyanurate 10 parts by weight, toluene 60 parts by weight, catalyst 0.1 part by weight) is added to the glass cloth obtained in the above-mentioned examples and comparative examples. A prepreg was obtained after impregnation and drying at 120 ° C. for 2 minutes. The resin content of this prepreg was adjusted to 50% by mass. Next, a small sample of 100 mm × 100 mm at an arbitrary location was cut out, and the number of protrusions was determined visually.

<Manufacturing method of substrate>
Polyphenylene ether resin varnish (mixture of modified polyphenylene ether resin 30 parts by weight, triallyl isocyanurate 10 parts by weight, toluene 60 parts by weight, catalyst 0.1 part by weight) is added to the glass cloth obtained in the above-mentioned examples and comparative examples. A prepreg was obtained after impregnation and drying at 120 ° C. for 2 minutes. This prepreg was stacked, a copper foil having a thickness of 12 μm was stacked on the 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>
A substrate was prepared as described above 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.

<Method for evaluating interlayer insulation reliability of substrate>
As described above, the substrate is prepared to have a thickness of 0.04 mm, the copper foils on both sides of the substrate are partially etched with an aqueous iron chloride solution, and a 10 mmφ copper foil part is left on both sides of the substrate, thereby providing interlayer insulation reliability. 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 a change in resistance value was measured. At this time, the case where the resistance was less than 1 MΩ within 500 hours after the start of the test was counted as an insulation failure. The same measurement was performed on 10 samples, and the ratio of the samples that did not show an insulation failure among the 10 samples was calculated.

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

  The glass cloth of the example was found to have a low dielectric constant and very good interlayer 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 / electric field.

Claims (10)

A glass cloth formed by weaving glass yarns composed of a plurality of glass filaments,
In the glass filament, the SiO ₂ composition amount is 99.99-100% by mass,
The dielectric constant of the glass cloth is 3.8 or less,
The glass cloth has a thickness of 11 μm or less,
The total number of filaments of the warp and weft constituting the glass cloth is 290,000 pieces / m ² or more and 400,000 pieces / m ² or less.
Glass cloth.   The glass cloth of Claim 1 whose average filament diameter of the glass filament which comprises the said glass cloth is 3.5 micrometers or more and 3.7 micrometers or less.   The glass cloth according to claim 1 or 2, wherein the driving density of the warp and the weft is independently 80 / inch or more and 130 / inch or less.   The glass cloth according to any one of claims 1 to 3, wherein the number of glass filaments constituting the glass yarn is 30 or more and 49 or less.   The glass cloth according to any one of claims 1 to 4, wherein an opening ratio of the glass cloth is 20% or less. The glass cloth according to any one of claims 1 to 5, wherein an average area of openings of the glass cloth is 20,000 µm ² / piece or less. The glass cloth according to any one of claims 1 to 6, wherein a cloth weight of the glass cloth is 5 g / m ² or more and 9 g / m ² or less.   The glass cloth according to any one of claims 1 to 7, wherein a count (Tex) of the warp and the weft is independently 0.2 g / 1000 m or more and 1.0 g / 1000 m or less. The glass cloth according to any one of claims 1 to 8,
A matrix resin impregnated in the glass cloth,
Prepreg.   A printed wiring board having the prepreg according to claim 9.