CN116732678A - glass cloth - Google Patents

Abstract

Provided is a glass cloth which has a low dielectric loss tangent at 10-40 GHz, a low transmission loss, and easy workability. A glass cloth which is formed by adhering a silane coupling agent in an amount of 0.001 mass% or more and less than 1.0 mass% relative to the glass cloth, the silane coupling agent being formed by glass fibers having a softening point of 1000-1600 ℃ and an Si-OH group content of less than 1000 ppm.

Description

glass cloth

Technical field

The present invention relates to glass cloth excellent in dielectric properties and workability.

Background technique

Nowadays, as smart phones and other information terminals become more advanced in performance and high-speed communication, the printed wiring boards used are becoming more dense and extremely thin, and the dielectric constant, especially the dielectric loss angle, is becoming lower. Tangentization develops significantly.

As an insulating material for printed wiring boards, a laminate in which a prepreg obtained by impregnating glass cloth with a thermosetting resin such as epoxy resin (hereinafter referred to as "matrix resin") is laminated and cured under heat and pressure is widely used. plate. The dielectric constant of the above-mentioned base resin used in high-speed communication substrates is about 3. In contrast, the dielectric constant of general E-glass cloth is about 6.7. The problem of high dielectric constant when laminating boards is more obvious.

It should be noted that the signal transmission loss is shown by the Edward A. Wolff formula: transmission loss ∝√ε×tanδ. It is known that materials with smaller dielectric constant (ε) and dielectric loss tangent (tanδ) can be improved, especially , it can be seen from the above formula that the dielectric loss tangent (tanδ) contributes greatly to the transmission loss.

Therefore, glass cloths with improved dielectric properties such as D glass, NE glass, and L glass, which are different in glass composition from E glass, have been proposed (Patent Documents 1 to 3).

However, from the perspective of achieving sufficient transmission speed performance in future 5G communications applications, even these low dielectric properties glass cloths with excellent low dielectric constant and low dielectric loss tangent can be improved. necessity. Therefore, studies have been conducted to achieve further low dielectric constant and low dielectric loss tangent by setting the blending amount _{of SiO 2 in} the glass composition to approximately 100 mass %. Development of glass cloth (Patent Document 4). However, Patent Document 4 mentions low dielectric constant, but does not mention the dielectric loss tangent that contributes more to transmission loss, making low dielectric loss tangent a difficult problem to solve.

In terms of transmission loss, it is known that if Si-OH groups are present, the absorption of the harmonics of the vibration of Si-OH is located at 1.4 μm, so the transmission efficiency is significantly reduced. The reduction of Si-OH groups is effective in reducing transmission loss. Technology.

As a method of reducing the dielectric loss tangent, a method using synthetic quartz glass has been developed (Patent Document 5). However, Patent Document 5 describes the dielectric loss tangent up to 10 GHz, but does not describe the dielectric loss tangent in the millimeter wave region of 30 GHz to 300 GHz that has been sought in recent years. In addition, the price of synthetic quartz glass is high, which poses a cost problem when used for 5G communications, which is expected to be widespread in the future.

In addition, Patent Document 5 describes the ease of processability when forming a multilayer substrate as an advantage of using synthetic quartz glass, but points out the disadvantage of poor processability of natural quartz glass materials.

existing technical documents

patent documents

Patent Document 1: Japanese Patent Application Publication No. 5-170483

Patent Document 2: Japanese Patent Application Publication No. 2009-263569

Patent Document 3: Japanese Patent Application Publication No. 2009-19150

Patent Document 4: Japanese Patent Application Publication No. 2018-197411

Patent Document 5: Japanese Patent No. 4336086

Contents of the invention

Invent the problem to be solved

The present invention was completed in view of the above problems, and aims to provide a glass cloth that has a low dielectric loss tangent at 10 to 40 GHz, a small transmission loss, and is easy to process.

Means used to solve problems

The inventors of the present invention conducted intensive research in order to achieve the above object and found out that a specific amount of a silane coupling agent is attached to a glass cloth using glass fibers with a softening point of 1000 to 1600° C. and an amount of Si-OH groups of less than 1000 ppm. Glass cloth can solve the above-mentioned problems, and the present invention was completed. More specifically, as a method for suppressing the number of high-speed communications such as 5G that will increase in the future.

The transmission loss method seeks to further improve the dielectric loss tangent characteristics of the glass cloth used for the substrate. For example, the dielectric loss tangent from 10 GHz to 40 GHz is 0.002 or less, and the 40 GHz/10 GHz ratio is 2.0 or less. It is possible to suppress the transmission loss caused by the dielectric loss tangent characteristic, which is a significantly large effect.

Therefore, the present invention provides glass cloth.

1. Glass cloth, which is a glass cloth (or a glass cloth containing the glass fiber) composed of glass fibers with a softening point of 1000 to 1600° C. and a Si-OH group content of less than 1000 ppm. The ratio of the glass cloth to the glass cloth is 0.001 It is composed of silane coupling agent in an amount of not less than 1.0% by mass but less than 1.0% by mass.

2. The glass cloth according to 1, wherein the dielectric loss tangent from 10 GHz to 40 GHz is 0.002 or less, and the dielectric loss tangent ratio at 40 GHz/10 GHz is 2.0 or less.

3. The glass cloth according to 1 or 2, wherein the SiO ₂ amount in the glass fiber is 99.9 mass% or more.

4. The glass cloth according to any one of 1 to 3, having a thickness of 200 μm or less.

5. The glass cloth according to any one of 1 to 4, wherein the mass per unit area is 4 to 300 g/m ² .

Effect of the invention

According to the present invention, a glass cloth excellent in dielectric loss tangent characteristics and workability can be obtained.

Detailed ways

The present invention will be described in detail below, and these embodiments will be shown as exceptions. It goes without saying that various modifications can be made without departing from the technical idea of the present invention. The glass cloth of the present invention is a glass cloth composed of glass fibers with a softening point of 1000 to 1600° C. and a Si-OH group content of less than 1000 ppm. A silane coupling agent is adhered to the glass cloth at an adhesion rate of 0.001 mass % or more and less than 1.0 mass %. The resulting glass cloth (hereinafter, sometimes referred to as the attached glass cloth of the present invention).

[glass fiber]

The glass fiber of the present invention has a softening point of 1000 to 1600°C and a Si-OH group content of less than 1000 ppm.

Even if the composition of glass is the same, the structure and physical properties of the glass are different due to the heat treatment and the cooling rate during the treatment. It is affected by the cooling process of the glass from the completely molten state, and if the cooling rate is different, the hypothetical temperature is different. If the cooling rate is slow, there will be enough time for the structure to relax, and the virtual temperature will follow the actual temperature and decrease. On the other hand, when the cooling rate is high, the virtual temperature rises because it is far away from the actual temperature of the glass. In addition, as a change caused by a virtual temperature increase, the softening point decreases. The softening point of the glass fiber of the present invention is 1000-1600°C, preferably 1000-1400°C, more preferably 1050-1200°C. In addition, the softening point is a value measured by stretching the glass fiber in the radial direction (diameter direction) using a thermomechanical analyzer (TMA).

The Si-OH group content of the glass fiber of the present invention is less than 1000 ppm (mass). In addition, the method for measuring the Si-OH group content is the method described in the Examples. A correlation was found between the viscosity (Pa·s) of glass and the OH content, and it is known that as the OH content increases, the viscosity decreases. As the viscosity decreases, the softening point also decreases. Although the OH content can increase the heat treatment stretching in the hydrogen-oxygen flame, if it is excessively increased, the dielectric loss tangent becomes worse. The softening point and the amount of Si-OH groups can be adjusted using the glass fiber manufacturing method.

The SiO ₂ content of the glass fiber is preferably 99.9% by mass or more, and may be 100% by mass. Examples of methods for producing quartz glass raw material ingots include the electric melting method using crystal as a raw material, the flame fusion method, the direct synthesis method using silicon tetroxide as the raw material, the plasma synthesis method, the soot method, or using silicate alkane. The production method is not limited to the sol-gel method using base ester as a raw material, as long as the SiO ₂ compounding amount is 99.9 mass%. In particular, the electrofusion method using crystal as a raw material, the plasma synthesis method using silicon tetroxide as a raw material, and the soot method are preferable because they are less likely to contain silanol groups (Si-OH) as impurities.

The fiber diameter φ of the glass fiber is preferably 3 to 10 μm, more preferably 3.5 to 10 μm. The dielectric loss tangent of the glass fiber from 10 GHz to 40 GHz is preferably 0.002 or less, and more preferably 0.0015 or less. In addition, the change amount of the dielectric loss tangent is required to be small, and the ratio of 40GHz/10GHz is preferably 2.0 or less.

In order to balance the properties of processability and dielectric loss tangent, the glass material is stretched at a speed of 300 m/min or more, more preferably 400 m/min or more, which is 10 times or more, more preferably 20 times or more, larger than the target fiber diameter. , a glass fiber with low dielectric loss tangent and easy processability can be obtained.

As a method of preparing the stretched glass material, for example, as a method of preparing quartz glass filaments with a diameter of 200±100 μm and a _SiO2 content of 99.0% by mass or more, electric melting is used. Specifically, glass with a diameter of 50 to 200 mm is melted at 1700 to 2300° C., and the filament-shaped product is wound, thereby obtaining a glass fiber with a diameter of 200±100 μm. If the melting temperature is less than 1700°C, the quartz glass may not be melted. If the melting temperature exceeds 2300°C, the viscosity may be excessively reduced and stable stretching may not be possible.

Since the strength of glass yarn is very weak, it is preferably coated in order to obtain the strength required for winding. As the coating agent, a UV curable resin having an acrylic functional group that is excellent in curability is preferred, and the coating thickness is preferably 5 μm or more. If it is less than 5 μm, the coating thickness is insufficient and the reinforcing effect may not be obtained.

In order to improve productivity, it is preferable to cool the quartz glass from melting to coating. Cooling includes water cooling, air cooling, etc., both of which are effective. By heating quartz glass with a diameter of 50 to 200 mm to 1700 to 2300°C and cooling it, the softening point can be lowered even in this step.

[Glass strand]

The above-mentioned glass fibers are bundled to obtain glass strands. For example, the tow can be obtained by melting 20 to 400 quartz glass fibers using a mixed flame of oxygen and hydrogen. During the production of glass strands, a sizing agent is used to assemble the glass strands. As the sizing agent, a composition containing starch as the main raw material is used, and in order to impart functionality, a softener and a lubricant can be blended.

[Glass yarn(ガラスヤーン)]

By twisting the above-mentioned glass strands, a glass yarn can be obtained. The frequency of twisting is preferably 0.1 to 5.0 times per 25 mm, and more preferably 0.1 to 4.0 times.

[Glass cloth (before attachment)]

Glass cloth can be obtained by weaving the above glass yarn. The fabric structure, fabric density, etc. of the glass cloth are not particularly limited. Examples of the fabric structure include plain weave fabric, satin weave fabric, square weave fabric, twill weave fabric, and the like. In addition, the fabric density may be, for example, 10 to 150 threads/25 mm.

The thickness of the glass cloth is preferably 200 μm or less, more preferably 180 μm or less. The mass per unit area of the glass cloth is preferably 4 to 300 g/m ² , more preferably 10 to 200 g/m ² .

The weaving method of the glass cloth is not particularly limited, and examples thereof include air-jet looms, water-jet looms, rapier looms, and shuttle looms.

When weaving glass cloth, a paste can be used for the purpose of stabilizing weaving and suppressing fluffing. The paste preferably contains one or more types selected from the group consisting of polyvinyl alcohol, polyethylene oxide, starch, polyester, polyamide, and the like. Glass cloth can be fiber-opened as needed.

As the glass cloth, for example, quartz glass cloth (1078: IPC-4412B Appendix II) composed of filaments containing 99.9% by mass or more of SiO ₂ or the like can be used.

[Glass cloth (after attachment)]

The adhered glass cloth of the present invention is a glass cloth to which a silane coupling agent is adhered at an adhesion rate of 0.001 mass % or more and less than 1.0 mass %. The above-mentioned glass strands, glass yarns, and glass cloths can be surface treated with a silane coupling agent. obtained by processing.

The attached glass cloth of the present invention is treated with a silane compound and a silane coupling agent (processing agent) in order to develop the impregnation of the resin and the adhesiveness of the interface between the resin and the glass cloth. The silane coupling agent can be selected according to the glass cloth used, and one type can be used alone or two or more types can be used in combination. As the silane coupling agent, for example, a silane coupling agent having a functional group such as a vinyl group, a styrene group, a methacryloyl group, and an acryl group is preferred. Specific examples of the silane coupling agent include γ-methacryloyloxypropyldimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyltrimethoxysilane. Oxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, p-styryltrimethoxysilane, etc. . Examples of conventionally used silane coupling agents for epoxy resins include epoxy silane coupling agents and cationic silane coupling agents. In addition, a phenylaminosilane treatment agent that is excellent in solder heat resistance, moisture absorption resistance, copper strip heat resistance, and insulation reliability can also be used. Among them, unsaturated group-containing functional groups that are stable on the treated surface and have functional groups that can be chemically bonded to organic resins are preferred. For example, vinyl-based, (meth)acrylic-based, and styrene-based silane coupling agents are preferred. . As the silane coupling agent, for example, a silane coupling agent having a methacryloyl group (KBM-503: methacryloyloxypropyltrimethoxysilane manufactured by Shin-Etsu Chemical Industry Co., Ltd.) can be used.

Regarding the silane coupling treatment method, as long as the silane coupling agent comes into contact with the glass cloth to achieve a specific adhesion amount, the temperature and the like are not particularly limited. The adhesion amount of the treatment agent is 0.001 mass % or more and less than 1.0 mass % (adhesion rate) relative to the glass cloth, and preferably 0.01 mass % or more and 0.3 mass % or less. If the adhesion amount is 1.0% by mass or more, the dielectric loss tangent will be deteriorated. If the adhesion amount is less than 0.001% by mass, the wettability with resin will be deteriorated.

The dielectric loss tangent at 10 GHz to 40 GHz of the attached glass cloth of the present invention is preferably 0.002 or less, and more preferably 0.0015 or less. In addition, the change amount of the dielectric loss tangent needs to be small, and the ratio of 40 GHz/10 GHz is preferably 2.0 or less, and more preferably 1.6 or less. In particular, glass cloth used as a substrate used in high-speed communications such as 5G needs to have a low dielectric loss tangent.

The mass per unit area of the attached glass cloth of the present invention is preferably 4 to 300 g/m ² , more preferably 4 to 260 g/m ² .

The adhered glass cloth of the present invention can be suitably used as prepregs and printed wiring boards for printed circuit boards that seek low dielectric loss tangents, and is particularly suitable for use as multilayer printed circuit boards for high frequencies above 10 GHz.

Example

Hereinafter, Examples and Comparative Examples will be shown to explain the present invention in detail. However, the present invention is not limited to the following Examples.

The following methods were used to measure the dielectric loss tangent, calculate the dielectric loss tangent, the silanol group (Si-OH) content, the adhesion amount of the silane coupling agent, and evaluate the softening point and processability in the examples. .

[Measurement of dielectric loss tangent]

The dielectric constant was measured using SPDR (Split post dielectric resonators) dielectric resonators with frequencies of 10 GHz and 40 GHz.

In addition, the dielectric loss tangent of Examples and Comparative Examples represents the dielectric loss tangent of attached glass cloth.

[Measurement of silanol group (Si-OH) content]

The silanol content of glass fiber and glass cloth refers to a value measured and calculated using the following method.

For the infrared absorption spectrum of glass fiber and glass cloth, Fourier transform infrared spectrophotometer (IRAffini ty-1S) and diffuse reflectance measuring device (DRS-8000A) were used to measure the infrared absorption spectrum caused by silanol near 3680cm ^-1 using the diffuse reflectance method. The peak transmittance T. Based on the obtained transmittance value, the absorbance A was obtained by applying the Lambert-Beer law shown below.

Absorbance A＝-Log10T (Transmittance near T＝3680cm ^-1 )

Next, from the absorbance calculated based on the above equation, the molar concentration C (mol/L) of silanol is calculated based on the following equation.

C＝A/εL

ε: Molar absorption coefficient (molar absorption coefficient of silanol ε = 77.5dm ³ /mol·cm)

C: molar concentration (mol/L)

L: Thickness of sample (optical path length)

From the obtained absorbance A, the molar concentration C was determined using the above formula.

Using the obtained molar concentration C, the silanol content (ppm) in the glass fiber was calculated using the following formula.

Silanol content (ppm) = {(C×M(Si-OH))/(d×1000)}×106 Specific gravity of glass fiber d=2.2g/cm ³

The molecular weight of silanol M (Si-OH) = 45g/mol

[Measurement of adhesion rate of silane coupling agent]

The attached glass cloth was heated using an electric furnace at 625°C for 4 hours, and the mass change before and after heating was measured. Based on the following formula, the adhesion rate (mass %) was calculated.

Adhesion rate (mass %) = (mass of attached glass cloth before heating - mass of attached glass cloth after heating)/mass of attached glass cloth before heating × 100

[Measurement of softening point]

Using a thermomechanical analysis device (TMA), the glass fiber is stretched in the radial direction to measure the softening point.

[Evaluation of processability]

Prepregs were produced by impregnating attached glass cloth with epoxy resin, and wettability (unevenness) and drill life (drill life) were evaluated.

There is no problem with wettability (unevenness), and the drill life is more than 100 times: ○

There are problems with wettability (unevenness) or the drill bit life is less than 100 times: ×

[Examples 1 to 3]

The silica glass fiber with SiO ₂ mass % and softening point shown in Table 1 was stretched at high temperature while applying a sizing agent to prepare a silica glass strand consisting of 200 silica glass filaments with a diameter of 5.0 μm. Next, the obtained quartz glass yarn was twisted 0.4 times per 25 mm to prepare a quartz glass yarn.

The obtained quartz glass yarn was set on an air-jet loom to weave a flat-woven quartz glass cloth with a warp density of 54 yarns/25mm and a weft yarn density of 54 yarns/25mm. Then, the sizing agent was removed by thermal cleaning, and then treated with a silane coupling agent (KBM-503: methacryloyloxypropyltrimethoxysilane) so that the adhesion amount would be 0.1% by mass. The thickness of the obtained treated quartz glass cloth was 45 μm, and the cloth mass was 42.5 g/m ² . The evaluation results are shown in the table below.

[Example 4]

A glass cloth was prepared in the same manner as in Example 1, and was treated with a silane coupling agent (KBM-503) so as to have an adhesion amount of 0.2% by mass, thereby obtaining a treated quartz glass cloth.

[Example 5]

A glass cloth was prepared in the same manner as in Example 1, and was treated with a silane coupling agent (KBM-503) so as to have an adhesion amount of 0.05% by mass, thereby obtaining a treated quartz glass cloth.

[Comparative example 1]

Except using E glass fiber with a softening point of 800° C. and a SiO ₂ content of 53% by mass, a glass cloth was prepared in the same manner as in Example 1, and a silane coupling agent (KBM-503) was used so that the adhesion amount would be 0.1% by mass. ) was processed and the processed quartz glass cloth was obtained.

[Comparative example 2]

A glass cloth was prepared in the same manner as in Example 1 except that quartz glass fiber with a SiO ₂ content of 99.9 mass% and a Si-OH content greater than 1000 ppm was used, and a silane coupling agent ( KBM-503) was processed and the processed quartz glass cloth was obtained.

[Comparative example 3]

Except using quartz glass fiber with a SiO ₂ content of 99.9 mass % and a Si-OH content of less than 1000 ppm, a glass cloth was prepared in the same manner as in Example 1, and a silane coupling agent ( KBM-503) was processed and the processed quartz glass cloth was obtained.

[Comparative example 4]

The same quartz glass as in Example 1 with a SiO ₂ content of 99.9 mass % and a Si-OH content of less than 1000 ppm was used to prepare glass cloth (not treated with a silane coupling agent).

【Table 1】

Example 1 Example 2 Example 3 Example 4 Example 5 _SiO2 amount (mass %) 99.9 99.9 99.9 99.9 99.9 Silanol amount (ppm) less than 1000 less than 1000 less than 1000 less than 1000 less than 1000 Adhesion amount of silane treatment agent (%) 0.1 0.1 0.1 0.2 0.05 Softening point(℃) 1200 1050 1125 1200 1200 Processability ○ ○ ○ ○ ○ Dielectric loss tangent (10GHz) 0.0007 0.0010 0.0009 0.0010 0.0008 Dielectric loss tangent (40GHz) 0.001 0.0014 0.0013 0.0014 0.0011 Dielectric loss tangent ratio (40GHz/10GHz) 1.4 1.4 1.4 1.4 1.4

【Table 2】

Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 _SiO2 amount (mass %) 53 99.9 99.9 99.9 Silanol amount (ppm) - larger than 1000 less than 1000 less than 1000 Adhesion amount of silane treatment agent (%) 0.1 0.1 1.0 0 Softening point(℃) 800 990 1200 1200 Processability ○ ○ ○ × Dielectric loss tangent (10GHz) 0.0050 0.0014 0.0015 0.0007 Dielectric loss tangent (40GHz) 0.0083 0.0022 0.0022 0.0010 Dielectric loss tangent ratio (40GHz/10GHz) 1.7 1.6 1.5 1.4

As shown in Examples 1 to 5, the dielectric loss tangent from 10 GHz to 40 GHz of the glass cloth made of glass fiber according to the present invention is less than 0.002, and the ratio between 40 GHz and 10 GHz is less than 2.0.

As shown in Comparative Example 1, when glass fiber with a softening point of 800° C. is used, the dielectric loss tangent from 10 GHz to 40 GHz is larger than 0.002.

As shown in Comparative Example 2, when a glass fiber with a softening point of 990°C and a silanol content greater than 1000 ppm is used, the dielectric loss tangent at 10 GHz is less than 0.002, but the dielectric loss tangent at 40 GHz is less than 0.002. 0.002 large.

As shown in Comparative Example 3, when a glass fiber with a softening point of 1200°C and a silanol content of less than 1000 ppm is used, and the adhesion amount of the silane treatment agent is 1.0% by mass, the dielectric loss tangent at 10 GHz is less than 0.002, but at 40 GHz The dielectric loss tangent is greater than 0.002.

As shown in Comparative Example 4, when a glass fiber with a softening point of 1200° C. and a silanol content of less than 1000 ppm is used, and the adhesion amount of the silane treatment agent is 0%, the processability is poor.

Claims (5)

1. A glass cloth composed of glass fibers with a softening point of 1000 to 1600° C. and an amount of Si-OH groups of less than 1000 ppm adhered to the glass cloth in an amount of 0.001% by mass or more and less than 1.0% by mass relative to the glass cloth % silane coupling agent. 2. The glass cloth according to claim 1, wherein the dielectric loss tangent from 10 GHz to 40 GHz is 0.002 or less, and the dielectric loss tangent ratio of 40 GHz/10 GHz is 2.0 or less. 3. The glass cloth according to claim 1 or 2, wherein the amount of _SiO2 in the glass fiber is 99.9 mass% or more. 4. The glass cloth according to claim 1 or 2, having a thickness of 200 μm or less. 5. The glass cloth according to claim 1 or 2, wherein the mass per unit area is 4 to 300 g/m ² .