Glass cloth, prepreg, and printed circuit boards

Abstract

To provide a low dielectric glass cloth with both of variation in dielectric properties and strength degradation suppressed, and a prepreg and a printed wiring board made of the low dielectric glass cloth.SOLUTION: A glass cloth including a glass yarn made of a plurality of glass filaments as warp and weft has a weight loss factor obtained as a product of a weight loss ratio derived from the glass component in heat treatment at 380°C for 2 hours and an average radius of the glass filament in the following equation (1) of more than 0.45 and 0.90 or less. The glass cloth has an Fe content in terms of Fe2O3 of 0.001 mass% or more and 0.05 mass% or less. Weight loss factor=The weight loss ratio (%)×Average radius of the glass filament (μm) ... (1)SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] With the development of the information and communication society in recent years, data communication and / or signal processing have been carried out in large volumes and at high speeds, and the reduction of the dielectric constant of printed wiring boards used in electronic devices has been progressing significantly. Therefore, many low-dielectric glass cloths have been proposed for the glass cloth constituting the printed wiring board.

[0003] For example, the low-dielectric glass cloth disclosed in Patent Document 1 achieves a low dielectric constant by blending a large amount of B2O3 in the glass composition and simultaneously adjusting the blending amounts of other components such as SiO2 with respect to the E glass cloth that has been generally used conventionally.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the proportion of B2O3 contained in the glass fiber is increased to reduce the dielectric constant of the glass cloth, the elastic modulus of the glass fiber decreases, and the strength reduction of the glass cloth after heat treatment is significant. Therefore, there is a problem that the glass cloth is likely to break. When a prepreg is manufactured using such a glass cloth, the glass cloth breaks in a situation where an external load is applied to the glass cloth, such as an operation for controlling the resin adhesion amount, causing production problems.

[0006] In this regard, Patent Document 1 discloses a method for suppressing the volatilization of B2O3 during the spinning of glass yarn by reducing the B2O3 content to less than 20% by mass and the CaO content to a predetermined range. However, reducing the B2O3 content to less than 20% by mass is insufficient to meet the requirement for a low dielectric constant, and as a result, a glass cloth that is both low dielectric and has suppressed strength reduction has not been realized. Furthermore, it has become clear that if the weight loss during heat treatment is within a certain range, the strength reduction becomes even more severe.

[0007] Furthermore, it has become clear that when attempting to suppress volatilization by adding other components, as described in Patent Document 1, variations in dielectric properties may occur in the planar direction of the glass cloth or between lots.

[0008] This invention has been made in view of the above-mentioned problems, and aims to provide a low-dielectric glass cloth in which both variations in dielectric properties and reduction in strength are suppressed, as well as a prepreg and printed circuit board using the low-dielectric glass cloth. [Means for solving the problem]

[0009] As a result of diligent research to solve the above problems, the inventors of the present invention have found that by adjusting the Fe content in glass yarn having a predetermined weight reduction tendency, the glass cloth obtained using said glass yarn can solve the above problems, and have completed the present invention.

[0010] In other words, the present invention is as follows. [1] A glass cloth composed of glass threads made of multiple glass filaments as warp and weft threads, In the following formula (1), the weight loss coefficient, which is calculated as the product of the weight loss rate derived from the glass component during a heat treatment at 380°C for 2 hours and the average radius of the glass filament, is greater than 0.45 and less than or equal to 0.90. Weight reduction coefficient = the weight reduction ratio (%) × the average radius (μm) of the glass filament ··· (1) The Fe content of the glass cloth is 0.001% by mass or more and 0.05% by mass or less in terms of Fe2O3. Glass cloth. 〔2〕 For the glass cloth, the F content is 0.001 to 0.1% by mass. The glass cloth according to 〔1〕. 〔3〕 For the glass cloth, the Si content is 40 to 60% by mass in terms of SiO2, and the B content is 15 to 30% by mass in terms of B2O3. The glass cloth according to 〔1〕 or 〔2〕. 〔4〕 The elastic modulus of the glass cloth is 50 to 70 GPa. The glass cloth according to any one of 〔1〕 to 〔3〕. 〔5〕 The elastic modulus of the glass cloth is 50 to 63 GPa. The glass cloth according to 〔4〕. 〔6〕 The average diameters of the glass filaments constituting the warp and the weft are each independently 3.5 to 5.4 μm. The glass cloth according to any one of 〔1〕 to 〔5〕. 〔7〕 Having a dielectric constant of 5.0 or less at a frequency of 1 GHz. The glass cloth according to any one of 〔1〕 to 〔6〕. 〔8〕 The glass cloth according to any one of 〔1〕 to 〔7〕 and a matrix resin impregnated in the glass cloth, having Prepreg. 〔9〕 Comprising the glass cloth according to any one of 〔1〕 to 〔7〕 Printed wiring board.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a low dielectric glass cloth in which both the variation in dielectric properties and the reduction in strength are suppressed, and a prepreg and a printed wiring board using the low dielectric glass cloth.

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof.

[0013] 〔Glass Cloth〕 The glass cloth of the present embodiment is a glass cloth composed of glass yarns made of a plurality of glass filaments as warp and weft. In the following formula (1), the weight reduction coefficient obtained as the product of the weight reduction ratio derived from the glass component in the heat treatment at 380°C for 2 hours and the radius of the glass filament is more than 0.45 and not more than 0.90, and the Fe content of the glass cloth is 0.001 mass% or more and 0.05 mass% or less in terms of Fe2O3. Weight reduction coefficient = the weight reduction ratio (%) × the average radius (μm) of the glass filament ··· (1)

[0014] In a glass cloth having a low dielectric constant, the strength of the glass cloth decreases during the heat treatment in the manufacturing process or the heat treatment in the subsequent process. Due to this strength reduction and the low elastic modulus of the glass yarns constituting the low dielectric glass cloth, the low dielectric glass cloth is more likely to break compared to those using other glass yarns such as E glass. In contrast, in the present embodiment, in a glass loss having a predetermined weight reduction tendency, the content of Fe (iron) in the glass, and more preferably the content of F (fluorine) are adjusted to suppress the strength reduction due to heat treatment.

[0015] The reasons why adjusting the Fe content can suppress the decrease in strength are not limited to the following, but are thought to be the following: During spinning, even if sparse areas occur in the glass yarn, molten glass can flow to fill those areas, and the parts of the glass yarn that become sparse and brittle due to weight reduction can be resolved by this flow. On the other hand, even if sparse areas occur in the glass yarn that constitutes the glass cloth, the glass cannot flow to fill those areas. Under these circumstances, in the glass cloth of this embodiment, it is possible that the Fe incorporated into the glass structure acts to bind together the parts of the glass yarn that become sparse and brittle due to weight reduction.

[0016] Furthermore, the reasons why variations in dielectric properties can be suppressed by adjusting the Fe content are not limited to the following, but can be considered as follows. Glass fibers are basically composed of amorphous parts, but the parts where Fe is present can be considered to be relatively crystalline parts. Thus, when a part of the composition constituting the amorphous part of a glass fiber, in which locally crystalline parts exist within the amorphous part, volatilizes, it is thought that variations in dielectric properties will occur depending on how the crystalline parts are present. In particular, when the Fe content is excessive, it is thought that the variations in dielectric properties that occur in this way become more apparent, but in this embodiment, variations in dielectric properties can be suppressed by adjusting the Fe content. In particular, the lower the dielectric constant and dielectric loss tangent, the greater the effect of suppressing variations in dielectric properties by adjusting the Fe content tends to be.

[0017] Furthermore, the reasons why adjusting the F content further suppresses the decrease in strength are not limited to the following, but are thought to be the following: F reduces the viscosity of molten glass during the glass manufacturing process. Therefore, when the F content is within a predetermined range, metal components such as Fe are incorporated into the glass structure and dispersed uniformly without localization, forming a uniform glass. With the uniform dispersion of Fe, it is possible that the effect of Fe in binding together areas where the glass fibers become sparse due to the volatilization of the glass components is expressed more effectively. In addition, if Fe and other metals are localized, hard areas may be unevenly distributed in the glass, making it easier for fractures to occur starting from those areas. However, by adjusting the F content, it is thought that such localization can be mitigated, and the decrease in strength can be further suppressed.

[0018] Furthermore, the reasons why adjusting the F content further suppresses variations in dielectric properties are not limited to the following: As mentioned above, F reduces the viscosity of molten glass in the glass manufacturing process. Therefore, by adjusting the Fe content and keeping the F content within a predetermined range, the localized generation of relatively crystalline areas where Fe is present is greatly suppressed, resulting in the formation of a more uniform glass and thus suppressing variations in dielectric properties.

[0019] By having the above configuration, this embodiment solves the problem of breakage that low-dielectric glass cloths had, and provides a glass cloth with high break resistance and dielectric properties with low variability. The configuration of this embodiment will be described in more detail below.

[0020] (Weight reduction factor) The weight loss coefficient (hereinafter also simply referred to as the "weight loss coefficient"), which is calculated as the product of the weight loss rate derived from the glass component and the average radius of the glass filaments when glass cloth is heat-treated at 380°C for 2 hours, is greater than 0.45 and less than or equal to 0.90, preferably between 0.47 and 0.85, and more preferably between 0.48 and 0.80.

[0021] "Weight loss percentage due to glass components" means that the weight loss percentage after heat treatment at 380°C for 2 hours is due to the loss of glass components due to volatilization during the heat treatment. As described later, in this embodiment, if surface treatment agents such as silane coupling agents or a large amount of organic impurities are attached to the glass cloth, the weight loss percentage is calculated after removing the surface treatment agents such as silane coupling agents and organic impurities that are physically adsorbed with a good solvent such as alcohol or acetone. Therefore, the weight loss percentage of the glass cloth after heat treatment, after removing such adhering components that decompose at 380°C, is the weight loss percentage due to glass components.

[0022] Furthermore, it was confirmed that this weight reduction rate depends on the filament diameter of the glass fiber. The weight reduction rate differs depending on the glass filament diameter, with smaller filament diameters resulting in greater weight reduction. On the other hand, the product of the weight reduction rate and the filament radius is approximately constant regardless of the filament diameter. Therefore, in this embodiment, the weight reduction coefficient is normalized by the filament diameter.

[0023] A weight loss coefficient exceeding 0.45 makes it prone to strength reduction. However, by adjusting the Fe content as described later, strength reduction can be suppressed in this embodiment, and a glass cloth with a lower dielectric constant can also be obtained due to the composition of the glass cloth. Furthermore, a weight loss coefficient of 0.90 or less allows the strength reduction suppression effect of Fe to work effectively, preventing significant strength reduction.

[0024] The weight loss percentage can be measured using the following procedure. First, the glass cloth is dried in a dryer at 105°C ± 5°C for 60 minutes, then transferred to a desiccator and allowed to cool to room temperature. After cooling, the weight of the glass cloth is measured to a unit of 0.1 mg or less (glass cloth weight a). Next, the glass cloth is heated at 380°C for 2 hours, then transferred to a desiccator and allowed to cool to room temperature. After cooling, the weight of the glass cloth is measured to a unit of 0.1 mg or less (glass cloth weight b after heat treatment). Then, the weight lost due to the heat treatment is determined, and the weight loss percentage (%) is calculated using the following formula (2). Weight reduction rate (%) = (ab) / a×100 ···(2)

[0025] The weight reduction rate obtained as described above is preferably 0.05 to 0.7%, more preferably 0.1 to 0.5%, and even more preferably 0.12 to 0.4%. A weight reduction rate of 0.05% or more is likely to cause a decrease in strength. However, by adjusting the Fe content, as described later, and more preferably by also adjusting the F content, in this embodiment, a decrease in strength can be suppressed, and a glass cloth with a lower dielectric constant can be obtained due to the composition of the glass cloth. Furthermore, by having a weight reduction rate of 0.7% or less, the strength reduction suppression effect of Fe is effectively at work, and a significant decrease in strength can be suppressed.

[0026] Next, the average diameter of the glass filaments of the glass thread constituting the glass cloth is measured in accordance with JIS R3420, and the average filament diameter is determined by taking half of the said filament diameter. In this embodiment, when simply referred to as glass filament, it means glass monofilament. The average radius of the glass filament used in calculating the weight loss coefficient is the average radius before heat treatment. The average radius of the glass filament thus obtained is preferably 1.25 to 4.5 μm, more preferably 1.5 to 3.75 μm, and even more preferably 1.75 to 2.7 μm.

[0027] Furthermore, the glass cloth used in the weight loss rate measurement method described above can be pre-treated as appropriate. For example, glass cloth pulled from an intermediate roll after de-adhesive treatment (heat cleaning) can be used directly in the weight loss rate measurement method described above because no adhering material is attached to the glass filaments.

[0028] On the other hand, when determining the weight loss ratio for glass cloth coated with a surface treatment agent such as a silane coupling agent, the surface treatment agent such as the silane coupling agent that has been physically adsorbed can be removed beforehand using a suitable solvent such as alcohol or acetone, and then the weight loss coefficient can be determined using the method described above.

[0029] Furthermore, "physically adsorbed silane coupling agents" refer to silane coupling agents that are attached to glass filaments and not silane coupling agents that are chemically bonded to the glass filaments. In contrast, silane coupling agents that are chemically bonded to glass filaments are called "chemically adsorbed silane coupling agents."

[0030] Furthermore, if the glass cloth contains organic impurities (such as starch-based sizing agents applied during the glass yarn manufacturing process, or combustion residues from the heat cleaning process of the sizing agent), the weight loss coefficient can be determined using the method described above after removing the organic impurities adhering to the glass cloth by a washing and removal operation using alcohols, acetone, etc.

[0031] The above cleaning process removes physically adsorbed silane coupling agents and organic impurities, but does not remove chemically adsorbed silane coupling agents. However, even if heated at 380°C for 2 hours, the chemically adsorbed silane coupling agents will not decompose, or if some decompose, it will not exceed the margin of error. Therefore, in measuring the weight loss rate in this embodiment, it is not necessary to remove the chemically adsorbed silane coupling agents in the pretreatment.

[0032] Furthermore, to simplify the decision of whether or not to perform pretreatment, glass cloth that has been uniformly washed in advance with a suitable solvent such as alcohol or acetone may be used for measuring the weight loss rate. This allows for the measurement of the weight loss rate to be performed under the same conditions, whether the glass cloth is pulled from an intermediate roll after de-adhesion treatment (heat cleaning) or whether it has physically adsorbed silane coupling agents or organic impurities attached to it.

[0033] Alternatively, when determining the weight loss coefficient mentioned above, the amount of surface treatment agent and organic impurities before and after heating can be quantified, and the weight loss due to the surface treatment agent can be subtracted from the obtained weight loss to determine the weight loss coefficient derived from the glass components. As a method for determining the weight loss due to the surface treatment agent, known methods such as the quantitative determination method for silane coupling agents described in Japanese Patent Publication No. 6472082 may be used.

[0034] The weight loss coefficient can be adjusted by increasing or decreasing relatively volatile components in the composition of the glass cloth, such as the B content, and can also be adjusted by increasing or decreasing other components from a similar perspective.

[0035] Furthermore, the weight reduction coefficient can also be adjusted by increasing or decreasing the opportunities for the glass surface to be exposed to a high-temperature atmosphere through adjustments such as adjusting the void filling rate of glass in the glass cloth (weaving density and thickness), adjusting the degree of unraveling of the monofilaments constituting the glass yarn bundle through processes such as fiber opening, and adjusting the monofilament diameter of the glass yarn used. In other words, the weight loss coefficient is not determined solely by the composition of the glass cloth.

[0036] (composition) The composition of the glass cloth in this embodiment will be described below. Note that the composition of the glass cloth is synonymous with the composition of the glass yarn that constitutes the glass cloth. In the composition of the glass cloth in this embodiment, the Fe content is 0.001% by mass or more and 0.05% by mass or less, preferably 0.01% by mass or more and 0.04% by mass or less, and more preferably 0.01% by mass or more and 0.03% by mass or less, based on Fe2O3. By having an Fe content of 0.001% by mass or more, the decrease in strength due to heat treatment of the glass cloth can be suppressed. Furthermore, by having an Fe content of 0.05% by mass or less, the necessary strength can be maintained even in glass cloths that are prone to a weight loss coefficient exceeding 0.45 and a decrease in strength. Furthermore, by having an Fe content of 0.05% by mass or less, in-plane variation and lot-to-lot variation of dielectric constant can be suppressed. The Fe content can be adjusted according to the amount of raw material used in the production of the glass filament.

[0037] The Si content of the glass cloth is preferably 40-60% by mass, more preferably 45-55% by mass, even more preferably 47-53% by mass, and 48-52% by mass, in terms of SiO2. Si is a component that forms the skeletal structure of glass yarn, and a Si content of 40% by mass or more suppresses the decrease in strength due to heat treatment, as well as further improves the strength of the glass yarn itself before heat treatment, which tends to further suppress the breakage of the glass cloth in the glass cloth manufacturing process and in subsequent processes such as the production of prepregs using glass cloth. In addition, a Si content of 40% by mass or more tends to further lower the dielectric constant of the glass cloth. On the other hand, a Si content of 60% by mass or less tends to further lower the viscosity during melting in the glass filament manufacturing process, resulting in the acquisition of glass fibers with a more homogeneous glass composition. As a result, areas that are easily penetrated or areas where air bubbles are difficult to escape are less likely to occur in the resulting glass filament, making it less likely for locally weak areas to occur in the glass filament, and as a result the glass cloth composed of glass yarn obtained using this becomes less prone to breakage. The Si content can be adjusted according to the amount of raw materials used in the production of the glass filament.

[0038] The B content of the glass cloth is preferably 15-30% by mass, more preferably 17-28% by mass, even more preferably 20-27% by mass, even more preferably 21-25% by mass, and even more preferably 21-24% by mass, based on B2O3. A B content of 15% by mass or more tends to further reduce the dielectric constant. Furthermore, a B content of 30% by mass or less suppresses the reduction in strength, improves moisture resistance, and tends to further improve insulation reliability. The B content can be adjusted according to the amount of raw materials used in the production of the glass filament. If the B content may fluctuate during the production of the glass filament, the amount of raw materials added can be adjusted in advance to account for this.

[0039] The F content of the glass cloth is preferably 0.001 to 0.1% by mass, more preferably 0.001 to 0.05% by mass, and even more preferably 0.001 to 0.01% by mass. Here, the F content is a value obtained in terms of F2. When the F content is 0.001% by mass or more, the decrease in strength due to heat treatment of the glass cloth is further suppressed, and the dielectric constant tends to decrease further. Also, F reduces the viscosity of the molten glass in the glass manufacturing process. Therefore, when the F content is within the predetermined range, when metal components such as Fe are incorporated into the glass structure, they are uniformly dispersed without localization, and a uniform glass can be formed. The effect of Fe tends to be fully exhibited. When the F content is 0.1% by mass or less, it is possible to suppress the decrease in the strength of the glass yarn itself before heat treatment that can occur when the F content is too high. Also, by setting both the Fe content and F content within the above predetermined range, the effect of suppressing the decrease in strength due to heat treatment tends to be further improved. The F content can be adjusted according to the amount of raw material used in the production of the glass filament.

[0040] Furthermore, while there is no particular limit to the reduction in strength due to excessive fluorine content, the following can be considered: As the fluorine content increases, the phase separation of the glass composition becomes stronger, making it more difficult to homogenize the glass components.

[0041] Furthermore, the glass cloth may have other compositions besides those mentioned above. These other compositions are not particularly limited, but examples include Al, Ca, Mg, P, Na, K, Ti, and Zn.

[0042] The Al content of the glass cloth is preferably 10-20% by mass, more preferably 12-18% by mass, and even more preferably 14-17% by mass, based on Al2O3. Having an Al content within this range tends to improve electrical properties and strength. The Al content can be adjusted according to the amount of raw material used in the production of the glass filament.

[0043] The Ca content of the glass cloth is preferably 1.0 to 6.0% by mass, preferably 2.0 to 5.0% by mass, and more preferably 2.5 to 4.0% by mass. A Ca content of 1.0% by mass or more tends to reduce the viscosity during melting in the glass filament manufacturing process, resulting in glass fibers with a more homogeneous glass composition. Furthermore, a Ca content of 6.0% by mass or less tends to improve the dielectric constant. The Ca content can be adjusted according to the amount of raw materials used in the glass filament production.

[0044] The Mg content of the glass cloth is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 0.001 to 1.0% by mass or less, even more preferably 0.005 to 0.5% by mass or less, and even more preferably 0.005 to 0.3% by mass or less, in terms of MgO. A Mg content of 5.0% by mass or less is preferable because it suppresses phase separation during glass filament manufacturing, resulting in a more uniform glass composition and a tendency to reduce variations in dielectric properties.

[0045] Furthermore, suppressing phase separation during glass filament manufacturing improves the moisture resistance of the resulting glass filament. As a result, the resulting printed circuit board is less susceptible to the effects of high-humidity environments, and the environmental dependence of the dielectric constant can be reduced. The Mg content can be adjusted according to the amount of raw materials used in glass filament production.

[0046] The phosphorus (P) content of the glass cloth is preferably 1.0 to 7.0% by mass, more preferably 2.0 to 6.5% by mass, even more preferably 3.0 to 6.0% by mass, and even more preferably 3.0 to 5.5% by mass, based on P2O5. A P content of 1.0% by mass or more tends to further reduce the dielectric constant. Furthermore, a P content of 7.0% by mass or less tends to reduce the likelihood of breakage when the glass cloth passes through squeeze rolls or nip rolls while wet during processes such as fiber opening and surface treatment during glass cloth manufacturing. In addition, phase separation during glass filament manufacturing is suppressed, and the moisture resistance of the resulting glass filament is further improved. As a result, the resulting printed circuit board is less affected by high humidity environments, and the environmental dependence of the dielectric constant can be reduced. The P content can be adjusted according to the amount of raw materials used in glass filament production.

[0047] The above-mentioned content can be measured by ICP emission spectrometry. Specifically, the Si and B content can be obtained by pressurizing and decomposing a weighed glass cloth sample with sodium hydroxide, then dissolving it in dilute nitric acid and filtering it. The undissolved portion is then dissolved with sodium carbonate, and the mixture is combined with the filtrate to a fixed volume. The resulting sample is then measured by ICP emission spectrometry.

[0048] The Fe, Al, Ca, Ma, and P content are determined by heating and decomposing a weighed glass cloth sample with perchloric acid, nitric acid, hydrochloric acid, and hydrogen fluoride, then heating and dissolving it with dilute aqua regia and filtering it. The filtrate is then brought to a fixed volume. Undissolved components are then heated and decomposed with sulfuric acid, nitric acid, hydrochloric acid, and hydrogen fluoride to achieve a fixed solution, and the resulting sample is measured by ICP emission spectrometry. A Hitachi High-Tech Science PS3520VDD II ICP emission spectrometer can be used.

[0049] Furthermore, the fluoride content is determined by burning a weighed glass cloth sample in a tubular electric furnace, and then absorbing the resulting gas into an absorption solution. This solution is then analyzed by ion chromatography to determine the fluoride ions (F). - The amount of the substance in the sample can be determined by measuring its concentration. The combustion device can be an automated sample combustion device (AQF-2100S) manufactured by Mitsubishi Chemical Analytec, and the measuring device can be an ion chromatograph ICS-1500 manufactured by Thermo Fisher Scientific.

[0050] The elastic modulus of the glass cloth is preferably 50 to 70 GPa, more preferably 50 to 63 GPa, and even more preferably 53 to 63 GPa. The lower the elastic modulus of the glass cloth, the more likely it is to break. Therefore, an elastic modulus of 50 GPa or higher tends to reduce the likelihood of breakage when the glass cloth passes through squeeze rolls or nip rolls while wet during manufacturing processes such as fiber opening and surface treatment. Furthermore, in subsequent processes such as prepreg manufacturing, breakage tends to be reduced when the glass cloth is passed through slits to control the amount of resin impregnation into the glass cloth. An elastic modulus of 70 GPa or lower results in a softer texture, and reduces the likelihood of breakage when the glass cloth passes through narrow gaps such as squeeze rolls or nip rolls. Additionally, an elastic modulus of 70 GPa or lower tends to result in a relatively lower dielectric constant. The elastic modulus can be measured by the method described in the examples. The elastic modulus can also be adjusted by the composition of the glass yarn.

[0051] The dielectric constant of the glass cloth in this embodiment is preferably 5.0 or less, more preferably 4.7 or less, even more preferably 4.5 or less, and particularly preferably 4.0 or less at a frequency of 1 GHz. The lower the dielectric constant of the glass cloth, the greater the influence of the Fe content, and the more useful the present invention becomes. In this embodiment, unless otherwise specified, the dielectric constant refers to the dielectric constant at a frequency of 1 GHz.

[0052] (composition) Glass yarn is obtained by bundling multiple glass filaments together and twisting them as needed, while glass cloth is obtained by weaving the above glass yarn as warp and weft threads. Glass yarn is classified as multifilament, and glass filaments are classified as monofilament.

[0053] The average diameter of the glass filaments constituting the warp and weft threads is preferably 2.5 to 9 μm, more preferably 3.0 to 7.5 μm, and even more preferably 3.5 to 5.4 μm, respectively. Having the average diameter of the glass filaments within this range tends to improve processability when processing the resulting substrate with a mechanical drill, carbon dioxide laser, or UV-YAG laser. This allows for the realization of thin, high-density mounted printed circuit boards. In particular, when the average diameter is 5.4 μm or less, the increased surface area per unit volume makes it more susceptible to strength reduction due to heat treatment, making the strength reduction suppression effect of this embodiment even more important. Furthermore, having an average diameter of 2.5 μm or more reduces the surface area, suppressing the volatilization of glass components. Additionally, during glass cloth manufacturing processes such as fiber opening and surface treatment, breakage is less likely to occur when the glass cloth passes through squeeze rolls or nip rolls while wet. Furthermore, in subsequent processes such as prepreg manufacturing, when passing the glass cloth through slits to control the amount of resin impregnation into the glass cloth, breakage tends to be less likely to occur.

[0054] The density of the warp and weft threads constituting the glass cloth is preferably 30 to 120 threads / 25 mm, more preferably 40 to 110 threads / 25 mm, and even more preferably 50 to 100 threads / 25 mm.

[0055] The thickness of the glass cloth is preferably 8 to 100 μm, more preferably 10 to 50 μm, even more preferably 12 to 35 μm, and particularly preferably 12 to 20 μm. A glass cloth thickness within the above range tends to yield a thin yet relatively strong glass cloth. In particular, a thickness of 8 μm or more reduces the proportion of glass filaments near the surface of the glass cloth, thus reducing the amount of glass component volatilization. Conversely, a thickness of 100 μm or less increases the proportion of glass filaments near the surface of the glass cloth, making it more susceptible to strength reduction due to increased glass component volatilization, thus highlighting the strength reduction suppression effect of the present invention. Note that the weight loss coefficient depends on the diameter of the filaments constituting the glass cloth and is therefore less dependent on the thickness. This tendency is maintained at least within the above thickness range.

[0056] The weight (basis weight) of the glass cloth is preferably 8 to 250 g / m². 2 More preferably 8-100 g / m² 2 And more preferably 8-50 g / m 2 The g / m² g / m² is particularly preferably 8-35 g / m². 2 That is the case.

[0057] The weaving structure of the glass cloth is not particularly limited, but examples include plain weave, twill weave, satin weave, and twill weave. Among these, the plain weave structure is more preferred.

[0058] (Surface treatment) The glass cloth may be surface-treated with a surface treatment agent. The surface treatment agent is not particularly limited, but examples include silane coupling agents, and may be used in combination with water, organic solvents, acids, dyes, pigments, surfactants, etc., as needed.

[0059] The silane coupling agent is not particularly limited, but examples include the compound shown in formula (1). X(R) 3-n SiY n ...(1) (In formula (1), X is an organic functional group having at least one amino group and one unsaturated double bond group, Y is independently an alkoxy group, n is an integer between 1 and 3, and R is independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.)

[0060] X is preferably an organic functional group having at least three amino groups and unsaturated double bond groups, and more preferably an organic functional group having at least four amino groups and unsaturated double bond groups.

[0061] Any form of the alkoxy group described above can be used, but from the viewpoint of stabilizing the treatment on glass cloth, an alkoxy group with 5 or fewer carbon atoms is preferred.

[0062] Specifically, silane coupling agents include 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, N-β Examples include known individual elements or mixtures thereof such as -(N-benzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-benzylaminoethyl)-γ-aminopropyltriethoxysilane and its hydrochloride, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, and acryloxypropyltrimethoxysilane.

[0063] 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 two or more silane coupling agents with different molecular weights. By treating the surface of the glass yarn with two or more silane coupling agents with different molecular weights, the density of the surface treatment agent on the surface of the glass cloth increases, and the reactivity with the matrix resin tends to improve further.

[0064] [Method for manufacturing glass cloth] The method for manufacturing glass cloth in this embodiment is not particularly limited, but examples include a weaving step of weaving glass yarn to obtain glass cloth and a fiber opening step of opening the glass yarn of the glass cloth. Furthermore, if necessary, the method may also include a desizing step to remove sizing agents adhering to the glass yarn of the glass cloth and a surface treatment step using a silane coupling agent.

[0065] The weaving method is not particularly limited as long as it involves folding the warp and weft threads to achieve a predetermined weave structure. The fiber opening method is also not particularly limited, but examples include methods using spray water (high-pressure water opening), a vibro-washer, ultrasonic water, or a mangle. Furthermore, the desizing method is not particularly limited, but examples include methods that remove the sizing agent by heating. The surface treatment method involves contacting the glass cloth with a surface treatment agent containing a silane coupling agent and then drying it. Contact with the glass cloth by the surface treatment agent can be achieved by immersing the glass cloth in the surface treatment agent, or by applying the surface treatment agent to the glass cloth using a roll coater, die coater, or gravure coater. The drying method for the surface treatment agent is not particularly limited, but examples include hot air drying or drying using electromagnetic waves.

[0066] [Prepreg] The prepreg of this embodiment comprises the glass cloth and a matrix resin composition impregnated into the glass cloth. The prepreg having the glass cloth is less prone to strength reduction and has a high yield of the final product. Furthermore, it can provide a printed circuit board that has excellent dielectric properties and excellent moisture resistance, resulting in minimal fluctuations in dielectric constant due to the influence of the operating environment, especially in high humidity environments.

[0067] The prepreg of this embodiment can be manufactured according to conventional methods. For example, it can be manufactured by impregnating the glass cloth of this embodiment with a varnish in which a matrix resin such as epoxy resin is diluted with an organic solvent, then evaporating the organic solvent in a drying oven to cure the thermosetting resin to the B stage (semi-cured state).

[0068] Examples of matrix resin compositions include, in addition to the epoxy resins mentioned above, thermosetting resins such as bismaleimide resins, cyanate ester resins, unsaturated polyester resins, polyimide resins, BT resins, and functionalized polyphenylene ether resins; thermoplastic resins such as polyphenylene ether resins, polyetherimide resins, all-aromatic polyester liquid crystal polymers (LCPs), polybutadiene, and fluororesins; and mixed resins thereof. From the viewpoint of improving dielectric properties, heat resistance, solvent resistance, and press moldability, a resin obtained by modifying a thermoplastic resin with a thermosetting resin may be used as the matrix resin composition.

[0069] Furthermore, the matrix resin composition may contain inorganic fillers such as silica and aluminum hydroxide; flame retardants such as bromine-based, phosphorus-based, or metal hydroxide-based agents; other silane coupling agents; heat stabilizers; antistatic agents; ultraviolet absorbers; pigments; colorants; lubricants, etc.

[0070] [Printed wiring board] The printed circuit board of this embodiment is equipped with the above-mentioned glass cloth. The printed circuit board of this embodiment is less prone to strength reduction and has a high yield of final products. Furthermore, because it has excellent dielectric properties and excellent moisture resistance, it can also have the effect of being less affected by the operating environment, especially in high humidity environments, where the dielectric constant fluctuates less. [Examples]

[0071] The present invention will be described more specifically below using examples and comparative examples. The present invention is not limited in any way by the following examples.

[0072] [Physical properties of glass cloth] The physical properties of the glass cloth, specifically the thickness of the glass cloth, the diameter and number of filaments constituting the warp and weft threads, and the weave density of the warp and weft threads were measured in accordance with JIS R3420.

[0073] [Weight reduction coefficient] The weight loss coefficient was measured using the following procedure. First, the glass cloth pulled from the intermediate roll was placed in a dryer at 105°C ± 5°C and dried for 60 minutes. After that, the glass cloth was transferred to a desiccator and allowed to cool to room temperature. After cooling, the weight of the glass cloth was measured to the nearest 0.1 mg (weight of glass cloth a). Next, the glass cloth was heated at 380°C for 2 hours, and then transferred to a desiccator and allowed to cool to room temperature. After cooling, the weight of the glass cloth was measured to the nearest 0.1 mg (weight of glass cloth after heat treatment b). The weight reduction due to the heat treatment was then determined, and the weight reduction percentage (%) was calculated using the following formula (2). Weight reduction rate (%) = (ab) / a×100 ···(2)

[0074] Next, the diameter of the monofilament was measured in accordance with Method B of JIS R3420, and half of that value was taken as the radius of the monofilament. Although Method B of JIS R3420 specifies measuring the diameter of 25 filament cross-sections at random, the diameter of all monofilaments constituting the glass fiber (multifilament) was measured, and the average value was used to determine the filament diameter. The weight loss coefficient was calculated using the weight loss percentage (%) and the average radius of the glass filament (μm) from the following formula (1). Weight loss coefficient = Weight loss rate (%) × Average radius of glass filament (μm) ... (1)

[0075] [Elastic modulus] The elastic modulus was measured using the pulse echo overlap method with glass bulk as the test specimen.

[0076] [Strength reduction confirmation test] Using the glass cloths obtained in the examples and comparative examples, prepregs were prepared under the following conditions and evaluated for sufficient strength. The glass cloths were continuously drawn out and transported while being immersed in varnish, and the amount of varnish applied was adjusted by passing them through a slit. Next, they were dried in a drying oven at 120°C to obtain prepregs. The varnish used contained 65 parts by mass of methacrylated polyphenylene ether, 35 parts by mass of triallyl isocyanurate, 10 parts by mass of hydrogenated styrene thermoplastic elastomer, 25 parts by mass of brominated flame retardant, 65 parts by mass of spherical silica, 1 part by mass of organic peroxide, and 210 parts by mass of toluene.

[0077] For each example and comparative example, ten 2000m product rolls of glass cloth were prepared using the method described above. Based on these preparation results, the reduction in strength was confirmed according to the following evaluation criteria. A: If the glass cloth could be used to produce a prepreg using 10 rolls of glass cloth without breaking, it was determined that the glass cloth was superior in terms of productivity and handling. B: In the prepreg manufacturing process, if one roll of glass cloth breaks, but the remaining nine rolls do not break, the prepreg can be manufactured successfully. In this case, the glass cloth is judged to have practical strength. C: In the prepreg manufacturing process, if 2-3 rolls of glass cloth break, but the remaining rolls do not break, and the prepreg can be manufactured successfully, the glass cloth is judged to require strength improvement. D: During the prepreg manufacturing process, breakage occurred in four or more glass cloth rolls.

[0078] [Evaluation of the variation in dielectric loss tangent] From the prepregs prepared using the glass cloth obtained in the examples and comparative examples, 100 test pieces for electrical property measurement were arbitrarily prepared, and the dielectric loss tangent was measured. Based on the measurement results, the variation in dielectric loss tangent was evaluated according to the following evaluation criteria. A: No test specimens showed a dielectric loss tangent of 0.0028 or higher. B: One test specimen showed a dielectric loss tangent of 0.0028 or greater. There were 2-3 test specimens showing a dielectric loss tangent of C: 0.0028 or higher. There were four or more test specimens showing a dielectric loss tangent of D: 0.0028 or higher.

[0079] The prepregs were prepared using the same method as the strength reduction method. Test specimens for electrical property measurement were prepared using the following method: A predetermined number of prepregs were stacked so that the thickness of the laminate was approximately 1 mm, and then copper foil (manufactured by Furukawa Electric Industry Co., Ltd., 18 μm thick, GTS-MP foil) was placed on both sides of the stacked prepregs. A copper-clad laminate was obtained by vacuum pressing. Next, a laminate was obtained by removing the copper foil from the copper-clad laminate by etching.

[0080] From the resulting laminate, test pieces approximately 50 mm long and 1.5 mm wide were cut out so that the warp threads of the glass cloth were on the longer side, and these were used as test pieces for electrical property testing.

[0081] The dielectric loss tangent was measured using the following method: Test specimens for electrical property measurement were placed in an oven at 105°C ± 2°C and dried for 2 hours. After that, they were left to stand in a constant temperature chamber at 23 ± 2°C and 50 ± 5% relative humidity for 96 hours, and the dielectric constant at 10 GHz was measured. The measurement equipment used was a network analyzer (N5230A, Agilent Technologies) and a cavity resonator (Cavity Resornator CP series) manufactured by Kanto Electronics Applied Development Co., Ltd., and the measurements themselves were performed in an environment of 23 ± 2°C and 50 ± 5% relative humidity.

[0082] [Composition of glass cloth] The composition of the glass cloth was determined by ICP emission spectrometry. Specifically, the Si and B content were obtained by pressurizing and decomposing the weighed glass cloth sample with sodium hydroxide, then dissolving it in dilute nitric acid and filtering it. Undissolved components were dissolved with sodium carbonate, and the mixture was combined with the filtrate to a fixed volume. The resulting sample was then measured by ICP emission spectrometry.

[0083] Furthermore, the Fe, Al, Ca, Ma, and P content were determined by heating and decomposing the weighed glass cloth samples with perchloric acid, nitric acid, hydrochloric acid, and hydrogen fluoride, then heating and dissolving them with dilute aqua regia and filtering. The filtrate was then brought to a constant volume. Undissolved components were heated and decomposed with sulfuric acid, nitric acid, hydrochloric acid, and hydrogen fluoride to achieve a constant solution, and the resulting samples were measured by ICP emission spectrometry. A Hitachi High-Tech Science Corporation PS3520VDD II ICP emission spectrometer was used.

[0084] Furthermore, the fluoride content was determined by burning a weighed glass cloth sample in a tubular electric furnace, and then absorbing the resulting gas into an absorption solution. This solution was then analyzed by ion chromatography to determine the fluoride ion content (F). - The concentration of the substance in the sample was determined by measuring its concentration. The combustion device used was an automated sample combustion device (AQF-2100S) manufactured by Mitsubishi Chemical Analytec, and the measurement device was an ion chromatograph ICS-1500 manufactured by Thermo Fisher Scientific.

[0085] [Example 1] Using an air jet chamber, low-dielectric glass yarn consisting of 50 filaments with an average filament diameter of 4.0 μm was woven to obtain a glass cloth with a warp and weft density of 94 threads / 25 mm and a thickness of 14 μm. Next, the cloth was desizing treatment by heating to obtain an intermediate roll of glass cloth with a width of 1280 mm and a length of 2000 m. Subsequently, a fiber-opening process was performed using high-pressure water spray, and a surface treatment using a silane coupling agent was performed to produce a roll of glass cloth. The composition of the obtained glass cloth is shown in Table 1.

[0086] [Examples 2-5] A roll of glass cloth was obtained in the same manner as in Example 1, except that the composition of the glass fibers was different. The composition of the obtained glass cloth is shown in Table 1.

[0087] [Example 6] A roll of glass cloth was obtained in the same manner as in Example 1, except that glass yarn having the same composition as in Example 2 was used, and the degree of fiber opening was reduced by shortening the time in the fiber opening process and weakening the spray pressure. The composition of the obtained glass cloth is shown in Table 1.

[0088] [Comparative Examples 1-6] A roll of glass cloth was obtained in the same manner as in Example 1, except that the composition of the glass fibers was different. The composition of the obtained glass cloth is shown in Table 2.

[0089] [Comparative Example 7] A roll of glass cloth was obtained in the same manner as in Example 2, except that glass yarn having the same composition as in Example 2 was used, and the degree of fiber opening was increased by extending the time in the fiber opening process and increasing the spray pressure. The composition of the obtained glass cloth is shown in Table 2.

[0090] [Example 7] A roll of glass cloth was obtained in the same manner as in Example 1, except that a low-dielectric glass yarn consisting of 200 filaments with an average filament diameter of 5.0 μm was woven using an air jet chamber, and the warp and weft thread density was 69 threads / 25 mm, and the thickness was 30 μm. The composition of the obtained glass cloth was shown in Table 1.

[0091] [Example 8] A roll of glass cloth was obtained in the same manner as in Example 7, except that the warp and weft thread density was set to 55 threads / 25 mm, respectively. The composition of the obtained glass cloth was as shown in Table 1.

[0092] [Comparative Example 8] A roll of glass cloth was obtained in the same manner as in Example 8, except that the degree of fiber opening was increased by extending the time in the fiber opening process and increasing the spray pressure. The composition of the obtained glass cloth is shown in Table 2.

[0093] [Example 9] A roll of glass cloth was obtained in the same manner as in Example 1, except that a low-dielectric glass yarn consisting of 200 filaments with an average filament diameter of 7.0 μm was woven using an air jet chamber, and the warp and weft thread density was 60 threads / 25 mm, and the thickness was 92 μm. The composition of the obtained glass cloth was shown in Table 1.

[0094] [Reference example 1] A roll of glass cloth was obtained in the same manner as in Example 1, except that glass yarn with an E-glass composition was used. The composition of the obtained glass cloth was shown in Table 2.

[0095] [Table 1]

[0096] [Table 2]

[0097] In Examples 1-3 and 6-9, all 10 rolls of glass cloth could be manufactured stably without any breakage (Evaluation A). In Examples 4 and 5, only one roll of glass cloth broke, but the remaining 9 rolls could be manufactured stably (Evaluation B). Furthermore, although the glass cloth in Reference Example 1 did not experience breakage or variations in dielectric loss tangent, its electrical properties were inferior, indicating that breakage and variations in dielectric loss tangent are particularly common problems with low-dielectric glass cloth.

[0098] On the other hand, the glass cloths of Comparative Examples 1, 2, and 5-8 experienced breakage in 2 or 3 rolls (Evaluation C). This is insufficient for stably supplying printed circuit boards using low-dielectric glass, and improvement is necessary. Furthermore, the glass cloths of Comparative Examples 3-4 experienced breakage in 4 rolls consecutively from the start of coating, forcing the coating test to be stopped (Evaluation D).

[0099] The dielectric loss tangent of the printed circuit boards evaluated using the glass cloths of Examples 1, 2, and 4-9 was less than 0.0028 in all cases, indicating that they were very reliable glass cloths (Evaluation A). The glass cloth of Example 3 showed a dielectric loss tangent of 0.0028 or higher in only one sample, indicating that it was a relatively reliable glass cloth (Evaluation B). On the other hand, the glass cloths of Comparative Examples 3 and 4 showed a dielectric loss tangent of 0.0028 or higher in four or more samples, indicating that they were less reliable glass cloths (Evaluation D).

[0100] In addition, while the examples and comparative examples all had a dielectric constant of approximately 3.0 and were low-dielectric glass cloths, Reference Example 1 had a dielectric constant of approximately 5.1 and could not be considered a low-dielectric glass cloth. [Industrial applicability]

[0101] The present invention has industrial applicability as a low-dielectric glass cloth used in prepregs and the like.

Claims

1. A glass cloth composed of glass threads made of multiple glass filaments as warp and weft threads, In the following formula (1), the weight loss coefficient, which is calculated as the product of the weight loss rate derived from the glass component during a heat treatment at 380°C for 2 hours and the average radius of the glass filament, is greater than 0.45 and less than or equal to 0.

90. Weight reduction coefficient = Weight reduction rate (%) × Average radius of the glass filament (μm) ... (1) The Fe content of the glass cloth is Fe 2 O 3 In terms of conversion, it is between 0.001% by mass and 0.05% by mass. Having a dielectric constant of 5.0 or less at a frequency of 1 GHz, The glass cloth has a Si content of 40 to 60% by mass in terms of SiO₂, and a B content of 15 to 30% by mass in terms of B₂O₃. Glass cloth.

2. The aforementioned glass cloth, The F content is 0.001 to 0.1% by mass. The glass cloth according to claim 1.

3. The elastic modulus of the glass cloth is 50 to 70 GPa. The glass cloth according to claim 1 or 2.

4. The elastic modulus of the glass cloth is 50 to 63 GPa. The glass cloth according to claim 3.

5. The average diameter of the glass filaments constituting the warp and weft threads is, independently of each other, 3.5 to 5.4 μm. The glass cloth according to any one of claims 1 to 4.

6. A glass cloth according to any one of claims 1 to 5, The glass cloth is impregnated with a matrix resin, Prepreg.

7. A glass cloth comprising the glass cloth described in any one of claims 1 to 5, Printed circuit board.

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