JP2023068608A - Glass fiber and method for manufacturing the same, and glass cloth, prepreg for circuit board and printed wiring board - Google Patents

Abstract

To provide a heat-cleaned glass fiber with inherently low dielectric dissipation factor of glass.SOLUTION: The glass fiber is heat-cleaned of the sizing agent, and has a SiO2 composition of 55 mass% or more, a dielectric loss tangent at 10 GHz of 0.0016 or less, and a residual carbon content of 0.1 mass% or less from the sizing agent.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a glass fiber excellent in dielectric loss tangent, a method for producing the same, a glass cloth using the glass fiber, a substrate prepreg, and a printed wiring board.

BACKGROUND ART At present, as information terminals such as smart phones have improved performance and high-speed communication, printed wiring boards used in them have been remarkably reduced in density and ultra-thin, as well as reduced in dielectric and dielectric loss tangent. As an insulating material for this printed wiring board, a laminated board obtained by laminating prepregs obtained by impregnating glass cloth with thermosetting resin such as epoxy resin (hereinafter referred to as "matrix resin") and curing under heat and pressure. is widely used. The signal transmission loss in the substrate is described by Edward A. et al. Wolff formula: transmission loss ∝√ε×tan δ, it is known that the smaller the dielectric constant (ε) and dielectric loss tangent (tan δ) of the material, the better the improvement. It is known that the contribution of the dielectric loss tangent is large. Therefore, the glass cloth is required to have a low dielectric loss tangent, and glass cloths with improved dielectric properties such as D glass, NE glass, L glass, and Q glass have been proposed (Patent Documents 1 to 4). However, from the viewpoint of achieving sufficient transmission speed performance in future 5G communication applications, etc., there is still a need to improve these low dielectric property glass cloths that are excellent in low dielectric constant and low dielectric loss tangent.

Generally, glass cloth is coated with a sizing agent during spinning and warping of glass fiber bundles in order to prevent fluff and yarn breakage due to mechanical wear during winding and weaving. However, in the final process of manufacturing glass cloth, silane treatment is applied to increase the adhesion to the matrix resin used in the laminate. Adhesion to the glass cloth deteriorates. Therefore, the sizing agent is usually completely removed by a heat decomposition treatment, a so-called heat cleaning treatment, before the silane treatment.

If the sizing agent remains on the glass cloth after heat cleaning, the treatment with the silane coupling agent on the glass cloth will be insufficient, resulting in poor adhesion with the resin and deterioration of dielectric properties due to the remaining sizing agent. is important, but no study has been made on the influence of the heat cleaning process on the dielectric loss tangent of the glass cloth.

JP-A-5-170483 JP 2009-263569 A Japanese Unexamined Patent Application Publication No. 2009-19150 Japanese Patent Application Laid-Open No. 2006-282401

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-cleaned glass fiber having a low dielectric loss tangent inherent to glass.

A gas furnace is used in the existing heat cleaning process, and since the combustion of city gas or the like is used as a heat source, a large amount of carbon dioxide and water are produced as products. More than 50% of the glass cloth is SiO ₂ , and the Si—OH groups on the surface of the glass are highly active. Especially in a high-temperature atmosphere, it is considered that Si--OH groups are generated by taking in moisture through hydrogen bonds and breaking Si--O--Si bonds (SiO ₂ +H ₂ O→Si--OH).

The present inventors have found that the dielectric loss tangent of the glass fiber is reduced by reducing the Si--OH groups, and that there is a correlation between the Si--OH groups and the dielectric loss tangent. When the proportion of SiO ₂ in the glass composition is 55% by mass or more, it is believed that the dielectric loss tangent increases due to the cleavage of Si--O--Si bonds due to moisture in the heat cleaning process. In particular, it was found that this tendency is remarkable in glass fibers having a SiO ₂ content of 95% by mass or more. The inventors of the present invention have found such a situation and have made extensive studies. It has been found that glass fibers having a low dielectric loss tangent inherent to glass can be provided by removing the . The silane-treated glass fiber obtained by silanizing this was also a silane-treated glass fiber having a low dielectric loss tangent.

Accordingly, the present invention provides the following inventions.
1. A glass fiber having a SiO ₂ composition amount of 55% by mass or more, which is heat-cleaned from a sizing agent, having a dielectric loss tangent at 10 GHz of 0.0016 or less and a residual carbon content derived from the sizing agent of 0.1% by mass or less. glass fiber.
2. 2. The glass fiber according to 1, wherein the dielectric loss tangent of the glass fiber at 40 GHz is 0.0020 or less.
3. 2. The glass fiber according to 1, wherein the glass fiber is Q glass having a SiO ₂ composition of 95% by mass or more.
4. 2. The glass fiber according to 1, wherein the Si—OH content of the glass fiber is 10,000 ppm or less.
5. A silane-treated glass fiber obtained by silanizing the glass fiber according to 1.
6. 6. The silane-treated glass fiber according to 5, which has a volatile content of 0.5% by mass or less.
7. 7. The silane-treated glass fiber according to 6, wherein the amount of the silane coupling agent attached to the glass fiber is 0.02 to 0.5% by mass.
8. 6. The silane-treated glass fiber according to 5, wherein the dielectric loss tangent at 10 GHz after silane treatment is twice or less that before silane treatment.
9. 6. The silane-treated glass fiber according to 5, wherein the dielectric loss tangent at 40 GHz after silane treatment is twice or less that before silane treatment.
10. A printed circuit board prepreg containing the glass fiber according to any one of 1 to 9.
11. A printed wiring board using the glass fiber according to any one of 1 to 9.
12. A sizing-treated glass fiber having a SiO ₂ composition of 55% by mass or more is heated to 300 to 600° C. with an amount of water generated per unit calorific value (1,000 kcal) of 0.12 L or less. 10. A production method for producing the glass fiber according to any one of 1 to 9, comprising a step of heat cleaning with gas.
13. 13. The manufacturing method according to 12, wherein the dielectric loss tangent change ratio at 10 GHz is 0.7 to 1.3 before and after the heat cleaning step.
14. 13. The manufacturing method according to 12, wherein the dielectric loss tangent change ratio at 40 GHz is 0.7 to 1.3 before and after the heat cleaning step.

According to the present invention, it is possible to obtain a glass fiber obtained by heat-cleaning a sizing agent having a low dielectric loss tangent, and it is possible to suppress the transmission loss of substrates used in high-speed communication such as 5G, which is expected to increase in the future. effect.

The present invention will be described in detail below.
The glass fiber of the present invention is a glass fiber having a SiO ₂ composition amount of 55% by mass or more after heat cleaning of a sizing agent, a dielectric loss tangent at 10 GHz of 0.0016 or less, and a residual carbon content derived from the sizing agent. is 0.1% by mass or less. The glass fiber includes filaments, strands, chopped strands, yarns, plain weave cloths, satin cloths, flat cloths, and glass cloths such as non-woven fabrics.

The glass fiber of the present invention is obtained by coating glass with a sizing agent and then removing the sizing agent by heat cleaning. The glass before coating treatment with a sizing agent and the glass fiber subjected to heat cleaning treatment have a _SiO2 content of 55% by mass or more, preferably 95% by mass or more of Q glass, and 99.9% by mass or more of Q glass. more preferred.

The dielectric loss tangent at 10 GHz in the heat-cleaned glass fiber of the present invention, and the dielectric loss tangent at 10 GHz before silane treatment in the case of silane treatment, which will be described later, is 0.0016 or less, preferably 0.0010 or less. , 0.0008 or less. Also, the dielectric loss tangent at 40 GHz is preferably 0.0020 or less, more preferably 0.0018 or less, and even more preferably 0.0015 or less. A method for measuring the dielectric loss tangent is based on the description of Examples described later.

In the heat-cleaned glass fiber of the present invention, the carbon content of the residual carbon content derived from the sizing agent, and in the case of silane treatment, which will be described later, the carbon content before silane treatment is 0.1% by mass or less. It is preferably 0.06% by mass or less, more preferably 0.03% by mass or less, and may be 0% by mass. The method for measuring the amount of residual carbon derived from the sizing agent is based on the description of Examples described later using a carbon analyzer. Methods for reducing the residual carbon content derived from the sizing agent to 0.1% include removal of the sizing agent by washing with water and removal by heat cleaning. A cleaning method is preferred.

The Si—OH content in the heat-cleaned glass fiber of the present invention is preferably 10,000 ppm (mass) or less, more preferably 8,500 ppm or less, even more preferably 7,500 ppm or less, and may be 0 ppm. Incidentally, the method for measuring the Si—OH content in the glass fiber is based on the description of the examples described later.

[Method for producing glass fiber]
The method for producing the glass filaments is not particularly limited, but examples include a method of heating and drawing an ingot of a prescribed glass composition, and a method of forming a filament with a bushing after melting to form molten glass. In particular, when the proportion of SiO ₂ is 95% by mass or more, the melting temperature rises, making stretching with a bushing difficult, so heating and stretching with an oxyhydrogen burner is preferred.

A glass strand can be formed by applying a sizing agent to the surface of drawn glass filaments and bundling them. The sizing agent is mainly made of starch, and can be blended with a softening agent or a lubricant to impart functionality. The sizing agent composition is generally called a sizing agent. A known method can be used for the sizing agent treatment, and the type of sizing agent and the method of sizing agent treatment are not particularly limited, and a method that does not easily cause fuzz and yarn breakage is appropriately selected. The sizing treatment reduces fluff and thread breakage. Treatment methods include immersion, roller-type or belt-type applicators, spraying, and the like. A glass yarn is obtained by twisting the obtained glass strand. The twisting frequency is preferably 0.1 to 5.0 times per 25 mm.

Glass cloth is obtained by weaving glass yarns. Although the glass cloth is not particularly limited, those having a basis weight of 10 to 100 g/m ³ are preferably used. The weaving method is not particularly limited, but examples thereof include weaving methods using an air jet loom, a water jet loom, a rapier loom, a shuttle loom, and the like. When weaving with an air jet loom or the like, PVA (polyvinyl alcohol) or starch can be applied as a secondary sizing agent in order to further obtain lubricity.

[Glass fiber heat cleaning method]
As a manufacturing method for obtaining heat-cleaned glass fibers as described above, the amount of water generated per unit calorific value (1,000 kcal) is 0.12 L or less, and 300 Examples include a process of heat cleaning with a gas heated to ~600°C.

The amount of water generated per unit calorific value (1,000 kcal) is 0.12 L or less, and the specific method of heat cleaning with gas heated to 300 to 600° C. is not particularly limited. The amount of water generated per unit calorific value (1,000 kcal) is 0.12 L or less, preferably less than 0.10 L. The temperature is preferably 300-600°C, more preferably 400-600°C. Within such a range, the sizing agent can be sufficiently removed without requiring long-term heating. If the temperature exceeds 600°C, the strength may be affected. That is, by adjusting the temperature, it is possible to obtain a glass fiber having a low dielectric loss tangent inherent to glass and having excellent strength. The heat cleaning time varies depending on the heating temperature, preferably 5 to 100 hours, more preferably 12 to 72 hours, and even more preferably 30 to 72 hours. In addition, when the oxygen in the heating furnace is insufficient and the sizing agent is carbonized and blackened, oxygen may be taken in by opening and closing a damper or the like as necessary.

A device having a heating mechanism that generates 0.12 L or less of water per unit heating value (1,000 kcal) is not particularly limited as long as it has such a heating mechanism. , a muffle furnace, laser heating, and the like, which include a heating furnace having a heat generation mechanism capable of the above. In particular, since the electric furnace does not involve combustion, the amount of water in the gas can be 0.12 L or less, less than 0.1 L, less than 0.10 L, or 0 L. For example, when a gas furnace using city gas as a combustion source is used, the amount of water generated per unit calorific value (1,000 kcal) is 0.16 L.

Before and after the heat cleaning step, the dielectric loss tangent change ratio at 10 GHz and 40 GHz is preferably 0.7 to 1.3, more preferably 0.9 to 1.1. Note that the change ratio of the dielectric loss tangent at 10 GHz and 40 GHz is based on the description of Examples described later.

After the heat cleaning step, the tensile strength of the glass fiber before silane treatment is preferably 0.05 GPa or more, more preferably 0.1 GPa or more, according to the method for measuring tensile strength according to JISR 3420. Although the upper limit is not particularly limited, it may be 0.5 GPa or less.

[Silane-treated glass fiber]
The heat-cleaned glass fibers of the present invention can be silane-treated glass fibers that have been silanized. Although the silane treatment liquid is not particularly limited, an aqueous solution in which 0.05 to 1% by mass of a silane coupling agent is dispersed is suitable from the viewpoint of productivity and environmental load. Depending on the type of silane coupling agent, it can be dispersed by adjusting the pH. Although the pH adjustment method is not particularly limited, adjustment with acetic acid or ammonia is preferable according to the silane coupling agent to be used.

Silane coupling agents include trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, trimethoxysilane, triethoxysilane. silane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenylmethylvinylethoxysilane, naphthyltrimethoxysilane, naphthyltriethoxysilane, 1,4-bis(methoxydimethylsilyl)benzene, Tetramethoxysilane, tetraethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, 1,6-bis(trimethoxysilyl)hexane, vinyltrimethoxysilane, vinyltriethoxy silane, p-styryltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, Cydoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxysilane roxypropyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3 -aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-phenyl-3-aminopropyl Trimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane and its hydrochloride, N-(vinylbenzyl)-2-aminoethyl-3-aminopropylmethyldimethoxysilane and its hydrochloride salt, 3-isocyanatopropyltriethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyl Examples include alkoxysilane compounds such as dimethoxysilane and bis(trisethoxysilylpropyl)tetrasulfide, which may be used singly or in combination of two or more. Among them, 3-aminopropyltrimethoxysilane, N-(2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane and the like are preferable. Silane coupling agents are these. It is not limited to , and can be used singly or in combination of two or more.

The method of applying the silane treatment liquid is not particularly limited, but examples include a method of impregnating glass fibers in the silane treatment liquid, a treatment by roll coating, and the like. The method for drying the silane treatment liquid is not particularly limited, but includes drying methods using hot air, infrared rays, and hot rolls. The drying temperature is appropriately selected from, for example, 80 to 180° C., and preferably 90 to 150° C. in order to evaporate more moisture and react the silane coupling agent with the Si—OH groups on the surface of the glass fiber. Within this range, the silane coupling agent is dispersed on the surface of the glass fiber, and the silane coupling agent reacts favorably with the Si—OH groups on the surface of the glass fiber. If it is less than 80°C, not only does the water in the silane treatment liquid not evaporate, but the silane coupling agent and the Si—OH groups on the surface of the glass fiber do not react, resulting in deterioration of the dielectric loss tangent and outgassing when printed wiring boards are produced. As a result, water or alcohol may be generated, resulting in swelling and adversely affecting reliability. The alcohol referred to here is derived from a silane coupling agent and is mainly methanol or ethanol. If the temperature exceeds 180°C, the silane coupling agent reacts rapidly with the Si—OH groups on the surface of the glass fiber, which not only makes it impossible to uniformly silane-treat the glass fiber, but also causes the hydrocarbon of the silane coupling agent to rapidly decompose. may be oxidized to adversely affect the dielectric loss tangent.

The drying time can be appropriately changed depending on the concentration of the silane treatment liquid, but is preferably 30 seconds to 30 minutes, more preferably 1 to 10 minutes. Within this range, the water content of the silane treatment solution is removed, and the silane coupling agent reacts favorably with the Si—OH groups on the surface of the glass fiber.

The volatile content of water and alcohol in the silane-treated glass fiber is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, even more preferably 0.2% by mass or less, and particularly preferably 0.1% by mass. In order to obtain such a volatile content, the drying process after the silane treatment may be adjusted. The method for measuring the volatile content is the method described in Examples. In particular, the original dielectric loss tangent of glass with a SiO ₂ ratio of 95% by mass or more depends on the amount of Si—OH contained in the glass, but is on the order of 1.0×10 ⁻⁴ at 10 GHz. There are also those with a small amount of OH on the order of 1.0×10 ⁻⁵ . In addition, regarding glass fibers with a high SiO ₂ ratio, the dielectric loss tangent is significantly affected by the amount of Si—OH groups, and treatment with an appropriate amount of silane coupling agent in the subsequent silane treatment must be performed. , Si—OH groups, SiOMe groups, and SiOEt groups themselves due to excessive amounts of coupling agents not only adversely affect the dielectric loss tangent, but also water and alcohol produced by these functional groups affect the dielectric loss tangent and reliability of the glass fiber. found to have a great impact. In other words, by reducing the amount of water and alcohol volatiles generated when drying the glass fiber after silane treatment to 0.5% by mass or less relative to the glass fiber, the dielectric loss tangent inherent to the glass is made more effective. It has been found that silane-treated glass fibers can be provided while maintaining the

The amount of the silane coupling agent attached after the silane treatment is preferably 0.01 to 0.5% by mass, more preferably 0.02 to 0.4% by mass, relative to the glass fiber. Within such a range, when printed wiring boards are formed, the adhesiveness to the resin is better, and the reliability is further improved. If the silane coupling agent is deposited in an amount of 0.5% by mass or more, the amount of the silane coupling agent becomes excessive relative to the Si—OH on the surface of the glass fiber, and not only the dielectric loss tangent deteriorates but also the flexibility of the glass cloth is lost. Moreover, an excessive amount of silane coupling agent includes unreacted ones, which is not preferable because alcohol is generated as outgas. The adhesion amount of the silane coupling agent can be measured by ignition loss described in JISR3420.

The dielectric loss tangent (10 GHz, 40 GHz) of the silane-treated glass fiber obtained as described above is preferably 2 times or less, more preferably 1.5 times or less, and further 1.3 times or less compared to before silane treatment. preferable. In particular, the dielectric loss tangent of the Q glass fiber of 95% by mass or more obtained by heat cleaning with an apparatus having a heat generation mechanism that generates 0.12 L or less of water per unit calorific value (1,000 kcal) has a very high dielectric loss tangent. Therefore, it is easily affected by the silane treatment, and if it is within the above range, the silane treatment can be performed without deteriorating the dielectric loss tangent of the glass fiber, which originally has the dielectric loss tangent of the glass.

[Prepregs for printed circuit boards]
Since the glass fiber of the present invention has a low dielectric loss tangent, it is possible to obtain a prepreg for printed circuit boards with improved dielectric properties. The method for producing the prepreg is not particularly limited, and a general method for producing glass cloth-containing substrates, films, prepregs, and the like can be applied.

[Printed board]
Since the glass fiber of the present invention has a low dielectric loss tangent, a printed circuit board having improved dielectric properties can be obtained by using the glass fiber. It can be suitably used for electronic parts having circuits that transmit electrical signals of 10 GHz or more. A method for manufacturing a printed circuit board is not particularly limited, and a general method for manufacturing a printed circuit board can be applied.

EXAMPLES Hereinafter, the present invention will be specifically described by showing examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]
[Step 1-1]
A sizing agent for glass fibers consisting of 3.0% by mass of starch, 0.5% by mass of beef tallow, 0.1% by mass of emulsifier, and the balance of water was prepared, and a glass ingot containing 60% by mass of _SiO2 was heated and drawn. Then, a glass fiber consisting of quartz glass filaments with a diameter of 5.3 μm was produced, and after applying a glass fiber sizing agent with an applicator, it was bundled with a bundler and wound up to produce a glass strand of 200 glass filaments. . The wound glass strand was twisted at 24 T/m to produce a glass yarn.

After applying an aqueous solution consisting of 1.5% by mass of PVA (polyvinyl alcohol) and 1.5% by mass of starch as a secondary sizing agent to the obtained glass yarn, an IPC standard 1078 glass cloth was manufactured using an air jet loom. bottom. A glass cloth with a SiO ₂ content of 60% by mass to which a sizing agent is attached is used. Heat cleaning was performed by heating at 400° C. for 72 hours using an electric furnace FO-610 to obtain heat-cleaned glass fibers.

[Step 1-2]
KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: 3-methacryloxypropyltrimethoxysilane) was added to the heat-cleaned glass fiber obtained in step 1-1 so that the amount of KBM-503 attached was 0.1% by mass. A silane treatment aqueous solution containing 0.2% by mass of -503 was prepared, and the obtained glass cloth after heat cleaning was impregnated, dried at 110 ° C. for 10 minutes in a blower constant temperature thermostat DKN602 manufactured by Yamato Co., Ltd., and silane treated. A glass fiber was obtained.

[Example 2]
[Step 2-1]
A quartz glass ingot raw material containing 99.9% by mass or more of SiO ₂ was woven into glass cloth in the same manner as in step 1-1, and heated at 400° C. for 72 hours using an electric furnace FO-610 manufactured by Yamato Scientific Co., Ltd. A heat cleaning treatment was performed to obtain a heat cleaning treated glass cloth.

[Step 2-2]
The heat-cleaned glass fibers obtained in step-1 were treated in the same manner as in step 1-2 to obtain silane-treated glass fibers.

[Example 3]
[Step 3-1]
A heat-cleaned glass fiber was obtained in the same manner as in step 2-1, except that the heat-cleaning treatment was performed at 400° C. for 48 hours.

[Example 3-2]
The heat-cleaned glass fibers obtained in step 3-1 were treated in the same manner as in step 1-2 to obtain silane-treated glass fibers.

[Example 4]
[Step 4-1]
A heat-cleaned glass fiber was obtained in the same manner as in step 2-1, except that the heat-cleaning treatment was performed at 300° C. for 72 hours.

[Step 4-2]
The heat-cleaned glass fibers obtained in Example 4-1 were treated in the same manner as in step 1-2 to obtain silane-treated glass fibers.

[Example 5]
[Step 5-1]
A heat-cleaned glass fiber was obtained in the same manner as in step 2-1, except that the heat-cleaning treatment was performed at 450° C. for 72 hours.

[Example 5-2]
The heat-cleaned glass fibers obtained in step 5-1 were treated in the same manner as in step 1-2 to obtain silane-treated glass fibers.

[Example 6]
[Step 6-1]
A heat-cleaned glass fiber was obtained in the same manner as in step 2-1, except that the heat-cleaning treatment was performed at 600° C. for 72 hours.

[Example 6-2]
The heat-cleaned glass fibers obtained in step 6-1 were treated in the same manner as in step 1-2 to obtain silane-treated glass fibers.

[Example 7]
The heat-cleaned glass cloth obtained in step 2-1 was adjusted with a silane-treated aqueous solution containing 0.2% by mass of KBM-503 so that the amount of KBM-503 adhered was 0.1% by mass. After the heat cleaning, the obtained glass cloth was impregnated and dried at 110° C. for 30 seconds in a blower constant temperature thermostat DKN602 manufactured by Yamato Co., Ltd. to obtain a silane-treated glass fiber.

[Example 8]
A silane-treated aqueous solution containing 0.05% by mass of KBM-503 was adjusted so that the amount of KBM-503 adhered to the heat-cleaned glass cloth obtained in step 2-1 was 0.02% by mass, The obtained glass cloth after heat cleaning was impregnated and dried at 110° C. for 10 minutes in a blower constant temperature thermostat DKN602 manufactured by Yamato Co., Ltd. to obtain a silane-treated glass fiber.

[Example 9]
A silane-treated aqueous solution containing 1% by mass of KBM-503 was adjusted so that the amount of KBM-503 attached to the heat-cleaned glass cloth obtained in step 2-1 was 0.4% by mass. After the heat cleaning, the glass cloth was impregnated and dried at 110° C. for 10 minutes in a blower constant temperature thermostat DKN602 manufactured by Yamato Co., Ltd. to obtain a silane-treated glass fiber.

[Comparative Example 1]
A glass ingot having a sizing agent for glass fibers consisting of 3.0% by mass of starch, 0.5% by mass of beef tallow, 0.1% by mass of an emulsifier, and the balance of water, and having a _SiO2 content of 53% by mass. is heated and drawn to produce glass fibers made of quartz glass filaments with a diameter of 5.3 μm, and after applying a glass fiber sizing agent with an applicator, the fibers are bundled with a sizing machine and wound up to form a glass strand of 200 glass filaments. was made. The wound glass strand was twisted at 24 T/m to produce a glass yarn. After applying an aqueous solution containing 1.5% by mass of PVA and 1.5% by mass of starch as a secondary sizing agent to the obtained glass yarn, an IPC standard 1078 glass cloth was produced using an air jet loom. A glass cloth with a SiO ₂ content of 53% by mass to which a sizing agent is attached is used. Using an electric furnace FO-610, it was heated at 400° C. for 72 hours and heat-cleaned to obtain a heat-cleaned glass fiber.

[Comparative Example 2]
A heat-cleaned glass fiber was obtained in the same manner as in step 2-1, except that the heat-cleaning treatment was performed at 200° C. for 72 hours.
The heat-cleaned glass fibers obtained above were treated in the same manner as in step 1-2 to obtain silane-treated glass fibers.

[Comparative Example 3]
A quartz glass ingot containing 99.9% by mass or more of SiO ₂ was used as a raw material to weave glass cloth in the same manner as in step 2-1. (Gas Furnace 7m ³ Fiber Superior Kiln manufactured by Mino Ceramics Co., Ltd.), heat cleaning treatment was performed at 400° C. for 72 hours to obtain heat cleaning treated glass fibers.
The heat-cleaned glass fibers obtained above were treated in the same manner as in step 1-2 to obtain silane-treated glass fibers.

[Washing cloth (corresponding to Reference Example 1)]
The glass cloth with the sizing agent used in Example 1 before heat cleaning was washed with alkaline electrolyzed water S-2665 manufactured by Suzuki Yushi Kogyo Co., Ltd. at 60 ° C. for 2 hours to remove the adhered sizing agent, and then the glass cloth. was dried at 100° C. for 30 minutes to obtain a sizing agent-cleaned glass cloth.

[Washing cloth (corresponding to Reference Example 2)]
The glass cloth to which the sizing agent was attached before heat cleaning used in Example 2 was washed with alkaline electrolyzed water S-2665 manufactured by Suzuki Yushi Kogyo Co., Ltd. at 60 ° C. for 2 hours, and after removing the adhered sizing agent, the glass cloth. was dried at 100° C. for 30 minutes to obtain a sizing agent-cleaned glass cloth.

In the removal of the sizing agent with alkaline electrolyzed water according to Reference Examples 1 and 2 above, the Si—O—Si bond is not cleaved by heating, so the dielectric loss tangent of the glass cloth before heat cleaning can be measured. It is possible to evaluate the amount of change in dielectric loss tangent due to heat cleaning at .

The glass cloth before and after the heat cleaning treatment, the cloth before and after the silane treatment, and the washing cloth obtained above were evaluated by the following methods. The results are listed in the table below.

1. Measurement of Dielectric Loss Tangent The dielectric loss tangent of the glass cloth was measured using an SPDR (Split post dielectric resonator) dielectric resonator frequency of 10 GHz (manufactured by Keysight Technologies, Inc.) for dielectric constant measurement. The thickness of ^the glass cloth is measured using the theoretical film thickness ^.
calculated from

2. Dielectric Loss Tangent Ratio The dielectric loss tangent change before and after removal of the sizing agent was calculated based on the following formula.
Dielectric loss tangent ratio = Dielectric loss tangent of Example and Comparative example / (Dielectric loss tangent of cleaning cloth with the same amount of _SiO2 )

3. Measurement of residual carbon content derived from sizing agent 100 mg of glass fiber after heat cleaning was weighed in a porcelain crucible that had been pre-fired at 1,000°C for 2 hours, and 1.0 g of tungsten and 1.5 g of tin-coated copper were added as combustion improvers. After addition, the amount of residual carbon was measured from the amount of gas when burned at 2.2 kW using a carbon sulfur analyzer CS774 manufactured by LECO. The result of this measuring method is defined as the "residual carbon amount derived from the sizing agent".

4. Measurement of Silanol Group (Si—OH) Content The silanol content of the Q glass fiber is a value measured and calculated by the following method.
The dielectric loss tangent of the plate-like Q glass having a known silanol content was measured in the same manner as the glass cloth, and the following relational expression between the silanol content and the dielectric loss tangent was obtained.
Dielectric loss tangent (10 GHz) = 9.04 x 10 ^-8 x amount of silanol (ppm) + 5.26 x 10 ^-5
Using the obtained relational expression, the amount of silanol was calculated from the dielectric loss tangent of the glass cloth. When the residual carbon content was more than 0.1% by mass, the silanol content was calculated from the dielectric loss tangent after reducing the residual carbon content to 0.1% by mass or less with alkaline electrolyzed water.

5. Method for Measuring Volatile Content of Silane-Treated Glass Cloth The silane-treated glass cloth was dried at 150° C. for 1 hour, and the mass change was measured.
Volatile content (%) = ((silane-treated glass cloth before heating - silane-treated glass cloth after heating) / silane-treated glass cloth before heating) x 100

6. Adhesion amount of silane coupling agent Measurement was carried out according to the ignition loss method described in JISR3420.

7. Tensile Strength The glass cloth before and after the silane treatment was measured according to the tensile strength measurement method of JISR 3420 using Autograph AGS-X manufactured by Shimadzu Corporation. The results are described as strength (GPa)=(strength (N/25 mm)/25)/theoretical film thickness (μm).

8. Reliability evaluation 100 parts by mass of SLK-3000 (trade name; manufactured by Shin-Etsu Chemical Co., Ltd.) and 2 parts by mass of dicumyl peroxide (trade name: Parkmil D, manufactured by NOF Corporation) were added and put in toluene as a solvent. A resin varnish was prepared by pre-mixing with a stirrer.
The prepared resin varnish was impregnated with the silane-treated glass cloth obtained in Examples and Comparative Examples, and dried at 110° C. for 10 minutes to prepare a prepreg. At that time, the adhesion amount was adjusted to 55% by mass. After that, three sheets of the produced prepreg were laminated and cured by performing step curing at 150° C. for 1 hour and further at 180° C. for 2 hours using a vacuum decompression press. After boiling the obtained substrate for 1 hour in deionized water for 1 hour, it was immersed in a solder bath at 260°C for 30 seconds. It was judged.

As shown in Table 1, in the heat cleaning method of the present invention, the heat-cleaned glass cloth having a SiO ₂ content of 55% by mass or more has a dielectric loss tangent of 0.0016 or less at 10 GHz and 0.001 at 40 GHz. 0020 or less, which is 0.7 to 1.3 times that of the cleaning cloth. On the other hand, even if the glass cloth has a SiO ₂ content of 55% by mass or more, the dielectric loss tangent ratio is 4.6 and 2.4 at 10 GHz in Comparative Examples 2 and 3, which is insufficient as a substrate material for high-speed communication. is. In Comparative Example 2, since the sizing agent was oxidized without being burned, the dielectric loss tangent was greatly deteriorated.

Further, as a result of subjecting the heat-cleaned glass cloth obtained in Example 2 to silane treatment, the obtained silane-treated glass cloth does not deteriorate in dielectric loss tangent and is reliable when used as a substrate. could be crossed.

Claims (14)

A glass fiber having a SiO ₂ composition amount of 55% by mass or more, which is heat-cleaned from a sizing agent, having a dielectric loss tangent at 10 GHz of 0.0016 or less and a residual carbon content derived from the sizing agent of 0.1% by mass or less. glass fiber. 2. The glass fiber according to claim 1, wherein the dielectric loss tangent of said glass fiber at 40 GHz is 0.0020 or less. 2. The glass fiber according to claim 1, wherein the glass fiber is Q glass having a _SiO2 composition of 95% by mass or more. The glass fiber according to claim 1, wherein the Si-OH content of said glass fiber is 10,000 ppm or less. Silane-treated glass fiber obtained by silanizing the glass fiber according to claim 1. The silane-treated glass fiber according to claim 5, having a volatile content of 0.5% by mass or less. The silane-treated glass fiber according to claim 6, wherein the amount of the silane coupling agent attached to the glass fiber is 0.02 to 0.5% by mass. 6. The silane-treated glass fiber according to claim 5, wherein the dielectric loss tangent at 10 GHz after silane treatment is twice or less that before silane treatment. 6. The silane-treated glass fiber according to claim 5, wherein the dielectric loss tangent at 40 GHz after silane treatment is twice or less that before silane treatment. A prepreg for printed circuit boards containing the glass fiber according to any one of claims 1 to 9. A printed wiring board using the glass fiber according to any one of claims 1 to 9. A sizing-treated glass fiber having a SiO ₂ composition of 55% by mass or more is heated to 300 to 600° C. with an amount of water generated per unit calorific value (1,000 kcal) of 0.12 L or less. A manufacturing method for manufacturing the glass fiber according to any one of claims 1 to 9, comprising a step of heat cleaning with gas. 13. The manufacturing method according to claim 12, wherein the dielectric loss tangent change ratio at 10 GHz is 0.7 to 1.3 before and after the heat cleaning step. 13. The manufacturing method according to claim 12, wherein the dielectric loss tangent change ratio at 40 GHz is 0.7 to 1.3 before and after the heat cleaning step.