KR20220123425A - Low dielectric glass compositions, fibers, and articles - Google Patents

Abstract

Glass compositions and glass fibers having a low dielectric constant and low dissipation coefficient that may be suitable for use in electronic applications and articles are disclosed. The glass fibers and compositions of the present invention comprise 48.0 to 57.0 weight percent SiO ₂ ; 15.0 to 26.0 weight percent of B ₂ O ₃ ; 12.0 to 18.0 weight percent of Al ₂ O ₃ ; greater than 3.0 weight percent to 8.0 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 7.00 weight percent CaO; 5.0 weight percent or less of MgO; and 6.0 weight percent or less of TiO ₂ . In addition, the glass composition has a glass viscosity of 1000 poise at a temperature greater than 1350° C. and a liquidus temperature greater than 1100° C.

Description

Low dielectric glass compositions, fibers, and articles

This application claims the benefit of priority from U.S. Patent Application Serial No. 16/732,825, filed on January 2, 2020, and U.S. Patent Application Serial No. 16/792,658, filed February 17, 2020; This application is a national phase application of PCT/US17/67785, filed December 21, 2017, claiming priority to U.S. Patent Application No. 62/439,755, filed December 28, 2016, This is a continuation-in-part of U.S. Patent Application Serial No. 16/474,287, filed on June 27, 2019. The contents of these applications are incorporated by reference as if set forth herein in their entirety.

The present invention relates to glass compositions and fibers. More particularly, the present invention relates to glass compositions and fibers having a low dielectric constant and a low dissipation factor. In addition, the glass fibers of the present invention are preferably suitable for use in connection with electronic related devices such as reinforcement for printed circuit board laminates and the like.

Modern electronic devices typically include printed circuit boards reinforced with fiberglass. Many modern electronic devices, such as mobile or stationary cordless phones, computers, smartphones, tablets, etc., operate at high processing speeds and at high or ultra-high frequencies. have an electronic system. When glass is exposed to such high-frequency or ultra-high-frequency electromagnetic fields, the glass absorbs at least some energy and converts the absorbed energy into heat. The energy converted into heat by the glass is called dielectric loss energy. This dielectric loss energy is proportional to the "dielectric constant" and "dielectric loss tangent" of the glass composition, as shown by the following equation.

where "W" is the dielectric loss energy in the glass, "k" is a constant, "f" is the frequency, "v ² " is the potential gradient, "ε" is the dielectric constant, “tan δ” is the dielectric loss tangent. The dielectric loss tangent (tan δ) is dimensionless and is often referred to in the art by the following synonyms: “loss factor” or more generally “dissipation factor” (Df). As indicated by the above equation, the dielectric loss energy "W" increases with an increase in the dielectric constant and dielectric loss tangent (dissipation coefficient, Df) of the glass, and/or with an increase in frequency.

Two types of glass fibers commonly used to reinforce printed circuit boards are E-Glass and D-Glass. However, E-Glass has a relatively high dielectric constant in the range of about 6.1 and a relatively high dissipation coefficient in the range of about 38×10 ⁻⁴ at a frequency of about 10 GHz at room temperature. Therefore, E-Glass can produce relatively high dielectric losses, so E-Glass is a poor reinforcement material for printed circuit boards with higher electronic component densities and higher processing speeds. On the other hand, D-Glass has a relatively low dielectric constant and dissipation coefficient. However, D-Glass has a relatively high melting temperature, relatively poor workability, relatively poor mechanical performance, and relatively poor water resistance. In addition, D-Glass can inappropriately adhere to the epoxy resin, and typically contain defects in the form of streaks and bubbles. Therefore, E-Glass or D-Glass are not ideally suited for use as reinforcement fibers in high-speed printed circuit boards, neither are very suitable for circuit boards operating at high or ultra-high frequencies from about 100 MHz to about 18 GHz. Inappropriate.

Prior art attempts to provide glass formulations suitable for electronic applications include Mori's US5958808, Creux's US2004/01755557, Tamura's US6309990, Tamura's US6846761, Kuhn WO2010/011701, Yoshida US2011/0281484, Sawanoi US8679993 and Zhang CN103351102.

In an aspect of the present invention, 48.0 to 57.0 weight percent of SiO ₂ ; 15.0 weight percent B ₂ O ₃ to 26.0 weight percent B ₂ O ₃ ; 12.0 weight percent Al ₂ O ₃ to 18.0 weight percent Al ₂ O ₃ ; greater than 3.0 weight percent to 8.0 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 7.0 weight percent CaO; 5.0 weight percent or less of MgO; and, up to 6.0 weight percent TiO ₂ , wherein the composition has a glass viscosity of 1000 poise at a temperature greater than 1350° C., wherein the composition has a liquidus temperature greater than 1100° C. has

In an embodiment of the present invention, the glass composition comprises: 49.0 to 56.5 weight percent SiO ₂ ; 15.5 to 25.5 weight percent of B ₂ O ₃ ; 12.5 to 17.50 weight percent of Al ₂ O ₃ ; greater than 3.0 weight percent to 7.5 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 6.5 weight percent CaO; up to 4.5 weight percent MgO; and up to 5.5 weight percent TiO ₂ .

In an embodiment of the present invention, the glass composition comprises 50.0 to 56.0 weight percent SiO ₂ ; 16.0 to 25.0 weight percent of B ₂ O ₃ ; 13.0 to 17.0 weight percent of Al ₂ O ₃ ; greater than 3.0 weight percent to 7.0 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 6.0 weight percent CaO; up to 4.0 weight percent MgO; and up to 5.0 weight percent TiO ₂ .

In an embodiment of the present invention, the composition comprises at least 49.0 weight percent SiO ₂ ; up to 56.5 weight percent SiO ₂ ; at least 15.5 weight percent B ₂ O ₃ ; up to 25.5 weight percent B ₂ O ₃ ; up to 17.50 weight percent Al ₂ O ₃ ; up to 7.0 weight percent P ₂ O ₅ ; up to 6.5 weight percent CaO; up to 4.5 weight percent MgO; and/or up to 5.5 weight percent TiO ₂ .

In an embodiment of the present invention, the composition comprises at least 50.0 weight percent SiO ₂ ; up to 56.0 weight percent SiO ₂ ; at least 16.0 weight percent B ₂ O ₃ ; up to 25.0 weight percent B ₂ O ₃ ; up to 17.0 weight percent Al ₂ O ₃ ; up to 7.0 weight percent P ₂ O ₅ ; up to 6.0 weight percent CaO; up to 4.0 weight percent MgO; and/or up to 5.0 weight percent TiO ₂ .

In an embodiment of the invention, the composition has a liquidus temperature greater than 1100°C.

In an embodiment of the invention, the composition has a liquidus temperature greater than 1150°C.

In an embodiment of the present invention, the composition has a liquidus temperature greater than 1200°C.

In an embodiment of the invention, the composition has a glass viscosity of 1000 poise at a temperature greater than 1355°C.

In an embodiment of the invention, the composition has a glass viscosity of 1000 poise at a temperature greater than 1360°C.

In an embodiment of the present invention, the glass fibers are formed from the glass compositions described above.

In an embodiment of the present invention, the glass fiber has a dielectric constant of 6 or less and/or a dissipation coefficient of 38x10 ^-4 or less at a frequency of 10 GHz at room temperature.

In an embodiment of the present invention, the glass fiber has a dielectric constant of 4.60 or less and/or a dissipation coefficient of 30x10 ^-4 or less at a frequency of 10 GHz at room temperature.

In an embodiment of the present invention, the glass fiber has a dielectric constant of 4.55 or less and/or a dissipation coefficient of 25x10 ^-4 or less at a frequency of 10 GHz at room temperature.

In an embodiment of the present invention, the glass composition has an inherent network structure that tends to crystallize and form an Alumino-Borate Mullite crystal.

In an embodiment of the present invention, a method of providing continuously manufacturable low dielectric glass fibers is provided, the method comprising: providing any of the glass compositions described herein to a melting zone of a glass melter; heating the composition to form a temperature above the liquidus temperature; and continuously fiberizing the molten glass to produce low dielectric constant and low dissipation coefficient glass fibers.

In an aspect of the present invention, 48.0 to 57.0 weight percent of SiO ₂ ; 15.0 to 26.0 weight percent of B ₂ O ₃ ; 12.0 to 18.0 weight percent of Al ₂ O ₃ ; greater than 3.0 weight percent to 8.0 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 7.00 weight percent CaO; 5.0 weight percent or less of MgO; and a low dielectric glass fiber formed from a glass composition comprising up to 6.0 weight percent TiO ₂ , wherein the composition has a glass viscosity of 1000 poise at a temperature greater than 1350° C., wherein the glass composition has a glass composition greater than 1100° C. has a liquidus temperature.

In an embodiment of the present invention, the glass composition comprises 49.0 to 56.5 weight percent SiO ₂ ; 15.5 to 25.5 weight percent of B ₂ O ₃ ; 12.5 to 17.50 weight percent of Al ₂ O ₃ ; greater than 3.0 weight percent to 7.5 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 6.5 weight percent CaO; up to 4.5 weight percent MgO; and up to 5.5 weight percent TiO ₂ .

In an embodiment of the present invention, the glass composition comprises 50.0 to 56.0 weight percent SiO ₂ ; 16.0 to 25.0 weight percent of B ₂ O ₃ ; 13.0 to 17.0 weight percent of Al ₂ O ₃ ; greater than 3.0 weight percent to 7.0 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 6.0 weight percent CaO; up to 4.0 weight percent MgO; and up to 5.0 weight percent TiO ₂ .

In an embodiment of the present invention, the glass composition comprises no more than 49.0 weight percent SiO ₂ ; up to 56.5 weight percent SiO ₂ ; at least 15.5 weight percent B ₂ O ₃ ; up to 25.5 weight percent B ₂ O ₃ ; up to 17.50 weight percent Al ₂ O ₃ ; up to 7.0 weight percent P ₂ O ₅ ; at least 6.5 weight percent CaO; up to 4.5 weight percent MgO; and/or up to 5.5 weight percent TiO ₂ .

In an embodiment of the present invention, the glass composition comprises 50.0 weight percent or less of SiO ₂ ; up to 56.0 weight percent SiO ₂ ; at least 16.0 weight percent B ₂ O ₃ ; up to 25.0 weight percent B ₂ O ₃ ; up to 17.0 weight percent Al ₂ O ₃ ; up to 7.0 weight percent P ₂ O ₅ ; at least 6.0 weight percent CaO; up to 4.0 weight percent MgO; and/or up to 5.0 weight percent TiO ₂ .

In an embodiment of the present invention, the glass composition has a liquidus temperature greater than 1100°C.

In an embodiment of the present invention, the glass composition has a liquidus temperature greater than 1150°C.

In an embodiment of the present invention, the glass composition has a liquidus temperature greater than 1200°C.

In an embodiment of the present invention, the glass composition has a liquidus temperature greater than 1355°C.

In an embodiment of the present invention, the glass composition has a glass viscosity of 1000 poise at a temperature greater than 1360°C.

In an embodiment of the present invention, the glass fiber has a dielectric constant of 6 or less and/or a dissipation coefficient of 38x10 ^-4 or less at a frequency of 10 GHz at room temperature.

In an embodiment of the present invention, the glass fiber has a dielectric constant of 4.60 or less and/or a dissipation coefficient of 30x10 ^-4 or less at a frequency of 10 GHz at room temperature.

In an embodiment of the present invention, the glass fiber has a dielectric constant of 4.55 or less and/or a dissipation coefficient of 25x10 ^-4 or less at a frequency of 10 GHz at room temperature.

In an embodiment of the present invention, glass fibers are formed from a glass composition having an intrinsic network structure that tends to crystallize and form alumino-borate mullite crystals.

The present invention also includes a fiberglass reinforced article, such as a printed circuit board, comprising the glass fibers of the present invention. The invention also includes articles comprising fiberglass, as disclosed above, wherein the article is a printed circuit board, a woven fabric, a non-woven fabric, a unidirectional fabric, ?h chopped strand, chopped strand mat, composite material, and communication signal transport medium.

The present invention includes a method of providing continuously, manufacturable low dielectric glass fibers. The method includes providing a glass composition as disclosed herein to a melting zone of a glass melter; heating the composition to form a temperature above the liquidus temperature; and continuously fiberizing the molten glass to produce low dielectric constant and low dissipation coefficient glass fibers.

Some embodiments of the invention are described herein by way of example only, with reference to the accompanying drawings. With specific reference now in detail to the drawings, it is emphasized that the particulars shown are by way of example and not necessarily to scale and for the purpose of illustrating embodiments of the invention. In this regard, the description taken in conjunction with the drawings makes apparent to those skilled in the art how embodiments of the present invention may be practiced. From the drawing:
1 is a graph illustrating the relationship between liquidus temperature (T _liq ) and dissipation coefficient (D _f ), in accordance with some embodiments of the present invention.

The present invention relates to glass compositions and fibers which preferably have low dielectric constant values and low dissipation coefficients, also referred to herein as tan δ. The glass fibers of the present invention are preferably suitable for use in connection with electronic devices and systems operating at high throughput rates and/or high frequencies, such as mobile or stationary cordless phones, computers, smart phones, tablets, and the like. The glass fibers of the present invention preferably produce a lower dielectric constant and dissipation coefficient than that of E-Glass, but have better workability properties than that of D-Glass. Although primarily described in terms of their use in connection with the electronic devices and reinforcement of printed circuit boards, other uses and advantages of the glass compositions and glass fibers of the present invention may be considered without departing from the spirit and scope of the present invention. The present invention relates to glass fiber reinforced articles, articles comprising glass fibers, such as printed circuit boards, fabrics, nonwovens, unidirectional fabrics, hard strands, hard strand mats, composite materials, and communication signal transmission media; and methods of providing continuous and manufacturable low dielectric glass fibers.

The composition of the present invention generally comprises the following oxides, for example, silicon oxide (SiO ₂ ), boron oxide (B ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), calcium oxide (CaO), phosphorus oxide (P ₂ O ₅ ), magnesium oxide (MgO), and titanium oxide (TiO ₂ ). Additional oxides may be present as discussed below without departing from the spirit and scope of the present invention. Compositions of the present invention have, in some embodiments, a glass viscosity of 1000 poise at liquidus temperatures greater than 1100° C. and temperatures greater than 1350° C. (T log 3 ). Further, the glass fibers of the present invention preferably have a dielectric constant of 6 or less, and/or a dissipation coefficient of 38x10 ^-4 or less at a frequency of 10 GHz at room temperature. Advantageously, the composition of the present glass has the ability to fiber continuously, preferably due to the positive difference (ΔT3) between the T log 3 viscosity temperature and the liquidus temperature.

Unless otherwise stated, the following terms used in the specification and claims have the meanings provided below.

As used herein, the term "liquidus" is given its conventional and customary meaning, generally including the temperature at which equilibrium exists between the liquid glass and its main crystalline phase, (T _liq ). However, at all temperatures above the liquidus, the glass melt is free of crystals in its primary phase, and at temperatures below the liquidus, crystals can form in the melt. Thus, the liquidus temperature provides a lower temperature limit to continuously fiberize the glass.

The term “fiberization temperature” or “T log 3 viscosity temperature” is understood to mean the temperature at which the glass has a viscosity equal to 1000 poise (represented by T log 3).

As used herein, the term “delta-T”, also referred to as “ΔT ₃ ”, is given its conventional and customary meaning in the art, generally including the difference between the fiberization temperature and liquidus, and thus the fiberization of glass compositions. is a characteristic The greater the delta-T, the more process flexibility there is during the formation of the glass fibers and the less likely it is that devitrification of the glass melt will occur during melting and fibrillation. Typically, the greater the delta-T, the lower the cost of producing glass fibers, in part by extending bushing life and providing a wider fiber-forming process window.

The term “fiber” refers to an elongated body whose length dimension exceeds the transverse dimensions of width and thickness. Accordingly, the term fiber refers to monofilament, multifilament, ribbon, strip, staple and other types of chopped, cut or discontinuous having regular or irregular cross-sections. other forms such as fibers. Fiber and filament are used interchangeably herein.

The term "E-Glass" is used according to its meaning as described in ASTM D-578.

The term “D-Glass” refers to a glass composition having properties as indicated herein.

"Low dielectric constant" means a glass fiber having a lower dielectric constant than E-Glass. As an example, E-Glass has a dielectric constant of about 6.1 at a frequency of 10 GHz at room temperature.

"Low dissipation coefficient" means a glass fiber having a lower dissipation coefficient than E-Glass. As an example, E-Glass has a dissipation coefficient of about 38x10 ^-4 at a frequency of 10 GHz at room temperature.

"Low dielectric glass fiber" means a glass fiber of low dielectric constant and low dissipation coefficient as defined herein.

In general, glass molten at sufficiently high temperatures and for sufficiently long periods of time tends to be chemically and structurally homogeneous, with defects in regions of different chemical makeup or atomic arrangement. Moreover, the minimum amount of homogeneity required for continuous fiberization is a molten state in which the inhomogeneity is so small that it does not disturb the fiberization process so that the fibers can be stably and continuously formed. Efficient fiberization requires consistent glass melt quality with respect to the viscosity of the liquid. Perturbation in viscosity disrupts flow and causes fiber breakage during formation. Glass melts are defective from unmelted batch materials (stone, poorly melted or homogenized glass (stripes/cords)) and devitrification products (crystals formed at temperatures below T _liq ) are typical causes. During the course of its research, the inventors discovered that the glasses in the instant glass family are susceptible to liquid-liquid immiscibility (glass phase separation) upon cooling from high temperature.Phase separation is a process in which a homogeneous liquid at high temperature forms two different glasses upon cooling. tend to separate thermodynamically, and often have very different compositions, liquid structures, and related properties.Moreover, phase-separated glasses can exhibit discontinuities rather than continuous viscosity behavior as a function of temperature, so the phase-separated regions of the melt are It may interfere with the formation of stable fibers.

In an attempt to understand and control this phase separation tendency, we utilized the following method to characterize the glass melt stability of each composition after melting and during cooling. At the end of each melt-cycle, the crucible was removed from the furnace and allowed to cool naturally below the glass transition temperature, Tg. Unstable glass exhibited varying degrees of opalescence (light scattering) when cooled. Each melt is rated on a scale of 1 to 6 (“melt instability index”), from no milky (1, very stable) to 6 (least stable, opaque). This rating was sufficient to help distinguish areas of good glass forming stability from areas of poor or unstable glass forming behavior. Glasses with high melt instability index values (greater than 4) can be predicted to be difficult to fiber in a continuous/stable fabrication process. References to these melt instability index values will be made throughout this specification, including the table of laboratory results included below.

A glass composition is provided for forming glass fibers which are preferably suitable for use in electronic applications and articles and which can preferably be economically formed into glass fibers through continuous fiberization.

In some embodiments of the present invention, the glass fibers comprise a composition having 45 to 58 weight percent silicon dioxide (SiO ₂ ) (also referred to herein as silica). Alternatively, the silicon dioxide may be present at 45.5 to 57.5 weight percent. Also alternatively, the silicon dioxide content may be from 46 to 57 weight percent. In still a further embodiment, the silicon dioxide content may be less than 56.75 weight percent. In still even further embodiments, the silicon dioxide content may be less than 56.50 weight percent. When the silicon dioxide percentage is outside this range, the viscosity and fiberization of the glass are typically affected. For example, the viscosity of the glass can be reduced to the extent of devitrification (crystallization) during fiberization results when the silicon dioxide is less than 45 weight percent of the total composition of the glass fibers. In contrast, when silicon dioxide is greater than 58 weight percent of the total composition of the glass fibers, the glass can become too viscous, making it more difficult to melt, homogenize, and refine it. Accordingly, the silica content is preferably 45 to 58 weight percent of the total composition of the glass composition. In addition, when combined with the other components specified herein, a silica content of 45.00 to 58.00 weight percent typically results in glass fibers having a low dissipation coefficient as well as a desirable low dielectric constant. In one embodiment of the glass fibers and/or glass compositions of the present invention, the silica content is at least 45.50 weight percent. Alternatively, the silica content is at least 46.00 weight percent. In another embodiment of the glass fibers and/or glass compositions of the present invention, the silica content is no more than 57.50 weight percent. Alternatively, the silica content is 57.00 weight percent or less. Still further alternatively, the silica content is no more than 56.75 weight percent. In another embodiment, the silica content is no more than 56.50 weight percent.

Notwithstanding the above, the inventors have identified certain surprisingly useful and/or effective formulations wherein the glass fibers comprise a composition having from 48 to 57 weight percent silicon dioxide (SiO ₂ ). Alternatively, the silicon dioxide content may be from 49 to 56.5 weight percent. Still alternatively, the silicon dioxide content may be from 50 to 56 weight percent. In still a further embodiment, the silicon dioxide content may be less than 56.0 weight percent. When the silicon dioxide percentage is outside this range, the viscosity and fibrillation of the glass are typically affected. For example, the viscosity of the glass can be reduced to the extent of devitrification (crystallization) during fiberization results when the silicon dioxide is less than 48 weight percent of the total composition of the glass fibers. In contrast, when silicon dioxide is greater than 57 weight percent of the total composition of the glass fibers, the glass becomes too viscous, making it more difficult to melt, homogenize, and purify. Accordingly, the silica content is preferably 48 to 57 weight percent of the total composition of the glass. It should also be understood that SiO ₂ controls the stability of the formulation and the weight percentage of SiO ₂ is arbitrarily selected for this consideration along with other factors described herein.

In some embodiments of the invention the glass fibers comprise greater than 18 weight percent boron oxide (B ₂ O ₃ ) and up to 26 weight percent boron oxide. Alternatively, the boron oxide content may be between 18.5 and 25 weight percent. Also alternatively, the boron oxide content may be between 19 and 22 weight percent. A high percentage of boron oxide, eg, greater than 26 weight percent, can lead to excessive loss of B ₂ O ₃ during melting, poor homogeneity, low strength, and poor mechanical properties. When combined with the other components as shown herein, boron oxide contents greater than 18.00 weight percent and up to 26.00 weight percent typically produce glass fibers having a desired low dielectric constant as well as a low dissipation coefficient. In one embodiment of the glass fibers and/or glass compositions of the present invention, the boron oxide content is at least 18.50 weight percent. Alternatively, the boron oxide content is at least 19.00 weight percent. In another embodiment of the glass fibers and/or glass compositions of the present invention, the boron oxide content is 25.00 weight percent or less. Alternatively, the boron oxide content is 24.00 weight percent or less.

Notwithstanding the above, the inventors have identified certain surprisingly useful and/or effective formulations wherein the glass fibers comprise a composition having 15 weight percent boron oxide (B ₂ O ₃ ) and 26 weight percent boron oxide. . In general, B ₂ O ₃ is advantageous for lowering Df, but if it is too large, it may create glass instability in the form of phase separation. Alternatively, the boron oxide content may be between 15.5 and 25.5 weight percent. Further alternatively, the boron oxide content may be between 16 and 25 weight percent. A high percentage of boron oxide, eg, greater than 26 weight percent, can lead to excessive loss of B ₂ O ₃ during melting, poor homogeneity, poor mechanical properties, and glass instability in the form of phase separation. Also, a low percentage of boron oxide, eg, less than 15 weight percent, may lead to insufficient dielectric properties. Accordingly, the boron oxide content is preferably between 15 weight percent and 26 weight percent of the total composition of the glass. Also, when combined with other components as shown herein, boron oxide content of 15.00 to 26.00 weight percent produces glass fibers with a desired low dielectric constant as well as a low dissipation coefficient. In one embodiment of the glass fibers and/or glass compositions of the present invention, the boron oxide content is at least 16.0 weight percent. Also, alternatively and/or optionally, the boron oxide content is not more than 20.00 weight percent. In one embodiment of the glass fibers and/or glass compositions of the present invention, the boron oxide content is less than or equal to 25.00 weight percent.

In some embodiments of the invention the glass fibers comprise a composition having greater than 16 weight percent and up to 23 weight percent aluminum oxide. Alternatively, the aluminum oxide content may be greater than 16 weight percent and up to 22.5 weight percent. Also alternatively, the aluminum oxide content may be greater than 16 weight percent and up to 22 weight percent. The percentage of aluminum oxide relative to the total composition of glass fibers can affect the viscosity and fiberization process. For example, high percentages of aluminum oxide, eg, greater than 23 weight percent, can reduce melt viscosity and produce devitrification during fiberization. Low percentages of aluminum oxide, eg, 18 weight percent or less, can lead to phase separation and poor fiber formation. Accordingly, the alumina content is preferably greater than 16 weight percent and up to 23 weight percent of the total composition of the glass. Also, when combined with other components as shown herein, an alumina content of 16.00 to 23.00 weight percent typically results in glass fibers having a desired low dielectric constant as well as a low dissipation coefficient. In one embodiment of the glass fibers and/or glass compositions of the present invention, the alumina content is no more than 22.50 weight percent. Alternatively, the alumina content is 22.00 weight percent or less.

Aluminum oxide is known to stabilize glasses that undergo phase separation/melt instability. However, since it is also known to increase devitrifiction/crystallization propensity at high levels, it may not be good for the fiber to build stability with respect to delta-T. Aspects of this tendency of Al ₂ O ₃ , for example, in some embodiments as opposed to B ₂ O ₃ , and in the other components of the formulations described, it is important to find the correct balance among all of them. Notwithstanding the foregoing and the scope previously disclosed herein, the inventors have identified certain surprisingly useful and/or effective formulations, wherein, in some embodiments of the invention, the balance of Df behavior and T _liq behavior is This is achieved when Al ₂ O ₃ is present at 12 to 18 weight percent. In some embodiments of the present invention, Al ₂ O ₃ is present at 12.5 to 17.5 weight percent. In some embodiments of the present invention, Al ₂ O ₃ is present at 13 to 17 weight percent. It is to be understood that these ranges are provided to aid the reader in envisioning a working formulation for the inventor's composition, but also using any weight percentages including within any ranges of Al ₂ O ₃ described herein. It should be understood that formulations can be used to achieve formulations acceptable for the described purposes of the present invention.

Glass fibers of the present invention typically also include compositions having greater than 3 weight percent to 8 weight percent phosphorus oxide (P ₂ O ₅ , also referred to as phosphorus pentoxide). Alternatively, the phosphorus oxide content may be greater than 3 weight percent to 7.5 weight percent. Also alternatively, the phosphorus oxide content may be greater than 3 weight percent to 7 weight percent. The inventors have surprisingly found that this range is optimal for balancing the Df behavior with T _liq and the melt instability index. More specifically, P ₂ O ₅ can be synergistically related to the Al ₂ O ₃ content of the glass, thereby reducing the melt stability (instability index value) but at the same time also improving the key metrics of Df and T _liq . It turned out The inventors speculate that phosphorus preferentially associates with a portion of the Al ₂ O ₃ forming the AlPO ₄ network link so that the portion of the Al ₂ O ₃ cannot be devitrified into the alumino-borate mullite. It should also be noted that the inventors have identified this at P ₂ O ₅ in the range of greater than 3% to 7% weight percent, although it may have a negative impact on viscosity in terms of what is known to those skilled in the art.

All of the alkaline earth oxides (magnesium oxide (MgO), calcium oxide (CaO), and sometimes strontium oxide (SrO)) allow these glasses to melt and homogenize at reasonable temperatures achievable by melting furnaces known in the art. help However, these oxides directly affect and harm the low dielectric behavior required by industry (MgO increases Df less than CaO, SrO increases Df more than CaO). CaO is typically the preferred alkaline earth metal addition as it typically provides the best compromise between viscosity, T _liq and Df compared to alternatives. However, too little alkaline earth metal oxide drives the glass melt towards instability (higher index number). For at least this reason, the glass fiber compositions of the present invention may comprise CaO (also referred to herein as calcia) and/or MgO, as described below.

The glass fibers of the present invention, in some embodiments of the present invention, comprise a composition having greater than 0.25 weight percent calcium oxide to 7.0 weight percent calcium oxide. Alternatively, the calcium oxide content may be greater than 0.25 weight percent to 6.5 weight percent. Also alternatively, the calcium oxide content may be greater than 0.25 weight percent to 6 weight percent. Still and alternatively, the calcium oxide content may be greater than 2.5 weight percent to 5.0 weight percent. The weight percentage of calcium oxide can affect the viscosity of the glass fiber and the devitrification process. A high percentage of calcium oxide, eg, greater than 7.0 weight percent, may result in insufficient dielectric properties. Also, low percentages of calcium oxide, for example less than 0.25 weight percent, can lead to poor fiber formation. For example, at calcia below 0.25 weight percent, the viscosity is too high and the glass homogeneity obtained is insufficient for acceptable fiber formation. When combined with other components as shown herein, in some embodiments, a calcium oxide content of 1.25 weight percent to 5.85 weight percent typically produces glass fibers having a desired low dielectric constant as well as a low dissipation coefficient. In one embodiment of the glass fibers and/or glass compositions of the present invention, the calcia content is 4.5 weight percent or less. Alternatively, the calcia content is less than or equal to 4.25 weight percent. Also alternatively, the calcia content is less than or equal to 4.00 weight percent.

The glass fiber compositions of the present invention may also include MgO (also referred to herein as magnesia). The glass fibers of the present invention may comprise a composition having up to 5.0 weight percent magnesium oxide. Alternatively, the magnesium oxide content is 4.5 weight percent or less. Also alternatively, the magnesium oxide content may be up to 4.0 weight percent. In still a further alternative embodiment, the magnesium oxide content may be up to 2.0 weight percent. In a still further alternative embodiment, the magnesium oxide content is less than or equal to 1.5 weight percent. As with calcium oxide, the weight percentage of magnesium oxide can be detrimental to the viscosity and devitrification process of the glass fiber. Also, high percentages of magnesium oxide, eg, greater than 5.0 weight percent, can lead to insufficient dielectric properties.

Titanium oxide (TiO ₂ ) is optionally present or intentionally introduced in the glass compositions and fibers of the present invention. In one embodiment, the weight percent of titanium oxide is 6.0 or less. Alternatively, the weight percent of titanium oxide is 5.5 or less. Also alternatively, the weight percent of titanium oxide is 5.0 or less. Flavoring at least 6 weight percent titanium oxide is believed to increase the propensity for phase separation in glass compositions and fibers, especially when combined with phosphorus pentoxide. Titanium oxide typically acts as a viscosity reducing agent and may be intentionally added or present as an impurity from common raw materials. Thus, titanium oxide is present in the glass composition in a weight percent of 0.01 or greater. Alternatively, the titanium oxide may be present in the glass composition at a weight percent greater than or equal to 0.05. Also alternatively, titanium oxide may be present in the glass composition at a weight percent of 0.1 or greater.

The stated purpose of the present invention is to produce the most stable glass reasonably possible for the melting and fiberizing process, so that up to 6 weight percent TiO ₂ within this series is not detrimental to the T _liq and such glass does not become fibrillated. It was not predicted by one of ordinary skill in the art that this could be tolerated without producing a delta-T behavior (delta-T < 40° C.). See page 37, Wolfram Holand, et al., Glass Ceramic Technology, 2nd Edition, Wiley and Sons, July 2012.

TiO ₂ is known in the art as an acceptable additive to other low Dk glasses to lower its viscosity. Using this point of view, the inventors have found that by incorporating any amount of a nucleating agent (TiO ₂ , which can be predicted to increase the rate of crystallization, and possibly an increase in T _liq ), the acceptable-T in the base glass composition It was counter-intuitive to be able to achieve a range (T log 3 -T _liq ), but it is also known to reduce viscosity (T log 3 ).

Interestingly, none of the related prior art shows any examples of significant amounts of P ₂ O ₅ and TiO ₂ combined together, making it difficult to predict any synergistic or desirable behavior.

Additional oxides may be present in the glass fibers and compositions of the present invention without departing from the scope of the present invention. For example, oxides such as lithium oxide (Li ₂ O), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), barium oxide (BaO), strontium oxide (SrO), zinc oxide (ZnO) ), fluorine (F or F ₂ ), tin oxide (SnO ₂ ), zirconium oxide (ZrO ₂ ), chromium oxide ((Cr ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ) , manganese oxide (Mn ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), and/or vanadium oxide (V ₂ O ₃ ) Moreover, the combined total amount of these additional oxides means that they As long as it does not change the function, the total composition is less than 3 weight percent.Alternatively, the combined total amount of these additional oxides can be less than 2 weight percent of the total composition.Also, alternatively, the combination of these additional oxides is less than or equal to 2 weight percent. The total amount can be less than 1.5 weight percent of the total composition Still also alternatively, the combined total amount of these additional oxides can be 3.0, 2.0 and/or 1.0 weight percent or less of the total composition in some embodiments of the present invention. have.

Due to the significant effect that small amounts of alkali metal oxides can have on the glass composition, the combined total amount of alkali metal oxides such as Na ₂ O, K ₂ O, and Li ₂ O is less than or equal to 1.0 weight percent of the total of the composition. . More preferably, the combined total amount is less than or equal to 0.5 weight percent of the total of the composition. Even more preferably, the combined total amount is less than or equal to 0.25 weight percent of the total of the composition.

Examples of glass compositions and glass fibers of the present invention are shown herein. In one embodiment, the glass composition and/or glass fibers comprise from 48.0 to 57.0 weight percent SiO ₂ ; 15.0 to 26.0 weight percent of B ₂ O ₃ ; 12.0 to 18.0 weight percent of Al ₂ O ₃ ; greater than 3.0 weight percent to 8.0 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 7.0 weight percent CaO; 5.0 weight percent or less of MgO; and up to 6.0 weight percent TiO ₂ . Alternative glass compositions and/or glass fibers of the present invention comprise 49 to 56.5 weight percent of SiO ₂ ; 15.5 to 25.5 weight percent of B ₂ O ₃ ; 12.5 to 17.5 weight percent Al ₂ O ₃ ; greater than 3.0 to 7.5 weight percent of P ₂ O ₅ ; greater than 0.25 weight percent to 6.5 weight percent CaO; up to 4.50 weight percent MgO; and up to 5.5 weight percent TiO ₂ . In still further alternative glass compositions and/or glass fibers of the present invention, the following components may be included: from 50 to 56.0 weight percent of SiO ₂ ; 16.0 to 25.0 weight percent of B ₂ O ₃ ; 13.0 to 17.0 weight percent of Al ₂ O ₃ ; greater than 3.0 weight percent to 7.0 weight percent P ₂ O ₅ ; greater than 0.25 weight percent to 6.0 weight percent CaO; up to 4.0 weight percent MgO; and 5.0 weight percent or less of TiO ₂ .

The glass composition of the present invention has a liquidus temperature greater than 1100°C. In alternative embodiments, the glass composition may have a liquidus temperature greater than 1150°C. In still further alternative embodiments, the glass composition may have a liquidus temperature greater than 1200°C. Having a liquidus temperature above 1100°C, or more preferably above 1150°C, may be preferred for fiberizing the glass composition according to the present invention.

In addition, the glass compositions of the present invention may have a T log 3 viscosity temperature greater than 1350°C. Alternatively, the glass composition may have a T log 3 viscosity temperature greater than 1355°C. In still a further alternative embodiment, the glass composition may have a T log 3 viscosity temperature greater than 1360°C. Having a T log 3 viscosity temperature greater than 1350° C. may be preferred for fiberizing a glass composition according to the present invention.

The glass fibers of the present invention may have a dielectric constant of 6 or less. Alternatively, the glass fibers may have a dielectric constant of 4.60 or less. In a further alternative embodiment, the glass fiber may have a dielectric constant of 4.55 or less.

In addition, the glass fibers of the present invention may have a dissipation coefficient of 38x10 ^-4 or less at a frequency of 10 GHz at room temperature. Alternatively, the glass fiber may have a dissipation coefficient of 30x10 ^-4 or less at a frequency of 10 GHz at room temperature. In a further alternative embodiment, the glass fiber may have a dissipation coefficient of 25×10 ⁻⁴ or less at a frequency of 10 GHz at room temperature.

The glass fibers of the present invention can be incorporated into glass fiber-reinforced articles, such as printed circuit boards. The glass fibers of the present invention may also be used in connection with articles such as wovens, nonwovens, unidirectional fabrics, hard strands, hard strand mats, composite materials, and communication signal transmission media.

The present invention also includes methods of providing continuous, manufacturable low dielectric glass fibers. The method includes providing a glass composition as disclosed herein to a melting zone of a glass melter; heating the composition to form a temperature above the liquidus temperature; and continuously fiberizing the molten glass to produce low dielectric constant and low dissipation coefficient glass fibers.

As discussed above, the composition of glass for providing low dielectric constant glass fibers comprises, at least in part, the weight percentages of the oxides discussed above, as well as silicon dioxide, aluminum oxide, boron oxide, calcium oxide, magnesium oxide, phosphorus oxide, and /or based on the combined weight of titanium oxide. In one aspect, in addition to the other parameters discussed herein, such as viscosity temperature, the combination of these parameters makes it possible to obtain glass fibers having a low dielectric constant and a low dissipation coefficient as shown herein. .

Compared to previous efforts in the art, Creux's formulation shows a glass with overall poor Df behavior (Df ~ 0.0090 at 10 GHz) as shown in the two examples of US2004/01755557. In contrast, the present invention achieves Df < 0.0028. Also, Kreux T log 3 is < 1350 °C and T _liq is < 1000 °C.

On the other hand, Zhang does not describe the Df behavior of its glass at all. T log 3 of window glass is < 1350 °C and T _liq are all < 1000 °C. Interestingly, Chang describes that its glass has excellent devitrification behavior as both the primary crystalline phases (Wollastonite/Diopside/Calcium Feldspar) compete with each other. Note: Paragraph [0014] of CN103351102.

Most, if not all, of the prior art mentioned above to achieve the presently described glasses of the present invention, as the glass family in the art has a T _liq of less than 1000° C. as well as a T log 3 viscosity temperature of less than 1350° C. It is clear that they did not combine

It is well known in the art that chemical composition is a major determinant of the primary crystal phase to be devitrified from the glass melt. See page 4 of Holand.

It is well known in the art that TiO ₂ is used by glassmakers as a nucleating agent to promote crystallization and help devitrify the glass. See page 37 of Holand. However, none of the prior art, including Mori's US5958808, Tamura's US6309990, Tamura's US6846761, and Yoshida's US2011/0281484, are disclosed by the present inventors. has not demonstrated or demonstrated effective use of TiO ₂ with substantial/or significant amounts of P ₂ O ₅ , believed to produce a synergistic effect when combined in the amounts described herein.

In addition, the inventors have unexpectedly discovered that the measured dielectric loss of the present invention appears to be closely related to the crystallization behavior of instant glasses. That is, glasses with high T _liq values tend to have better, ie, lower, Df properties. Figure 1 shows that these data relationships are derived from the advantages of the present invention.

In order to achieve the desired Df behavior (Df < 0.0028, or < 0.0027, or < 0.0026, even lower), the glass as defined by the formulation disclosed by the inventors of the present application will tend to devitrify more readily. ie, at higher T _liq values, for example, it is clear that the value is > 1100 °C. Also, the most preferred Dfs is at T _liq well above 1100°C.

The inventors have also surprisingly found that the most desirable glasses for obtaining low Df behavior are those with a unique network structure that tends to crystallize and form alumino-borate mullite (saliva) crystals.

On the other hand, Chang clearly states that his glass produces wollastonite, diapyroxene and Ca-feldspar crystals rather than alumino-borate mullite.

We speculate that glasses that tend to belong to the alumino-borate mullite primary phase field have network structures that are inherently suitable for both good glass formation and excellent (ie, low) Df behavior.

Similar to Creux, the glass invented by Kuhn (WO2010/011701) also has an inferior Df behavior (Df ≥ 0.0044) and Example 1 of 6 is effective for acceptable fiber formation. represents the positive delta-T for (see: Kuhn, Table II).

Although the inventors' unexpectedly effective formulations, along with their findings, have been generally described herein, a further understanding is provided for purposes of explanation only and is not intended to be exhaustive or limiting at all, unless otherwise indicated. It can be obtained by specific examples.

Example

Examples of glass compositions prepared in accordance with the present invention are shown below. The specific ingredients and amounts thereof recited in these examples, as well as other conditions and details, should not be considered as unduly limiting of the invention. Throughout these examples and this description, all percentages, ratios, and ratios are in units of weight (mass), unless otherwise indicated.

Exemplary glass compositions of the present invention are shown in Tables 1-12 below. The liquidus temperature of an example of a glass composition is denoted as “T _liq ” and when the glass composition has a viscosity of 1000 poise, the temperature denotes “T3” (also referred to as “T log 3” viscosity temperature). The liquidus temperature and T3 temperature of the example glass compositions were measured for some of the glass compositions and calculated for others. Glass fibers were formed using the example compositions and dielectric constant and dissipation coefficient were measured for some of the glass fibers and calculated for others. The dielectric constant is indicated by the "Dk" value and the dissipation coefficient is indicated by the "Df" value.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[Table 7]

[Table 8]

[Table 9]

[Table 10]

[Table 11]

[Table 12]

Batches with the sample glass compositions shown in Tables 1-12 were prepared as described below. Glass synthesis included batch pre-treatment (mechanical and thermal), primary melting, fritting or crushing in water, secondary melting, and finally pouring the glass into a graphite mold.

Glass specimens were tested for crystallization potential (liquidus temperature) according to ASTM C 829-81.

T log 3 viscosity temperature was measured using ASTM C 965-81.

Measurements of dielectric properties at 10 GHz were performed using a split post dielectric resonance technique, also referred to in the art as the SPDR test.

As shown in Tables 1-12, at 10 GHz, the glass compositions of the Examples have a dielectric constant of less than 4.56, and a dissipation coefficient of 25x10 ^-4 or less. Specifically, at 10 GHz, the dielectric constant is 4.22 to 4.56, and the dissipation coefficient is 18x10 ^-4 to 25x10 ^-4 . Accordingly, the glass composition in the Examples exhibited a low dielectric constant and a low dissipation coefficient below that of E-Glass.

In addition, the glass compositions of the Examples exhibited a T log 3 viscosity temperature of 1374° C. to 1447° C., which is similar to the typical viscosity temperature of D-Glass (approximately 1400° C.). Having a T log 3 viscosity temperature greater than 1350° C. is advantageous for fiberizing the glass composition according to the invention. Thus, according to an embodiment, and according to an embodiment of the present invention, the glass composition exceeds 1350°C.

In addition, the glass compositions of Examples exhibited a liquidus temperature of 1136°C to 1374°C. Having a liquidus temperature greater than 1100° C., or in some embodiments greater than 1150° C., is advantageous for fiberizing a glass composition according to the present invention. Thus, according to an embodiment, and according to an embodiment of the present invention, the glass composition exceeds 1100°C.

The glass fibers of the present invention have a low dielectric constant and a low dissipation coefficient and are excellent as glass fibers for printed wiring boards. Fiberglass is very particularly suitable for reinforcing printed wiring boards for high-density circuits used in high speed routing systems. In addition, the glass composition used to make the fibers of the present invention has excellent workability. Therefore, it is possible to easily produce stable, low dielectric glass fibers.

A variety of base materials containing the glass fibers of the present invention can be prepared including wovens, nonwovens, unidirectional fabrics, knitted products, ?hed strands, rovings, filament wound products, glass powders, and mats. However, the present invention is not limited thereto. A composite material formed of at least one of such a base material and a plastic resin matrix (eg, thermoplastic, bonded thermoplastic, sheet molding compound, bulk molding compound, or prepeg). They can also be used as reinforcement for peripheral communication devices and the like. For example, composite materials comprising glass fibers according to the present invention may be used in radar transparency applications at frequencies ranging from about 300 MHz to about 30 GHz.

The disclosed and described process relates to glass fibers by mechanically damping a stream of molten glass flowing from an orifice located at the base of a fiberizing bushing, powered by heat-resistant or other means. can be obtained. These glass fibers may be particularly intended for the production of meshes and fabrics used in composites with organic and/or inorganic matrices.

If desired, detailed embodiments of the present invention are disclosed herein; It should be understood that the disclosed embodiments are merely illustrative of the invention, which may be embodied in various alternative forms. Accordingly, specific structural and functional details disclosed herein should not be construed as limiting, but merely as a basis for the claims and as a representative basis for teaching those skilled in the art to variously employ the present invention. It will be apparent to those skilled in the art that many modifications and substitutions can be made to the foregoing description of preferred embodiments and embodiments without departing from the spirit and scope of the invention as defined by the appended claims.

While various embodiments and embodiments of the invention have been described as above, this description has been presented for purposes of illustration and description. Variations, changes, modifications, and departures from the disclosed embodiments, systems, and methods may be employed without departing from the spirit and scope of the present invention.

Claims (19)

48.0 to 57.0 weight percent SiO ₂ ;
15.0 to 26.0 weight percent of B ₂ O ₃ ;
12.0 to 18.0 weight percent of Al ₂ O ₃ ;
greater than 3.0 weight percent to 8.0 weight percent P ₂ O ₅ ;
greater than 0.25 weight percent to 7.0 weight percent CaO;
5.0 weight percent or less of MgO; and,
less than 6.0 weight percent TiO ₂
A glass composition comprising:
the composition has a glass viscosity of 1000 poise at a temperature greater than 1350° C.;
wherein the composition has a liquidus temperature greater than 1100°C. According to claim 1,
The glass composition comprises:
49.0 to 56.5 weight percent SiO ₂ ;
15.5 to 25.5 weight percent of B ₂ O ₃ ;
12.5 to 17.5 weight percent Al ₂ O ₃ ;
greater than 3.0 weight percent to 7.5 weight percent P ₂ O ₅ ;
greater than 0.25 weight percent to 6.5 weight percent CaO;
up to 4.5 weight percent MgO; and,
less than 5.5 weight percent TiO ₂
A glass composition further comprising a. According to claim 1,
The glass composition comprises:
50.0 to 56.0 weight percent SiO ₂ ;
16.0 to 25.0 weight percent of B ₂ O ₃ ;
13.0 to 17.0 weight percent of Al ₂ O ₃ ;
greater than 3.0 weight percent to 7.0 weight percent P ₂ O ₅ ;
greater than 0.25 weight percent to 6.0 weight percent CaO;
up to 4.0 weight percent MgO; and,
less than 5.0 weight percent TiO ₂
A glass composition further comprising a. According to claim 1,
the composition
at least 49.0 weight percent SiO ₂ ;
up to 56.5 weight percent SiO ₂ ;
at least 15.5 weight percent B ₂ O ₃ ;
up to 25.5 weight percent B ₂ O ₃ ;
up to 17.50 weight percent Al ₂ O ₃ ;
up to 7.0 weight percent P ₂ O ₅ ;
up to 6.5 weight percent CaO;
up to 4.5 weight percent MgO; and/or;
5.5 weight percent or less of one or more of TiO ₂
A glass composition further comprising a. According to claim 1,
the composition
at least 50.0 weight percent SiO ₂ ;
up to 56.0 weight percent SiO ₂ ;
at least 16.0 weight percent B ₂ O ₃ ;
up to 25.0 weight percent B ₂ O ₃ ;
up to 17.0 weight percent Al ₂ O ₃ ;
up to 7.0 weight percent P ₂ O ₅ ;
up to 6.0 weight percent CaO;
up to 4.0 weight percent MgO; and/or;
5.0 weight percent or less of one or more of TiO ₂
A glass composition further comprising a. According to claim 1,
wherein the glass composition has an inherent network structure that crystallizes into and tends to form Alumino-Borate Mullite crystals. A method of providing a continuously manufacturable low dielectric glass fiber comprising:
providing the glass composition according to claim 1 to a melting zone of a glass melter;
heating the composition to form a temperature above the liquidus temperature; and
continuously fiberizing the molten glass to produce low dielectric constant and low dissipation coefficient glass fibers;
A method comprising 48.0 to 57.0 weight percent SiO ₂ ;
15.0 to 26.0 weight percent of B ₂ O ₃ ;
12.0 to 18.0 weight percent of Al ₂ O ₃ ;
greater than 3.0 weight percent to 8.0 weight percent P ₂ O ₅ ;
greater than 0.25 weight percent to 7.00 weight percent CaO;
5.0 weight percent or less of MgO; and
less than 6.0 weight percent TiO ₂
A low dielectric glass fiber formed from a glass composition comprising:
the composition has a glass viscosity of 1000 poise at a temperature greater than 1350° C.;
wherein the glass composition has a liquidus temperature greater than 1100°C;
Low dielectric fiberglass. 9. The method of claim 8,
The glass composition comprises:
49.0 to 56.5 weight percent SiO ₂ ;
15.5 to 25.5 weight percent of B ₂ O ₃ ;
12.5 to 17.50 weight percent of Al ₂ O ₃ ;
greater than 3.0 weight percent to 7.5 weight percent P ₂ O ₅ ;
greater than 0.25 weight percent to 6.5 weight percent CaO;
up to 4.5 weight percent MgO; and
less than 5.5 weight percent TiO ₂
Further comprising, a low dielectric glass fiber. 9. The method of claim 8,
The glass composition comprises:
50.0 to 56.0 weight percent SiO ₂ ;
16.0 to 25.0 weight percent of B ₂ O ₃ ;
13.0 to 17.0 weight percent of Al ₂ O ₃ ;
greater than 3.0 weight percent to 7.0 weight percent P ₂ O ₅ ;
greater than 0.25 weight percent to 6.0 weight percent CaO;
up to 4.0 weight percent MgO; and
less than 5.0 weight percent TiO ₂
Further comprising, a low dielectric glass fiber. 9. The method of claim 8,
The glass composition comprises:.
at least 49.0 weight percent SiO ₂ ;
up to 56.5 weight percent SiO ₂ ;
at least 15.5 weight percent B ₂ O ₃ ;
up to 25.5 weight percent B ₂ O ₃ ;
up to 17.50 weight percent Al ₂ O ₃ ;
up to 7.0 weight percent P ₂ O ₅ ;
up to 6.5 weight percent CaO;
up to 4.5 weight percent MgO; and/or
5.5 weight percent or less of one or more of TiO ₂
Further comprising a, low dielectric glass fiber. 9. The method of claim 8,
The glass composition comprises:
at least 50.0 weight percent SiO ₂ ;
up to 56.0 weight percent SiO ₂ ;
at least 16.0 weight percent B ₂ O ₃ ;
up to 25.0 weight percent B ₂ O ₃ ;
up to 17.0 weight percent Al ₂ O ₃ ;
up to 7.0 weight percent P ₂ O ₅ ;
up to 6.0 weight percent CaO;
up to 4.0 weight percent MgO; and/or
5.0 weight percent or less of one or more of TiO ₂
Further comprising a, low dielectric glass fiber. 9. The method of claim 8,
wherein the glass fiber has a dielectric constant of 6 or less and/or a dissipation coefficient of 38x10 ^-4 or less at a frequency of 10 GHz at room temperature. 9. The method of claim 8,
wherein the glass fiber has a dielectric constant of 4.60 or less and/or a dissipation coefficient of 30x10 ^-4 or less at a frequency of 10 GHz at room temperature. 9. The method of claim 8,
wherein the glass fiber has a dielectric constant of 4.55 or less and/or a dissipation coefficient of 25x10 ^-4 or less at a frequency of 10 GHz at room temperature. A fiberglass reinforced article comprising the glass fibers according to claim 8 . 17. The method of claim 16,
wherein the article is a printed circuit board. 9. The method of claim 8,
wherein the glass fibers are formed from a glass composition having an intrinsic network structure that crystallizes into and tends to form alumino-borate mullite crystals. An article comprising the glass fiber according to claim 8, comprising:
If the product is printed circuit board, woven fabric, non-woven fabric, unidirectional fabric, chopped strand, chopped strand mat, composite material ( composite material, and a communication signal transport medium.

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