Glass and methods for determining the dielectric properties of glass.

Abstract

The glass of the present invention is characterized in that, after a constant temperature and humidity test of 85°C and 85% for 1000 hours, the change rate of the dielectric loss tangent at a measurement frequency of 2.45 GHz and a measurement temperature of 25°C is less than 30%.

Description

Technical Field

[0001] This invention relates to glass and a method for measuring the dielectric properties of glass, and more specifically, to glass used as a standard material (dielectric constant standard material) for measuring dielectric properties at frequencies used in fifth-generation mobile communication systems (5G) and a method for measuring the dielectric properties of glass. Background Technology

[0002] Currently, development is underway to prepare for the fifth-generation mobile communication system (5G), and technical research is being conducted to improve the system's speed, transmission capacity, and latency.

[0003] For frequencies used in fifth-generation mobile communication systems (5G), 3.7GHz, 4.5GHz, 28GHz, and 39GHz are envisioned. Generally, the higher the frequency, the greater the dielectric loss of the electrical signal propagating in the system. On the other hand, if the relative permittivity and dielectric loss tangent of the constituent materials surrounding the propagation of the electrical signal are reduced, the dielectric loss of the electrical signal can be reduced (see Non-Patent Literature 1). Therefore, it is desirable to reduce the dielectric properties of the constituent materials.

[0004] However, methods for measuring dielectric properties include, for example, the cavity resonator method and the balanced circular plate resonator method (see Non-Patent Literature 2, 3). Furthermore, the standard substances used for measuring dielectric properties are commonly available Teflon and alumina.

[0005] Non-Patent Documents 4 and 5 show supply plans for dielectric constant standards used when measuring the dielectric properties of constituent materials in the high-frequency domain. Furthermore, Non-Patent Document 4 uses quartz glass and alkali-free glass as candidates for the measurement standard.

[0006] Existing technical documents

[0007] Non-patent literature

[0008] Non-patent literature 1: Journal of the Institute of Electronics Installations, Vol. 22, No. 2 (2019), p. 172, Line Loss, Usui Yusan

[0009] Non-Patent Literature 2: Evaluation of Dielectric Properties / Electromagnetic Absorption Properties of Metals Vol.89 No.2 (2019) P.42 (144) Daisuke Iki

[0010] Non-patent document 3: Sumibe Research Co., Ltd. homepage 1630560467110_0.htm Search date: December 3, 2019

[0011] Non-Patent Document 4: Text from the Technical Information Association Seminar on Low Dielectric Constant, Low Dielectric Loss Tangent, and Reduced Transmission Loss of High-Frequency Substrate Materials (Held October 22, 2013) Presented by Yuto Kato: Measurement Technology and Applications of Dielectric Constant of High-Frequency Substrate Materials (p. 16)

[0012] Non-Patent Document 5: Metrological Standard Renovation Plan (Physical Standard) 1630560467110_1.pdf Search Date: December 3, 2019 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] Teflon and alumina, as mentioned above, have been used as standard substances for determination, but they are hygroscopic. Furthermore, it is known that the dielectric properties in the high-frequency domain change due to moisture. Therefore, if Teflon and alumina are used as standard substances for determination, the reliability of the measured dielectric properties becomes insufficient.

[0015] Furthermore, quartz glass is less readily available and more expensive than other types of glass, making it unsuitable for use as a reference material. Alkali-free glass generally does not possess the low dielectric properties required for fifth-generation mobile communication systems (5G), making it unsuitable as a reference material for dielectric property determination.

[0016] In addition, generally speaking, glasses with low dielectric properties have a high content of B2O3 in their composition, which makes their moisture resistance tend to be lower.

[0017] The present invention was made in view of the above circumstances, and its technical objective is to provide a glass with low dielectric properties and high moisture resistance, and a method for measuring the dielectric properties of the glass.

[0018] means for solving problems

[0019] The inventors discovered, through repeated experiments, that the dielectric properties of a glass are not easily altered by constant temperature and humidity tests, and high-temperature and high-humidity constant temperature tests (unsaturated pressurized water vapor), and this invention is proposed as the present invention. Specifically, the glass of the present invention is characterized by a change rate of less than 30% in the dielectric loss tangent at a measured frequency of 2.45 GHz and a measured temperature of 25 GHz after a constant temperature and humidity test of 85 ℃ and 85% relative humidity for 1000 hours. Here, "glass" as used in the present invention includes not only amorphous glass but also crystalline glass. Furthermore, the dielectric loss tangent at a measured frequency of 2.45 GHz and a measured temperature of 25 ℃ can be measured, for example, by the known cavity resonator method. Moreover, the change rate of the dielectric loss tangent is a value calculated by [(dielectric loss tangent after test - dielectric loss tangent before test) / (dielectric loss tangent after test)] × 100.

[0020] Furthermore, after undergoing a high-temperature and high-humidity constant test (JIS-C0096-2001) at 120°C and 85% relative humidity for 12 hours, the change rate of the dielectric loss tangent at a measurement frequency of 2.45 GHz and a measurement temperature of 25°C is preferably 30% or less. It should be noted that the test apparatus for the aforementioned high-temperature and high-humidity constant test can, for example, be the PC-242HSR2 unsaturated high-speed life test apparatus manufactured by Hirayama Manufacturing Co., Ltd.

[0021] Furthermore, the X-ray intensity of boron obtained by analyzing the glass of the present invention from the outermost surface in the depth direction after undergoing a high-temperature and high-humidity constant test (JIS-C0096-2001) at 120°C and 85% relative humidity for 48 hours is preferably reduced by 5 μm or less, with a depth of 15 μm as a reference. It should be noted that the "depth of boron reduction" is determined as follows: using the glass fracture surface as the analytical sample, elemental analysis is performed from the outermost surface of the glass in the depth direction, and point analysis is performed on the characteristic X-ray intensity value (unit: count) of boron's Kα rays at this point, and the value is determined based on the obtained measurement. It should be noted that for the outermost surface, i.e., at a depth of 0 μm, if the measurement is performed on the fracture surface, the beam diameter of the irradiated X-rays will not reach the fracture surface; therefore, the measurement value of the outermost surface of the glass side is taken as the boron X-ray intensity at a depth of 0 μm. The boron X-ray intensity can be analyzed, for example, using an EPMA (Electron Probe MicroAnalyzer, Shimadzu Corporation EPMA-1720).

[0022] Furthermore, the product of the content (mol%) of B2O3-Al2O3 and the content (mol%) of B2O3-(MgO+CaO+SrO+BaO) in the glass composition of the present invention is preferably 260 or less. This significantly improves moisture resistance. It should be noted that "B2O3-Al2O3" is the value obtained by subtracting the content of Al2O3 from the content of B2O3. "B2O3-(MgO+CaO+SrO+BaO)" is the value obtained by subtracting the total amount of MgO, CaO, SrO, and BaO from the content of B2O3. By increasing the amount of Al2O3 relative to B2O3 and increasing the amount of alkaline earth elements relative to B2O3, phase separation of the glass—that is, the separation into a phase with more B2O3 and a phase with less B2O3—can be suppressed. As a result, the reduction of B2O3 caused by weathering tests can be suppressed.

[0023] Furthermore, the glass of the present invention is preferably crystallized glass. This improves moisture resistance.

[0024] Furthermore, the glass of the present invention preferably contains, in molar percentage, 60-75% SiO2, 0-15% Al2O3, 8-28% B2O3, 0-3% Li2O+Na2O+K2O, and 0-14% MgO+CaO+SrO+BaO, and has a relative permittivity of 6 or less at 25°C and 2.45 GHz. This results in a glass with low dielectric properties and high moisture resistance.

[0025] Furthermore, the glass of the present invention preferably contains, in molar percentage, 75-85% SiO2, 0-5% Al2O3, 10-20% B2O3, 0-5% Li2O, 1-10% Na2O, 0-5% K2O, and 3-10% Li2O+Na2O+K2O, and has a relative permittivity of 6 or less at 25°C and 2.45 GHz. This results in a glass with low dielectric properties and high moisture resistance.

[0026] Furthermore, the glass of the present invention preferably contains, in molar percentage, 55-75% SiO2, 10-20% Al2O3, 2% or more Li2O, 0.5-3% TiO2, 2-5% TiO2 + ZrO2, and 0.1-0.5% SnO2, and has a relative permittivity of 7 or less at 25°C and 2.45 GHz. This results in a glass with low dielectric properties and high moisture resistance.

[0027] Furthermore, the glass of the present invention is preferably used as a standard material for measuring dielectric properties.

[0028] The method for measuring the dielectric properties of the present invention is characterized by using a method for measuring the dielectric properties of a standard substance, wherein the aforementioned glass is used in the standard substance. This allows for long-term, stable measurement of the dielectric properties.

[0029] Furthermore, in the method for measuring the dielectric properties of the present invention, it is preferable to heat the standard substance to be measured at a temperature above the annealing point of glass before measuring the dielectric properties. This allows the standard substance to be restored to its initial dielectric properties should the dielectric properties change. Attached Figure Description

[0030] Figure 1 This is a graph showing the results of boron composition analysis of the glass cross-sections of samples No. 7 and 25 in Example 3.

[0031] Figure 2 The graph shows the effect of changes in the glass surface composition on the dielectric loss tangent for samples No. 7, 25, and 26 in the Example 3 column.

[0032] Figure 3 The following are the reflectance spectra of samples No. 7, 25, and 26 in the Example 3 column. (a) is the reflectance spectrum of sample No. 7, (b) is the reflectance spectrum of sample No. 25, and (c) is the reflectance spectrum of sample No. 26.

[0033] Figure 4 The transmittance spectra of samples No. 7, 25, and 26 in the Example 3 column are shown. (a) is the transmittance spectrum of sample No. 7, (b) is the transmittance spectrum of sample No. 25, and (c) is the transmittance spectrum of sample No. 26.

[0034] Figure 5 This is a graph showing the changes in β-OH values ​​of samples No. 7, 25, and 26 in the Example 3 column.

[0035] Figure 6 The graphs show the relationship between the dielectric loss tangent and the β-OH value at 25°C and 2.45GHz for samples No.7, 25, and 26 in Example 3. (a) shows the relationship between the dielectric loss tangent and the β-OH value at 25°C and 2.45GHz for sample No.7; (b) shows the relationship between the dielectric loss tangent and the β-OH value at 25°C and 2.45GHz for sample No.25; and (c) shows the relationship between the dielectric loss tangent and the β-OH value at 25°C and 2.45GHz for sample No.26. Detailed Implementation

[0036] In the glass of the present invention, after a constant temperature and humidity test at 85°C and 85% relative humidity for 1000 hours, the rate of change of the dielectric loss tangent at a measurement frequency of 2.45 GHz and a measurement temperature of 25°C is preferably 30% or less, 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less. If the above-mentioned rate of change of the dielectric loss tangent is too high, the moisture resistance of the glass is easily reduced, making it unsuitable for use in high-frequency devices, etc.

[0037] In the glass of the present invention, after undergoing a high-temperature and high-humidity constant test (JIS-C0096-2001) at a temperature of 120°C and a relative humidity of 85% for 12 hours, the rate of change of the dielectric loss tangent at a measurement frequency of 2.45 GHz and a measurement temperature of 25°C is preferably 30% or less, 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less. If the above-mentioned rate of change of the dielectric loss tangent is too high, the moisture resistance of the glass is easily reduced, making it unsuitable for use in high-frequency devices, etc.

[0038] In the glass of the present invention, after undergoing a high-temperature and high-humidity constant test (JIS-C0096-2001) at a temperature of 120°C and a relative humidity of 85% for 48 hours, the rate of change of the dielectric loss tangent at a measurement frequency of 2.45 GHz and a measurement temperature of 25°C is preferably 30% or less, 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less. If the above-mentioned rate of change of the dielectric loss tangent is too high, the moisture resistance of the glass is easily reduced, making it unsuitable for use in high-frequency devices, etc.

[0039] In the glass of this invention, after undergoing a high-temperature and high-humidity constant test (JIS-C0096-2001) at 120°C and 85% relative humidity for 48 hours, the depth at which the X-ray intensity of boron, analyzed from the outermost surface in the depth direction, is reduced by 50% with a reference depth of 15 μm, is preferably 5.0 μm or less, 4.9 μm or less, 4.8 μm or less, 4.7 μm or less, 4.6 μm or less, 4.5 μm or less, 4.4 μm or less, 4.3 μm or less, 4.2 μm or less, 4.1 μm or less, 4.0 μm or less, 3.9 μm or less, 3.8 μm or less, 3.7 μm or less, 3.6 μm or less, 3.5 μm or less, 3.4 μm or less, 3.3 μm or less, and 3.2 μm or less. Below, below 3.1μm, below 3.0μm, below 2.9μm, below 2.8μm, below 2.7μm, below 2.6μm, below 2.5μm, below 2.4μm, below 2.3μm, below 2.2μm, below 2.1μm, below 2.0μm, below 1.9μm, below 1.8μm, below 1.7μm, below 1.6μm, below 1.5μm, below 1.4μm, below 1.3μm, below 1.2μm, below 1.1μm, below 1.0μm, below 0.9μm, below 0.8μm, below 0.7μm, below 0.6μm, below 0.5μm, below 0.4μm, below 0.3μm, below 0.2μm, below 0.1μm, below 0.0μm. If the reduction in boron depth is too great, the moisture resistance of the glass will easily decrease, making it unsuitable for use in high-frequency devices, etc.

[0040] In the glass of this invention, after undergoing a high-temperature and high-humidity constant test (JIS-C0096-2001) at 120°C and 85% relative humidity for 48 hours, and then maintaining the glass at its annealing point +30°C for 3 hours, followed by cooling to room temperature at -3°C / min, the depth at which the boron X-ray intensity is analyzed from the outermost surface in the depth direction, with a 50% reduction based on a depth of 15 μm, is preferably 10.0 μm or less, 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, 6.0 μm or less, 5.0 μm or less, 4.9 μm or less, 4.8 μm or less, 4.7 μm or less, 4.6 μm or less, 4.5 μm or less, 4.4 μm or less, 4.3 μm or less, 4.2 μm or less, 4.1 μm or less, 4.0 μm or less, 3.9 μm or less, 3.8 μm or less, and 3.7 μm or less. Below 3.6μm, below 3.5μm, below 3.4μm, below 3.3μm, below 3.2μm, below 3.1μm, below 3.0μm, below 2.9μm, below 2.8μm, below 2.7μm, below 2.6μm, below 2.5μm, below 2.4μm, below 2.3μm, below 2.2μm, below 2.1μm, below 2.0μm, below 1.9μm, 1.8μm Below μm, 1.7μm, 1.6μm, 1.5μm, 1.4μm, 1.3μm, 1.2μm, 1.1μm, 1.0μm, 0.9μm, 0.8μm, 0.7μm, 0.6μm, 0.5μm, 0.4μm, 0.3μm, 0.2μm, 0.1μm, and 0.0μm. When the boron reduction depth is too large at these values, the moisture resistance of the glass tends to decrease, making it unsuitable for use in high-frequency devices, etc.

[0041] The glass of the present invention can have various compositions, but preferably has the compositions described below (glasses A to C). Preferably, the glass of the present invention (glass A) contains, in mole percent, 60-75% SiO2, 0-15% Al2O3, 8-28% B2O3, 0-3% Li2O+Na2O+K2O, and 0-14% MgO+CaO+SrO+BaO. As described above, the reasons for limiting the content of each component are explained below. It should be noted that, unless otherwise specified, the percentages expressed below refer to mole percent.

[0042] The preferred SiO2 content is 60–75%, 61–74%, 62–72%, 63–71%, 64–70%, 64–69.5%, 64–69%, and especially 65–67%. If the SiO2 content is too low, the relative permittivity, dielectric loss tangent, and density tend to increase. Furthermore, moisture resistance tends to decrease. On the other hand, if the SiO2 content is too high, the high-temperature viscosity increases, the meltability decreases, and devitrified crystals such as quartz tend to precipitate during molding.

[0043] Al2O3 is a component that improves Young's modulus and is used to suppress phase separation. Furthermore, it significantly improves moisture resistance. Therefore, the lower limit range of Al2O3 is preferably 0% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, 4% or more, 5% or more, and particularly 6% or more. On the other hand, when the Al2O3 content is too high, the liquidus temperature increases, and the devitrification resistance tends to decrease. Moreover, there is a tendency for the relative permittivity and dielectric loss tangent to increase. Therefore, the upper limit range of Al2O3 is preferably below 15%, 13%, 12%, 11%, 10.9%, 10.8%, 10.7%, 10.6%, 10.5%, 10%, 9.9%, 9.8%, 9.7%, 9.6%, 9.5%, 9.4%, 9.3%, 9.2%, 9.1%, 9.0%, 8.9%, 8.7%, 8.5%, 8.3%, 8.1%, 8%, 7.9%, 7.8%, 7.7%, 7.6%, 7.5%, 7.3%, 7.1%, and especially below 7.0%.

[0044] B₂O₃ is a component that reduces the relative permittivity and dielectric loss tangent, but it also reduces Young's modulus and density. Furthermore, it reduces moisture resistance. However, if the B₂O₃ content is too low, it is difficult to ensure low dielectric properties; in addition, its role as a flux becomes insufficient, high-temperature viscosity increases, and foam quality tends to decrease. Furthermore, achieving low density is difficult. Therefore, the lower limit range of B₂O₃ is preferably 8% or more, 9% or more, 10% or more, 15% or more, 18% or more, 18.1% or more, 18.2% or more, 18.3% or more, 18.4% or more, 18.5% or more, 19% or more, 19.4% or more, 19.5% or more, 19.6% or more, 20% or more, exceeding 20%, and particularly 22% or more. On the other hand, if the B₂O₃ content is too high, heat resistance and chemical durability tend to decrease, or moisture resistance tends to decrease due to phase separation. Therefore, the upper limit range of B2O3 is preferably below 28%, below 27%, below 26%, below 25%, below 24%, and especially below 23%.

[0045] The preferred content of B2O3-Al2O3 is -5% or more, -4% or more, -3% or more, -2% or more, -1% or more, 0% or more, 1% or more, 2% or more, 3% or more, 4% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, and especially 10% or more. If the content of B2O3-Al2O3 is too low, it is difficult to ensure low dielectric properties.

[0046] Alkali metal oxides improve meltability and formability; however, excessive content can lead to increased density, decreased moisture resistance, inappropriately increased coefficient of thermal expansion, decreased thermal shock resistance, or difficulty in matching the coefficient of thermal expansion with surrounding materials. Therefore, the content of Li₂O + Na₂O + K₂O (the total amount of Li₂O, Na₂O, and K₂O) is preferably 0–3%, 0–2%, 0–1%, 0–0.5%, 0–0.2%, 0–0.1%, and particularly 0.001% or more but less than 0.05%. The individual contents of Li₂O, Na₂O, and K₂O are preferably 0–3%, 0–2%, 0–1%, 0–0.5%, 0–0.2%, 0–0.1%, and particularly 0.001% or more but less than 0.01%.

[0047] Alkaline earth metal oxides are components that lower the liquidus temperature, making it less prone to devitrification and crystallization in glass, and also improve meltability and formability. The preferred content of MgO+CaO+SrO+BaO (total amount of MgO, CaO, SrO, and BaO) is 0–14%, 0–12%, 0–10%, 0–8%, 0–7%, 1–7%, 2–7%, 3–9%, and especially 3–6%. If the content of MgO+CaO+SrO+BaO is too low, the resistance to devitrification is easily reduced; furthermore, its role as a flux cannot be fully utilized, and meltability is easily reduced. On the other hand, if the content of MgO+CaO+SrO+BaO is too high, the density increases, making it difficult to achieve lightweight glass; in addition, the coefficient of thermal expansion becomes unduly high, and the thermal shock resistance is easily reduced.

[0048] MgO is a component that reduces high-temperature viscosity and increases meltability without lowering the strain point, and it is the least likely to increase density among alkaline earth metal oxides. Furthermore, it is a component that particularly improves moisture resistance among alkaline earth metals. The preferred MgO content is 0–12%, 0–10%, 0.01–8%, 0.1–6%, 0.2–5%, 0.3–4%, 0.5–3%, and especially 0.8–2%. However, excessive MgO content leads to an increase in liquidus temperature and a decrease in resistance to devitrification. It also makes the glass prone to phase separation and reduces transparency.

[0049] CaO is a component that reduces high-temperature viscosity without lowering the strain point, significantly improves melt flow, and is also the component in the glass A composition system that has a significant effect on improving devitrification resistance. Furthermore, it is a component among alkaline earth metals that improves moisture resistance. Therefore, the preferred lower limit range of CaO is 0% or more, 0.05% or more, 0.1% or more, 1% or more, 1.1% or more, 1.2% or more, 1.3% or more, 1.4% or more, 1.5% or more, and particularly 2% or more. On the other hand, when the CaO content is too high, the coefficient of thermal expansion and density increase inappropriately, or the compositional balance is damaged, which can easily reduce devitrification resistance. Therefore, the preferred upper limit range of CaO is 12% or less, 10% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4.6% or less, 4.5% or less, 4.4% or less, 4% or less, and particularly 3% or less.

[0050] SrO is a component that reduces high-temperature viscosity and improves meltability without lowering the strain point. However, excessive SrO content can easily reduce the liquid phase viscosity. Therefore, the preferred SrO content is 0–10%, 0–8%, 0–7%, 0–6%, 0–5.1%, 0–5%, 0–4.9%, 0–4%, 0–3%, 0–2%, 0–1.5%, 0–1%, 0–0.5%, and especially 0–0.1%.

[0051] BaO is a component that reduces high-temperature viscosity and increases meltability without lowering the strain point. However, excessive BaO content can easily reduce the liquid phase viscosity. Therefore, the preferred BaO content is 0–10%, 0–8%, 0–7%, 0–6%, 0–5%, 0–4%, 0–3%, 0–2%, 0–1.5%, 0–1%, 0–0.5%, and especially above 0% and below 0.1%.

[0052] When the molar ratio (MgO+CaO+SrO+BaO) / (SiO2+Al2O3+B2O3) is too high, the moisture resistance tends to decrease. Furthermore, when forming through-holes through etching, there is a tendency for the etching speed to increase and the shape of the through-holes to become distorted (flattened). Additionally, when forming through-holes through laser irradiation, there is a tendency for the opening precision to decrease. On the other hand, when the molar ratio (MgO+CaO+SrO+BaO) / (SiO2+Al2O3+B2O3) is too low, the high-temperature viscosity increases, and the melting temperature becomes higher, thus easily leading to a higher manufacturing cost for the glass plate. Therefore, the molar ratio (MgO+CaO+SrO+BaO) / (SiO2+Al2O3+B2O3) is preferably 0.001–0.4, 0.005–0.35, 0.010–0.30, 0.020–0.25, 0.030–0.20, 0.035–0.15, 0.040–0.14, 0.045–0.13, and particularly 0.050–0.10. It should be noted that "(molar ratio (MgO+CaO+SrO+BaO) / (SiO2+Al2O3+B2O3))" refers to the value obtained by dividing the content of MgO+CaO+SrO+BaO by the content of SiO2+Al2O3+B2O3.

[0053] When the molar ratio (MgO+CaO+SrO+BaO) / Al2O3 is too small, the devitrification resistance decreases, making it difficult to form into plates using the overflow pull-down method. On the other hand, when the molar ratio (MgO+CaO+SrO+BaO) / Al2O3 is too large, there are concerns about an undue increase in density and coefficient of thermal expansion. Therefore, the preferred molar ratio (MgO+CaO+SrO+BaO) / Al2O3 is 0.1–2.0, 0.1–1.5, 0.1–1.2, 0.2–1.2, 0.3–1.2, 0.4–1.1, and particularly 0.5–1.0. It should be noted that "(MgO+CaO+SrO+BaO) / Al2O3" refers to the value obtained by dividing the content of MgO+CaO+SrO+BaO by the content of Al2O3.

[0054] The molar ratio (SrO+BaO) / B2O3 is preferably 1.0 or less, 0.5 or less, 0.2 or less, 0.1 or less, 0.05 or less, 0.03 or less, and especially 0.02 or less. When the molar ratio (SrO+BaO) / B2O3 is too large, it is difficult to ensure low dielectric properties and difficult to increase the liquid phase viscosity. It should be noted that "SrO+BaO" refers to the total amount of SrO and BaO. Furthermore, "(SrO+BaO) / B2O3" refers to the value obtained by dividing the content of SrO+BaO by the content of B2O3.

[0055] The content of B2O3-(MgO+CaO+SrO+BaO) is preferably -5% or more, 0% or more, 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, and especially 12% or more. When the content of B2O3-(MgO+CaO+SrO+BaO) is too low, it is difficult to ensure low dielectric properties, and the density tends to increase, and the Young's modulus tends to decrease.

[0056] The molar ratio (SrO+BaO) / (MgO+CaO) is preferably 400 or less, 300 or less, 100 or less, 50 or less, 10 or less, 5 or less, 2 or less, 1 or less, 0.8 or less, 0.5 or less, and especially 0.3 or less. When the molar ratio (SrO+BaO) / (MgO+CaO) is too large, it is difficult to ensure low dielectric properties, and the density tends to increase.

[0057] The product of the content (mol%) of B2O3-Al2O3 and the content (mol%) of B2O3-(MgO+CaO+SrO+BaO) is preferably 600 or less, 550 or less, 500 or less, 450 or less, 400 or less, 350 or less, 340 or less, 330 or less, 320 or less, 310 or less, 300 or less, 290 or less, 280 or less, 270 or less, and especially 260 or less. When the product of the content of B2O3-Al2O3 and the content of B2O3-(MgO+CaO+SrO+BaO) is too large, it is difficult to ensure moisture resistance, and Young's modulus tends to decrease. Furthermore, the product of the content of B2O3-Al2O3 and the content of B2O3-(MgO+CaO+SrO+BaO) is preferably 1 or more, 5 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, and especially 100 or more. If the product of the content of B2O3-Al2O3 and the content of B2O3-(MgO+CaO+SrO+BaO) is too small, it is difficult to ensure low dielectric properties, and the coefficient of thermal expansion is prone to decrease.

[0058] In addition to the ingredients mentioned above, the following ingredients may also be incorporated into the composition.

[0059] ZnO is a component that improves melt flow, but when it is present in large quantities in the composition, the glass is prone to devitrification and the density tends to increase. Therefore, the ZnO content is preferably 0-5%, 0-3%, 0-0.5%, 0-0.3%, and especially 0-0.1%.

[0060] ZrO2 is a component that improves Young's modulus. The preferred ZrO2 content is 0-5%, 0-3%, 0-0.5%, 0-0.2%, 0-0.16%, 0-0.1%, and especially 0-0.02%. When the ZrO2 content is too high, the liquidus temperature rises, and devitrification crystallization of zircon is more likely to occur.

[0061] TiO2 reduces high-temperature viscosity and improves melt flow, and it also inhibits solarization. However, when it is present in large quantities, the glass is prone to coloration and its transmittance tends to decrease. Therefore, the preferred TiO2 content is 0–5%, 0–3%, 0–1%, 0–0.1%, and especially 0–0.02%.

[0062] P2O5 is a component that improves devitrification resistance, but when it is present in large quantities in the composition, it can cause glass phase separation, easily lead to emulsification, and raise concerns about a significant reduction in moisture resistance. Therefore, the preferred content of P2O5 is 0–5%, 0–1%, 0–0.5%, and especially 0–0.1%.

[0063] SnO2 is a component with good clarifying properties in high-temperature regions and also reduces high-temperature viscosity. The preferred SnO2 content is 0-1%, 0.01-0.5%, 0.05-0.3%, and especially 0.07-0.2%. When the SnO2 content is too high, devitrifying SnO2 crystals are more likely to precipitate in the glass.

[0064] Fe2O3 is an impurity component or a component that can be introduced as a clarifying agent. However, there is a concern that excessive Fe2O3 content may reduce ultraviolet transmittance. Therefore, the Fe2O3 content is preferably 0.05% or less, 0.03% or less, and particularly 0.02% or less. Here, "Fe2O3" as used in this invention includes divalent iron oxide and trivalent iron oxide, with divalent iron oxide being converted to Fe2O3. It should be noted that other multivalent oxides can also be treated similarly using the oxides described above as a reference.

[0065] SnO2 is preferred as a clarifying agent. CeO2, SO3, C, and metal powder (such as Al, Si, etc.) can be added up to 1% as a clarifying agent, as long as it does not impair the glass properties.

[0066] As2O3, Sb2O3, F, and Cl also function effectively as clarifying agents. In this invention, the presence of these components is not excluded, but from an environmental point of view, the content of these components is preferably less than 0.1%, and particularly preferably less than 0.05%.

[0067] Preferably, the glass (glass B) of the present invention contains, as a composition, 75-85% SiO2, 0-5% Al2O3, 10-20% B2O3, 0-5% Li2O, 1-10% Na2O, 0-5% K2O, and 3-10% Li2O+Na2O+K2O in molar percentage. As described above, the reasons for limiting the content of each component are explained below. It should be noted that, unless otherwise specified, the percentages expressed below refer to molar percentages.

[0068] SiO2 is the main component forming the glass framework structure. The preferred SiO2 content is 75–85%, 77–84%, 78–83%, 77–82%, and especially 77–81%. If the SiO2 content is too low, the relative permittivity, dielectric loss tangent, and density tend to increase. Furthermore, moisture resistance tends to decrease. On the other hand, if the SiO2 content is too high, the high-temperature viscosity increases, the meltability decreases, and devitrifying crystals such as quartz tend to precipitate during molding.

[0069] Al2O3 is a component that improves chemical durability, mechanical strength, and resistance to devitrification. The preferred content of Al2O3 is 0-5%, 1-4%, 1.1-3%, and especially 2-3%. When the content of Al2O3 is too high, the viscosity at high temperature increases, and the meltability and formability are easily reduced.

[0070] B₂O₃ is a component that forms the glass framework structure and reduces viscosity at high temperatures. The preferred B₂O₃ content is 10–20%, 10–18%, 11–15%, and particularly 12–15%. Excessive B₂O₃ content can easily lead to phase separation in the glass. If phase separation occurs, the coefficient of thermal expansion and dielectric properties become uneven, and chemical durability is easily reduced. Furthermore, the evaporation of components from the molten glass increases, making it easier to form a heterogeneous layer on the surface of the molten glass, thus reducing the homogeneity of the glass. On the other hand, insufficient B₂O₃ content results in excessively high viscosity in the glass. Moreover, it becomes difficult to maintain low dielectric properties.

[0071] Alkali metal oxides are components that reduce the viscosity of glass and increase its meltability, but they also increase the coefficient of thermal expansion and dielectric properties. The preferred content of Li₂O + Na₂O + K₂O is 3–10%, 3.5–8%, and particularly 4–5%. If the content of Li₂O + Na₂O + K₂O is too low, the viscosity of the glass increases, and its meltability tends to decrease. On the other hand, if the content of Li₂O + Na₂O + K₂O is too high, the coefficient of thermal expansion and dielectric properties increase, and the thermal shock resistance tends to decrease.

[0072] Li₂O is a component that reduces viscosity and improves meltability at high temperatures. The preferred content of Li₂O is 0–5%, 0–3%, and especially 0–1%. When the content of Li₂O is too high, the coefficient of thermal expansion becomes too high, and the thermal shock resistance is easily reduced. Moreover, the dielectric properties become too high.

[0073] Na₂O is a component that reduces viscosity at high temperatures and improves meltability. The preferred Na₂O content is 1–10%, 2–7%, 3–6.5%, and especially 4–6%. If the Na₂O content is too low, the viscosity at high temperatures will increase, and meltability will easily decrease. On the other hand, if the Na₂O content is too high, the coefficient of thermal expansion and dielectric properties will become too high.

[0074] K2O is a component that reduces viscosity and improves meltability at high temperatures. The preferred K2O content is 0-5%, 0-3%, and especially 0-1%. When the K2O content is too high, the coefficient of thermal expansion becomes too high, and the thermal shock resistance is easily reduced. Moreover, the dielectric properties become too high.

[0075] In addition to the components mentioned above, other components may also be included. For example, to improve the coefficient of thermal expansion, dielectric properties, and high-temperature viscosity, MgO, CaO, SrO, BaO, ZnO, TiO2, ZrO2, SnO2, P2O5, Cr2O3, Sb2O3, SO2, Cl2, PbO, La2O3, WO3, Co3O4, Nb2O5, Y2O3, CeO2, etc., may be included. It should be noted that the content of these components, in total, is preferably set to 3% or less.

[0076] In addition, as trace components, trace elements such as H2, CO2, CO, He, Ne, Ar, and N2 can be contained up to 0.1% in total. Furthermore, as long as it does not adversely affect the dielectric properties, precious metal elements such as Pt and Rh can be contained in the glass up to 500 ppm in total.

[0077] Preferably, the glass (glass C) of the present invention is a crystallized glass, and its composition, in molar percentage, contains 55-75% SiO2, 10-20% Al2O3, 2% or more Li2O, 0.5-3% TiO2, 2-5% TiO2 + ZrO2, and 0.1-0.5% SnO2. As described above, the reasons for limiting the content of each component are explained below. It should be noted that, unless otherwise specified, the percentages expressed below refer to molar percentages.

[0078] SiO2 forms the framework of glass and constitutes the Li2O-Al2O3-SiO2 crystal system. It also reduces dielectric properties. The preferred SiO2 content is 55–75%, 58–74%, 60–74%, and particularly 65–73%. Insufficient SiO2 content tends to increase the coefficient of thermal expansion, making it difficult to obtain glass containing crystals with excellent thermal shock resistance. Furthermore, it tends to reduce chemical durability and moisture resistance. On the other hand, excessive SiO2 content reduces melt flow or increases glass viscosity, making it difficult to clarify or form the glass.

[0079] Al2O3 forms the framework of glass and constitutes the Li2O-Al2O3-SiO2 crystal system. Furthermore, the presence of residual glass phases in crystallized glass can reduce the enhancement of coloration by TiO2 and Fe2O3 caused by SnO2. The preferred Al2O3 content is 10–20%, 11–18%, and particularly 12–17%. Insufficient Al2O3 content tends to increase the coefficient of thermal expansion, making it difficult to obtain glass with excellent thermal shock resistance. Additionally, it tends to reduce chemical durability and moisture resistance. Furthermore, it is difficult to achieve the effect of reducing the enhancement of coloration by TiO2 and Fe2O3 caused by SnO2. On the other hand, excessive Al2O3 content reduces meltability or increases glass viscosity, tending to make it difficult to clarify or form. Additionally, it tends to cause mullite crystallization and devitrification, making the glass less prone to breakage.

[0080] Li₂O is a component constituting the Li₂O-Al₂O₃-SiO₂ crystal system. It significantly affects crystallinity, reduces glass viscosity, and improves melt flow and formability. The preferred Li₂O content is 2% or more, 2.5% or more, 3% or more, 4% or more, 5% or more, and especially 6% or more. If the Li₂O content is too low, mullite crystals tend to precipitate, leading to glass devitrification. Furthermore, during glass crystallization, the Li₂O-Al₂O₃-SiO₂ crystal system is difficult to precipitate, making it difficult to obtain glass with excellent thermal shock resistance. In addition, reduced melt flow or increased glass viscosity tends to make the glass difficult to clarify or form. On the other hand, if the Li₂O content is too high, crystallinity becomes excessive, leading to glass devitrification and making the glass less prone to breakage. Furthermore, moisture resistance also decreases. Therefore, the preferred Li₂O content is 10% or less, 9.5% or less, and especially 9% or less.

[0081] TiO2 is used as a nucleating agent to induce crystal precipitation. The preferred TiO2 content is 0.5–3%, 0.8–2.3%, 1–2%, 1.1–1.9%, 1.2–1.8%, 1.3–1.7%, 1.5–1.7%, and particularly 1.6–1.7%. Excessive TiO2 content tends to increase color intensity and may cause glass devitrification, making it less prone to breakage. Conversely, insufficient TiO2 content may prevent adequate crystal nucleation, leading to coarse crystal precipitation, cloudiness, or breakage.

[0082] In addition to the ingredients mentioned above, other ingredients may also be introduced, such as those listed below.

[0083] MgO is a component that is dissolved in the Li₂O-Al₂O₃-SiO₂ crystal system and has the effect of increasing the coefficient of thermal expansion of the Li₂O-Al₂O₃-SiO₂ crystal system. The preferred content of MgO is 0-2%, 0.1-1.5%, 0.3-1.3%, and especially 0.5-1.2%. When the content of MgO is too high, the crystallinity becomes too strong, and the glass is not easily broken.

[0084] Like MgO, ZnO is a component that is dissolved in the Li₂O-Al₂O₃-SiO₂ crystal system. The preferred ZnO content is 0–2%, 0–1.5%, and particularly 0.1–1.2%. Excessive ZnO content leads to overly strong crystallinity, thus a tendency for glass devitrification occurs if molding is performed while slowly cooling. Consequently, the glass becomes easily broken, making processes such as float glass molding difficult.

[0085] It should be noted that the content of each component of SrO and CaO is not particularly limited as long as it meets the above range. For example, for SrO, it is preferred to limit it to 0.5% or less, especially 0.3% or less, and for CaO, it is preferred to limit it to 0.2% or less, especially 0.1% or less.

[0086] SnO2 is the component that functions as a clarifying agent. The preferred SnO2 content is 0.1–0.5%, 0.1–0.4%, and particularly 0.1–0.3%. When the SnO2 content is less than 0.1%, it is difficult to achieve the desired clarifying effect. On the other hand, if the SnO2 content is too high, the coloring of TiO2 and Fe2O3 becomes too strong, and the glass easily takes on a yellowish tint. Furthermore, it is prone to devitrification.

[0087] Fe2O3 is a component mixed in as an impurity. The Fe2O3 content is preferably below 300 ppm, below 250 ppm, and especially below 200 ppm. The lower the Fe2O3 content, the less coloring, which is preferred. However, setting it to a range such as below 60 ppm requires the use of high-purity raw materials, which can easily increase the manufacturing cost of glass.

[0088] Like TiO2, ZrO2 is a nucleating agent used to induce crystallization during the crystallization process. The preferred ZrO2 content is 0–3%, 0.1–2.5%, and particularly 0.5–2.3%. Excessive ZrO2 content can lead to devitrification during glass melting, making glass forming difficult.

[0089] The content of TiO2+ZrO2 (the total amount of TiO2 and ZrO2) is preferably 2-5%, 2.2-4.5%, and particularly 2.3-3.8%. When the content of TiO2+ZrO2 is within the above range, glass with a desired hue and high transparency can be obtained.

[0090] B2O3 is a component that promotes the dissolution of SiO2 raw materials during the melting process. The content of B2O3 is preferably 0-2%, especially 0% or more but less than 1%. When the content of B2O3 is too high, there is a tendency for heat resistance to be compromised. In addition, the moisture resistance also decreases.

[0091] P2O5 is a component that promotes phase separation and facilitates the formation of crystal nuclei. The preferred content of P2O5 is 0-3%, 0.1-2%, and especially 0.2-1%. When the content of P2O5 is too high, the glass is prone to phase separation during the melting process, making it difficult to obtain glass with the desired composition, and there is a tendency for it to become opaque.

[0092] In addition, to reduce the viscosity of the glass and improve its meltability and formability, 0-2% (especially 0.1-2%) of Na₂O, K₂O, and BaO can be added by weight. However, excessive amounts of these components can easily cause the glass to devitrify.

[0093] The glass of the present invention preferably has the following characteristics.

[0094] The relative permittivity at 25℃ and 10GHz is preferably below 7.0, 6.9, 6.8, 6.7, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1, 6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1, 5.0, 4.9, 4.8, 4.7, 4.6, and especially below 4.5. When the relative permittivity is too high, the transmission loss of electrical signals to high-frequency devices tends to increase.

[0095] At 25℃ and 10GHz, the dielectric loss tangent is preferably below 0.01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004, and especially below 0.003. When the dielectric loss tangent is too high, the transmission loss of electrical signals to high-frequency devices tends to increase.

[0096] The relative permittivity at 25℃ and 2.45GHz is preferably below 7.0, 6.9, 6.8, 6.7, 6.6, 6.5, 6.4, 6.3, 6.2, 6.1, 6.0, 5.9, 5.8, 5.7, 5.6, 5.5, 5.4, 5.3, 5.2, 5.1, 5.0, 4.9, 4.8, 4.7, 4.6, and especially below 4.5. When the relative permittivity is too high, the transmission loss of electrical signals to high-frequency devices tends to increase.

[0097] At 25℃ and 2.45GHz, the dielectric loss tangent is preferably below 0.01, 0.009, 0.008, 0.007, 0.006, 0.005, 0.004, and especially below 0.003. When the dielectric loss tangent is too high, the transmission loss of the electrical signal to the high-frequency device is likely to increase.

[0098] The coefficient of thermal expansion in the temperature range of 30–380℃ is preferably 0 × 10⁻⁶. -7 ~60×10 -7 / ℃, 10×10 -7~55×10 -7 / ℃, 20×10 -7 ~50×10 -7 / ℃, 22×10 -7 ~48×10 -7 / ℃, 23×10 -7 ~47×10 -7 / ℃, 25×10 -7 ~46×10 -7 / ℃, 28×10 -7 ~45×10 -7 / ℃, 30×10 -7 ~43×10 -7 / ℃, 32×10 -7 ~41×10 -7 / ℃, especially 35×10 -7 ~39×10 -7 / ℃. When the coefficient of thermal expansion in the temperature range of 30~380℃ becomes outside the above range, it is difficult to match the coefficient of thermal expansion of various surrounding components.

[0099] The preferred Young's modulus is above 40 GPa, 41 GPa, 43 GPa, 45 GPa, 47 GPa, 50 GPa, 51 GPa, 52 GPa, 53 GPa, 54 GPa, and especially above 55 GPa. If the Young's modulus is too low, the glass is prone to bending, which can easily lead to poor wiring when manufacturing high-frequency devices.

[0100] The refractive index nd (measured at a wavelength of 587.6 nm) is preferably 1.55 or less, 1.54 or less, 1.53 or less, 1.52 or less, 1.51 or less, 1.50 or less, 1.495 or less, 1.490 or less, 1.488 or less, 1.487 or less, 1.486 or less, 1.485 or less, 1.484 or less, 1.483 or less, 1.482 or less, 1.481 or less, 1.480 or less, and especially 1.479 or less. When the refractive index is too high, the reflectivity at the air-glass interface increases, thus reducing the intensity of transmitted light to the back of the glass, which can easily lead to poor wiring when manufacturing high-frequency devices. Here, "refractive index" refers to the value measured using a commercially available refractive index meter, such as the Shimadzu KPR-2000 manufactured by Shimadzu Corporation.

[0101] The strain point is preferably above 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, and especially above 590℃. If the strain point is too low, it is sometimes necessary to heat the organic resin layer covering the wiring to cure during the fabrication of high-frequency devices. Glass is prone to thermal shrinkage, thus wiring defects are likely to occur during the fabrication of high-frequency devices.

[0102] The preferred liquid phase viscosity is 10. 3.4 dPa·s or more, 10 3.6 dPa·s or more, 10 3.8 dPa·s or more, 10 4.0 dPa.s or more, 10 4.2 dPa·s or more, 10 4.6 dPa·s or more, 10 4.8 dPa.s or more, 10 5.0 dPa·s and above, especially 10 5.2 Above dPa·s. When the liquid phase viscosity is too low, the glass is prone to devitrification during forming.

[0103] The preferred β-OH value is 1.1 mm. -1 Below, 0.6mm -1 Below, 0.55mm -1 Below, 0.5mm -1 Below, 0.45mm -1 Below, 0.4mm -1 Below, 0.35mm -1 Below, 0.3mm -1 Below, 0.25mm -1 Below, 0.2mm -1 Below, 0.15mm -1 The following, especially 0.1mm -1 The following applies. When the β-OH value is too high, it is difficult to ensure low dielectric properties. It should be noted that the "β-OH value" is a value calculated using a commercially available Fourier transform infrared spectrophotometer (FT-IR) and the following mathematical formula.

[0104] β-OH value = (1 / X)log(T1 / T2)

[0105] X: Plate thickness (mm)

[0106] T1: Reference wavelength 3846cm -1 Transmittance (%)

[0107] T2: Hydroxyl absorption wavelength 3600 cm⁻¹ -1 Minimum transmittance (%) in the vicinity

[0108] The heat shrinkage rate when heated at a rate of 5°C / min, held at 500°C for 1 hour, and cooled at a rate of 5°C / min is preferably 30 ppm or less, 25 ppm or less, 20 ppm or less, and especially 18 ppm or less. If this heat shrinkage rate is too high, when manufacturing high-frequency devices, it is sometimes necessary to cure the organic resin layer that is used to protect the wiring by heating. The glass is prone to heat shrinkage, so poor wiring is likely to occur when manufacturing high-frequency devices.

[0109] In the glass of this invention, the thickness (plate thickness in the case of a plate) is preferably 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, 3 mm or less, 2 mm or less, 1 mm or less, 0.9 mm or less, 0.8 mm or less, 0.7 mm or less, 0.6 mm or less, 0.5 mm or less, 0.4 mm or less, and particularly 0.3 mm or less. When the thickness is too large, it becomes difficult to reduce the weight and miniaturize high-frequency devices.

[0110] The arithmetic mean roughness Ra of the surface is preferably 100 nm or less, 50 nm or less, 20 nm or less, 10 nm or less, 5 nm or less, 2 nm or less, 1 nm or less, and especially 0.5 nm or less. The smoother the surface quality, the smaller the arithmetic mean roughness Ra of the metal wiring formed on the glass surface, thus reducing the resistance loss generated when current flows through the metal wiring of high-frequency devices. Moreover, the glass is less prone to breakage. On the other hand, the arithmetic mean roughness Ra of the surface is preferably 0.1 nm or more, 0.2 nm or more, and especially 0.5 nm or more. The rougher the arithmetic mean roughness Ra of the surface, the less likely the metal wiring and functional film formed on the glass surface are to peel off. It should be noted that the "arithmetic mean roughness Ra" can be measured using a stylus surface roughness meter or an atomic force microscope (AFM).

[0111] The glass of the present invention is preferably formed by an overflow-draw method. This allows for the efficient production of unpolished glass sheets with good surface quality. Besides the overflow-draw method, various other forming methods can be used. For example, slit-draw, float glass, and roll forming methods can be employed.

[0112] The method for measuring the dielectric properties of the present invention is characterized by using a standard material for measuring the dielectric properties, wherein the aforementioned glass is used as the standard material. If the glass of the present invention is used as the standard material, the dielectric properties can be measured stably over a long period.

[0113] In the method for measuring the dielectric properties of the present invention, the frequency at which the dielectric properties are measured is preferably 1 GHz or higher, 2 GHz or higher, 3 GHz or higher, 4 GHz or higher, 5 GHz or higher, 6 GHz or higher, 7 GHz or higher, 8 GHz or higher, 9 GHz or higher, and particularly 10 GHz or higher, and preferably 200 GHz or lower, 150 GHz or lower, 120 GHz or lower, and particularly 100 GHz or lower. When the measurement frequency falls outside the above range, it becomes difficult to evaluate the dielectric properties of the constituent materials of high-frequency devices used in 5G and the like.

[0114] In the method for measuring the dielectric properties of the present invention, the preferred measurement temperature is -40 to 150°C, -30 to 130°C, -20 to 120°C, -10 to 110°C, 0 to 100°C, 10 to 90°C, 20 to 80°C, and particularly 25 to 70°C. When the measurement temperature falls outside the above range, it becomes difficult to evaluate the dielectric properties of the constituent materials of high-frequency devices used in 5G and the like.

[0115] In the method for measuring the dielectric properties of the present invention, it is preferable to heat-treat the glass used as the standard material before measurement. The preferred heating temperature is above the annealing point of the glass, above the annealing point +1°C, above the annealing point +2°C, above the annealing point +3°C, above the annealing point +5°C, above the annealing point +10°C, above the annealing point +15°C, above the annealing point +20°C, above the annealing point +25°C, and particularly above the annealing point +29°C. Higher heating temperatures result in lower moisture content in the glass; however, excessively high heating temperatures may cause the glass to soften and deform. Therefore, the preferred heating temperature is below the softening point, below -100℃, below -200℃, below -250℃, below -280℃, below -300℃, below -320℃, below -330℃, below -340℃, and especially below -350℃. The preferred heating time is 10 minutes or more, 20 minutes or more, 30 minutes or more, 40 minutes or more, 50 minutes or more, 60 minutes or more, 70 minutes or more, 80 minutes or more, 90 minutes or more, 100 minutes or more, 110 minutes or more, 120 minutes or more, 130 minutes or more, 140 minutes or more, 150 minutes or more, 160 minutes or more, 170 minutes or more, and especially 180 minutes or more. The longer the heating time, the lower the moisture content in the glass; however, excessively long heating times reduce the measurement efficiency. Therefore, the heating time is preferably less than 1000 minutes, less than 900 minutes, less than 800 minutes, less than 700 minutes, less than 600 minutes, less than 500 minutes, less than 400 minutes, and especially less than 300 minutes.

[0116] Example 1

[0117] The present invention will now be described in detail based on embodiments. It should be noted that the following embodiments are merely illustrative and are not intended to limit the invention in any way.

[0118] Tables 1 to 6 show the embodiments (samples No. 1 to 16, 21, 26, 27, 28) and comparative examples (samples No. 17 to 20, 22 to 25) of the present invention.

[0119] [Table 1]

[0120]

[0121] [Table 2]

[0122]

[0123] [Table 3]

[0124]

[0125] [Table 4]

[0126]

[0127] [Table 5]

[0128]

[0129] [Table 6]

[0130]

[0131] Samples No. 1 to 28 were prepared as described below. First, glass raw materials prepared according to the composition shown in the table were placed in a platinum crucible and melted at 1650°C for 24 hours. The melt was then poured onto a carbon plate and shaped into a flat plate. For the glass of sample No. 28, after nucleation treatment by heating at 770°C for 3 hours, a further crystallization growth treatment was performed at 880°C for 1 hour to crystallize the glass. Next, for each sample obtained, the glass was held at the annealing point +30°C for 30 minutes, cooled to room temperature at -3°C / min, and the density, strain point Ps, annealing point Ta, softening point Ts, and 10... 4.0 Temperature at dPa·s, 10 3.0 Temperature at dPa·s, 10 2.5The following parameters were evaluated: temperature at dPa·s, liquid phase temperature TL, liquid phase viscosity logηTL, β-OH value, coefficient of thermal expansion α, Young's modulus, rigidity, Poisson's ratio, relative permittivity at 25℃ and 2.45GHz, dielectric loss tangent at 25℃ and 2.45GHz, and constant temperature and humidity tests under various test conditions, as well as the relative permittivity at 25℃ and 2.45GHz after high temperature and high humidity constant tests, and dielectric loss tangent at 25℃ and 2.45GHz.

[0132] Density is a value determined using the well-known Archimedes method.

[0133] The strain point Ps, annealing point Ta, and softening point Ts are values ​​determined based on the methods of ASTM C336 and C338.

[0134] 10 4.0 Temperature at dPa·s, 10 3.0 Temperature at dPa·s and 10 2.5 The temperature at dPa·s was determined using the platinum ball pulling method.

[0135] The liquid phase temperature TL is determined by placing glass powder that has passed through a standard sieve of 30 mesh (500 μm) but remains on 50 mesh (300 μm) into a platinum boat, keeping it in a temperature gradient furnace for 24 hours, and measuring the temperature at which crystallization occurs.

[0136] The liquid phase viscosity logηTL is a value obtained by measuring the viscosity of glass at the liquid phase temperature TL using the platinum ball pulling method.

[0137] The β-OH value was determined using the method described above.

[0138] The coefficient of thermal expansion α is a value measured using a thermal expansion meter, and it is the average value over a recorded temperature range.

[0139] Young's modulus and stiffness ratio are values ​​determined by the resonance method, and Poisson's ratio is a value calculated based on these values.

[0140] The refractive index (nd, nC, nF, ne, ng, nh, ni, nF', LD785, LD1310, LD1550) is a value determined using the well-known V-block method, for example, using a commercially available refractive index meter KPR-2000 (manufactured by Shimadzu Corporation). Furthermore, the Abbe number vd is a value expressed by the formula (nd-1) / (nF-nC).

[0141] The relative permittivity and dielectric loss tangent at 25℃ and 2.45GHz are values ​​measured using the well-known cavity resonator method. It should be noted that 2.45GHz is the air resonance frequency of the cavity resonator.

[0142] The constant temperature and humidity test was conducted using a commercially available high temperature and high humidity constant temperature test chamber under conditions of 85℃, 85% relative humidity, and 1000 hours. The rate of change of the dielectric loss tangent (tanδ rate of change) was calculated by [(dielectric loss tangent after test - dielectric loss tangent before test) / (dielectric loss tangent after test)] × 100.

[0143] The high temperature and high humidity constant temperature test was conducted using the conditions described in JIS-C0096-2001, at a temperature of 120℃, a relative humidity of 85%, and a test duration of 12 or 48 hours, using a commercially available high temperature and high humidity constant temperature test chamber. The rate of change of the dielectric loss tangent (tanδ rate of change) was calculated by [(dielectric loss tangent after test - dielectric loss tangent before test) / (dielectric loss tangent after test)] × 100.

[0144] After constant temperature and humidity test and constant high temperature and humidity test, the dielectric loss tangent of samples No.1 to 16, 21, 26, 27, and 28 at a measured frequency of 2.45 GHz and a measured temperature of 25 ℃ remained almost unchanged. However, the dielectric loss tangent of samples No.17 to 20 and 22 to 25 at a measured frequency of 2.45 GHz and a measured temperature of 25 ℃ changed significantly.

[0145] Example 2

[0146] Various heat treatments were applied to each sample after the constant temperature and humidity test and the constant temperature and humidity test. The results are shown in Tables 7-9.

[0147] [Table 7]

[0148]

[0149] [Table 8]

[0150]

[0151] [Table 9]

[0152]

[0153] First, after drying at 100°C for 24 hours, the dielectric loss tangent at a measurement frequency of 2.45 GHz and a measurement temperature of 25°C was measured, and the dielectric loss tangent showed almost no change.

[0154] Next, for each sample after the constant temperature and humidity test and the constant high temperature and humidity test, the sample was kept at 30°C above its annealing point for 30 minutes or 3 hours, and then cooled to room temperature at -3°C / min. The dielectric loss tangent at a measurement frequency of 2.45 GHz and a measurement temperature of 25°C was then measured.

[0155] According to Tables 4-6, for samples No. 1-28, there is a tendency that the longer the heating time, the closer the sample's value is to that before the constant temperature and humidity test and the constant high temperature and humidity test. Therefore, it can be concluded that by measuring the dielectric properties of a standard substance and performing a prescribed heating treatment, the dielectric properties can be restored to their initial state when the dielectric properties change.

[0156] Example 3

[0157] To investigate the mechanism of the change in the dielectric loss tangent, the following experiments were conducted on samples No. 7, 25, and 26.

[0158] First, for samples No. 7 and 25, the X-ray intensity of boron in the glass cross section was analyzed before and after the high temperature and high humidity constant test under the conditions of 120℃, 85% relative humidity and 48 hours. In addition, for sample No. 25, after holding at the annealing point +30℃ for 3 hours, the X-ray intensity of boron in the glass cross section was analyzed after cooling to room temperature at -3℃ / min.

[0159] Here, the X-ray intensity of boron distributed along the depth direction of the cross-section was analyzed using an EPMA (Electron Probe Micro Analyzer, Shimadzu EPMA-1720). Using the glass fracture surfaces before and after heat treatment as analytical samples, the characteristic X-ray intensity values ​​(unit: counts) of Kα rays of boron at positions (depths) from the outermost surface of the glass toward depths of 0 μm, 1.5 μm, 2.5 μm, 5 μm, 10 μm, and 15 μm were calculated through point analysis to confirm the distribution of boron X-ray intensity along the depth direction of the glass. Regarding depth 0 μm, if the fracture surface is measured, the beam diameter of the irradiated X-rays will not reach the fracture surface; therefore, the measurement value at the outermost surface of the glass side is taken as the boron X-ray intensity at depth 0 μm. It should be noted that the measurement conditions were set as follows: accelerating voltage: 15kV, beam current: 20nA, beam diameter: minimum, measurement time: 10 sec. / point, and measured element: B (BKα: Wavelength). (68.486). The results are shown in Figure 1 .

[0160] The results of compositional analysis showed that in specimen No. 25 after the high temperature and humidity constant test, the X-ray intensity of boron decreased from the outermost surface to a depth of 1.5 μm compared to before the test. Furthermore, after heat treatment, the X-ray intensity of boron decreased to a depth of 2.5 μm compared to before the test. On the other hand, in specimen No. 7 after the high temperature and humidity constant test, the X-ray intensity of boron in the depth direction remained unchanged compared to before the test. For specimen No. 26, although not measured, based on the behavior of the change in dielectric properties and its similar glass composition, it is presumed that the same phenomenon as in specimen No. 25 occurred.

[0161] Next, the effect of changes in the glass surface composition on the dielectric loss tangent was investigated for samples No. 7, 25, and 26. After a high-temperature and high-humidity constant test was conducted at 120°C and 85% relative humidity for 48 hours, the glass surface was ground with dry sandpaper. The results of the compositional analysis showed that the amount of boron decreased from the glass surface to a depth of approximately 1 μm in the samples after the high-temperature and high-humidity constant test. Therefore, the thickness after grinding was 3 μm from the glass surface. After grinding, the relative permittivity and dielectric loss tangent were measured at 25°C and 2.45 GHz using the cavity resonator method. The results are presented below. Figure 2 .

[0162] according to Figure 2 It can be seen that the dielectric loss tangent of samples No. 25 and 26 after grinding became the same as that before the high temperature and high humidity constant test. On the other hand, the dielectric loss tangent of sample No. 7 was the same before and after the high temperature and high humidity constant test, and it was also the same after grinding. As for the relative permittivity, the relative permittivity of samples No. 7, 25, and 26 remained approximately unchanged before and after grinding.

[0163] Finally, for samples No. 7, 25, and 26, under the conditions of 120℃, 85% relative humidity, and a test time of 48 hours, the reflectance and transmittance spectra in the infrared wavelength region were measured using the aforementioned Fourier transform infrared spectrophotometer (FT-IR) before and after the high-temperature and high-humidity constant test, and after the test, when the sample was kept at the annealing point +30℃ for 3 hours and then cooled to room temperature at -3℃ / min. The β-OH value of each sample was calculated based on the transmittance spectra. The reflectance spectrum of sample No. 7 is shown below. Figure 3 (a) The reflectance spectrum of sample No. 25 is shown in... Figure 3 (b) The reflectance spectrum of sample No. 26 is shown in... Figure 3 (c). The transmittance spectra of sample No. 7 are shown in [the diagram]. Figure 4 (a) The transmittance spectrum of sample No. 25 is shown in... Figure 4(b) The transmittance spectrum of sample No. 26 is shown in... Figure 4 (c). The changes in β-OH values ​​of samples No. 7, No. 25, and No. 26 are shown in the figure. Figure 5 .

[0164] according to Figure 3 , 4 It can be seen that for samples No. 25 and 26, no changes were observed in the reflectance and transmittance spectra before and after the high-temperature and high-humidity constant test and after heat treatment. This means that the bonding state, amount, and moisture content of silicon (Si) and oxygen (O), and boron (B) and O atoms in the glass changed, suggesting that the glass structure changed. It should be noted that in Figure 3 In the reflectance spectrum, 900 cm⁻¹ -1 1300~1500cm -1 The nearby peaks represent the stretching vibrations of BO3 and BO4, at 1100 cm⁻¹. -1 The nearby peaks represent the stretching vibrations of the Si-O bonds. Figure 4 In the transmittance spectrum, 3600 cm⁻¹ -1 The nearby peaks represent hydroxyl groups in the glass that form hydrogen bonds with non-crosslinked oxygen.

[0165] For samples No. 7, 25, and 26, the β-OH values ​​were calculated based on the transmittance spectra. The β-OH values ​​of samples No. 25 and 26 were higher after the high-temperature and high-humidity constant test than before the test. Furthermore, if heat treatment was performed after the high-temperature and high-humidity constant test, the β-OH values ​​were lower than after the test. On the other hand, for sample No. 7, the β-OH value remained unchanged in all measurements.

[0166] It should be noted that, Figure 6 (a) shows the relationship between the dielectric loss tangent and the β-OH value at 25°C and 2.45 GHz for sample No.7. Figure 6 (b) shows the relationship between the dielectric loss tangent and the β-OH value at 25°C and 2.45 GHz for sample No. 25. Figure 6 (c) shows the relationship between the dielectric loss tangent and the β-OH value at 25°C and 2.45 GHz for sample No. 26.

[0167] The following is a hypothesis about the mechanism of the change in the tangent of the dielectric loss angle.

[0168] according to Figure 2 Based on the measurements of the relative permittivity and dielectric loss tangent after 3μm surface grinding, it is inferred that the change in dielectric loss tangent in this study was due to the change in the glass surface.

[0169] No foreign matter precipitation was observed in samples No. 25 and 26 after the high temperature and high humidity constant test. According to... Figure 1 The compositional analysis results suggest that during the high temperature and humidity constant test, boron on the glass surface sublimated in the form of H3BO3. Furthermore, it is presumed that during the high temperature and humidity constant test, H3BO3 was removed from the glass surface, resulting in the intrusion of H2O, some of which bonded as hydroxyl groups (-OH). Therefore, the β-OH value, an indicator of moisture content in the glass after the high temperature and humidity constant test, increased. It is also speculated that during heat treatment after the high temperature and humidity constant test, the hydroxyl groups on the glass surface detached as H2O, reducing the number of hydroxyl groups. Therefore, after heat treatment, the β-OH value decreased, and the dielectric loss tangent approached the value before the test (refer to...). Figure 6 ).

[0170] The reasoning that the dielectric loss tangent changes due to variations in the β-OH value, i.e., the water content, is based on the influence of the polarization of hydroxyl groups (-OH) presumably present in the voids of the glass network, and the polarization of water molecules. Generally, hydroxyl groups tend to polarize due to the different electronegativity of their constituent elements (O and H). When an external electromagnetic field is applied, the goal is to orient the polarized hydroxyl groups to follow the electromagnetic field. The dielectric loss tangent is considered to represent the lag in the orientation of polarized molecules when an electromagnetic field is applied. The dielectric loss tangent also varies with the amount of hydroxyl groups; for the same glass composition, the more hydroxyl groups present, the higher the dielectric loss tangent (see reference). Figure 6 ).

[0171] Based on the results of this investigation, it is inferred that sample No. 7, compared with samples No. 25 and 26, has a lower boron content and lower reactivity with moisture, therefore no change in the dielectric loss tangent occurred (refer to...). Figure 6 Therefore, this phenomenon shows that by setting the glass composition to a preferred range, especially by setting the product of the content (mol%) of B2O3-Al2O3 and the content (mol%) of B2O3-(MgO+CaO+SrO+BaO) to 600 or less, and especially 260 or less, the change in the dielectric loss tangent can be effectively suppressed.

[0172] Industrial availability

[0173] The glass of the present invention is suitable as a standard sample for measuring the dielectric properties in the high-frequency domain. In addition, it is also suitable for substrates for printed circuit boards, glass antennas, micro LEDs, glass inserters, and backlights made of various materials such as metal and ceramics that require low dielectric properties.

Claims

1. A type of glass, characterized in that, As a component, it contains, by mole percent, 60–75% SiO2, 0–15% Al2O3, 8–28% B2O3, 0–3% Li2O+Na2O+K2O, and 0–6.10% MgO+CaO+SrO+BaO, and has a relative permittivity of 6 or less at 25°C and 2.45 GHz. After a constant temperature and humidity test of 85℃ and 85% for 1000 hours, the change rate of the dielectric loss tangent at a measurement frequency of 2.45 GHz and a measurement temperature of 25℃ was less than 30%.

2. The glass according to claim 1, characterized in that, After a high-temperature and high-humidity constant test at 120℃ and 85% relative humidity for 12 hours based on JIS-C0096-2001, the change rate of the dielectric loss tangent at a measured frequency of 2.45 GHz and a measured temperature of 25℃ was less than 30%.

3. The glass according to claim 1 or 2, characterized in that, The X-ray intensity of boron, obtained by analyzing the surface from the depth direction after a constant high temperature and humidity test of 120°C and 85% relative humidity for 48 hours based on JIS-C0096-2001, was reduced by 50% to a depth of less than 5 μm, with a reference depth of 15 μm.

4. The glass according to claim 1 or 2, characterized in that, The product of the content of B2O3-Al2O3 (in mole percent) and the content of B2O3-(MgO+CaO+SrO+BaO) in the composition is less than 260.

5. The glass according to claim 1 or 2, characterized in that, It is crystallized glass.

6. The glass according to claim 1 or 2, characterized in that, Standard substances used for measuring dielectric properties.

7. A method for determining dielectric properties, characterized in that, It is a method for determining the dielectric properties of a standard substance, wherein the glass used in determining the standard substance is any one of claims 1 to 6.

8. The method for determining dielectric properties according to claim 6, characterized in that, Before measuring dielectric properties, the standard substance to be measured is heated to a temperature above the annealing point of the glass.

Images