Alkali-free glass and glass sheet

Abstract

The present invention is an alkali-free glass containing, in terms of the mole percentage on the oxide basis, SiO2 57 to 70%, Al2O3 5 to 15%, B2O3 15 to 24%, MgO 0.2 to 10%, CaO 0.1 to 7%, SrO 0.1 to 2.5%, BaO 0 to 10%, ZnO 0 to 0.1%, and the value of formula (A) represented by [Al2O3] / [B2O3] exceeds 0.35 and is 1.4 or less.

Description

[0001] This application is a divisional application of the invention application with application number 202080027679.7, application date of April 7, 2020, and invention title "Alkali-free Glass and Glass Plate". Technical Field

[0002] This invention relates to an alkali-free glass. It also relates to glass plates comprising the aforementioned alkali-free glass, glass substrates for high-frequency devices, panel antennas, window glass, vehicle window glass, and cover glass for touch panels. Background Technology

[0003] Electronic devices include communication equipment such as mobile phones, smartphones, portable information terminals, and Wi-Fi devices, as well as surface acoustic wave (SAW) devices, radar components, and antenna components. In these electronic devices, to achieve larger communication capacity and higher communication speeds, the signal frequency is constantly being increased. The circuit boards used in high-frequency electronic devices generally employ insulating substrates such as resin substrates, ceramic substrates, and glass substrates. In the insulating substrates used in high-frequency devices, to ensure the quality and strength of high-frequency signals, it is necessary to reduce transmission losses based on dielectric loss, conductor loss, and other factors.

[0004] Among these insulating substrates, resin substrates have relatively low rigidity due to their properties. Therefore, resin substrates are difficult to use when rigidity (strength) is required in semiconductor packaging products. Ceramic substrates have the following difficulties: it is difficult to improve the surface smoothness, which easily leads to increased conductor losses caused by conductors formed on the substrate surface. On the other hand, glass substrates have the following characteristics: due to their high rigidity, it is easy to achieve miniaturization and thinning of the package, and the surface smoothness is also excellent, and the substrate itself is easy to enlarge.

[0005] However, while conventional alkali-free glass substrates have shown effectiveness in reducing dielectric loss and transmission loss based on that dielectric loss up to around 20 GHz, the reduction in dielectric loss is limited in regions above that, such as above 30 GHz. Therefore, it is difficult to maintain the quality, strength, and other characteristics of high-frequency signals above 30 GHz in circuit boards using conventional alkali-free glass substrates. On the other hand, quartz glass substrates can also maintain low dielectric loss in regions above 30 GHz, but their coefficient of thermal expansion is too small, resulting in a large difference in the coefficient of thermal expansion between them and other components when used in electronic devices. This becomes a significant factor reducing the practicality of electronic devices.

[0006] Patent Document 1 discloses a glass substrate for high-frequency devices with a dielectric loss tangent of 0.0007 or less at 35 GHz. In the glass substrate for high-frequency devices described in Patent Document 1, by satisfying specified conditions in the amount and ratio of Al2O3 and B2O3, a dielectric loss tangent of 0.0007 or less can be achieved.

[0007] Therefore, it is believed that in order to reduce dielectric loss in high-frequency regions such as above 30 GHz, the higher the B2O3 content, the better.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: International Publication No. 2018 / 051793 Summary of the Invention

[0011] However, increasing the B2O3 content reduces the glass's resistance to reagents. In the manufacturing process of circuit boards for liquid crystal antennas, high-frequency devices, etc., reagent cleaning is performed as a pretreatment for forming wiring layers on the glass substrate. When the glass has low reagent resistance, for example, during acid cleaning, the substrate surface dissolves, damaging its smoothness, which may reduce the adhesion of the film formed on the substrate surface. Furthermore, leachates may adhere to the substrate surface. This could potentially increase conductor losses due to conductors formed on the substrate surface.

[0012] The purpose of this invention is to provide an alkali-free glass that combines low dielectric loss tangent in the high-frequency region with acid resistance.

[0013] The inventors conducted in-depth research and found that the above-mentioned objective can be achieved by adopting the following configuration.

[0014] [1] An alkali-free glass, based on the molar percentage of oxides, contains 57-70% SiO2, 5-15% Al2O3, 15-24% B2O3, 0.2-10% MgO, 0.1-7% CaO, 0.1-2.5% SrO, 0-10% BaO, and 0-0.1% ZnO, with formula (A) being [Al2O3] / [B2O3], wherein the value of the above formula (A) is greater than 0.35 and less than 1.4.

[0015] [2] An alkali-free glass, based on the molar percentage of oxides, contains 57-70% SiO2, 5-15% Al2O3, 15-24% B2O3, 0.1-10% MgO, 0.1-10% CaO, 0.1-10% SrO, 0.1-10% BaO, and 0-0.1% ZnO, with formula (A) being [Al2O3] / [B2O3], wherein the value of the above formula (A) exceeds 0.35 and is less than 1.4.

[0016] [3] According to the alkali-free glass described in [1] or [2] above, wherein formula (B) is [MgO]+[CaO]+[SrO]+[BaO], and the value of formula (B) is 7% to 16%.

[0017] [4] The alkali-free glass according to any one of [1] to [3] above, wherein the value of formula (B) above is 8% to 16%.

[0018] [5] The alkali-free glass according to any one of [1] to [4] above, wherein the formula (C) is [Al2O3]-([MgO]+[CaO]+[SrO]+[BaO]), and the value of the above formula (C) is greater than -3% and less than 2%.

[0019] [6] The alkali-free glass according to any one of [1] to [5] above, wherein the value of the above formula (A) is 0.49 or more.

[0020] [7] An alkali-free glass according to any one of [1] to [5] above, wherein formula (D) is [SrO] / ([MgO]+[CaO]+[SrO]+[BaO]), and the value of formula (D) is 0.64 or more.

[0021] [8] The alkali-free glass according to any one of [1] to [7] above, wherein it contains less than 1 mol% Fe when converted to Fe2O3.

[0022] [9] The alkali-free glass according to any one of [1] to [8] above, wherein the β-OH value of the glass is 0.05 mm. －1 ~1.0mm －1 .

[0023]

[10] The alkali-free glass according to any one of [1] to [9] above, wherein the total content of [Li2O]+[Na2O]+[K2O] is 0 to 0.2 mol%.

[0024]

[11] The alkali-free glass according to any one of [1] to

[10] above, wherein it contains at least one selected from SnO2, Cl and SO3 in total less than 1 mol%.

[0025]

[12] The alkali-free glass according to any one of [1] to

[11] above, wherein it contains at least one of the following selected from Sc2O3, TiO2, ZnO, Ga2O3, GeO2, Y2O3, ZrO2, NB2O5, In2O3, TeO2, HfO2, Ta2O5, WO3, Bi2O3, La2O3, Gd2O3, Yb2O3 and Lu2O3, totaling less than 1 mol%.

[0026]

[13] The alkali-free glass according to any one of [1] to

[12] above, wherein it contains less than 1 mol% of F.

[0027]

[14] The alkali-free glass according to any one of [1] to

[13] above, wherein the dielectric loss tangent at 35 GHz is 0.006 or less.

[0028]

[15] The alkali-free glass according to any one of [1] to

[14] above, wherein the resistivity at 1500°C is 400 Ω·cm or less.

[0029]

[16] The alkali-free glass according to any one of [1] to

[15] above, wherein the resistivity at 1500°C is 300 Ω·cm or less.

[0030]

[17] The alkali-free glass according to any one of [1] to

[16] above, wherein the Young's modulus is 58 GPa or higher.

[0031]

[18] The alkali-free glass according to any one of [1] to

[17] above, wherein the density is 2.58 g / cm³. 3 The average coefficient of thermal expansion for temperatures ranging from 50 to 350°C is 30 × 10⁻⁶. －7 / ℃~40×10 －7 / ℃.

[0032]

[19] The alkali-free glass according to any one of [1] to

[18] above, wherein the glass viscosity is 10. 2 The temperature T2 of dPa·s is 1500~1700℃, and the glass viscosity is 10. 4 The temperature T4, dPa·s, is below 1290℃.

[0033]

[20] The alkali-free glass according to any one of [1] to

[19] above, wherein the glass transition temperature is below 700°C, or the strain point is below 700°C.

[0034]

[21] The alkali-free glass according to any one of [1] to

[20] above has a surface devitrification temperature of 1300°C or below.

[0035]

[22] The alkali-free glass according to any one of [1] to

[21] above, wherein the amount of glass component dissolved per unit surface area when immersed in an aqueous solution containing 6% by weight HNO3 and 5% by weight H2SO4 at 45°C for 170 seconds is 0.025 mg / cm³. 2 the following.

[0036]

[23] A glass plate comprising any one of the above [1] to

[22] alkali-free glass and having a main surface and an end surface, wherein the arithmetic mean roughness Ra of at least one main surface is less than 1.5 nm.

[0037]

[24] According to the glass plate described in

[23] above, at least one side is 900 mm or more and the thickness is 0.7 mm or less.

[0038]

[25] The glass plate described in

[22] or

[23] above is manufactured by float glass or melt glass.

[0039]

[26] A glass substrate for high-frequency devices, comprising any one of the above [1] to

[22] alkali-free glass.

[0040]

[27] A panel antenna comprising the alkali-free glass described in any one of [1] to

[22] above.

[0041]

[28] A window glass comprising any one of the above [1] to

[22] alkali-free glass.

[0042]

[29] A window glass for a vehicle, comprising any one of the above [1] to

[22] alkali-free glass.

[0043]

[30] A cover glass for a touch panel, comprising any one of the above [1] to

[22] alkali-free glass.

[0044] The alkali-free glass of the present invention can reduce dielectric loss of high-frequency signals. Therefore, it is suitable for glass substrates for high-frequency devices. Circuit boards using such glass substrates can reduce transmission loss of high-frequency signals, enabling the provision of practical electronic devices and other high-frequency devices.

[0045] The alkali-free glass of the present invention exhibits excellent acid resistance. Therefore, during acid cleaning of the glass substrate in the manufacturing process of circuit boards for liquid crystal antennas, high-frequency devices, etc., there is no concern that the substrate surface will dissolve, leading to a deterioration in the smoothness of the substrate surface or the adhesion of leachates to the substrate surface. Thus, it is possible to prevent a decrease in the adhesion of the film formed on the substrate surface. Furthermore, it is possible to prevent an increase in conductor losses.

[0046] The alkali-free glass of this invention can reduce transmission loss of radio waves in high-frequency bands and is less prone to damage and breakage. Therefore, it is also suitable for glass products that receive and transmit radio wave signals in high-frequency bands. Attached Figure Description

[0047] Figure 1 This is a cross-sectional schematic diagram illustrating an example of the structure of a circuit board for high-frequency devices.

[0048] Symbol Explanation

[0049] 1: Circuit board

[0050] 2: Glass substrate

[0051] 2a, 2b: Main surfaces

[0052] 3, 4: Wiring layer Detailed Implementation

[0053] The embodiments of the present invention will now be described. It should be noted that in the following description, the numerical range indicated by “~” represents the range of minimum and maximum values ​​for the values ​​listed before and after “~”, respectively. Unless otherwise specified, the content of each component in the alkali-free glass and glass plate represents the molar percentage (mol%) based on oxides. Furthermore, the description of [metal oxide] in formulas (A) to (D), such as [MgO], represents the molar percentage of the metal oxide component, such as magnesium oxide.

[0054] It should be noted that "high frequency" in this specification refers to 10 GHz or higher, preferably greater than 30 GHz, and more preferably 35 GHz or higher.

[0055] The alkali-free glass (hereinafter, sometimes simply referred to as "glass") of this embodiment will be described below.

[0056] If the content of SiO2 as a network forming material is 57 mol% (or less, simply %) or more, it enables good glass forming ability and weather resistance, and suppresses devitrification. The SiO2 content is preferably 58% or more, more preferably 60% or more, and even more preferably 61% or more. Furthermore, if the SiO2 content is 70% or less, it enables good glass solubility. The SiO2 content is preferably 68% or less, more preferably 66% or less, even more preferably 65% ​​or less, particularly preferably 64% or less, and most preferably 63% or less.

[0057] Al2O3 is a component that contributes to improving weather resistance, increasing Young's modulus, suppressing phase separation in glass, and reducing the coefficient of thermal expansion. If the Al2O3 content is 5% or more, the effects of containing Al2O3 are fully achieved. The Al2O3 content is preferably 6% or more, more preferably 7% or more, and even more preferably 8% or more. Furthermore, if the Al2O3 content is 15% or less, the glass exhibits good solubility and other properties. The Al2O3 content is preferably 14% or less, more preferably 13% or less, and even more preferably 12% or less.

[0058] If the B2O3 content is 24% or less, good reagent resistance can be achieved. The B2O3 content is preferably 23% or less, more preferably 22% or less, even more preferably 21% or less, even more preferably 20% or less, particularly preferably 19% or less, and most preferably 18% or less. Furthermore, if the B2O3 content is 15% or more, solubility is improved. Additionally, the dielectric loss tangent in the high-frequency region can be reduced. The B2O3 content is preferably 16% or more, more preferably 17% or more, and even more preferably 17.5% or more.

[0059] MgO is a component that increases Young's modulus without increasing specific gravity. That is, MgO is a component that increases the specific modulus of elasticity, thereby reducing flexural problems, increasing fracture toughness, and thus improving glass strength. Furthermore, MgO is a component that also improves solubility. If the MgO content is 0.1% or more, the effect of containing MgO is obtained, and the coefficient of thermal expansion is prevented from becoming too low. The MgO content is preferably 0.2% or more, more preferably 1% or more, and even more preferably 2% or more. If the MgO content is 10% or less, the rise in devitrification temperature is suppressed. The MgO content is preferably 9% or less, more preferably 8% or less, even more preferably 7% or less, even more preferably 6% or less, even more preferably 5% or less, particularly preferably 4% or less, and most preferably 3% or less.

[0060] CaO is a component that, like MgO, increases the specific elastic modulus second only to MgO among alkaline earth metals without excessively lowering the strain point, and also improves solubility. Furthermore, it is a component that, compared to MgO, does not easily raise the devitrification temperature. If the CaO content is 0.1% or more, the effects of containing CaO are sufficiently obtained. The CaO content is preferably 0.2% or more, more preferably 0.5% or more, further preferably 1% or more, and particularly preferably 2% or more. Additionally, if the CaO content is 10% or less, the average coefficient of thermal expansion is not excessively increased, and the rise in devitrification temperature is suppressed, thus preventing devitrification during glass manufacturing. The CaO content is preferably 8% or less, more preferably 7% or less, further preferably 6% or less, even more preferably 5% or less, further preferably 4% or less, and particularly preferably 3% or less.

[0061] SrO is a component that improves solubility without raising the devitrification temperature of the glass. The effect of containing SrO is fully obtained when the SrO content is 0.1% or more. The SrO content is preferably 0.2% or more, more preferably 0.5% or more, further preferably 1% or more, and particularly preferably 2% or more. If the SrO content is 10% or less, the specific gravity is not excessively increased, and the average coefficient of thermal expansion is also prevented from becoming excessively high. The SrO content is preferably 9% or less, more preferably 8% or less, further preferably 7% or less, even more preferably 6% or less, even more preferably 5% or less, even more preferably 4% or less, particularly preferably 3% or less, and most preferably 2.5% or less.

[0062] BaO is not an essential component, but rather a component that improves solubility without raising the devitrification temperature of the glass. When BaO is present, the aforementioned effects of containing BaO are sufficiently achieved if its content is 0.1% or more, which is therefore preferred. The BaO content is more preferably 0.2% or more, further preferably 1% or more, and particularly preferably 2% or more. However, when a large amount of BaO is present, there is a tendency for the specific gravity to increase, Young's modulus to decrease, the relative permittivity to increase, and the average coefficient of thermal expansion to become excessively large. Therefore, the BaO content is preferably 10% or less, more preferably 8% or less, further preferably 5% or less, and even more preferably 3% or less.

[0063] ZnO is not an essential component, but rather a component that improves reagent resistance. However, when the content of ZnO is high, phase separation becomes more likely, and the devitrification temperature may increase. Therefore, the ZnO content is 0.1% or less. The ZnO content is preferably 0.05% or less, more preferably 0.03% or less, even more preferably 0.01% or less, and particularly preferably substantially absent. In this invention, substantially absent ZnO means, for example, less than 0.01%.

[0064] In this embodiment of the alkali-free glass, when Formula (A) represents the content ratio of [Al2O3] / [B2O3], the value of Formula (A) is greater than 0.35 and less than 1.4. If the value of Formula (A) is within the above range, dielectric loss in high-frequency regions exceeding 30 GHz can be reduced, and the acid resistance of the glass is improved. Furthermore, phase separation is suppressed, resulting in a glass with excellent uniformity. When the value of Formula (A) is less than 0.35, the acid resistance of the glass deteriorates. Additionally, it is difficult to obtain a glass with excellent uniformity due to phase separation. When the value of Formula (A) exceeds 1.4, dielectric loss in high-frequency regions exceeding 30 GHz cannot be reduced. The value of Formula (A) is preferably less than 1.2, more preferably less than 1.0, and even more preferably less than 0.8. The value of Formula (A) is preferably more than 0.40, more preferably more than 0.45, and even more preferably more than 0.49.

[0065] Furthermore, when the value represented by formula (A) is 0.49 or higher, the Young's modulus increases, for example, to 64 GPa or higher, which is further preferred. The value represented by formula (A) is even more preferably 0.52 or higher, even more preferably 0.56 or higher, particularly preferably 0.59 or higher, and most preferably 0.61 or higher.

[0066] In this embodiment of the alkali-free glass, when Formula (B) represents the total content of [MgO] + [CaO] + [SrO] + [BaO], the value represented by Formula (B) is preferably 7% to 16%. If the value represented by Formula (B) is within the above range, the resistivity in the melting temperature region, for example, the resistivity at 1500°C, becomes lower, and the acid resistance of the glass is improved. The alkali-free glass of this embodiment, with its low resistivity in the melting temperature region, can improve the productivity and quality of the alkali-free glass by applying electro-melting during the melting of the glass raw materials. Specifically, when the value represented by Formula (B) is 7% or more, the resistivity in the melting temperature region can be reduced. When the value represented by Formula (B) is 16% or less, the acid resistance of the glass can be improved. In addition, the dielectric loss in the high-frequency region exceeding 30 GHz can be appropriately reduced. The value represented by Formula (B) is more preferably 14% or less, further preferably 13% or less, even more preferably 12% or less, particularly preferably 11% or less, and most preferably 10.5% or less. The value represented by formula (B) is more preferably 8% or more, further preferably 8.5% or more, and even more preferably 9% or more.

[0067] In this embodiment of the alkali-free glass, when the content of formula (C) is represented by [Al2O3]-([MgO]+[CaO]+[SrO]+[BaO]), the value represented by formula (C) is preferably greater than -3% and less than 2%. If the value represented by formula (C) is within the above range, devitrification of the glass can be suppressed, and the acid resistance of the glass can be improved. Specifically, when the value represented by formula (C) is greater than -3%, the acid resistance of the glass is better. When the value represented by formula (C) is less than 2%, the glass becomes less prone to devitrification. The value represented by formula (C) is more preferably 1.5% or less, further preferably 1.0% or less, and particularly preferably 0.5% or less. The value represented by formula (C) is more preferably -2% or more, further preferably -1% or more, and particularly preferably -0.5% or more.

[0068] In this embodiment of the alkali-free glass, when Formula (D) represents the content ratio expressed as [SrO] / ([MgO]+[CaO]+[SrO]+[BaO]), the value of Formula (D) is preferably 0.64 or higher. If the value expressed by Formula (D) is within the above range, the surface devitrification temperature decreases; for example, the surface devitrification temperature becomes 1219°C or lower, and the glass production rate increases. The value of Formula (D) is more preferably 0.7 or higher, further preferably 0.75 or higher, and particularly preferably 0.8 or higher. Furthermore, there is no particular upper limit; for example, 0.95 or lower is preferred.

[0069] To reduce the resistivity in the melting temperature region, such as the resistivity at 1500°C, the alkali-free glass of this embodiment may contain Fe. From the viewpoint of suppressing the reduction in transmittance in the visible area, the Fe content, calculated as Fe₂O₃, is preferably 1 mol% or less, more preferably 0.5 mol% or less, and even more preferably 0.1 mol% or less.

[0070] The β-OH value (mm) of the alkali-free glass in this embodiment －1 The preferred size is 0.05mm. －1 ~1.0mm -1 .

[0071] The β-OH value is an indicator of the moisture content in glass. It is determined by measuring the absorbance of a glass sample for light with wavelengths ranging from 2.75 to 2.95 μm, and the maximum absorbance β is calculated as follows. max It is calculated by dividing by the thickness (mm) of the sample. When the β-OH value is within the above range, the resistivity decreases in the melting temperature range of the glass raw material, such as around 1500°C, making it suitable for melting the glass by electric heating, and resulting in fewer bubble defects in the glass. Specifically, the β-OH value is 0.05 mm. －1 At this temperature, the resistivity decreases in the region where the glass raw material is melted. Additionally, the dielectric loss tangent in the high-frequency region can be appropriately reduced. The β-OH value is 1.0 mm. －1The following conditions can suppress bubble defects in glass. A more preferred β-OH value is 0.8 mm. －1 Hereinafter, 0.6mm is further preferred. －1 The following is particularly preferred: 0.5mm －1 The following is a preferred β-OH value: 0.1 mm. －1 The above is further preferred to be 0.2mm. －1 The above, especially preferred, is 0.3mm. －1 above.

[0072] The alkali-free glass of this embodiment preferably does not contain alkali metal oxides such as Li₂O, Na₂O, and K₂O. In this embodiment, "not containing alkali metal oxides" means that it does not contain any alkali metal oxides except for unavoidable impurities mixed in from raw materials, etc., that is, it is not intentionally contained. However, in order to obtain specific effects, such as lowering the strain point, lowering Tg, lowering the slow cooling point, and lowering the resistivity in the temperature range where the glass raw material is melted, alkali metal oxides may be included in a specified amount.

[0073] Specifically, the total content, expressed as [Li₂O] + [Na₂O] + [K₂O], contains at least 0.2% or less of at least one of Li₂O, Na₂O, and K₂O. More preferably, it is 0.15% or less, further preferably 0.1% or less, even more preferably 0.08% or less, still more preferably 0.05% or less, and most preferably 0.03% or less. Alternatively, the total content, expressed as 0.001% or more of at least one of Li₂O, Na₂O, and K₂O, can be expressed as mol% based on oxides. More preferably, it is 0.003% or more, further preferably 0.005% or more, even more preferably 0.008% or more, still more preferably 0.01% or less, and most preferably 0.02% or more. It should be noted that in this specification, the total content of [Li₂O] + [Na₂O] + [K₂O] is sometimes expressed as R₂O. R represents an alkali metal.

[0074] To improve the clarity of the glass, the alkali-free glass of this embodiment may contain at least one selected from SnO2, Cl, and SO3, preferably in a total content of 1 mol% or less, more preferably 0.5 mol% or less, and even more preferably 0.3 mol% or less. The lower limit is 0% (not containing).

[0075] From the viewpoint of reducing bubble defects in the glass and reducing the dielectric loss tangent in the high-frequency region, the alkali-free glass of this embodiment preferably has a Cl content of 0.5 mol% or less, more preferably 0.4 mol% or less, even more preferably 0.3 mol% or less, even more preferably 0.2 mol% or less, and particularly preferably 0.1 mol% or less. The lower limit is 0% (substantially not contained).

[0076] To improve the acid resistance of the glass, the alkali-free glass of this embodiment may contain at least one trace component selected from Sc2O3, TiO2, ZnO, Ga2O3, GeO2, Y2O3, ZrO2, NB2O5, In2O3, TeO2, HfO2, Ta2O5, WO3, Bi2O3, La2O3, Gd2O3, Yb2O3, and Lu2O3. Excessive content of the trace component reduces the uniformity of the glass and makes it prone to phase separation; therefore, the total content of the trace component is preferably 1 mol% or less. The aforementioned trace component may contain only one type or two or more types.

[0077] To improve the solubility of the glass, lower its strain point, reduce its glass transition temperature, and lower its slow cooling point, the alkali-free glass of this embodiment may contain less than 1 mol% of fluoride (F). When the F content exceeds 1 mol%, there may be more bubble defects in the glass.

[0078] To improve the solubility, clarity, and formability of the glass, and to obtain absorption at specific wavelengths, improve density, hardness, flexural stiffness, and durability, the alkali-free glass of this embodiment may contain one or more of Se2O3, TeO2, Ga2O3, In2O3, GeO2, CdO, BeO, and Bi2O3. The total content of these is preferably 2% or less, more preferably 1% or less, further preferably 0.5% or less, even more preferably 0.3% or less, still more preferably 0.1% or less, particularly preferably 0.05% or less, and most preferably 0.01% or less.

[0079] In order to improve the solubility, clarity, and formability of the glass, and in order to improve the hardness of the glass, such as Young's modulus, the alkali-free glass of this embodiment may contain rare earth oxides and transition metal oxides.

[0080] The alkali-free glass of this embodiment may contain one or more rare earth oxides selected from Sc2O3, Y2O3, La2O3, Ce2O3, Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, DY2O3, Ho2O3, Re2O3, Tm2O3, Yb2O3, and Lu2O3. The total content of these oxides is preferably 2% or less, more preferably 1% or less, further preferably 0.5% or less, even more preferably 0.3% or less, still more preferably 0.1% or less, particularly preferably 0.05% or less, and most preferably 0.01% or less.

[0081] The alkali-free glass of this embodiment may contain one or more of V2O5, Ta2O3, Nb2O5, WO3, MoO3, and HfO2 as transition metal oxides. The total content of these is preferably 2% or less, more preferably 1% or less, further preferably 0.5% or less, even more preferably 0.3% or less, even more preferably 0.1% or less, particularly preferably 0.05% or less, and most preferably 0.01% or less.

[0082] To improve the solubility of the glass, the alkali-free glass of this embodiment may contain ThO2 as an actinide oxide. The content of ThO2 is preferably 2% or less, more preferably 1% or less, further preferably 0.5% or less, even more preferably 0.3% or less, even more preferably 0.1% or less, even more preferably 0.05% or less, particularly preferably 0.01% or less, and most preferably 0.005% or less.

[0083] In this embodiment, the dielectric loss tangent (tanδ) of the alkali-free glass at 35 GHz is preferably 0.006 or less. If the dielectric loss tangent at 35 GHz is 0.006 or less, dielectric loss in high-frequency regions exceeding 30 GHz can be reduced. More preferably, the dielectric loss tangent at 35 GHz is 0.0054 or less, even more preferably 0.005 or less, even more preferably 0.0045 or less, even more preferably 0.004 or less, and particularly preferably 0.003 or less.

[0084] Furthermore, the dielectric loss tangent at 10 GHz is preferably 0.006 or less, more preferably 0.005 or less, even more preferably 0.004 or less, and most preferably 0.003 or less.

[0085] The alkali-free glass of this embodiment preferably has a relative permittivity of 10 or less at 35 GHz. If the relative permittivity at 35 GHz is 10 or less, dielectric loss in the high-frequency region can be reduced. More preferably, the relative permittivity at 35 GHz is 7 or less, even more preferably 6 or less, and particularly preferably 5 or less.

[0086] Furthermore, the relative permittivity at 10 GHz is preferably 5.5 or less, more preferably 5.3 or less, and even more preferably 5 or less.

[0087] Furthermore, when using alkali-free glass as a glass substrate for high-frequency devices, a high Young's modulus is required. A low Young's modulus can lead to defects such as warping, bending, and breakage of the glass substrate after the metal (e.g., Cu) film is deposited during the device manufacturing process. Alkali-free glass with reduced dielectric loss tangent tends to have a lower Young's modulus.

[0088] The Young's modulus of the alkali-free glass in this embodiment is preferably 58 GPa or higher. If the Young's modulus is within the above range, defects such as glass substrate warping, bending, and breakage after the metal film, such as a Cu film, is formed during the manufacturing process of high-frequency devices can be suppressed. More preferably, the Young's modulus is 60 GPa or higher; even more preferably, 62 GPa or higher; even more preferably, 63 GPa or higher; even more preferably, 64 GPa or higher; even more preferably, 65 GPa or higher; particularly preferably, 66 GPa or higher; especially preferably, 67 GPa or higher; and most preferably, 68 GPa or higher.

[0089] From the perspective of suppressing glass deflection, the specific elastic modulus of the alkali-free glass in this embodiment is preferably 23 GPa·cm. 3 / g or higher, more preferably 24 GPa·cm 3 / g or higher, more preferably 25 GPa·cm 3 / g or more. There is no specific upper limit, but a preferred upper limit is 32 GPa·cm. 3 / g or less.

[0090] The alkali-free glass of this embodiment preferably has a density of 2.58 g / cm³. 3 Therefore, the self-weight deflection is reduced, making the handling of large substrates easier. Furthermore, the weight of devices using glass can be reduced. A density of 2.57 g / cm³ is more preferable. 3 The following is a further preferred value: 2.56 g / cm³ 3 It should be noted that a large substrate refers to, for example, a substrate with at least one side being 900 mm or more.

[0091] In this embodiment, the alkali-free glass preferably has an average coefficient of thermal expansion of 30 × 10⁻⁶ at temperatures between 50 and 350°C. －7 / ℃ or higher. Therefore, when manufacturing a glass substrate, it is possible to prevent the difference in expansion rates between the metal film formed on the glass substrate and the substrate from becoming too large and causing it to break.

[0092] The average coefficient of thermal expansion between 50 and 350°C is more preferably 33 × 10⁻⁶. －7 / ℃ or higher, more preferably 35×10 －7 / ℃ or higher, more preferably 36×10 －7 Above / ℃, especially preferably 37×10 －7 Above / ℃, the optimal value is 38×10. －7 / ℃ or above.

[0093] On the other hand, from the viewpoint of suppressing glass breakage in the manufacturing process of products such as high-frequency devices, the average coefficient of thermal expansion between 50 and 350°C is preferably 43 × 10⁻⁶. －7 / ℃ below.

[0094] The average coefficient of thermal expansion between 50 and 350°C is more preferably 42 × 10⁻⁶. －7 Below / ℃, it is further preferred to be 41.5×10 －7 Below / ℃, more preferably 41×10 －7 Below / ℃, 40.5×10 is further preferred. －7 Below / ℃, 40.3×10 is particularly preferred. －7 Below / ℃, the optimal value is 40×10. －7 / ℃ below.

[0095] In this embodiment, the alkali-free glass preferably has a glass viscosity of 10. 2 The temperature T2 (dPa·s) is 1700°C or lower. By keeping T2 below 1700°C, the glass exhibits excellent solubility, reducing the burden on manufacturing equipment. For example, it can extend the lifespan of equipment such as glass melting furnaces and improve productivity. Furthermore, it can reduce defects from the furnace, such as agglomeration defects and Zr defects. T2 is more preferably 1680°C or lower, and even more preferably 1670°C or lower. T2 is preferably 1500°C or higher.

[0096] In this embodiment, the alkali-free glass preferably has a glass viscosity of 10. 4 The temperature T4, measured in dPa·s, is 1290°C or lower. This results in excellent glass formability. Furthermore, by lowering the glass forming temperature, volatiles in the surrounding atmosphere can be reduced, thereby minimizing glass defects. Glass can be formed at lower temperatures, thus reducing the burden on manufacturing equipment. For example, the lifespan of equipment such as glass-forming furnaces can be extended, increasing productivity. T4 is more preferably 1280°C or lower. However, the lower limit is not particularly limited; for example, 1050°C or higher is preferred.

[0097] T2 and T4 can be viscosed using a rotational viscometer according to the method specified in ASTM C 965-96, and are used as 10... 2 d·Pa·s or 10 4 The temperature at d·Pa·s is used to determine this. It should be noted that in the embodiments described later, NBS710 and NIST717a are used as reference samples for device calibration.

[0098] The glass transition temperature of the alkali-free glass in this embodiment is preferably 700°C or lower. Therefore, it is not necessary to increase the temperature of the slow cooling device, and the reduction in the lifespan of the slow cooling device can be suppressed. The glass transition temperature is more preferably 680°C or lower, and even more preferably 670°C or lower. The glass transition temperature is preferably 600°C or higher. Therefore, deformation and shrinkage (thermal shrinkage) of the glass plate during high-temperature treatment in the high-frequency device manufacturing process can be suppressed. The glass transition temperature is more preferably 620°C or higher, and particularly preferably 630°C or higher.

[0099] Furthermore, the lower the strain point of the alkali-free glass in this embodiment, the better its formability. The strain point is preferably below 700°C, more preferably below 670°C, and even more preferably below 660°C. The lower limit of the strain point is not particularly limited, but is preferably above 550°C for example.

[0100] The alkali-free glass of this embodiment preferably has a surface devitrification temperature of 1300°C or lower. This results in excellent glass formability. It suppresses the formation of crystals within the glass during forming, thus preventing a decrease in transmittance. Furthermore, it reduces the burden on manufacturing equipment. For example, it extends the lifespan of equipment such as floating polishing furnaces used for glass forming, thereby increasing productivity.

[0101] The surface devitrification temperature is further preferably below 1295℃, 1290℃, 1285℃, 1280℃, 1275℃, 1270℃, 1265℃, 1260℃, 1255℃, 1250℃, 1245℃, 1240℃, 1235℃, 1230℃, 1225℃, 1220℃, 1215℃, 1210℃, 1205℃, and 1200℃. Furthermore, the lower limit is not particularly limited; for example, it is preferably above 1000℃.

[0102] The surface devitrification temperature in this embodiment can be determined as follows: Crushed glass particles are placed in a platinum dish and heat-treated in an electric furnace at a controlled temperature for 17 hours. After heat treatment, the highest temperature at which crystals precipitate on the glass surface and the lowest temperature at which no crystals precipitate are observed using an optical microscope, and their average value is taken as the surface devitrification temperature.

[0103] The alkali-free glass of this embodiment preferably exhibits a glass component leaching rate of 0.025 mg / cm³ per unit surface area when immersed in an aqueous solution containing 6 wt% HNO3 and 5 wt% H2SO4 at 45°C for 170 seconds. 2 The following applies if the leaching amount of the glass component is 0.025 mg / cm³. 2 Below this value, it exhibits good acid resistance. A more preferable leaching amount for the glass component is 0.020 mg / cm³. 2The fewer the better.

[0104] If the B2O3 content of alkali-free glass is increased, when the glass raw material in the melting tank is heated and melted by a burner or other means, a greater amount of B2O3 will volatilize during the melting of the glass raw material, resulting in lower productivity.

[0105] On the other hand, electro-melting, in which the glass raw material is melted by directly passing an electric current through the electrodes in the melting tank and causing Joule heating, can suppress the volatilization of B2O3 by forming a cold top layer on the green body of the molten glass (Japanese Patent Application Publication No. 5-163024).

[0106] However, alkali-free glass with a reduced dielectric loss tangent tends to have a higher resistivity in the melting temperature region. When the resistivity in the melting temperature region is high, the difference between the resistivity and the resistivity of the furnace material constituting the main body of the melting tank decreases, and sometimes current even flows to the furnace material forming the walls of the melting tank. When current flows to the furnace material, it can cause problems such as hindering the melting of the glass raw materials, eroding the furnace material, increasing power consumption, and increasing manufacturing costs (International Publication No. 2019 / 004434). Furthermore, when the furnace material is energized, it is damaged and mixed into the glass, potentially leading to the contamination of foreign matter into the glass products.

[0107] In view of the above, the alkali-free glass of this embodiment preferably has a resistivity of 400 Ω·cm or less at 1500°C. If the resistivity at 1500°C is within the above range, it can be melted by heating with electricity during glass manufacturing. More preferably, the resistivity at 1500°C is 300 Ω·cm or less, even more preferably 250 Ω·cm or less, and even more preferably 200 Ω·cm or less. Furthermore, the lower limit is not particularly limited, but is 10 Ω·cm or more.

[0108] The haze value of the 1mm thick glass substrate made of alkali-free glass in this embodiment is preferably 1.0% or less. This results in high glass uniformity; for example, when acid cleaning the glass substrate, localized unevenness on the substrate surface can be appropriately prevented. This reduces transmission loss of high-frequency signals. More preferably, the haze value of the 1mm thick glass substrate made of alkali-free glass in this embodiment is 0.8% or less, more preferably 0.5% or less, and most preferably 0.4% or less; the lower the better.

[0109] The alkali-free glass of this embodiment is suitable for glass substrates for high-frequency devices, panel antennas, window glass, vehicle window glass, and cover glass for touch panels due to the above-mentioned characteristics.

[0110] Figure 1 This is a cross-sectional view showing an example of the structure of a circuit board for high-frequency devices. Figure 1The circuit board 1 shown includes an insulating glass substrate 2, a first wiring layer 3 formed on a first main surface 2a of the glass substrate 2, and a second wiring layer 4 formed on a second main surface 2b of the glass substrate 2. The first wiring layer 3 and the second wiring layer 4 form microstrip lines as an example of transmission lines. The first wiring layer 3 constitutes signal wiring, and the second wiring layer 4 constitutes grounding. However, the structure of the first wiring layer 3 and the second wiring layer 4 is not limited to this. Furthermore, the wiring layers may be formed only on one main surface of the glass substrate 2.

[0111] The first wiring layer 3 and the second wiring layer 4 are layers formed of conductors, with a thickness typically ranging from 0.1 to 50 μm. The conductors forming the first wiring layer 3 and the second wiring layer 4 are not particularly limited; for example, metals such as steel, gold, silver, aluminum, titanium, chromium, molybdenum, tungsten, platinum, and nickel, alloys containing at least one of these metals, and metal compounds can be used. The structure of the first wiring layer 3 and the second wiring layer 4 is not limited to a single layer; it can also have a multi-layer structure, such as a stacked structure of titanium and copper layers. The method of forming the first wiring layer 3 and the second wiring layer 4 is not particularly limited; for example, various known forming methods such as printing with conductor paste, impregnation, plating, vapor deposition, and sputtering can be used.

[0112] If a glass substrate containing the alkali-free glass of this embodiment is used as the glass substrate 2, the dielectric loss tangent (tanδ) at 35 GHz is 0.006 or less. The relative permittivity of the glass substrate 2 at 35 GHz is preferably 10 or less. By making the dielectric loss tangent of the glass substrate 2 at 35 GHz 0.006 or less, dielectric loss in high-frequency regions exceeding 30 GHz can be reduced. Making the relative permittivity of the glass substrate 2 at 35 GHz 10 or less also reduces dielectric loss in high-frequency regions. The dielectric loss tangent of the glass substrate 2 at 35 GHz is more preferably 0.0054 or less, further preferably 0.005 or less, even more preferably 0.0045 or less, further preferably 0.004 or less, and particularly preferably 0.003 or less. The relative permittivity of the glass substrate 2 at 35 GHz is more preferably 7 or less, further preferably 6 or less, and particularly preferably 5 or less.

[0113] Furthermore, the glass substrate 2 has main surfaces 2a, 2b and end faces. For at least one main surface of the glass substrate 2 forming the first wiring layer 3 and the second wiring layer 4, the arithmetic mean roughness Ra is preferably 1.5 nm or less, and more preferably the arithmetic mean roughness Ra of both main surfaces is 1.5 nm or less. Therefore, even in the case of skin effect occurring in the first wiring layer 3 and the second wiring layer 4 in high-frequency regions exceeding 30 GHz, the skin resistance of the first wiring layer 3 and the second wiring layer 4 can be reduced, thereby reducing conductor losses. The arithmetic mean roughness Ra of the main surfaces 2a, 2b of the glass substrate 2 is more preferably 1.0 nm or less, and even more preferably 0.5 nm or less. The main surface of the glass substrate 2 refers to the surface forming the wiring layer. When a wiring layer is formed on one main surface, it is sufficient that the value of the arithmetic mean roughness Ra of that main surface is 1.5 nm or less. It should be noted that the surface roughness Ra in this specification refers to a value based on JIS B0601 (2001).

[0114] The surface roughness of the main surfaces 2a and 2b of the glass substrate 2 can be achieved as needed through surface polishing or other treatments. These polishing treatments can include, for example, polishing using abrasives and pads primarily composed of cerium oxide or colloidal silica; polishing using abrasive slurries and pads containing abrasives and acidic or alkaline dispersion media; or polishing using acidic or alkaline etching solutions. These polishing treatments can be applied depending on the surface roughness of the glass substrate 2 blank; for example, pre-polishing and fine polishing can be combined. Furthermore, to prevent cracking, fissures, and notches in the glass substrate 2 caused by the end faces during the manufacturing process, the end faces of the glass substrate 2 are preferably chamfered. The chamfer shape can be any of C-bevel, R-bevel, or micro-bevel.

[0115] By using such a glass substrate 2, the transmission loss of the circuit board 1 at 35 GHz can be reduced, specifically, to below 1 dB / cm. Therefore, in order to maintain the quality, strength, and other characteristics of high-frequency signals, especially high-frequency signals exceeding 30 GHz and even higher than 35 GHz, a glass substrate 2 and a circuit board 1 suitable for processing such high-frequency signals can be provided. That is, the characteristics and quality of high-frequency devices processing such high-frequency signals can be improved. The transmission loss of the circuit board 1 at 35 GHz is more preferably below 0.5 dB / cm.

[0116] The shape of the glass plate comprising the alkali-free glass of this embodiment is not particularly limited, but the thickness is preferably 0.7 mm or less. If the glass plate thickness is 0.7 mm or less, when used as a glass substrate for high-frequency devices, it enables the thinning and miniaturization of high-frequency devices, as well as improved production efficiency. Furthermore, the increased ultraviolet transmittance allows for the use of ultraviolet-curing materials in the device manufacturing process, improving manufacturability. The glass plate thickness is more preferably 0.6 mm or less, further preferably 0.5 mm or less, even more preferably 0.4 mm or less, even more preferably 0.3 mm or less, further preferably 0.2 mm or less, and particularly preferably 0.1 mm or less. The lower limit is approximately 0.01 mm.

[0117] When the glass plate is manufactured into a large substrate, at least one side is preferably 900 mm or more, more preferably 1000 mm or more. There is no particular upper limit, and typically one side is 4000 mm or less. Furthermore, the glass plate is preferably rectangular.

[0118] Next, the manufacturing method of a glass sheet containing alkali-free glass will be described. The manufacturing process of the glass sheet includes a melting process in which glass raw materials are heated to obtain molten glass, a refining process in which air bubbles are removed from the molten glass, a forming process in which the molten glass is formed into a sheet shape to obtain a glass ribbon, and a slow cooling process in which the glass ribbon is slowly cooled to room temperature. Alternatively, a method can be used to manufacture a glass sheet by forming the molten glass into a block, slow cooling it, and then cutting and grinding it.

[0119] The melting process involves preparing raw materials in a manner that forms the composition of the target glass. The raw materials are continuously fed into a melting furnace and preferably heated to approximately 1450°C to 1750°C to obtain molten glass. In this embodiment, the alkali-free glass has a low resistivity in the temperature range where the glass raw materials are melted, for example, around 1500°C. Therefore, an electric melting furnace is preferably used as the melting furnace, and the glass is melted by electric heating. However, both electric heating and burner-based heating can be used concurrently.

[0120] Raw materials can include oxides, carbonates, nitrates, hydroxides, chlorides, and other halides. In melting and refining processes where molten glass comes into contact with platinum, tiny platinum particles can sometimes dissolve in the molten glass and become foreign matter in the resulting glass sheet. However, the use of nitrate raw materials can prevent the formation of platinum foreign matter.

[0121] As nitrates, strontium nitrate, barium nitrate, magnesium nitrate, and calcium nitrate can be used. Strontium nitrate is preferred. The raw material particle size can be appropriately varied, ranging from large particles of several hundred μm that do not produce melting residue to small particles of several μm that do not scatter during transport and do not aggregate in the form of secondary particles. Granulated materials can also be used. To prevent raw material scattering, the moisture content of the raw material can be appropriately adjusted. β-OH value, redox degree of Fe (redox [Fe]... 2+ / (Fe 2+ +Fe 3+ The melting conditions of the )]) can also be adjusted appropriately.

[0122] The next clarification step is to remove bubbles from the molten glass obtained from the above-mentioned melting step. As a clarification step, a degassing method based on reduced pressure can be used, or degassing can be performed at a temperature higher than the melting temperature of the raw material. Furthermore, SO3 or SnO2 can be used as clarifying agents. As an SO3 source, sulfates selected from at least one element chosen from Al, Na, K, Mg, Ca, Sr, and Ba are preferred, and sulfates of alkaline earth metals are more preferred. Among these, CaSO4·2H2O, SrSO4, and BaSO4 have a significant effect on increasing bubble size and are therefore particularly preferred.

[0123] As a clarifying agent in the degassing process based on reduced pressure, halogens such as Cl or F are preferred. As a Cl source, chlorides selected from at least one element chosen from Al, Mg, Ca, Sr, and Ba are preferred, and chlorides of alkaline earth metals are more preferred. SrCl₂·6H₂O and BaCl₂·2H₂O are particularly preferred because they significantly increase bubble size and have low deliquescence. As a F source, fluorides selected from at least one element chosen from Al, Na, K, Mg, Ca, Sr, and Ba are preferred, and fluorides of alkaline earth metals are more preferred. CaF₂ is further preferred because it significantly increases the solubility of the glass raw material.

[0124] Tin compounds, represented by SnO2, generate O2 gas in molten glass. In molten glass, SnO2 is reduced to SnO at temperatures above 1450°C, generating O2 gas, which promotes bubble growth. During glass sheet manufacturing, the glass raw material is heated to approximately 1450–1750°C to melt it, thus allowing bubbles in the molten glass to grow more effectively. When SnO2 is used as a clarifying agent, it is preferable to prepare the raw material in a manner where it contains at least 0.01% tin compounds (based on SnO2 conversion) relative to 100% of the total amount of the master composition. A SnO2 content of 0.01% or more provides a clarifying effect during the melting of the glass raw material; therefore, 0.05% or more is preferred, and 0.10% or more is even more preferred. If the SnO2 content is 0.3% or less, the coloration and devitrification of the glass are suppressed, which is also preferable. The content of tin compounds in the glass is more preferably 0.25% or less, more preferably 0.2% or less, and particularly preferably 0.15% or less, relative to 100% of the total composition of the glass matrix when converted to SnO2.

[0125] The next forming process involves shaping the molten glass, after the air bubbles have been removed in the clarification process, into a sheet to obtain a glass ribbon. As the forming process, known methods for shaping glass into sheets can be employed, such as the float glass method (where molten glass is poured onto a molten metal like tin to form a sheet), the overflow-downflow method (melting method) (where molten glass flows down from a trough), and the slit-downflow method (where molten glass flows down through a slit). Among these, the float glass method or the melting method is preferred from the perspective of no grinding and minimal grinding.

[0126] Next, the slow cooling process involves cooling the glass ribbon obtained from the above forming process under controlled cooling conditions until it reaches room temperature. As a slow cooling process, the glass ribbon is cooled to room temperature under specified conditions. After the slow-cooled glass ribbon is cut, a glass sheet is obtained.

[0127] If the cooling rate R in the slow cooling process is too high, residual strain is likely to remain in the cooled glass. Furthermore, the equivalent cooling rate, which reflects the hypothetical temperature, becomes too high, resulting in an inability to reduce glass shrinkage. Therefore, it is preferable to set R to an equivalent cooling rate of 800°C / min or less. More preferably, the equivalent cooling rate is 400°C / min or less, even more preferably 100°C / min or less, and particularly preferably 50°C / min or less. On the other hand, if the cooling rate is too low, the required process time becomes too long, leading to low productivity. Therefore, it is preferable to set it to 0.1°C / min or more, more preferably 0.5°C / min or more, and even more preferably 1°C / min or more.

[0128] The definition and evaluation method of the equivalent cooling rate are described below. Glass samples were prepared by processing the glass, which was the constituent material, into cubes of 10 mm × 10 mm × 0.3–2.0 mm. The glass samples were then held at +1700°C for 5 minutes using an infrared heating furnace, after which they were cooled to room temperature (25°C). Multiple glass samples were then prepared under conditions where the cooling rate was varied from 10°C / min to 1000°C / min.

[0129] The refractive index n of the d-line (wavelength 587.6 nm) of multiple glass samples was measured using a precision refractive index measuring device (e.g., Shimadzu KPR2000). d The determination can be done using the V-block method or the minimum deflection angle method. This is achieved by obtaining n... d n is obtained by plotting the logarithm of the cooling rate mentioned above. d The standard curve relative to the aforementioned cooling rate.

[0130] Next, using the above-mentioned measurement method, the n of glass of the same composition manufactured through processes such as melting, forming, and cooling was measured. d The measurement was performed. The value of n was determined using the aforementioned standard curve. d The corresponding cooling rate (referred to as the equivalent cooling rate in this embodiment).

[0131] This invention is not limited to the embodiments described above. Modifications and improvements are permitted within the scope of achieving the objectives of this invention. For example, when manufacturing the glass plate of this embodiment, a pressure forming method that directly shapes molten glass into a plate shape can be used to form the glass into a plate shape.

[0132] In addition to the manufacturing method using a refractory melting tank, when manufacturing the glass plate of this embodiment, a platinum or platinum-based alloy crucible (hereinafter referred to as a platinum crucible) can also be used in the melting tank or refining tank. When using a platinum crucible, the melting process prepares raw materials in a manner that constitutes the composition of the obtained glass plate. The platinum crucible containing the raw materials is heated in an electric furnace, preferably to about 1450°C to 1700°C. Molten glass is obtained by stirring with a platinum stirrer for 1 to 3 hours.

[0133] In the forming process of manufacturing glass plates using platinum crucibles, molten glass is poured onto, for example, a carbon plate or a mold frame to form a plate or block. Typically, the slow cooling process involves maintaining the glass at a temperature of approximately Tg+50°C, then cooling it to near the strain point at a rate of approximately 1–10°C / min, followed by cooling to room temperature at a rate that leaves no residual strain. After being cut into a specified shape and ground, a glass plate is obtained. Alternatively, the cut glass plate can be heated to, for example, approximately Tg+50°C and then slowly cooled to room temperature at a specified cooling rate. This allows for adjustment of the glass's equivalent cooling temperature.

[0134] The circuit board 1 using the alkali-free glass as the glass substrate 2 of this embodiment is suitable for high-frequency devices that process high-frequency signals, especially high-frequency signals exceeding 30 GHz and even higher than 35 GHz, and can reduce the transmission loss of such high-frequency signals, thereby improving the quality, strength, and other characteristics of high-frequency signals. The circuit board 1 using the alkali-free glass as the glass substrate 2 of this embodiment is suitable for high-frequency devices (electronic devices) such as semiconductor devices used in communication devices such as mobile phones, smartphones, portable information terminals, and Wi-Fi devices, surface acoustic wave (SAW) devices, radar components such as radar transceivers, and antenna components such as liquid crystal antennas and panel antennas.

[0135] That is, in addition to the glass substrate for high-frequency devices that includes the alkali-free glass of this embodiment, the present invention also relates to a panel-type antenna that includes the alkali-free glass of this embodiment.

[0136] Furthermore, to reduce transmission loss of high-frequency signals, the alkali-free glass of this embodiment can also be appropriately used in other products. That is, the present invention also relates to window glass, vehicle window glass, and cover glass for touch panels that include the above-described alkali-free glass.

[0137] Glass panels containing alkali-free glass are suitable for window glass, vehicle window glass, and touch panel cover glass because they can stabilize high-frequency radio waves for signal transmission and reception and are less prone to damage and breakage. For vehicle window glass, it is even more preferable for applications such as autonomous driving vehicle window glass.

[0138] Example

[0139] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. It should be noted that Examples 1 to 43 and Examples 49 to 61 are examples, and Examples 44 to 48 are comparative examples.

[0140] [Examples 1 to 61]

[0141] Prepare a glass plate with the composition (expressed as mol% based on oxides) shown in Tables 1-5, 11, and 12, a thickness of 1.0 mm, a shape of 50 × 50 mm, and an arithmetic mean roughness Ra of 1.0 nm on the main surface. The glass plate is produced by a melting method using a platinum crucible. Raw materials such as silica sand are mixed in a batch of 1 kg to obtain glass with the composition shown in Tables 1-5, 11, and 12. The raw materials are placed in a platinum crucible and heated in an electric furnace at 1650 °C for 3 hours to produce molten glass. During melting, a platinum stirrer is inserted into the platinum crucible and stirred for 1 hour to homogenize the glass. The molten glass is poured onto a carbon plate, shaped into a plate, and then placed in an electric furnace at approximately Tg + 50 °C and held for 1 hour. The furnace is cooled to Tg - 100 °C at a cooling rate of 1 °C / min, after which the glass is allowed to cool to room temperature. Subsequently, the glass is shaped into a plate through cutting and grinding processes, resulting in a glass plate.

[0142] For the glass plates of Examples 1-48, the average coefficient of thermal expansion (50-350°C), density, glass transition temperature, Young's modulus, specific modulus of elasticity, T2, T4, β-OH value, relative permittivity at 10 GHz or 35 GHz, dielectric loss tangent at 10 GHz or 35 GHz, surface devitrification temperature, acid resistance, haze value, and resistivity at 1500°C are shown in Tables 6-12. It should be noted that the haze value is an indicator of phase separation in the glass. Additionally, blank columns in the tables indicate that measurements were not taken.

[0143] The methods for determining each property are shown below.

[0144] (density)

[0145] The density of a 20g glass block without air bubbles was determined using the Archimedes method.

[0146] (Average coefficient of thermal expansion)

[0147] The determination was performed using a differential thermal dilatometer according to the method specified in JIS R3102 (1995). The measurement temperature range was 50–350 °C, and the units were expressed as ppm / °C or ×10⁻¹⁰. －7 / ℃.

[0148] (Glass transition temperature)

[0149] The determination was performed using the thermal expansion method as specified in JIS R3103-3 (2001).

[0150] (Young's modulus)

[0151] The ultrasonic pulse method was used to measure the thickness of glass from 0.5 to 10 mm according to the method specified in JIS Z2280 (1993). The unit is expressed as GPa.

[0152] (Specific elastic modulus)

[0153] The specific elastic modulus (GPa·cm) is calculated by dividing the Young's modulus determined by the method described above by the density determined using the same method. 3 / g).

[0154] (T2)

[0155] Viscosity was determined using a rotational viscometer according to the method specified in ASTM C 965-96, and the measured viscosity was 10. 2 The temperature T2 (°C) at d·Pa·s.

[0156] (T4)

[0157] Viscosity was determined using a rotational viscometer according to the method specified in ASTM C 965-96, and the measured viscosity was 10. 4 The temperature T4 (°C) at d·Pa·s.

[0158] (Relative permittivity, dielectric loss tangent)

[0159] The measurements were performed using a cavity resonator and a vector network analyzer, following the method specified in JLS R1641 (2007). The measured frequency was the air resonance frequency of the cavity resonator, i.e., 10 GHz or 35 GHz.

[0160] (Surface devitrification temperature)

[0161] The glass was crushed and classified using a test sieve with a particle size ranging from 2 to 4 mm. The resulting glass fragments were ultrasonically cleaned in isopropanol for 5 minutes, rinsed with deionized water, dried, and placed in a platinum dish. The mixture was then heat-treated in an electric furnace at a controlled temperature for 17 hours. The heat treatment temperature was set at 10°C intervals.

[0162] After heat treatment, the glass was removed from the platinum dish and observed using an optical microscope at the highest temperature at which crystals precipitated on the glass surface and the lowest temperature at which no crystals precipitated.

[0163] The highest temperature at which crystals precipitate on the glass surface and the lowest temperature at which no crystals precipitate are each measured once. (In cases where it is difficult to determine whether crystal precipitation has occurred, measurements may be taken twice.)

[0164] The average value of the highest temperature at which crystals precipitate on the glass surface and the lowest temperature at which crystals do not precipitate is used as the surface devitrification temperature.

[0165] (Acid resistance)

[0166] The glass sample was immersed in an acidic aqueous solution (6% HNO3 + 5% H2SO4, 45°C) for 170 seconds, and the leaching amount of glass components per unit surface area (mg / cm²) was evaluated. 2 If the leaching amount of the glass component is 0.02 mg / cm³ 2 The following have good acid resistance.

[0167] (β-OH value)

[0168] The absorbance of the glass sample for light with wavelengths of 2.75–2.95 μm was measured, and the maximum absorbance β was calculated. max The β-OH value is obtained by dividing by the thickness (mm) of the sample.

[0169] (Resistivity at 1500℃)

[0170] The resistivity of molten glass in the temperature range of 1350–1700 °C was measured. The molten glass was obtained by mixing the components in a predetermined manner and melting them in a platinum crucible at 1650 °C. During the melting process, the glass was stirred using a platinum stirrer to ensure homogeneity. Next, the resistivity was measured while the molten glass was maintained at 1500 °C using the method described in the following literature.

[0171] "Method for determining the conductivity of ionic melts, Yoshio Ota, Mitsuru Miyanaga, Kenji Morinaga, and Yorimitsu Yanagi, Journal of the Japan Society for Metals, Vol. 45, No. 10 (1981), pp. 1036-1043"

[0172] (Haze value)

[0173] The haze value of the glass was measured using a haze meter (manufacturer: Suga Testing Equipment Co., Ltd., model: HZ-V3 Hazemeter). The haze value was measured using a glass plate with a thickness of 1 mm and mirror-polished on both sides. A haze value of 35% or less was considered acceptable.

[0174] [Table 1]

[0175] Table 1

[0176] <![CDATA[SiO2]]> 64.0 63.5 63.9 61.0 61.9 63.3 63.0 63.5 63.3 63.5 <![CDATA[Al2O3]]> 9.0 9.5 9.0 9.0 8.0 8.5 9.5 9.5 9.5 9.5 <![CDATA[B2O3]]> 18.5 18.5 19.0 21.9 19.0 19.5 18.5 18.5 17.5 16.5 MgO 4.0 2.5 2.5 4.0 4.0 2.5 3.5 3.0 3.0 3.0 CaO 3.5 3.5 3.5 3.0 2.0 3.5 3.5 3.5 3.5 4.0 SrO 0.8 2.3 1.8 0.8 1.0 2.3 1.8 1.8 2.8 3.3 BaO 0.2 0.2 0.2 0.2 4.0 0.2 0.2 0.2 0.2 0.2 ZnO 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 <![CDATA[Na2O]]> 0.0 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.2 0.0 <![CDATA[K2O]]> 0.0 0.0 0.0 0.1 0.0 0.1 0.0 0.0 0.0 0.0 <![CDATA[Fe2O3]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 MgO + CaO + SrO + BaO 8.5 8.5 8.0 8.0 11.0 8.5 9.0 8.5 9.5 10.5 <![CDATA[R2O]]> 0.0 0.0 0.1 0.1 0.0 0.2 0.0 0.0 0.2 0.0 <![CDATA[Al2O3 / B2O3]]> 0.49 0.51 0.47 0.43 0.42 0.44 0.51 0.51 0.54 0.58 <![CDATA[Al2O3-(MgO+CaO+SrO+BaO)]]> 0.50 1.00 1.00 1.00 -3.00 0.00 0.50 1.00 0.00 -1.00 SrO / (MgO+CaO+SrO+BaO) 0.09 0.27 0.23 0.10 0.09 0.27 0.20 0.21 0.29 0.31

[0177] [Table 2]

[0178] Table 2

[0179] <![CDATA[SiO2]]> 63.5 64.0 64.5 62.0 62.0 62.5 62.5 62.0 62.0 63.5 <![CDATA[Al2O3]]> 9.5 10.0 9.5 11.0 11.0 11.0 11.0 11.0 11.0 8.5 <![CDATA[B2O3]]> 15.5 17.0 17.0 17.0 17.0 17.0 17.0 17.0 17.0 20.0 MgO 3.5 1.0 1.0 3.0 3.0 3.0 3.0 4.0 5.0 6.0 CaO 4.5 6.0 6.0 5.6 5.9 5.4 6.1 4.9 3.9 1.0 SrO 3.3 2.0 2.0 0.2 0.2 0.2 0.2 0.2 0.2 0.8 BaO 0.2 0.0 0.0 1.2 0.9 0.9 0.2 0.9 0.9 0.2 ZnO 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Na2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[K2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Fe2O3]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 MgO + CaO + SrO + BaO 11.5 9.0 9.0 10.0 10.0 9.5 9.5 10.0 10.0 8.0 <![CDATA[R2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Al2O3 / B2O3]]> 0.61 0.59 0.56 0.65 0.65 0.65 0.65 0.65 0.65 0.43 <![CDATA[Al2O3-(MgO+CaO+SrO+BaO)]]> -2.00 1.00 0.50 1.00 1.00 1.50 1.50 1.00 1.00 0.50 SrO / (MgO+CaO+SrO+BaO) 0.29 0.22 0.22 0.02 0.02 0.02 0.02 0.02 0.02 0.10

[0180] [Table 3]

[0181] Table 3

[0182] <![CDATA[SiO2]]> 64.0 63.0 63.2 63.4 63.6 62.9 62.4 63.0 62.5 61.9 <![CDATA[Al2O3]]> 9.5 10.0 8.5 8.3 8.1 8.3 8.3 8.5 8.5 8.5 <![CDATA[B2O3]]> 17.0 17.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 21.1 MgO 8.0 8.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 0.2 CaO 0.5 1.0 0.3 0.3 0.3 0.8 1.3 0.2 0.2 0.2 SrO 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.2 0.2 7.0 BaO 0.2 0.2 0.2 0.2 0.2 0.2 0.2 1.1 1.6 1.1 ZnO 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Na2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[K2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Fe2O3]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 MgO + CaO + SrO + BaO 9.5 10.0 8.3 8.3 8.3 8.8 9.3 8.5 9.0 8.5 <![CDATA[R2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Al2O3 / B2O3]]> 0.56 0.59 0.43 0.42 0.41 0.42 0.42 0.43 0.43 0.40 <![CDATA[Al2O3-(MgO+CaO+SrO+BaO)]]> .0.00 0.00 0.20 0.00 -0.20 -0.50 -1.00 0.00 -0.50 0.00 SrO / (MgO+CaO+SrO+BaO) 0.08 0.08 0.10 0.10 0.10 0.09 0.09 0.02 0.02 0.82

[0183] [Table 4]

[0184] Table 4

[0185] <![CDATA[SiO2]]> 62.9 63.0 61.9 61.9 62.4 62.4 62.8 61.9 62.3 61.9 <![CDATA[Al2O3]]> 10.0 10.0 9.0 8.5 8.9 11.0 8.5 9.4 9.0 9.0 <![CDATA[B2O3]]> 17.0 17.0 21.1 22.0 21.1 17.0 21.1 21.1 21.1 21.1 MgO 3.4 6.0 0.6 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 SrO 6.2 0.2 7.0 70 7.0 8.0 7.0 7.0 7.0 7.0 BaO 0.2 3.6 0.2 0.2 0.2 1.2 0.2 0.2 0.2 0.6 ZnO 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Na2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[K2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Fe2O3]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 MgO + CaO + SrO + BaO 10.0 10.0 8.0 7.6 7.6 9.6 7.6 7.6 7.6 8.0 <![CDATA[R2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Al2O3 / B2O3]]> 0.59 0.59 0.43 0.39 0.42 0.65 0.40 0.45 0.43 0.43 <![CDATA[Al2O3-(MgO+CaO+SrO+BaO)]]> 0.00 0.00 1.00 0.90 1.30 1.40 0.90 1.80 1.40 1.00 SrO / (MgO+CaO+SrO+BaO) 0.62 0.02 0.88 0.92 0.92 0.83 0.92 0.92 0.92 0.88

[0186] [Table 5]

[0187] Table 5

[0188] <![CDATA[SiO2]]> 62.4 62.0 63.0 66.1 62.0 61.2 60.0 68.0 <![CDATA[Al2O3]]> 8.5 8.0 11.0 11.3 8.0 8.0 5.0 6.6 <![CDATA[B2O3]]> 21.1 19.0 17.0 7.8 23.0 23.0 28.0 19.5 MgO 0.2 4.0 3.0 5.1 4.0 4.0 2.0 0.5 CaO 0.2 2.0 5.6 4.5 2.0 2.0 3.0 4.9 SrO 7.0 1.0 0.2 5.2 0.8 0.8 2.0 0.5 BaO 0.6 4.0 0.2 0.0 0.2 0.2 0.0 0.0 ZnO 0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Na2O]]> 0 0.0 0.0 0.0 0.0 0.8 0.0 0.0 <![CDATA[K2O]]> 0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Fe2O3]]> 0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 MgO + CaO + SrO + BaO 8.0 11.0 9.0 14.8 7.0 7.0 7.0 5.9 <![CDATA[R2O]]> 0.0 0.0 0.0 0.0 0.0 0.8 0.0 0.0 <![CDATA[Al2O3 / B2O3]]> 0.40 0.42 0.65 1.45 0.35 0.35 0.18 0.34 <![CDATA[Al2O3-(MgO+CaO+SrO+BaO)]]> 0.50 -3.00 2.00 -3.58 1.00 1.00 -2.00 0.3 SrO / (MgO+CaO+SrO+BaO) 0.88 0.09 0.02 0.35 0.11 0.11 0.29 0.7

[0189] [Table 6]

[0190] Table 6

[0191]

[0192] [Table 7]

[0193] Table 7

[0194]

[0195] [Table 8]

[0196] Table 8

[0197]

[0198] [Table 9]

[0199] Table 9

[0200]

[0201] [Table 10]

[0202] Table 10

[0203]

[0204] [Table 11]

[0205] Table 11

[0206] <![CDATA[SiO2]]> 61.3 61.9 61.9 61.9 <![CDATA[Al2O3]]> 8.5 8.5 8.5 8.5 <![CDATA[B2O3]]> 21.1 21.1 21.1 21.1 MgO 0.2 0.2 0.2 0.2 CaO 0.2 0.2 0.2 0.2 SrO 7.0 7.0 7.0 7.0 BaO 1.1 1.1 1.1 1.1 ZnO 0.0 0.0 0.0 0.0 <![CDATA[Na2O]]> 0.0 0.0 0.0 0.0 <![CDATA[K2O]]> 0.0 0.0 0.0 0.0 <![CDATA[Fe2O3]]> 0.0 0.0 0.0 0.0 Cl 0.61 0.00 0.00 0.01 total 100.0 100.0 100.0 100.0 MgO + CaO + SrO + BaO 8.5 8.5 8.5 8.5 <![CDATA[R2O]]> 0.0 0.0 0.0 0.0 <![CDATA[Al2O3 / B2O3]]> 0.40 0.40 0.40 0.40 <![CDATA[Al2O3-(MgO+CaO+SrO+BaO)]]> 0.00 0.00 0.00 0.00 SrO / (MgO+CaO+SrO+BaO) 0.82 0.82 0.82 0.82 β-OH value 0.16 0.45 0.57 0.695 Relative permittivity @ 10 GHz 4.8 4.8 4.8 4.8 Dielectric loss tangent @ 10GHz 0.0028 0.0026 0.0025 0.0024

[0207] [Table 12]

[0208] Table 12

[0209] <![CDATA[SiO2]]> 61.9 61.8 61.7 61.0 61.8 61.8 61.6 61.4 60.0 <![CDATA[Al2O3]]> 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 <![CDATA[B2O3]]> 21.1 21.1 21.1 21.1 21.1 21.1 21.1 21.1 21.1 MgO 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 CaO 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 SrO 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 BaO 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 ZnO 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Li2O]]> 0.00 0.00 0.00 0.00 0.06 0.12 0.23 0.46 1.83 <![CDATA[Na2O]]> 0.02 0.09 0.22 0.89 0.02 0.02 0.02 0.02 0.02 <![CDATA[K2O]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 <![CDATA[Fe2O3]]> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 MgO + CaO + SrO + BaO 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 <![CDATA[R2O]]> 0.02 0.09 0.22 0.89 0.08 0.14 0.25 0.48 1.85 <![CDATA[Al2O3 / B2O3]]> 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 <![CDATA[Al2O3-(MgO+CaO+SrO+BaO)]]> 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 SrO / (MgO+CaO+SrO+BaO) 0.82 0.82 0.82 0.82 0.82 0.82 0.82 0.82 0.82 Relative permittivity @ 10 GHz 4.8 4.8 4.9 4.9 4.9 4.8 4.8 4.9 5.0 Dielectric loss tangent @ 10GHz 0.0025 0.0027 0.0029 0.0044 0.0026 0.0025 0.0026 0.0028 0.0041 Resistivity at 1500℃ [Ω·cm] 399 376 310 144 307 245 192 125 35

[0210] Although some of the glasses used in Examples 1 to 43 were not measured, the results all met multiple ranges of the following: an average coefficient of thermal expansion of 30 × 10⁻⁶ at 50–350°C. -7 / ℃~40×10 -7 / ℃, density is 2.58g / cm³ 3 The following parameters are specified: glass transition temperature below 700°C, Young's modulus above 58 GPa, T2 between 1500 and 1700°C, T4 below 1290°C, dielectric loss tangent below 0.006 at 35 GHz, and resistivity below 400 Ω·cm at 1500°C. Furthermore, based on haze measurements, no phase separation is confirmed.

[0211] When the Al₂O₃-(MgO+CaO+SrO+BaO) ratio is greater than -3 and less than 2, there is a tendency for the surface devitrification temperature to be below 1300℃, and the acid resistance becomes better. When the Al₂O₃-(MgO+CaO+SrO+BaO) ratio is 2 or higher, there is a tendency for the surface devitrification temperature to exceed 1300℃. When the Al₂O₃ / B₂O₃ ratio is 0.49 or higher, there is a tendency for the glass to have a high Young's modulus. When the SrO / (MgO+CaO+SrO+BaO) ratio is 0.64 or higher, there is a tendency for the glass to have a low surface devitrification temperature. Glasses with B₂O₃ content less than 15% and an Al₂O₃ / B₂O₃ ratio greater than 1.4 have a dielectric loss tangent higher than 0.006 at 35 GHz, and cannot reduce dielectric loss in the high-frequency region. In addition, the glass transition temperature exceeds 700℃. On the other hand, glasses with an Al₂O₃ / B₂O₃ ratio of less than 0.35 have poor acid resistance. Furthermore, phase separation was confirmed based on the haze measurement results. Glasses with B2O3 content exceeding 24% and an Al2O3 / B2O3 ratio exceeding 1.4 exhibit poor acid resistance. Additionally, phase separation was confirmed based on the haze measurement results. Moreover, the Young's modulus is less than 58 GPa.

[0212] Furthermore, the glasses in Examples 49 to 52, as embodiments, were obtained by changing the Cl content and β-OH value based on the glass composition of Example 30. It can be seen that a higher β-OH value may result in a relatively lower dielectric loss tangent, while a higher Cl content may result in a higher dielectric loss tangent.

[0213] The glasses in Examples 53 to 61, as examples, were obtained by changing the Li2O and Na2O content based on the glass composition of Example 30. When the Li2O and Na2O content increased, the resistivity at 1500°C decreased. Furthermore, Li2O can reduce the resistivity at 1500°C while maintaining a low dielectric loss tangent.

[0214] This invention has been described in detail and with reference to specific embodiments. However, various changes and modifications can be made without departing from the spirit and scope of the invention, which will be clear to those skilled in the art. This application is based on and incorporates by reference to Japanese patent applications filed on April 12, 2019 (Japanese Patent Application No. 2019-076423), June 28, 2019 (Japanese Patent Application No. 2019-120828), and November 27, 2019 (Japanese Patent Application No. 2019-214690).

[0215] Industrial availability

[0216] The alkali-free glass of this embodiment exhibits excellent acid resistance and can reduce dielectric loss of high-frequency signals. Glass plates containing such alkali-free glass are useful for all high-frequency electronic devices that handle high-frequency signals exceeding 10 GHz, especially exceeding 30 GHz, and further exceeding 35 GHz, such as glass substrates for communication equipment, frequency filter components like SAW devices and FBARs, bandpass filters like waveguides, SIW (Substrate Integrated Waveguide) components, radar components, antenna components (especially liquid crystal antennas best suited for satellite communications), window glass, and vehicle window glass.

Claims

1. An alkali-free glass, comprising, on an oxide basis, 61-70% SiO2, 5-11% Al2O3, 15-21.9% B2O3, 0.2-10% MgO, 0.1-7% CaO, 0.1-2% SrO, 0-3% BaO, and 0-0.1% ZnO, wherein formula (A) is [Al2O3] / [B2O3], and the value of formula (A) is 0.54-0.

65. Formula (B) is [MgO] + [CaO] + [SrO] + [BaO], and the value of formula (B) is 8% to 11.5%. Formula (C) is [Al2O3]-([MgO]+[CaO]+[SrO]+[BaO]), and the value of formula (C) is -3% to 0%.

2. The alkali-free glass according to claim 1, wherein, Formula (C) is [Al2O3]-([MgO]+[CaO]+[SrO]+[BaO]), and the value of formula (C) is -3% to -0.5%.

3. The alkali-free glass according to claim 1, wherein, Formula (C) is [Al2O3]-([MgO]+[CaO]+[SrO]+[BaO]), and the value of formula (C) is -3% to -1%.

4. The alkali-free glass according to claim 1, wherein, It contains less than 1 mol% Fe, calculated as Fe2O3.

5. The alkali-free glass according to claim 1, wherein, The β-OH value of the glass is 0.05 mm. －1 ~1.0mm －1 .

6. The alkali-free glass according to claim 1, wherein, The total content of [Li₂O] + [Na₂O] + [K₂O] is 0–0.2 mol%.

7. The alkali-free glass according to claim 1, wherein, It contains at least one of SnO2, Cl and SO3, with a total percentage of less than 1 mol%.

8. The alkali-free glass according to claim 1, wherein, Contains at least one of the following: Sc2O3, TiO2, ZnO, Ga2O3, GeO2, Y2O3, ZrO2, Nb2O5, In2O3, TeO2, HfO2, Ta2O5, WO3, Bi2O3, La2O3, Gd2O3, Yb2O3, and Lu2O3, with a total content of less than 1 mol%.

9. The alkali-free glass according to claim 1, wherein, It contains less than 1 mol% of F.

10. The alkali-free glass according to claim 1, wherein, The dielectric loss tangent at 35GHz is below 0.

006.

11. The alkali-free glass according to claim 1, wherein, The resistance at 1500℃ is less than 400Ω·cm.

12. The alkali-free glass according to claim 1, wherein, The resistance at 1500℃ is less than 300Ω·cm.

13. The alkali-free glass according to claim 1, wherein, The Young's modulus is above 58 GPa.

14. The alkali-free glass according to claim 1, wherein, The density is 2.58 g / cm³. 3 The average coefficient of thermal expansion for temperatures ranging from 50 to 350°C is 30 × 10⁻⁶. －7 / ℃~40×10 －7 / ℃.

15. The alkali-free glass according to claim 1, wherein, The glass viscosity becomes 10 2 The temperature T2 of dPa·s is 1500~1700℃, and the glass viscosity is 10. 4 The temperature T4, dPa·s, is below 1290℃.

16. The alkali-free glass according to claim 1, wherein, The glass transition temperature is below 700℃, or the strain point is below 700℃.

17. The alkali-free glass according to claim 1, wherein, The surface devitrification temperature is below 1300℃.

18. The alkali-free glass according to claim 1, wherein, The leaching amount of glass component per unit surface area after immersion in an aqueous solution containing 6% by weight HNO3 and 5% by weight H2SO4 at 45°C for 170 seconds was 0.025 mg / cm³. 2 the following.

19. A glass plate comprising the alkali-free glass according to any one of claims 1 to 18 and having a main surface and an end face, wherein the arithmetic mean roughness Ra of at least one main surface is less than 1.5 nm.

20. The glass plate according to claim 19, wherein, At least one side must be 900mm or more, and the thickness must be less than 0.7mm.

21. The glass plate according to claim 19 or 20, which is manufactured using a float glass process or a melting process.

22. A glass substrate for high-frequency devices, comprising the alkali-free glass according to any one of claims 1 to 18.

23. A panel-type antenna comprising the alkali-free glass according to any one of claims 1 to 18.

24. A window glass comprising the alkali-free glass according to any one of claims 1 to 18.

25. A vehicle window glass comprising any one of claims 1 to 18.

26. A cover glass for a touch panel, comprising the alkali-free glass according to any one of claims 1 to 18.

Images