Alkali-free glass and glass plates

Abstract

To provide an alkali-free glass which combines a low dielectric dissipation factor in the high-frequency range with acid resistance.SOLUTION: An alkali-free glass includes, as represented by mole percentage based on oxides, SiO2 of 57-70%, Al2O3 of 5-15%, B2O3 of 15-24%, MgO of 0.2-10%, CaO of 0.1-7%, SrO of 0.1-2.5%, BaO of 0-10%, and ZnO of 0-0.1%. The value of formula (A) represented by [Al2O3] / [B2O3] is more than 0.35 and 1.4 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to alkali-free glass. It also relates to glass plates containing such alkali-free glass, glass substrates for high-frequency devices, panel antennas, window glass, vehicle window glass, and cover glass for touch panels. [Background technology]

[0002] Examples of electronic devices include communication equipment such as mobile phones, smartphones, personal digital assistants (PDAs), and Wi-Fi devices, as well as surface acoustic wave (SAW) devices, radar components, and antenna components. In such electronic devices, the signal frequency is being increased to achieve higher communication capacities and faster communication speeds. Circuit boards used in high-frequency electronic equipment generally use insulating substrates such as resin substrates, ceramic substrates, and glass substrates. Insulating substrates used in high-frequency devices are required to reduce transmission losses due to dielectric loss and conductor loss in order to ensure the quality and strength of high-frequency signals.

[0003] Of these insulating substrates, resin substrates have low rigidity due to their properties. Therefore, resin substrates are difficult to apply when rigidity (strength) is required for semiconductor packaging products. Ceramic substrates have the drawback that it is difficult to improve surface smoothness, which tends to increase conductor loss due to conductors formed on the substrate surface. On the other hand, glass substrates have high rigidity, making it easy to miniaturize and thin packages, and they also have excellent surface smoothness and can be easily enlarged as substrates themselves.

[0004] However, while conventional alkali-free glass substrates are effective in reducing dielectric loss and the resulting transmission loss up to about 20 GHz, beyond that, for example, in the region exceeding 30 GHz, there are limitations in reducing dielectric loss. Therefore, in circuit boards using conventional alkali-free glass substrates, it becomes difficult to maintain characteristics such as the quality and intensity of high-frequency signals exceeding 30 GHz. On the other hand, while quartz glass substrates can maintain low dielectric loss even in regions exceeding 30 GHz, their thermal expansion coefficient is too small, resulting in an excessive difference in thermal expansion coefficient from other members when constructing electronic devices. This is a factor that reduces the practicality of electronic devices.

[0005] Patent Document 1 discloses a glass substrate for high-frequency devices with a dielectric tangent of 0.0007 or less at 35 GHz. In the glass substrate for high-frequency devices described in Patent Document 1, it is stated that the dielectric tangent can be made 0.0007 or less by satisfying predetermined conditions for the amounts and ratios of Al2O3 and B2O3. Therefore, it is considered that to reduce dielectric loss in the high-frequency region exceeding 30 GHz, the B2O3 content should be increased.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, increasing the B2O3 content reduces the chemical resistance of the glass. In the manufacturing process of circuit boards for liquid crystal antennas, high-frequency devices, etc., chemical cleaning is performed as a pretreatment before forming a wiring layer on the glass substrate. If the glass has low chemical resistance, for example, during acid cleaning, the substrate surface may dissolve, impairing the smoothness of the substrate surface, which may reduce the adhesion of the film formed on the substrate surface. In addition, there is a risk that leached substances may adhere to the substrate surface. This may increase the conductor loss caused by the conductors formed on the substrate surface.

[0008] The present invention aims to provide alkali-free glass that achieves both low dielectric loss tangent and acid resistance in the high-frequency range. [Means for solving the problem]

[0009] As a result of diligent research, the inventors have found that the above objective can be achieved by adopting the following configuration. [1] Alkali-free glass containing, on an oxide basis, SiO2 57-70%, Al2O3 5-15%, B2O3 15-24%, MgO 0.2-10%, CaO 0.1-7%, SrO 0.1-2.5%, BaO 0-10%, and ZnO 0-0.1%, with formula (A) being [Al2O3] / [B2O3], and the value of formula (A) being greater than 0.35 and less than or equal to 1.4. [2] Alkali-free glass containing, on an oxide basis, SiO2 57-70%, Al2O3 5-15%, B2O3 15-24%, MgO 0.1-10%, CaO 0.1-10%, SrO 0.1-10%, BaO 0.1-10%, and ZnO 0-0.1%, wherein formula (A) is [Al2O3] / [B2O3], and the value of formula (A) is greater than 0.35 and less than or equal to 1.4. [3] 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% or more and 16% or less. [4] The alkali-free glass according to any one of [1] to [3] above, wherein the value of formula (B) is 8% or more and 16% or less. [5] The alkali-free glass according to any one of [1] to [4] above, wherein formula (C) is [Al2O3]-([MgO]+[CaO]+[SrO]+[BaO]), and the value of formula (C) is greater than -3% and less than 2%. [6] The alkali-free glass according to any one of [1] to [5] above, wherein the value of formula (A) is 0.49 or greater. [7] The 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 greater. [8] The alkali-free glass according to any one of [1] to [7] above, which contains 1 mol% or less of Fe on an Fe2O3 basis. [9] The β-OH value of the glass is 0.05 mm -1 Above, 1.0 mm -1 The alkali-free glass described in any one of the above [1] to [8], which is as follows:

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

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

[10] above, which contains a total of 1 mol% or less of at least one selected from the group consisting of SnO2, Cl, and SO3.

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

[11] above, containing in total 1 mol% or less at least one selected from the group consisting of Sc2O3, TiO2, ZnO2, Ga2O3, GeO2, Y2O3, ZrO2, Nb2O5, In2O3, TeO2, HfO2, Ta2O5, WO3, Bi2O3, La2O3, Gd2O3, Yb2O3, and Lu2O3.

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

[12] above, containing 1 mol% or less of F.

[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.

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

[14] above, wherein the resistance value at 1500℃ is 400 Ω·cm or less.

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

[15] above, wherein the resistance value at 1500℃ is 300 Ω·cm or less.

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

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

[18] Density is 2.58 g / cm³ 3 The average coefficient of thermal expansion between 50 and 350°C is 30 × 10⁻⁶. -7 / ℃~40×10 -7 Alkali-free glass according to any one of [1] to

[17] above, wherein the temperature is / ℃.

[19] Glass viscosity is 10 2 The temperature T2 at which the viscosity is dPa·s is 1500-1700°C, and the glass viscosity is 10 4 Alkali-free glass according to any one of [1] to

[18] above, wherein the temperature T4 at which dPa·s is obtained is 1290°C or less.

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

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

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

[20] above, wherein the surface devitrification temperature is 1300°C or less.

[22] When immersed for 170 seconds in an aqueous solution at 45°C containing 6% by weight of HNO3 and 5% by weight of H2SO4, the amount of glass components eluted per unit surface area was 0.025 mg / cm². 2 The alkali-free glass described in any one of the above [1] to

[21] , which is as follows:

[23] A glass plate comprising alkali-free glass as described in any one of [1] to

[22] above, having a main surface and an end surface, wherein at least one main surface has an arithmetic mean roughness Ra of 1.5 nm or less.

[24] The glass plate described in

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

[25] The glass plate according to

[22] or

[23] , manufactured by the float method or the fusion method.

[26] A glass substrate for high-frequency devices containing alkali-free glass as described in any one of [1] to

[22] above.

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

[22] above.

[28] Window glass containing alkali-free glass as described in any one of [1] to

[22] above.

[29] Vehicle window glass containing alkali-free glass as described in any one of [1] to

[22] above.

[30] A cover glass for a touch panel, comprising alkali-free glass as described in any one of [1] to

[22] above. [Effects of the Invention]

[0010] 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 and provide practical high-frequency devices such as electronic devices. The alkali-free glass of the present invention exhibits excellent acid resistance. Therefore, when glass substrates are acid-cleaned during the manufacturing process of circuit boards such as liquid crystal antennas and high-frequency devices, there is no risk of the substrate surface dissolving, deteriorating the surface smoothness, or of leached substances adhering to the substrate surface. This prevents a decrease in the adhesion of films formed on the substrate surface. Furthermore, it prevents an increase in conductor loss. The alkali-free glass of the present invention can reduce the transmission loss of radio waves in the high frequency band and is resistant to damage and breakage. Therefore, it is suitable for glass products that transmit and receive radio waves in the high frequency band. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of the configuration of a circuit board for high-frequency devices. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below. In the following description, numerical ranges indicated using "~" represent ranges that include the numerical values ​​before and after "~" as the minimum and maximum values, respectively. Unless otherwise specified, the content of each component in alkali-free glass and glass plates is given as mole percentage (mol%) based on oxides. In addition, the notation [metal oxide] in formulas (A) to (D), such as [MgO], represents the mole percentage of a metal oxide component, such as magnesium oxide. In this specification, "high frequency" means 10 GHz or higher, preferably greater than 30 GHz, and more preferably 35 GHz or higher.

[0013] The alkali-free glass according to this embodiment (hereinafter sometimes simply referred to as "glass") will be described below.

[0014] If the SiO2 content as a network-forming material is 57 mol% (hereinafter simply referred to as %) or more, the glass-forming ability and weather resistance can be improved, and devitrification can be suppressed. 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, the solubility of the glass can be improved. 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.

[0015] Al2O3 is a component that exhibits effects such as improving weather resistance, improving Young's modulus, suppressing phase separation of glass, and lowering the coefficient of thermal expansion. A content of 5% or more of Al2O3 is sufficient to obtain the desired effects. A content of 6% or more is preferable, 7% or more is more preferable, and 8% or more is even preferable. Furthermore, a content of 15% or less of Al2O3 results in good glass solubility. A content of 14% or less is preferable, 13% or less is more preferable, and 12% or less is even preferable.

[0016] If the B2O3 content is 24% or less, good chemical 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. In addition, the dielectric loss tangent in the high-frequency range can be reduced. The B2O3 content is preferably 16% or more, more preferably 17% or more, and even more preferably 17.5% or more.

[0017] MgO is a component that increases Young's modulus without increasing specific gravity. In other words, MgO is a component that increases the specific modulus of elasticity, thereby reducing the problem of deflection, improving fracture toughness, and increasing glass strength. MgO is also a component that improves solubility. If the MgO content is 0.1% or more, the effect of including 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 can be 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, especially preferably 5% or less, particularly preferably 4% or less, and most preferably 3% or less.

[0018] CaO is a component that, among alkaline earth metals, has the second highest specific modulus after MgO, and does not excessively lower the strain point, and like MgO, it also improves solubility. Furthermore, it is a component that does not easily raise the devitrification temperature compared to MgO. If the CaO content is 0.1% or more, the effect of including CaO is sufficiently obtained. The CaO content is preferably 0.2% or more, more preferably 0.5% or more, even more preferably 1% or more, and particularly preferably 2% or more. Also, if the CaO content is 10% or less, the average coefficient of thermal expansion does not become too high, and the rise in the devitrification temperature is suppressed, preventing devitrification during glass manufacturing. The CaO content is preferably 8% or less, more preferably 7% or less, even more preferably 6% or less, even more preferably 5% or less, especially preferably 4% or less, and particularly preferably 3% or less.

[0019] SrO is a component that improves solubility without raising the devitrification temperature of glass. A SrO content of 0.1% or more is sufficient to obtain the effect of including SrO. A SrO content of 0.2% or more is preferable, 0.5% or more is more preferable, 1% or more is even preferable, and 2% or more is particularly preferable. If the SrO content is 10% or less, the specific gravity will not increase too much, and the average thermal expansion coefficient will not become too high. A SrO content of 9% or less is preferable, 8% or less is more preferable, 7% or less is even preferable, 6% or less is even preferable, 5% or less is particularly preferable, 4% or less is even preferable, 3% or less is particularly preferable, and 2.5% or less is most preferable.

[0020] BaO is not an essential component, but it does not raise the devitrification temperature of the glass and improves its solubility. When BaO is included, a content of 0.1% or more is preferable because the effects of including BaO as described above are sufficiently obtained. A BaO content of 0.2% or more is more preferable, 1% or more is even more preferable, and 2% or more is particularly preferable. However, a high BaO content tends to increase the specific gravity, decrease the Young's modulus, increase the dielectric constant, and make the average thermal expansion coefficient too large. Therefore, a BaO content of 10% or less is preferable, 8% or less is more preferable, 5% or less is even more preferable, and 3% or less is even more preferable.

[0021] ZnO is not an essential component, but it is a component that improves chemical resistance. However, a high ZnO content can lead to phase separation and may also raise the devitrification temperature. Therefore, the ZnO content is 0.1% or less. Preferably, the ZnO content is 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%.

[0022] In this embodiment, when formula (A) is the content ratio represented by [Al2O3] / [B2O3], the value of formula (A) is greater than 0.35 and less than or equal to 1.4. If the value represented by formula (A) is within the above range, dielectric loss in the high-frequency region exceeding 30 GHz can be reduced, and the acid resistance of the glass is improved. In addition, phase separation is suppressed, resulting in glass with excellent uniformity. If the value represented by formula (A) is 0.35 or less, the acid resistance of the glass deteriorates. In addition, it becomes difficult to obtain glass with excellent uniformity due to phase separation. If the value represented by formula (A) is greater than 1.4, dielectric loss in the high-frequency region exceeding 30 GHz cannot be reduced. The value represented by formula (A) is preferably 1.2 or less, more preferably 1.0 or less, and even more preferably 0.8 or less. The value represented by formula (A) is preferably 0.40 or more, more preferably 0.45 or more, and even more preferably 0.49 or more. Furthermore, a value of 0.49 or higher is even more preferable, as it improves the Young's modulus, for example, to 64 GPa or higher. A value of 0.52 or higher is even more preferable, 0.56 or higher is particularly preferable, 0.59 or higher is especially preferable, and 0.61 or higher is most preferable.

[0023] In this embodiment, when formula (B) represents the total content of [MgO] + [CaO] + [SrO] + [BaO], the value represented by formula (B) is preferably 7% or more and 16% or less. If the value represented by formula (B) is within the above range, the resistance value in the melting temperature range, for example, the resistance value at 1500°C, becomes low, and the acid resistance of the glass is improved. The alkali-free glass of this embodiment, which has a low resistance value in the melting temperature range, can have its productivity and quality improved by applying electrolysis during the melting of the glass raw materials. Specifically, if the value represented by formula (B) is 7% or more, the resistance value in the melting temperature range can be lowered. If the value represented by formula (B) is 16% or less, the acid resistance of the glass can be further improved. In addition, dielectric loss in the high-frequency range exceeding 30 GHz can be suitably reduced. The value represented by formula (B) is more preferably 14% or less, even more 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, even more preferably 8.5% or more, and even more preferably 9% or more.

[0024] In this embodiment, when the alkali-free glass has a content represented by formula (C) [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, if the value represented by formula (C) is greater than -3%, the acid resistance of the glass can be made even better. If 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, even more preferably 1.0% or less, and particularly preferably 0.5% or less. The value represented by formula (C) is more preferably -2% or more, even more preferably -1% or more, and particularly preferably -0.5% or more.

[0025] For the alkali-free glass according to this embodiment, when the content ratio represented by the formula (D) is [SrO] / ([MgO]+[CaO]+[SrO]+[BaO]), the value of the formula (D) is preferably 0.64 or more. If the value represented by the 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 productivity of the glass is improved. The value of the formula (D) is more preferably 0.7 or more, further preferably 0.75 or more, and particularly preferably 0.8 or more. The upper limit is not particularly limited, but for example, 0.95 or less is preferable.

[0026] The alkali-free glass according to this embodiment may contain Fe in order to lower the resistance value in the melting temperature range, for example, the resistance value at 1500 °C. However, from the viewpoint of suppressing the decrease in the transmittance in the visible region, the Fe content is preferably 1 mol% or less, more preferably 0.5 mol% or less, and further preferably 0.1 mol% or less in terms of Fe2O3 conversion.

[0027] The alkali-free glass according to this embodiment has a β-OH value (mm -1 ) of 0.05 mm -1 or more and 1.0 mm -1 or less is preferable. The β-OH value is an index of the moisture content in the glass. The absorbance of the glass sample for light with a wavelength of 2.75 to 2.95 μm is measured, and the maximum value β max of the absorbance is divided by the thickness (mm) of the sample to obtain it. When the β-OH value is within the above range, the resistance value in the temperature range for melting the glass raw material, for example, around 1500 °C, becomes low, which is suitable for melting the glass by electric heating, and there are few bubble defects in the glass. Specifically, when the β-OH value is 0.05 mm -1 or more, the resistance value in the temperature range for melting the glass raw material becomes low. Also, the dielectric loss tangent in the high-frequency region can be suitably reduced. When the β-OH value is 1.0 mm -1 or less, the bubble defects in the glass can be suppressed. The β-OH value is more preferably 0.8 mm -1 or less, further preferably 0.6 mm -1 or less, and particularly preferably 0.5 mm -1 or less. The β-OH value is 0.1 mm -1The above is more preferable, 0.2 mm -1 The above is even more preferable, 0.3 mm -1 The above are particularly preferable.

[0028] The alkali-free glass according to this embodiment preferably contains substantially no alkali metal oxides such as Li2O, Na2O, and K2O. In this embodiment, substantially no alkali metal oxides means that they are not contained except for unavoidable impurities introduced from the raw materials, that is, they are intentionally omitted. However, alkali metal oxides may be included in a predetermined amount for the purpose of obtaining specific effects, such as lowering the strain point, lowering the Tg, lowering the annealing point, or lowering the resistance value in the temperature range in which the glass raw materials melt. Specifically, at least one selected from the group consisting of Li2O, Na2O, and K2O may be contained in a total content of 0.2% or less, expressed as [Li2O]+[Na2O]+[K2O]. More preferably 0.15% or less, even more preferably 0.1% or less, even more preferably 0.08% or less, especially preferably 0.05% or less, and most preferably 0.03% or less. At least one selected from the group consisting of Li2O, Na2O, and K2O may be contained in a total of 0.001% or more, expressed as mole percent on an oxide basis. More preferably 0.003% or more, even more preferably 0.005% or more, even more preferably 0.008% or more, especially preferably 0.01% or less, and most preferably 0.02% or more. In this specification, the total content expressed as [Li2O]+[Na2O]+[K2O] may also be represented as R2O, where R refers to an alkali metal.

[0029] To improve the clarity of the glass, the alkali-free glass according to this embodiment may contain at least one selected from the group consisting of SnO2, Cl, and SO3 in a total content of preferably 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 present). From the viewpoint of reducing bubble defects in the glass and reducing the dielectric loss tangent in the high-frequency range, the Cl content of the alkali-free glass according to this embodiment is preferably 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 present).

[0030] To improve the acid resistance of the glass, the alkali-free glass according to this embodiment may contain at least one trace component selected from the group consisting of Sc2O3, TiO2, ZnO2, Ga2O3, GeO2, Y2O3, ZrO2, Nb2O5, In2O3, TeO2, HfO2, Ta2O5, WO3, Bi2O3, La2O3, Gd2O3, Yb2O3, and Lu2O3. However, if the content of trace components is too high, the uniformity of the glass will decrease and phase separation will be more likely to occur, so it is preferable that the total content of trace components be 1 mol% or less. The glass may contain only one of the above-mentioned trace components, or it may contain two or more.

[0031] For purposes such as improving the solubility of the glass, lowering the strain point of the glass, lowering the glass transition temperature, and lowering the annealing point, the alkali-free glass according to this embodiment may contain up to 1 mol% of F. If the F content exceeds 1 mol%, there is a risk of an increase in bubble defects in the glass.

[0032] To improve the solubility, clarity, and moldability of the glass, and to obtain absorption at specific wavelengths, and to improve density, hardness, bending rigidity, and durability, the alkali-free glass according to this embodiment may contain one or more of the following: Se2O3, TeO2, Ga2O3, In2O3, GeO2, CdO, BeO, and Bi2O3. The total content of these is preferably 2% or less, more preferably 1% or less, even more preferably 0.5% or less, even more preferably 0.3% or less, especially preferably 0.1% or less, particularly preferably 0.05% or less, and most preferably 0.01% or less.

[0033] In order to improve the solubility, clarity, and moldability of the glass, and to improve the hardness of the glass, such as Young's modulus, the alkali-free glass according to this embodiment may contain rare earth oxides and transition metal oxides.

[0034] The alkali-free glass according to this embodiment may contain one or more of the following rare earth oxides: Sc2O3, Y2O3, La2O3, Ce2O3, Pr2O3, Nd2O3, Pm2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Dy2O3, Ho2O3, Re2O3, Tm2O3, Yb2O3, and Lu2O3. The total content of these is preferably 2% or less, more preferably 1% or less, even more preferably 0.5% or less, even more preferably 0.3% or less, especially preferably 0.1% or less, particularly preferably 0.05% or less, and most preferably 0.01% or less.

[0035] The alkali-free glass according to this embodiment may contain one or more transition metal oxides from among V2O5, Ta2O3, Nb2O5, WO3, MoO3, and HfO2. The total content of these is preferably 2% or less, more preferably 1% or less, even more preferably 0.5% or less, even more preferably 0.3% or less, especially preferably 0.1% or less, particularly preferably 0.05% or less, and most preferably 0.01% or less.

[0036] To improve the solubility of the glass, the alkali-free glass according to this embodiment may contain ThO2, which is an actinide oxide. The ThO2 content is preferably 2% or less, more preferably 1% or less, even more preferably 0.5% or less, even more preferably 0.3% or less, especially preferably 0.1% or less, still more preferably 0.05% or less, particularly preferably 0.01% or less, and most preferably 0.005% or less.

[0037] In this embodiment, the alkali-free glass preferably has a dielectric loss tangent (tanδ) of 0.006 or less at 35 GHz. If the dielectric loss tangent at 35 GHz is 0.006 or less, dielectric loss in the high-frequency region exceeding 30 GHz can be reduced. The dielectric loss tangent at 35 GHz is more preferably 0.0054 or less, even more preferably 0.005 or less, even more preferably 0.0045 or less, especially preferably 0.004 or less, and particularly preferably 0.003 or less. 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.

[0038] In this embodiment, the alkali-free glass preferably has a relative permittivity of 10 or less at 35 GHz. A relative permittivity of 10 or less at 35 GHz can reduce dielectric loss in the high-frequency range. A relative permittivity of 7 or less at 35 GHz is more preferably, 6 or less is even more preferably, and 5 or less is particularly preferably. 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.

[0039] Furthermore, when alkali-free glass is used as a glass substrate for high-frequency devices, a high Young's modulus is required. If the Young's modulus is low, problems such as warping, bending, or cracking of the glass substrate may occur after the deposition of a metal (e.g., Cu) film during the device manufacturing process. Alkali-free glass with a low dielectric loss tangent tends to have a low Young's modulus. The alkali-free glass according to this embodiment preferably has a Young's modulus of 58 GPa or higher. If the Young's modulus is within the above range, it is possible to suppress problems such as warping, bending, or cracking of the glass substrate after the formation of a metal film, such as a Cu film, which is carried out in the manufacturing process of high-frequency devices. A Young's modulus of 60 GPa or higher is more preferable, 62 GPa or higher is even more preferable, 63 GPa or higher is even more preferable, 64 GPa or higher is particularly preferable, 65 GPa or higher is even more preferable, 66 GPa or higher is particularly preferable, 67 GPa or higher is especially preferable, and 68 GPa or higher is most preferable.

[0040] The alkali-free glass according to this embodiment has a specific modulus of 23 GPa·cm², which suppresses the amount of glass deflection. 3 Preferably 24 GPa·cm² or more 3 More preferably 25 GPa·cm² or more. 3 A value of 1 / g or higher is even more preferable. The upper limit is not particularly limited, but for example, 32 GPa·cm 3 Preferably less than / g

[0041] The alkali-free glass according to this embodiment has a density of 2.58 g / cm³. 3 The following is preferable: This reduces self-weight deflection, making it easier to handle large substrates. It also allows for weight reduction of devices using glass. The density is 2.57 g / cm³. 3 The following is more preferable: 2.56 g / cm³ 3 The following is even more preferable. A large substrate is, for example, a substrate with at least one side measuring 900 mm or more.

[0042] The alkali-free glass according to this embodiment has an average thermal expansion coefficient of 30 × 10 at 50 to 350°C. -7 A temperature of 2°C or higher is preferable. This helps to prevent cracking caused by an excessive difference in expansion rates between the glass substrate and the metal film formed on the glass substrate. The average coefficient of thermal expansion between 50 and 350°C is 33 × 10⁻⁶. -7 / ℃ or higher is more preferable, 35 × 10 -7 More preferably above / ℃, 36 × 10-7 More preferably above / ℃, and particularly preferably 37×10 -7 / ℃ or higher, most preferably 38 × 10 -7 It is above / ℃. On the other hand, the average thermal expansion coefficient at 50-350°C is 43 × 10⁻¹⁰, from the perspective of suppressing glass breakage in the manufacturing process of products such as high-frequency devices. -7 A temperature of / ℃ or lower is preferable. The average coefficient of thermal expansion at 50-350°C is 42 × 10⁻⁶. -7 A temperature of / ℃ or lower is more preferable, 41.5 × 10 -7 More preferably below / ℃, 41 × 10 -7 More preferably below / ℃, 40.5 × 10 -7 / ℃ or lower is particularly preferred, 40.3 × 10 -7 / ℃ or lower is particularly preferred, 40 × 10 -7 A temperature of / ℃ or lower is most preferable.

[0043] The alkali-free glass according to this embodiment has a glass viscosity of 10 2 A temperature T2 of 1700°C or lower is preferred for the temperature at which dPa·s is obtained. A T2 of 1700°C or lower allows for excellent glass solubility and reduces the burden on manufacturing equipment. For example, it can extend the lifespan of equipment such as glass melting furnaces, thereby improving productivity. Furthermore, it can reduce furnace-derived defects, such as pitting and Zr defects. A T2 of 1680°C or lower is more preferable, and 1670°C or lower is even more preferable. A T2 of 1500°C or higher is preferred.

[0044] The alkali-free glass according to this embodiment has a glass viscosity of 10 4 A temperature T4 of 1290°C or lower is preferred for the temperature at which dPa·s is obtained. This results in excellent formability of the glass. Furthermore, for example, lowering the temperature during glass molding reduces volatile matter in the atmosphere surrounding the glass, thereby reducing defects in the glass. Since glass can be molded at a lower temperature, the burden on manufacturing equipment can be reduced. For example, the lifespan of equipment such as the float bath used for glass molding can be extended, improving productivity. A T4 of 1280°C or lower is more preferable. There is no particular lower limit, but for example, 1050°C or higher is preferred. T2 and T4 were determined by measuring the viscosity using a rotational viscometer according to the method specified in ASTM C 965-96, and 10 2 d·Pa·s or 10 4 The temperature at which the temperature becomes d·Pa·s can be determined. In the embodiments described later, NBS710 and NIST717a were used as reference samples for instrument calibration.

[0045] The glass transition temperature of the alkali-free glass according to this embodiment is preferably 700°C or lower. This avoids the need to raise the temperature of the annealing device, thereby suppressing a decrease in the lifespan of the annealing device. A glass transition temperature of 680°C or lower is more preferable, and 670°C or lower is even more preferable. A glass transition temperature of 600°C or higher is preferable. This suppresses deformation and shrinkage (thermal shrinkage) of the glass plate when the glass plate is processed at high temperature in the high-frequency device manufacturing process. A glass transition temperature of 620°C or higher is more preferable, and 630°C or higher is particularly preferable. Furthermore, the alkali-free glass according to this embodiment exhibits superior formability when its strain point is low. The strain point is preferably 700°C or lower, more preferably 670°C or lower, and even more preferably 660°C or lower. The lower limit of the strain point is not particularly limited, but for example, 550°C or higher is preferred.

[0046] In this embodiment, the alkali-free glass preferably has a surface devitrification temperature of 1300°C or lower. This results in excellent formability of the glass. It is possible to suppress the formation of crystals inside the glass during molding, which would reduce the transmittance. Furthermore, it is possible to reduce the burden on manufacturing equipment. For example, the lifespan of equipment such as the float bath used to mold the glass can be extended, and productivity can be improved. The surface devitrification temperature is further preferably in the following order: 1295°C or lower, 1290°C or lower, 1285°C or lower, 1280°C or lower, 1275°C or lower, 1270°C or lower, 1265°C or lower, 1260°C or lower, 1255°C or lower, 1250°C or lower, 1245°C or lower, 1240°C or lower, 1235°C or lower, 1230°C or lower, 1225°C or lower, 1220°C or lower, 1215°C or lower, 1210°C or lower, 1205°C or lower, and 1200°C or lower. The lower limit is not particularly limited, but for example, 1000°C or higher is preferred. In this embodiment, the surface devitrification temperature can be determined as follows. Specifically, crushed glass particles are placed in a platinum dish and heat-treated for 17 hours in an electric furnace controlled to a constant temperature. After the heat treatment, the highest temperature at which crystals precipitate on the glass surface and the lowest temperature at which crystals do not precipitate are observed using an optical microscope, and the average value of these is taken as the surface devitrification temperature.

[0047] In this embodiment, when the alkali-free glass is immersed for 170 seconds in an aqueous solution at 45°C containing 6% by weight of HNO3 and 5% by weight of H2SO4, the amount of glass components eluted per unit surface area is 0.025 mg / cm². 2 The following is preferable: The amount of glass component eluted is 0.025 mg / cm³. 2 The following conditions indicate good acid resistance: The amount of glass component leached out is 0.020 mg / cm³. 2 The following are more preferable, and the fewer the better.

[0048] If the B2O3 content of alkali-free glass is increased, when the glass raw materials in the melting tank are heated and melted with a burner or the like, a large amount of B2O3 is released during the melting process, resulting in low productivity. On the other hand, electromelting, which involves directly applying current to the molten glass from electrodes in a melting tank and melting the glass raw material with the resulting Joule heat, can suppress the amount of B2O3 volatilized because it forms a cold top layer on the substrate of the molten glass (Japanese Patent Publication No. 5-163024). However, alkali-free glass with a low dielectric loss tangent tends to have a higher resistance in the melting temperature range. When the resistance in the melting temperature range is high, the difference between it and the resistance of the furnace material that makes up the melting tank body becomes small, and current may flow through the furnace material that makes up the walls of the melting tank. When current flows through the furnace material, problems arise such as the melting of the glass raw material being inhibited, the furnace material being eroded, power consumption increasing, and manufacturing costs increasing (International Publication No. 2019 / 004434). In addition, if current is passed through the furnace material, the furnace material may break and become mixed into the glass, potentially resulting in the inclusion of foreign matter in the glass product. In contrast to the above, the alkali-free glass according to this embodiment preferably has a resistance value of 400 Ω·cm or less at 1500°C. If the resistance value at 1500°C is within the above range, melting by electric heating is possible during glass manufacturing. The resistance value at 1500°C is more preferably 300 Ω·cm or less, even more preferably 250 Ω·cm or less, and even more preferably 200 Ω·cm or less. The lower limit is not particularly limited, but it is 10 Ω·cm or more.

[0049] In this embodiment, the haze value of the alkali-free glass substrate with a thickness of 1 mmt is preferably 1.0% or less. This ensures high uniformity of the glass, and effectively prevents localized irregularities from occurring on the substrate surface when the glass substrate is acid-cleaned, for example. This reduces the transmission loss of high-frequency signals. In this embodiment, the haze value of the alkali-free glass substrate with a thickness of 1 mmt is more preferably 0.8% or less, more preferably 0.5% or less, most preferably 0.4% or less, and the smaller the value, the better.

[0050] Due to the characteristics described above, the alkali-free glass according to this embodiment is suitable for applications such as glass substrates for high-frequency devices, panel antennas, window glass, vehicle window glass, and cover glass for touch panels. Figure 1 is a cross-sectional view showing an example of the configuration of a circuit board for high-frequency devices. The circuit board 1 shown in Figure 1 comprises an insulating glass substrate 2, a first wiring layer 3 formed on the first main surface 2a of the glass substrate 2, and a second wiring layer 4 formed on the second main surface 2b of the glass substrate 2. The first and second wiring layers 3 and 4 form a microstrip line as an example of a transmission line. The first wiring layer 3 constitutes a signal line, and the second wiring layer 4 constitutes a ground line. However, the structure of the first and second wiring layers 3 and 4 is not limited to this. Furthermore, the wiring layers may be formed on only one of the main surfaces of the glass substrate 2.

[0051] The first and second wiring layers 3 and 4 are layers formed of a conductor, and their thickness is typically around 0.1 to 50 μm. The conductors forming the first and second wiring layers 3 and 4 are not particularly limited, and can be metals such as steel, gold, silver, aluminum, titanium, chromium, molybdenum, tungsten, platinum, nickel, alloys or metal compounds containing at least one of these metals. The structure of the first and second wiring layers 3 and 4 is not limited to a single-layer structure, but may have a multi-layer structure, such as a laminated structure of a titanium layer and a copper layer. The method for forming the first and second wiring layers 3 and 4 is not particularly limited, and can be any known method such as printing using a conductor paste, dipping, plating, vapor deposition, or sputtering.

[0052] If a glass substrate containing alkali-free glass according to this embodiment is used as the glass substrate 2, the dielectric loss tangent (tanδ) at 35 GHz will be 0.006 or less. The relative permittivity of the glass substrate 2 at 35 GHz is preferably 10 or less. A dielectric loss tangent of 0.006 or less for the glass substrate 2 at 35 GHz can reduce dielectric loss in the high-frequency region exceeding 30 GHz. A relative permittivity of 10 or less for the glass substrate 2 at 35 GHz can also reduce dielectric loss in the high-frequency region. The dielectric loss tangent of the glass substrate 2 at 35 GHz is more preferably 0.0054 or less, even more preferably 0.005 or less, even more preferably 0.0045 or less, especially 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, even more preferably 6 or less, and particularly preferably 5 or less.

[0053] Furthermore, the glass substrate 2 has main surfaces 2a and 2b and an end face. At least one of the main surfaces 2a and 2b on which the first and second wiring layers 3 and 4 are formed on the glass substrate 2 preferably has an arithmetic mean roughness Ra of 1.5 nm or less, and more preferably both main surfaces have an arithmetic mean roughness Ra of 1.5 nm or less. This reduces the skin resistance of the first and second wiring layers 3 and 4 even when the skin effect occurs in the first and second wiring layers 3 and 4 in high-frequency regions exceeding 30 GHz, thereby reducing conductor loss. The arithmetic mean roughness Ra of the main surfaces 2a and 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 on which the wiring layer is formed. If the wiring layer is formed on one of the main surfaces, it is sufficient that the arithmetic mean roughness Ra of that one main surface is 1.5 nm or less. In this specification, the surface roughness Ra refers to the value in accordance with JIS B0601 (2001).

[0054] The surface roughness of the main surfaces 2a and 2b of the glass substrate 2 can be achieved as needed by polishing the surface of the glass substrate 2. For polishing the surface of the glass substrate 2, for example, polishing using an abrasive mainly composed of cerium oxide or colloidal silica and a polishing pad; polishing using a polishing slurry containing an abrasive and an acidic or alkaline dispersion medium and a polishing pad; or polishing using an acidic or alkaline etching solution. These polishing treatments are applied according to the surface roughness of the raw material of the glass substrate 2, and for example, pre-polishing and finish polishing may be applied in combination. In addition, it is preferable to chamfer the edges of the glass substrate 2 to prevent cracking, chipping, or breakage of the glass substrate 2 caused by the edges during process flow. The chamfering can be any of the following: C-chamfering, R-chamfering, thread chamfering, etc.

[0055] The use of such a glass substrate 2 reduces the transmission loss of the circuit board 1 at 35 GHz, specifically to 1 dB / cm or less. Therefore, the characteristics such as quality and intensity of high-frequency signals, especially those exceeding 30 GHz and even 35 GHz, are maintained, providing a glass substrate 2 and circuit board 1 suitable for high-frequency devices handling such signals. In other words, the characteristics and quality of high-frequency devices handling such signals can be improved. A transmission loss of 0.5 dB / cm or less at 35 GHz for the circuit board 1 is more preferable.

[0056] The shape of the glass plate containing alkali-free glass according to this embodiment is not particularly limited, but a thickness of 0.7 mm or less is preferred. If the thickness of the glass plate is 0.7 mm or less, when used as a glass substrate for high-frequency devices, it is possible to make high-frequency devices thinner and smaller, and to improve production efficiency. In addition, the ultraviolet transmittance is improved, and manufacturability can be enhanced by using ultraviolet curing materials in the device manufacturing process. The thickness of the glass plate is more preferably 0.6 mm or less, even more preferably 0.5 mm or less, even more preferably 0.4 mm or less, still even more preferably 0.3 mm or less, especially preferably 0.2 mm or less, and particularly preferably 0.1 mm or less. The lower limit is about 0.01 mm.

[0057] When the glass plate is used as a large substrate, it is preferable that at least one side is 900 mm or longer, and more preferably 1000 mm or longer. There is no particular upper limit, but the size of one side is usually 4000 mm or less. Furthermore, the glass plate is preferably rectangular in shape.

[0058] Next, a method for manufacturing glass plates containing alkali-free glass will be described. When manufacturing glass plates, the process involves a melting step in which glass raw materials are heated to obtain molten glass, a clarification step in which bubbles are removed from the molten glass, a molding step in which the molten glass is formed into a plate to obtain a glass ribbon, and a slow cooling step in which the glass ribbon is slowly cooled to room temperature. Alternatively, a method may be used in which the molten glass is formed into a block, slowly cooled, and then cut and polished to produce a glass plate.

[0059] The melting process involves preparing the raw materials to achieve the target glass composition, continuously feeding the raw materials into a melting furnace, and heating them to a temperature of preferably 1450°C to 1750°C to obtain molten glass. In this embodiment, the alkali-free glass has a low resistance value in the temperature range where the glass raw materials melt, for example, around 1500°C. Therefore, it is preferable to use an electric melting furnace and melt the glass by electric heating. However, electric heating and heating with a burner may be used in combination.

[0060] The raw materials can also include halides such as oxides, carbonates, nitrates, hydroxides, and chlorides. In processes where molten glass comes into contact with platinum during dissolution or clarification, minute platinum particles may dissolve into the molten glass and become foreign matter in the resulting glass plate. However, using nitrate raw materials is effective in preventing the formation of platinum foreign matter.

[0061] As nitrates, strontium nitrate, barium nitrate, magnesium nitrate, calcium nitrate, etc. can be used. The use of strontium nitrate is more preferable. The particle size of the raw materials can be used as appropriate, from large particles of several hundred μm that do not leave any undissolved residue, to small particles of several μm that do not scatter during raw material transport and do not aggregate as secondary particles. Granulated materials can also be used. The water content of the raw materials can be adjusted as appropriate to prevent scattering of the raw materials. β-OH value, redox degree of Fe (redox [Fe 2+ / ( Fe 2+ +Fe 3+ The dissolution conditions for )) can also be adjusted as appropriate.

[0062] The next clarification step is to remove bubbles from the molten glass obtained in the dissolution step described above. For the clarification step, a defoaming method by reduced pressure may be applied, or defoaming may be performed by raising the temperature above the dissolution temperature of the raw materials. SO3 or SnO2 can also be used as a clarifying agent. As an SO3 source, sulfates of at least one element selected from Al, Na, K, Mg, Ca, Sr, and Ba are preferred, and sulfates of alkaline earth metals are more preferred, with CaSO4·2H2O, SrSO4, and BaSO4 being particularly preferred because they have a significant effect in increasing the size of bubbles.

[0063] In the defoaming method by reduced pressure, the use of halogens such as Cl or F is preferred as a clarifying agent. As a Cl source, chlorides of at least one element selected from Al, Mg, Ca, Sr, and Ba are preferred, alkaline earth metal chlorides are more preferred, and among these, SrCl2·6H2O and BaCl2·2H2O are particularly preferred because they significantly increase foam size and have low deliquescence. As a F source, fluorides of at least one element selected from Al, Na, K, Mg, Ca, Sr, and Ba are preferred, alkaline earth metal fluorides are more preferred, and among these, CaF2 is even more preferred because it significantly increases the solubility of the glass raw material.

[0064] Tin compounds, such as SnO2, generate O2 gas in molten glass. In molten glass, at temperatures of 1450°C or higher, SnO2 is reduced to SnO, generating O2 gas and promoting the growth of large bubbles. During the manufacture of glass plates, the glass raw materials are heated to approximately 1450-1750°C to melt, which allows the bubbles in the molten glass to grow more effectively. When using SnO2 as a clarifying agent, it is preferable to prepare the raw materials so that they contain 0.01% or more of the tin compound, calculated as SnO2, relative to 100% of the total amount of the base composition. A SnO2 content of 0.01% or more is preferable because it provides a clarifying effect during the melting of the glass raw materials, more preferably 0.05% or more, and even more preferably 0.10% or more. A SnO2 content of 0.3% or less is preferable because it suppresses the occurrence of glass discoloration and devitrification. The tin compound content in the glass is more preferably 0.25% or less, even more preferably 0.2% or less, and particularly preferably 0.15% or less, based on SnO2 equivalent relative to 100% of the total amount of the glass matrix composition.

[0065] The next molding step is to form the molten glass, from which bubbles have been removed in the clarification step described above, into a plate shape to obtain a glass ribbon. As for the molding step, known methods for forming glass into a plate shape can be applied, such as the float method, in which molten glass is poured onto a molten metal such as tin to form a plate shape and obtain a glass ribbon; the overflow down-draw method (fusion method), in which molten glass is poured downwards from a trough-shaped member; and the slit down-draw method, in which molten glass is poured down through a slit. Among these, the float method or the fusion method are preferred from the viewpoint of no polishing or light polishing.

[0066] Next, the annealing process involves cooling the glass ribbon obtained in the molding process down to room temperature under controlled cooling conditions. The annealing process involves cooling the glass ribbon to form a glass ribbon, and then further annealing it down to room temperature under predetermined conditions. After cutting the annealed glass ribbon, a glass plate is obtained.

[0067] If the cooling rate R in the slow cooling process is too high, distortion is likely to remain in the glass after cooling. Also, the equivalent cooling rate, which is a parameter that reflects the virtual temperature, becomes too high, and as a result, glass shrinkage cannot be reduced. For this reason, it is preferable to set R so that the equivalent cooling rate is 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 time required for the process becomes too long, resulting in low productivity. For this reason, 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.

[0068] Here, the definition and evaluation method of the equivalent cooling rate are as follows: A glass sample is prepared by processing a glass of the target composition into a rectangular parallelepiped measuring 10 mm × 10 mm × 0.3 to 2.0 mm. The glass sample is heated in an infrared electric furnace and held at the strain point + 1700°C for 5 minutes, after which the glass sample is cooled to room temperature (25°C). At this time, multiple glass samples are prepared by changing the cooling rate in the range from 10°C / min to 1000°C / min.

[0069] Using a precision refractive index measuring device (e.g., Shimadzu Devices KPR2000), the d-line (wavelength 587.6 nm) refractive index n of multiple glass samples is measured. d Measure the n. The V-block method or the minimum angle method may be used for measurement. d By plotting against the logarithm of the cooling rate, n relative to the cooling rate is obtained. d Obtain a calibration curve.

[0070] Next, n of glass of the same composition that was actually manufactured through processes such as melting, molding, and cooling. d The obtained n is measured by the measurement method described above. d The corresponding cooling rate (referred to as the equivalent cooling rate in this embodiment) is determined from the calibration curve described above.

[0071] The present invention is not limited to the embodiments described above. Modifications and improvements are permitted as long as they can achieve the objectives of the present invention. For example, when manufacturing a glass plate according to this embodiment, the glass may be formed into a plate by a press molding method that directly shapes molten glass into a plate.

[0072] Furthermore, when manufacturing the glass plate according to this embodiment, in addition to the manufacturing method using a melting tank made of refractory material, a crucible made of platinum or an alloy mainly composed of platinum (hereinafter referred to as a platinum crucible) may be used as the melting tank or clarification tank. When a platinum crucible is used, the melting process involves preparing the raw materials to achieve the composition of the glass plate to be obtained, heating the platinum crucible containing the raw materials in an electric furnace, preferably to about 1450°C to 1700°C, and inserting a platinum stirrer to stir for 1 to 3 hours to obtain molten glass.

[0073] In the molding process of manufacturing glass plates using a platinum crucible, molten glass is poured onto, for example, a carbon plate or into a mold to form a plate or block. The annealing process typically involves holding the glass at a temperature of approximately Tg + 50°C, then cooling it at a rate of approximately 1-10°C / min to near the strain point, and then cooling it to room temperature at a rate that does not leave any strain. After cutting and polishing to the desired shape, a glass plate is obtained. Alternatively, the cut glass plate may be heated to, for example, approximately Tg + 50°C, and then annealed to room temperature at a predetermined cooling rate. In this way, the equivalent cooling temperature of the glass can be adjusted.

[0074] The circuit board 1 using alkali-free glass as the glass substrate 2 according to this embodiment is suitable for high-frequency devices that handle high-frequency signals, particularly high-frequency signals exceeding 30 GHz, and even high-frequency signals exceeding 35 GHz, and can reduce the transmission loss of such high-frequency signals and improve characteristics such as the quality and strength of the high-frequency signals. The circuit board 1 using alkali-free glass as the glass substrate 2 according to this embodiment is suitable for high-frequency devices (electronic devices) such as semiconductor devices used in communication equipment such as mobile phones, smartphones, personal digital assistants, and Wi-Fi devices, as well as surface acoustic wave (SAW) devices, radar components such as radar transceivers, and antenna components such as liquid crystal antennas and panel antennas. In other words, the present invention relates not only to a glass substrate for high-frequency devices containing alkali-free glass according to this embodiment, but also to a panel-type antenna containing alkali-free glass according to this embodiment.

[0075] Furthermore, the present invention can suitably apply the alkali-free glass according to this embodiment to other products for the purpose of reducing transmission loss of high-frequency signals. In other words, the present invention also relates to window glass, vehicle window glass, and touch panel cover glass containing such alkali-free glass. Glass plates containing alkali-free glass can stably transmit and receive radio waves in the high frequency band and are resistant to damage and breakage, making them suitable for window glass, vehicle windows, and touch panel cover glass. For vehicle windows, for example, windows for autonomous vehicles are more preferable. [Examples]

[0076] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Examples 1 to 43 and Examples 49 to 61 are examples, and Examples 44 to 48 are comparative examples.

[0077] [Examples 1-61] Glass plates were prepared with the compositions shown in Tables 1-5, 11, and 12 (expressed in molar percentages based on oxides), a thickness of 1.0 mm, a shape of 50 × 50 mm, and an arithmetic mean surface roughness Ra of 1.0 nm. The glass plates were manufactured by a melting method using a platinum crucible. Raw materials such as silica sand were mixed to obtain glass with the compositions shown in Tables 1-5, 11, and 12, and 1 kg batches were prepared. The raw materials were placed in a platinum crucible and heated in an electric furnace at a temperature of 1650°C for 3 hours to melt the glass. During melting, a platinum stirrer was inserted into the platinum crucible and stirred for 1 hour to homogenize the glass. The molten glass was poured onto a carbon plate and formed into a plate shape, and then the plate-shaped glass was placed in an electric furnace at a temperature of approximately Tg + 50°C and held for 1 hour. The electric furnace was cooled to Tg-100°C at a cooling rate of 1°C / min, and then the glass was allowed to cool to room temperature. After that, the glass was cut and polished to form a sheet, and a glass plate was obtained.

[0078] Tables 6-12 show the average thermal expansion coefficient, density, glass transition temperature, Young's modulus, specific modulus, T2, T4, β-OH value, relative permittivity at 50-350°C, dielectric loss tangent at 10GHz or 35GHz, surface devitrification temperature, acid resistance, haze value, and resistivity at 1500°C for glass plates of Examples 1-48. The haze value is an indicator of the phase separation of the glass. Blank spaces in the tables indicate that the data was not measured.

[0079] The measurement methods for each physical property are shown below. (density) The density of a 20g glass mass, free of bubbles, was measured using the Archimedes method. (Average thermal expansion coefficient) Measurements were taken using a differential thermal expander in accordance with the method specified in JIS R3102 (1995). The measurement temperature range was 50 to 350°C, and the unit was ppm / °C or ×10⁻⁶. -7 It was expressed as / ℃. (Glass transition temperature) The measurement was performed using the thermal expansion method in accordance with the method specified in JIS R3103-3 (2001). (Young's modulus) Measurements were taken using the ultrasonic pulse method on glass with a thickness of 0.5 to 10 mm, in accordance with the method specified in JIS Z2280 (1993). The unit is expressed as GPa. (Specific modulus of elasticity) The specific modulus (GPa·cm²) obtained by dividing the Young's modulus measured by the method described above by the density also measured by the same method is obtained by dividing the Young's modulus by the density. 3 The value per gram ( / g) was calculated. (T2) The viscosity was measured using a rotational viscometer according to the method specified in ASTM C 965-96, and 10 2 The temperature T2 (°C) at which the temperature was d·Pa·s was measured. (T4) The viscosity was measured using a rotational viscometer according to the method specified in ASTM C 965-96, and 10 4 The temperature T4 (°C) at which the temperature was d·Pa·s was measured. (Relative permittivity, dielectric loss tangent) Measurements were performed using a cavity resonator and a vector network analyzer, in accordance with the method specified in JIS R1641 (2007). The measurement frequency was 10 GHz or 35 GHz, which are the resonant frequencies of the air in the cavity resonator. (Surface devitrification temperature) The glass was crushed and classified using a test sieve to obtain particles in the range of 2-4 mm. The resulting glass cullet was ultrasonically cleaned in isopropyl alcohol for 5 minutes, washed with deionized water, dried, placed in a platinum dish, and heat-treated in an electric furnace controlled to a constant temperature for 17 hours. The heat treatment temperature was set in 10°C increments. After heat treatment, the glass was removed from the platinum dish, and the highest temperature at which crystals precipitated on the glass surface and the lowest temperature at which crystals did not precipitate were observed using an optical microscope. The highest temperature at which crystals precipitate on the glass surface and the lowest temperature at which crystals do not precipitate were each measured once. (In cases where it is difficult to determine crystal precipitation, measurements may be taken twice.) The average value was calculated using the highest temperature at which crystals precipitated on the glass surface and the lowest temperature at which crystals did not precipitate, and this value was defined as the surface devitrification temperature. (acid resistance) The glass sample was immersed in an acidic aqueous solution (6% by mass HNO3 + 5% by mass H2SO4, 45°C) for 170 seconds, and the amount of glass components eluted per unit surface area (mg / cm³) was measured. 2 The following was evaluated: The amount of glass components eluted was 0.02 mg / cm³. 2 The following conditions indicate good acid resistance. (β-OH value) The absorbance of the glass sample was measured for light with wavelengths of 2.75 to 2.95 μm, and the maximum absorbance value β was determined. max The β-OH value was determined by dividing the value by the thickness (mm) of the sample. (Resistivity at 1500℃) The resistivity of molten glass was measured in the temperature range of 1350 to 1700°C. The molten glass was prepared by mixing the components to the predetermined composition and melting them at 1650°C using a platinum crucible. During the melting of the glass, a platinum stirrer was used to stir and homogenize the glass. Next, the resistivity of the molten glass was measured while it was held at 1500°C using the method described in the following document: "Method for measuring the conductivity of ionic melts, Yoshio Ota, Hikaru Miyanaga, Kenji Morinaga, Tsutomu Yanagase, Journal of the Japan Institute of Metals, Vol. 45, No. 10 (1981), pp. 1036-1043." (Haze value) The haze value of glass was measured using a haze meter (manufacturer: Suga Test Instruments Co., Ltd., model: HZ-V3 Hazemeter). The haze value was measured on a glass plate with a thickness of 1 mm and both sides polished to a mirror finish. Glass with a haze value of 35% or less was considered a good product.

[0080] [Table 1]

[0081] Table 2

[0082] Table 3

[0083] Table 4

[0084] Table 5

[0085] Table 6

[0086] Table 7

[0087] Table 8

[0088] Table 9

[0089] Table 10

[0090] Table 11

[0091] [Table 12]

[0092] The glass samples in Examples 1-43, which are examples of the implementation, all have an average thermal expansion coefficient of 30 × 10⁻¹⁰ at 50-350°C, although some measurements were not taken. -7 / ℃~40×10 -7 / ℃, density 2.58 g / cm³ 3 The results showed that the device satisfied most of the following criteria: glass transition temperature of 700°C or less, Young's modulus of 58 GPa or higher, T2 of 1500-1700°C, T4 of 1290°C or less, dielectric loss tangent at 35 GHz of 0.006 or less, and resistance at 1500°C of 400 Ω·cm or less. Furthermore, the absence of phase separation was confirmed from the haze value measurement results. When the Al2O3-(MgO+CaO+SrO+BaO) ratio was greater than -3 and less than 2, the surface devitrification temperature tended to be 1300°C or lower, indicating good acid resistance. When the Al2O3-(MgO+CaO+SrO+BaO) ratio was 2 or higher, the surface devitrification temperature tended to be above 1300°C. When the Al2O3 / B2O3 value was 0.49 or higher, the Young's modulus of the glass tended to be high. When the SrO / (MgO+CaO+SrO+BaO) ratio was 0.64 or higher, the surface devitrification temperature of the glass tended to be low. Glass with less than 15% B2O3 and an Al2O3 / B2O3 value greater than 1.4 had a dielectric loss tangent at 35 GHz higher than 0.006, indicating that dielectric loss in the high-frequency range could not be reduced. In addition, the glass transition temperature was above 700°C. On the other hand, glass with an Al2O3 / B2O3 value of 0.35 or less exhibited poor acid resistance. Furthermore, phase separation was confirmed from the haze value measurement results. Glass with more than 24% B2O3 and an Al2O3 / B2O3 value greater than 1.4 also exhibited poor acid resistance. Phase separation was also confirmed from the haze value measurement results. Additionally, the Young's modulus was less than 58 GPa. Furthermore, the glasses in Examples 49-52, which are examples, are based on the glass composition of Example 30, but with changes in Cl content and β-OH value. From these, it can be seen that increasing the β-OH value may relatively lower the dielectric loss tangent, and that increasing the Cl content may increase the dielectric loss tangent. The glasses in Examples 53-61, which are examples of the design, are based on the glass composition of Example 30, but with modified Li2O and Na2O content. Increasing the Li2O and Na2O content lowers the resistivity at 1500°C. Furthermore, Li2O can lower the resistivity at 1500°C while maintaining a low dielectric loss tangent.

[0093] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2019-076423 filed on April 12, 2019, Japanese Patent Application No. 2019-120828 filed on June 28, 2019, and Japanese Patent Application No. 2019-214690 filed on November 27, 2019, the contents of which are incorporated herein by reference. [Industrial applicability]

[0094] The alkali-free glass according to this embodiment has excellent acid resistance and can reduce dielectric loss of high-frequency signals. Glass plates containing such alkali-free glass are useful in a wide range of high-frequency electronic devices that handle high-frequency signals exceeding 10 GHz, especially those exceeding 30 GHz, and even those exceeding 35 GHz, such as glass substrates for communication equipment, frequency filter components such as SAW devices and FBARs, bandpass filters such as waveguides and SIW (Substrate Integrated waveguide) components, radar components, antenna components (especially liquid crystal antennas which are considered ideal for satellite communications), window glass, and vehicle window glass. [Explanation of Symbols]

[0095] 1: Circuit board 2: Glass substrate 2a, 2b: Main surface 3,4: Wiring layer

Claims

1. A glass plate comprising alkali-free glass and having a main surface and an end surface, The alkali-free glass mentioned above is In mole percentage based on oxides, Yes ２ 61~70%, Al ２ O ３ 5~11% B ２ O ３ 21.9% or less, MgO 0.2-10%, CaO 0.1-7%, SrO 0.1-3.3%, BaO 0-3%, Contains 0-0.1% ZnO, Formula (A) is [Al ２ O ３ / [B ２ O ３ , and the value of the formula (A) is 0.54 or more and 0.65 or less. A glass plate in which equation (B) is [MgO] + [CaO] + [SrO] + [BaO], and the value of equation (B) is 8 or greater and 10.5 or less.

2. Equation (C) is [Al ２ O ３ ] - ([MgO] + [CaO] + [SrO] + [BaO]) The glass plate according to claim 1, wherein the value of formula (C) is greater than -3 and less than 2%.

3. Equation (C) is [Al ２ O ３ ] - ([MgO] + [CaO] + [SrO] + [BaO]) The glass plate according to claim 1, wherein the value of formula (C) is greater than -3 and less than 0%.

4. Equation (C) is [Al ２ O ３ ] - ([MgO] + [CaO] + [SrO] + [BaO]) The glass plate according to claim 1, wherein the value of formula (C) is greater than -3 to -0.5%.

5. Equation (C) is [Al ２ O ３ ] - ([MgO] + [CaO] + [SrO] + [BaO]) The glass plate according to claim 1, wherein the value of formula (C) is greater than -3 to -1%.

6. Fe ２ O ３ A glass plate according to claim 1 or 2, which contains Fe in an equivalent amount of 1 mol% or less.

7. The β-OH value of the glass is 0.05 mm －１ Above, 1.0 mm －１ The glass plate according to claim 1 or 2, which is as follows:

8. [Li ２ O] + [Na] ２ O] + [K ２ The glass plate according to claim 1 or 2, wherein the total content represented by [O] is 0 to 0.2 mol%.

9. SnO ２ , Cl and SO ３ A glass plate according to claim 1 or 2, which contains a total of 1 mol% or less of at least one selected from the group consisting of the following.

10. Sc ２ O ３ , TiO ２ ZnO, Ga ２ O ３ , GeO ２ , Y ２ O ３ , ZrO ２ Nb ２ O ５ In ２ O ３ TeO ２ , HfO ２ Ta ２ O ５ WO ３ , Bi ２ O ３ La ２ O ３ , Gd ２ O ３ Yb ２ O ３ , and Lu ２ O ３ A glass plate according to claim 1 or 2, which contains a total of 1 mol% or less of at least one selected from the group consisting of the following.

11. A glass plate according to claim 1 or 2, containing F in an amount of 1 mol% or less.

12. The glass plate according to claim 1 or 2, wherein the dielectric loss tangent at 35 GHz is 0.006 or less.

13. The glass plate according to claim 1 or 2, wherein the resistance value at 1500°C is 400 Ω·cm or less.

14. The glass plate according to claim 1 or 2, wherein the resistance value at 1500°C is 300 Ω·cm or less.

15. A glass plate according to claim 1 or 2, wherein the Young's modulus is 58 GPa or higher.

16. Density is 2.58 g / cm³ ３ The average coefficient of thermal expansion between 50 and 350°C is 30 × 10⁻⁶. －７ / ℃~40×10 －７ A glass plate according to claim 1 or 2, wherein the temperature is / ℃.

17. Glass viscosity is 10 ２ The temperature T2 at which dPa·s is obtained is 1500-1700°C, and the glass viscosity is 10 ４ The glass plate according to claim 1 or 2, wherein the temperature T4 at which dPa·s is obtained is 1290°C or less.

18. A glass plate according to claim 1 or 2, wherein the glass transition temperature is 700°C or less, or the strain point is 700°C or less.

19. A glass plate according to claim 1 or 2, wherein the surface devitrification temperature is 1300°C or less.

20. HNO ３ 6% by weight and H ２ SO ４ When immersed for 170 seconds in an aqueous solution containing 5% by weight of [the substance] at 45°C, the amount of glass component eluted per unit surface area was 0.025 mg / cm². ２ The glass plate according to claim 1 or 2, which is as follows:

21. The glass plate according to claim 1 or 2, wherein at least one of the main surfaces has an arithmetic mean roughness Ra of 1.5 nm or less.

22. A glass plate according to claim 1 or 2, wherein at least one side is 900 mm or longer and the thickness is 0.7 mm or less.

23. In terms of molar percentage based on oxide, SiO 2 61-70%, Al 2 O 3 5-11% B 2 O 3 21.9% or less, MgO 0.2-10%, CaO 0.1-7%, SrO 0.1-3.3%, BaO 0-3%, Contains 0-0.1% ZnO, Formula (A) is [Al₂O₃] / [B₂O₃], and the value of formula (A) is 0.54 or greater and 0.65 or less. A glass substrate for high-frequency devices containing alkali-free glass, wherein formula (B) is [MgO] + [CaO] + [SrO] + [BaO], and the value of formula (B) is 8 or greater and 10.5 or less.

24. In terms of molar percentage based on oxide, SiO 2 61-70%, Al 2 O 3 5-11% B 2 O 3 21.9% or less, MgO 0.2-10%, CaO 0.1-7%, SrO 0.1-3.3%, BaO 0-3%, Contains 0-0.1% ZnO, Formula (A) is [Al₂O₃] / [B₂O₃], and the value of formula (A) is 0.54 or greater and 0.65 or less. A panel antenna containing alkali-free glass, wherein equation (B) is [MgO] + [CaO] + [SrO] + [BaO], and the value of equation (B) is 8 or greater and 10.5 or less.

25. In terms of molar percentage based on oxide, SiO 2 61-70%, Al 2 O 3 5-11% B 2 O 3 21.9% or less, MgO 0.2-10%, CaO 0.1-7%, SrO 0.1-3.3%, BaO 0-3%, Contains 0-0.1% ZnO, Formula (A) is [Al₂O₃] / [B₂O₃], and the value of formula (A) is 0.54 or greater and 0.65 or less. Window glass containing alkali-free glass, wherein formula (B) is [MgO] + [CaO] + [SrO] + [BaO], and the value of formula (B) is 8 or greater and 10.5 or less.

26. In terms of molar percentage based on oxide, SiO 2 61-70%, Al 2 O 3 5-11% B 2 O 3 21.9% or less, MgO 0.2-10%, CaO 0.1-7%, SrO 0.1-3.3%, BaO 0-3%, Contains 0-0.1% ZnO, Formula (A) is [Al₂O₃] / [B₂O₃], and the value of formula (A) is 0.54 or greater and 0.65 or less. Vehicle window glass containing alkali-free glass, wherein formula (B) is [MgO] + [CaO] + [SrO] + [BaO], and the value of formula (B) is 8 or more and 10.5 or less.

27. ​​In terms of molar percentage based on oxide, SiO 2 61-70%, Al 2 O 3 5-11% B 2 O 3 21.9% or less, MgO 0.2-10%, CaO 0.1-7%, SrO 0.1-3.3%, BaO 0-3%, Contains 0-0.1% ZnO, Formula (A) is [Al₂O₃] / [B₂O₃], and the value of formula (A) is 0.54 or greater and 0.65 or less. A touch panel cover glass containing alkali-free glass, wherein formula (B) is [MgO] + [CaO] + [SrO] + [BaO], and the value of formula (B) is 8 or greater and 10.5 or less.

Images