Glass substrates, liquid crystal antennas and high frequency devices

Abstract

The present invention provides a glass substrate that can reduce dielectric loss of high-frequency signals and has excellent thermal shock resistance. The glass substrate satisfies the relationship: {Young's modulus (GPa) × average thermal expansion coefficient (ppm / °C) at 50 to 350°C} ≦ 300 (GPa ppm / °C), has a relative dielectric constant of 10 or less at 20°C and 35 GHz, and has a dielectric loss tangent of 0.006 or less at 20°C and 35 GHz.

Description

[Technical Field]

[0001] The present invention relates to a glass substrate, and a liquid crystal antenna and a high-frequency device having the glass substrate. [Background technology]

[0002] In electronic devices such as communication devices like mobile phones, smartphones, personal digital assistants, and Wi-Fi devices, as well as surface acoustic wave (SAW) devices, radar components, and antenna components, signal frequencies are becoming higher in order to increase communication capacity and speed. Circuit boards used in such high-frequency communication devices and electronic devices generally use insulating substrates such as resin substrates, ceramic substrates, and glass substrates. Insulating substrates used in high-frequency communication devices and electronic devices are required to reduce transmission loss due to dielectric loss, conductor loss, and the like in order to ensure characteristics such as the quality and strength of high-frequency signals.

[0003] For example, Patent Document 1 discloses that by setting the dielectric loss tangent of the insulating substrate and the wiring width and surface roughness of the wiring layer within specific ranges, it is possible to maintain transmission loss at conventional levels and suppress crosstalk noise. Also, Patent Document 2 discloses that by using lead-free glass with a specific composition, it is possible to obtain an electronic circuit board with a low relative permittivity or dielectric loss.

[0004] Among these insulating substrates, resin substrates have low rigidity due to their characteristics. Therefore, resin substrates are difficult to use when rigidity (strength) is required for semiconductor package products. In addition, it is difficult to improve the surface smoothness of ceramic substrates, which has the drawback of increasing conductor loss due to the conductor formed on the substrate surface.

[0005] On the other hand, glass substrates have high rigidity, which makes it easy to make packages smaller and thinner, and they also have excellent surface smoothness, and the substrate itself can easily be made larger.

[0006] Furthermore, with the spread of IoT, various devices are now equipped with communication functions, and there is a growing need to install communication devices even in vehicles that have not previously performed wireless communication, such as automobiles. For this reason, it is conceivable that a communication device such as an LCD antenna could be attached to the roof of a vehicle to communicate with a satellite (see Patent Documents 3 and 4). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2013-077769 [Patent Document 2] Japanese Patent Application Publication No. 2004-244271 [Patent Document 3] Japan Special Publication No. 2017-506467 [Patent Document 4] Japan Special Publication No. 2017-506471 Summary of the Invention [Problem to be solved by the invention]

[0008] However, conventional glass substrates have a large dielectric loss tangent, especially in the GHz band, making it difficult to maintain characteristics such as the quality and strength of high-frequency signals.In addition, when used as a perforated substrate, the glass substrate is prone to cracking due to thermal shock caused by temperature differences within the substrate during laser processing for drilling the holes.

[0009] Furthermore, while antenna applications are intended for outdoor use, communication devices have traditionally been used indoors or in protected spaces. However, when mounted on automobiles, ships, and other vehicles, these devices are used in harsh environments with large temperature changes, and accompanying LCD antennas and other devices exposed to the outside air are likely to be exposed to sudden temperature changes, such as being heated by sunlight and then suddenly cooled by rain. In contrast, conventional glass substrates used in electronic devices are prone to cracking due to the thermal shock caused by sudden temperature changes.

[0010] In view of the above circumstances, an object of the present invention is to provide a glass substrate that can reduce the dielectric loss of high-frequency signals and has excellent thermal shock resistance, as well as a liquid crystal antenna and a high-frequency device that use the same. [Means for solving the problem]

[0011] As a result of extensive research conducted by the present inventors to achieve the above object, it was found that excellent resistance to thermal shock caused by sudden temperature changes can be achieved by setting the value expressed by the product of Young's modulus and the average thermal expansion coefficient at 50 to 350° C. to a certain value or less. This makes the substrate suitable for use in substrates used in environments with large temperature changes, such as liquid crystal antennas, and substrates for high-frequency circuits that require hole drilling using a laser or the like.

[0012] That is, the glass substrate according to the present invention satisfies the relationship of {Young's modulus (GPa) × average thermal expansion coefficient at 50 to 350°C (ppm / °C)} ≦ 300 (GPa ppm / °C), has a relative dielectric constant of 10 or less at 20°C and 35 GHz, and has a dielectric loss tangent of 0.006 or less at 20°C and 35 GHz.

[0013] In one aspect of the glass substrate according to the present invention, the glass substrate is used for a liquid crystal antenna or a high-frequency circuit.

[0014] Moreover, one aspect of a liquid crystal antenna or a high-frequency device according to the present invention includes the glass substrate. [Effects of the Invention]

[0015] The glass substrate according to the present invention can reduce the dielectric loss of high-frequency signals. Furthermore, because it has excellent thermal shock resistance, it is suitable for use in environments with large temperature changes, or for use in substrates that are subjected to laser or other hole drilling processes. Therefore, it is possible to provide high-performance and practical liquid crystal antennas and high-frequency devices. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the configuration of a high-frequency circuit. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be practiced with any modifications within the scope of the gist of the present invention. Furthermore, the symbol "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the lower limit and upper limit.

[0018] The content of each component in the glass substrate is expressed as mole percentage on an oxide basis unless otherwise specified. Furthermore, "high frequency" means a frequency of 10 GHz or higher, preferably above 30 GHz, and more preferably 35 GHz or higher.

[0019] <Glass substrate> The glass substrate (hereinafter sometimes simply referred to as the substrate) according to the present invention is characterized by satisfying the relationship of {Young's modulus (GPa) × average thermal expansion coefficient at 50 to 350°C (ppm / °C)} ≦ 300 (GPa ppm / °C), having a relative dielectric constant of 10 or less at 20°C and 35 GHz, and a dielectric loss tangent of 0.006 or less at 20°C and 35 GHz.

[0020] By setting the value expressed by the formula {Young's modulus (GPa) × average thermal expansion coefficient at 50 to 350°C (ppm / °C)} (hereinafter sometimes referred to as Formula 2) to 300 GPa·ppm / °C or less, even if distortion occurs in the substrate due to a difference in thermal expansion, the stress applied to the substrate is reduced, thereby improving thermal shock resistance.

[0021] The value represented by the above formula 2 is preferably 280 GPa·ppm / °C or less, more preferably 250 GPa·ppm / °C or less, even more preferably 220 GPa·ppm / °C or less, and even more preferably 200 GPa·ppm / °C or less. On the other hand, there is no particular lower limit, but from the viewpoints of ensuring the rigidity of the substrate and obtaining a substrate that is easy to manufacture, a value of 100 GPa·ppm / °C or more is preferred.

[0022] By reducing the Young's modulus, the value represented by the above formula 2 is reduced, and the stress applied to the substrate is reduced, thereby improving the thermal shock resistance. Therefore, the Young's modulus of the glass substrate is preferably 70 GPa or less, more preferably 67 GPa or less, even more preferably 64 GPa or less, and even more preferably 60 GPa or less.

[0023] On the other hand, when the glass substrate is used in a high-frequency circuit, the Young's modulus is preferably 40 GPa or more, more preferably 50 GPa or more, and even more preferably 55 GPa or more, in order to reduce the amount of bending of the substrate during the manufacturing process (wafer process) of the high-frequency device and thereby prevent the occurrence of manufacturing defects.

[0024] The Young's modulus can be adjusted by the composition and thermal history of the glass substrate. The Young's modulus can be measured by the ultrasonic pulse method according to the method specified in JIS Z 2280 (1993).

[0025] Distortion due to thermal shock occurs due to thermal expansion or contraction caused by a temperature difference between two points in the glass. A smaller thermal expansion coefficient reduces distortion even with the same temperature difference, thereby improving thermal shock resistance. Therefore, the average thermal expansion coefficient at 50 to 350°C is preferably small, preferably 5 ppm / °C or less, more preferably 4 ppm / °C or less, even more preferably 3.5 ppm / °C or less, and even more preferably 3.3 ppm / °C or less. Furthermore, by reducing the average thermal expansion coefficient, the difference in thermal expansion coefficient between the substrate and other components can be more appropriately adjusted when manufacturing a device or the like using the substrate.

[0026] On the other hand, the lower limit is not particularly limited, but is preferably 1.0 ppm / °C or more, more preferably 2.0 ppm / °C or more, in order to obtain thermal properties suitable for molding.

[0027] The thermal expansion coefficient can be adjusted by the content of alkali metal oxides and alkaline earth metal oxides in the composition of the glass that serves as the substrate, and by the thermal history. The average thermal expansion coefficient at 50 to 350° C. can be measured using a differential thermal dilatometer in accordance with the method specified in JIS R3102 (1995).

[0028] By reducing the relative permittivity and dielectric loss tangent of the glass substrate, it is possible to reduce the dielectric loss in the high frequency range.

[0029] The relative dielectric constant at 20°C and 35 GHz is 10 or less, and the dielectric loss tangent (tan δ) is 0.006 or less. The relative dielectric constant is preferably 8 or less, more preferably 6 or less, even more preferably 5 or less, and even more preferably 4.5 or less. There is no particular restriction on the lower limit of the relative dielectric constant, but it is usually 4.0 or more. The dielectric loss tangent is preferably 0.005 or less, more preferably 0.004 or less, even more preferably 0.0035 or less, and even more preferably 0.003 or less. There is no particular restriction on the lower limit of the dielectric loss tangent, but it is usually 0.0005 or more.

[0030] Furthermore, the relative dielectric constant at 20°C and 10 GHz is preferably 10 or less, and the dielectric loss tangent (tan δ) is preferably 0.006 or less. The relative dielectric constant is more preferably 8 or less, even more preferably 6 or less, even more preferably 5 or less, and particularly preferably 4.5 or less. There are no particular restrictions on the lower limits of the relative dielectric constants, but each is usually 4.0 or less. The dielectric loss tangent is more preferably 0.005 or less, even more preferably 0.004 or less, even more preferably 0.0035 or less, and particularly preferably 0.003 or less. There are no particular restrictions on the lower limit of the dielectric loss tangent, but it is usually 0.0005 or more.

[0031] Furthermore, by making the values ​​of the relative permittivity and electrostatic dissipation factor at 20°C and 35 GHz closer to those at 20°C and 10 GHz and reducing the frequency dependency (dielectric dispersion), the frequency characteristics of the dielectric properties are less likely to change, and design changes can be minimized even when the frequency used is different, which is preferable.

[0032] The relative dielectric constant and dielectric loss tangent can be adjusted by the composition of the glass substrate. The relative permittivity and dielectric loss tangent can be measured using a cavity resonator and a vector network analyzer in accordance with the method specified in JIS R1641 (2007).

[0033] Cracks in glass substrates due to thermal shock tend to occur from the edge of the substrate. Therefore, the smaller the surface roughness of the edge of the substrate, the lower the stress concentration and the better the thermal shock resistance. The surface roughness of the edge of the substrate, as expressed as the arithmetic mean roughness Ra, is preferably 1.5 nm or less, more preferably 1.0 nm or less, even more preferably 0.8 nm or less, even more preferably 0.5 nm or less, and particularly preferably 0.3 nm or less. The edge of the glass substrate refers to a surface parallel to the thickness direction of the substrate.

[0034] The arithmetic mean roughness Ra means a value obtained in accordance with JIS B0601 (2001).

[0035] In order to set the surface roughness of the end face within the above range, for example, polishing or etching using a chemical such as hydrofluoric acid may be used.

[0036] The polishing treatment may be, for example, mechanical polishing using an abrasive containing cerium oxide, colloidal silica, or the like as a main component, and a polishing pad, chemical mechanical polishing using an abrasive slurry containing an abrasive, an acidic liquid, or an alkaline liquid as a dispersion medium, and a polishing pad, or chemical polishing using an acidic liquid or an alkaline liquid as an etching liquid, etc. These polishing treatments are applied depending on the surface roughness of the glass plate that is the raw material for the glass substrate, and, for example, preliminary polishing and finish polishing may be applied in combination.

[0037] Furthermore, since substrates are prone to breakage, cracks, chipping, etc. originating from their edges, it is preferable to chamfer at least a portion of the edge to improve the strength of the substrate, and it is more preferable to chamfer the edge at an obtuse angle, as this further improves strength. Examples of chamfering shapes include C-chamfering, R-chamfering, and light chamfering, and chamfering can also be performed in complex shapes that combine these. Of these, C-chamfering and R-chamfering are preferred.

[0038] C-chamfering is a chamfering method in which the corners between the main surface and the edge surface are beveled off, and the angle between the plane perpendicular to the main surface of the substrate and the surface after the corners have been beveled off is preferably 120° or greater, more preferably 135° or greater, and even more preferably 175° or greater.

[0039] R chamfering is a chamfering method in which the shape after chamfering is more rounded than C chamfering.

[0040] The arithmetic mean roughness Ra of the chamfered surface is preferably 0.2 μm or less. "Arithmetic mean roughness Ra" refers to a value measured using a method in accordance with JIS B0601:2001 under the conditions of an evaluation length of 8 mm, a cutoff value λc of 0.8 mm, and a cutoff ratio λc / λs of 100. This makes it less likely that cracks will originate from the chamfered surface. One method for reducing the arithmetic mean roughness Ra of the chamfered surface to 0.2 μm or less is to polish the chamfered surface with a diamond film of #1000 to #3000.

[0041] The main surface of a glass substrate is the surface on which a wiring layer is formed when the substrate is used in, for example, a high-frequency circuit, and the surface roughness of the main surface is preferably 1.5 nm or less in terms of arithmetic mean roughness Ra, because this can reduce the skin resistance of the wiring layer where the skin effect occurs, even in a high-frequency region exceeding 30 GHz, thereby reducing conductor loss. The arithmetic mean roughness Ra of the main surface of the substrate is more preferably 1.0 nm or less, and even more preferably 0.5 nm or less.

[0042] The surface roughness of the main surface can be achieved by subjecting the surface of the main surface to polishing, etc., as required. The polishing method can be the same as that used for polishing the end faces.

[0043] The shape of the substrate is not particularly limited, but the area of ​​one main surface is 100 cm 2 It is preferable that the distance is 225cm or more from the viewpoint of the transmission and reception efficiency of the antenna, etc. 2 More preferably, 100,000 cm 2 It is preferable that the thickness is 10,000 cm or less from the viewpoint of ease of handling of the substrate. 2 Less than 3600cm is more preferable. 2 The following is even more preferred:

[0044] The thickness of the substrate is preferably 0.01 mm or more in terms of maintaining the strength of the substrate, more preferably 0.05 mm or more, and even more preferably 0.1 mm or more in terms of enhancing the ultraviolet shielding ability and protecting the resin that deteriorates due to ultraviolet rays, and even more preferably more than 0.2 mm.

[0045] On the other hand, from the viewpoints of reducing the thickness and size of high-frequency devices and liquid crystal antennas using high-frequency circuits and improving production efficiency, the thickness is preferably 2 mm or less, and more preferably 1 mm or less. Furthermore, from the viewpoints of increasing ultraviolet transmittance and improving manufacturability by using ultraviolet-curable materials in the manufacturing process of devices, antennas, etc., the thickness is even more preferably 0.7 mm or less, and even more preferably 0.5 mm or less.

[0046] The Vickers hardness of the substrate is preferably 400 or more because it is less likely to crack due to mechanical impact, more preferably 450 or more, and even more preferably 500 or more. Also, 550 or less is preferred.

[0047] The Vickers hardness can be adjusted by the composition of the glass in the substrate, and can be measured by a method in accordance with JIS R1310 (2003).

[0048] The crack initiation load of the substrate is preferably more than 1.96 N, more preferably 4.9 N or more, even more preferably 9.8 N or more, and particularly preferably more than 19.6 N, in order to make the substrate less susceptible to cracking due to mechanical impact.

[0049] The crack initiation load can be adjusted by the glass composition, thermal history, and surface treatment of the substrate, and can be determined by measuring the load at which the crack initiation rate exceeds 50% using a Vickers hardness tester.

[0050] The density of the substrate is set to 2.5 g / cm in order to reduce the weight of devices and antennas that use the substrate, and to reduce the brittleness of the glass, making it less susceptible to cracking due to thermal shock or mechanical shock. 3Less than 2.4 g / cm is preferred 3 Less than 2.35 g / cm is more preferable. 3 More preferably, 2.3 g / cm 3 The lower limit is not particularly limited, but is usually 2.0 g / cm 3 That's it. Density can be measured by Archimedes' method.

[0051] It is preferable that at least one of the main surfaces of the substrate has a compressive stress layer on at least a portion of the surface in order to make it less susceptible to cracking due to thermal shock or mechanical shock. The compressive stress layer can be formed, for example, by a strengthening treatment, and either a physical strengthening treatment or a chemical strengthening treatment can be used. For both the physical strengthening treatment and the chemical strengthening treatment, a conventionally known method can be used.

[0052] The porosity of the substrate is preferably 0.1% or less, more preferably 0.01% or less, and even more preferably 0.001% or less, from the viewpoint of suppressing noise generation when fabricating a high-frequency device, and is preferably 0.0001% or less from the viewpoint of a liquid crystal antenna, in order to suppress the occurrence of wiring defects due to open pores exposed on the surface.

[0053] The porosity can be determined by observing bubbles contained in the glass substrate with an optical microscope, determining the number and diameter of the bubbles, and calculating the volume of the bubbles contained per unit volume.

[0054] The transmittance of the substrate for light with a wavelength of 350 nm is preferably 50% or more, as this allows for the use of ultraviolet-curable materials in lamination processes and other processes in the manufacturing process of high-frequency devices, antennas, etc., thereby improving manufacturability. Furthermore, 70% or more is more preferable in order to shorten the ultraviolet irradiation time of the ultraviolet-curable material in the manufacturing process of devices, antennas, etc., and reduce uneven curing of the ultraviolet-curable material in the thickness direction.

[0055] For the same reasons as above, the transmittance of the substrate for light with a wavelength of 300 nm is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more, and the transmittance of light with a wavelength of 250 nm is preferably 5% or more, more preferably 10% or more, and even more preferably 20% or more.

[0056] On the other hand, when a resin that deteriorates due to ultraviolet rays is used as a component in a device, antenna, etc., in order to give the substrate ultraviolet shielding ability and the function as a protective material, the transmittance of light with a wavelength of 350 nm is preferably 80% or less, more preferably 60% or less, even more preferably 30% or less, and most preferably 10% or less.

[0057] For the same reasons as above, the transmittance of the substrate for light with a wavelength of 300 nm is preferably 80% or less, more preferably 60% or less, even more preferably 30% or less, and even more preferably 10% or less. Also, the transmittance of light with a wavelength of 250 nm is preferably 60% or less, more preferably 30% or less, even more preferably 10% or less, and even more preferably 5% or less.

[0058] The transmittance of light of each wavelength of the substrate can be measured using a visible-ultraviolet spectrophotometer, and the external transmittance including loss due to reflection is used.

[0059] The β-OH value of the substrate is a value used as an index of the water content of the glass. The absorbance of the glass substrate for light with a wavelength of 2.75 to 2.95 μm is measured, and the maximum value β max This value is calculated by dividing by the thickness of the substrate (mm).

[0060] β-OH value is 0.8mm -1 By setting the thickness to 0.6 mm or less, the low dielectric loss of the substrate can be further improved, and this is preferable. -1 Less than 0.5mm is preferable -1 Less than 0.4 mm is more preferable. -1 Even more preferred are the following:

[0061] On the other hand, the β-OH value is 0.05 mm-1 By setting the β-OH value at 0.1 mm or more, it is not necessary to dissolve the glass in an extremely dry atmosphere or to drastically reduce the amount of water in the raw materials, and this is preferable because it is possible to improve the productivity of the glass and the bubble quality. -1 More preferably, 0.2 mm or more -1 The above is even more preferable.

[0062] The β-OH value can be adjusted by the composition of the glass in the substrate, the heat source during melting, the melting time, and the raw materials.

[0063] The devitrification temperature of the substrate is preferably 1400°C or lower. If the devitrification temperature is 1400°C or lower, the temperature of the components of the forming equipment can be lowered when forming the glass, thereby extending the life of the components. The devitrification temperature is more preferably 1350°C or lower, even more preferably 1330°C or lower, and particularly preferably 1300°C or lower.

[0064] The devitrification temperature of glass is the average of the maximum temperature at which crystals precipitate on the surface and inside of the glass and the minimum temperature at which crystals do not precipitate when crushed glass particles are placed in a platinum dish and heat-treated for 17 hours in an electric furnace controlled at a constant temperature and the sample is observed under an optical microscope after heat treatment.

[0065] The glass in the substrate refers to an amorphous solid that exhibits glass transition. It does not include crystallized glass, which is a mixture of glass and crystal, or sintered glass containing a crystalline filler. The crystallinity of glass can be confirmed by, for example, X-ray diffraction measurement, and the absence of clear diffraction peaks to confirm that the glass is amorphous.

[0066] The glass substrate is formed by melting and hardening a glass raw material, the details of which will be described later. The method for manufacturing the substrate is not particularly limited, but for example, a method can be applied in which a general molten glass is formed into a plate with a predetermined thickness by a float method, and then slowly cooled and cut into a desired shape to obtain a plate glass.

[0067] The glass composition of the substrate will be described below. In this specification, "substantially free" means that no impurities other than those unavoidable from raw materials, etc., are contained, that is, no impurities are intentionally contained, and the content is generally 0.1 mol % or less, but is not limited to this.

[0068] The glass preferably contains SiO2 as a major component. In this specification, "containing SiO2 as a major component" means that the SiO2 content is the largest in terms of the proportion of components in mole percent based on oxides. SiO2 is a network-forming substance, and its content is preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and particularly preferably 55% or more, because it can improve glass-forming ability and weather resistance and suppress devitrification. On the other hand, in terms of improving the meltability of the glass, its content is preferably 75% or less, more preferably 74% or less, even more preferably 73% or less, and even more preferably 72% or less.

[0069] The total content of Al2O3 and B2O3 (including the case where the Al2O3 content is 0) is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, and even more preferably 7% or more, because this can improve the meltability of the glass, etc. Furthermore, the total content of Al2O3 and B2O3 is preferably 40% or less, more preferably 37% or less, even more preferably 35% or less, and even more preferably 33% or less, because this can improve the low dielectric loss properties of the substrate while maintaining the meltability of the glass, etc.

[0070] The molar ratio of the content expressed by {Al2O3 / (Al2O3+B2O3)} is preferably 0.45 or less, more preferably 0.4 or less, and even more preferably 0.3 or less, because this can improve the low dielectric loss of the glass substrate. The molar ratio of the content expressed by {Al2O3 / (Al2O3+B2O3)} is preferably 0 or more (including 0), more preferably 0.01 or more, and even more preferably 0.05 or more.

[0071] The content of Al2O3 is preferably 15% or less, more preferably 14% or less, and even more preferably 10% or less, because it can improve the melting property of the glass, etc. Furthermore, since Al2O3 is a component that is effective in improving weather resistance, suppressing phase separation of the glass, and reducing the thermal expansion coefficient, etc., it does not have to be contained, but if it is contained, the content is more preferably 0.5% or more.

[0072] The content of B2O3 is preferably 30% or less, more preferably 28% or less, even more preferably 26% or less, even more preferably 24% or less, and particularly preferably 23% or less, because it can improve acid resistance and strain point. Also, because B2O3 is a component that is effective in improving the melt reactivity and lowering the devitrification temperature, the content of B2O3 is preferably 9% or more, more preferably 13% or more, and even more preferably 16% or more.

[0073] Examples of alkaline earth metal oxides include MgO, CaO, SrO, and BaO, all of which function as components that enhance the melting reactivity of glass. The total content of these alkaline earth metal oxides is preferably 13% or less, more preferably 11% or less, even more preferably 10% or less, even more preferably 8% or less, and particularly preferably 6% or less, because it can improve the low dielectric loss of the glass substrate. Furthermore, the total content of alkaline earth metal oxides is preferably 0.1% or more, more preferably 3% or more, and even more preferably 5% or more, because it can maintain good glass melting properties.

[0074] Although MgO is not an essential component, it is a component that can increase the Young's modulus without increasing the specific gravity. In other words, MgO is a component that can increase the specific elastic modulus, and by including MgO, the problem of deflection can be alleviated, and the fracture toughness value can be improved, thereby increasing the glass strength. MgO is also a component that improves solubility. Although MgO is not an essential component, the effect of including MgO can be fully obtained and the thermal expansion coefficient can be prevented from becoming too low. Therefore, the content is preferably 0.1% or more, more preferably 1% or more, and even more preferably 3% or more. On the other hand, in order to prevent an increase in the devitrification temperature, the MgO content is preferably 13% or less, more preferably 11% or less, and even more preferably 9% or less.

[0075] Among alkaline earth metals, CaO is the component that increases the specific modulus second only to MgO and does not excessively lower the strain point, and like MgO, it also improves solubility. Furthermore, compared to MgO, CaO is also characterized by its tendency to raise the devitrification temperature less. Although CaO is not an essential component, its content is preferably 0.1% or more, more preferably 1% or more, and even more preferably 3% or more, because the effect of including CaO can be fully obtained. Furthermore, the CaO content is preferably 13% or less, more preferably 10% or less, and even more preferably 8% or less, so that the average thermal expansion coefficient does not become too high and the increase in the devitrification temperature can be suppressed, thereby preventing devitrification during glass production.

[0076] SrO is a component that improves the meltability of glass without increasing the devitrification temperature. Although SrO is not an essential component, the effect of including SrO can be fully obtained, so its content is preferably 0.1% or more, more preferably 0.5% or more, even more preferably 1% or more, even more preferably 1.5% or more, and particularly preferably 2% or more. Furthermore, in order to prevent the specific gravity from becoming too high and to prevent the average thermal expansion coefficient from becoming too high, the SrO content is preferably 13% or less, more preferably 10% or less, even more preferably 7% or less, and particularly preferably 5% or less.

[0077] Although BaO is not an essential component, it does not increase the devitrification temperature of glass and improves its melting point. However, a large amount of BaO tends to increase the specific gravity, decrease the Young's modulus, increase the dielectric constant, and increase the average thermal expansion coefficient too much. Therefore, the BaO content is preferably 10% or less, more preferably 8% or less, even more preferably 5% or less, even more preferably 3% or less, and particularly preferably substantially none.

[0078] If the value represented by the following formula 1 using the contents of the above components of the glass is 300 or less, even if distortion occurs due to a difference in thermal expansion, the stress on the substrate will be small, and thermal shock resistance will be improved, so this is preferable, 280 or less is more preferable, 250 or less is even more preferable, 220 or less is even more preferable, and 200 or less is particularly preferable. There is no particular lower limit, but from the viewpoint of obtaining thermal properties suitable for molding, 100 or more is preferable.

[0079] (1.02×SiO2+3.42×Al2O3+0.74×B2O3+9.17×MgO+12.55×CaO+13.85×SrO+14.44×BaO+31.61×Na2O+20.35×K2O) ··· Formula 1

[0080] Examples of alkali metal oxides include Li2O, Na2O, KO, Rb2O, and Cs2O. The total content of such alkali metal oxides is preferably 5% or less, more preferably 3% or less, even more preferably 1% or less, even more preferably 0.2% or less, particularly preferably 0.1% or less, and most preferably 0.05% or less, from the viewpoint of improving the low dielectric loss of the glass substrate. Furthermore, since excessive raw material purification is not required, practical glass meltability and glass substrate productivity are obtained, and the thermal expansion coefficient of the glass substrate can be adjusted, the content is preferably 0.001% or more, more preferably 0.002% or more, even more preferably 0.003% or more, and even more preferably 0.005% or more.

[0081] Among the above alkali metal oxides, Na2O and K2O are particularly important, and the total content of Na2O and K2O is preferably in the range of 0.001 to 5%.

[0082] Furthermore, the coexistence of Na2O and K2O is preferable because it suppresses the migration of alkali components and thereby improves the low dielectric loss of the glass substrate. That is, the molar ratio of the content expressed as {Na2O / (Na2O+K2O)} is preferably 0.01 to 0.99, more preferably 0.98 or less, even more preferably 0.95 or less, and even more preferably 0.9 or less. On the other hand, the molar ratio of the content expressed as {Na2O / (Na2O+K2O)} is more preferably 0.02 or more, even more preferably 0.05 or more, and even more preferably 0.1 or more.

[0083] In addition to the above components, optional components such as Fe2O3, TiO2, ZrO2, ZnO, Ta2O5, WO3, Y2O3, and La2O3 may be included. Among these, Fe2O3 is a component that controls the light absorption performance, such as infrared absorption and ultraviolet absorption performance, of the glass substrate. If necessary, the Fe content, calculated as Fe2O3, can be up to 0.012% or less. If the Fe content is 0.012% or less, the low dielectric loss and ultraviolet transmittance of the glass substrate can be maintained. When Fe is included, its content is preferably 0.01% or less, and even more preferably 0.005% or less, in order to improve ultraviolet transmittance. Increasing the ultraviolet transmittance of the glass substrate allows the use of ultraviolet-curable materials in lamination processes and other processes in the manufacturing process of high-frequency devices, antennas, and the like, thereby improving the manufacturability of high-frequency devices, antennas, and the like.

[0084] On the other hand, it is also preferable that the glass substrate contains 0.05% or more Fe in terms of Fe2O3, as needed, in order to enhance the ultraviolet shielding ability. The Fe content is more preferably 0.07% or more, and even more preferably 0.1% or more. In this way, by enhancing the ultraviolet shielding ability of the glass substrate, the glass substrate can be endowed with the function of a protective material when a resin that deteriorates under ultraviolet light is used as a component.

[0085] <Glass substrate manufacturing method> The method for producing a glass substrate includes a melting step of heating glass raw materials to obtain molten glass, a fining step of removing bubbles from the molten glass, a forming step of forming the molten glass into a plate to obtain a glass ribbon, and an annealing step of annealing the glass ribbon to room temperature. Alternatively, the glass substrate may be produced by forming the molten glass into a block, annealing it, and then cutting and polishing it.

[0086] In the melting step, raw materials are prepared to have the desired composition of the glass substrate, and the raw materials are continuously charged into a melting furnace and heated preferably to about 1450°C to 1750°C to obtain molten glass.

[0087] Halides such as oxides, carbonates, nitrates, hydroxides, and chlorides can also be used as raw materials. If the molten glass comes into contact with platinum during the melting or fining process, minute platinum particles may dissolve into the molten glass and become contaminated as foreign matter in the resulting glass substrate. However, the use of a nitrate raw material has the effect of preventing the generation of platinum foreign matter.

[0088] As the nitrate, strontium nitrate, barium nitrate, magnesium nitrate, calcium nitrate, etc. can be used. It is more preferable to use strontium nitrate. The particle size of the raw material can be appropriately selected from raw materials with a particle size of several hundred μm, which is large enough to prevent residual dissolution, to raw materials with a particle size of about several μm, which is small enough not to scatter during raw material transportation and not to aggregate as secondary particles. Granules can also be used.

[0089] The moisture content of the raw material can be adjusted appropriately to prevent scattering of the raw material. 2+ / (Fe 2+ +Fe 3+ )) can also be used by adjusting the dissolution conditions as appropriate.

[0090] The fining step is a step of removing bubbles from the molten glass obtained in the melting step. The fining step may be performed by degassing under reduced pressure, or by heating the temperature higher than the melting temperature of the raw materials. In the manufacturing process of the glass substrate according to the embodiment, SO or SnO may be used as a fining agent. As the SO3 source, a sulfate of at least one element selected from the group consisting of Al, Na, K, Mg, Ca, Sr, and Ba is preferred, and an alkaline earth metal sulfate is more preferred. Among these, CaSO4·2H2O, SrSO4, and BaSO4 are particularly preferred because they have a significant effect of increasing bubble size.

[0091] As a fining agent in the degassing method under reduced pressure, a halogen such as Cl or F is preferably used.

[0092] The Cl source is preferably a chloride of at least one element selected from the group consisting of Al, Mg, Ca, Sr, and Ba, and more preferably an alkaline earth metal chloride. Among these, SrCl2·6H2O and BaCl2·2H2O are particularly preferred because they have a significant effect of increasing bubble size and are less prone to deliquescence.

[0093] The F source is preferably a fluoride of at least one element selected from the group consisting of Al, Na, K, Mg, Ca, Sr, and Ba, more preferably an alkaline earth metal fluoride, and among these, CaF is more preferred because it has a significant effect of increasing the solubility of the glass raw materials.

[0094] Tin compounds, such as SnO2, generate O2 gas in molten glass. In the molten glass, SnO2 is reduced to SnO at temperatures of 1450°C or higher, generating O2 gas and causing bubbles to grow larger. In the production of the glass substrate of the embodiment, the glass raw material is heated to approximately 1450 to 1750°C to melt, which effectively increases the size of bubbles in the molten glass.

[0095] When SnO2 is used as a fining agent, the tin compound in the raw materials is adjusted to contain 0.01% or more of the tin compound calculated as SnO2 relative to 100% of the total amount of the matrix composition. A SnO2 content of 0.01% or more is preferable because it provides a fining effect during melting of the glass raw materials, more preferably 0.05% or more, and even more preferably 0.10% or more. On the other hand, a SnO2 content of 0.3% or less is preferable because it suppresses the occurrence of coloration and devitrification of the glass. The content of the tin compound in the alkali-free glass is more preferably 0.25% or less, more preferably 0.2% or less, and particularly preferably 0.15% or less, calculated as SnO2 relative to 100% of the total amount of the matrix composition.

[0096] The forming step is a step of forming the molten glass from which bubbles have been removed in the fining step into a sheet to obtain a glass ribbon. As the forming step, a known method for forming glass into a sheet can be applied, such as a float method in which molten glass is poured onto a molten metal such as tin to form a sheet and obtain a glass ribbon, an overflow downdraw method (fusion method) in which molten glass is made to flow downward from a trough-shaped member, or a slit downdraw method in which molten glass is made to flow down through a slit.

[0097] The annealing process is a process in which the glass ribbon obtained in the forming process is cooled to room temperature under controlled cooling conditions. In the annealing process, the glass ribbon is cooled to a temperature range between the annealing point and the strain point of the formed glass at a predetermined average cooling rate, R (°C / min), and then further annealed to room temperature under predetermined conditions. The annealed glass ribbon is cut to obtain a glass substrate.

[0098] The predetermined average cooling rate R [cooling rate (R)] will be explained below.

[0099] If the cooling rate (R) in the slow cooling step is too high, distortion tends to remain in the cooled glass. Furthermore, the equivalent cooling rate, which is a parameter that reflects the fictive temperature, becomes too high, resulting in failure to obtain low dielectric loss characteristics. Therefore, it is preferable to set R so that the equivalent cooling rate is 800°C / min or less. The equivalent cooling rate is more preferably 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 process time required becomes too long, resulting in low productivity. Therefore, it is preferable to set R to 0.1°C / min or more, more preferably 0.5°C / min or more, and even more preferably 1°C / min or more.

[0100] Here, the definition and evaluation method of the equivalent cooling rate are as follows.

[0101] Glass of the target composition is processed into a rectangular parallelepiped of 10 mm x 10 mm x 0.3 to 2.0 mm. It is heated in an infrared heating electric furnace at strain point +170°C for 5 minutes, and then cooled to room temperature (25°C). At this time, multiple glass samples are produced by varying the cooling rate between 1°C / min and 1000°C / min.

[0102] Using a precision refractive index measuring device (e.g., Shimadzu Devices KPR2000), the refractive index n of multiple glass samples at the d line (wavelength 587.6 nm) was measured. d The V-block method or the minimum deviation method may be used for the measurement. d is plotted against the logarithm of the cooling rate, the n d Obtain a calibration curve.

[0103] Next, we compared the n of glasses with the same composition that were actually manufactured through processes such as melting, molding, and cooling. d is measured by the above-mentioned measurement method. dThe corresponding cooling rate (referred to as an equivalent cooling rate in this embodiment) is determined from the calibration curve.

[0104] Although the method for manufacturing a glass substrate has been described above, the manufacturing method is not limited to the above embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. For example, when manufacturing the glass substrate of the present invention, glass may be formed into a plate shape by a press molding method in which molten glass is directly formed into a plate shape.

[0105] Furthermore, when producing the glass substrate of the present invention, in addition to the production method using a refractory melting tank, a crucible made of platinum or an alloy containing platinum as a main component (hereinafter referred to as a platinum crucible) may be used as the melting tank or refining tank. When a platinum crucible is used, the melting step involves preparing raw materials so as to obtain the composition of the glass substrate to be obtained, and heating the platinum crucible containing the raw materials in an electric furnace, preferably to about 1450°C to 1700°C. A platinum stirrer is inserted and the mixture is stirred for 1 to 3 hours to obtain molten glass.

[0106] In the forming process of glass plate manufacturing using a platinum crucible, molten glass is poured onto, for example, a carbon plate or a mold and formed into a plate or block. The slow cooling process typically involves maintaining the glass at a temperature of approximately Tg+50°C relative to the glass transition point (Tg), then cooling to near the strain point at a rate of approximately 1 to 10°C / min, and then cooling to room temperature at a cooling rate sufficient to prevent residual distortion. After cutting and polishing to a predetermined shape, a glass substrate is obtained. Alternatively, the glass substrate obtained by cutting may be heated to, for example, approximately Tg+50°C, and then slowly cooled to room temperature at a predetermined cooling rate. This allows the equivalent cooling temperature of the glass to be adjusted.

[0107] <High frequency circuits, LCD antennas> The glass substrate of the present invention is suitable for circuit boards of high-frequency devices (electronic devices) such as semiconductor devices used in communication devices such as mobile phones, smartphones, personal digital assistants, and Wi-Fi devices, surface acoustic wave (SAW) devices, radar components such as radar transceivers, and antenna components such as liquid crystal antennas. In particular, the glass substrate of the present invention can reduce the dielectric loss of high-frequency signals and has excellent thermal shock resistance, making it even more suitable for high-frequency circuits used in high-frequency devices and liquid crystal antenna substrates.

[0108] As a substrate for high-frequency circuits, it is particularly suitable for high-frequency devices that handle high-frequency signals, particularly high-frequency signals exceeding 30 GHz, and even high-frequency signals of 35 GHz or higher, and can reduce the transmission loss of such high-frequency signals and improve the characteristics of the high-frequency signals, such as their quality and strength.

[0109] It is also suitable as a substrate for drilling holes using a laser or the like, and not only improves the aforementioned characteristics such as the quality and strength of high frequency signals, but also has high resistance to thermal shock when drilling holes.

[0110] FIG. 1 shows an example (cross-sectional view) of the configuration of a high-frequency circuit used in a high-frequency device. The circuit board 1 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 and second wiring layers 3 and 4 form a microstrip line as an example of a transmission line. The first wiring layer 3 forms a signal line, and the second wiring layer 4 forms a ground line. However, the structure of the first and second wiring layers 3 and 4 is not limited to this, and the wiring layers may be formed on only one of the main surfaces of the glass substrate 2.

[0111] The first and second wiring layers 3 and 4 are layers formed of a conductor, and their thickness is usually about 0.1 to 50 μm.

[0112] The conductors forming the first and second wiring layers 3 and 4 are not particularly limited, and may be metals such as copper, gold, silver, aluminum, titanium, chromium, molybdenum, tungsten, platinum, nickel, alloys or metal compounds containing at least one of these metals.

[0113] The structure of the first and second wiring layers 3, 4 is not limited to a single layer structure, and may be 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, 4 is not particularly limited, and various known forming methods can be applied, such as a printing method using a conductive paste, a dipping method, a plating method, a vapor deposition method, and a sputtering method.

[0114] By using the glass substrate of the present invention in a high-frequency circuit, the transmission loss of the circuit board at high frequencies can be reduced. Specifically, for example, the transmission loss at a frequency of 35 GHz can be reduced to preferably 1 dB / cm or less, more preferably 0.5 dB / cm or less. Therefore, the characteristics such as the quality and strength of high-frequency signals, particularly high-frequency signals exceeding 30 GHz, and even high-frequency signals of 35 GHz or higher, are maintained, and a glass substrate and circuit board suitable for high-frequency devices handling such high-frequency signals can be provided. This can improve the characteristics and quality of high-frequency devices handling high-frequency signals.

[0115] High-frequency circuit boards also include substrates known as universal boards or perforated boards, which have through-holes and copper foil lands formed in a regular pattern (such as a grid) in an insulating base plate, and copper foil wiring connecting several of the lands formed by etching. Lasers are used to form the through-holes and perform the etching, and examples of such lasers include excimer lasers, infrared lasers, CO2 lasers, and UV lasers.

[0116] When forming through holes or performing etching, a temperature difference occurs within the glass substrate, causing thermal shock. However, the glass substrate of the present invention has high thermal shock resistance, and therefore, through holes or etching can be formed without cracking even in the face of the thermal shock.

[0117] An LCD antenna is a satellite communication antenna that uses liquid crystal technology to control the direction of radio waves it transmits and receives, and is primarily suitable for use on vehicles such as ships, airplanes, and automobiles. Because LCD antennas are primarily intended for outdoor use, they must have stable characteristics over a wide temperature range, and must also be resistant to thermal shock caused by sudden temperature changes, such as between the ground and the sky, or during a rain shower in a scorching desert.

[0118] By using the glass substrate of the present invention for a liquid crystal antenna, stable characteristics can be provided over a wide temperature range, and further, since it has resistance to sudden temperature changes, it can be used without breaking, which is preferable. [Example]

[0119] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0120] [Examples 1-26] Glass substrates with the compositions shown in Tables 1 to 4, thicknesses of 0.5 to 10 mm, and dimensions of 50 × 50 mm were prepared. The glass substrates were fabricated by a melting method using a platinum crucible. Raw materials such as silica sand were mixed to obtain 1 kg of glass, and a batch was prepared. To 100% of the raw materials of the target composition, 0.1% to 1% of sulfate (calculated as SO3), 0.16% of F, and 1% of Cl were added, expressed as mass percentages based on oxides. The raw materials were placed in a platinum crucible and melted in an electric furnace at 1650°C for 3 hours to produce molten glass.

[0121] The melting was performed in a platinum crucible with a platinum stirrer for 1 hour to homogenize the glass. The molten glass was poured onto a carbon plate and formed into a plate. The plate was then placed in an electric furnace at a temperature of approximately Tg + 50°C and held there for 1 hour. The furnace was then cooled to Tg - 100°C at a rate of 1°C / min, and the glass was then allowed to cool to room temperature.

[0122] The glass was then cut and polished to form a plate. The edge was then chamfered (C / R) using a chamfering device. An example of a glass plate chamfering device is the device described in Japanese Patent Application Laid-Open Publication No. 2008-49449, which uses a rotating grindstone to chamfer the edge of the glass plate. The rotating grindstone may be either resin-bonded or metal-bonded. Examples of abrasive grains used in the grindstone include diamond, cubic boron nitride (CBN), alumina (Al2O3), silicon carbide (SiC), pumice, garnet, or a combination thereof.

[0123] In Tables 1 to 4, the total amount of RO *1 indicates the total content of alkaline earth metal oxides (MgO + CaO + SrO + BaO), and the total amount of R2O *2 represents the total content of alkali metal oxides (Na2O + K2O).

[0124] The obtained glass substrates were measured for the following: Formula 1, Young's modulus, average thermal expansion coefficient at 50 to 350°C, Formula 2, relative dielectric constant (20°C) at 10 GHz and 35 GHz, dielectric loss tangent (20°C) at 10 GHz and 35 GHz, Vickers hardness, crack initiation load, density, specific elastic modulus, porosity, transmittance of light with a wavelength of 350 nm (converted into a thickness of 0.3 to 0.4 mm), β-OH value, and devitrification temperature.

[0125] Equation 1 is a value expressed as {1.02 × SiO2 + 3.42 × Al2O3 + 0.74 × B2O3 + 9.17 × MgO + 12.55 × CaO + 13.85 × SrO + 14.44 × BaO + 31.61 × Na2O + 20.35 × K2O} using the content expressed in mole percentage on an oxide basis.

[0126] Equation 2 is a value expressed as {Young's modulus (GPa)×average thermal expansion coefficient at 50 to 350° C. (ppm / ° C.)}.

[0127] The values ​​of Formula 1 are shown in Tables 1 to 4, and other results are shown in Tables 5 to 8. Note that the values ​​in parentheses in the tables were determined by calculation, and blank spaces or - indicate that the value was not measured.

[0128] The methods for measuring each physical property are shown below.

[0129] (Young's modulus) Measurements were carried out on glass with a thickness of 0.5 to 10 mm using an ultrasonic pulse method in accordance with the method specified in JIS Z 2280. The unit of measurement was GPa.

[0130] (average thermal expansion coefficient) Measurements were made using a differential thermal dilatometer in accordance with the method specified in JIS R3102 (1995). The measurement temperature range was 50 to 350°C, and the unit was expressed as ppm / °C.

[0131] (relative permittivity, dielectric loss tangent) Measurements were performed using a cavity resonator and a vector network analyzer according to the method specified in JIS R1641 (2007). The measurement frequencies were 35 GHz and 10 GHz, which are the air resonance frequencies of the cavity resonator.

[0132] (Vickers hardness) The Vickers hardness of the glass was measured at a load of 100 gf according to the method specified in JIS R1610 (2003).

[0133] (Crack initiation load) This is the indentation load at which, when a square pyramidal Vickers indenter (diamond indenter) is pressed into a glass surface for 30 seconds in an atmosphere with a relative humidity of approximately 40%, 50% of the time a crack forms outward from all four corners of the indentation. The crack initiation load can be measured using a commercially available Vickers hardness tester. The crack initiation load is the average value for 10 or more indentations.

[0134] (density) The density of a glass block weighing approximately 20 g and containing no bubbles was measured by Archimedes' method, and the unit was expressed as g / cm. 3 It was expressed as:

[0135] (Porosity) The bubbles contained in the glass substrate were observed under an optical microscope, and the number and diameter of the bubbles were determined, and the volume of the bubbles contained per unit volume was calculated.

[0136] (transmittance) The transmittance of mirror-polished glass of a specified thickness was measured using a visible-ultraviolet spectrophotometer. The transmittance was defined as the external transmittance including loss due to reflection, and was expressed as a value converted into a glass thickness of 0.3 to 0.4 mm.

[0137] (β-OH value) The measurement was performed using the method described in the above embodiment. The unit is mm -1 It was expressed as:

[0138] (specific elastic modulus) The specific elastic modulus is calculated using the density and Young's modulus measurements, and is expressed in GPa cm. 3 Expressed as / g.

[0139] (devitrification temperature) Crushed glass particles were placed in a platinum dish and heat-treated for 17 hours in an electric furnace controlled at a constant temperature. After heat treatment, the sample was observed under an optical microscope to determine the average value of the maximum temperature at which crystals precipitated inside the glass and the minimum temperature at which crystals did not precipitate.

[0140] [Table 1]

[0141] [Table 2]

[0142] [Table 3]

[0143] [Table 4]

[0144] [Table 5]

[0145] [Table 6]

[0146] [Table 7]

[0147] [Table 8]

[0148] As shown in Tables 5 to 8, the glass substrate of the present invention has a small product of the thermal expansion coefficient and Young's modulus (the value expressed by Equation 2) of 300 or less, and therefore is less likely to generate tensile stress even when a sudden temperature change occurs. As a result, when used in an environment where a sudden temperature change occurs, breakage can be suppressed during processing steps where temperature changes are likely to occur.

[0149] Furthermore, the glass substrate of the present invention has a relative dielectric constant of 10 or less at 20° C. and 35 GHz and a dielectric loss tangent of 0.006 or less at 20° C. and 35 GHz, thereby reducing dielectric loss in the high frequency range.

[0150] Furthermore, when the glass substrate of the present invention is used, since the Vickers hardness is small, processing can be performed with a light load, and since the crack initiation load is large, defects such as microcracks are unlikely to occur, resulting in a substrate with high strength.

[0151] Although the present invention has been described in detail 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 present invention. This application is based on a Japanese patent application (Patent Application No. 2018-53082) filed on March 20, 2018, the entirety of which is incorporated by reference. All references cited herein are incorporated in their entirety. [Industrial Applicability]

[0152] The glass substrate of the present invention has excellent dielectric loss properties for high-frequency signals and exhibits high thermal shock resistance, and therefore, a circuit board using the glass substrate has excellent transmission loss properties for high-frequency signals and is also excellent in processability using heat such as a laser.

[0153] Such glass substrates and circuit boards are extremely useful as components for high-frequency electronic devices in general that handle high-frequency signals exceeding 10 GHz, particularly high-frequency signals exceeding 30 GHz, and even high-frequency signals of 35 GHz or higher, liquid crystal antennas used in environments with large temperature changes, devices that involve hole drilling using a laser or the like, and the like. [Explanation of symbols]

[0154] 1 circuit board 2. Glass substrate 2a First main surface 2b second main surface 3 First wiring layer 4 Second wiring layer

Claims

1. The relationship of {Young's modulus (GPa) × average thermal expansion coefficient at 50 to 350°C (ppm / °C)} ≦ 300 (GPa ppm / °C) is satisfied, The dielectric constant at 20°C and 35 GHz is 10 or less, The dielectric loss tangent at 20°C and 35 GHz is 0.006 or less, The relative dielectric constant at 20°C and 10 GHz is 10 or less, and A glass substrate having a dielectric loss tangent of 0.006 or less at 20°C and 10 GHz, In mole percentage based on oxides, SiO ２ 58 to 75% B ２ O ３ 14 to 30%, CaO 0 to 8%, Contains 0.1 to 10% SrO, {Na ２ O / (Na ２ O+K ２ O)) is 0.62 to 0.99, β-OH value: 0.05 to 0.8 mm －１ and A glass substrate having a Vickers hardness of 400 to 550.

2. 2. The glass substrate according to claim 1, having a Young's modulus of 70 GPa or less.

3. 3. The glass substrate according to claim 1, wherein the average thermal expansion coefficient at 50 to 350° C. is 5 ppm / ° C. or less.

4. The area of ​​the main surface is 100 to 100,000 cm ２ 4. The glass substrate according to claim 1, wherein the glass substrate has a thickness of 0.01 to 2 mm.

5. 5. The glass substrate according to claim 1, wherein at least a part of the end face is chamfered.

6. 6. The glass substrate according to claim 1, wherein the crack initiation load exceeds 1.96 N.

7. Density is 2.5 g / cm ３ 7. The glass substrate according to claim 1, wherein:

8. 8. The glass substrate according to claim 1, wherein the glass substrate has a compressive stress layer on at least a part of the surface of the main surface.

9. 9. The glass substrate according to claim 1, which has a porosity of 0.1% or less.

10. 10. The glass substrate according to claim 1, which has a transmittance of 50% or more for light with a wavelength of 350 nm.

11. In mole percentage based on oxides, Al ２ O ３ and B ２ O ３ Contains a total of more than 14% and not more than 40% {Al ２ O ３ / (Al ２ O ３ +B ２ O ３ )) is 0.01 to 0.42, and 11. The glass substrate according to claim 1, which contains alkaline earth metal oxides in a total amount of 0.1 to 13%.

12. 12. The glass substrate according to claim 1, which contains, in terms of mole percentage based on oxides, 0.001 to 5% in total of alkali metal oxides.

13. In mole percentage based on oxides, Contains 1 to 13% MgO, (1.02 × SiO ２ +3.42 x Al ２ O ３ +0.74 x B ２ O ３ + 9.17 × MgO + 12.55 × CaO + 13.85 × SrO + 14.44 × BaO + 31.61 × Na ２ O + 20.35 x K ２ 13. The glass substrate according to claim 1, wherein the relationship of (O)≦300 is satisfied.

14. In terms of mole percentage based on oxide, Al ２ O ３ The glass substrate according to any one of claims 1 to 13, containing 0.5 to 10% of

15. In terms of mole percentage based on oxide, Fe is Fe ２ O ３ The glass substrate according to any one of claims 1 to 14, wherein the content is 0 to 0.012% in terms of Cr.

16. The glass substrate according to any one of claims 1 to 15, which is used for a liquid crystal antenna or a high-frequency circuit.

17. A liquid crystal antenna comprising the glass substrate according to any one of claims 1 to 15.

18. A high frequency device comprising the glass substrate according to any one of claims 1 to 15.

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