Glass substrate, liquid crystal antenna, and high-frequency device

Abstract

To provide a glass substrate capable of reducing dielectric loss of high-frequency signals and excellent in thermal shock resistance.SOLUTION: The present invention relates to a glass substrate that satisfies the relation of {(Young's modulus (GPa)×(average thermal expansion coefficient at 50-350°C (ppm / °C))}≤300 (GPa ppm / °C), has a relative dielectric constant at 20°C and 35 GHz of 10 or less, and has a dielectric tangent at 20°C and 35 GHz of 0.006 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In electronic devices such as communication devices such as mobile phones, smartphones, personal digital assistants, and Wi-Fi devices, surface acoustic wave (SAW) devices, radar components, and antenna components, signal frequencies are becoming higher in order to increase communication capacity and speed. Insulating substrates such as resin substrates, ceramic substrates, and glass substrates are generally used for circuit boards used in such high-frequency communication devices and electronic devices. 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 an insulating substrate and the wiring width and surface roughness of a wiring layer within specific ranges, it is possible to maintain transmission loss at conventional levels and suppress crosstalk noise. Patent Document 2 discloses that by using lead-free glass having a specific composition, an electronic circuit board with a small relative dielectric constant or dielectric loss can be obtained.

[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 smoothness of the surface of ceramic substrates, which has the drawback that conductor loss caused by the conductor formed on the substrate surface is likely to increase.

[0005] On the other hand, glass substrates have the following characteristics: they are highly rigid, which makes it easy to make packages smaller and thinner; they also have excellent surface smoothness; and the substrate itself can easily be made large.

[0006] In addition, with the spread of IoT, various devices are now equipped with communication functions, and there is a need to install communication devices even in things that have not previously performed wireless communication, such as automobiles. For this reason, it is conceivable that a communication device such as a liquid crystal antenna could be attached to the roof of a car 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 the quality, strength, and other characteristics of high-frequency signals.In addition, when used as a perforated substrate with holes drilled in it, 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] In addition, while antenna applications are intended for outdoor use, communication devices have mainly been used indoors or in protected spaces. However, when mounted on automobiles, ships, etc. as liquid crystal antennas, these devices are used in harsh environments with large temperature changes, and liquid crystal 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 cooled rapidly by rain. In contrast, conventional glass substrates used in electronic devices are prone to cracking due to 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 capable of reducing the dielectric loss of high-frequency signals and having excellent thermal shock resistance, and a liquid crystal antenna and a high-frequency device using the same. [Means for solving the problem]

[0011] As a result of intensive research 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 represented 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 it suitable for use in substrates used in environments with large temperature changes, such as liquid crystal antennas, and substrates for high-frequency circuits in which holes are drilled 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 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] A liquid crystal antenna or a high-frequency device according to an aspect of the present invention has the above-mentioned glass substrate. Effect of the Invention

[0015] The glass substrate according to the present invention can reduce the dielectric loss of high-frequency signals. Furthermore, since it has excellent thermal shock resistance, it is suitable as a substrate used in an environment with large temperature changes, or a substrate for which holes are drilled using a laser or the like. Therefore, it is possible to provide a high-performance and practical liquid crystal antenna or high-frequency device. [Brief description 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 PREFERRED EMBODIMENTS

[0017] The present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be modified as desired without departing from the gist of the present invention. In addition, the symbol "to" indicating a numerical range is used to mean that the numerical values ​​before and after it are included as the lower and upper limits.

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

[0019] <Glass substrate> The glass substrate according to the present invention (hereinafter may be simply referred to as the substrate) is characterized in that it 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.

[0020] By setting the value represented 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 thermal expansion difference, 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, in order to suppress the amount of bending of the substrate during the manufacturing process (wafer process) of the high-frequency device and thereby suppress the occurrence of manufacturing defects, the Young's modulus is preferably 40 GPa or more, more preferably 50 GPa or more, and even more preferably 55 GPa or more.

[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 thermal contraction caused by a certain temperature difference between two points in the glass. The smaller the thermal expansion coefficient, the smaller the distortion caused by the same temperature difference, and the higher the thermal shock resistance. Therefore, the smaller the average thermal expansion coefficient at 50 to 350°C, the more 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. In addition, by reducing the average thermal expansion coefficient, the difference in thermal expansion coefficient with other members 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 in order to obtain thermal properties suitable for molding, it is preferably 1.0 ppm / ° C. or more, and more preferably 2.0 ppm / ° C. or more.

[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 serving 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 dielectric constant 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. The lower limit of the relative dielectric constant is not particularly limited, but 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. The lower limit of the dielectric loss tangent is not particularly limited, but is usually 0.0005 or more.

[0030] In addition, 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. The lower limit of the relative dielectric constant is not particularly limited, but 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. The lower limit of the dielectric loss tangent is not particularly limited, but is usually 0.0005 or more.

[0031] In addition, by making the values ​​of the dielectric constant and the electrostatic dissipation factor at 20°C and 35 GHz close to those at 20°C and 10 GHz, respectively, and reducing the frequency dependency (dielectric dispersion), the frequency characteristics of the dielectric properties are less likely to change, and even when the frequency during use is different, only small design changes are required, which is preferable.

[0032] The relative dielectric constant and the dielectric loss tangent can be adjusted by the composition of the glass that serves as the substrate. The dielectric constant and dielectric 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 less the stress concentration and the better the thermal shock resistance. The surface roughness of the edge of the substrate 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, as the arithmetic mean roughness Ra. The edge of the glass substrate is 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, a polishing process or a processing method such as etching using a chemical solution such as hydrofluoric acid can 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, a polishing slurry containing an abrasive, an acidic liquid or an alkaline liquid as a dispersion medium, and a polishing pad, 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 material for the glass substrate, and, for example, preliminary polishing and finish polishing may be applied in combination.

[0037] In addition, since the substrate is susceptible to breakage, cracks, chipping, etc. originating from the edge, it is preferable to chamfer at least a part of the edge in order to improve the strength of the substrate, and it is more preferable to chamfer the edge at an obtuse angle, since this further improves the strength. Examples of the chamfering form include C-chamfering, R-chamfering, and light chamfering, and the chamfering may be a complex shape that is a combination of these. Of these, C-chamfering and R-chamfering are preferable.

[0038] C-chamfering is a chamfering method in which the corners between the main surface and the edge surface are beveled off, and it is more preferable that the angle between the plane perpendicular to the main surface of the substrate and the surface after the corners have been beveled off is 120° or greater, even 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. The "arithmetic mean roughness Ra" refers to a value measured by a method conforming to JIS B0601:2001 under the conditions of an evaluation length of 8 mm, a cutoff value λc=0.8 mm, and a cutoff ratio λc / λs=100. This makes it difficult for cracks to occur starting from the chamfered surface. One method for making the arithmetic mean roughness Ra of the chamfered surface 0.2 μm or less is to polish the chamfered surface with a diamond film of #1000 to #3000.

[0041] The main surface of the 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 arithmetic mean roughness Ra value, because this can reduce the skin resistance of the wiring layer in which 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 a polishing treatment, etc., if necessary. The polishing treatment can be performed in the same manner as in the polishing treatment of the end faces.

[0043] The shape of the substrate is not particularly limited, but the area of ​​one main surface is preferably 100 cm 2 It is preferable that the distance is 225 cm 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 of the substrate is less than 10,000 cm from the viewpoint of ease of handling. 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 increasing 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 thinning and miniaturization of high-frequency devices and liquid crystal antennas using high-frequency circuits, improving production efficiency, etc., 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 curing 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 shock, more preferably 450 or more, and even more preferably 500 or more. Also, 550 or less is preferable.

[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 prevent the substrate from cracking due to mechanical shock.

[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 using a Vickers hardness tester to measure the load at which the crack initiation rate exceeds 50%.

[0050] The density of the substrate is set to 2.5 g / cm in order to reduce the weight of devices and antennas having the substrate and to reduce the brittleness of the glass, making it less likely to break 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 part of the surface in order to prevent 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 adopted. 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 during the manufacture of 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 exposure of open pores 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, since this allows the use of ultraviolet-curable materials in the lamination process and the like in the manufacturing process of high-frequency devices, antennas, etc., and improves manufacturability. Furthermore, in order to shorten the irradiation time of ultraviolet rays to the ultraviolet-curable materials in the manufacturing process of devices, antennas, etc., and to reduce uneven curing of the ultraviolet-curable materials in the thickness direction, the transmittance is more preferably 70% or more.

[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. Also, 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 an ultraviolet ray shielding ability and 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 light transmittance of the substrate at each wavelength 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 moisture content of the glass. It is determined by measuring the absorbance of the glass substrate for light with a wavelength of 2.75 to 2.95 μm, and calculating the maximum value β max This value is calculated by dividing by the thickness of the board (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 more preferable. -1 Less than 0.4 mm is more preferable. -1 Even more preferred is the following:

[0061] On the other hand, the β-OH value is 0.05 mm-1 By setting the value at or above this level, it is not necessary to melt 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 less. When the devitrification temperature is 1400° C. or less, the temperature of the components of the forming equipment can be lowered when forming the glass, and the life of the components can be extended. The devitrification temperature is more preferably 1350° C. or less, further preferably 1330° C. or less, and particularly preferably 1300° C. or less.

[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 no crystals 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.The sample after heat treatment is observed under an optical microscope.

[0065] The glass in the substrate is amorphous and indicates a solid that exhibits glass transition. It does not include crystallized glass, which is a mixture of glass and crystals, or glass sintered bodies containing crystalline fillers. The crystallinity of glass can be confirmed to be amorphous by, for example, performing X-ray diffraction measurement and finding that no clear diffraction peaks are observed.

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

[0067] The glass composition of the substrate will be described below. In this specification, "substantially free" means that it is not contained except for inevitable impurities mixed from raw materials, that is, it is not intentionally contained, and is about 0.1 mol% or less, but is not limited thereto.

[0068] Glass is SiO 2 In this specification, the term "mainly composed" means that the ratio of the component in mole percent based on oxide is SiO 2 The maximum content of SiO 2 is a network former, 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, from the viewpoint of improving the glass-forming ability and weather resistance and suppressing devitrification. On the other hand, 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, from the viewpoint of improving the melting property of the glass.

[0069] Al 2 O 3 and B. 2 O 3 The total content of (Al 2 O 3 The content of Al (including the case where the 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, since it can improve the melting property of the glass, etc. Furthermore, Al is preferably 0% or more, since it can improve the low dielectric loss of the substrate while maintaining the melting property of the glass, etc. 2 O 3 and B. 2 O 3 The total content is preferably 40% or less, more preferably 37% or less, even more preferably 35% or less, and even more preferably 33% or less.

[0070] Also, {Al 2 O 3 / (Al 2 O 3 +B 2 O 3The molar ratio of the content represented by {Al )} is preferably 0.45 or less, more preferably 0.4 or less, and even more preferably 0.3 or less, because this can enhance the low dielectric loss of the glass substrate. 2 O 3 / (Al 2 O 3 +B 2 O 3 )} is preferably 0 or more (including 0), more preferably 0.01 or more, and even more preferably 0.05 or more.

[0071] Al 2 O 3 The content of Al 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 glass, etc. In addition, Al is a component that is effective in improving weather resistance, suppressing phase separation of glass, and reducing the thermal expansion coefficient, etc. 2 O 3 may not be contained, but if contained, the content is preferably 0.5% or more.

[0072] B 2 O 3 The content of 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, since it can improve the acid resistance and the strain point. Also, since it is a component that is effective in improving the melt reactivity and lowering the devitrification temperature, etc., 2 O 3 The content 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 such 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 enhance the low dielectric loss of the glass substrate. In addition, 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 melting properties of glass.

[0074] MgO is not an essential component, but 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 reduced, and the fracture toughness value can be improved to increase 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 sufficiently obtained, and the thermal expansion coefficient can be prevented from becoming too low, so that 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 terms of suppressing the rise in the devitrification temperature, the content of MgO is preferably 13% or less, more preferably 11% or less, and even more preferably 9% or less.

[0075] CaO is a component that increases the specific elastic modulus next to MgO among alkaline earth metals and does not excessively lower the strain point, and improves solubility like MgO. Furthermore, it is a component that is less likely to increase the devitrification temperature than MgO. Although CaO is not an essential component, the effect of including CaO can be fully obtained, so its content is preferably 0.1% or more, more preferably 1% or more, and even more preferably 3% or more. In addition, the average thermal expansion coefficient does not become too high, and the increase in the devitrification temperature can be suppressed to prevent devitrification during glass production, so that the CaO content is preferably 13% or less, more preferably 10% or less, and even more preferably 8% or less.

[0076] SrO is a component that does not increase the devitrification temperature of glass and improves the melting point. Although SrO is not an essential component, the effect of including SrO can be sufficiently obtained, so that the 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. In addition, since the specific gravity is not too high and the average thermal expansion coefficient is prevented from becoming too high, the content of SrO is preferably 13% or less, more preferably 10% or less, even more preferably 7% or less, and particularly preferably 5% or less.

[0077] BaO is not an essential component, but it is a component that does not increase the devitrification temperature of glass and improves the solubility. However, if BaO is contained in a large amount, the specific gravity increases, the Young's modulus decreases, the relative dielectric constant increases, and the average thermal expansion coefficient tends to become too large. Therefore, the content of BaO is preferably 10% or less, more preferably 8% or less, even more preferably 5% or less, even more preferably 3% or less, and it is particularly preferable that BaO is not substantially contained.

[0078] It is preferable that the value represented by the following formula 1 using the contents of the above-mentioned components of the glass is 300 or less because even if distortion occurs due to a difference in thermal expansion, the stress applied to the substrate is small and the thermal shock resistance is improved, more preferably 280 or less, even more preferably 250 or less, even more preferably 220 or less, and particularly preferably 200 or less. In addition, the lower limit is not particularly limited, but from the viewpoint of obtaining thermal properties suitable for molding, 100 or more is preferable.

[0079] (1.02×SiO 2 +3.42×Al 2 O 3 +0.74×B 2 O 3 +9.17×MgO+12.55×CaO+13.85×SrO+14.44×BaO+31.61×Na 2 O+20.35×K 2 O)...Equation 1

[0080] Alkali metal oxides include Li2 O, Na 2 OK 2 O, Rb 2 O, Cs 2 O. 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 enhancing the low dielectric loss of the glass substrate. In addition, 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 total 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, Na 2 O and K 2 O is important, and Na 2 O and K 2 The total O content is preferably in the range of 0.001 to 5%.

[0082] Also, Na 2 O and K 2 The coexistence of O is preferable because it suppresses the movement of the alkaline components and can improve the low dielectric loss of the glass substrate. 2 O / (Na 2 O+K 2 O)} 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. 2 O / (Na 2 O+K 2 The molar ratio of the content represented by {R(O)} is more preferably 0.02 or more, further preferably 0.05 or more, and even more preferably 0.1 or more.

[0083] In addition to the above components, optional components include, for example, Fe. 2 O 3 , TiO 2, ZrO 2 , ZnO, Ta 2 O 5 , WO 3 , Y 2 O 3 , La 2 O 3 Among them, Fe 2 O 3 is a component that controls the light absorption performance of the glass substrate, such as infrared absorption performance and ultraviolet absorption performance, and Fe 2 O 3 The Fe content can be up to 0.012% or less in terms of the converted Fe content. If the Fe content is 0.012% or less, the low dielectric loss and UV transmittance of the glass substrate can be maintained. When Fe is contained, the content is more preferably 0.01% or less, and even more preferably 0.005% or less, in order to improve the UV transmittance. By increasing the UV transmittance of the glass substrate, UV-curable materials can be used in the lamination process and the like in the manufacturing process of high-frequency devices, antennas, and the like, and the manufacturability of high-frequency devices, antennas, and the like can be improved.

[0084] On the other hand, the glass substrate can be coated with Fe as required. 2 O 3 It is also preferable to have an Fe content of 0.05% or more in terms of increasing 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 increasing the ultraviolet shielding ability of the glass substrate, when a resin that deteriorates due to ultraviolet rays is used as a member, the glass substrate can be given a function as a protective material.

[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 shape to obtain a glass ribbon, and a slow cooling step of slowly cooling the glass ribbon to room temperature. Alternatively, the molten glass may be formed into a block shape, slowly cooled, and then cut and polished to produce a glass substrate.

[0086] In the melting step, raw materials are prepared so as to have a target composition for 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] The raw materials may also include oxides, carbonates, nitrates, hydroxides, chlorides, and other halides. When 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 mixed into the resulting glass substrate as foreign matter. 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 raw material particle size can be appropriately selected from raw materials with a large particle size of several hundred μm that does not leave any residue in the solution, to raw materials with a small particle size of about several μm that does not scatter during raw material transportation and does not aggregate as secondary particles. Granules can also be used.

[0089] The moisture content of the raw material can be adjusted appropriately to prevent the raw material from scattering. 2+ / (Fe 2+ +Fe 3+ )) and other dissolution conditions can also be adjusted appropriately.

[0090] The fining step is a step of removing bubbles from the molten glass obtained in the melting step. As the fining step, a degassing method under reduced pressure may be applied, or the degassing may be performed at a temperature higher than the melting temperature of the raw material. In the manufacturing process of the glass substrate in the embodiment, SO 2 is used as a fining agent. 3 or SnO 2 can be used. SO 3 The source is preferably a sulfate 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 sulfate, and particularly preferably CaSO 4 2H 2 O, SrSO4 and BaSO 4 However, it has a remarkable effect of enlarging bubbles and is particularly preferred.

[0091] As a clarifying agent in the degassing method under reduced pressure, it is preferable to use a halogen such as Cl or F.

[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, more preferably an alkaline earth metal chloride, and particularly preferably SrCl 2 6H 2 O, and BaCl 2 2H 2 O is particularly preferred because it has a significant effect of increasing bubble size and has low 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 particularly preferably CaF 2 has a remarkable effect of increasing the melting property of the glass raw material and is therefore more preferable.

[0094] SnO 2 Tin compounds such as 2 In molten glass, SnO 2 is reduced to SnO, and O 2 It has the effect of generating gas and growing bubbles larger. In the production of the glass substrate of the embodiment, the glass raw material is heated to about 1450 to 1750° C. and melted, so that bubbles in the molten glass become larger more effectively.

[0095] SnO 2 When using as a fining agent, the tin compound in the raw material is SnO 2 The amount is adjusted so that it contains 0.01% or more of SnO. 2The content of SnO is preferably 0.01% or more because it has a clarifying effect when the glass raw material is melted, more preferably 0.05% or more, and further preferably 0.10% or more. 2 The content of tin compounds in the alkali-free glass is preferably 0.3% or less, since this suppresses the occurrence of coloration and devitrification of the glass. The content of tin compounds in the alkali-free glass is 0.05 to 0.05% by weight of the total amount of the matrix composition. 2 In terms of conversion, 0.25% or less is more preferable, 0.2% or less is even more preferable, and 0.15% or less is particularly preferable.

[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 shape to obtain a glass ribbon. As the forming step, a known method for forming glass into a sheet shape can be applied, such as a float method in which molten glass is made to flow onto a molten metal such as tin to form a sheet shape 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 from a slit.

[0097] The annealing process is a process of cooling the glass ribbon obtained in the forming process 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 further annealed to room temperature under predetermined conditions. After cutting the annealed glass ribbon, a glass substrate is obtained.

[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 glass after cooling. In addition, the equivalent cooling rate, which is a parameter that reflects the fictive temperature, becomes too high, and as a result, low dielectric loss characteristics cannot be obtained. 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 small, the time required for the process becomes too long, resulting in low productivity. Therefore, it is preferable to set it to 0.1°C / min or more, more preferably 0.5°C / min or more, and even more preferably 1°C / min or more.

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

[0101] Glass of the target composition to be processed into a rectangular parallelepiped of 10 mm x 10 mm x 0.3 to 2.0 mm is held at strain point +170°C for 5 minutes in an infrared heating electric furnace, and then the glass is cooled to room temperature (25°C). At this time, multiple glass samples are produced by varying the cooling rate in the range of 1°C / min to 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 measurement can be done using the V-block method or the minimum deviation method. d is plotted against the logarithm of the cooling rate to obtain n d Obtain a calibration curve.

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

[0104] Although the manufacturing method of the glass substrate has been described above, the manufacturing method is not limited to the above embodiment, and the present invention includes modifications and improvements within the scope of achieving the object of 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] In addition, when manufacturing the glass substrate of the present invention, 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 platinum crucible) may be used as the melting tank or fining 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 hour to 3 hours to obtain molten glass.

[0106] In the forming step in the manufacturing process of a glass plate using a platinum crucible, the molten glass is poured onto, for example, a carbon plate or into a mold to form a plate or block. In the slow cooling step, the glass is typically held at a temperature of about Tg+50°C with respect to the glass transition point Tg, and then cooled at about 1 to 10°C / min to the vicinity of the strain point, and then cooled to room temperature at a cooling rate at which no distortion remains. After cutting into a predetermined shape and polishing, a glass substrate is obtained. In addition, the glass substrate obtained by cutting may be heated to, for example, about Tg+50°C, and then slowly cooled to room temperature at a predetermined cooling rate. In this way, the equivalent cooling temperature of the glass can be adjusted.

[0107] <High frequency circuits, liquid crystal 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 substrates for antenna components such as liquid crystal antennas. In particular, the glass substrate of the present invention is suitable for substrates for high-frequency circuits used in high-frequency devices and liquid crystal antennas because it can reduce the dielectric loss of high-frequency signals and has excellent thermal shock resistance.

[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 does it improve the characteristics such as the quality and strength of the high frequency signal mentioned above, but it also has high resistance to the thermal shock that occurs 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 layer may be formed on only one of the main surfaces of the glass substrate 2.

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

[0112] The conductor forming the first and second wiring layers 3, 4 is not particularly limited, and may be, for example, metals such as copper, gold, silver, aluminum, titanium, chromium, molybdenum, tungsten, platinum, nickel, etc., or 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 of forming the first and second wiring layers 3, 4 is not particularly limited, and various known forming methods such as a printing method using a conductive paste, a dipping method, a plating method, a vapor deposition method, and a sputtering method can be applied.

[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, the transmission loss at a frequency of, for example, 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 further high-frequency signals of 35 GHz or more, are maintained, so that a glass substrate and a circuit substrate 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] Furthermore, high frequency circuit boards include boards known as universal boards and perforated boards, in which, for example, through holes and copper foil lands are formed in a regular pattern (such as a grid) in an insulating base plate, and copper foil wiring connecting several of the lands is formed by etching. A laser or the like is used to form the through holes and perform the etching, and examples of the laser include an excimer laser, an infrared laser, and a CO 2 Laser, UV laser, etc.

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

[0117] A liquid crystal 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 liquid crystal 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. EXAMPLES

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

[0120] [Examples 1-26] Glass substrates having 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 produced by a melting method using a platinum crucible. Raw materials such as silica sand were mixed so that the glass weight was 1 kg, and a batch was prepared. The raw materials of the target composition were 100%, and sulfate was added at 0.5 to 1.0 kg, expressed as mass percentage based on oxides, and the mass percentage was calculated by adding 0.5 to 1.0 kg of sulfate. 3 The raw materials were added in an amount of 0.1% to 1%, 0.16% F, and 1% Cl. The raw materials were placed in a platinum crucible and melted by heating in an electric furnace at a temperature of 1650° C. for 3 hours to obtain molten glass.

[0121] For melting, a platinum stirrer was inserted into a platinum crucible and the glass was stirred for 1 hour to homogenize the glass. The molten glass was poured onto a carbon plate and formed into a plate. The plate-shaped glass was then placed in an electric furnace at a temperature of about Tg+50°C and held there for 1 hour. The electric furnace was then cooled to Tg-100°C at a cooling 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 end faces were 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 ends of the glass plate. The rotating grindstone may be either resin bonded or metal bonded. The abrasive grains used in the grindstone include diamond, cubic boron nitride (CBN), alumina (Al 2 O 3 ), silicon carbide (SiC), pumice, garnet, or any combination thereof.

[0123] In addition, in Tables 1 to 4, the total amount of RO *1 represents the total content of alkaline earth metal oxides (MgO+CaO+SrO+BaO), and R 2 O total amount *2 is the sum of the oxides of alkali metals (Na 2 O+K 2 O) content.

[0124] For the obtained glass substrate, the following were measured: 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 dissipation factor (20°C) at 10 GHz and 35 GHz, Vickers hardness, crack initiation load, density, specific elastic modulus, porosity, light transmittance at a wavelength of 350 nm (converted into a thickness of 0.3 to 0.4 mm), β-OH value, and devitrification temperature.

[0125] Formula 1 is expressed as the mole percentage of oxides, expressed as {1.02×SiO 2 +3.42×Al 2 O 3 +0.74×B 2 O 3 +9.17×MgO+12.55×CaO+13.85×SrO+14.44×BaO+31.61×Na 2 O+20.35×K 2 O}.

[0126] Equation 2 is a value expressed by {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 the other results are shown in Tables 5 to 8. In the tables, the values ​​in parentheses were obtained by calculation, and blanks or - mean that the values ​​were not measured.

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

[0129] (Young's Modulus) Glass having a thickness of 0.5 to 10 mm was measured by the ultrasonic pulse method according to the method specified in JIS Z 2280. The unit is 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] (Dielectric constant, dielectric 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 generation 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 cracks form 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 lump weighing approximately 20 g and containing no bubbles was measured by the Archimedes method and expressed in g / cm 3 It is expressed as:

[0135] (Porosity) The bubbles contained in the glass substrate were observed under an optical microscope, 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 given 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 is expressed as:

[0138] (Specific elastic modulus) The specific elastic modulus is calculated using the measured density and Young's modulus, and is expressed in GPa cm. 3 / 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 no crystals precipitated.

[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 represented by Equation 2) of 300 or less, and therefore is less susceptible to tensile stress even when a sudden temperature change occurs. As a result, when used in an environment where a sudden temperature change occurs, damage can be suppressed during processing steps where temperature differences 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 enabling reduction in 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 generating load is large, defects such as microcracks are unlikely to occur, so that a high-strength substrate can be obtained.

[0151] Although the present invention has been described in detail with reference to specific embodiments, it is 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, and is incorporated by reference in its entirety. In addition, 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, etc. [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 relative dielectric constant at 20°C and 35 GHz is 10 or less, and A glass substrate having a dielectric loss tangent of 0.006 or less at 20°C and 35 GHz, In mole percentage based on oxides, SiO 2 :62.0-75%, B 2 O 3: 0-23%, CaO: 0 to 5.0%, and A glass substrate satisfying the following: SrO: 0 to 3.0%.

2. A glass substrate as described in claim 1, having a Young's modulus of 70 GPa or less.

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. A glass substrate according to any one of claims 1 to 3, having a relative dielectric constant of 10 or less at 20°C and 10 GHz and a dielectric dissipation factor of 0.006 or less at 20°C and 10 GHz.

5. A glass substrate according to any one of claims 1 to 4, having a Vickers hardness of 400 to 550.

6. A glass substrate described in any one of claims 1 to 5, wherein the crack initiation load is greater than 1.96 N.

7. The glass substrate according to claim 1, having a density of 2.5 g / cm 3 or less.

8. A glass substrate according to claim 1, having a porosity of 0.1% or less.

9. A glass substrate according to claim 1, having a transmittance of 50% or more for light with a wavelength of 350 nm.

10. The glass substrate according to claim 1, wherein the β-OH value is 0.05 to 0.8 mm −1 .

11. Indicated as mole percentage on an oxide basis, containing 1 to 40% of Al 2 O 3 and B 2 O 3 in total; The molar ratio of the content represented by {Al 2 O 3 / (Al 2 O 3 +B 2 O 3 )} is 0 to 0.45, 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. The glass substrate according to claim 1, which contains 0.001 to 5% in total of alkali metal oxides, expressed in mole percentage based on oxides.

13. The glass substrate according to claim 12, wherein the molar ratio of the content of the alkali metal oxides expressed as {Na 2 O / (Na 2 O+K 2 O)} is 0.01 to 0.

99.

14. The content expressed as mole percentage based on oxides is 14. The glass substrate according to claim 1, which satisfies the relationship: (1.02×SiO 2 + 3.42×Al 2 O 3 + 0.74×B 2 O 3 + 9.17×MgO + 12.55×CaO + 13.85×SrO + 14.44×BaO + 31.61×Na 2 O + 20.35×K 2 O)≦300.

15. The glass substrate according to claim 1, containing, in mole percentages based on oxides, 0 to 10% of Al 2 O 3 and 9 to 23% of B 2 O 3 .

16. The glass substrate according to claim 1, containing 0 to 0.012% Fe calculated as Fe 2 O 3 in terms of mole percentage on an oxide basis.

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