阅读说明：本技术 基板、液晶天线和高频装置 (Substrate, liquid crystal antenna, and high-frequency device ) 是由 野村周平 小野和孝 于 2019-03-13 设计创作，主要内容包括：本发明提供一种能够降低高频信号的介电损耗且能够在宽温度区域稳定地使用的基板。本发明涉及一种基板,20℃、10GHz下的介电损耗角正切(A)为0.1以下,20℃、35GHz下的介电损耗角正切(B)为0.1以下,并且由{-40～150℃的任意温度、10GHz下的介电损耗角正切(C)/所述介电损耗角正切(A)}表示的比为0.90～1.10。另外,本发明涉及一种基板,20℃、10GHz下的相对介电常数(a)为4～10,20℃、35GHz下的相对介电常数(b)为4～10,并且由{-40～150℃的任意温度、10GHz下的相对介电常数(c)/所述相对介电常数(a)}表示的比为0.993～1.007。(The invention provides a substrate which can reduce dielectric loss of high-frequency signals and can be stably used in a wide temperature region. The present invention relates to a substrate, wherein the dielectric loss tangent (A) at 20 ℃ and 10GHz is 0.1 or less, the dielectric loss tangent (B) at 20 ℃ and 35GHz is 0.1 or less, and the ratio of the dielectric loss tangent (C) at 10GHz to the dielectric loss tangent (A) } at any temperature of-40 to 150 ℃ is 0.90 to 1.10. The present invention also relates to a substrate having a relative dielectric constant (a) of 4 to 10 at 20 ℃ and 10GHz, a relative dielectric constant (b) of 4 to 10 at 20 ℃ and 35GHz, and a ratio of (c)/the relative dielectric constant (a) } at any temperature of-40 to 150 ℃ and 10GHz, which is 0.993 to 1.007.)

1. A substrate having a dielectric loss tangent (A) of 0.1 or less at 20 ℃ and 10GHz,

a dielectric loss tangent (B) at 20 ℃ and 35GHz of 0.1 or less, and

a ratio represented by { -40 to 150 ℃ and a dielectric loss tangent (C)/the dielectric loss tangent (A) } at 10GHz is 0.90 to 1.10.

2. A substrate having a relative dielectric constant (a) of 4 to 10 at 20 ℃ and 10GHz,

a relative dielectric constant (b) at 20 ℃ and 35GHz of 4 to 10

A ratio of (c)/the relative dielectric constant (a) at 10GHz at any temperature of-40 to 150 ℃ of 0.993 to 1.007.

3. The substrate according to claim 1 or 2, wherein the longest portion of at least one main surface is 10cm or more and the shortest portion is 5cm or more.

4. The substrate according to any one of claims 1 to 3, wherein the thickness is 0.05 to 2 mm.

5. The substrate according to any one of claims 1 to 4, wherein the average coefficient of thermal expansion at 50 to 350 ℃ is 3 to 15ppm/° C.

6. The substrate according to any one of claims 1 to 5, wherein the Young's modulus is 40GPa or more.

7. The substrate according to any one of claims 1 to 6, wherein the Young's modulus is 70GPa or less.

8. The substrate according to any one of claims 1 to 7, wherein the porosity is 0.1% or less.

9. The substrate according to any one of claims 1 to 8, wherein a transmittance of light having a wavelength of 350nm is 50% or more.

10. The substrate according to any one of claims 1 to 9, which is composed of an oxide glass.

11. The substrate according to claim 10, wherein the beta-OH value is 0.05 to 0.8mm^-1。

12. The substrate of claim 10 or 11, wherein the material is selected from the group consisting of SiO₂Is used as a main component and is characterized in that,

expressed in mole percent on an oxide basis,

contains 1 to 40% of Al in total₂O₃And B₂O₃，

From { Al₂O₃/(Al₂O₃+B₂O₃) The content is 0 to 0.45 in terms of molar ratio, and

contains 0.1 to 13% in total of an alkaline earth metal oxide.

13. The substrate according to any one of claims 10 to 12, wherein the alkali metal oxide is contained in a total amount of 0.001 to 5% in terms of mole percentage based on the oxide.

14. The substrate according to claim 13, wherein the alkali metal oxide is composed of { Na ™₂O/(Na₂O+K₂O) } is 0.01 to 0.99.

15. The substrate according to any one of claims 10 to 14, wherein 0 to 10% of Al is contained in a molar percentage based on an oxide₂O₃And 9-30% of B₂O₃。

16. The substrate according to any one of claims 10 to 15, wherein Fe is expressed in terms of mole percent on an oxide basis₂O₃Contains 0 to 0.012% Fe in terms of Fe.

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

18. A liquid crystal antenna having the substrate according to any one of claims 1 to 16.

19. A high frequency device having the substrate as set forth in any one of claims 1 to 16.

Technical Field

The present invention relates to a substrate, and a liquid crystal antenna and a high frequency device having the same.

Background

In communication devices such as mobile phones, smart phones, personal digital assistants, and Wi-Fi devices, and electronic devices such as Surface Acoustic Wave (SAW) devices, radar components, and antenna components, higher signal frequencies are being used to increase communication capacity and communication speed. As a circuit board used for such a communication device and an electronic device for high frequency use, an insulating substrate such as a resin substrate, a ceramic substrate, or a glass substrate is generally used. In order to ensure characteristics such as quality and strength of high-frequency signals, it is required to reduce transmission loss due to dielectric loss, conductor loss, and the like in an insulating substrate used in communication equipment and electronic devices for high-frequency applications.

In addition, since various devices have communication functions due to the expansion of IoT, there is a demand for mounting a communication device even in a device such as an automobile which has not performed wireless communication so far. Therefore, it is considered that a communication device such as a liquid crystal antenna is mounted on the roof of an automobile to communicate with a satellite (see patent documents 1 and 2).

Disclosure of Invention

In the case of performing high-frequency and large-capacity communication, it is preferable that the dielectric characteristics of the substrate be stable over a wide frequency band. However, in the conventional resin substrate and glass substrate, the amount of change in dielectric characteristics is large particularly when the frequency changes in the GHz band, and thus the resin substrate and glass substrate are not suitable for use as a substrate of a communication device.

In addition, for antenna applications, communication devices have heretofore been used mainly indoors. However, when the liquid crystal antenna is mounted on a device such as an automobile or a ship which is used in a wide temperature range, it is considered that the liquid crystal antenna is used in a severe environment in which a temperature change is large. On the other hand, if the glass substrate is a conventional glass substrate which has been used in electronic devices, the dielectric characteristics of the substrate change due to temperature change, which greatly affects the circuit and antenna performance.

In view of the above circumstances, an object of the present invention is to provide a substrate that can reduce dielectric loss of a high-frequency signal and can be stably used in a wide temperature range, and a liquid crystal antenna and a high-frequency device using the substrate.

As a result of intensive studies to achieve the above object, the present inventors have found that desired dielectric properties can be stably obtained regardless of the environment when signal processing is performed by reducing the frequency dependence of the dielectric loss tangent or the relative permittivity and setting the difference in the dielectric loss tangent or the relative permittivity within a certain range in a temperature range of-40 to 150 ℃. This makes it possible to apply the substrate for use in various environments such as equatorial regions and cold regions, and the substrate for high-frequency circuits.

That is, one embodiment of the substrate of the present invention is a substrate in which the dielectric loss tangent (A) at 20 ℃ and 10GHz is 0.1 or less, the dielectric loss tangent (B) at 20 ℃ and 35GHz is 0.1 or less, and the ratio of the dielectric loss tangent (C)/the dielectric loss tangent (A) } at any temperature of-40 to 150 ℃ and at 10GHz is 0.90 to 1.10.

In another embodiment of the substrate of the present invention, the relative permittivity (a) at 20 ℃ and 10GHz is 4 to 10, the relative permittivity (b) at 20 ℃ and 35GHz is 4 to 10, and the ratio of the relative permittivity (c) at 10GHz to the relative permittivity (a) } at any temperature of-40 to 150 ℃ is 0.993 to 1.007.

The substrate is used for a liquid crystal antenna or a high frequency circuit.

In addition, one embodiment of the liquid crystal antenna or the high frequency device of the present invention includes the substrate.

According to the substrate of the present invention, it is possible to prevent a change in the dielectric characteristics of the substrate due to a temperature change and stably reduce the dielectric loss of a high-frequency signal in a wide temperature range, and therefore, it is possible to provide a high-performance and practical liquid crystal antenna and high-frequency device.

Drawings

Fig. 1 is a cross-sectional view showing an example of the configuration of a high-frequency circuit.

Fig. 2 is a graph showing the temperature dependence of the dielectric loss tangent at 10GHz (fig. 2(a)) and the temperature dependence of the relative dielectric constant (fig. 2(b)) of various substrates.

Detailed Description

The present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be implemented by being arbitrarily changed within a range not departing from the gist of the present invention. "to" indicating a numerical range is used to include numerical values before and after the range as the lower limit value and the upper limit value.

When the substrate is a glass substrate made of glass, unless otherwise specified, the content of each component in the glass substrate is expressed by mole percentage based on oxides. The term "high frequency" means a frequency of 10GHz or more, preferably more than 30GHz, and more preferably 35GHz or more.

< substrate >

One embodiment (hereinafter, also abbreviated as "1 st embodiment") of the substrate of the present invention is characterized in that the dielectric loss tangent (a) at 20 ℃ and 10GHz is 0.1 or less, the dielectric loss tangent (B) at 20 ℃ and 35GHz is 0.1 or less, and the ratio represented by { -40 to 150 ℃ at any temperature and 10 GHz/the dielectric loss tangent (a) } is 0.90 to 1.10.

In another aspect of the substrate of the present invention (hereinafter, also abbreviated as "2 nd aspect"), the relative permittivity (a) at 20 ℃ and 10GHz is 4 to 10, the relative permittivity (b) at 20 ℃ and 35GHz is 4 to 10, and the ratio of the relative permittivity (c)/the relative permittivity (a) } at 10GHz is 0.993 to 1.007 at any temperature of-40 to 150 ℃.

The dielectric loss in the high frequency region can be reduced by reducing the relative dielectric constant and/or the dielectric loss tangent of the substrate.

The substrate of the invention of claim 1 has a dielectric loss tangent (tan) (A) at 20 ℃ and 10GHz of 0.1 or less, preferably 0.05 or less, more preferably 0.01 or less, still more preferably 0.005 or less, and particularly preferably 0.003 or less.

In embodiment 2 of the substrate of the present invention, the dielectric loss tangent (tan) (A) at 20 ℃ and 10GHz is preferably 0.1 or less, more preferably 0.05 or less, still more preferably 0.01 or less, yet more preferably 0.005 or less, and particularly preferably 0.003 or less.

The lower limit of the dielectric loss tangent (A) is not particularly limited, but is usually 0.0001 or more.

The substrate of the invention of claim 1 has a dielectric loss tangent (B) at 20 ℃ and 35GHz of 0.1 or less, preferably 0.05 or less, more preferably 0.01 or less, still more preferably 0.005 or less, and particularly preferably 0.003 or less.

In the 2 nd embodiment of the substrate of the present invention, the dielectric loss tangent (B) at 20 ℃ and 35GHz is preferably 0.1 or less, more preferably 0.05 or less, still more preferably 0.01 or less, yet more preferably 0.005 or less, and particularly preferably 0.003 or less.

The lower limit of the dielectric loss tangent (B) is not particularly limited, and is usually 0.0001 or more.

If the value of the dielectric loss tangent changes depending on the temperature, the signal characteristics change when the usage environment of the device changes, and a desired signal intensity cannot be obtained.

Accordingly, the substrate of the invention of the 1 st aspect is a substrate having a value obtained by cutting off the dielectric loss tangent (A) at 20 ℃ and 10GHz at any temperature of-40 to 150 ℃ and at 10GHz, that is, a ratio represented by { -40 to 150 ℃ and dielectric loss tangent (C)/dielectric loss tangent (A) } at 10GHz is 0.90 to 1.10, and is preferably as close to 1.

In the substrate of the invention of claim 2, the ratio represented by { -40 to 150 ℃ and dielectric loss tangent (C)/dielectric loss tangent (A) } at 10GHz is preferably 0.90 to 1.10, and is more preferably as close to 1.

In the case of a glass substrate, the dielectric loss tangent can be adjusted by the composition of the glass or the like. The dielectric loss tangent can be measured by a method specified in JIS R1641 (2007) using a cavity resonator and a vector network analyzer.

The ratio represented by { -dielectric loss tangent (C)/dielectric loss tangent (A) } at 10GHz at an arbitrary temperature of-40 to 150 ℃ is calculated by measuring the dielectric loss tangent at 10GHz at-40 to 150 ℃ at 10 ℃ and determining the ratio of the maximum value and the minimum value thereof to the value of the dielectric loss tangent (A) at 20 ℃ and 10 GHz.

In embodiment 1 of the substrate of the present invention, the relative dielectric constant (a) at 20 ℃ and 10GHz is preferably 10 or less, more preferably 8 or less, further preferably 6 or less, further preferably 5 or less, and particularly preferably 4.5 or less. In embodiment 1 of the substrate of the present invention, the lower limit of the relative permittivity (a) is not particularly limited, but is preferably 4 or more in view of being able to reduce the size of the device.

In the substrate of the invention of claim 2, the relative permittivity (a) at 20 ℃ and 10GHz is 10 or less, more preferably 8 or less, still more preferably 6 or less, still more preferably 5 or less, and particularly preferably 4.5 or less. In the substrate of claim 2 of the present invention, the lower limit of the relative permittivity (a) is 4 or more in view of being able to reduce the size of the device.

In embodiment 1 of the substrate of the present invention, the relative dielectric constant (b) at 20 ℃ and 35GHz is preferably 10 or less, more preferably 8 or less, further preferably 6 or less, further preferably 5 or less, and particularly preferably 4.5 or less. In embodiment 1 of the substrate of the present invention, the lower limit of the relative permittivity (b) is not particularly limited, but is preferably 4 or more in view of being able to reduce the size of the device.

In the substrate of the invention of claim 2, the relative permittivity (b) at 20 ℃ and 35GHz is 10 or less, preferably 8 or less, more preferably 6 or less, still more preferably 5 or less, and particularly preferably 4.5 or less. In the substrate of claim 2 of the present invention, the lower limit of the relative permittivity (b) is 4 or more in view of being able to reduce the size of the device.

If the value of the relative permittivity changes depending on the temperature, the signal characteristics change when the usage environment of the device changes, and a desired signal intensity cannot be obtained.

Accordingly, the substrate of the invention of the 1 st aspect is a substrate having a value obtained by dividing the relative permittivity at 10GHz by the relative permittivity (a) at 20 ℃ and 10GHz at any temperature of-40 to 150 ℃, i.e., a ratio represented by { -40 to 150 ℃ and the relative permittivity (c)/the relative permittivity (a) } at 10GHz is preferably 0.993 to 1.007, and is more preferably as close to 1.

The substrate of the invention of claim 2 has a value obtained by dividing the relative permittivity at 10GHz by the relative permittivity (a) at 20 ℃ and 10GHz at any temperature of-40 to 150 ℃, i.e., the ratio of the relative permittivity (c)/the relative permittivity (a) at 10GHz at any temperature of-40 to 150 ℃ is 0.993 to 1.007, and is preferably as close to 1 as possible.

In the case of a glass substrate, the relative dielectric constant can be adjusted by the composition of the glass or the like. The relative dielectric constant can be measured by a method specified in JIS R1641 (2007) using a cavity resonator and a vector network analyzer.

Further, the ratio represented by { -40 to 150 ℃ relative permittivity (c)/relative permittivity (a) } at 10GHz is calculated by measuring the relative permittivity at 10GHz at-40 to 150 ℃ at 10 ℃ in the same manner as the dielectric loss tangent, and obtaining the ratio of the maximum value and the minimum value thereof to the value of the relative permittivity (A) at 20 ℃ and 10 GHz.

When the substrate is used for a high-frequency circuit, the young's modulus is preferably 40GPa or more, more preferably 50GPa or more, and still more preferably 55GPa or more, from the viewpoint of suppressing the amount of deflection of the substrate during the manufacturing process (wafer process) of the high-frequency device and suppressing the occurrence of manufacturing defects.

On the other hand, from the viewpoint of reducing the generation of thermal stress due to a rapid temperature difference, the young's modulus is preferably 70GPa or less, more preferably 67GPa or less, still more preferably 64GPa or less, and still more preferably 60GPa or less.

In the case of a glass substrate, the young's modulus can be adjusted by the composition of the glass as the substrate. The young's modulus can be measured by an ultrasonic pulse method in accordance with the method defined in JIS Z2280 (1993).

When a semiconductor package or the like is formed as a high-frequency device using a substrate, the average thermal expansion coefficient at 50 to 350 ℃ is preferably 3 to 15 ppm/DEG C in view of easily and appropriately adjusting the difference in thermal expansion coefficient with other members. Thus, for example, in the case of a 2.5D or 3D (three-dimensional) mounting type glass through wiring board (TGV board) for high-frequency use, the difference in thermal expansion coefficient with other members such as a semiconductor chip can be adjusted more appropriately.

In the case of a glass substrate, the thermal expansion coefficient can be adjusted by the content of, in particular, an alkali metal oxide or an alkaline earth metal oxide in the composition of the glass. The average thermal expansion coefficient of 50 to 350 ℃ can be measured by a differential thermal expansion instrument according to the method specified in JIS R3102 (1995).

The surface roughness of at least one of the main surfaces is preferably 1.5nm or less in terms of arithmetic average roughness Ra, because the surface resistance of the substrate is reduced in a high-frequency region exceeding 30GHz, and the conductor loss can be reduced by reducing the surface resistance of the wiring layer causing the skin effect when the substrate is used in, for example, a high-frequency circuit. The arithmetic average roughness Ra of the main surface of the substrate is more preferably 1.0nm or less, and still more preferably 0.5nm or less. The surface roughness of the main surface can be achieved by subjecting the surface of the main surface to a polishing treatment or the like as necessary.

When the substrate is a glass substrate, for example, mechanical polishing using a polishing agent containing cerium oxide, colloidal silica, or the like as a main component and a polishing pad, chemical mechanical polishing using a polishing agent, a polishing slurry and a polishing pad containing an acidic liquid or an alkaline liquid as a dispersion medium, chemical polishing using an acidic liquid or an alkaline liquid as an etching liquid, or the like can be applied to the polishing treatment. These polishing treatments may be applied depending on the surface roughness of the glass plate as a raw material of the glass substrate, and for example, pre-polishing and finish-polishing may be applied in combination.

The size and shape of the substrate are not particularly limited, and for example, when a large-sized device is manufactured in a device manufacturing process, a plurality of devices are manufactured in the same substrate, or the like, it is preferable that the longest portion of at least one main surface is 10cm or more and the shortest portion is 5cm or more.

In addition, from the viewpoint of improving detection sensitivity in manufacturing of a device such as a liquid crystal antenna and the like and from the viewpoint of simplifying a mounting process in manufacturing of a high-frequency device, the area of at least one main surface is preferably 50cm²Above, more preferably 100cm²Above, more preferably 225cm²The above. Further, it is preferably 100000cm in terms of easiness of handling of the substrate²Hereinafter, more preferably 10000cm²Hereinafter, more preferably 3600cm²The following.

The thickness of the substrate is preferably 0.05mm or more, more preferably 0.1mm or more, and still more preferably more than 0.2mm, from the viewpoint of maintaining the strength of the substrate when flowing. By increasing the thickness of the substrate, the ultraviolet shielding ability can be improved, and the resin that is deteriorated by ultraviolet rays can be protected.

On the other hand, from the viewpoint of thinning and downsizing of a high-frequency device and a liquid crystal antenna using a high-frequency circuit, and improvement of production efficiency, it is preferably 2mm or less, more preferably 1.0mm or less, further preferably 0.7mm or less, and further preferably 0.5mm or less. By making the substrate thin, the ultraviolet transmittance can be improved, and the manufacturability can be improved by using an ultraviolet curing material in the manufacturing process of devices, antennas, and the like.

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 and the like when manufacturing a high-frequency device. From the viewpoint of the liquid crystal antenna, it is preferable that the wiring defect is 0.0001% or less in order to suppress the occurrence of the wiring defect due to the exposure of the open hole to the surface.

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

The transmittance of light having a wavelength of 350nm of the substrate is preferably 50% or more in view of the fact that an ultraviolet-curable material can be used in a lamination step or the like in a manufacturing step of a high-frequency device, an antenna, or the like, and the manufacturability can be improved. Further, in order to shorten the irradiation time of the ultraviolet-curable material with ultraviolet rays in the manufacturing process of the device, the antenna, and the like and to reduce the curing unevenness of the ultraviolet-curable material in the thickness direction, it is more preferably 70% or more.

For the same reason as described above, the transmittance of light having a wavelength of 300nm of the substrate is preferably 50% or more, more preferably 60% or more, and still more preferably 70% or more. The transmittance of light having a wavelength of 250nm is preferably 5% or more, more preferably 10% or more, and still more preferably 20% or more.

On the other hand, when a resin which is deteriorated by ultraviolet rays is used as a member in a device, an antenna, or the like, the transmittance of light having a wavelength of 350nm is preferably 80% or less, more preferably 60% or less, even more preferably 30% or less, and most preferably 10% or less, from the viewpoint of imparting a function as a protective material by imparting ultraviolet shielding ability to a substrate.

For the same reason as described above, the transmittance of light having a wavelength of 300nm of the substrate is preferably 80% or less, more preferably 60% or less, still more preferably 30% or less, and still more preferably 10% or less. The transmittance of light having a wavelength of 250nm is preferably 60% or less, more preferably 30% or less, still more preferably 10% or less, and still more preferably 5% or less.

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

The substrate of the present invention is not particularly limited as long as it has the above-described characteristics, and may include any of a resin substrate, a ceramic substrate, and a glass substrate. The glass substrate may be an amorphous substrate made of a nonmetallic inorganic solid exhibiting glass transition, and is more preferably made of oxide glass. The glass composition does not include crystallized glass, which is a mixture of glass and crystals, and a glass sintered body containing a crystalline filler. The crystallinity of the glass can be measured by, for example, X-ray diffraction, and it is confirmed that the glass is amorphous by no clear diffraction peak being observed.

When the substrate is a glass substrate, the beta-OH value of the glass substrate is preferably 0.05-0.8 mm^-1. The beta-OH value is used as an index of the moisture content of the glass, and is obtained by measuring the absorbance of a glass substrate with respect to light having a wavelength of 2.75 to 2.95 [ mu ] m and using the maximum value beta thereof_maxDivided by the thickness (mm) of the substrate.

By bringing the beta-OH value to 0.8mm^-1Hereinafter, the low dielectric loss property of the substrate is preferably further improved, and more preferably 0.6mm^-1Hereinafter, more preferably 0.5mm^-1The thickness is preferably 0.4mm or less^-1The following.

On the other hand, by setting the value of beta-OH to 0.05mm^-1As described above, it is preferable because glass productivity, bubble quality, and the like can be improved without requiring melting in an extreme dry environment or extremely reducing the amount of water in the raw material. The beta-OH value is more preferably 0.1mm^-1Above, more preferably 0.2mm^-1The above. The β -OH value can be adjusted by the composition of the glass in the substrate and the selection of the raw material.

The devitrification temperature of the glass substrate is preferably 1400 ℃ or lower. If the devitrification temperature is 1400 ℃ or lower, the temperature of the member of the molding equipment can be lowered at the time of molding the glass, and the life of the member can be extended. The devitrification temperature is more preferably 1350 ℃ or less, still more preferably 1330 ℃ or less, and particularly preferably 1300 ℃ or less.

The devitrification temperature of the glass is an average value of the highest temperature at which crystals are precipitated on the surface or inside of the glass and the lowest temperature at which crystals are not precipitated, which are observed by an optical microscope of a sample after heat treatment by placing the crushed glass particles in a platinum dish and heat-treating the glass particles in an electric furnace controlled to a constant temperature for 17 hours.

The details of the method for producing a substrate will be described later, and in the case of a glass substrate, the substrate is formed by melting and solidifying a glass raw material. The method for producing the substrate is not particularly limited, and for example, a method of forming a general molten glass into a predetermined thickness by a float method, gradually cooling the glass, and then cutting the glass into a desired shape to obtain a flat glass can be applied.

The composition of the glass in the glass substrate will be described below. In the present specification, "substantially not containing" means not containing, i.e., not intentionally containing, other than inevitable impurities mixed in from raw materials or the like, and is not substantially 0.1 mol% or less, but is not limited thereto.

The glass is preferably SiO₂Is the main component. In the present specification, "as a main component" means that SiO is contained in a proportion of a component of mol% based on an oxide₂The content of (c) is the largest. SiO 2₂Is a network-forming substance, and the content thereof is more preferably 40% or more, still more preferably 45% or more, still more preferably 50% or more, and particularly preferably 55% or more, from the viewpoint of being able to improve glass-forming ability, weather resistance, and being able to suppress devitrification. On the other hand, from the viewpoint of improving the melting property of the glass, it is preferably 75% or less, more preferably 74% or less, still more preferably 73% or less, and still more preferably 72% or less.

Al is considered to improve the melting property of the glass and the like₂O₃And B₂O₃(including Al) in total₂O₃The content of (b) is 0) is preferably 1% or more, more preferably 3% or more, still more preferably 5% or more, and still more preferably 7% or more. In addition, the low dielectric loss property of the substrate can be improved while maintaining the melting property of the glassAl is added₂O₃And B₂O₃The total content of (a) is preferably 40% or less, more preferably 37% or less, still more preferably 35% or less, and still more preferably 33% or less.

In addition, from the viewpoint of improving the low dielectric loss of the glass substrate, { Al }₂O₃/(Al₂O₃+B₂O₃) The content molar ratio expressed by is preferably 0.45 or less, more preferably 0.4 or less, and still more preferably 0.3 or less. In addition, from { Al₂O₃/(Al₂O₃+B₂O₃) The content molar ratio represented by (i) is preferably 0 or more (including 0), more preferably 0.01 or more, and still more preferably 0.05 or more.

Al is considered to be capable of improving the melting property of the glass and the like₂O₃The content of (b) is preferably 15% or less, more preferably 14% or less, and further preferably 10% or less. In addition, Al may not be contained from the viewpoint of components that exert effects on improvement of weather resistance, suppression of phase separation of glass, reduction of thermal expansion coefficient, and the like₂O₃However, the content in the case of inclusion is more preferably 0.5% or more.

From the viewpoint of being able to improve acid resistance and strain point, B₂O₃The content of (b) is preferably 30% or less, more preferably 28% or less, still more preferably 26% or less, still more preferably 24% or less, and particularly preferably 23% or less. In addition, B is a component which exerts an effect on the improvement of the melting reactivity, the decrease of the devitrification temperature, and the like₂O₃The content of (b) is preferably 9% or more, more preferably 13% or more, and further preferably 16% or more.

The alkaline earth metal oxide includes MgO, CaO, SrO, and BaO, and all of them function as a component for improving the melting reactivity of the glass. The total content of such alkaline earth metal oxides is preferably 13% or less, more preferably 11% or less, still more preferably 10% or less, still more preferably 8% or less, and particularly preferably 6% or less, from the viewpoint of improving the low dielectric loss property of the glass substrate. In addition, the total content of the alkaline earth metal oxides is preferably 0.1% or more, more preferably 3% or more, and still more preferably 5% or more, from the viewpoint of maintaining the melting property of the glass well.

MgO is not an essential component, but is a component capable of increasing the young's modulus without increasing the specific gravity. That is, MgO is a component capable of improving the relative elastic modulus, and the inclusion of MgO can reduce the problem of deflection, improve the fracture toughness value, and improve the glass strength. Further, MgO is a component that also improves the melting property. The content of MgO is preferably 0.1% or more, more preferably 1% or more, and even more preferably 3% or more, from the viewpoint that the effect of containing MgO is sufficiently obtained and the thermal expansion coefficient can be suppressed from becoming excessively low. On the other hand, the content of MgO is preferably 13% or less, more preferably 11% or less, and further preferably 9% or less, from the viewpoint of suppressing the increase in devitrification temperature.

CaO is a component of alkaline earth metals which has a characteristic of increasing the relative elastic modulus without excessively lowering the strain point next to MgO, and also improves the meltability as with MgO. Further, the composition is characterized in that the devitrification temperature is less likely to be increased than that of MgO. CaO is not an essential component, but the content thereof is preferably 0.1% or more, more preferably 1% or more, and further preferably 3% or more, from the viewpoint of sufficiently obtaining the effect of containing CaO. In addition, the content of CaO is preferably 13% or less, more preferably 10% or less, and further preferably 8% or less, from the viewpoint that the average thermal expansion coefficient does not become excessively high, and the devitrification can be prevented during the production of the glass by suppressing the increase in devitrification temperature.

SrO is a component that improves the meltability without increasing the devitrification temperature of the glass. SrO is not an essential component, but the content thereof is preferably 0.1% or more, more preferably 0.5% or more, further preferably 1% or more, further preferably 1.5% or more, and particularly preferably 2% or more, from the viewpoint of sufficiently obtaining the effect of containing SrO. In addition, the SrO content is preferably 13% or less, more preferably 10% or less, further preferably 7% or less, and particularly preferably 5% or less, in view of preventing the specific gravity from being excessively increased and also preventing the average thermal expansion coefficient from becoming excessively high.

BaO is not an essential component, but is a component which improves the meltability without increasing the devitrification temperature of the glass. However, if BaO is contained in a large amount, the specific gravity becomes large, the young's modulus decreases, the relative permittivity becomes high, 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, further preferably 5% or less, further preferably 3% or less, and particularly preferably substantially not contained.

Examples of the alkali metal oxide include Li₂O、Na₂O、K₂O、Rb₂O、Cs₂And O. From the viewpoint of improving the low dielectric loss of the glass substrate, the total content of such alkali metal oxides is preferably 5% or less, more preferably 3% or less, still more preferably 1% or less, still more preferably 0.2% or less, particularly preferably 0.1% or less, and most preferably 0.05% or less. In addition, from the viewpoint of obtaining a practical meltability of glass and productivity of a glass substrate without performing excessive raw material purification and adjusting the thermal expansion coefficient of the glass substrate, it is preferably 0.001% or more, more preferably 0.002% or more, further preferably 0.003% or more, and further preferably 0.005% or more.

In the above alkali metal oxide, Na₂O and K₂O is particularly important, Na₂O and K₂The total content of O is preferably in the range of 0.001 to 5%. In addition, by reacting Na₂O and K₂O coexists and the movement of the alkali component can be suppressed, so that the low dielectric loss of the glass substrate can be improved, which is preferable. I.e., from { Na₂O/(Na₂O+K₂O) } is preferably 0.01 to 0.99, more preferably 0.98 or less, still more preferably 0.95 or less, and still more preferably 0.9 or less. On the other hand, { Na }₂O/(Na₂O+K₂The molar ratio of the content represented by O) } is more preferably 0.02 or more, still more preferably 0.05 or more, and still more preferably 0.1 or more.

In addition to the above components, for example, Fe may be contained₂O₃、TiO₂、ZrO₂、ZnO、Ta₂O₅、WO₃、Y₂O₃、La₂O₃And the like as an arbitrary component. Wherein, Fe₂O₃Is a component for controlling the light absorption properties of the glass substrate, for example, infrared absorption properties and ultraviolet absorption properties, and may be Fe as required₂O₃The content of Fe is 0.012% or less in terms of Fe content. If the content of Fe 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 thereof is more preferably 0.01% or less, and still more preferably 0.005% or less, in order to improve the ultraviolet transmittance. By increasing the ultraviolet transmittance of the glass substrate, an ultraviolet-curable material can be used in a lamination step or the like in a production step of a high-frequency device, an antenna or the like, and the productivity of the high-frequency device, the antenna or the like can be improved.

On the other hand, the glass substrate is preferably made of Fe if necessary from the viewpoint of improving the ultraviolet shielding ability₂O₃The content of Fe is 0.05% or more in terms of Fe content. The content of Fe is more preferably 0.07% or more, and still more preferably 0.1% or more. By thus improving the ultraviolet shielding ability of the glass substrate, when a resin that is deteriorated by ultraviolet rays is used as a member, a function as a protective material can be provided to the glass substrate.

< method for manufacturing substrate >

(glass substrate)

The glass substrate can be obtained by a manufacturing method including the steps of: a melting step of heating a glass raw material to obtain molten glass; a fining step of removing bubbles from the molten glass; a molding step of forming 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 glass substrate may be produced by forming molten glass into a block, gradually cooling the block, and then cutting and polishing the block.

The melting step is a step of preparing a raw material so as to have a composition of a target glass substrate, and continuously charging the raw material into a melting furnace, preferably heating the raw material to about 1450 to 1750 ℃.

The raw material may be a halide such as an oxide, a carbonate, a nitrate, a hydroxide, or a chloride. In the case where the step of bringing the molten glass into contact with platinum is present in the melting or refining step, fine platinum particles may be eluted into the molten glass and mixed as foreign matter into the obtained glass substrate, but the use of the nitrate raw material has an effect of preventing the formation of platinum foreign matter.

As the nitrate, strontium nitrate, barium nitrate, magnesium nitrate, calcium nitrate, or the like can be used. More preferably, strontium nitrate is used. The particle size of the raw material may be suitably selected from a large particle size raw material of several hundreds of μm, which does not cause a residue of melting, to a small particle size raw material of several μm, which does not cause scattering during transportation of the raw material and does not aggregate into secondary particles. In addition, granules may be used.

The water content of the raw material may be appropriately adjusted to prevent scattering of the raw material. The beta-OH value and the degree of oxidation-reduction of Fe (redox [ Fe ]) can also be appropriately adjusted²⁺/(Fe²⁺+Fe³⁺)]) And melting conditions are used.

The fining step is a step of removing bubbles from the molten glass obtained in the melting step. As the clarification step, a defoaming method by a reduced pressure may be applied, or defoaming may be performed by forming a temperature higher than the melting temperature of the raw material. In the process for producing a glass substrate according to the embodiment, SO may be used₃Or SnO₂As a clarifying agent.

As SO₃A source, preferably a sulfate of at least one element selected from the group consisting of Al, Na, K, Mg, Ca, Sr and Ba, more preferably a sulfate of an alkaline earth metal, wherein CaSO₄·2H₂O、SrSO₄And BaSO₄The effect of increasing bubbles is remarkable, and is particularly preferable.

As the clarifying agent in the defoaming method by reduced pressure, a halogen such as Cl or F is preferably used.

As the Cl source, at least one element selected from the group consisting of Al, Mg, Ca, Sr and Ba is preferableChlorides, more preferably chlorides of alkaline earth metals, wherein SrCl₂·6H₂O and BaCl₂·2H₂O is particularly preferable because it has a remarkable effect of increasing bubbles and is low in deliquescence.

As the F source, a fluoride of at least one element selected from the group consisting of Al, Na, K, Mg, Ca, Sr and Ba is preferable, and a fluoride of an alkaline earth metal is more preferable, wherein CaF₂The effect of increasing the meltability of the glass raw material is remarkable, and more preferably.

In SnO₂The tin compound represented by the formula produces O in the glass melt₂A gas. In the molten glass, has a temperature of 1450 ℃ or higher from SnO₂Reduction to SnO to produce O₂Gas, the effect of growing bubbles largely. In the production of the glass substrate according to the embodiment, the glass raw material is heated to about 1450 to 1750 ℃ and melted, and therefore bubbles in the glass melt become larger more effectively.

Using SnO₂When used as a fining agent, the tin compound in the raw material is SnO in an amount of 100% relative to the total amount of the above-mentioned mother composition₂Is prepared in a manner of containing more than 0.01 percent in terms of conversion. By reacting SnO₂The content is preferably 0.01% or more because a refining action at the time of melting of the glass raw material can be obtained, and more preferably 0.05% or more, and still more preferably 0.10% or more. On the other hand, by reacting SnO₂The content of 0.3% or less is preferable because the occurrence of coloring and devitrification of the glass can be suppressed. SnO represents the content of tin compound in the alkali-free glass relative to 100% of the total amount of the above mother compositions₂The conversion is more preferably 0.25% or less, still more preferably 0.2% or less, and particularly preferably 0.15% or less.

The forming step is a step of forming the molten glass from which the bubbles have been removed in the fining step into a sheet shape to obtain a glass ribbon. As the forming step, a known method of forming glass into a plate shape, such as a float method of forming a glass ribbon by flowing molten glass onto a molten metal such as tin into a plate shape, an overflow down-draw method (melting method) of flowing molten glass from a trough-like member downward, a slot down-draw method from a slot, or the like, can be applied.

The slow cooling step is a step of cooling the glass ribbon obtained in the molding step to a room temperature state under controlled cooling conditions. In the annealing step, the glass ribbon is cooled so that a predetermined average cooling rate becomes R (c/min) in a temperature range between an annealing point and a strain point of the formed glass, and is annealed to a room temperature state under predetermined conditions. The glass ribbon after the slow cooling was cut to obtain a glass substrate.

If the cooling rate R in the slow cooling step is too high, strain tends to remain in the cooled glass. In addition, the equivalent cooling rate, which is a parameter reflecting the virtual temperature, becomes too high, and as a result, the low dielectric loss characteristics cannot be obtained. Therefore, it is preferable to set R so that the equivalent cooling rate becomes 800 ℃/min or less. The equivalent cooling rate is more preferably 400 ℃/min or less, still more preferably 100 ℃/min or less, and particularly preferably 50 ℃/min or less. On the other hand, if the cooling rate is too low, the time required for the process becomes too long, and the productivity becomes low. Therefore, the equivalent cooling rate is preferably set to 0.1 ℃/min or more, more preferably 0.5 ℃/min or more, and still more preferably 1 ℃/min or more.

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

A glass having a composition to be processed into a rectangular parallelepiped of 10mm x 0.3 to 2.0mm is held at a strain point of +170 ℃ for 5 minutes by using an infrared heating electric furnace, and then the glass is cooled to room temperature (25 ℃). At this time, a plurality of glass samples were produced in which the cooling rate was varied from 1 ℃/min to 1000 ℃/min.

The refractive index n of the d-line (wavelength 587.6nm) of a plurality of glass samples was measured using a precision refractive index measuring apparatus (for example, KPR2000 manufactured by Shimadzu corporation)_d. The measurement may be carried out by a V-block method or a minimum deflection angle method. By converting the obtained n_dPlotting the logarithm of the cooling rate to obtain n_dCalibration curve against the cooling rate described above.

Then, the measurement is carried out by the above-mentioned measuring method, and the product is obtained by actually carrying out the steps of melting, molding, cooling, etcN of glass of the same composition_d. N obtained by summing the above-mentioned calibration curves_dThe corresponding cooling rate (referred to as an equivalent cooling rate in the present embodiment).

In addition, in the method for producing a glass substrate, it is preferable that any part of the transport pipe for molten glass during production is sufficiently stirred and the temperature distribution is reduced at the time of slow cooling after sheet molding, since the in-plane variation range of the dielectric loss tangent and the relative permittivity at 20 ℃ and 10GHz can be further reduced.

Although the method for producing a glass substrate has been described above, the method for producing a glass substrate is not limited to the above embodiment, and variations, improvements, and the like within a range in which the object of the present invention can be achieved are included in the present invention. For example, in the case of producing the glass substrate of the present invention, the glass may be formed into a plate shape by a press molding method in which molten glass is directly molded into a plate shape.

In addition, in the production of the glass substrate of the present invention, in addition to the production method using a refractory melting vessel, a crucible made of platinum or an alloy containing platinum as a main component (hereinafter referred to as a platinum crucible) may be used for the melting vessel or the clarifying vessel. When a platinum crucible is used, the melting step prepares a raw material so as to have a composition of the obtained glass substrate, and the platinum crucible containing the raw material is heated, preferably to around 1450 to 1700 ℃. The molten glass was stirred for 1 to 3 hours with a platinum stirrer.

In the molding step of the glass plate production step using a platinum crucible, molten glass is poured onto, for example, a carbon plate or a mold frame to form a plate or a block. The slow cooling step is typically performed by maintaining the glass transition point Tg at a temperature of about Tg +50 ℃, then cooling the glass to a temperature near the strain point at about 1 to 10 ℃/min, and then cooling the glass to room temperature at a cooling rate such that no strain remains. After cutting and grinding into a predetermined shape, a glass substrate was obtained. The glass substrate obtained by cutting may be heated to approximately Tg +50 ℃, for example, and then gradually cooled to room temperature at a predetermined cooling rate. By doing so, the equivalent cooling temperature of the glass can be adjusted.

< high frequency circuit, liquid crystal antenna >

The substrate of the present invention is suitable for a circuit substrate of a high frequency device (electronic device) such as a semiconductor device used in communication equipment such as a mobile phone, a smartphone, a portable information terminal, and a Wi-Fi device, a circuit substrate of a radar component such as a Surface Acoustic Wave (SAW) device and a radar transceiver, and a substrate of an antenna component such as a liquid crystal antenna, and is particularly suitable for a high frequency circuit and a substrate for a liquid crystal antenna used in a high frequency device because dielectric loss of a high frequency signal can be reduced and stable characteristics can be obtained in a wide temperature range.

Among these, the substrate for a high-frequency circuit is suitable for a high-frequency device that processes a high-frequency signal, particularly a high-frequency signal exceeding 30GHz, and further a high-frequency signal of 35GHz or more. By using the substrate of the present invention as a substrate for a high-frequency circuit of the high-frequency device, transmission loss of a high-frequency signal can be reduced, and characteristics such as quality and strength of the high-frequency signal can be improved.

Further, the substrate is also suitable as a substrate for forming a hole using a laser or the like, and not only improves the characteristics such as quality and strength of the high-frequency signal, but also has high resistance to thermal shock during forming a hole.

Fig. 1 shows an example of a configuration (cross-sectional view) of a high-frequency circuit used in a high-frequency device, and a circuit board 1 includes: a substrate 2 having insulation, a 1 st wiring layer 3 formed on a 1 st main surface 2a of the substrate 2, and a 2 nd wiring layer 4 formed on a 2 nd main surface 2b of the substrate 2. The 1 st and 2 nd wiring layers 3 and 4 are formed with microstrip lines as an example of transmission lines. The 1 st wiring layer 3 constitutes a signal wiring, and the 2 nd wiring layer 4 constitutes a ground wiring. However, the structure of the 1 st and 2 nd wiring layers 3 and 4 is not limited to this, and the wiring layers may be formed only on one of the main surfaces of the substrate 2.

The 1 st and 2 nd wiring layers 3 and 4 are formed of a conductor and have a thickness of usually about 0.1 to 50 μm. The conductors forming the 1 st and 2 nd wiring layers 3 and 4 are not particularly limited, and for example, metals such as copper, gold, silver, aluminum, titanium, chromium, molybdenum, tungsten, platinum, and nickel, alloys containing at least one of these metals, metal compounds, and the like can be used.

The structure of the 1 st and 2 nd wiring layers 3 and 4 is not limited to one layer, and may have a multilayer structure such as a laminated structure of a titanium layer and a copper layer. The method for forming the 1 st and 2 nd wiring layers 3 and 4 is not particularly limited, and various known forming methods such as printing, dipping, plating, vapor deposition, and sputtering using a conductive paste can be applied.

By using the substrate of the present invention for a high-frequency circuit, transmission loss at high frequencies of the circuit substrate can be reduced. Specifically, for example, the transmission loss at the frequency of 35GHz can be reduced to preferably 1dB/cm or less, more preferably 0.5dB/cm or less. Therefore, the quality, strength, and other characteristics of the high-frequency signal, particularly the high-frequency signal exceeding 30GHz, and more particularly the high-frequency signal of 35GHz or more can be maintained, and therefore, a substrate and a circuit substrate suitable for a high-frequency device that processes such a high-frequency signal can be provided. This improves the characteristics and quality of a high-frequency device that processes a high-frequency signal.

Further, since the substrate of the present invention can obtain stable characteristics in a wide temperature range, it can be applied to a high-frequency device used in a tropical region, a cold region, and a region where temperature changes are severe such as a desert.

In addition, as the high-frequency circuit board, there are boards called a general-purpose board, a perforated board, and the like, and for example, a through hole having a regular pattern (lattice shape or the like) and a pad (ランド) of a copper foil are formed on an insulating board of a base material, and a wiring of the copper foil connecting a plurality of the pads is formed by etching. For forming the through hole and etching, a laser is used, and examples of the laser include an excimer laser, an infrared laser, and CO₂Laser, UV laser, etc.

A liquid crystal antenna is an antenna for satellite communication that uses liquid crystal technology and can control the direction of radio waves transmitted and received, and is mainly applied to vehicles such as ships, airplanes, and automobiles. The liquid crystal antenna is assumed to be mainly used outdoors, and therefore, stable characteristics in a wide temperature region are required. Examples of the wide temperature range include a temperature difference between the ground and the sky, a temperature difference between day and night in a desert, squall in a burning desert, use in a tropical region, use in a cold region, and the like.

The substrate of the present invention can provide stable characteristics even in a wide temperature range as described above, and therefore, is preferably used for a liquid crystal antenna.