Glass substrate, liquid crystal antenna and high-frequency device
Provided is a glass substrate with which it is possible to reduce dielectric loss in high-frequency signals, and which also has excellent thermal shock resistance. This invention satisfies the relation {Young's modulus (GPa)×average thermal expansion coefficient (ppm/° C.) at 50-350° C.}≤300 (GPa·ppm/° C.), wherein the relative dielectric constant at 20° C. and 35 GHz does not exceed 10, and the dielectric dissipation factor at 20° C. and 35 GHz does not exceed 0.006.
1. A glass substrate comprising, in mole percentage on an oxide basis:
40% to 75% of SiO 2 ;
0.5% to 15% of Al 2 O 3 ;
0.1% to 9% of MgO;
0% to 5% of CaO;
0% to 23% B 2 O 3 ;
Al 2 O 3 and B 2 O 3 in a total amount of 1-37%,
having a content molar ratio represented by {Al 2 O 3 /(Al 2 O 3 +B 2 O 3 )} of 0.01-0.45,
Na 2 O+K 2 O in a total amount of 0.001-5%,
having a content molar ratio represented by {Na 2 O/(Na 2 O+K 2 O)} of 0.01-0.99, and
comprising one or more alkaline-earth metal oxides in a total amount of 0.1-13%,
wherein the glass substrate satisfies the following relationship:
{[Young's modulus (GPa)]×[average coefficient of thermal expansion at 50-350° C. (ppm/° C.)]}≤300 (GPa·ppm/° C.), and
has a relative permittivity as measured at 20° C. and 35 GHz of 10 or less and a dielectric loss tangent as measured at 20° C. and 35 GHz of 0.006 or less.
2. The glass substrate according to claim 1 , comprising Al 2 O 3 in an amount of 0.5-10% and B 2 O 3 in an amount of 9-30% in mole percentage on an oxide basis.
3. The glass substrate according to claim 1 , comprising Fe in an amount of 0-0.012% in terms of Fe 2 O 3 in mole percentage on an oxide basis.
4. The glass substrate according to claim 1 , having a content molar ratio represented by {Na 2 O/(Na 2 O+K 2 O)} of 0.67-0.99, among the alkali metal oxides.
5. The glass substrate according to claim 1 , satisfying the following relationship of contents in mole percentage on an oxide basis:
{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.
6. The glass substrate according to claim 1 , having the Young's modulus of 70 GPa or less.
7. The glass substrate according to claim 1 , having the average coefficient of thermal expansion at 50-350° C. of 5 ppm/° C. or less.
8. The glass substrate according to claim 1 , having a relative permittivity as measured at 20° C. and 10 GHz of 10 or less and a dielectric loss tangent as measured at 20° C. and 10 GHz of 0.006 or less.
9. The glass substrate according to claim 1 , having a Vickers hardness of 400-550.
10. The glass substrate according to claim 1 , having a cracking load of higher than 1.96 N.
11. The glass substrate according to claim 1 , having a density of 2.5 g/cm 3 or less.
12. The glass substrate according to claim 1 , having a porosity of 0.1% or less.
13. The glass substrate according to claim 1 , having a transmittance for light having 350-nm wavelength of 50% or higher.
14. The glass substrate according to claim 1 , having a β-OH value of 0.05 mm −1 to 0.8 mm −1 .
15. The glass substrate according to claim 1 , having an area of a main surface of 100 cm 2 -100,000 cm 2 and a thickness of 0.01 mm-2 mm.
16. The glass substrate according to claim 1 , wherein at least a part of an end surface thereof is chamfered.
17. The glass substrate according to claim 1 , having a compressive stress layer formed in at least a part of a surface of the main surface.
18. The glass substrate according to claim 1 , which is for use in a liquid-crystal antenna or a high-frequency circuit.
19. A liquid-crystal antenna comprising the glass substrate according to claim 1 .
20. A high-frequency device comprising the glass substrate according to claim 1 .