Glass substrate for high-frequency device and circuit board for high-frequency device
The present invention relates to a glass substrate for a high-frequency device, which includes SiO 2 as a main component, the glass substrate having a total content of alkali metal oxides in the range of 0.001-5% in terms of mole percent on the basis of oxides, the alkali metal oxides having a molar ratio represented by Na 2 O/(Na 2 O+K 2 O) in the range of 0.01-0.99, and the glass substrate having a total content of Al 2 O 3 and B 2 O 3 in the range of 1-40% in terms of mole percent on the basis of oxides and having a molar ratio represented by Al 2 O 3 /(Al 2 O 3 +B 2 O 3 ) in the range of 0-0.45, in which at least one main surface of the glass substrate has a surface roughness of 1.5 nm or less in terms of arithmetic average roughness Ra, and the glass substrate has a dielectric dissipation factor at 35 GHz of 0.007 or less.
1. A glass substrate, which comprises SiO 2 as a main component, the glass substrate having a total content of alkali metal oxides in the range of 0.001-5% in terms of mole percent on the basis of oxides, the alkali metal oxides having a molar ratio represented by Na 2 O/(Na 2 O+K 2 O) in the range of 0.01-0.99, and the glass substrate having a total content of Al 2 O 3 and B 2 O 3 in the range of 16-40% in terms of mole percent on the basis of oxides and having a molar ratio represented by Al 2 O 3 /(Al 2 O 3 +B 2 O 3 ) in the range of 0-0.45,
wherein the glass substrate comprises, in terms of mole percent on the basis of oxides:
SiO 2 40-75%;
Al 2 O 0-15%;
B 2 O 3 16-30%;
MgO 0-13%;
CaO 0-13%;
SrO 3-13%;
BaO 0-10%,
wherein at least one main surface of the glass substrate has a surface roughness of 1.5 nm or less in terms of arithmetic average roughness Ra, and the glass substrate has a dielectric dissipation factor at 35 GHz of 0.007 or less.
2. The glass substrate according to claim 1 , which has a content of Al 2 O 3 in the range of 0-10%, in terms of mole percent on the basis of oxides.
3. The glass substrate according to claim 1 , which has a content of Fe, in terms of Fe 2 O 3 , of 0.012% or less in terms of mole percent on the basis of oxides.
4. The glass substrate according to claim 1 , which has a β-OH value in the range of 0.05-0.6 mm −1 .
5. The glass substrate according to claim 1 , which has a relative permittivity at 35 GHz of 10 or less.
6. The glass substrate according to claim 1 , which has an average thermal expansion coefficient over the range of from 50° C. to 350° C. in the range of 3-15 ppm/° C.
7. The glass substrate according to claim 1 , which has a Young's modulus of 40 GPa or higher.
8. The glass substrate according to claim 1 , which has a porosity of 0.1% or less.
9. The glass substrate according to claim 1 , which has a transmittance at 350-nm wavelength of 50% or higher.
10. The glass substrate according to claim 1 , which has a thickness in the range of 0.05-1 mm and a substrate area in the range of 225-10,000 cm 2 .
11. The glass substrate according to claim 1 , which is amorphous.
12. A circuit board for a high-frequency device, comprising:
the glass substrate according to claim 1 ; and
a wiring layer formed on the main surface of the glass substrate,
wherein the circuit board has a transmission loss at 35 GHz of 1 dB/cm or less.
13. The glass substrate according to claim 1 , which has a content of B 2 O 3 in the range of 16-24%, in terms of mole percent on the basis of oxides.
14. The glass substrate according to claim 1 , which has a content of B 2 O 3 in the range of 16-23%, in terms of mole percent on the basis of oxides.
15. The glass substrate according to claim 1 , which has a content of CaO in the range of 0-5%, in terms of mole percent on the basis of oxides.