Glass substrate and glass substrate for high frequency device
A glass substrate includes a plurality of through holes that penetrate from a first surface to a second surface of the glass substrate. Each through hole has an upper aperture with a first diameter on the first surface and a lower aperture with a second diameter on the second surface. For each of ten through holes selected from the plurality of through holes, a side wall length is obtained from the first and second diameters and the thickness of the glass substrate, and an R value is obtained by dividing the side wall length by the thickness of the glass substrate. The R values fall within a range of 1 to 1.1. A B value, obtained from dividing a difference between the greatest R value and the smallest R value by an average of the R values followed by multiplication with 100, is 5% or less.
1. A glass substrate comprising:
a first surface;
a second surface; and
a plurality of through holes that penetrate from the first surface to the second surface,
wherein each of the through holes has an upper aperture with a diameter ϕ 1 on the first surface, and a lower aperture with a diameter ϕ 2 on the second surface,
wherein selected through holes are ten through holes randomly selected from the plurality of through holes,
wherein a straight type through hole is a selected through hole, in which a constricted part with a diameter being less than a smaller diameter from among the diameter ϕ 1 and the diameter ϕ 2 is absent, and
an X-type through hole is a selected through hole, in which a constricted part with a diameter ϕ 3 being less than a smaller diameter from among the diameter ϕ 1 and the diameter ϕ 2 is present,
wherein, for each of the selected through holes, in a cross section of the selected through hole cut along an axis of expansion of the selected through hole, an approximated length L of a side wall is
[
Math
1
]
L
=
t
2
+
(
ϕ
1
-
ϕ
2
2
)
2
formula
(
1
)
when the selected through hole is a straight type through hole, and
[
Math
2
]
L
=
(
t
2
)
2
+
(
ϕ
1
-
ϕ
3
2
)
2
+
(
t
2
)
2
+
(
ϕ
2
-
ϕ
3
2
)
2
formula
(
2
)
when the selected through hole is an X-type through hole, where t is a thickness of the glass substrate,
wherein R values each expressed by a ratio of the approximate length of the side wall to the thickness of the glass substrate, L/t, fall within a range of 1 to 1.1, and
wherein a B value obtained by
[
Math
3
]
B
=
R
max
-
R
min
R
ave
×
100
formula
(
3
)
where R ave is an average of the R values of the selected through holes, R max is a maximum of the R values of the selected through holes, and R min is a minimum of the R values of the selected through holes, is 5% or less.
2. The glass substrate according to claim 1 ,
wherein the B value is 2% or less.
3. The glass substrate according to claim 1 ,
wherein the R values fall within a range of 1 to 1.05.
4. The glass substrate according to claim 1 ,
wherein the thickness of the glass substrate falls within a range of 0.05 mm to 0.8 mm.
5. The glass substrate according to claim 1 ,
wherein the diameter ϕ 1 falls within a range of 10 μm to 200 μm, and
wherein the diameter ϕ 2 falls within a range of 5 μm to 150 μm.
6. The glass substrate according to claim 2 ,
wherein the R values fall within a range of 1 to 1.05.
7. The glass substrate according to claim 2 ,
wherein the thickness of the glass substrate falls within a range of 0.05 mm to 0.8 mm.
8. The glass substrate according to claim 2 ,
wherein the diameter ϕ 1 falls within a range of 10 μm to 200 μm, and
wherein the diameter ϕ 2 falls within a range of 5 μm to 150 μm.
9. The glass substrate according to claim 3 ,
wherein the thickness of the glass substrate falls within a range of 0.05 to 0.8 mm.
10. The glass substrate according to claim 3 ,
wherein the diameter ϕ 1 falls within a range of 10 μm to 200 μm, and
wherein the diameter ϕ 2 falls within a range of 5 μm to 150 μm.
11. The glass substrate according to claim 4 ,
wherein the diameter ϕ 1 falls within a range of 10 μm to 200 μm, and
wherein the diameter ϕ 1 falls within a range of 5 μm to 150 μm.
12. A glass substrate for a high frequency device, comprising:
the glass substrate according to claim 1 .