Photosensitive glass
The present invention relates to a photosensitive glass in which a Li 2 SiO 3 crystal is precipitated by exposure and heat treatment, in which the photosensitive glass has a value of Formula (A) described below of 0.50 or more and 0.75 or less, and the photosensitive glass has a dielectric loss tangent at 20° C. and 10 GHz of 0.0090 or less, [Li 2 O]/([Li 2 O]+[Na 2 O]+[K 2 O]) Formula (A), in Formula (A), [Li 2 O], [Na 2 O], and [K 2 O] respectively indicate contents of Li 2 O, Na 2 O, and K 2 O in the photosensitive glass in terms of mole percentage based on oxides.
1 . A photosensitive glass in which a Li 2 SiO 3 crystal is precipitated by exposure and heat treatment, wherein
the photosensitive glass has a value of Formula (A) described below of 0.50 or more and 0.75 or less, and
the photosensitive glass has a dielectric loss tangent at 20° C. and 10 GHz of 0.0090 or less,
[Li 2 O]/([Li 2 O]+[Na 2 O]+[K 2 O]) Formula (A),
in Formula (A), [Li 2 O], [Na 2 O], and [K 2 O] respectively indicate contents of Li 2 O, Na 2 O, and K 2 O in the photosensitive glass in terms of mole percentage based on oxides.
2 . The photosensitive glass according to claim 1 , comprising:
65% to 78% of SiO 2 in terms of mass percentage based on oxides, wherein
the photosensitive glass has a glass portion etching rate obtained by Formula (1) described below of 2.75 or less when a glass sample having a length of 30 mm×a width of 20 mm and a thickness of 0.5 mmt is immersed in 55 ml of an etching solution at 40° C. containing 5 mass % of HF and 0.7 mass % of HNO 3 for 4 minutes,
[
Math
.
1
]
etching
rate
(
µm
min
)
=
weight
loss
(
g
)
×
thickness
of
glass
before
testing
(
µm
)
weight
of
glass
before
testing
(
g
)
×
test
time
(
min
)
(
1
)
3 . The photosensitive glass according to claim 1 , comprising, in terms of mass percentage based on oxides:
0% to 5% (not including 5%) of Al 2 O 3 ;
5% to 15% of Li 2 O;
3% to 12% of Na 2 O;
3% to 12% of K 2 O;
0.3% to 8% of ZnO;
0.01% to 1% (not including 1%) of Sb 2 O 3 ;
0.001% to 0.1% of CeO 2 ; and
0.05% to 1% of Ag 2 O.
4 . The photosensitive glass according to claim 1 , comprising, in terms of mass percentage based on oxides:
0% to 5% (not including 5%) of Al 2 O 3 ;
5% to 15% of Li 2 O;
3% to 12% of Na 2 O;
3% to 12% of K 2 O;
0% to 8% of ZnO;
0.01% to 1% (not including 1%) of Sb 2 O 3 ;
0.001% to 0.1% of CeO 2 ; and
0.05% to 1% of Ag 2 O.
5 . The photosensitive glass according to claim 1 , comprising:
0% to 8% of B 2 O 3 in terms of mass percentage based on oxides.
6 . The photosensitive glass according to claim 1 , having a relative permittivity at 20° C. and 10 GHz of 7.5 or less.
7 . A glass in which a Li 2 SiO 3 crystal is precipitated by exposing and heat-treating the photosensitive glass according to claim 1 .
8 . A glass in which a microstructure is formed by exposing, heat-treating, and etching the photosensitive glass according to claim 1 .
9 . A circuit substrate comprising an insulating substrate containing the glass according to claim 8 .
10 . The circuit substrate according to claim 9 , which is used for a high-frequency device.
11 . The circuit substrate according to claim 10 , comprising a transmission line.
12 . The circuit substrate according to claim 11 , wherein
the transmission line is a waveguide, a substrate integrated waveguide (SIW), or a microstrip line.
13 . The circuit substrate according to claim 11 , having a function of a passive device.
14 . A high-frequency device comprising the circuit substrate according to claim 9 .
15 . A manufacturing method of a glass in which a microstructure is formed, the method comprising:
a step of exposing the photosensitive glass according to claim 1 ;
a step of precipitating a Li 2 SiO 3 crystal by heat-treating the exposed photosensitive glass; and
a step of removing the precipitated Li 2 SiO 3 crystal by etching treatment.
16 . The manufacturing method according to claim 15 , wherein
the heat treatment comprises holding in a first temperature range and holding in a second temperature range,
the first temperature range is 400° C. or higher and 500° C. or lower, and a holding time in the first temperature range is 15 minutes or longer, and
the second temperature range is 500° C. or higher and 700° C. or lower, and a holding time in the second temperature range is 15 minutes or longer.
17 . The manufacturing method according to claim 15 , wherein
the heat treatment comprises holding in a first temperature range and holding in a second temperature range,
the first temperature range is 400° C. or higher and 600° C. or lower, and a holding time in the first temperature range is 1 minute or longer, and
the second temperature range is (the first temperature range+5° C.) or higher and (the first temperature range+300° C.) or lower, and a holding time in the second temperature range is 1 minute or longer.
18 . The photosensitive glass according to claim 1 , having a transmittance (1 mmt converted value) at 430 nm of 4% or more when exposed at an exposure amount of 0.5 J/cm 2 and heat-treated at 485° C. for 5 hours.
19 . The photosensitive glass according to claim 1 , wherein
regarding a transmittance (1 mmt converted value) at 430 nm measured when exposed at an exposure amount of 1 J/cm 2 to 10 J/cm 2 and heat-treated at 485° C. for 5 hours, when plotted on a coordinate plane in which the exposure amount is set as a horizontal axis (J/cm 2 ) and the transmittance is set as a vertical axis (%), a slope of the transmittance (1 mmt converted value) at 430 nm, which is obtained by Formula (4) described below, is −0.12 or less with respect to the exposure amount of 1 J/cm 2 to 10 J/cm 2 ,
[
Math
.
2
]
slope
=
∑
(
X
-
sample
average
of
X
)
(
Y
-
sample
average
of
Y
)
∑
(
X
-
sample
average
of
X
)
2
,
(
4
)
where X indicates the exposure amount (J/cm 2 ), and Y indicates the transmittance (1 mmt converted value) at 430 nm.