Mesa-shaped piezoelectric resonator element
View Patent ↗A mesa-shaped piezoelectric resonator element including a resonator section having a thicker thickness than a peripheral section on the board surface of a piezoelectric substrate formed in a rectangular shape, wherein, when the length of the long side of the piezoelectric substrate is x and the board thickness of the resonator section is t, etching depth y of a level-difference section is set to fulfill a relationship in the following equation, based on the board thickness t. y = - 1.32 × ( x t ) + 43 ± 5 ( % )
1. A resonator element, comprising:
a resonator section having a thicker thickness than a peripheral section on the board surface of a substrate formed in a rectangular shape, wherein the resonator section resonates with thickness shear vibration,
when the length of the long side of the substrate is x and the board thickness of the resonator section is t, y being set to fulfill a relationship in the following equation, based on the board thickness t,
y
=
-
1.32
×
(
x
t
)
+
43
±
5
(
%
)
,
y being the percentage value of a difference between the board thickness t and the thickness of the peripheral section over the board thickness t, and
a level-difference being between the resonator section and the peripheral section, and the resonator section and the peripheral section being connected by a level-difference surface, wherein the level-difference surface is positioned at a maximum amplitude of a flexural mode occurring along a displacement direction of the thickness shear vibration in the substrate.
2. The resonator element according to claim 1 , wherein
y
=
-
1.32
×
(
x
t
)
+
43
±
1.8
(
%
)
.
3. The resonator element according to claim 1 , wherein x/t≦30.
4. The resonator element according to claim 1 , wherein x/t≦19.8.
5. The resonator element according to claim 1 , wherein the level-difference surface has one level.
6. The resonator element according to claim 3 , wherein the level-difference surface has one level.
7. The resonator element according to claim 4 , wherein the level-difference surface has one level.
8. The resonator element according to claim 2 , wherein x/t≦30.
9. The resonator element according to claim 2 , wherein x/t≦19.8.
10. The resonator element according to claim 2 , wherein the level-difference surface has one level.
11. The resonator element according to claim 8 , wherein the level-difference surface has one level.
12. The resonator element according to claim 9 , wherein the level-difference surface has one level.