Piezoelectric diaphragm and piezoelectric vibration device

Abstract

In a crystal diaphragm (10), a holding part (13) has a pair of vibration holding parts (13a) along a first virtual straight line (L1) in an X-axis direction that passes through a center point (C1) in plan view of a vibration part (11), and a pair of outer frame holding parts (13b) that extend in a Z'-axis direction and respectively connect each of the vibration holding parts (13a) to two points of an outer frame part (12). Each vibration holding part (13a) connects the vibration part (11) and the outer frame holding part (13b), the outer frame holding part (13b) connects the vibration holding part (13a) and the outer frame part (12), a first through-hole (12g) penetrating in the thickness direction is formed in the outer frame part (12), and the first through-hole (12g) is located on the extension line of the outer frame holding part (13b).

Description

Piezoelectric diaphragm and piezoelectric vibration device

[0001] The present invention relates to a piezoelectric vibration plate and a piezoelectric vibration device including the same.

[0002] Conventionally, so-called sandwich-structured piezoelectric vibration devices have been known as piezoelectric vibration devices suitable for miniaturization and low height. The housing of a sandwich-structured piezoelectric vibration device is configured as a roughly rectangular parallelepiped package. This package is composed of first and second sealing members made of, for example, glass or quartz, and a piezoelectric vibration plate with excitation electrodes formed on both main surfaces. The first and second sealing members are stacked and bonded via the piezoelectric vibration plate. The vibration portion of the piezoelectric vibration plate disposed inside the package (internal space) is hermetically sealed by the first and second sealing members (see, for example, Patent Document 1).

[0003] In the piezoelectric vibration device described in Patent Document 1, the piezoelectric vibration plate includes a vibration part having an excitation electrode formed on a main surface thereof, an outer frame part surrounding the outer peripheral wall of the vibration part, a holding part connecting the outer peripheral wall of the vibration part and the inner peripheral wall of the outer frame part, and a cutout part formed by cutting out between the vibration part and the outer frame part in the thickness direction. By providing only one holding part, the device can be made compact while being less susceptible to the effects of external stress transmitted from the outer frame part and vibration leakage of vibration energy from the vibration part.

[0004] Japanese Patent Application Laid-Open No. 2020-141358

[0005] In recent years, as piezoelectric vibration devices have become more accurate, one type of characteristic evaluation has been an acceleration sensitivity evaluation, in which an acceleration that vibrates at a predetermined frequency in three axial directions (X, Y, and Z) of the piezoelectric vibration device is applied and the presence or absence of noise (spurious) signals that are generated as a result is measured. Therefore, there is a demand for piezoelectric vibration devices that satisfy these characteristics. However, when a piezoelectric vibration plate having only one of the above-mentioned holding portions is used, the deflection in the thickness direction (Z direction) of the piezoelectric vibration plate can be large, making it difficult to satisfy acceleration sensitivity evaluations (e.g., G-sensitivity, etc.).

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a piezoelectric vibration plate that can suppress deflection in the thickness direction while suppressing the effects of external stress, etc., and a piezoelectric vibration device equipped with the same.

[0007] The present invention provides a means for solving the above-described problems as follows: That is, the present invention provides a piezoelectric diaphragm that vibrates in a thickness-shear mode, the piezoelectric diaphragm including a vibrating portion having excitation electrodes formed on a main surface thereof, an outer frame portion surrounding the vibrating portion, a retaining portion connecting the vibrating portion and the outer frame portion, and a cutout portion formed by cutting out a portion between the vibrating portion and the outer frame portion in the thickness direction, the retaining portion including a pair of vibration retaining portions along a first imaginary line in a first direction passing through a center point of the vibrating portion in a plan view, and a pair of outer frame retaining portions extending in a direction different from the first direction and connecting each vibration retaining portion to two locations on the outer frame portion, each vibration retaining portion connecting the vibrating portion and the outer frame retaining portion, the outer frame portion having at least one of a through hole penetrating in the thickness direction and a thin portion having a small thickness in the thickness direction formed therein, and at least one of the through hole and the thin portion being located on an extension line of the outer frame retaining portion. More specifically, the present invention relates to a piezoelectric diaphragm that vibrates in a thickness-shear manner, and is configured to include a vibrating portion having an excitation electrode formed on a main surface thereof, an outer frame portion surrounding an outer peripheral wall of the vibrating portion, a holding portion connecting the outer peripheral wall of the vibrating portion and the inner peripheral wall of the outer frame portion, and a cutout portion formed by cutting out in the thickness direction between the vibrating portion and the outer frame portion, and the holding portion includes a pair of vibration holding portions along a first imaginary straight line in a first direction that passes through the center point of the vibrating portion in a plan view, and a pair of vibration holding portions extending in a direction different from the first direction and and a pair of outer frame holding parts that connect each vibration holding part to two points on the inner peripheral wall of the outer frame part, each vibration holding part connects the outer peripheral wall of the vibration part to the outer frame holding part, and the outer frame holding part connects the vibration holding part to the inner peripheral wall of the outer frame part, and the outer frame part has at least one of a through hole that penetrates in the thickness direction and a thin-walled part that is thin in the thickness direction formed in the outer frame part, and at least one of the through hole and the thin-walled part is located on an extension line of the outer frame holding part.

[0008] According to the above configuration, a pair of vibration retainers are connected to both ends of the vibrating unit in the first direction, and outer frame retainers extending in the second axial direction are connected to four locations on the outer frame, thereby suppressing the effects of external stress and suppressing deflection of the piezoelectric diaphragm in the thickness direction. Specifically, by forming the vibration retainers along a first virtual line in the first direction (e.g., the longitudinal direction) passing through the center point of the vibrating unit in a planar view, displacement of the vibrating unit in the thickness direction can be effectively suppressed with as few points as possible. By supporting the vibrating unit with the vibration retainers and outer frame retainers extending in different directions, displacement of the vibrating unit in the first direction and directions other than the first direction can be effectively suppressed with as few points as possible. Because the vibrating unit is supported by only two retaining parts, the vibration retainers and outer frame retainers extending in different directions, there is no unnecessary reduction in the effective area of ​​the vibrating unit.

[0009] Furthermore, by forming the vibration retaining portion along a first imaginary line connecting the center point of the vibrating portion in a plan view and the center of the extension direction of each outer frame retaining portion, the stress transmitted from the outer frame retaining portion to the vibrating portion can be made uniform, thereby suppressing unbalanced transmission of stress to the vibrating portion. Furthermore, the through-holes and thin-walled portions provided in the outer frame portion can inhibit the transmission of vibration at the connection portion between the outer frame retaining portion of the retaining portion and the outer frame portion, thereby reducing vibration leakage from the retaining portion (outer frame retaining portion) to the outer frame portion. Moreover, the through-holes and thin-walled portions can alleviate stress due to external impact, thereby suppressing the transmission of external stress from the outer frame portion to the retaining portion (outer frame retaining portion).

[0010] In the piezoelectric diaphragm having the above configuration, it is preferable that the outer frame holding portion is formed in line symmetry with respect to the first imaginary line and in line symmetry with respect to a second imaginary line along a second direction perpendicular to the first imaginary line. With this configuration, stress transmitted from the outer frame portion to the vibration holding portion can be made uniform, and unbalanced transmission of stress to the vibration holding portion can be suppressed.

[0011] In the piezoelectric diaphragm having the above configuration, when the through holes are formed in the outer frame portion, it is preferable that the inner wall surfaces of the through holes have through electrodes formed thereon to electrically connect the front and back main surfaces of the outer frame portion. Here, if electrical wiring is formed on the inner peripheral wall of the outer frame portion, there is a possibility that it may come into contact with the outside and be broken, but by using the through electrodes of the through holes as electrical wiring, such breaking can be prevented.

[0012] In the piezoelectric diaphragm having the above configuration, when the thin-walled portion is formed in the outer frame portion, it is preferable that the thin-walled portion has a wiring electrode formed therein that passes through a step formed in the outer frame portion. With this configuration, since the thin-walled portion is disposed between the outer frame holding portion and the outer frame portion, breaking of the wiring electrode can be suppressed by changing the shape of the step.

[0013] In the piezoelectric diaphragm having the above configuration, the piezoelectric diaphragm is preferably an AT-cut quartz crystal diaphragm, in which case the lead wires extending from the excitation electrodes of the vibrating portion along the X-axis direction can be prevented from breaking.

[0014] The present invention also provides a piezoelectric vibration device including the piezoelectric diaphragm having the above-described configuration, wherein an upper sealing plate that covers the upper surface of the piezoelectric diaphragm and a lower sealing plate that covers the lower surface of the piezoelectric diaphragm are bonded to the piezoelectric diaphragm. The piezoelectric vibration device having the above-described configuration can achieve the same effects as the piezoelectric diaphragm described above.

[0015] According to the piezoelectric vibration plate and piezoelectric vibration device of the present invention, a pair of vibration retaining parts are connected to both ends of the vibration part in the first direction, and outer frame retaining parts extending in the second direction are connected to four points of the outer frame part, so that the effects of external stress, etc. can be suppressed and deflection in the thickness direction of the piezoelectric vibration plate can be suppressed.

[0016] FIG. 1 is a schematic diagram illustrating a crystal unit according to this embodiment. FIG. 2 is a schematic plan view of the first main surface side of a first sealing member of the crystal unit. FIG. 3 is a schematic plan view of the second main surface side of the first sealing member of the crystal unit. FIG. 4 is a schematic plan view of the first main surface side of a crystal unit according to this embodiment. FIG. 5 is a schematic plan view of the second main surface side of a crystal unit according to this embodiment. FIG. 6 is a schematic plan view of the first main surface side of a second sealing member of the crystal unit. FIG. 7 is a schematic plan view of the second main surface side of the second sealing member of the crystal unit. FIG. 8 is a view equivalent to FIG. 4 of a crystal unit according to another embodiment 1. FIG. 9 is a view equivalent to FIG. 4 of a crystal unit according to another embodiment 2. FIG. 10 is a view equivalent to FIG. 5 of a crystal unit according to another embodiment 2. FIG. 11 is a view equivalent to FIG. 4 of a crystal unit according to another embodiment 3. FIG. 12 is a view equivalent to FIG. 5 of a crystal unit according to another embodiment 3.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following preferred embodiments, a piezoelectric resonator device to which the present invention is applied is a quartz resonator.

[0018] First, the basic structure of the quartz crystal unit 100 according to this embodiment will be described. As shown in FIG. 1 , the quartz crystal unit 100 is configured to include a quartz crystal vibrating plate (piezoelectric vibrating plate) 10, a first sealing member (top sealing plate) 20, and a second sealing member (bottom sealing plate) 30. In this quartz crystal unit 100, the quartz crystal vibrating plate 10 is bonded to the first sealing member 20, and the quartz crystal vibrating plate 10 is bonded to the second sealing member 30, thereby forming a package with a substantially rectangular parallelepiped sandwich structure. That is, in the quartz crystal unit 100, the first sealing member 20 and the second sealing member 30 are bonded to both main surfaces of the quartz crystal vibrating plate 10, respectively, to form an internal space (cavity) of the package, and the vibrating unit 11 (see FIGS. 4 and 5 ) is hermetically sealed in this internal space.

[0019] The crystal unit 100 according to this embodiment has a package size of, for example, 1.0 × 0.8 mm, and is designed to be compact and low-profile. The crystal unit 100 is electrically connected to an external circuit board (not shown) via solder or the like.

[0020] Next, the quartz crystal plate 10, the first sealing member 20, and the second sealing member 30 of the quartz crystal unit 100 will be described with reference to Figures 1 to 7. Note that the description here focuses on the individual components that are not bonded together and are configured as individual components. Figures 2 to 7 merely show one example of the configuration of the quartz crystal plate 10, the first sealing member 20, and the second sealing member 30, and are not intended to limit the scope of the present invention.

[0021] As shown in Figures 4 and 5, the quartz crystal vibrating plate 10 is a piezoelectric substrate made of quartz crystal, and both of its main surfaces (first main surface 101 and second main surface 102) are formed as flat, smooth surfaces (mirror-finished). In this embodiment, an AT-cut quartz crystal plate that performs thickness-shear vibration is used as the quartz crystal vibrating plate 10. In the quartz crystal vibrating plate 10 shown in Figures 4 and 5, both main surfaces 101 and 102 of the quartz crystal vibrating plate 10 are in the XZ' plane. In this XZ' plane, the direction parallel to the short side (short side direction) of the quartz crystal vibrating plate 10 is the X-axis direction, and the direction parallel to the long side (long side direction) of the quartz crystal vibrating plate 10 is the Z'-axis direction. Note that AT-cut is a processing technique in which artificial quartz crystal is cut at an angle of approximately 35°15' around the X-axis with respect to the Z-axis, one of the three crystal axes of the artificial quartz crystal: the electrical axis (X-axis), the mechanical axis (Y-axis), and the optical axis (Z-axis). In an AT-cut quartz plate, the X-axis coincides with the crystal axis of the quartz. The Y'-axis and Z'-axis coincide with axes tilted approximately 35°15' from the Y-axis and Z-axis, respectively (these cutting angles may be slightly changed within the range required to adjust the frequency-temperature characteristics of the AT-cut quartz plate). The Y'-axis and Z'-axis directions correspond to the cutting direction when the AT-cut quartz plate is cut. Note that the cutting angle may be slightly tilted depending on the characteristics.

[0022] A pair of excitation electrodes (first excitation electrode 111 and second excitation electrode 112) are formed on both main surfaces 101 and 102 of the quartz crystal vibration plate 10. The quartz crystal vibration plate 10 includes a substantially rectangular vibrating portion 11, an outer frame portion 12 surrounding the outer peripheral wall of the vibrating portion 11, a holding portion 13 connecting the outer peripheral wall of the vibrating portion 11 to the inner peripheral wall of the outer frame portion 12, and cutouts 14a and 14b formed by cutting out portions in the thickness direction between the vibrating portion 11 and the outer frame portion 12. The inner peripheral wall of the outer frame portion 12 and the outer peripheral wall of the vibrating portion 11 are both rectangular in plan view. Furthermore, the long side of the quartz crystal vibration plate 10 and the long side of the inner peripheral wall of the outer frame portion 12 are orthogonal in plan view, and the long side of the inner peripheral wall of the outer frame portion 12 and the long side of the vibrating portion 11 are aligned in the same direction in plan view. The vibration section 11 is formed so that an outer peripheral portion 11b side, where the first excitation electrode 111 and the second excitation electrode 112 are not formed, is thicker than a central portion 11a side, where the first excitation electrode 111 and the second excitation electrode 112 are formed, and annular steps (step portions) 11c are formed on both main surfaces of the vibration section 11. One holding portion 13 is provided on each of the +X direction side and the −X direction side of the vibration section 11. The holding portion 13 is composed of a vibration holding portion 13a on the vibration section 11 side and an outer frame holding portion 13b on the outer frame section 12 side. Details of the holding portion 13 will be described later.

[0023] The first excitation electrode 111 is provided on the first main surface 101 side of the vibrating part 11, and the second excitation electrode 112 is provided on the second main surface 102 side of the vibrating part 11. Input / output lead wiring (lead electrodes) for connecting these excitation electrodes to external electrode terminals are connected to the first excitation electrode 111 and the second excitation electrode 112. The first input lead wiring 113 is led out from the first excitation electrode 111 toward the +X direction and connected to a connection bonding pattern 12b formed on the first main surface 101 side of the outer frame part 12 via a holding part 13 provided on the +X direction side of the vibrating part 11. The outer frame part 12 is formed thicker than the holding part 13, and a step is formed between the outer frame part 12 and the holding part 13. Therefore, the first lead wiring 113 is connected to the connection bonding pattern 12b via internal wiring 17 formed on the inner circumferential wall of the outer frame part 12. The internal wiring 17 is provided on the inner peripheral wall of the outer frame portion 12 that is along the X-axis direction and is on the +Z' direction side.

[0024] The second output wiring 114 is drawn out from the second excitation electrode 112 toward the −X direction and connected to the connection bonding pattern 12e formed on the second main surface 102 side of the outer frame portion 12 via the holding portion 13 provided on the −X direction side of the vibration portion 11. As described above, a step is formed between the outer frame portion 12 and the holding portion 13, and the second output wiring 114 is connected to the connection bonding pattern 12e via the internal wiring 18 formed on the inner circumferential wall of the outer frame portion 12. The connection bonding pattern 12e is connected to the connection bonding pattern 12a formed on the first main surface 101 side of the outer frame portion 12 via a penetrating electrode of a second through-hole 12h formed in the outer frame portion 12. The internal wiring 18 is provided on the inner circumferential wall of the outer frame portion 12 that is along the X axis direction and is on the −Z′ direction side. In this embodiment, the first escape wiring 113 and the second escape wiring 114 are escaped in different directions, so that the escape wirings are not arranged opposite each other across the vibration unit 11 in the vibration unit 11. This eliminates unnecessary excitation by the escape wiring in the vibration unit 11, and improves the stability of the characteristics.

[0025] Both main surfaces (first main surface 101, second main surface 102) of the quartz crystal vibrating plate 10 are provided with diaphragm-side sealing portions for bonding the quartz crystal vibrating plate 10 to the first sealing member 20 and the second sealing member 30. A first diaphragm-side bonding pattern 121 is formed as the diaphragm-side sealing portion on the first main surface 101, and a second diaphragm-side bonding pattern 122 is formed as the diaphragm-side sealing portion on the second main surface 102. The first diaphragm-side bonding pattern 121 and the second diaphragm-side bonding pattern 122 are formed on the outer frame portion 12 and are annular in plan view. The outer peripheral edge of the first diaphragm-side bonding pattern 121 is located adjacent to the outer peripheral edge of the first main surface 101 of the quartz crystal vibrating plate 10 (outer frame portion 12). The outer peripheral edge of the second diaphragm-side bonding pattern 122 is located adjacent to the outer peripheral edge of the second main surface 102 of the quartz crystal vibrating plate 10 (outer frame portion 12). The first diaphragm-side bonding pattern 121 and the second diaphragm-side bonding pattern 122 are connected via internal wiring 19 formed on the inner circumferential wall of the outer frame portion 12. The internal wiring 19 is provided on one of the inner circumferential walls of the outer frame portion 12 that is along the Z'-axis direction and on the inner circumferential wall on the -X direction side, and is provided on the inner circumferential wall that is perpendicular to the inner circumferential wall on which the above-mentioned internal wirings 17 and 18 are provided.

[0026] As shown in FIGS. 4 and 5 , the quartz crystal vibrating plate 10 has five through holes formed between the first main surface 101 and the second main surface 102. Specifically, the four first through holes 12g are provided in the four corner regions of the outer frame portion 12, and the four first through holes 12g are located on the extension lines of the outer frame holding portions 13b of the holding portion 13. The second through holes 12h are provided in the outer frame portion 12 on one side of the vibrating portion 11 in the Z′-axis direction (the −Z′ direction side in FIGS. 4 and 5 ). Around the four through holes 12g, connection bonding patterns 12i are formed on the first main surface 101 side, and connection bonding patterns 12j are formed on the second main surface 102 side. Moreover, around the through-hole 12h, a connection bonding pattern 12a is formed on the first main surface 101 side, and a connection bonding pattern 12e is formed on the second main surface 102 side.

[0027] The first through-holes 12g and the second through-holes 12h have through-hole electrodes formed along their inner walls to connect the electrodes formed on the first main surface 101 and the second main surface 102. The central portions of the first through-holes 12g and the second through-holes 12h are hollow through-holes that penetrate between the first main surface 101 and the second main surface 102. While the present embodiment illustrates an example in which five through-holes penetrate between the first main surface 101 and the second main surface 102, it is also possible to notch a portion of the side surface of the quartz crystal plate 10 without forming through-holes, and form castellations 12k with electrodes attached on the inner wall surfaces of the notched regions, as shown in FIG. 8 (the same applies to the first sealing member 20 and the second sealing member 30). 8, the first escape routing 113 and the second escape routing 114 are formed on the holding portion 13 of the quartz crystal plate 10, and no escape routing is formed on the first sealing member 20 or the second sealing member 30, so that the first escape routing 113 and the second escape routing 114 can be routed along the shortest possible route. This allows the length of the first escape routing 113 and the second escape routing 114 to be shortened, thereby reducing the resulting parasitic capacitance.

[0028] 2 and 3, the first sealing member 20 is a rectangular parallelepiped substrate formed from a single AT-cut quartz crystal plate, and the second main surface 202 of this first sealing member 20 (the surface that bonds to the quartz crystal vibrating plate 10) is formed as a flat, smooth surface (mirror-finished). Although the first sealing member 20 does not have a vibrating portion, by using an AT-cut quartz crystal plate like the quartz crystal vibrating plate 10, the thermal expansion coefficients of the quartz crystal vibrating plate 10 and the first sealing member 20 can be made the same, thereby suppressing thermal deformation of the quartz crystal unit 100. Furthermore, the orientations of the X-axis, Y-axis, and Z'-axis of the first sealing member 20 are the same as those of the quartz crystal vibrating plate 10.

[0029] As shown in FIG. 2 , first and second wiring terminals 22, 23 and a metal film 28 for shielding (ground connection) are formed on the first main surface 201 of the first sealing member 20 (the outer main surface not facing the quartz crystal plate 10). The first and second wiring terminals 22, 23 are provided as wiring for electrically connecting the first and second excitation electrodes 111, 112 of the quartz crystal plate 10 to the external electrode terminal 32 of the second sealing member 30. The first and second terminals 22, 23 are provided at both ends in the Z′-axis direction, with the first terminal 22 on the +Z′-direction side and the second terminal 23 on the −Z′-direction side. The first and second terminals 22, 23 are formed to extend in the X-axis direction. The first terminal 22 and the second terminal 23 are formed in a substantially rectangular shape.

[0030] The metal film 28 is provided between the first and second terminals 22, 23 and is arranged at a predetermined distance from the first and second terminals 22, 23. The metal film 28 is provided in almost all areas of the first main surface 201 of the first sealing member 20 that do not have the first and second terminals 22, 23. The metal film 28 is provided from the end of the first main surface 201 of the first sealing member 20 in the +X direction to the end in the −X direction.

[0031] 2 and 3, six through holes are formed in the first sealing member 20, penetrating between the first main surface 201 and the second main surface 202. Specifically, four third through holes 211 are provided in the four corner regions of the first sealing member 20. Fourth and fifth through holes 212, 213 are provided in the +Z' direction and the -Z' direction in FIGS. 2 and 3, respectively.

[0032] The third through hole 211 and the fourth and fifth through holes 212, 213 have through electrodes formed along their inner wall surfaces to provide electrical continuity between the electrodes formed on the first main surface 201 and the second main surface 202. The central portions of the third through hole 211 and the fourth and fifth through holes 212, 213 are hollow through-holes that penetrate between the first main surface 201 and the second main surface 202. The through electrodes of two third through holes 211, 211 located diagonally on the first main surface 201 of the first sealing member 20 (the third through hole 211 located at the corner in the +X direction and the +Z' direction in FIGS. 2 and 3 , and the third through hole 211 located at the corner in the -X direction and the -Z' direction) are electrically connected to each other by the metal film 28. Furthermore, the through electrode of the third through hole 211 located at the corner in the −X direction and the +Z′ direction and the through electrode of the fourth through hole 212 are electrically connected by the first terminal 22. The through electrode of the third through hole 211 located at the corner in the +X direction and the −Z′ direction and the through electrode of the fifth through hole 213 are electrically connected by the second terminal 23.

[0033] A sealing member-side first bonding pattern 24 is formed on the second main surface 202 of the first sealing member 20 as a sealing member-side first sealing portion for bonding to the quartz crystal vibration plate 10. The sealing member-side first bonding pattern 24 is formed in a ring shape in a plan view. Furthermore, on the second main surface 202 of the first sealing member 20, connection bonding patterns 25 are formed around the third through holes 211. A connection bonding pattern 261 is formed around the fourth through hole 212, and a connection bonding pattern 262 is formed around the fifth through hole 213. The outer periphery of the sealing member-side first bonding pattern 24 is provided close to the outer periphery of the second main surface 202 of the first sealing member 20.

[0034] 6 and 7, the second sealing member 30 is a rectangular parallelepiped substrate formed from a single AT-cut quartz crystal plate, and the first main surface 301 of this second sealing member 30 (the surface that bonds to the quartz crystal plate 10) is formed as a flat, smooth surface (mirror-finished). Note that the second sealing member 30 also uses an AT-cut quartz crystal plate like the quartz crystal plate 10, and it is desirable that the orientations of the X-axis, Y-axis, and Z'-axis are the same as those of the quartz crystal plate 10.

[0035] A sealing member-side second bonding pattern 31 is formed on the first main surface 301 of the second sealing member 30 as a sealing member-side second sealing portion for bonding to the quartz-crystal vibration plate 10. The sealing member-side second bonding pattern 31 is formed in a ring shape in a plan view. The outer periphery of the sealing member-side second bonding pattern 31 is provided close to the outer periphery of the first main surface 301 of the second sealing member 30.

[0036] Four external electrode terminals 32 are provided on the second main surface 302 of the second sealing member 30 (the outer main surface that does not face the quartz crystal vibrating plate 10), which are electrically connected to an external circuit board provided outside the quartz crystal vibrating device 100. The external electrode terminals 32 are formed in a generally L-shape and are located at four corners (corner portions) of the second main surface 302 of the second sealing member 30. The external electrode terminals 32 are provided in positions that overlap the outer frame portion 12 of the quartz crystal vibrating plate 10 described above in a plan view.

[0037] As shown in FIGS. 6 and 7 , the second sealing member 30 has four through holes formed therein that penetrate between the first main surface 301 and the second main surface 302. Specifically, the four sixth through holes 33 are provided in the four corner regions of the second sealing member 30. In the sixth through holes 33, through-electrodes for establishing electrical continuity between the electrodes formed on the first main surface 301 and the second main surface 302 are formed along the inner wall surfaces of the sixth through holes 33. The through-electrodes formed on the inner wall surfaces of the sixth through holes 33 in this manner establish electrical continuity between the electrodes formed on the first main surface 301 and the external electrode terminals 32 formed on the second main surface 302. The central portions of the sixth through holes 33 form hollow through-holes that penetrate between the first main surface 301 and the second main surface 302. Furthermore, on the first main surface 301 of the second sealing member 30, connection bonding patterns 34 are formed around the sixth through holes 33. Furthermore, on the first main surface 301 of the second sealing member 30, connection bonding patterns 35 are formed.

[0038] In the quartz crystal unit 100 including the quartz crystal vibrating plate 10, first sealing member 20, and second sealing member 30 configured as described above, the quartz crystal vibrating plate 10 and the first sealing member 20 are diffusion bonded together with the diaphragm-side first bonding pattern 121 and the sealing member-side first bonding pattern 24 overlapping each other, and the quartz crystal vibrating plate 10 and the second sealing member 30 are diffusion bonded together with the diaphragm-side second bonding pattern 122 and the sealing member-side second bonding pattern 31 overlapping each other, thereby producing a sandwich-structured package as shown in Fig. 1. This hermetically seals the internal space of the package, i.e., the space housing the vibrating portion 11.

[0039] At this time, the above-mentioned connection bonding patterns are also diffusion bonded while overlapping each other. By bonding the connection bonding patterns together, electrical conduction is obtained between the first excitation electrode 111, the second excitation electrode 112, and the external electrode terminal 32 in the quartz-crystal resonator 100. Specifically, the first excitation electrode 111 is connected to the external electrode terminal 32 via the first extraction wiring 113, the internal wiring 17, the connection bonding pattern 12b, the connection bonding pattern 261, the through electrode of the fourth through hole 212, the first terminal 22, the through electrode of the third through hole 211, the through electrode of the first through hole 12g, and the through electrode of the sixth through hole 33, in this order. The second excitation electrode 112 is connected to the external electrode terminal 32 via the second extraction wiring 114, the internal wiring 18, the connection junction pattern 12e, the through electrode of the second through hole 12h, the connection junction pattern 12a, the connection junction pattern 262, the through electrode of the fifth through hole 213, the second terminal 23, the through electrode of the third through hole 211, the through electrode of the first through hole 12g, and the through electrode of the sixth through hole 33 in this order. The metal film 28 is also connected to earth (ground connection, using a part of the external electrode terminal 32) via the through electrode of the third through hole 211, the through electrode of the first through hole 12g, and the sixth through hole 33 in this order.

[0040] In the quartz crystal unit 100, the various bonding patterns are preferably formed by stacking multiple layers on the quartz crystal plate, with a Ti (titanium) layer and an Au (gold) layer formed from the bottom layer onward by vapor deposition or sputtering. Furthermore, if the other wiring and electrodes formed on the quartz crystal unit 100 have the same configuration as the bonding patterns, the bonding patterns, wiring, and electrodes can be patterned simultaneously, which is preferable.

[0041] In the quartz crystal unit 100 configured as described above, the sealing portions (seal paths) 15, 16 that hermetically seal the vibrating portion 11 of the quartz crystal vibrating plate 10 are formed in an annular shape in a plan view. The seal path 15 is formed by diffusion bonding (Au-Au bonding) the above-mentioned diaphragm-side first bonding pattern 121 and the sealing member-side first bonding pattern 24. The outer edge of the seal path 15 is formed in a substantially rectangular shape, and the outer periphery of the seal path 15 is disposed in close proximity to the outer periphery of the package. Similarly, the seal path 16 is formed by diffusion bonding (Au-Au bonding) the above-mentioned diaphragm-side second bonding pattern 122 and the sealing member-side second bonding pattern 31. The outer edge of the seal path 16 is formed in a substantially rectangular shape, and the outer periphery of the seal path 16 is disposed in close proximity to the outer periphery of the package. The seal paths 15, 16 are not electrically connected to the electrical conduction paths between the first and second excitation electrodes 111, 112 and the external electrode terminals 32, 32. Specifically, the seal path 15 is connected to the seal path 16 via internal wiring 19, and the seal path 16 is further connected to earth (ground connection, using part of the external electrode terminal 32) via the penetrating electrode of the through hole 33c.

[0042] In the quartz crystal unit 100 configured as described above, the sealing portions (seal paths) 15, 16 that hermetically seal the vibrating portion 11 of the quartz crystal vibrating plate 10 are formed in an annular shape in a plan view. The seal path 15 is formed by diffusion bonding (Au-Au bonding) the above-mentioned diaphragm-side first bonding pattern 121 and the sealing member-side first bonding pattern 24. The outer edge of the seal path 15 is formed in a substantially rectangular shape, and the outer periphery of the seal path 15 is disposed in close proximity to the outer periphery of the package. Similarly, the seal path 16 is formed by diffusion bonding (Au-Au bonding) the above-mentioned diaphragm-side second bonding pattern 122 and the sealing member-side second bonding pattern 31. The outer edge of the seal path 16 is formed in a substantially rectangular shape, and the outer periphery of the seal path 16 is disposed in close proximity to the outer periphery of the package.

[0043] In the quartz crystal unit 100 in which the seal paths 15, 16 are formed by diffusion bonding in this manner, a gap of 1.00 μm or less exists between the first sealing member 20 and the quartz crystal plate 10, and a gap of 1.00 μm or less exists between the second sealing member 30 and the quartz crystal plate 10. In other words, the thickness of the seal path 15 between the first sealing member 20 and the quartz crystal plate 10 is 1.00 μm or less, and the thickness of the seal path 16 between the second sealing member 30 and the quartz crystal plate 10 is 1.00 μm or less (specifically, 0.15 μm to 1.00 μm in the Au-Au bonding of this embodiment). For comparison, a conventional metal paste sealing material using Sn has a thickness of 5 μm to 20 μm.

[0044] In this embodiment, the quartz crystal vibrating plate 10 has a pair of vibration holders 13a extending along a first imaginary line L1 in a first direction (X-axis direction) passing through the center point C1 of the vibrating portion 11 in a plan view, and a pair of outer frame holders 13b extending in a direction different from the first direction (Z'-axis direction) and connecting each vibration holder 13a to two locations on the inner peripheral wall of the outer frame 12. Each vibration holder 13a connects the outer peripheral wall of the vibrating portion 11 to the outer frame holder 13b, and the outer frame holder 13b connects the vibration holder 13a to the inner peripheral wall of the outer frame 12. The outer frame 12 has through-holes extending through the thickness or thin-walled portions that are located on the extension lines of the outer frame holders 13b. This point will be described with reference to FIG. 4.

[0045] As shown in Fig. 4, the vibrating unit 11 has a rectangular shape in a plan view, and the +X and -X direction sides of the vibrating unit 11 are provided with holding portions 13 each having a substantially T-shape in a plan view. The holding portions 13 are arranged symmetrically with respect to the first and second imaginary lines L1 and L2. Specifically, the holding portion 13 is integrally formed with a vibration holding portion 13a extending linearly from the outer peripheral wall of the vibrating unit 11 along the first imaginary line L1 and an outer frame holding portion 13b extending linearly parallel to the second imaginary line L2. The first imaginary line L1 is a line connecting the center point (center of gravity) C1 of the vibrating unit 11 in a plan view and the center of each outer frame holding portion 13b in the extension direction (Z'-axis direction).

[0046] The vibration retaining portion 13a and the outer frame retaining portion 13b are connected in directions perpendicular to each other. The vibration retaining portion 13a extends toward the outer frame retaining portion 13b along the long side direction of the inner peripheral wall of the outer frame portion 12 in a plan view, and the outer frame retaining portion 13b extends toward the inner peripheral wall of the outer frame portion 12 along the short side direction of the inner peripheral wall of the outer frame portion 12 in a plan view. One end of the vibration retaining portion 13a is connected to the center of the vibrating portion 11 in the Z'-axis direction, and the other end of the vibration retaining portion 13a is connected to the center of the outer frame retaining portion 13b in the Z'-axis direction. The outer frame retaining portion 13b is connected to four corner regions of the inner peripheral wall of the outer frame portion 12 in a plan view. One end of the outer frame holding portion 13b is connected to the inner wall of the outer frame portion 12 on the +Z' direction side, and the other end of the outer frame holding portion 13b is connected to the inner wall of the outer frame portion 12 on the -Z' direction side.

[0047] Both vibration retaining portion 13a and outer frame retaining portion 13b are formed linearly in a plan view. Vibration retaining portion 13a is formed to be wider and shorter in a plan view than outer frame retaining portion 13b. Specifically, the length of vibration retaining portion 13a along the X-axis direction is shorter than the length of outer frame retaining portion 13b along the Z'-axis direction. The width of vibration retaining portion 13a along the Z'-axis direction is wider than the width of outer frame retaining portion 13b along the X-axis direction.

[0048] The holding portion 13 configured as described above divides the cutout portion formed between the outer peripheral wall of the vibrating portion 11 and the inner peripheral wall of the outer frame portion 12 into multiple (four in this case) portions in plan view. Specifically, cutout portion 14a is the portion surrounded by the outer peripheral wall of the vibrating portion 11, the inner peripheral wall of the outer frame portion 12, and the vibration holding portion 13a and outer frame holding portion 13b of the holding portion 13, and is formed in a substantially U-shape in plan view. Cutout portion 14b is the portion surrounded by the inner peripheral wall of the outer frame portion 12 and the outer frame holding portion 13b of the holding portion 13, and is formed in a straight line extending along the Z'-axis direction in plan view.

[0049] 4, the first through holes 12g provided in the four corner regions of the outer frame portion 12 are located on the extension line of the outer frame holding portion 13b of the holding portion 13. In this embodiment, all four first through holes 12g are provided on the extension line of the outer frame holding portion 13b of the holding portion 13. The four first through holes 12g are provided in positions that are line-symmetrical with respect to the first imaginary line L1 and are also provided in positions that are line-symmetrical with respect to the second imaginary line L2. On the other hand, the second through holes 12h are not provided on the extension line of the outer frame holding portion 13b of the holding portion 13.

[0050] According to this embodiment, in the quartz crystal vibrating plate 10, a pair of vibration retainers 13a are connected to both ends of the vibrating portion 11 in the X-axis direction, and outer frame retainers 13b extending in the Z'-axis direction are connected to four locations of the outer frame portion 12. This suppresses the effects of external stress and reduces deflection in the thickness direction. Specifically, by forming the vibration retainers 13a along a first imaginary line L1 in a first direction (here, the longitudinal X-axis direction) passing through the center point C1 of the vibrating portion 11 in a planar view, it is possible to effectively suppress displacement of the vibrating portion 11 in the thickness direction with as few points as possible. By supporting the vibrating portion 11 with the vibration retainers 13a and the outer frame retainers 13b extending in different directions, it is possible to effectively suppress displacement of the vibrating portion 11 in the first direction and directions different from the first direction with as few points as possible. Because the vibrating portion 11 is supported by only two retaining parts, the vibration retainers 13a and the outer frame retainers 13b extending in different directions, it is possible to avoid unnecessary reduction in the effective area of ​​the vibrating portion 11. Furthermore, by forming the vibration retaining portions 13a along the first imaginary line L1 connecting the center point C1 of the vibrating portion 11 in a plan view and the center of each outer frame retaining portion 13b in the extension direction (Z'-axis direction), stress transmitted from the outer frame retaining portions 13b to the vibrating portion 11 is uniform, preventing unbalanced stress transmission to the vibrating portion 11. Therefore, according to this embodiment, by indirectly connecting the vibrating portion 11 to the outer frame portion 12 via the retaining portions 13 and using a structure in which the vibrating portion 11 is held at four points in the four corner regions of the outer frame portion 12, the acceleration sensitivity evaluation of the quartz crystal vibrating plate 10 is satisfied without hindering miniaturization. Moreover, a holding structure for the quartz crystal vibrating plate 10 can be provided that ensures an effective planar view area for the vibrating portion 11 and is resistant to the effects of external stress and vibration leakage, resulting in an excellent overall balance.

[0051] Furthermore, the first through-hole 12g is located on the extension line of the outer frame holding portion 13b of the holding portion 13. This makes it possible to inhibit the transmission of vibration at the connection portion between the outer frame holding portion 13b of the holding portion 13 and the outer frame portion 12 at the portion of the first through-hole 12g, thereby reducing vibration leakage from the outer frame holding portion 13b to the outer frame portion 12. Moreover, the portion of the first through-hole 12g can relieve stress due to external impact, and also suppress the transmission of external stress from the outer frame portion 12 to the outer frame holding portion 13b.

[0052] Furthermore, if electrical wiring is formed on the inner wall of the outer frame portion 12, there is a possibility that it may come into contact with the outside and become disconnected. However, as described above, a through electrode that connects the front and back main surfaces of the outer frame portion 12 is formed on the inner wall surface of the first through hole 12g, and such disconnection can be prevented by using the through electrode of the first through hole 12g as electrical wiring.

[0053] In this embodiment, the relationship of thickness of outer frame portion 12 > thickness of outer peripheral portion 11b of vibrating portion 11 > thickness of retaining portion 13 is satisfied, and one end of retaining portion 13 is connected to a central portion in the thickness direction of outer peripheral portion 11b of vibrating portion 11, and the other end of retaining portion 13 is connected to a central portion in the thickness direction of the inner peripheral wall of outer frame portion 12. As a result, retaining portion 13 is sandwiched between outer frame portion 12 and outer peripheral portion 11b of vibrating portion 11, which are thicker than retaining portion 13, thereby improving the stress relaxation performance of retaining portion 13 in the thickness direction (Y-axis direction). Furthermore, because the vibrating portion 11, retaining portion 13, and outer frame portion 12 are symmetrical in the thickness direction (up-down direction), a structure can be achieved in which even if vibrating portion 11 bends in the thickness direction, the bending is less likely to be uneven.

[0054] The vibrating portion 11 has an inverted mesa shape, with the central portion 11a being thinner than the outer peripheral portion 11b. The relationship of thickness of outer frame portion 12 > thickness of outer peripheral portion 11b of vibrating portion 11 > thickness of holding portion 13 ≥ thickness of central portion 11a of vibrating portion 11 is satisfied. Thus, by thinning the central portion 11a of vibrating portion 11, higher frequencies can be accommodated, and the outer peripheral portion 11b of vibrating portion 11 can improve the strength of the vibrating portion 11. By alternately arranging relatively thin portions (central portion 11a and holding portion 13) that can accommodate higher frequencies and relatively thick portions (outer peripheral portion 11b and outer frame portion 12) that can accommodate lower frequencies, leakage of the main vibration of the vibrating portion 11 can be suppressed.

[0055] In this embodiment, the outer frame holding portions 13b are shaped to be line-symmetrical with respect to a first imaginary line L1 passing through the center point C1 of the vibrating portion 11 in a planar view, and are shaped to be line-symmetrical with respect to a second imaginary line L2 passing through the center point C1 of the vibrating portion 11 in a planar view and intersecting (orthogonal to) the first imaginary line L1. This makes it possible to uniformize the stress transmitted from the outer frame portion 12 to the vibration holding portions 13a and suppress unbalanced transmission of stress to the vibration holding portions 13a. Furthermore, by forming the vibration holding portions 13a along the first imaginary line L1 connecting the center point C1 of the vibrating portion 11 in a planar view and the center of the extension direction (Z'-axis direction) of each outer frame holding portion 13b, it is possible to uniformize the stress transmitted from the outer frame holding portions 13b to the vibrating portion 11 and suppress unbalanced transmission of stress to the vibrating portion 11.

[0056] In this embodiment, the inner wall of the outer frame portion 12 and the outer wall of the vibrating portion 11 are both rectangular in plan view, and are arranged in a direction perpendicular to the long side direction of the quartz crystal vibration plate 10 in plan view (here, the Z'-axis direction) and the long side direction of the inner wall of the outer frame portion 12 in plan view (here, the X-axis direction), and each vibration retaining portion 13a extends toward the outer frame retaining portion 13b along the long side direction of the inner wall of the outer frame portion 12 in plan view, connecting the outer wall of the vibrating portion 11 and the outer frame retaining portion 13b, and the outer frame retaining portion 13b extends toward the inner wall of the outer frame portion 12 along the short side direction of the inner wall of the outer frame portion 12 in plan view (here, the Z'-axis direction), connecting the inner wall of the outer frame portion 12 and the vibration retaining portion 13a in the four corner areas of the inner wall of the outer frame portion 12 in plan view. This allows for the formation of wide regions (regions at both ends in the Z'-axis direction) on both sides of the inner peripheral wall of the outer frame 12 in the direction of the long side in plan view, ensuring an effective area for wiring and bonding, without hindering the miniaturization of the quartz crystal vibrating plate 10. On the other hand, narrow regions (regions at both ends in the X-axis direction) are formed on both sides of the inner peripheral wall of the outer frame 12 in the direction of the short side in plan view, ensuring an effective area for the vibrating part 11 by the amount of these narrow regions.

[0057] Furthermore, the vibration holding portion 13a, which has fewer connection points (joint points) and a smaller occupied area in plan view, is arranged along the long side of the inner peripheral wall of the outer frame portion 12 in plan view, thereby ensuring the effective area of ​​the vibrating portion 11 and contributing to the miniaturization of the quartz crystal vibrating plate 10. Furthermore, the outer frame holding portion 13b, which has more connection points and a larger occupied area in plan view, is arranged along the short side of the inner peripheral wall of the outer frame portion 12, thereby shortening the length of the outer frame holding portion 13b and ensuring the effective area of ​​the vibrating portion 11, contributing to the miniaturization of the quartz crystal vibrating plate 10. Additionally, the outer frame holding portion 13b can be connected to the wide region of the outer frame portion 12, which is advantageous for ensuring strength against external impacts. Furthermore, the outer frame holding portion 13b is connected to the four corner regions of the inner peripheral wall of the outer frame portion 12 in plan view, which easily alleviates bending and stress of the outer frame portion 12 due to external impacts, which is advantageous for stress relief.

[0058] In this embodiment, each vibration retaining portion 13a and each outer frame retaining portion 13b is formed linearly in a plan view, and each vibration retaining portion 13a and each outer frame retaining portion 13b are connected in directions perpendicular to each other, so that by making both vibration retaining portions 13a and outer frame retaining portions 13b linear, the areas of vibration retaining portions 13a and outer frame retaining portions 13b are not unnecessarily enlarged, and it is possible to ensure the effective area of ​​vibrating portion 11. Furthermore, it is possible to achieve well-balanced stress relaxation corresponding to the extension directions of vibration retaining portions 13a and outer frame retaining portions 13b.

[0059] Furthermore, one end of each vibration retaining portion 13a is connected to the center of the opposing short sides of the vibrating portion 11, thereby effectively suppressing deflection of the vibrating portion 11 with a small number of connection points. The other end of each vibration retaining portion 13a is connected to the center of the outer frame retaining portion 13b, thereby easily maintaining the balance of the retaining portion 13 and effectively suppressing deflection of the vibrating portion 11.

[0060] Furthermore, since each vibration retaining portion 13a is wider and shorter in length in a planar view than the outer frame retaining portion 13b, by making the outer frame retaining portion 13b, which has more connection points, longer and thinner, and the vibration retaining portion 13a, which has fewer connection points, shorter and thicker, the strength of the retaining portion 13 can be ensured without increasing the occupied area in a planar view.

[0061] In this embodiment, first and second escape wirings 113 and 114 are formed to extend from the first excitation electrode 111 and the second excitation electrode 112 of the vibrating portion 11 to the outer frame portion 12 via the holding portion 13, and the vibration holding portion 13a of the holding portion 13 is connected to an end portion in the X-axis direction of the outer peripheral portion 11b of the vibrating portion 11. In an AT-cut quartz crystal vibrating plate, a step (step portion) 11c is formed between the central portion 11a and the outer peripheral portion 11b of the vibrating portion 11, and a step portion is also formed between the outer peripheral portion 11b of the vibrating portion 11 and the vibration holding portion 13a of the holding portion 13. However, by extending the first and second escape wirings 113 and 114 in the X-axis direction, where the slope of the step portion is gentler than in the Z'-axis direction, breaks in the first and second escape wirings 113 and 114 can be prevented. Furthermore, the vibration holding portion 13a is a relatively narrow area, making it more difficult to form the necessary wiring compared to the outer frame holding portion 13b, but by extending the first outgoing wiring 113 and the second outgoing wiring 114 along the X-axis direction, it is possible to prevent breakage of the first outgoing wiring 113 and the second outgoing wiring 114.

[0062] The quartz crystal unit 100 including the quartz crystal plate 10 described above also provides the same effects as those of the quartz crystal plate 10 described above. That is, it is possible to suppress the effects of external stress, etc., and to suppress bending of the quartz crystal plate 10 in the thickness direction. Furthermore, because the internal wiring 17 is not exposed on the outer surface of the package of the quartz crystal unit 100, the internal wiring 17 will not be broken or scraped off due to contact during assembly or transportation.

[0063] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments, but should be defined by the scope of the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included.

[0064] The number of first through holes 12g described above is an example, and for example, three or fewer first through holes 12g may be formed in the outer frame portion 12. In the above embodiment, all four first through holes 12g are located on the extension line of the outer frame holding portion 13b, but this is not limiting, and at least one first through hole 12g may be located on the extension line of the outer frame holding portion 13b.

[0065] The shapes and numbers of the vibration retaining portion 13a and the outer frame retaining portion 13b described above are merely examples and can be modified in various ways. For example, the vibration retaining portion 13a may be trapezoidal, with the width on the vibration portion 11 side narrower than the width on the outer frame retaining portion 13b side. Furthermore, the outer frame retaining portion 13b may be V-shaped, bent at a predetermined angle, or may be arc-shaped or elliptical-shaped. In this case, the end of the outer frame retaining portion 13b is connected to a corner of the inner peripheral wall of the outer frame portion 12, forming the retaining portion 13 in a substantially Y-shape. It is preferable that the number of connection points (joint points) between the vibration retaining portion 13a and the outer frame retaining portion 13b be an even number, and that the number of connection points on the outer frame retaining portion 13b be a multiple of the number of connection points on the vibration retaining portion 13a.

[0066] In the above embodiment, the thickness of the vibration holding portion 13 a of the holding portion 13 is the same as the thickness of the outer frame holding portion 13 b, but the thickness of the vibration holding portion 13 a may be different from the thickness of the outer frame holding portion 13 b. Also, in the above embodiment, the thickness T3 of the holding portion 13 is thicker than the thickness T1 of the central portion 11 a of the vibrating portion 11, but the thickness T3 of the holding portion 13 may be the same as the thickness T1 of the central portion 11 a of the vibrating portion 11.

[0067] In the above embodiment, the first through-holes 12g are provided on the extension lines of the outer frame holding portions 13b of the outer frame portion 12. However, as shown in FIGS. 9 and 10, thin-walled portions 12m, 12n having a smaller thickness in the thickness direction may be formed on the extension lines of the outer frame holding portions 13b of the outer frame portion 12. Specifically, as shown in FIG. 9, on the first main surface 101 side of the quartz crystal vibrating plate 10, thin-walled portions 12m are continuously formed at both ends of the outer frame holding portions 13b in the Z'-axis direction. The thin-walled portions 12m are formed in a substantially triangular shape in a plan view, and connection bonding patterns 12a, 12b are formed on the surfaces of the thin-walled portions 12m. The thin-walled portions 12m are provided at four locations on the outer frame portion 12 where the outer frame holding portions 13b are connected to the inner peripheral wall of the outer frame portion 12. The four thin-walled portions 12m have the same shape. The four thin-walled portions 12m are provided at positions that are line-symmetrical with respect to the first virtual straight line L1 (see Figure 4) described above, and are also provided at positions that are line-symmetrical with respect to the second virtual straight line L2 (see Figure 4) described above.

[0068] As shown in FIG. 10 , on the second principal surface 102 side of the quartz crystal plate 10, thin-walled portions 12n are continuously formed at both ends of the outer frame holding portion 13b in the Z′-axis direction. Each thin-walled portion 12n is formed in a substantially triangular shape in a plan view, and connection bonding patterns 12e and 12f are formed on the surface of each thin-walled portion 12n. The thin-walled portions 12n are provided at four locations on the outer frame portion 12 where the outer frame holding portion 13b is connected to the inner peripheral wall of the outer frame portion 12. The four thin-walled portions 12n have the same shape. The four thin-walled portions 12n are positioned line-symmetrically with respect to the first virtual straight line L1 (see FIG. 4 ) and the second virtual straight line L2 (see FIG. 4 ).

[0069] By providing the thin-walled portions 12m, 12n as described above in the outer frame portion 12, the thin-walled portions 12m, 12n can inhibit the transmission of vibration at the connection portion between the outer frame holding portion 13b of the holding portion 13 and the outer frame portion 12, thereby reducing vibration leakage from the outer frame holding portion 13b to the outer frame portion 12. Furthermore, the thin-walled portions 12m, 12n can absorb stress due to external impact, thereby suppressing the transmission of external stress from the outer frame portion 12 to the outer frame holding portion 13b. Furthermore, the thin-walled portions 12m, 12n have wiring electrodes formed on the thin-walled portions 12m, 12n that extend through steps formed in the outer frame portion 12. Therefore, the thin-walled portions 12m, 12n are disposed between the outer frame holding portion 13b and the outer frame portion 12, and thus, by changing the shape of the steps (changing the axial direction of the steps), breakage of the wiring electrodes can be suppressed.

[0070] The shapes and numbers of the thin-walled portions 12m, 12n described above are merely examples, and for example, three or fewer thin-walled portions 12m, 12n may be formed on the outer frame portion 12. Furthermore, the shapes of the thin-walled portions 12m, 12n may be, for example, substantially rectangular or semicircular. In the example shown in FIGS. 9 and 10 , all four thin-walled portions 12m, 12n are located on the extension line of the outer frame holding portion 13b. However, this is not limited to this. At least one thin-walled portion 12m, 12n may be located on the extension line of the outer frame holding portion 13b. In the example shown in FIGS. 9 and 10 , the thin-walled portions 12m, 12n are provided on both the first main surface 101 side and the second main surface 102 side of the outer frame portion 12. However, a thin-walled portion may be provided on only one of the first main surface 101 side and the second main surface 102 side of the outer frame portion 12. 9 and 10, there is a step between the thin-walled portions 12m, 12n and the outer frame holding portion 13b, but the thin-walled portions 12m, 12n and the outer frame holding portion 13b may be flush with each other to eliminate the step. Also, in the example of Fig. 9 and 10, the outer frame portion 12 is provided with the thin-walled portions 12m, 12n as well as the first through-hole 12g, but the outer frame portion 12 may be provided with only the thin-walled portions 12m, 12n without the first through-hole 12g, or, as in the above embodiment, the outer frame portion 12 may be provided with only the first through-hole 12g without the thin-walled portions 12m, 12n (see Figs. 4 and 5).

[0071] In the above-described embodiment, the long side direction of the quartz crystal vibrating plate 10 and the long side direction of the vibrating portion 11 in a plan view may be aligned. For example, as shown in FIGS. 11 and 12 , the quartz crystal vibrating plate 10 and the vibrating portion 11 are formed in a rectangular shape in a plan view, and the long side direction of the quartz crystal vibrating plate 10 and the long side direction of the vibrating portion 11 are both parallel to the X-axis direction. In the examples of FIGS. 11 and 12 , the X-axis direction and the Z′-axis direction of the quartz crystal vibrating plate 10 are different by 90 degrees from those in the above-described embodiment, and the X-axis direction and the Z′-axis direction are reversed. However, the rest of the configuration of the quartz crystal vibrating plate 10 is the same as in the above-described embodiment. For example, in the examples of FIGS. 11 and 12 , the vibration holding portion 13a of the holding portion 13 extends along the Z′-axis direction, and the outer frame holding portion 13b extends along the X-axis direction. In addition, wide regions (regions at both ends in the X-axis direction) are formed on both sides of the inner wall of the outer frame portion 12 in the long side direction when viewed in a plane, and narrow regions (regions at both ends in the Z'-axis direction) are formed on both sides of the inner wall of the outer frame portion 12 in the short side direction when viewed in a plane.

[0072] By arranging the long sides of the quartz crystal vibrating plate 10 and the vibrating portion 11 parallel to the X-axis direction, the planar area of ​​the cutout 14a formed between the vibrating portion 11, the outer frame 12, and the holding portion 13 can be minimized, thereby maximizing the planar area of ​​the vibrating portion 11 and ensuring as wide a vibration region as possible for the vibrating portion 11. Furthermore, the internal wiring 17 is provided on the inner wall of the outer frame 12 that is aligned along the Z'-axis direction and is on the +X-direction side, while the internal wiring 18 is provided on the inner wall of the outer frame 12 that is aligned along the Z'-axis direction and is on the -X-direction side. Thus, the internal wiring 17 and 18 are provided on the X-axis end face of the cutout 14a. Here, when the cutout portion 14a is formed by wet etching, due to the anisotropy of the AT-cut quartz plate, the X-axis end face of the cutout portion 14a has a shape in which multiple, continuously inclined surfaces are formed that are more gentle than the Z'-axis end face. Therefore, by forming the internal wiring 17, 18 on such an X-axis end face, the film thickness of the internal wiring 17, 18 can be ensured and breakage of the internal wiring 17, 18 can be suppressed.

[0073] Furthermore, since the vibration support portion 13a extends in a direction (Z'-axis direction) perpendicular to the vibration direction (X-axis direction) of the thickness-shear vibration of the vibrating portion 11, it is possible to reduce the frequency response sensitivity to external vibrations and suppress frequency fluctuations. Here, if the vibration support portion 13a extends in the vibration direction (X-axis direction) of the thickness-shear vibration of the vibrating portion 11, the vibrating portion 11 may be displaced in response to external vibrations, which may cause capacitance fluctuations and increase frequency fluctuations, but this embodiment can solve such problems.

[0074] In the above embodiment, the width of the vibration retaining portion 13a of the retaining portion 13 (the width in the direction perpendicular to the extension direction of the vibration retaining portion 13a) may be greater than the distance (gap) between the vibrating portion 11 of the cutout portion 14a and the outer frame retaining portion 13b. For example, in the example of FIG. 11 , the width W1 in the X-axis direction of the vibration retaining portion 13a connected to the +Z' side of the vibrating portion 11 is greater than the distance D1 between the vibrating portion 11 of the cutout portion 14a and the outer frame retaining portion 13b (W1 > D1). Furthermore, the width W2 in the X-axis direction of the vibration retaining portion 13a connected to the -Z' side of the vibrating portion 11 is greater than the distance D2 between the vibrating portion 11 of the cutout portion 14a and the outer frame retaining portion 13b (W2 > D2). The width W1 and width W2 are the same (W1 = W2). The distances D1 and D2 are the lengths of each vibration retaining portion 13a in the Z'-axis direction (the lengths of the vibration retaining portions 13a in the extension direction), and are the same as each other (D1 = D2). This relationship allows the widths W1 and W2 of the vibration retaining portions 13a at the portions where the retaining portions 13 are connected to the vibrating portion 11 to be made as large as possible, thereby improving the strength of the retaining portions 13.

[0075] In the above embodiment, an AT-cut quartz crystal diaphragm is used as the piezoelectric diaphragm, but other piezoelectric diaphragms that perform thickness-shear vibration may also be used.

[0076] In the above embodiment, the first sealing member 20 and the second sealing member 30 are formed from a quartz plate, but this is not limited to this, and the first sealing member 20 and the second sealing member 30 may be formed from, for example, glass or resin.

[0077] In the above embodiment, the number of external electrode terminals 32 on the second main surface 302 of the second sealing member 30 is four, but this is not limited thereto, and the number of external electrode terminals 32 may be, for example, two, six, or eight. Furthermore, while the present invention has been described as being applied to the quartz crystal resonator 100, this is not limited thereto, and the present invention may also be applied to, for example, a piezoelectric oscillator such as a quartz crystal oscillator. In the case of a piezoelectric oscillator, as described above, by routing the first escape wiring 113 and the second escape wiring 114 on the piezoelectric diaphragm along the shortest possible path (see FIG. 8 ), parasitic capacitance can be reduced, thereby ensuring a wide variable frequency range of the piezoelectric oscillator and improving the performance of the piezoelectric oscillator, which is particularly effective in a VCXO (voltage-controlled piezoelectric oscillator).

[0078] In the above embodiment, the electrical connection path from a pair of excitation electrodes (first excitation electrode 111, second excitation electrode 112) formed on the quartz crystal vibration plate 10 to the external electrode terminal 32 on the second main surface 302 of the second sealing member 30 is formed by a through hole penetrating the second sealing member 30 and a through electrode within the through hole. However, this is not limited to this, and the present invention may also be applied to a configuration in which a castellation is provided on the outer end surface of the second sealing member 30 and electrical connection is made by an outer end electrode within the castellation.

[0079] This application claims priority from Japanese Patent Application No. 2024-57035, filed on March 29, 2024, the entire contents of which are incorporated herein by reference.

[0080] DESCRIPTION OF SYMBOLS 10 Quartz crystal vibration plate (piezoelectric vibration plate) 11 Vibration portion 12 Outer frame portion 12g First through hole (penetrating hole) 12m, 12n Thin portion 13 Holding portion 13a Vibration holding portion 13b Outer frame holding portion 14a, 14b Cutout portion 20 First sealing member (upper sealing plate) 30 Second sealing member (lower sealing plate) 100 Quartz crystal vibrator (piezoelectric vibration device) 111 First excitation electrode 112 Second excitation electrode L1 First imaginary line L2 Second imaginary line

Claims

1. A piezoelectric diaphragm that vibrates in a thickness-shear manner, comprising: a vibrating section having excitation electrodes formed on its main surface; an outer frame section that surrounds the vibrating section; a retaining section that connects the vibrating section to the outer frame section; and a cutout section that is formed by cutting out in the thickness direction between the vibrating section and the outer frame section, wherein the retaining section has a pair of vibration retaining sections that are aligned along a first imaginary line in a first direction that passes through the center point of the vibrating section in a plan view; and a pair of outer frame retaining sections that extend in a direction different from the first direction and connect each vibration retaining section to two points on the outer frame section, wherein each vibration retaining section connects the vibrating section to the outer frame retaining section, and the outer frame retaining section connects the vibration retaining section to the outer frame section, and the outer frame section has at least one of a through hole that penetrates in the thickness direction and a thin section that is thin in the thickness direction formed in the outer frame section, and at least one of the through hole and the thin section is located on the extension line of the outer frame retaining section.

2. A piezoelectric diaphragm according to claim 1, characterized in that the outer frame holding portion is formed in line symmetry with respect to the first imaginary line and in line symmetry with respect to a second imaginary line along a second direction perpendicular to the first imaginary line.

3. A piezoelectric diaphragm according to claim 1, characterized in that when the through-hole is formed in the outer frame portion, a through-electrode is formed on the inner wall surface of the through-hole, providing electrical continuity between the front and rear main surfaces of the outer frame portion.

4. A piezoelectric diaphragm as described in claim 1, characterized in that when the thin-walled portion is formed in the outer frame portion, a wiring electrode is formed in the thin-walled portion, passing through a step formed in the outer frame portion.

5. The piezoelectric diaphragm according to claim 1, characterized in that the piezoelectric diaphragm is an AT-cut quartz crystal diaphragm.

6. A piezoelectric vibration device comprising a piezoelectric vibration plate according to any one of claims 1 to 5, characterized in that an upper sealing plate covering the upper surface of the piezoelectric vibration plate and a lower sealing plate covering the lower surface of the piezoelectric vibration plate are bonded to the piezoelectric vibration plate.

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