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 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), each outer frame holding part (13b) connects the vibration holding part (13a) and the outer frame part (12), and a relationship in which the thickness (T4) of the outer frame part (12) is greater than the thickness (T2) of an outer peripheral part (11b) of the vibration part (11), which is greater than the thickness (T3) of the holding part (13) is satisfied. One end of the holding part (13) is connected to a central section in the thickness direction of an outer peripheral part (11b) of the vibration part (11), and the other end of the holding part (13) is connected to a central section in the thickness direction of the outer frame part (12).

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 the means for solving the above-mentioned problems as follows. In other words, the present invention is a piezoelectric diaphragm that vibrates in a thickness-shear manner, and is configured to include a vibrating portion having an excitation electrode formed on its main surface, 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 in the thickness direction between the vibrating portion and the outer frame portion, wherein the retaining portion has a pair of vibration retaining portions along a first imaginary line in a first direction passing through the center point of the vibrating portion in a planar view, and a pair of outer frame retaining portions that extend in a direction different from the first direction and connect each vibration retaining portion to two points on the outer frame portion, each vibration retaining portion connects the vibrating portion and the outer frame retaining portion, and the outer frame retaining portion connects the vibration retaining portion and the outer frame portion, satisfying the relationship: thickness of the outer frame portion > thickness of the outer peripheral portion of the vibrating portion > thickness of the retaining portion, and one end of the retaining portion is connected to the central portion of the outer peripheral portion of the vibrating portion in the thickness direction, and the other end of the retaining portion is connected to the central portion of the outer frame portion in the thickness direction. 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 that surrounds an outer peripheral wall of the vibrating portion, a holding portion that connects the outer peripheral wall of the vibrating portion and the inner peripheral wall of the outer frame portion, and a cutout portion that is 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 that are 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 that extend in a direction different from the first direction and that connect each vibration holding portion to the The vibration retaining portion has a pair of outer frame retaining portions connected to two points on the inner peripheral wall of the outer frame portion, and each vibration retaining portion connects the outer peripheral wall of the vibration portion to the outer frame retaining portion, and the outer frame retaining portion connects the vibration retaining portion to the inner peripheral wall of the outer frame portion, satisfying the relationship: thickness of the outer frame portion > thickness of the outer peripheral portion of the vibration portion > thickness of the retaining portion, and one end of the retaining portion is connected to the central portion in the thickness direction of the outer peripheral portion of the vibration portion, and the other end of the retaining portion is connected to the central portion in the thickness direction of the inner peripheral wall of the outer frame portion.

[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 support portion along a first virtual line connecting the center point of the vibrating portion in a plan view and the center of the extension direction of each outer frame support portion, the stress transmitted from the outer frame support portion to the vibrating portion can be made uniform, thereby preventing unbalanced stress transmission to the vibrating portion. Furthermore, since the support portion is sandwiched between the thicker outer frame portion and the outer periphery of the vibrating portion, the stress relaxation performance of the support portion in the thickness direction can be improved. Furthermore, since the vibrating portion, support portion, and outer frame portion are symmetrical in the thickness direction, a structure can be achieved in which even if the vibrating portion bends in the thickness direction, the bending is less likely to be uneven.

[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, the vibration portion is preferably formed so that its inner central portion is thinner than its outer peripheral portion, and the relationship of thickness of the outer frame portion > thickness of the outer peripheral portion of the vibration portion > thickness of the holding portion ≥ thickness of the central portion of the vibration portion is satisfied. With this configuration, the thickness of the central portion of the vibration portion can be reduced to accommodate higher frequencies, and the strength of the vibration portion can be improved by reducing the thickness of the outer peripheral portion of the vibration portion. By alternately arranging relatively thin portions (the central portion of the vibration portion, the holding portion) that can accommodate higher frequencies and relatively thick portions (the outer frame portion of the vibration portion, the outer frame portion) that can accommodate lower frequencies, leakage of the main vibration of the vibration portion can be suppressed. Furthermore, because the vibration portion, the holding portion, and the outer frame portion are symmetrical in the thickness direction, a structure can be achieved in which deflection in the thickness direction is less likely to be biased.

[0012] In the piezoelectric diaphragm having the above configuration, the piezoelectric diaphragm is preferably an AT-cut quartz crystal diaphragm. In this case, it is preferable that an extraction wiring is formed that extends from the excitation electrode of the vibrating portion to the outer frame portion via the holding portion, and the vibration holding portion of the holding portion is connected to the end of the outer periphery of the vibrating portion in the X-axis direction. In an AT-cut quartz crystal diaphragm, a step is formed between the center and outer periphery of the vibrating portion, and a step is also formed between the outer periphery of the vibrating portion and the vibration holding portion of the holding portion. However, by extending the extraction wiring in the X-axis direction, where the slope of the step is gentler than in the Z'-axis direction, breakage of the extraction wiring can be prevented.

[0013] 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.

[0014] 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.

[0015] 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 the 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 the crystal unit plate according to this embodiment. FIG. 5 is a schematic plan view of the second main surface side of the crystal unit plate according to this embodiment. FIG. 6 is a schematic plan view of the first main surface side of the 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 cross-sectional view taken along line X1-X1 of FIG. 4. FIG. 9 is a view of a crystal unit plate according to another embodiment 1, equivalent to FIG. 4. FIG. 10 is a view of a crystal unit plate according to another embodiment 2, equivalent to FIG. 4. FIG. 11 is a view of a crystal unit plate according to another embodiment 2, equivalent to FIG. 5. FIG. 12 is a view of a crystal unit plate according to another embodiment 3, equivalent to FIG. 4. FIG. 13 is a view of a crystal unit plate according to another embodiment 3, equivalent to FIG. 5.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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. In this embodiment, the outer frame portion 12 of the quartz crystal vibrating plate 10 is configured without through-holes or castellations. The vibrating portion 11 is configured such that the outer peripheral portion 11b, where the first excitation electrode 111 and the second excitation electrode 112 are not formed, is thicker than the central portion 11a, where the first excitation electrode 111 and the second excitation electrode 112 are formed, and annular steps 11c are formed on both main surfaces of the vibrating portion 11. One holding portion 13 is provided on each of the +X direction side and the −X direction side of the vibrating portion 11. The holding portion 13 is configured by a vibration holding portion 13a on the vibrating portion 11 side and an outer frame holding portion 13b on the outer frame portion 12 side. Details of the holding portion 13 will be described later.

[0022] The first excitation electrode 111 is provided on the first main surface 101 side of the vibrating section 11, and the second excitation electrode 112 is provided on the second main surface 102 side of the vibrating section 11. 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 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 section 12 via a holding section 13 provided on the +X direction side of the vibrating section 11. The outer frame section 12 is formed thicker than the holding section 13, and a step is formed between the outer frame section 12 and the holding section 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 section 12. The connection junction pattern 12b is also connected to a connection junction pattern 12f formed on the second main surface 102 side of the outer frame portion 12 via internal wiring 17 formed on the inner peripheral wall of the outer frame portion 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.

[0023] The second escape wiring 114 is extracted from the second excitation electrode 112 toward the −X direction and connected to the connection junction pattern 12e formed on the second main surface 102 of the outer frame portion 12 via the holding portion 13 provided on the −X direction side of the vibrating portion 11. As described above, a step is formed between the outer frame portion 12 and the holding portion 13, and the second escape wiring 114 is connected to the connection junction pattern 12e via the internal wiring 18 formed on the inner circumferential wall of 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 on the −Z′ direction side. In this embodiment, the first escape wiring 113 and the second escape wiring 114 are extracted in different directions, so that the escape wirings in the vibrating portion 11 are not arranged opposite each other across the vibrating portion 11. This configuration eliminates unnecessary excitation by the escape wiring in the vibrating portion 11 and improves the stability of the characteristics.

[0024] 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 is on the inner circumferential wall on the -X direction side, and is perpendicular to the inner circumferential wall on which the above-mentioned internal wirings 17 and 18 are provided. Note that a connection bonding pattern 12a is formed on the first main surface 101 side of the outer frame portion 12.

[0025] As shown in FIGS. 2 and 3 , the first sealing member 20 is a rectangular parallelepiped substrate formed from a single AT-cut quartz crystal plate. The second main surface 202 (the surface bonded to the quartz crystal vibrating plate 10) of the first sealing member 20 is formed as a flat, smooth surface (mirror-finished). Although the first sealing member 20 does not have a vibrating portion, using an AT-cut quartz crystal plate like the quartz crystal vibrating plate 10 allows the quartz crystal vibrating plate 10 and the first sealing member 20 to have the same thermal expansion coefficient, thereby suppressing thermal deformation of the quartz crystal unit 100. Furthermore, the X-, Y-, and Z′-axes of the first sealing member 20 are also aligned with those of the quartz crystal vibrating plate 10. In this embodiment, the first sealing member 20 does not have through-holes or castellations, significantly shortening the manufacturing process of the first sealing member 20. Furthermore, eliminating a path for moisture to penetrate from the first main surface 201 of the first sealing member 20 into the internal space of the package improves corrosion resistance.

[0026] 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. The outer peripheral edge of the sealing member-side first bonding pattern 24 is provided close to the outer peripheral edge of the second main surface 202 of the first sealing member 20. In addition, connection bonding patterns 22a and 22b are formed on the second main surface 202 of the first sealing member 20 for bonding to the connection bonding patterns 12a and 12b formed on the first main surface 101 of the outer frame portion 12 of the quartz-crystal vibration plate 10.

[0027] 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 (the surface that bonds to the quartz crystal plate 10) of this second sealing member 30 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.

[0028] 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 an annular shape in a plan view. The outer peripheral edge of the sealing member-side second bonding pattern 31 is provided close to the outer peripheral edge of the first main surface 301 of the second sealing member 30. In addition, connection bonding patterns 34a and 34b are formed on the first main surface 301 of the second sealing member 30 for bonding to the connection bonding patterns 12e and 12f formed on the second main surface 102 of the outer frame portion 12 of the quartz-crystal vibration plate 10.

[0029] 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) for electrically connecting to an external circuit board provided outside the quartz crystal vibrating device 100. The external electrode terminals 32 are formed in a substantially rectangular 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.

[0030] As shown in Figures 6 and 7, the second sealing member 30 has three through holes 33a, 33b, and 33c formed therein, penetrating between the first main surface 301 and the second main surface 302. The through holes 33a, 33b, and 33c are provided in the four corner regions (corner portions) of the second sealing member 30. In the through holes 33a, 33b, and 33c, through electrodes are formed along the inner wall surfaces of the through holes 33a, 33b, and 33c, respectively, to establish electrical continuity between the electrodes formed on the first main surface 301 and the second main surface 302. The through electrodes formed on the inner wall surfaces of the through holes 33a, 33b, and 33c establish electrical continuity between the electrodes (connection bonding patterns) formed on the first main surface 301 and the external electrode terminals 32 formed on the second main surface 302. The central portion of each of the through holes 33 a , 33 b , and 33 c is a hollow through portion that penetrates between the first main surface 301 and the second main surface 302 .

[0031] 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.

[0032] 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 achieved between the first excitation electrode 111, the second excitation electrode 112, and the external electrode terminals 32, 32 in the quartz crystal resonator 100. Specifically, the first excitation electrode 111 is connected to the external electrode terminal 32 via the first extension wiring 113, the internal wiring 17, the connection bonding pattern 12f, the connection bonding pattern 34b, and the through-hole 33b through the through-hole electrode. The second excitation electrode 112 is connected to the external electrode terminal 32 via the second extension wiring 114, the internal wiring 18, the connection bonding pattern 12e, the connection bonding pattern 34a, and the through-hole 33a through the through-hole electrode.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] In this embodiment, in the quartz crystal vibrating plate 10 having the above-described configuration, the holding portion 13 includes a pair of vibration holding portions 13a along a first virtual straight line L1 in a first direction (X-axis direction) passing through a center point C1 in a plan view of the vibrating portion 11, and a pair of outer frame holding portions 13b extending in a direction (Z'-axis direction) different from the first direction and connecting each vibration holding portion 13a to two locations on the inner peripheral wall of the outer frame portion 12. Each vibration holding portion 13a is connected to the vibrating portion 11. The outer frame holding portion 13b connects the outer peripheral wall of the vibrating portion 11 to the outer frame holding portion 13b, and the outer frame holding portion 13b connects the vibration holding portion 13a to the inner peripheral wall of the outer frame portion 12. The relationship of thickness T4 of the outer frame portion 12 > thickness T2 of the outer peripheral portion 11b of the vibrating portion 11 > thickness T3 of the holding portion 13 is satisfied. One end of the holding portion 13 is connected to a central portion in the thickness direction of the outer peripheral portion 11b of the vibrating portion 11, and the other end of the holding portion 13 is connected to a central portion in the thickness direction of the inner peripheral wall of the outer frame portion 12. This point will be described with reference to FIGS. 4 and 8. Note that FIG. 8 does not show the first excitation electrode 111, the second excitation electrode 112, the first escape routing 113, the second escape routing 114, etc., which are formed on the first main surface 101 and the second main surface 102 of the quartz crystal vibrating plate 10.

[0037] 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).

[0038] 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.

[0039] 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.

[0040] 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.

[0041] As shown in FIG. 8 , the vibrating section 11 is formed so that the thickness T1 of the inner central portion 11a is thinner than the thickness T2 of the outer peripheral portion 11b. The vibration retaining portion 13a and the outer frame retaining portion 13b of the retaining portion 13 are formed to have substantially the same thickness, T3. The thickness T4 of the outer frame portion 12 is greater than the thicknesses of the vibrating section 11 and the retaining portion 13. One end of the retaining portion 13 (the end of the vibration retaining portion 13a) is connected to the central portion in the thickness direction of the outer peripheral portion 11b of the vibrating section 11. The other end of the retaining portion 13 (the end of the outer frame retaining portion 13b) is connected to the central portion in the thickness direction of the inner peripheral wall of the outer frame portion 12. As shown in FIG. 8 , the cross-sectional shapes of the vibrating section 11, the retaining portion 13, and the outer frame portion 12 taken along X1-X1 in FIG. 4 are vertically symmetrical.

[0042] 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.

[0043] Furthermore, the relationship of thickness T4 of outer frame portion 12 > thickness T2 of outer peripheral portion 11b of vibrating portion 11 > thickness T3 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 vibrating portion 11, retaining portion 13, and outer frame portion 12 are symmetrical in the thickness direction (up and 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.

[0044] 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 T4 of outer frame portion 12 > thickness T2 of outer peripheral portion 11b of vibrating portion 11 > thickness T3 of holding portion 13 ≥ thickness T1 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Furthermore, in this embodiment, 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. This allows the first escape routing 113 and the second escape routing 114 to be routed along the shortest possible route. This allows the lengths of the first escape routing 113 and the second escape routing 114 to be shortened, thereby reducing the resulting parasitic capacitance.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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, as shown in FIG. 9 , the outer frame retaining portion 13b may be V-shaped, bent at a predetermined angle, or may be arc-shaped or elliptical-shaped. In the example shown in FIG. 9 , 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 (connections) between the vibration retaining portion 13a and the outer frame retaining portion 13b is an even number, and that the number of connection points on the outer frame retaining portion 13b is a multiple of the number of connection points on the vibration retaining portion 13a.

[0056] 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.

[0057] In the above embodiment, no through-holes are provided in the outer frame 12 of the quartz crystal plate 10. However, through-holes may be provided in the outer frame 12 and electrical connections may be established using through-hole electrodes in the through-holes, or by cutting out portions of the side surfaces of the quartz crystal plate 10 and forming castellations with electrodes on the inner wall surfaces of the cut-out regions to establish electrical connections. For example, as shown in Figures 10 and 11, five through-holes 12g, 12h may be formed in the quartz crystal plate 10, penetrating between the first main surface 101 and the second main surface 102. In the example shown in Figures 10 and 11, four through-holes 12g are provided in the four corner regions of the outer frame 12, and the four through-holes 12g are located on the extension lines of the outer frame holding portions 13b of the holding portion 13. Furthermore, one through-hole 12h is 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 Figures 10 and 11). Around each of the four through-holes 12g, a connection bonding pattern 12i is formed on the first main surface 101 side, and a connection bonding pattern 12j is formed on the second main surface 102 side. Around each of the through-holes 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. In each of the five through-holes 12g, 12h, a through electrode for establishing electrical continuity between the electrodes formed on the first main surface 101 and the second main surface 102 is formed along the inner wall surface of each of the through-holes 12g, 12h. The central portions of the five through holes 12 g and 12 h are hollow through-holes that penetrate between the first main surface 101 and the second main surface 102 .

[0058] 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. 12 and 13 , 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 example of FIGS. 12 and 13 , 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 example of FIGS. 12 and 13 , 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.

[0059] 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.

[0060] 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.

[0061] 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. 12, 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 the 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.

[0062] 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.

[0063] 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.

[0064] 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 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, 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).

[0065] 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.

[0066] This application claims priority from Japanese Patent Application No. 2024-54789, filed on March 28, 2024, the entire contents of which are incorporated herein by reference.

[0067] DESCRIPTION OF SYMBOLS 10 Quartz crystal vibration plate (piezoelectric vibration plate) 11 Vibration portion 11a Central portion 11b Outer peripheral portion 12 Outer frame 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 straight line L2 Second imaginary straight line T1 Thickness of central portion T2 Thickness of outer peripheral portion T3 Thickness of holding portion T4 Thickness of outer frame portion

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 wherein the relationship of thickness of the outer frame section > thickness of the outer peripheral section of the vibrating section > thickness of the retaining section is satisfied, and one end of the retaining section is connected to the center part in the thickness direction of the outer peripheral section of the vibrating section, and the other end of the retaining section is connected to the center part in the thickness direction of the outer frame 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 as described in claim 1, wherein the vibration portion is formed so that the thickness of the inner central portion is thinner than that of the outer peripheral portion, and the relationship of thickness of the outer frame portion > thickness of the outer peripheral portion of the vibration portion > thickness of the holding portion ≥ thickness of the central portion of the vibration portion is satisfied.

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

5. A piezoelectric diaphragm as described in claim 4, wherein an extraction electrode is formed that extends the excitation electrode of the vibrating part to the outer frame part via the holding part, and the vibration holding part of the holding part is connected to the end of the outer periphery of the vibrating part in the X-axis direction.

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.

Images