Piezoelectric Vibration Plate and Piezoelectric Vibration Device

Abstract

A crystal diaphragm (10) is provided with a vibration unit (11), an outer frame (12) which surrounds the outer periphery of the vibration unit (11), and a holding unit (13) which links the vibration unit (11) and the outer frame (12), wherein flat sections (13a, 13b) are provided on each of a pair of facing first and second primary surfaces of the holding unit (13), and on one flat section (13b), the width of the holding unit (13) in the width direction is greater than that of the other flat section (13a).

Description

[Technical field]

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

[0002] In recent years, the operating frequencies of various electronic devices have become higher and their packages have become smaller (especially lower profile). As a result, there is a demand for piezoelectric vibration devices (e.g., quartz crystal resonators, quartz crystal oscillators, etc.) to accommodate the higher frequencies and smaller packages.

[0003] In this type of piezoelectric vibration device, the housing is configured as a roughly rectangular parallelepiped package. This package is configured of a first sealing member and a second sealing member made of, for example, glass or quartz, and a piezoelectric vibration plate made of, for example, quartz and having excitation electrodes formed on both main surfaces, and the first sealing member and the second sealing member are laminated and bonded via the piezoelectric vibration plate. Then, the vibration part (excitation electrode) of the piezoelectric vibration plate arranged inside the package (internal space) is hermetically sealed (for example, Patent Document 1). Hereinafter, such a laminated form of a piezoelectric vibration device is referred to as a sandwich structure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-252051 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned piezoelectric vibration device, the piezoelectric vibration plate has a structure including a vibration part, an outer frame part surrounding the outer periphery of the vibration part, and a holding part (bridge part) connecting the vibration part and the outer frame part. That is, the piezoelectric vibration plate has a structure in which the vibration part, the holding part, and the outer frame part are integrally provided by a piezoelectric substrate made of quartz or the like. However, there is a problem that the holding part of the piezoelectric vibration plate is prone to breaking. The cause of this is thought to be that a thin area is formed on the side of the holding part when the piezoelectric vibration plate is processed by wet etching.

[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 the occurrence of breakage at the holding portion, and a piezoelectric vibration device equipped with such a piezoelectric vibration plate. [Means for solving the problem]

[0007] The present invention provides a means for solving the above-mentioned problems as follows. That is, the present invention provides a piezoelectric diaphragm including a vibration section, an outer frame section surrounding the outer periphery of the vibration section, and a holding section connecting the vibration section and the outer frame section, the holding section having a pair of opposing first and second main surface sections each provided with a flat section, and one of the flat sections of the first and second main surface sections has a flat section that is inclined toward the holding section. The holding portion is a direction perpendicular to the thickness direction of the piezoelectric diaphragm and a direction extending toward the outer frame portion. The width of the flat part along the width direction is longer than that of the other flat part. The piezoelectric diaphragm is an AT-cut quartz crystal plate, the first and second principal surfaces are arranged parallel to the XZ' plane of the AT-cut, the first principal surface is arranged on the +Y direction side, and the second principal surface is arranged on the -Y direction side. It is characterized by:

[0008] According to the above-mentioned configuration, when processing the piezoelectric diaphragm by wet etching, the thin-walled region formed on one end side of the holding portion in the width direction can be made small, and the strength of the holding portion can be ensured. This makes it possible to prevent the holding portion of the piezoelectric diaphragm from breaking.

[0009] The present invention also provides a piezoelectric diaphragm including a vibration section, an outer frame section surrounding an outer periphery of the vibration section, and a holding section connecting the vibration section and the outer frame section, the holding section having a pair of opposing first and second main surface sections each provided with a flat section, and one of the flat sections of the first and second main surface sections has a flat section that is in contact with the holding section. The holding portion is a direction perpendicular to the thickness direction of the piezoelectric diaphragm and a direction extending toward the outer frame portion. one end in the width direction is located closer to the one end in the width direction than the other flat portion, The piezoelectric diaphragm is an AT-cut quartz crystal plate, the first and second principal surfaces are arranged parallel to the XZ' plane of the AT-cut, the first principal surface is arranged on the +Y direction side, and the second principal surface is arranged on the -Y direction side. It is characterized by:

[0010] According to the above-mentioned configuration, when processing the piezoelectric diaphragm by wet etching, the thin-walled region formed on one end side of the holding portion in the width direction can be made small, and the strength of the holding portion can be ensured. This makes it possible to prevent the holding portion of the piezoelectric diaphragm from breaking.

[0011] In the above configuration, it is preferable that the other ends of the flat parts of the first and second main surface parts in the width direction of the holding part are provided at approximately the same positions in the width direction of the holding part.

[0012] In addition, in the above configuration ,before It is preferable that only one holding portion is provided, and that the holding portion extends from a corner portion on the +X direction side and the -Z direction side of the vibrating portion toward the -Z' direction side.

[0013] The present invention may also be a piezoelectric vibration device having a piezoelectric vibration plate having any of the above configurations, characterized in that a first sealing member covering one main surface side of the vibration part of the piezoelectric vibration plate and a second sealing member covering the other main surface side of the vibration part of the piezoelectric vibration plate are provided, and the first sealing member and the piezoelectric vibration plate are joined, and the second sealing member and the piezoelectric vibration plate are joined to seal the vibration part of the piezoelectric vibration plate. According to a piezoelectric vibration device having a piezoelectric vibration plate having the above configuration, the same effect as the above-mentioned piezoelectric vibration plate can be obtained. That is, when a piezoelectric vibration plate with a frame in which the vibration part and the outer frame part are connected by a holding part is used, it is possible to reduce the size and height of the piezoelectric vibration device, but in such a piezoelectric vibration device that is reduced in size and thickness, it is possible to suppress the occurrence of bending at the holding part of the piezoelectric vibration plate. Effect of the Invention

[0014] According to the present invention, it is possible to provide a piezoelectric vibration plate capable of suppressing the occurrence of breakage at a holding portion, and a piezoelectric vibration device including such a piezoelectric vibration plate. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a schematic diagram showing each component of the crystal resonator according to the present embodiment. [Diagram 2] 2 is a schematic plan view of a first main surface side of a first sealing member of the quartz crystal unit. FIG. [Diagram 3] 4 is a schematic plan view of a second principal surface side of a first sealing member of the quartz crystal unit. FIG. [Figure 4] 1 is a schematic plan view of a first main surface side of a quartz crystal plate according to an embodiment of the present invention. [Diagram 5] 2 is a schematic plan view of a second main surface side of the quartz crystal plate according to the present embodiment. FIG. [Figure 6] 4 is a schematic plan view of a first main surface side of a second sealing member of the quartz crystal unit. FIG. [Figure 7] 4 is a schematic plan view of a second principal surface side of a second sealing member of the quartz crystal unit. FIG. [Figure 8]5 is a cross-sectional view taken along line A1-A1 of FIG. 4. [Figure 9] 8 and shows a quartz crystal plate according to a first modified example. FIG. [Figure 10] 8 and shows a quartz crystal plate according to Modification 2. FIG. [Figure 11] 8 and shows a quartz crystal plate according to a third modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 vibration plate (piezoelectric vibration plate) 10, a first sealing member 20, and a second sealing member 30. In this quartz crystal unit 100, the quartz crystal vibration plate 10 and the first sealing member 20 are bonded together, and the quartz crystal vibration plate 10 and the second sealing member 30 are bonded together to form a package having a substantially rectangular 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 vibration plate 10, respectively, to form an internal space (cavity) of the package, and the vibration 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 small and low-profile. In addition, in order to achieve the small size, the package does not form castellations, but uses through-holes (described later) to achieve electrical continuity between electrodes. The crystal unit 100 is electrically connected to an external circuit board (not shown) provided externally via solder.

[0019] Next, the quartz crystal plate 10, the first sealing member 20, and the second sealing member 30 in the above-mentioned quartz crystal unit 100 will be described with reference to Figs. 1 to 7. Note that the following describes each of the components that are configured as separate units that are not joined together. Figs. 2 to 7 merely show examples of the configuration of the quartz crystal plate 10, the first sealing member 20, and the second sealing member 30, and do not limit the present invention.

[0020] As shown in FIG. 4 and FIG. 5, the quartz crystal vibrating plate 10 according to this embodiment is a piezoelectric substrate made of quartz crystal, and both main surfaces (first main surface 101, second main surface 102) are formed as flat and smooth surfaces (mirror finish). 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 FIG. 4 and FIG. 5, both main surfaces 101, 102 of the quartz crystal vibrating plate 10 are XZ' planes. In this XZ' plane, the direction parallel to the short side direction (short side direction) of the quartz crystal vibrating plate 10 is the X-axis direction, and the direction parallel to the long side direction (long side direction) of the quartz crystal vibrating plate 10 is the Z'-axis direction. The AT-cut is a processing technique in which the artificial quartz crystal is cut at an angle of 35°15' around the X-axis with respect to the Z-axis, which is one of the three crystal axes of the artificial quartz crystal, that is, 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 that are inclined at approximately 35°15' from the Y-axis and Z-axis of the quartz crystal (this cutting angle may be changed somewhat within the range 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.

[0021] A pair of excitation electrodes (first excitation electrode 111, second excitation electrode 112) are formed on both main surfaces 101, 102 of the quartz crystal vibration plate 10. The quartz crystal vibration plate 10 has a vibration part 11 formed in a substantially rectangular shape, an outer frame part 12 surrounding the outer periphery of the vibration part 11, and a holding part (bridge part) 13 that holds the vibration part 11 by connecting the vibration part 11 and the outer frame part 12. That is, the quartz crystal vibration plate 10 is configured such that the vibration part 11, the outer frame part 12, and the holding part 13 are integrally provided. The holding part 13 extends (protrudes) from only one corner of the vibration part 11 located in the +X direction and the -Z' direction to the outer frame part 12 in the -Z' direction. A through part (slit) 10a that penetrates the thickness direction of the quartz crystal vibration plate 10 is provided between the vibration part 11 and the outer frame part 12. In this embodiment, the quartz crystal vibration plate 10 is provided with only one holding portion 13 that connects the vibration portion 11 and the outer frame portion 12, and the through portion 10a is formed continuously so as to surround the outer periphery of the vibration portion 11. The cross-sectional shape of the holding portion 13 will be described in detail later.

[0022] The first excitation electrode 111 is provided on the first main surface 101 side of the vibration section 11, and the second excitation electrode 112 is provided on the second main surface 102 side of the vibration section 11. Input / output lead wiring (first lead wiring 113, second lead wiring 114) is connected to the first excitation electrode 111 and the second excitation electrode 112 to connect these excitation electrodes to external electrode terminals. The first lead wiring 113 on the input side is led out from the first excitation electrode 111 and connected to a connection joint pattern 14 formed on the outer frame section 12 via the holding section 13. The second lead wiring 114 on the output side is led out from the second excitation electrode 112 and connected to a connection joint pattern 15 formed on the outer frame section 12 via the holding section 13.

[0023] Both main surfaces (first main surface 101, second main surface 102) of the quartz crystal vibration plate 10 are provided with diaphragm-side sealing portions for bonding the quartz crystal vibration plate 10 to the first sealing member 20 and the second sealing member 30. A diaphragm-side first bonding pattern 121 is formed as the diaphragm-side sealing portion of the first main surface 101, and a diaphragm-side second bonding pattern 122 is formed as the diaphragm-side sealing portion of the second main surface 102. The diaphragm-side first bonding pattern 121 and the diaphragm-side second bonding pattern 122 are provided on the outer frame portion 12, and are formed in an annular shape in a plan view.

[0024] As shown in Figs. 4 and 5, the quartz crystal vibration plate 10 has five through holes penetrating between the first main surface 101 and the second main surface 102. Specifically, the four first through holes 161 are provided in the four corners (corner portions) of the outer frame portion 12. The second through hole 162 is provided in the outer frame portion 12 on one side in the Z'-axis direction of the vibration portion 11 (the -Z'-direction side in Figs. 4 and 5). A connection bonding pattern 123 is formed around each of the first through holes 161. Also, a connection bonding pattern 124 is formed on the first main surface 101 side around the second through hole 162, and a connection bonding pattern 15 is formed on the second main surface 102 side around the second through hole 162.

[0025] In the first through-hole 161 and the second through-hole 162, 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 through-hole. The central portion of each of the first through-hole 161 and the second through-hole 162 is a hollow through portion penetrating between the first main surface 101 and the second main surface 102. The outer peripheral edge of the diaphragm-side first bonding pattern 121 is provided close 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 diaphragm-side second bonding pattern 122 is provided close to the outer peripheral edge of the second main surface 102 of the quartz crystal vibrating plate 10 (outer frame portion 12). In this embodiment, an example has been given in which five through holes are formed penetrating between the first main surface 101 and the second main surface 102, but instead of forming through holes, it is also possible to cut out a part of the side of the quartz vibration plate 10 and form a castellation with an electrode attached to the inner wall surface of the cut-out area (the same applies to the first sealing member 20 and the second sealing member 30).

[0026] 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 (the surface to be bonded to the quartz crystal vibrating plate 10) of this first sealing member 20 is formed as a flat and smooth surface (mirror-finished). Although the first sealing member 20 does not have a vibrating part, 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, and thermal deformation of the quartz crystal unit 100 can be suppressed. Furthermore, the orientations of the X-axis, Y-axis, and Z'-axis in the first sealing member 20 are also the same as those of the quartz crystal vibrating plate 10.

[0027] As shown in FIG. 2, the first sealing member 20 has a first main surface 201 (an outer main surface not facing the quartz crystal plate 10) formed with first and second terminals 22 and 23 for wiring and a metal film 28 for shielding (for earth connection). The first and second terminals 22 and 23 for wiring are provided as wiring for electrically connecting the first and second excitation electrodes 111 and 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 and 23 are provided at both ends in the Z′-axis direction, with the first terminal 22 provided on the +Z′-direction side and the second terminal 23 provided on the −Z′-direction side. The first and second terminals 22 and 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.

[0028] The metal film 28 is provided between the first and second terminals 22, 23 and is arranged at a predetermined interval from the first and second terminals 22, 23. The metal film 28 is provided in almost all of the regions of the first main surface 201 of the first sealing member 20 where the first and second terminals 22, 23 are not formed. 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.

[0029] 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 (corner) regions of the first sealing member 20. The fourth and fifth through holes 212, 213 are provided in the +Z' direction and -Z' direction in FIGS. 2 and 3, respectively.

[0030] In the third through hole 211 and the fourth and fifth through holes 212, 213, through electrodes for establishing electrical continuity between the electrodes formed on the first main surface 201 and the second main surface 202 are formed along the inner wall surfaces of the through holes. The central portions of the third through hole 211 and the fourth and fifth through holes 212, 213 are hollow through portions penetrating between the first main surface 201 and the second main surface 202. The through electrodes of the two third through holes 211, 211 diagonally positioned on the first main surface 201 of the first sealing member 20 (the third through hole 211 positioned at the corner in the +X direction and the +Z' direction in FIG. 2 and FIG. 3, and the third through hole 211 positioned at the corner in the -X direction and the -Z' direction) are electrically connected to each other by the metal film 28. Further, 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.

[0031] On the second main surface 202 of the first sealing member 20, a sealing member-side first bonding pattern 24 is formed 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. Also, on the second main surface 202 of the first sealing member 20, a connection bonding pattern 25 is formed around the third through hole 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. Furthermore, a connection bonding pattern 263 is formed on the opposite side (-Z' direction side) of the long axis direction of the first sealing member 20 with respect to the connection bonding pattern 261, and the connection bonding pattern 261 and the connection bonding pattern 263 are connected by a wiring pattern 27. 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.

[0032] 6 and 7, the second sealing member 30 is a rectangular parallelepiped substrate formed from a single AT-cut quartz crystal plate, and a first main surface 301 (the surface to be bonded to the quartz crystal vibration plate 10) of this second sealing member 30 is formed as a flat and smooth surface (mirror-finished). Note that, like the quartz crystal vibration plate 10, the second sealing member 30 also uses an AT-cut quartz crystal plate, and it is preferable that the orientations of the X-axis, Y-axis, and Z'-axis are the same as those of the quartz crystal vibration plate 10.

[0033] 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 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.

[0034] Four external electrode terminals 32 are provided on a second main surface 302 (the outer main surface not facing the quartz crystal plate 10) of the second sealing member 30, which are electrically connected to an external circuit board provided outside the quartz crystal unit 100. The external electrode terminals 32 are located at the four corners (corner portions) of the second main surface 302 of the second sealing member 30.

[0035] As shown in FIG. 6 and FIG. 7, the second sealing member 30 has four through holes formed between the first main surface 301 and the second main surface 302. Specifically, the four sixth through holes 33 are provided in the regions of the four corners (corner portions) of the second sealing member 30. In the sixth through holes 33, a through electrode for achieving electrical continuity between the electrodes formed on the first main surface 301 and the second main surface 302 is formed along the inner wall surface of each sixth through hole 33. In this way, the through electrode formed on the inner wall surface of the sixth through hole 33 provides electrical continuity between the electrode formed on the first main surface 301 and the external electrode terminal 32 formed on the second main surface 302. In addition, the center portion of each sixth through hole 33 is a hollow through portion that penetrates between the first main surface 301 and the second main surface 302. Moreover, on the first main surface 301 of the second sealing member 30, around each of the sixth through holes 33, a connection bonding pattern 34 is formed.

[0036] In the quartz crystal unit 100 including the quartz crystal vibration plate 10, the first sealing member 20, and the second sealing member 30 configured as above, the quartz crystal vibration plate 10 and the first sealing member 20 are diffusion bonded in a state where the diaphragm-side first bonding pattern 121 and the sealing member-side first bonding pattern 24 are overlapped, and the quartz crystal vibration plate 10 and the second sealing member 30 are diffusion bonded in a state where the diaphragm-side second bonding pattern 122 and the sealing member-side second bonding pattern 31 are overlapped, thereby manufacturing a sandwich-structured package as shown in Fig. 1. This causes the internal space of the package, i.e., the space housing the vibration part 11, to be hermetically sealed.

[0037] At this time, the above-mentioned connection bonding patterns are also diffusion bonded in a state of being overlapped with each other. By bonding the connection bonding patterns to each other, the crystal unit 100 is configured to obtain electrical conduction between the first excitation electrode 111, the second excitation electrode 112, and the external electrode terminal 32. Specifically, the first excitation electrode 111 is connected to the external electrode terminal 32 via the first lead wiring 113, the wiring pattern 27, the fourth through hole 212, the first terminal 22, the third through hole 211, the first through hole 161, and the sixth through hole 33 in this order. The second excitation electrode 112 is connected to the external electrode terminal 32 via the second lead wiring 114, the second through hole 162, the fifth through hole 213, the second terminal 23, the third through hole 211, the first through hole 161, and the sixth through hole 33 in this order. Moreover, the metal film 28 is connected to earth (ground connection, using a part of the external electrode terminal 32) via the third through-hole 211, the first through-hole 161, and the sixth through-hole 33 in this order.

[0038] In the quartz crystal unit 100, the various bonding patterns are preferably formed by laminating a plurality of layers on the quartz crystal plate, with a Ti (titanium) layer and an Au (gold) layer being formed from the bottom layer side by vapor deposition or sputtering. In addition, 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.

[0039] In the quartz crystal vibrator 100 configured as described above, the sealing portions (seal paths) 115, 116 that hermetically seal the vibration portion 11 of the quartz crystal vibrating plate 10 are formed in an annular shape in a plan view. The seal path 115 is formed by diffusion bonding (Au-Au bonding) of the above-mentioned vibration plate side first bonding pattern 121 and the sealing member side first bonding pattern 24, and the outer edge shape and inner edge shape of the seal path 115 are formed in a substantially octagonal shape. Similarly, the seal path 116 is formed by diffusion bonding (Au-Au bonding) of the above-mentioned vibration plate side second bonding pattern 122 and the sealing member side second bonding pattern 31, and the outer edge shape and inner edge shape of the seal path 116 are formed in a substantially octagonal shape.

[0040] In the quartz crystal unit 100 in which the seal paths 115, 116 are formed by diffusion bonding in this manner, the first sealing member 20 and the quartz crystal plate 10 have a gap of 1.00 μm or less, and the second sealing member 30 and the quartz crystal plate 10 have a gap of 1.00 μm or less. In other words, the thickness of the seal path 115 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 116 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). As a comparative example, the thickness of a conventional metal paste sealing material using Sn is 5 μm to 20 μm.

[0041] Next, the quartz crystal plate 10 according to this embodiment will be described with reference to FIGS.

[0042] As shown in Figures 4 and 5, the quartz crystal vibration plate 10 comprises a vibration portion 11 formed in an approximately rectangular shape, an outer frame portion 12 surrounding the outer periphery of the vibration portion 11, and a holding portion 13 connecting the vibration portion 11 and the outer frame portion 12, and the holding portion 13 is formed in a cross-sectional shape as shown in Figure 8.

[0043] Specifically, as shown in Fig. 8, a pair of opposing first and second principal surfaces of the holding portion 13 are arranged parallel to the XZ' plane of the AT cut, with the first principal surface being a surface arranged on the +Y direction side and the second principal surface being a surface arranged on the -Y direction side. The width direction of the holding portion 13 is parallel to the X-axis direction. Note that in Fig. 8, the first and second escape wirings 113, 114 formed on the first and second principal surfaces of the holding portion 13 are omitted from illustration.

[0044] The pair of opposing first and second principal surfaces of the holding part 13 are provided with flat parts 13a and 13b, respectively, which are parallel to the XZ' plane. Of the flat parts 13a and 13b of the first and second principal surfaces, the width of one flat part (flat part of the second principal surface) 13b along the width direction of the holding part 13 is longer than that of the other flat part (flat part of the first principal surface) 13a. In addition, in one flat part (flat part of the second principal surface) 13b, one end (end on the -X direction side) of the holding part 13 in the width direction is located closer to the one end side (-X direction side) in the width direction than the other flat part (flat part of the first principal surface) 13a. The other ends (ends on the +X direction side) of the holding part 13 in the width direction of the flat parts 13a and 13b of the first and second principal surfaces are provided at approximately the same position in the width direction of the holding part 13.

[0045] On the first main surface side of the holding part 13, one end in the width direction of the flat part 13a (the end on the -X direction side) is connected to an inclined part 13c inclined at a predetermined angle with respect to the flat part 13a. The other end in the width direction of the flat part 13a (the end on the +X direction side) is connected to an inclined part 13d inclined at a predetermined angle with respect to the flat part 13a.

[0046] On the second main surface side of the holding portion 13, one end in the width direction of the flat portion 13b (the end on the -X direction side) is connected to a right-angle portion 13e perpendicular to the flat portion 13b. The right-angle portion 13e is connected to the inclined portion 13c. The other end in the width direction of the flat portion 13b (the end on the +X direction side) is connected to the inclined portion 13f inclined at a predetermined angle with respect to the flat portion 13b. The inclined portion 13f is connected to the inclined portion 13d.

[0047] In this embodiment, the cross-sectional shape of the holding portion 13 is surrounded by the flat portion 13a on the first main surface side, the inclined portions 13c and 13d, and the flat portion 13b on the second main surface side, the right angle portion 13e, and the inclined portion 13f. The width of the flat portions 13a and 13b of the first and second main surfaces along the width direction of the holding portion 13 is longer for the flat portion 13b of the second main surface than for the flat portion 13a of the first main surface. In addition, the flat portion 13b of the second main surface is located closer to the end side in the width direction than the flat portion 13a of the first main surface when processing the quartz crystal plate 10 by wet etching. Such a cross-sectional shape of the holding portion 13 can be formed by providing a difference in the width of the holding portion 13 between the first and second main surfaces by photomask design. For example, the width of the photomask for the second main surface portion may be made larger than the width of the photomask for the first main surface portion by about 20 to 30 μm.

[0048] According to this embodiment, it is possible to suppress the occurrence of breakage at the holding portion 13 of the quartz crystal plate 10. In detail, when processing the quartz crystal plate 10 by wet etching, it is possible to reduce the thin-walled region (for example, the notch portion (constriction portion) 13g as shown in FIG. 9) formed at one end side in the width direction of the holding portion 13 (−X direction side). In this case, for example, as shown in FIG. 10, the width L1 in the X-axis direction of the notch portion 13g is reduced, and the thin-walled region formed at one end side in the width direction of the holding portion 13 (−X direction side) can be reduced, and the strength of the holding portion 13 can be ensured. This makes it possible to suppress the occurrence of breakage at the holding portion 13 of the quartz crystal plate 10.

[0049] 8 shows a state in which the notch 13g is not formed in the holding portion 13, and shows a state in which the width L1 of the notch 13g in the X-axis direction is 0. In order to prevent the occurrence of bending at the holding portion 13 of the quartz crystal plate 10, it is preferable to form the holding portion 13 as shown in FIG.

[0050] On the other hand, in Figs. 9 and 10, a cutout portion 13g having a substantially rectangular cross-sectional shape is formed on the second main surface of the holding portion 13, and the strength of the holding portion 13 is weakened at the cutout portion 13g. However, in this embodiment, the width of the holding portion 13 along the width direction is made longer at the flat portion 13b of the second main surface than at the flat portion 13a of the first main surface, and one end of the holding portion 13 in the width direction is positioned closer to the one end side in the width direction than the flat portion 13a of the first main surface. The flat portion 13b of the second main surface on which the cutout portion 13g is provided is longer than the flat portion 13a of the first main surface on which the cutout portion is not provided. Also, one end of the flat portion 13b of the second main surface on which the cutout portion 13g is provided is positioned closer to one end side in the width direction of the holding portion 13 than one end of the flat portion 13a of the first main surface on which the cutout portion is not provided. In this way, the width L1 of the cutout 13g in the X-axis direction can be made smaller to approximate the shape of the holder in Fig. 8, and the strength of the holder 13 can be ensured at the cutout 13g. This makes it possible to prevent breakage of the holder 13 of the quartz crystal plate 10.

[0051] In this embodiment, the quartz crystal vibration plate 10 includes a vibration portion 11, an outer frame portion 12 surrounding the outer periphery of the vibration portion 11, and a holding portion (bridge portion) 13 connecting the vibration portion 11 and the outer frame portion 12, and a through portion 10a penetrating in the thickness direction is provided between the vibration portion 11 and the outer frame portion 12. When using a framed quartz crystal vibration plate 10 in which the vibration portion 11 and the outer frame portion 12 are connected by the holding portion 13, it is possible to reduce the size and height of the quartz crystal unit 100, and in such a small and thin quartz crystal unit 100, the occurrence of breakage at the holding portion 13 of the quartz crystal vibration plate 10 can be suppressed.

[0052] Incidentally, in a quartz crystal vibrating plate 100 used at high frequencies (e.g., 60 to 80 MHz), the thickness of the vibrating portion 11 of the quartz crystal vibrating plate 100 is made thin in order to accommodate higher frequencies, and the thickness of the holding portion 13 is also made thin. This makes it difficult to stably form the shape of the holding portion 13 shown in FIG. 8 by wet etching.

[0053] 11, by forming the end of the -X direction of the holding portion 13 in a shape in which the thickness changes continuously, the holding portion 13 can be stably formed and the strength of the holding portion 13 can be ensured. Therefore, in the quartz crystal resonator 100 adapted to higher frequencies, the occurrence of breakage at the holding portion 13 of the quartz crystal plate 10 can be suppressed.

[0054] The holding portion 13 shown in Fig. 11 has a shape that does not have the right angle portion 13e of the holding portion 13 shown in Fig. 8. The cross-sectional shape of the holding portion 13 is a shape surrounded by a flat portion 13a, inclined portions 13c and 13d on the first main surface side, and a flat portion 13b and inclined portion 13f on the second main surface side. The flat portion 13b and the inclined portion 13c are connected.

[0055] Among the flat portions 13a and 13b of the first and second main surfaces, the width of one flat portion (flat portion of the second main surface) 13b along the width direction of the holding portion 13 is longer than that of the other flat portion (flat portion of the first main surface) 13a. In addition, in one flat portion (flat portion of the second main surface) 13b, one end (end on the -X direction side) of the holding portion 13 in the width direction is located closer to the one end side (-X direction side) in the width direction than the other flat portion (flat portion of the first main surface) 13a. The other ends (ends on the +X direction side) of the holding portion 13 in the width direction of the flat portions 13a and 13b of the first and second main surfaces are provided at approximately the same position in the width direction of the holding portion 13.

[0056] In a quartz crystal plate 100 used at high frequencies (e.g., 60 to 80 MHz), the thickness of the holding portion 13 is, for example, 30 μm, and the end of the -X direction of the flat portion 13b of the second principal surface is located, for example, 10 to 20 μm further toward the -X direction than the end of the flat portion 13a of the first principal surface. In other words, the distance L2 in FIG. 11 is 10 to 20 μm.

[0057] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention is not interpreted solely by the above-described embodiments, but is defined by the claims. Also, all modifications within the scope and meaning equivalent to the claims are included.

[0058] In the above embodiment, the quartz crystal vibration plate 10 is provided with only one holding portion (bridge portion) 13 connecting the vibration portion 11 and the outer frame portion 12, but two or more holding portions 13 may be provided, in which case the configuration of the above embodiment may be applied to each holding portion 13.

[0059] In the above embodiment, the thickness of the vibration portion 11 and the holding portion 13 of the quartz crystal vibration plate 10 may be thinner than the thickness of the outer frame portion 12.

[0060] 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 limiting, and the first sealing member 20 and the second sealing member 30 may be formed from, for example, glass. Furthermore, the first sealing member 20 and the second sealing member 30 are not limited to brittle materials such as quartz and glass, and may be a resin plate or a resin film, etc., in which case the vibration part 11 may be sealed by attaching the resin plate or the resin film, etc. to the quartz vibration plate 10.

[0061] In the above embodiment, a sandwich structure in which the quartz crystal vibrating plate 10 is sandwiched between the first sealing member 20 and the second sealing member 30 is used as the quartz crystal vibrator 100, but a quartz crystal vibrator 100 having a different structure may also be used. For example, a quartz crystal vibrator having a structure in which the quartz crystal vibrating plate 10 is housed inside a base having a recess and made of an insulating material such as ceramic, glass, or quartz crystal, and a lid is bonded to the base may also be used.

[0062] 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 to this and the number of external electrode terminals 32 may be, for example, two, six, or eight. In addition, although a case has been described in which the present invention is applied to the quartz crystal resonator 100, this is not limited to this and the present invention may also be applied to, for example, a quartz crystal oscillator or the like.

[0063] This application claims priority based on Japanese Patent Application No. 2021-091598, filed in Japan on May 31, 2021, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0064] 10 Quartz crystal plate (piezoelectric plate) 11 Vibration section 12 Outer frame 13 Holding part 13a,13b Flat part 100 Quartz crystal unit (piezoelectric vibration device)

Claims

1. A piezoelectric diaphragm including a vibration section, an outer frame section surrounding an outer periphery of the vibration section, and a holding section connecting the vibration section and the outer frame section, A pair of opposing first and second main surface portions of the holding portion are each provided with a flat portion, one of the flat portions of the first and second principal surface portions has a width greater than that of the other flat portion in a width direction of the holding portion, the width direction being perpendicular to a direction in which the holding portion extends toward the outer frame portion and a thickness direction of the piezoelectric diaphragm; The piezoelectric diaphragm is an AT-cut quartz crystal plate, The first and second principal surfaces are provided parallel to the XZ' plane of the AT cut, The piezoelectric diaphragm is characterized in that the first main surface portion is provided on the +Y direction side, and the second main surface portion is provided on the -Y direction side.

2. A piezoelectric diaphragm including a vibration section, an outer frame section surrounding an outer periphery of the vibration section, and a holding section connecting the vibration section and the outer frame section, A pair of opposing first and second main surface portions of the holding portion are each provided with a flat portion, one end of the holding portion in a width direction, which is a direction perpendicular to a direction in which the holding portion extends toward the outer frame portion and a thickness direction of the piezoelectric diaphragm, of one of the flat portions of the first and second principal surface portions is located closer to the one end side in the width direction than the other flat portion; The piezoelectric diaphragm is an AT-cut quartz crystal plate, The first and second principal surfaces are provided parallel to the XZ' plane of the AT cut, The piezoelectric diaphragm is characterized in that the first main surface portion is provided on the +Y direction side, and the second main surface portion is provided on the -Y direction side.

3. 3. The piezoelectric diaphragm according to claim 1, A piezoelectric diaphragm, characterized in that the other ends of the flat portions of the first and second main surface portions in the width direction of the holding portion are provided at approximately the same positions in the width direction of the holding portion.

4. 3. The piezoelectric diaphragm according to claim 1, Only one holding portion is provided, The piezoelectric diaphragm is characterized in that the holding portion extends from a corner portion on the +X direction side and the -Z direction side of the vibration portion toward the -Z direction side.

5. A piezoelectric vibration device, comprising: A piezoelectric vibration device comprising the piezoelectric vibration plate according to claim 1 or 2.

6. 6. The piezoelectric vibration device according to claim 5, a first sealing member covering one main surface side of the vibration portion of the piezoelectric diaphragm; a second sealing member that covers the other main surface side of the vibration portion of the piezoelectric diaphragm, A piezoelectric vibration device characterized in that the vibration portion of the piezoelectric vibration plate is sealed by bonding the first sealing member to the piezoelectric vibration plate and bonding the second sealing member to the piezoelectric vibration plate.

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