Double-rotating crystal diaphragm

Abstract

A doubly rotated quartz diaphragm comprising: a vibrating part 11 having first and second excitation electrodes 111, 112 formed on the obverse and reverse surfaces thereof; and an outer frame part 12 provided to the outer periphery of the vibrating part 11, wherein a penetrating portion 10a that penetrates in the thickness direction is provided between the vibrating part 11 and the outer frame part 12, the vibrating part 11 and the outer frame part 12 are connected by a holding part 13 extending in the Z'-axis direction at an end of the vibrating part 11 in the X'-axis direction orthogonal to the Z'-axis, and end electrodes 16, 17 where the ends of the vibrating part 11 in the Z'-axis direction on both main surfaces are configured to have the same electric potential are formed on the vibrating part 11 along opposing edges of the vibrating part 11 that extend in the X'-axis direction.

Description

Technical Field

[0004] , , , , , , , , , , , , , ,

[0005]

[0001] The present invention relates to a two-rotation crystal vibrating plate.

Background Art

[0002] Conventionally, as a crystal vibrating plate used in a crystal vibrating device such as a crystal oscillator, a two-rotation crystal vibrating plate such as an SC-cut crystal vibrating plate is known. The two-rotation crystal vibrating plate has an X-axis and a Z-axis along a plane orthogonal to the Y-axis, which is the crystal axis of the crystal. A Z'-axis is defined as an axis obtained by rotating the Z-axis around the X-axis, and an X'-axis is defined as an axis obtained by rotating the X-axis around the Z-axis. The two-rotation crystal vibrating plate is formed by cutting out from the planes along the Z'-axis and the X'-axis.

[0003] In such a two-rotation crystal vibrating plate, vibration in the C mode (thickness-shear vibration), which is the main vibration (fundamental wave), occurs. In addition to this, vibration in the B mode (thickness-torsion vibration) occurs in the vicinity of the frequency of the main vibration. Therefore, it has become an obstacle to exciting only at the frequency of the C mode of the main vibration.

[0004] In recent years, with the miniaturization of crystal vibrating devices, a three-layer crystal vibrating device in which a crystal oscillator is sandwiched between a first sealing member and a second sealing member has been proposed. However, when an SC-cut crystal vibrating plate is applied to such a three-layer crystal vibrating device, it is difficult to efficiently suppress the vibration in the B mode. As a method for suppressing the vibration in the B mode, for example, the method described in Patent Document 1 has been proposed, but there is a problem that it is low in practicality in terms of the difficulty of processing.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] This invention was made in consideration of the circumstances described above, and aims to provide a double-rotation quartz diaphragm that can efficiently suppress B-mode vibrations with a simple structure. [Means for solving the problem]

[0007] The present invention provides the following means for solving the above-mentioned problems. Specifically, the present invention provides a double-rotation quartz diaphragm cut from a plane along the Z' axis and X' axis, where the X axis and Z axis are perpendicular to the Y axis, which is the crystal axis of the quartz, the axis obtained by rotating the Z axis around the X axis is the Z' axis, and the axis obtained by rotating the X axis around the Z axis is the X' axis. The diaphragm comprises a vibrating portion with excitation electrodes formed on its front and back surfaces, and an outer frame portion provided on the outer circumference of the vibrating portion. A through portion is provided between the vibrating portion and the outer frame portion, penetrating in the thickness direction. The vibrating portion and the outer frame portion are connected by a holding portion extending in the Z' axis direction at the end of the vibrating portion in the X' axis direction perpendicular to the Z' axis. The vibrating portion has end electrodes formed along at least one of the opposing sides extending in the X' axis direction, such that the ends of the two main surfaces of the vibrating portion in the Z' axis direction are at the same potential. The cross-sectional shape of the vibrating part when cut in the Z'Y plane is a parallelogram, and the vibrating part has a shape in which the thickness decreases towards the ends in the Z' axis direction. It is characterized by the following:

[0008] With the above configuration, the B-mode vibration can be efficiently suppressed by a simple structure that includes end electrodes at the Z'-axis end of the vibrating part. Specifically, at the Z'-axis ends of both main surfaces of the vibrating part, which are at the same potential due to the end electrodes, the potential difference caused by the B-mode thickness torsional vibration is canceled out, thereby weakening the B-mode vibration intensity. In addition, the holding part extending in the Z'-axis direction can suppress the B-mode vibration. As a result, the C-mode vibration, which has a high vibration component in the X'-axis direction, can be detected with high accuracy, and oscillation can be made at the frequency of only the C-mode of the main vibration. Furthermore, since the vibrating section has a shape in which the thickness decreases towards the ends at both ends in the Z' axis direction, it is possible to make it difficult for secondary vibrations generated in the vibrating section (for example, vibrations of the contour system or bending system) to couple with C-mode vibrations due to thickness sliding vibrations.

[0009] In the above configuration, it is preferable that the end electrode is adjacent to the holding portion. With this configuration, since the holding portion and the end electrode are adjacent to each other along the X' axis direction, the vibration portion can be suppressed efficiently without unnecessarily expanding it, and B-mode vibrations can be effectively suppressed.

[0010] In the above configuration, it is preferable that the end electrodes are provided on both of the opposing sides of the vibrating portion in the X' axis direction. With this configuration, the field-free region where the potential is the same is enlarged by the end electrodes, and B-mode vibration can be efficiently suppressed.

[0011] In the above configuration, it is preferable that the excitation electrode reaches the region of the holding portion in the X' axis direction. This configuration is desirable for suppressing B-mode vibrations, and it is possible to secure the area of ​​the excitation electrode within the limited size of the vibrating portion and improve electrical characteristics such as the CI value of the C-mode.

[0012] In the above configuration, it is preferable that only one holding portion is provided. With this configuration, it is possible to suppress B-mode vibrations and make it difficult to suppress C-mode vibrations.

[0013] In the above configuration, if the end electrode is provided on the side of the vibrating portion that is not provided on the side of the opposing side in the X' axis direction that is not provided on the holding portion, it is preferable that the length of the end electrode in the X' axis direction is greater than or equal to the length of the excitation electrode in the X' axis direction, and that the end electrode and the excitation electrode overlap in the Z' axis direction. With this configuration, B-mode vibrations can be suppressed more efficiently.

[0015] In the above configuration, it is preferable that the inner ends of the end electrodes are positioned substantially aligned on the front and back surfaces of the vibrating portion. This configuration allows for the reliable formation of a field-free region without unnecessarily enlarging the end electrodes, and enables efficient suppression of B-mode vibrations.

[0016] In the above configuration, it is preferable that the holding portion does not extend in the X'-axis direction with respect to the excitation electrode. According to this configuration, since the end portion in the X'-axis direction of the vibrating portion is a free end, it is possible to miniaturize the vibrating portion and prevent it from adversely affecting the vibration in the C mode.

[0017] In the above configuration, between the end electrode and the Commendation excitation electrode, the interval is preferably 20 μm to 30 μm. According to this configuration, the vibration in the B mode can be effectively suppressed.

Advantages of the Invention

[0018] According to the present invention, the vibration in the B mode can be efficiently suppressed by a simple structure in which an end electrode is provided at the end portion in the Z'-axis direction of the vibrating portion.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a schematic configuration diagram schematically showing a crystal oscillator provided with a crystal vibration plate according to the present embodiment. [Figure 2] FIG. 2 is a schematic plan view of the first main surface side of the first sealing member provided in the crystal oscillator. [Figure 3] FIG. 3 is a schematic plan view of the second main surface side of the first sealing member provided in the crystal oscillator. [Figure 4] FIG. 4 is a schematic plan view of the first main surface side of the crystal vibration plate according to the present embodiment. [Figure 5] FIG. 5 is a schematic plan view of the second main surface side of the crystal vibration plate according to the present embodiment. [Figure 6] FIG. 6 is a schematic plan view of the first main surface side of the second sealing member provided in the crystal oscillator. [Figure 7] FIG. 7 is a schematic plan view of the second main surface side of the second sealing member provided in the crystal oscillator. [Figure 8] FIG. 8 is a cross-sectional view taken along line A1-A1 of FIG. 4. [Figure 9] FIG. 9 is a view corresponding to FIG. 4 of a crystal vibration plate according to another Embodiment 1. [Figure 10] FIG. 10 is a diagram corresponding to FIG. 8 of the quartz diaphragm according to another Embodiment 2. [Figure 11] FIG. 11 is a schematic configuration diagram schematically showing a first modification of the quartz resonator. [Figure 12] FIG. 12 is a cross-sectional view taken along line A2 - A2 of FIG. 11. [Figure 13] FIG. 13 is a diagram corresponding to FIG. 12 showing a second modification of the quartz resonator. MODE FOR CARRYING OUT THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0021] First, before describing the quartz diaphragm 10 according to the present embodiment, the basic structure of the quartz resonator 100 including the quartz diaphragm 10 according to the present embodiment will be described. As shown in FIG. 1, the quartz resonator 100 includes a quartz diaphragm 10, a first sealing member 20, and a second sealing member 30. In this quartz resonator 100, the quartz diaphragm 10 and the first sealing member 20 are joined, and the quartz diaphragm 10 and the second sealing member 30 are joined, thereby forming a package having a substantially rectangular parallelepiped sandwich structure. That is, in the quartz resonator 100, the first sealing member 20 and the second sealing member 30 are joined to each of the both main surfaces of the quartz diaphragm 10, thereby forming an internal space (cavity) of the package, and the vibrating portion 11 (see FIGS. 4 and 5) is hermetically sealed in this internal space.

[0022] The quartz resonator 100 has, for example, a package size of 1.0 × 0.8 mm, and is designed to be miniaturized and made low-profile. The quartz resonator 100 is electrically connected to an external circuit board (not shown) provided outside via solder.

[0023] Next, the crystal diaphragm 10, the first sealing member 20, and the second sealing member 30 of the crystal oscillator 100 described above will be explained with reference to Figures 1 to 7. Here, we will explain each component as a separate unit that is not joined together. Figures 2 to 7 merely show one example configuration of the crystal diaphragm 10, the first sealing member 20, and the second sealing member 30, and these do not limit the present invention.

[0024] As shown in Figures 4 and 5, the quartz diaphragm 10 is a piezoelectric substrate made of quartz, and both of its main surfaces (first main surface 101, second main surface 102) are formed as flat, smooth surfaces (mirror-finished). In this embodiment, a double-rotated quartz diaphragm is used as the quartz diaphragm 10, and more specifically, an SC-cut quartz plate is used. In the quartz diaphragm 10 shown in Figures 4 and 5, both main surfaces 101 and 102 of the quartz diaphragm 10 are considered to be the X'Z' plane. In this X'Z' plane, the direction parallel to the short side of the quartz diaphragm 10 is considered to be the X' axis direction, and the direction parallel to the long side of the quartz diaphragm 10 is considered to be the Z' axis direction. SC cutting is a processing method in which a plane perpendicular to the Y-axis of a quartz crystal is rotated by a predetermined angle (e.g., 33.5° or 34.0°) around the X-axis, and then cut from a plane rotated by a predetermined angle (e.g., 21° or 22°) around the Z-axis from the rotated position. The X'-axis direction and Z'-axis direction shown in Figures 4 and 5 represent the cutting direction when cutting an SC-cut quartz plate (the direction of each crystal axis after the two rotations described above) (the same applies to the Y-axis direction). Note that the cutting angles described above are just examples, and other angles may be used within the general range of SC cutting angles. For example, the angle of rotation of the plane perpendicular to the Y-axis around the X-axis can be set to approximately 33° to 35°, and the angle of rotation around the Z-axis from this rotated position can be set to approximately 22° to 24°.

[0025] A pair of excitation electrodes (first excitation electrode 111, second excitation electrode 112) are formed on both main surfaces 101 and 102 of the quartz crystal diaphragm 10. The quartz crystal diaphragm 10 has a vibrating section 11 formed in a substantially rectangular shape, an outer frame section 12 surrounding the outer circumference of the vibrating section 11, and a holding section 13 that holds the vibrating section 11 by connecting the vibrating section 11 and the outer frame section 12. In other words, the quartz crystal diaphragm 10 has a configuration in which the vibrating section 11, the outer frame section 12, and the holding section 13 are integrally provided. The holding section 13 extends (projects) from only one corner of the vibrating section 11 located in the +X' and -Z' directions to the outer frame section 12 in the -Z direction. A through section (slit) 10a is formed between the vibrating section 11 and the outer frame section 12. In this embodiment, the crystal diaphragm 10 is provided with only one holding portion 13 that connects the vibrating portion 11 and the outer frame portion 12, and the through portion 10a is continuously formed so as to surround the outer circumference of the vibrating portion 11.

[0026] 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 wires (first lead wire 113, second lead wire 114) 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 wire 113 is led out from the first excitation electrode 111, passes through the holding section 13, and connects to a connecting joint pattern 14 formed on the outer frame section 12. The second lead wire 114 is led out from the second excitation electrode 112, passes through the holding section 13, and connects to a connecting joint pattern 15 formed on the outer frame section 12. End electrodes 16 and 17 are formed at both ends of the vibrating section 11 in the Z' axis direction. The end electrodes 16 and 17 are positioned at a predetermined distance from the first excitation electrode 111 and the second excitation electrode 112, and are located between the first and second excitation electrodes 111 and 112. Details of the end electrodes 16 and 17 will be described later.

[0027] Both main surfaces (first main surface 101, second main surface 102) of the crystal diaphragm 10 are provided with diaphragm-side sealing portions for joining the crystal diaphragm 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 plan view.

[0028] Furthermore, as shown in Figures 4 and 5, the crystal diaphragm 10 has five through-holes that penetrate between the first main surface 101 and the second main surface 102. Specifically, four first through-holes 161 are provided in the four corners (corners) 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 vibrating portion 11 (the -Z' direction side in Figures 4 and 5). A connecting joint pattern 123 is formed around each of the first through-holes 161. In addition, a connecting joint pattern 124 is formed around the second through-hole 162 on the first main surface 101 side, and a connecting joint pattern 15 is formed on the second main surface 102 side.

[0029] The first through-hole 161 and the second through-hole 162 have through electrodes formed along the inner wall surface of each through-hole to ensure electrical conductivity between the electrodes formed on the first main surface 101 and the second main surface 102. The central portions of the first through-hole 161 and the second through-hole 162 are hollow through-holes that penetrate between the first main surface 101 and the second main surface 102. The outer edge of the diaphragm-side first bonding pattern 121 is located close to the outer edge of the first main surface 101 of the crystal diaphragm 10 (outer frame portion 12). The outer edge of the diaphragm-side second bonding pattern 122 is located close to the outer edge of the second main surface 102 of the crystal diaphragm 10 (outer frame portion 12). In this embodiment, an example was given in which five through-holes are formed penetrating between the first main surface 101 and the second main surface 102. However, instead of forming through-holes, a part of the side surface of the first sealing member 20 may be cut out, and a castellation may be formed in which electrodes are attached to the inner wall surface of the cut-out area (the same applies to the second sealing member 30).

[0030] As shown in Figures 2 and 3, the first sealing member 20 is a rectangular substrate formed from a single quartz plate, and the second main surface 202 of the first sealing member 20 (the surface that joins to the quartz diaphragm 10) is formed as a flat, smooth surface (mirror finish). Although the first sealing member 20 does not have a vibrating part, by using an SC-cut quartz plate similar to the quartz diaphragm 10, the thermal expansion coefficients of the quartz diaphragm 10 and the first sealing member 20 can be made the same, thereby suppressing thermal deformation in the quartz oscillator 100. Furthermore, the orientation of the X', Y', and Z' axes of the first sealing member 20 is the same as that of the quartz diaphragm 10. The first sealing member 20 may also use a quartz plate or glass with a cutting angle other than SC-cut (for example, AT-cut) (the same applies to the second sealing member 30).

[0031] As shown in Figure 2, the first main surface 201 of the first sealing member 20 (the outer main surface not facing the crystal diaphragm 10) has first and second terminals 22 and 23 for wiring and a metal film 28 for shielding (earth connection). The first and second terminals 22 and 23 for wiring are provided as wiring to electrically connect the first and second excitation electrodes 111 and 112 of the crystal diaphragm 10 and 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 on the +Z' side and the second terminal 23 on the -Z' 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. The metal film 28 is provided between the first and second terminals 22 and 23, and is positioned at a predetermined distance from the first and second terminals 22 and 23. The metal film 28 is provided in almost all areas of the first main surface 201 of the first sealing member 20 where the first and second terminals 22 and 23 are not formed. The metal film 28 is provided from the end in the +X' direction to the end in the -X' direction of the first main surface 201 of the first sealing member 20.

[0032] As shown in Figures 2 and 3, the first sealing member 20 has six through-holes that penetrate between the first main surface 201 and the second main surface 202. Specifically, four third through-holes 211 are provided in the four corners (corners) of the first sealing member 20. The fourth and fifth through-holes 212 and 213 are provided in the +Z' and -Z' directions, respectively, in Figures 2 and 3.

[0033] In the third through-hole 211 and the fourth and fifth through-holes 212 and 213, through electrodes are formed along the inner wall surface of each through-hole to ensure conductivity between the electrodes formed on the first main surface 201 and the second main surface 202. Furthermore, the central portions of the third through-hole 211 and the fourth and fifth through-holes 212 and 213 are hollow through-holes that penetrate between the first main surface 201 and the second main surface 202. The through electrodes of the two third through-holes 211, 211 located diagonally opposite each other on the first main surface 201 of the first sealing member 20 (the third through-hole 211 located at the +X' and +Z' corners in Figures 2 and 3, and the third through-hole 211 located at the -X' and -Z' corners) are electrically connected by a metal film 28. Furthermore, the through-electrode of the third through-hole 211, located at the corner in the -X' and +Z' directions, 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' and -Z' directions, and the through-electrode of the fifth through-hole 213 are electrically connected by the second terminal 23.

[0034] A first bonding pattern 24 on the second main surface 202 of the first sealing member 20 is formed, which serves as the first sealing portion on the sealing member side for bonding to the crystal diaphragm 10. The first bonding pattern 24 on the sealing member side is formed in an annular shape in plan view. In addition, on the second main surface 202 of the first sealing member 20, a connecting bonding pattern 25 is formed around the third through-hole 211. A connecting bonding pattern 261 is formed around the fourth through-hole 212, and a connecting bonding pattern 262 is formed around the fifth through-hole 213. Furthermore, a connecting bonding pattern 263 is formed on the side opposite to the connecting bonding pattern 261 in the longitudinal direction of the first sealing member 20 (-Z' direction side), and the connecting bonding pattern 261 and the connecting bonding pattern 263 are connected by a wiring pattern 27. The outer edge of the first bonding pattern 24 on the sealing member side is provided close to the outer edge of the second main surface 202 of the first sealing member 20.

[0035] As shown in Figures 6 and 7, the second sealing member 30 is a rectangular substrate formed from a single quartz plate, and the first main surface 301 of this second sealing member 30 (the surface that joins to the quartz diaphragm 10) is formed as a flat, smooth surface (mirror finish). It is desirable that the second sealing member 30 also uses an SC-cut quartz plate, similar to the quartz diaphragm 10, and that the orientation of the X', Y', and Z' axes is the same as that of the quartz diaphragm 10.

[0036] A second sealing member-side bonding pattern 31 is formed on the first main surface 301 of the second sealing member 30, which serves as a second sealing portion on the sealing member side for bonding to the crystal diaphragm 10. The second sealing member-side bonding pattern 31 is formed in an annular shape in plan view. The outer edge of the second sealing member-side bonding pattern 31 is provided close to the outer edge of the first main surface 301 of the second sealing member 30.

[0037] The second main surface 302 of the second sealing member 30 (the outer main surface not facing the crystal diaphragm 10) is provided with four external electrode terminals 32 that are electrically connected to an external circuit board provided outside the crystal oscillator 100. The external electrode terminals 32 are located at the four corners (corners) of the second main surface 302 of the second sealing member 30.

[0038] As shown in Figures 6 and 7, the second sealing member 30 has four through-holes that penetrate between the first main surface 301 and the second main surface 302. Specifically, the four sixth through-holes 33 are provided in the four corner regions of the second sealing member 30. Through electrodes are formed along the inner wall surface of each sixth through-hole 33 to ensure electrical conductivity between the electrodes formed on the first main surface 301 and the second main surface 302. In this way, the electrodes formed on the inner wall surface of the sixth through-holes 33 provide electrical conductivity between the electrode formed on the first main surface 301 and the external electrode terminal 32 formed on the second main surface 302. Furthermore, the central portion of each sixth through-hole 33 is a hollow through-hole that penetrates between the first main surface 301 and the second main surface 302. Furthermore, on the first main surface 301 of the second sealing member 30, connection joining patterns 34 are formed around the sixth through-hole 33.

[0039] In the crystal oscillator 100, which includes the crystal diaphragm 10, the first sealing member 20, and the second sealing member 30 as described above, the crystal diaphragm 10 and the first sealing member 20 are diffusion-bonded with the first bonding pattern 121 on the diaphragm side and the first bonding pattern 24 on the sealing member side superimposed, and the crystal diaphragm 10 and the second sealing member 30 are diffusion-bonded with the second bonding pattern 122 on the diaphragm side and the second bonding pattern 31 on the sealing member side superimposed, thereby manufacturing a sandwich-structure package as shown in Figure 1. As a result, the internal space of the package, that is, the space housing the vibrating part 11, is hermetically sealed.

[0040] In this process, the aforementioned connection patterns are also superimposed and diffusely bonded. Through the bonding of the connection patterns, electrical conductivity is achieved in the crystal oscillator 100 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 wire 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 that order. The second excitation electrode 112 is connected to the external electrode terminal 32 via the second lead wire 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 that order. Furthermore, the metal film 28 is connected to earth (ground connection, utilizing a portion of the external electrode terminal 32) via the third through-hole 211, the first through-hole 161, and the sixth through-hole 33 in that order.

[0041] In the quartz oscillator 100, it is preferable that the various bonding patterns consist of multiple layers stacked on a quartz plate, with the Ti (titanium) layer and Au (gold) layer formed from the bottom layer side by vapor deposition or sputtering. Furthermore, if the other wiring and electrodes formed on the quartz oscillator 100 have the same configuration as the bonding patterns, the bonding patterns, wiring, and electrodes can be patterned simultaneously, which is preferable.

[0042] In the crystal oscillator 100 configured as described above, the sealing portions (seal paths) 115 and 116 that hermetically seal the vibrating portion 11 of the crystal diaphragm 10 are formed in annular shape in plan view. The seal path 115 is formed by diffusion bonding (Au-Au bonding) of the diaphragm-side first bonding pattern 121 and the sealing member-side first bonding pattern 24 described above, and the outer and inner edge shapes of the seal path 115 are formed to be approximately octagonal. Similarly, the seal path 116 is formed by diffusion bonding (Au-Au bonding) of the diaphragm-side second bonding pattern 122 and the sealing member-side second bonding pattern 31 described above, and the outer and inner edge shapes of the seal path 116 are formed to be approximately octagonal.

[0043] In the quartz crystal oscillator 100 in which seal paths 115 and 116 are formed by diffusion bonding as described above, the gap between the first sealing member 20 and the quartz crystal diaphragm 10 is 1.00 μm or less, and the gap between the second sealing member 30 and the quartz crystal diaphragm 10 is 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 diaphragm 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 diaphragm 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, in conventional metal paste sealing materials using Sn, the gap is 5 μm to 20 μm.

[0044] In this embodiment, in the crystal diaphragm 10 with the above configuration, a through portion 10a is provided between the vibrating portion 11 and the outer frame portion 12, penetrating in the thickness direction of the crystal diaphragm 10. The vibrating portion 11 and the outer frame portion 12 are connected by a holding portion 13 extending in the Z' axis direction at the end of the vibrating portion 11 in the X' axis direction perpendicular to the Z' axis. The vibrating portion 11 has end electrodes 16 and 17 formed along the opposing sides of the vibrating portion 11 extending in the X' axis direction, such that the ends of the two main surfaces 101 and 102 of the vibrating portion 11 are at the same potential. This point will be explained with reference to Figures 4, 5, and 8.

[0045] As shown in Figure 8, the vibrating part 11 has inclined surfaces 11a and 11b formed at both ends in the Z' axis direction, inclined with respect to the vibration plane of the vibrating part 11. The inclined surfaces 11a and 11b are formed during wet etching of the quartz diaphragm 10 due to the anisotropy of the quartz. In the example in Figure 8, the cross-sectional shape of the vibrating part 11 when cut in the Z'Y plane is a parallelogram. The side surface of the vibrating part 11 on the +Z' direction side is an inclined surface 11a that is inclined at a predetermined angle with respect to the vibration plane of the vibrating part 11, and the side surface of the vibrating part 11 on the -Z' direction side is an inclined surface 11b that is inclined at approximately the same angle as the inclined surface 11a. Note that the inclined surfaces 11a and 11b may be inclined at different angles. Also, the inclined surfaces 11a and 11b may be curved slopes, stepped slopes, or slopes with minute bends.

[0046] As shown in Figure 8, an end electrode 16 is formed on the +Z' side end of the vibrating part 11, and an end electrode 17 is formed on the -Z' side end of the vibrating part 11. The end electrode 16 is integrally formed with a substantially rectangular first portion 16a formed on the surface (first main surface 101) of the +Z' side end of the vibrating part 11, a substantially rectangular second portion 16b formed on the back surface (second main surface 102) of the end, and a substantially rectangular third portion 16c formed on the side surface (inclined surface 11a). The end electrode 17 is integrally formed with a substantially rectangular first portion 17a formed on the surface (first main surface 101) of the -Z' side end of the vibrating part 11, a substantially rectangular second portion 17b formed on the back surface (second main surface 102), and a substantially rectangular third portion 17c formed on the side surface (inclined surface 11b).

[0047] The end electrodes 16 and 17 are formed to the same thickness as the first and second excitation electrodes 111 and 112. The end electrodes 16 and 17 are preferably made of a conductive material such as a metal with low electrical resistance, and in this case, they are made of the same material as the first and second excitation electrodes 111 and 112. The end electrodes 16 and 17 are formed together with the first and second excitation electrodes 111 and 112, the first and second lead wiring 113 and 114, etc., by sputtering and photolithography on the quartz diaphragm 10, on which the vibrating part 11, the outer frame part 12, the through part 10a, etc. are formed by wet etching. The end electrodes 16 and 17 are not electrically connected to the first and second excitation electrodes 111 and 112, and are provided electrically independently of the first and second excitation electrodes 111 and 112. The end electrodes 16 and 17 may be formed from a different material than the first and second excitation electrodes 111 and 112. Furthermore, the thickness of the end electrodes 16 and 17 may be made greater than the thickness of the first and second excitation electrodes 111 and 112 to reduce the electrical resistance of the end electrodes 16 and 17.

[0048] As shown in Figure 8, the first portion 16a of the end electrode 16 and the -Z' side end (inner end) of the second portion 16b are located at approximately the same position. The first portion 17a of the end electrode 17 and the +Z' side end (inner end) of the second portion 17b are located at approximately the same position. As shown in Figures 4 and 5, the first portion 16a of the end electrode 16 and the first excitation electrode 111 are separated by a predetermined distance L1, and the second portion 16b of the end electrode 16 and the second excitation electrode 112 are separated by the same distance L1. The first portion 17a of the end electrode 17 and the first excitation electrode 111 are separated by a predetermined distance L2, and the second portion 17b of the end electrode 17 and the second excitation electrode 112 are separated by the same distance L2. The distances L1 and L2 are set to be approximately the same size. The intervals L1 and L2 are set based on the size of the vibrating section 11, the sizes of the first and second excitation electrodes 111 and 112, etc.

[0049] As shown in Figures 4 and 5, the end electrodes 16 and 17 are positioned to sandwich the first and second excitation electrodes 111 and 112 in a plan view. The end electrodes 16 and 17 are provided along the opposing sides of the vibrating section 11 that extend in the X' axis direction. The first portion 16a of the end electrode 16 and the first portion 17a of the end electrode 17 have approximately the same length in the X' axis direction. The second portion 16b of the end electrode 16 and the second portion 17b of the end electrode 17 have approximately the same length in the X' axis direction. The end electrode 17 is provided adjacent to the holding section 13, and the end of the end electrode 17 on the +X' direction side reaches the holding section 13.

[0050] According to this embodiment, in the quartz diaphragm 10, the B-mode vibration can be efficiently suppressed by a simple structure in which end electrodes 16 and 17 are provided at the Z'-axis end of the vibrating portion 11. Specifically, at the Z'-axis ends of both main surfaces 101 and 102 of the vibrating portion 11, which are at the same potential due to the end electrodes 16 and 17, the potential difference caused by the thickness torsional vibration of the B-mode is canceled out, thereby weakening the vibration intensity of the B-mode. Furthermore, the B-mode vibration can be mechanically suppressed by the holding portion 13 extending in the Z'-axis direction. As a result, the C-mode vibration, which has a high vibration component in the X'-axis direction, can be detected with high accuracy, and oscillation can be made at the frequency of only the C-mode, which is the main vibration.

[0051] Furthermore, since the holding portion 13 and the end electrode 17 are adjacent to each other along the X' axis, the vibration portion 11 can be not unnecessarily enlarged, and B-mode vibration can be efficiently suppressed. In addition, since the end electrodes 16 and 17 are provided on both opposing sides of the vibration portion 11 in the X' axis direction, the field-free region where the potential is the same is enlarged by the end electrodes 16 and 17, and B-mode vibration can be efficiently suppressed.

[0052] In this embodiment, the first and second excitation electrodes 111 and 112 extend (protrude) to the region of the holding portion 13 in the X' direction, and the X' direction ends of the first and second excitation electrodes 111 and 112 overlap with a part of the holding portion 13 in the Z' direction. This is desirable for suppressing B-mode vibrations, and allows for securing the area of ​​the first and second excitation electrodes 111 and 112 within the limited size of the vibrating portion 11, thereby improving electrical characteristics such as the CI value of the C-mode. Furthermore, since only one holding portion 13 is provided, a configuration can be achieved that suppresses B-mode vibrations without adversely affecting C-mode vibrations.

[0053] Here, if the size of the rectangular vibrating section 11 is [400μm~600μm]×[400μm~600μm], and the sizes of the rectangular first and second excitation electrodes 111 and 112 are [250μm~300μm]×[250μm~300μm], then by setting the above-mentioned intervals L1 and L2 to, for example, 20μm~30μm, the B-mode vibration can be effectively suppressed. However, increasing the intervals L1 and L2 has the problem of reducing the suppression effect on the B-mode. Also, decreasing the intervals L1 and L2 has the problem of adversely affecting the C-mode as well.

[0054] Furthermore, in this embodiment, the cross-sectional shape of the vibrating part 11 is a parallelogram, and at both ends of the vibrating part 11 in the Z' axis direction, the thickness decreases towards the ends. This makes it difficult for secondary vibrations generated in the vibrating part 11 (for example, vibrations of the contour system or bending system) to couple with C-mode vibrations due to thickness sliding vibrations. Also, since the inner ends of the end electrodes 16 and 17 are positioned to be approximately the same on both main surfaces of the vibrating part 11 (first main surface 101, second main surface 102), a field-free region can be reliably formed without unnecessarily enlarging the end electrodes 16 and 17, and B-mode vibrations can be efficiently suppressed. Moreover, the holding part 13 is configured not to extend in the X' axis direction relative to the first and second excitation electrodes 111 and 112, and the end of the vibrating part 11 in the X' axis direction is a free end, so the vibrating part 11 can be miniaturized without adversely affecting C-mode vibrations. Furthermore, since the first and second lead wires 113 and 114 are configured not to extend in the X' axis direction relative to the first and second excitation electrodes 111 and 112, the weighting provided by the first and second lead wires 113 and 114 can be prevented from adversely affecting the C-mode vibration.

[0055] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of the present invention is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the equivalents of the claims.

[0056] In the above embodiment, the length of the end electrodes 16 and 17 in the X' axis direction was smaller than the length of the first and second excitation electrodes 111 and 112 in the X' axis direction. However, the embodiment is not limited to this, and the length of the end electrodes 16 and 17 in the X' axis direction may be greater than or equal to the length of the first and second excitation electrodes 111 and 112 in the X' axis direction, for example, as shown in Figure 9. The lengths of the end electrodes 16 and 17 in the X' axis direction may be the same or different.

[0057] In particular, in the case of an end electrode 16 provided on the side of the vibrating section 11 opposite in the X' axis direction that is not provided with the holding section 13, it is preferable that the length of the end electrode 16 in the X' axis direction be greater than or equal to the length of the first and second excitation electrodes 111 and 112 in the X' axis direction, so that the end electrode 16 and the first and second excitation electrodes 111 and 112 overlap in the Z' axis direction. In this case, the end electrode 16 may be formed over the entire side of the vibrating section 11 opposite in the X' axis direction that is not provided with the holding section 13. With these configurations, B-mode vibrations can be efficiently suppressed.

[0058] In the above embodiment, the holding portion 13 and the end electrode 17 on the -Z' direction side of the vibrating portion 11 are provided adjacent to each other (continuously), but the invention is not limited to this, and a predetermined distance may be provided between the holding portion 13 and the end electrode 17. Furthermore, the end electrodes 16 and 17 may be formed to reach the corners of the vibrating portion 11.

[0059] In the above embodiment, noise can be reduced by connecting the end electrodes 16 and 17 to ground, but the invention is not limited to this. The end electrodes 16 and 17 only need to be able to bring the ends of both main surfaces 101 and 102 of the vibrating part 11 in the Z' axis direction to the same potential. They may be floating electrodes not connected to any electrodes or wiring, or electrodes charged to a fixed potential of either positive or negative. In the above embodiment, the end electrodes 16 and 17 were configured such that the first parts 16a and 17a and the second parts 16b and 17b were electrically connected via the third parts 16c and 17c. However, the third parts 16c and 17c may be omitted, and the first parts 16a and 17a and the second parts 16b and 17b may be electrically connected by means such as wires. Furthermore, the end electrodes 16 and 17 may have different potentials, or they may be at the same potential. Furthermore, these end electrodes 16 and 17 may be used to adjust the electrical characteristics of the quartz diaphragm 10, such as frequency, by increasing or decreasing the thickness of the electrodes after they have been formed on the quartz diaphragm 10 (for example, by ion milling or partial milling).

[0060] In the above embodiment, end electrodes 16 and 17 are provided on both sides of the opposing sides of the vibrating section 11 extending in the X' axis direction. However, it is also possible to provide end electrodes on only one side. When providing end electrodes on only one side, it is preferable to provide the end electrodes on the side of the opposing sides of the vibrating section 11 in the X' axis direction that does not have a holding section 13. In this case, the end electrode 16 may be formed continuously from one end to the other of the side of the vibrating section 11 that does not have a holding section 13.

[0061] In the above embodiment, the cross-sectional shape of the vibrating part 11 is a parallelogram, but the cross-sectional shape of the vibrating part 11 is not particularly limited as long as the ends of both main surfaces 101 and 102 of the vibrating part 11 in the Z' axis direction are at the same potential. For example, the cross-sectional shape of the vibrating part 11 may be rectangular, or it may have a projection 11c as shown in Figure 10. That is, a projection 11c is formed at the end of the vibrating part 11, protruding in the thickness direction of the vibrating part 11, and the end electrode 17 is formed so as to cover the projection 11c.

[0062] The cross-sectional shape of the vibrating portion 11 shown in Figure 10 is substantially the same as the shape described in Figure 8 of the aforementioned Patent Document 1. In the quartz diaphragm described in Patent Document 1, as shown in Figure 10, a projection 11c is provided at the end of the vibrating portion 11 on the -Z' direction side, and an inclined surface 11d is formed on the projection 11c to suppress B-mode vibration. The quartz diaphragm 10 shown in Figure 10 is a modified example of the quartz diaphragm described in Patent Document 1, to which the end electrodes of the above embodiment are applied.

[0063] As shown in Figure 10, the end electrode 16 on the +Z' direction side of the vibrating part 11 has the same configuration as in the above embodiment, but the end electrode 17 on the -Z' direction side of the vibrating part 11 is provided so as to cover the projection 11c entirely. The end electrode 17 forms a portion at the -Z' direction end of the vibrating part 11 where both main surfaces 101 and 102 of the vibrating part 11 are at the same potential. As a result, in addition to the effect of canceling out B-mode vibration by forming a field-free region at the Z' axial end of the vibrating part 11 with the end electrodes 16 and 17, the effect of suppressing B-mode vibration by the inclined surface 11d of the projection 11c is also obtained. Thus, a synergistic effect is obtained in suppressing B-mode vibration.

[0064] In the above embodiment, the crystal diaphragm 10 was provided with only one holding portion 13 connecting the vibrating portion 11 and the outer frame portion 12, and the through portion 10a was formed continuously to surround the outer circumference of the vibrating portion 11. However, any configuration in which the through portion 10a is provided between the vibrating portion 11 and the outer frame portion 12 is acceptable, and the configuration of the crystal diaphragm 10 can be changed in various ways. For example, the crystal diaphragm 10 may be configured to have two or more holding portions 13 connecting the vibrating portion 11 and the outer frame portion 12. For example, in addition to the holding portion 13 of the above embodiment, a holding portion may be provided extending in the +Z direction from one corner of the vibrating portion 11 located in the +X' and +Z' directions, and the vibrating portion 11 may be held by two holding portions. Alternatively, a holding portion may be provided extending along the Z-axis direction from each of the four corners of the vibrating portion 11, and the vibrating portion 11 may be held by four holding portions.

[0065] In the above embodiment, the number of external electrode terminals 32 on the second main surface 302 of the second sealing member 30 was set to four, but the invention is not limited to this, and the number of external electrode terminals 32 may be, for example, two, six, or eight. Furthermore, although the present invention has been described in the case where it is applied to a quartz crystal oscillator 100, the invention is not limited to this, and the present invention may also be applied to, for example, a quartz oscillator.

[0066] Furthermore, in the above embodiment, the electrodes of the crystal oscillator 100 were mainly connected via through-holes, but the electrodes may also be connected via the inner wall, outer wall, or castellations provided on the side wall of the package of the crystal oscillator 100.

[0067] In the above embodiment, the first sealing member 20 and the second sealing member 30 were formed from a quartz plate, but the invention 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.

[0068] Furthermore, although the above embodiment described an example in which the present invention is applied to a three-layer crystal oscillator device in which an SC-cut crystal diaphragm is sandwiched between a first sealing member and a second sealing member, the present invention is not limited to this, and may also be applied to a crystal oscillator device in which an SC-cut crystal diaphragm is mounted inside a base made of ceramic or the like. This modified example will be described with reference to Figures 11 to 13.

[0069] In the modified examples 1 and 2 shown in Figures 11 to 13, the quartz oscillator 200 has a structure in which a quartz diaphragm 10 is placed inside a roughly rectangular base (housing) 210 made of ceramic or the like, and hermetically sealed by a lid 220. Specifically, an open recess 210a is formed, and the quartz diaphragm 10 is sealed inside the recess 210a in an hermetically sealed state. The lid 220 is fixed to the upper surface of the peripheral wall portion 210b surrounding the recess 210a via a sealing material (not shown). Suitable sealing materials include, for example, metal-based sealing materials such as Au-Su alloy or solder, but sealing materials such as low-melting-point glass may also be used. The inside of the base 210 is preferably a vacuum or a low-pressure atmosphere such as nitrogen or argon with low thermal conductivity.

[0070] Stepped portions 210c and 210d are formed on the bottom surface of the base 210. These stepped portions 210c and 210d are located at two of the four corners of the bottom surface of the base 210. Connection terminals 210e and 210f formed on the stepped surfaces of the stepped portions 210c and 210d are connected to lead wires 113 and 114 formed on the underside of the crystal diaphragm 10 via conductive adhesives 230 and 230. The crystal diaphragm 10 is mounted inside the base 210 in a cantilevered state. Examples of conductive adhesives 230 include silicone-based adhesives, polyimide-based adhesives, epoxy-based adhesives, brazing materials, and solder.

[0071] As the crystal diaphragm 10, an SC-cut crystal diaphragm with substantially the same structure as the crystal diaphragm 10 of the above embodiment (see Figure 9) is used, and end electrodes 16 and 17 are provided at both ends of the vibrating part 11 in the Z' axis direction. In the examples of Figures 11 to 13, there are differences from the above embodiment in the shape of the first and second lead-out wiring 113 and 114, the absence of through-holes in the outer frame part 12, and the absence of annular sealing part.

[0072] In the modified example 1 shown in Figures 11 and 12, stepped portions 210c and 210d are provided at two corners on the -Z' side of the bottom surface of the base 210, and connection terminals 210e and 210f are formed on the stepped surfaces of the stepped portions 210c and 210d. The first excitation electrode 111 of the first main surface 101 of the vibrating portion 11 is connected to the connection terminal 210e provided at the corners on the +X' and -Z' sides of the bottom surface of the base 210 via the first lead-out wiring 113. The first lead-out wiring 113 is routed to the back side (second main surface 102 side) via wiring (not shown) formed on the side of the corners on the +X' and -Z' sides of the outer frame portion 12, and is connected to the connection terminal 210e on the stepped surface of the stepped portion 210c by conductive adhesive 230. Meanwhile, the second excitation electrode 112 of the first main surface 102 of the vibrating section 11 is connected via a second lead wire 114 to a connection terminal 210f provided at the -X' and -Z' corners of the bottom surface of the base 210. The second lead wire 114 is connected to the connection terminal 210f on the stepped surface of the stepped section 210d by conductive adhesive 230 at the -X' and -Z' corners of the outer frame section 12.

[0073] In contrast, in the modified example 2 of Figure 13, stepped portions 210c and 210d are provided at two corners on the +Z' side of the bottom surface of the base 210, and connection terminals 210e and 210f are formed on the stepped surfaces of the stepped portions 210c and 210d. The first excitation electrode 111 of the first main surface 101 of the vibrating portion 11 is connected to the connection terminal 210e provided at the corners on the +X' and +Z' sides of the bottom surface of the base 210 via the first lead-out wiring 113. The first lead-out wiring 113 is routed to the back side (second main surface 102 side) via wiring (not shown) formed on the side of the corners on the +X' and +Z' sides of the outer frame portion 12, and is connected to the connection terminal 210e on the stepped surface of the stepped portion 210c by conductive adhesive 230. On the other hand, the second excitation electrode 112 of the first main surface 102 of the vibrating section 11 is connected via a second lead wire 114 to a connection terminal 210f provided at the corners on the -X' and +Z' sides of the bottom surface of the base 210. The second lead wire 114 is connected to the connection terminal 210f on the stepped surface of the stepped section 210d by conductive adhesive 230 at the corners on the -X' and +Z' sides of the outer frame section 12. In the example of Figure 13, compared to the examples of Figures 11 and 12, the crystal diaphragm 10 is supported at the +Z' end furthest from the holding section 13, so that the influence of the stress of the conductive adhesive 230 is less likely to affect the C-mode vibration.

[0074] This application claims priority under Japanese Patent Application No. 2023-026396, filed in Japan on February 22, 2023. By reference thereto, all its contents are incorporated into this application. [Explanation of Symbols]

[0075] 10. Crystal diaphragm (double-rotating crystal diaphragm) 10a Penetration 11 Vibration section 12 Outer frame 13 Holding part 16,17 End electrode 100 crystal oscillator 111 1st excitation electrode 112 2nd excitation electrode

Claims

1. The crystal diaphragm has an X-axis and a Z-axis along a plane perpendicular to the Y-axis, which is the crystal axis of the quartz. The axis obtained by rotating the Z-axis around the X-axis is called the Z'-axis, and the axis obtained by rotating the X-axis around the Z-axis is called the X'-axis. The diaphragm is a double-rotating quartz diaphragm cut from a plane along the Z'-axis and the X'-axis. The system comprises a vibrating section with excitation electrodes formed on its front and back surfaces, and an outer frame section provided on the outer periphery of the vibrating section, with a through-hole provided between the vibrating section and the outer frame section, extending in the thickness direction. The vibrating part and the outer frame are connected by a holding part extending in the Z' axis direction, at the end of the vibrating part in the X' axis direction perpendicular to the Z' axis. The vibrating portion has end electrodes formed along at least one of the opposing sides extending in the X' axis direction of the vibrating portion, such that the ends of the two main surfaces of the vibrating portion in the Z' axis direction are at the same potential. The cross-sectional shape of the vibrating part when cut in the Z'Y plane is a parallelogram. The aforementioned vibrating section is characterized in that, at both ends in the Z' axis direction, the thickness decreases towards the ends, and this is a double-rotating quartz diaphragm.

2. In the double-rotating quartz diaphragm according to claim 1, A double-rotating quartz diaphragm characterized in that the end electrode is adjacent to the holding portion.

3. In the double-rotating quartz diaphragm according to claim 1 or 2, A double-rotating quartz diaphragm characterized in that the end electrodes are provided on both of the opposing sides in the X' axis direction of the vibrating portion.

4. In the double-rotating quartz diaphragm according to claim 1 or 2, A double-rotating quartz diaphragm characterized in that the excitation electrode reaches the region of the holding portion in the X' axis direction.

5. In the double-rotating quartz diaphragm according to claim 1 or 2, A double-rotating quartz diaphragm characterized in that only one of the aforementioned holding parts is provided.

6. In the double-rotating quartz diaphragm according to claim 1 or 2, A double-rotating quartz diaphragm characterized in that, when the end electrode is provided on the side of the opposing side of the vibrating portion in the X' axis direction that is not provided, the length of the end electrode in the X' axis direction is greater than or equal to the length of the excitation electrode in the X' axis direction, and the end electrode and the excitation electrode are superimposed in the Z' axis direction.

7. In the double-rotating quartz diaphragm according to claim 1 or 2, A double-rotating quartz diaphragm characterized in that the inner ends of the end electrodes are provided at positions where they substantially coincide on the front and back surfaces of the vibrating part.

8. In the double-rotating quartz diaphragm according to claim 1 or 2, A double-rotating quartz diaphragm characterized in that the holding portion does not extend in the X' axis direction with respect to the excitation electrode.

9. In the double-rotating quartz diaphragm according to claim 1 or 2, A double-rotating quartz diaphragm characterized in that the distance between the end electrode and the excitation electrode is 20 μm to 30 μm.

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