Piezoelectric vibration element and piezoelectric device

Abstract

To provide a piezoelectric vibration element capable of improving a characteristic of vibration.SOLUTION: A crystal element 1 includes: a crystal raw plate 3; a pair of excitation electrodes 7; and a pair of leading electrodes 9. The crystal raw plate 3 is expanded in an X direction and a Z' direction orthogonal to the X direction, and includes a first end part 3a on one side of the X direction. The pair of excitation electrodes 7 overlap the crystal raw plate 3. The pair of leading electrodes 9 overlap the crystal raw plate 3, and is led toward the first end part 3a from the pair of excitation electrodes 7. The pair of leading electrodes 9 includes a pair of pad parts 9a which are separated from each other in the Z' direction. The crystal raw plate 3 includes a buffer part 11 positioned between the pair of pad parts 9a. The buffer part 11 may be separated from the pair of pad parts 9a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a piezoelectric vibration element and a piezoelectric device. [Background technology]

[0002] Known examples of piezoelectric devices include quartz crystal resonators and quartz crystal oscillators. These piezoelectric devices have a piezoelectric vibration element that vibrates when an AC voltage is applied to it. The piezoelectric vibration element has, for example, a plate-shaped piezoelectric plate (for example, a quartz crystal plate), a pair of excitation electrodes provided on a pair of main surfaces (the widest surfaces of the plate shape; the front and back of the plate shape; the same applies below) of the piezoelectric plate, and a pair of extraction electrodes drawn from the pair of excitation electrodes. The pair of extraction electrodes are bonded to pads of a package, for example, by a conductive bonding material. This allows the piezoelectric vibration element to be mounted in the package. Then, an AC voltage is applied to the pair of extraction electrodes, and the AC voltage is applied to the piezoelectric plate by the pair of excitation electrodes.

[0003] Patent Document 1 discloses a piezoelectric plate having a notch formed at one end in a plan view. The notch is located between a pair of extraction electrodes and adjacent to the pair of extraction electrodes in a plan view. The pair of extraction electrodes also have films formed on the inner surfaces of the notch.

[0004] Patent Document 2 discloses a piezoelectric plate having a vibration portion and a fixed portion that constitute different regions in a plan view. The vibration portion is, for example, a portion where a pair of excitation electrodes are provided, and is flat. The fixed portion is, for example, a portion where a pair of extraction electrodes are provided, and is thicker than the vibration portion. Patent Document 1 further proposes forming a recess and a through hole in the fixed portion. The recess and the through hole overlap the pair of extraction electrodes in a plan view. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-186231 A [Patent Document 2] JP 2020-191579 A Summary of the Invention [Problem to be solved by the invention]

[0006] It is anticipated that a piezoelectric vibration element and a piezoelectric device capable of improving vibration characteristics will be provided. [Means for solving the problem]

[0007] A piezoelectric vibration element according to one embodiment of the present disclosure comprises a piezoelectric plate extending in a first direction and a second direction perpendicular to the first direction and having a first end on one side of the first direction, a pair of excitation electrodes overlapping the piezoelectric plate, and a pair of extraction electrodes overlapping the piezoelectric plate and extending from the pair of excitation electrodes toward the first end, the pair of extraction electrodes having a pair of pad portions spaced apart from each other in the second direction, and the piezoelectric plate having a buffer portion, the buffer portion including at least one of a first through hole penetrating the piezoelectric plate in the thickness direction, a recess which thins the piezoelectric plate, and a notch which cuts out the first end of the piezoelectric plate, and is positioned between the pair of pad portions and spaced apart from the pair of pad portions.

[0008] A piezoelectric device according to one aspect of the present disclosure includes the above-described piezoelectric vibration element and a package in which the piezoelectric vibration element is mounted. Effect of the Invention

[0009] According to the above configuration, for example, it is possible to improve characteristics relating to vibration. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view of a quartz crystal vibration element according to a first embodiment. [Diagram 2] FIG. 2 is a partially cutaway perspective view of the quartz crystal vibration element of FIG. [Diagram 3] FIG. 2 is a perspective view showing an application example of the quartz crystal vibration element of FIG. [Figure 4] 4 is a cross-sectional view taken along line IV-IV in FIG. 3 . [Diagram 5] FIG. 11 is a partially cutaway perspective view of a quartz crystal vibration element according to a second embodiment. [Figure 6] FIG. 11 is a perspective view of a quartz crystal vibrating element according to a third embodiment. [Figure 7] FIG. 13 is a plan view showing a modified example of the buffer portion. [Figure 8] 8(a) and 8(b) are plan views showing modified examples of the position of the fixing portion of the quartz crystal vibrating element. [Figure 9] 9(a) and 9(b) are cross-sectional views showing modified examples of the thickness of the quartz crystal vibrating element. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a quartz crystal vibration element (hereinafter, simply referred to as a "quartz crystal element") according to an embodiment will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones. Similarly, the dimensional ratios and the like between the drawings do not necessarily correspond. Unless otherwise specified, a planar view refers to a view parallel to the Y' direction of the XY'Z' coordinate system shown in FIG. 1 etc.

[0012] In the description of the embodiments or modifications other than the first embodiment, basically, only the differences from the previously described aspects will be described. Any matters not specifically mentioned may be considered to be the same as the previously described aspects or may be inferred from the previously described aspects.

[0013] First Embodiment (Overview of quartz crystal elements) Fig. 1 is a perspective view of the quartz crystal element 1 according to the first embodiment. Fig. 2 is a perspective view of the quartz crystal element 1, with a portion of the quartz crystal element 1 cut away. The quartz crystal element 1 is, for example, generally configured to be rotationally symmetrical by 180° with respect to a center line CL parallel to the X-axis. Therefore, the perspective view of the quartz crystal element 1 viewed from the -Y' side is the same as Fig. 1.

[0014] The center line CL is a virtual line that passes through the crystal element 1 (or the center of the vibration part 13 or excitation electrode 7 described later) and is parallel to the X direction. The center is, for example, the geometric center (centroid), and is a point where the first moment of area with respect to any axis passing through that point is 0. The same applies to the centers described for other members or parts.

[0015] The crystal element 1 generates vibrations, for example, when an AC voltage is applied to it. This vibration is used, for example, to generate an oscillation signal whose signal strength (for example, voltage and / or current) oscillates at a certain frequency. In other words, the crystal element 1 is included, for example, in a crystal resonator or a crystal oscillator.

[0016] The quartz crystal element 1 has a quartz crystal plate 3, and a first conductor pattern 5A and a second conductor pattern 5B (hereinafter referred to as "conductor patterns 5", and there may be no distinction between the two) that overlap the quartz crystal plate 3. The two conductor patterns 5 are not short-circuited to each other. Each conductor pattern 5 has an excitation electrode 7 and an extraction electrode 9 that is extracted from the excitation electrode 7. In other words, the quartz crystal element 1 has a pair of excitation electrodes 7 and a pair of extraction electrodes 9 connected to the pair of excitation electrodes 7.

[0017] The pair of extraction electrodes 9 contribute to the mounting of the crystal element 1. Specifically, for example, as shown in FIG. 4 described later, the extraction electrodes 9 and pads 111 of the package 103 are bonded with a conductive bonding material 105 to mount the crystal element 1 in the package 103. Note that the crystal element 1 may be mounted on a member (e.g., a circuit board) other than the package 103, but for convenience, the description of the embodiment may be given on the assumption that it is mounted in the package 103. When an AC voltage is applied to the pair of extraction electrodes 9 via the package 103, an AC voltage (electric field) is applied to the crystal element plate 3 by the pair of excitation electrodes 7. This causes the crystal element plate 3 to vibrate.

[0018] The pair of extraction electrodes 9 are extracted to one side (the side of the first end 3a, the +X side) in the first direction (X direction) of the quartz crystal plate 3 relative to the pair of excitation electrodes 7, and are spaced apart from each other in a second direction (Z' direction) that intersects (e.g., perpendicular to) the first direction (at least a portion of each other). More specifically, for example, the extraction electrode 9 has a pad portion 9a bonded to the package 103, and a wiring portion 9b connecting the excitation electrode 7 and the pad portion 9a. And, on one main surface of the quartz crystal plate 3, the pair of pad portions 9a of the pair of extraction electrodes 9 are located apart from each other in the Z' direction.

[0019] The crystal blank 3 has a buffer section 11 between a pair of extraction electrodes 9 (a pair of pad sections 9a). In this embodiment, the buffer section 11 is configured by a through hole penetrating the crystal blank 3 in the thickness direction (Y' direction). When a distortion is applied to the crystal blank 3 from the outside (for example, the package 103) through the pair of extraction electrodes 9, the distortion is absorbed by the buffer section 11 (more precisely, the surrounding portion of the buffer section 11 of the crystal blank 3). This reduces the likelihood of distortion occurring in the region of the crystal blank 3 where the excitation electrodes 7 are arranged. As a result, for example, the likelihood of the vibration characteristics of the crystal element 1 deteriorating is reduced, and thus the likelihood of the electrical characteristics of the crystal element 1 deteriorating is reduced. The above-mentioned distortion is caused, for example, by the curing shrinkage of the bonding material 105 and / or the warping of the substrate section 107a (FIG. 4) of the package 103 described later. Examples of the distortion include a case where the crystal blank 3 is convex or concave on the +Y' side when viewed in the X direction.

[0020] The above is an overview of the quartz crystal element 1 according to the first embodiment. In this embodiment, the quartz crystal blank 3 is taken as an example having multiple regions (vibration portion 13, fixed portion 15, and intermediate portion 17) with different thicknesses. As described below, the multiple regions with different thicknesses contribute to increasing the frequency of the oscillation signal while ensuring the strength of the quartz crystal element 1. Furthermore, in this embodiment, the quartz crystal blank 3 is taken as an example having a second through hole 19 and a third through hole 21. As described below, these through holes contribute to improving the vibration characteristics of the quartz crystal element 1 and / or providing electrical conductivity between the front and back of the quartz crystal element 1.

[0021] The first embodiment will be described below in the following order. 1. Quartz element 1 (Figs. 1 and 2) 1.1. Quartz crystal substrate 3 (except for the description of the buffer portion 11) 1.1.1. Vibration part 13 1.1.2. Fixed part 15 1.1.3. Middle section 17 1.1.4. Second through hole 19 1.1.5.Third through hole 21 1.2. Conductor pattern 5 1.2.1.Excitation electrode 7 1.2.2.Extraction electrode 9 1.3. Positional Relationship Between Conductive Pattern 5 and Second Through Hole 19 and Third Through Hole 21 1.4.Buffer section 11 1.5. Manufacturing method of the crystal element 1 2. Example of use of crystal element 1 (Figs. 3 and 4) 3. Summary of the First Embodiment

[0022] (1. Quartz crystal element) The crystal element 1 is, for example, a so-called AT-cut crystal vibration element. That is, the crystal blank 3 is an AT-cut crystal piece. A pair of excitation electrodes 7 overlap both sides of the crystal blank 3 (more specifically, the vibration part 13 in this embodiment. The same applies in the following paragraphs). When a voltage is applied in the thickness direction of the crystal blank 3 by the pair of excitation electrodes 7, the crystal blank 3 generates a so-called thickness-shear vibration. The resonant frequency of this vibration (in other words, the oscillation frequency) is basically determined by the thickness of the crystal blank 3. The crystal element 1 may use the fundamental mode or the overtone mode. In the description of this embodiment, an aspect using the fundamental mode may be taken as an example.

[0023] Various dimensions of the quartz crystal element 1 (quartz crystal blank 3) may be set appropriately. Examples of dimensional ranges are given below. The length of the quartz crystal blank 3 in the X direction may be 500 μm or more and 1500 μm or less. The length of the quartz crystal blank 3 (vibration part 13, fixed part 15 and / or intermediate part 17) in the Z' direction may be 300 μm or more and 700 μm or less. The length of the vibration part 13 in the X direction may be 250 μm or more and 1000 μm or less (however, shorter than the length of the quartz crystal blank 3 in the X direction). The thickness of the vibration part 13 may be 16 μm or less. This corresponds to a frequency of approximately 100 MHz or more when using the fundamental vibration of thickness shear vibration in an AT-cut plate. The length of the fixed part 15 in the X direction may be 100 μm or more and 500 μm or less (however, shorter than the length of the quartz crystal blank 3 in the X direction). The thickness of the fixing portion 15 may be 50 μm or less.

[0024] (1.1. Crystal base plate) As described above, the quartz crystal blank 3 is, for example, an AT-cut quartz crystal piece. That is, when an orthogonal coordinate system XYZ consisting of an X axis (electrical axis), a Y axis (mechanical axis), and a Z axis (optical axis) in the quartz crystal is rotated about the X axis by 30° to 50° (for example, 35°15′) to define an orthogonal coordinate system XY'Z', the quartz crystal blank 3 is a plate having a pair of main surfaces that are basically parallel to the XZ' plane.

[0025] The relationship between the positive and negative X-axis and the configuration of the quartz crystal element 1 (from another perspective, the shape of the quartz crystal blank 3) may be the opposite of that shown in the figure. However, in the description of the embodiment, the description may be given on the premise of the relationship shown in the figure.

[0026] The planar shape of the quartz crystal blank 3 may be set as appropriate. In the illustrated example, the planar shape of the quartz crystal blank 3 is a rectangle having sides parallel to the Z'-axis and the X-axis. Other planar shapes of the quartz crystal blank 3 include, for example, a circle and an ellipse. Also included is a shape in which one or more of the four sides of the rectangle are curved (for example, arc) and bulge outward.

[0027] Note that the term "rectangle" includes squares and rectangles in the narrow sense. In addition, when referring to a rectangle or rectangular shape, unless otherwise specified, it does not have to be strictly a square or rectangular shape, and the corners may be chamfered, for example. The same applies to the description of the shapes of other parts of the quartz crystal plate 3 other than the planar shape. The same also applies to polygons other than a rectangle.

[0028] In the planar shape of the quartz crystal blank 3, the X direction (the direction in which the principal surfaces slide relative to each other in thickness shear vibration) may be the longitudinal direction, the Z' direction may be the longitudinal direction, or the length in the Z' direction may be equal to the length in the X direction. In the illustrated example, the quartz crystal blank 3 has the X direction as the longitudinal direction. In other words, the quartz crystal blank 3 has a long side parallel to the X axis and a short side parallel to the Z' axis.

[0029] The quartz crystal blank 3 may be fabricated, for example, by etching quartz crystal. In this case, due to the anisotropy of quartz crystal with respect to etching, the side surface of the quartz crystal blank 3 or each part thereof may have an inclined surface (a crystal surface in another perspective). However, in the description of this embodiment, illustration of such an inclined surface may be omitted, or the shape and dimensions may be described ignoring the existence of the inclined surface. In this case, the correspondence between the shape and dimensions of the quartz crystal blank 3 exemplified in the description of the embodiment and the actual shape and dimensions having the inclined surface may be reasonably determined in consideration of the characteristics of the quartz crystal element 1, etc. For example, if the side surface of the quartz crystal blank 3 (or each part) includes an inclined surface, and as a result, the positions of the main surface on the +Y' side and the main surface on the -Y' side in the XZ' plane are shifted from each other, depending on the direction of the shift, the description of the shape and dimensions of the quartz crystal blank 3 (or each part) may be interpreted as being based on the maximum shape and dimensions in planar perspective.

[0030] In this embodiment, as described above, the quartz crystal plate 3 has a vibrating portion 13 and a fixed portion 15 which form different regions in a plan view and have different thicknesses. The vibrating portion 13 is a portion where a pair of excitation electrodes 7 overlap and are excited by the pair of excitation electrodes 7. The fixed portion 15 is a portion where a pair of extraction electrodes 9 overlap and is fixed to the package 103. The fixed portion 15 is thicker than the vibrating portion 13. With this configuration, for example, the vibrating portion 13 can be made thin to enable high-frequency vibration, while the fixed portion 15 ensures the strength of the quartz crystal plate 3.

[0031] As described above, the quartz crystal plate 3 further has an intermediate portion 17 that constitutes the region between the vibrating portion 13 and the fixed portion 15 in a plan view. The intermediate portion 17 is thicker on the fixed portion 15 side. This can reduce the likelihood that the vibration of the vibrating portion 13 will be rapidly attenuated on the fixed portion 15 side, for example, and can reduce the crystal impedance.

[0032] These parts (vibration section 13, fixed section 15 and intermediate section 17) will be described in order below.

[0033] (1.1.1. Vibration part) The vibrating part 13 includes at least an inner region of the quartz crystal plate 3 in a planar view. The inner region here refers to a region that is away from the outer edge of the quartz crystal plate 3. More specifically, for example, the vibrating part 13 may include a region that includes the center of the quartz crystal plate 3 in a planar view.

[0034] The planar shape and dimensions of the vibration section 13 may be set appropriately. In the illustrated example, the planar shape of the vibration section 13 is a rectangle having sides parallel to the Z' axis and the X axis. Other planar shapes of the vibration section 13 include, for example, a circle and an ellipse. Also, a shape in which at least one of the four sides of a rectangle is curved (for example, an arc) and bulges outward can be given. In the planar shape of the vibration section 13, the X direction (the direction in which the main surfaces slide relative to each other in thickness shear vibration) may be the longitudinal direction, the Z' direction may be the longitudinal direction, or the length in the Z' direction may be equal to the length in the X direction.

[0035] For example, the vibrating part 13 occupies a relatively large portion of the area (area in plan view) of the quartz crystal plate 3. For example, the vibrating part 13 occupies more than half the area of ​​the quartz crystal plate 3. However, the vibrating part 13 may occupy less than half the area of ​​the quartz crystal plate 3.

[0036] The vibration part 13 is a flat plate parallel to the XZ' plane, and has main surfaces (first surface 23A and second surface 23B) parallel to the XZ' plane. The first surface 23A faces the +Y' side (one side in the thickness direction of the quartz crystal plate 3) and is perpendicular to the Y' axis (thickness direction). The second surface 23B faces the -Y' side (the other side in the thickness direction of the quartz crystal plate 3) and is perpendicular to the Y' axis (thickness direction). From another perspective, the first surface 23A and the second surface 23B are parallel to each other.

[0037] (1.1.2. Fixed part) The fixed portion 15 includes at least a part of the region on the outer periphery of the quartz crystal plate 3 in a plan view. From another perspective, the fixed portion 15 is adjacent to at least a part of the outer edge of the vibration portion 13 across the intermediate portion 17. The length over which the fixed portion 15 and the outer edge of the vibration portion 13 are adjacent to each other (the length in the direction along the outer edge of the vibration portion 13) may be set appropriately, as will be understood from the modified examples described below (Figures 8(a) and 8(b)). In the illustrated example, the fixed portion 15 is adjacent to the vibration portion 13 along one side of the rectangular vibration portion 13.

[0038] The direction in which the fixed portion 15 and the vibrating portion 13 are adjacent to each other across the intermediate portion 17 may be the X direction (the direction in which the principal surfaces slide relative to each other in thickness shear vibration) (as shown in the example) or the Z' direction. From another perspective, the adjacent direction may be the short-side direction of the vibrating portion 13, or the long-side direction of the vibrating portion 13, or such a distinction may not be possible. Furthermore, the relationship between the adjacent direction and the long-side direction of the quartz crystal plate 3 is also arbitrary.

[0039] The planar shape and dimensions of the fixed portion 15 may be set appropriately. For example, the fixed portion 15 may have a shape that follows the outer edge of the vibrating portion 13 with a constant width (example shown), or the shape of the edge on the vibrating portion 13 side may be different from the shape of the edge on the opposite side to the vibrating portion 13. In the example shown, the fixed portion 15 is rectangular with a long side parallel to one side of the vibrating portion 13.

[0040] In a direction (Z' direction in the illustrated example) perpendicular to the direction in which fixed portion 15 and vibrating portion 13 are adjacent to each other with intermediate portion 17 in between, fixed portion 15 may be smaller, equal to (in the illustrated example) or larger than vibrating portion 13. The length of fixed portion 15 in the adjacent direction (X direction in the illustrated example) is also arbitrary. In the illustrated example, the length of fixed portion 15 in the X direction is shorter than the length of vibrating portion 13 in the X direction.

[0041] The fixed portion 15 is, for example, a flat plate parallel to the XZ' plane, similar to the vibrating portion 13. However, the fixed portion 15 may have a shape that does not have a width that can be considered as a plate. The fixed portion 15 has a main surface (third surface 25A and fourth surface 25B) parallel to the XZ' plane, similar to the vibrating portion 13. The third surface 25A faces the +Y' side (one side in the thickness direction of the quartz crystal plate 3) and is perpendicular to the Y' axis (thickness direction). The fourth surface 25B faces the -Y' side (the other side in the thickness direction of the quartz crystal plate 3) and is perpendicular to the Y' axis (thickness direction). From another perspective, the third surface 25A and the fourth surface 25B are parallel to each other. From yet another perspective, the third surface 25A and the fourth surface 25B are parallel to the first surface 23A and the second surface 23B.

[0042] As described above, the fixed portion 15 is thicker than the vibrating portion 13. More specifically, the fixed portion 15 is higher on both sides in the thickness direction (Y' direction) than the vibrating portion 13. From another perspective, the third surface 25A facing one side (+Y' side) in the thickness direction is located closer to the one side than the first surface 23A facing the one side. Also, the fourth surface 25B facing the other side (-Y' side) in the thickness direction is located closer to the other side than the second surface 23B facing the other side.

[0043] The height from the first surface 23A to the third surface 25A and the height from the second surface 23B to the fourth surface 25B may be greater than the other or may be equal to each other. In this embodiment, the two heights are equal to each other. These heights may be smaller than, equal to, or greater than the thickness of the vibration section 13.

[0044] (1.1.3. Middle section) The intermediate portion 17 extends, for example, over approximately the entire edge of the vibration portion 13 on the fixed portion 15 side and / or the entire edge of the fixed portion 15 on the vibration portion 13 side. The size of the intermediate portion 17 in a plan view may be set appropriately. For example, in a direction (Z' direction in the illustrated example) perpendicular to the direction in which the fixed portion 15 and the vibration portion 13 are adjacent to each other via the intermediate portion 17, the intermediate portion 17 may be smaller, equal (in the illustrated example), or larger than the vibration portion 13 and / or the fixed portion 15. The length of the intermediate portion 17 in the adjacent direction (X direction in the illustrated example) is also arbitrary. In the illustrated example, the length of the intermediate portion 17 in the X direction is shorter than the length of the fixed portion 15 in the X direction.

[0045] As described above, the intermediate portion 17 is thicker toward the fixed portion 15 side. Specifically, the intermediate portion 17 has a fifth surface 27A and a sixth surface 27B that are inclined so as to be thicker toward the fixed portion 15 side. The fifth surface 27A faces one side (+Y' side) in the thickness direction and is inclined with respect to the first surface 23A in a direction in which the fixed portion 15 side is located on the one side with respect to the vibration portion 13 side. The sixth surface 27B faces the other side (-Y' side) in the thickness direction and is inclined with respect to the second surface 23B in a direction in which the fixed portion 15 side is located on the other side with respect to the vibration portion 13 side. Each of the fifth surface 27A and the sixth surface 27B is, for example, generally constituted by one plane.

[0046] The inclination angle of the fifth surface 27A and the inclination angle of the sixth surface 27B may be the same or different from each other. In the description of this embodiment, an example in which both are the same is taken. The specific magnitude of this inclination angle may be set appropriately. For example, the angle of the fifth surface 27A or the sixth surface 27B with respect to the normal line (Y'-axis from another point of view) of the main surface of the fixed part 15 or the vibration part 13 may be smaller than 45° or may be 45° or more.

[0047] The fifth surface 27A and the sixth surface 27B may be crystal surfaces that appear due to the anisotropy of the quartz crystal with respect to etching when the quartz crystal plate 3 is formed by etching. In this case, the crystal surface that appears (from another point of view, the inclination angle of the crystal surface) may be appropriately selected depending on the etching conditions. An example of the angle of the crystal surface with respect to the normal line (from another point of view, the Y'-axis) of the main surface of the fixed portion 15 or the vibrating portion 13 is, for example, about 55° (e.g., 53° to 57°). An example of the above angle in the case where the positive and negative signs of the X-axis are reversed from the illustrated example is about 27° (e.g., 25° to 29°).

[0048] The first surface 23A and the fifth surface 27A intersect with each other and form a corner in a side view or a cross-sectional view (when viewed in the Z' direction). Although not particularly shown, this corner may have a curve or a step when viewed extremely microscopically. In this case, the length of the curve or the height of the step is, for example, less than 0.1 μm. Furthermore, even if not viewed microscopically, the first surface 23A and the fifth surface 27A may have a curve or a step between them. Although the boundary between the first surface 23A and the fifth surface 27A has been described, the above description may be applied to the boundary between the second surface 23B and the sixth surface 27B.

[0049] The boundary between the first surface 23A and the fifth surface 27A and the boundary between the second surface 23B and the sixth surface 27B may be aligned or may be shifted from each other in the direction in which the intermediate portion 17 and the vibration portion 13 are adjacent to each other (the X direction in the illustrated example). When the positions are aligned, it goes without saying that a tolerance may exist.

[0050] The third surface 25A and the fifth surface 27A intersect with each other and form a corner in a side view or a cross-sectional view (when viewed in the Z' direction). Although not particularly shown, this corner may have a curve or a step when viewed microscopically. The height of this step (size in the Y' direction) is, for example, less than 1 μm. Although the boundary between the third surface 25A and the fifth surface 27A has been described, the above description may be applied to the boundary between the fourth surface 25B and the sixth surface 27B.

[0051] The boundary between the third surface 25A and the fifth surface 27A and the boundary between the fourth surface 25B and the sixth surface 27B may be aligned or may be shifted from each other in the direction in which the fixed portion 15 and the intermediate portion 17 are adjacent to each other (the X direction in the illustrated example). When the positions are aligned, it goes without saying that a tolerance may exist.

[0052] (1.1.4. Second through hole) The second through hole 19 is located on the first end 3a side (+X side, the side where the extraction electrode 9 is extracted, the side where the pad portion 9a is located) with respect to the excitation electrode 7. Such a second through hole 19, for example, reduces the contact area between the region excited by the excitation electrode 7 (the vibration portion 13 from another point of view) and the region fixed to the package 103 and whose vibration is restricted (the fixed portion 15 from another point of view), thereby contributing to reducing the likelihood that the latter region inhibits the vibration of the former region. In addition, for example, the conductive pattern 5 is formed on the inner surface of the second through hole 19, so that the second through hole 19 contributes to the conduction between the front and back of the crystal element 1.

[0053] The position, shape, and dimensions of the second through hole 19 may be set as appropriate. In the illustrated example, the second through hole 19 is located in the intermediate portion 17. Unlike the illustrated example, the second through hole 19 may be located in the fixed portion 15, or may span both the intermediate portion 17 and the fixed portion 15. A part of the edge of the second through hole 19 may or may not match a part of the edge of the intermediate portion 17 (illustrated example). Although not particularly illustrated, the second through hole 19 may be provided in, for example, a quartz crystal blank in which the intermediate portion 17 is not provided. Examples of such a quartz crystal blank include one in which the vibrating portion 13 and the fixed portion 15 are directly connected, and one whose entire thickness is constant.

[0054] When the region between the excitation electrode 7 and the first end 3a is divided into two or three equal parts in the X direction, the entirety or center of the second through hole 19 may be located, for example, in the range closest to the excitation electrode 7. If the positional relationship between the excitation electrode 7, the first end 3a, and the second through hole 19 varies depending on the position in the Z' direction, the above description may be based on the position of the center line CL, for example. Also, the second through hole 19 is located, for example, approximately in the center of the Z' direction range of the quartz crystal plate 3 (or the vibrating part 13 or the excitation electrode 7). In other words, the center of the second through hole 19 approximately coincides with the center line CL.

[0055] In the illustrated example, the second through hole 19 is slit-shaped extending in a direction (Z' direction) perpendicular to the direction (X direction) from the excitation electrode 7 to the first end 3a. From another perspective, the shape of the second through hole 19 in a plan view is an ellipse having long sides parallel to the Z' direction and short sides that are arc-shaped (e.g., semicircular) bulging outward. Although not particularly illustrated, the second through hole 19 may be, for example, approximately rectangular in shape in addition to the above.

[0056] The shape and dimensions of second through-hole 19 in the XZ' cross section may be approximately constant in the Y' direction (penetration direction) or may vary. An example of the latter is a mode in which a crystal plane inclined to the Y' axis appears on the inner surface of second through-hole 19. In this case, the position, shape, dimensions, etc. of second through-hole 19 described above or later may be those of the opening surface (fifth surface 27A or sixth surface 27B), for example.

[0057] The length of the second through hole 19 in the Z' direction (e.g., the maximum length in a plan view; the same applies to other parts in this paragraph below) may be, for example, 1 / 4 or more or 1 / 3 or more of the length of the quartz crystal plate 3 (or the vibrating portion 13) in the Z' direction. The length of the second through hole 19 in the X direction may be, for example, approximately the same as the width (length in the X direction) of the intermediate portion 17 (e.g., 80% or more of the former). Furthermore, the length of the second through hole 19 in the X direction may be, for example, 1 / 10 or less, 1 / 20 or less, or 1 / 30 or less of the length of the quartz crystal element 1 in the X direction.

[0058] (1.1.5. Third through hole) The third through hole 21 is provided at a position overlapping with the extraction electrode 9 (more specifically, the pad portion 9a) in a plan view. From another perspective, the third through hole 21 is provided in the fixed portion 15. The third through hole 21 may contribute to electrical conduction between the front and back of the crystal element 1, for example, by forming a conductor pattern 5 on its inner surface. Although not particularly shown, the third through hole 21 may be provided in a crystal blank that does not have a relatively thick fixed portion 15. Examples of such a crystal blank include one that has a constant thickness overall, and one in which the vibrating portion is thicker than the fixed portion (a so-called mesa-type crystal blank).

[0059] The number, position, shape, size, etc. of the third through holes 21 may be set appropriately. In the illustrated example, two third through holes 21 are provided. The two third through holes 21 are located on both sides of the center line CL (from another point of view, the buffer section 11; the same applies hereinafter in this paragraph). The positions of the two (or three or more) third through holes 21 may be line-symmetrical with respect to the center line CL (illustrated example), or may not be line-symmetrical. Furthermore, the shapes and sizes of the multiple third through holes 21 may be the same (and / or line-symmetrical) with each other (illustrated example), or may be different from each other.

[0060] The whole or center of each third through hole 21 may be located on the first end 3a side (+X side) with respect to the center of the fixed portion 15 or the center of the pad portion 9a. When the quartz crystal plate 3 (fixed portion 15) is divided into three equal parts in the Z' direction (when the length in the Z' direction differs depending on the position in the X direction, the length in the Z' direction of the third through hole 21 at the X direction position may be used as a reference), for example, the whole or center of each third through hole 21 may be located in one of the two regions on both sides. From another perspective, in the Z' direction, the interval between two third through holes 21 (the length of the non-arrangement region of the third through hole 21) or the distance between the centers may be, for example, 1 / 3 or more of the length in the Z' direction of the fixed portion 15. Of course, the position of the third through hole 21 may be different from the above.

[0061] In the illustrated example, the shape of the third through hole 21 in plan view is an ellipse with the long axis oriented in the Z' direction. Unlike the illustrated example, the shape of the third through hole 21 in plan view may be, for example, a polygonal shape (e.g., a rectangle), a circular shape, or a polygonal shape with arc-shaped sides that bulge outward. Also, contrary to the illustrated example, the length of the third through hole 21 in the X direction (the maximum length when it varies depending on the position in the Z' direction) may be greater than the length in the Z' direction (the maximum length when it varies depending on the position in the X direction).

[0062] The shape and dimensions of the XZ' cross section of third through hole 21 may be constant in the Y' direction (penetration direction) or may vary. An example of the latter is a mode in which a crystal plane inclined to the Y' axis appears on the inner surface of third through hole 21. In this case, the position, shape, dimensions, etc. of third through hole 21 described above or later may be those of the opening surface (third surface 25A or fourth surface 25B), for example.

[0063] In the illustrated example, the maximum diameter, circle-equivalent diameter, and maximum length in the Z' direction of the third through hole 21 are smaller than the maximum length in the Z' direction of the second through hole 19. The maximum diameter, circle-equivalent diameter, and / or maximum length in the X direction of the third through hole 21 may be smaller than, equal to, or larger than the length (width) in the X direction of the second through hole 19.

[0064] The diameter in the Z' direction of the third through hole 21 (for example, the maximum diameter when it varies depending on the position in the X direction) or the circle equivalent diameter may be, for example, 1 / 2 or less, 1 / 3 or less, or 1 / 4 or less of the length in the Z' direction of the pad portion 9a (the length when ignoring the existence of the third through hole 21. When it varies depending on the position in the X direction, for example, the minimum length of the area where the third through hole 21 and the position in the X direction overlap). Conversely, it may be 1 / 4 or more, 1 / 3 or more, or 1 / 2 or more. The above upper and lower limits may be arbitrarily combined so as not to cause a contradiction. In the above description, instead of the length in the Z' direction of the pad portion 9a, a length of 1 / 3 of the length in the Z' direction of the crystal element 1 or the fixing portion 15 may be used.

[0065] The diameter in the X direction of the third through hole 21 (for example, the maximum diameter when it varies depending on the position in the Z' direction) or the circle equivalent diameter may be, for example, 1 / 2 or less, 1 / 3 or less, or 1 / 4 or less, or conversely, 1 / 4 or more, 1 / 3 or more, or 1 / 2 or more, relative to the length in the X direction of the pad portion 9a (the length when the existence of the third through hole 21 is ignored. When it varies depending on the position in the Z' direction, for example, the minimum length of the area where the third through hole 21 and the position in the Z' direction overlap). The above upper and lower limits may be arbitrarily combined so as not to cause a contradiction. In the above description, instead of the length in the X direction of the pad portion 9a, the length obtained by subtracting the length in the X direction of the vibration portion 13 from the length in the X direction of the crystal element 1, the length in the X direction from the excitation electrode 7 to the first end portion 3a, or the length in the X direction of the fixing portion 15 may be used.

[0066] (1.2. Conductive Pattern) The material of the conductor pattern 5 may be, for example, a metal. The conductor pattern 5 may be composed of one metal layer made of a single material, or may be composed of a plurality of metal layers made of different materials stacked together. Examples of the material of the metal layer include nickel, chromium, nichrome, titanium, gold, silver, or alloys containing these. The conductor pattern 5 may be composed of, for example, the entire region (in other words, the area) of the conductor pattern 5 made of the same material, or some regions may be composed of different materials.

[0067] (1.2.1. Excitation electrode) The pair of excitation electrodes 7 are located on both main surfaces of the vibration section 13 to apply a voltage to the vibration section 13 as described above. The pair of excitation electrodes 7 are provided, for example, in positions, shapes, and sizes that overlap each other almost exactly in a planar perspective. However, there may be portions that do not overlap each other. The position, shape, size, etc. of the excitation electrodes 7 in a planar view may be set appropriately.

[0068] For example, the excitation electrode 7 is located in a central region of the vibration part 13. From another point of view, the excitation electrode 7 is located away from the outer edge of the vibration part 13. The center of the excitation electrode 7, for example, roughly coincides with the center of the vibration part 13 and / or its main surface in the Z' direction. In addition, the center of the excitation electrode 7 may be located on the +X side, may coincide with the center, or may be located on the -X side in the X direction with respect to the center of the vibration part 13.

[0069] Also, for example, the shape of the excitation electrode 7 may be similar to the shape of the vibration part 13, or may be different (as shown in the example). An example of the former is a mode in which the shape of the vibration part 13 is rectangular, while the shape of the excitation electrode 7 is rectangular having a long side parallel to the long side of the vibration part 13 (at least one of which may be square). An example of the latter is a mode in which the shape of the vibration part 13 is rectangular, while the shape of the excitation electrode 7 is circular, elliptical, or polygonal (excluding quadrangle), as shown in the example.

[0070] (1.2.2. Extraction electrode) Each extraction electrode 9 is extracted from the excitation electrode 7 toward the first end 3a. In this case, as can be understood from the illustrated example, the wiring portion 9b does not have to extend parallel to the direction from the excitation electrode 7 to the first end 3a (X direction). If the entire extraction electrode 9 is extracted toward the first end 3a side (+X side) with respect to the excitation electrode 7, the extraction electrode 9 may be expressed as being extracted toward the first end 3a side. Alternatively, if the entire or center of the pad portion 9a is located on the +X side of the excitation electrode 7 in the X direction, it may be expressed as above.

[0071] In each extraction electrode 9, the pad portion 9a overlaps at least the lower surface (the surface on the pad 111 side in FIG. 4; the same applies to the surfaces of other parts below) of the quartz crystal plate 3. That is, a pair of pad portions 9a of a pair of extraction electrodes 9 are arranged on the lower surface of the quartz crystal plate 3. In the illustrated example, each extraction electrode 9 also has a pad portion 9a on the upper surface of the quartz crystal plate 3 (the surface opposite to the pad 111; the same applies to the surfaces of other parts below). That is, each extraction electrode 9 has two pad portions 9a, and a pair of extraction electrodes 9 has a total of two pairs of pad portions 9a. This makes it possible, for example, for the quartz crystal element 1 to have either of the pair of main surfaces as the lower surface. Unlike the illustrated example, a pair of extraction electrodes 9 may have only a pair of pad portions 9a.

[0072] The pair of pads 9a on the lower surface (or upper surface) of the quartz crystal element 1 are aligned in the Z' direction. The pair of pads 9a on the lower surface (or upper surface) may be provided, for example, in positions, shapes, and sizes that are approximately line-symmetrical with respect to a center line CL that is parallel to the X-axis of the quartz crystal plate 3. The pair of pads 9a on the lower surface and the pair of pads 9a on the upper surface may have the same configuration.

[0073] In each extraction electrode 9, the pad portion 9a on the upper surface and the pad portion 9a on the lower surface are connected by a portion (reference numerals omitted) located on the side surface of each extraction electrode 9 facing the X direction and / or the side surface facing the Y direction of the quartz crystal plate 3. This connects the excitation electrode 7 on the upper surface (or the lower surface) and the pad portion 9a on the lower surface (or the upper surface). Unlike the illustrated example, in a mode in which the pad portion 9a on the upper surface is not provided, for example, the wiring portion 9b may be extended to the side surface facing the X direction and / or the side surface facing the Y direction of the quartz crystal plate 3 to connect the excitation electrode 7 on the upper surface and the pad portion 9a on the lower surface.

[0074] The specific position, shape, size, etc. of each pad portion 9a may be set appropriately. In the illustrated example, the pad portion 9a is located on one main surface of the quartz crystal plate 3, closer to the first end portion 3a (+X side) than the center of the main surface, and reaches the first end portion 3a and also reaches the edge portion on the +Z' side or -Z' side. The pad portion 9a also overlaps at least the fixed portion 15. In the illustrated example, the pad portion 9a overlaps not only the fixed portion 15 but also the intermediate portion 17 and further overlaps the vibration portion 13. Although not particularly illustrated, the pad portion 9a does not have to overlap the vibration portion 13 or the intermediate portion 17.

[0075] In the illustrated example, the pad portion 9a has a rectangular shape with sides parallel to the X direction and the Z' direction, and a notch 9c is formed in the pad portion 9a. Unlike the illustrated example, the pad portion 9a may have a shape without the notch 9c (e.g., rectangular). The length in the Z' direction of each pad portion 9a (e.g., maximum length) may be 1 / 3 or more (in the illustrated example) or less than 1 / 3 of the length in the Z' direction of the quartz crystal plate 3 or the fixing portion 15. The length in the X direction of the pad portion 9a (e.g., maximum length) may be 1 / 3 or more (in the illustrated example) or less than 1 / 3 of the length in the X direction of the quartz crystal plate 3.

[0076] The notch 9c is formed on the opposing edges of a pair of pad portions 9a that are spaced apart from each other in the Z' direction. The notch 9c is located, for example, entirely or at its center in a range of 2 / 3 or 1 / 2 or less of the length in the X direction of the pad portion 9a or the fixing portion 15 (ignoring the presence of the notch 9c; for example, the maximum length, or the length of the portion where the Z' direction position overlaps with the notch 9c) on the first end portion 3a side. By forming the notch 9c, the distance in the Z' direction between the pair of pad portions 9a is locally increased. The length in the Z' direction of the notch 9c (in another perspective, 1 / 2 the length of the increased distance between the pair of pad portions 9a) may be set appropriately. For example, the length of the notch 9c in the Z' direction may be 1 / 10 or more, 1 / 5 or more, or 1 / 4 or more of the length of the pad portion 9a in the Z' direction (e.g., the maximum length, or the length of the portion adjacent to the notch 9c in the X direction, or 1 / 3 of the length of the quartz crystal plate 3 in the Z' direction), or 1 / 2 or less, 1 / 3 or less, or 1 / 4 or less. The above lower and upper limits may be combined in any way so long as no contradiction occurs.

[0077] In each extraction electrode 9, the wiring portion 9b extends from the excitation electrode 7, for example, to reach the pad portion 9a on the surface (upper or lower surface) on which the excitation electrode 7 is located. In the illustrated example, as described above, the pad portion 9a overlaps not only the fixed portion 15 but also the intermediate portion 17 and the vibration portion 13, and thus the wiring portion 9b overlaps only the vibration portion 13 and does not overlap the intermediate portion 17 or the fixed portion 15. Unlike the illustrated example, in an embodiment in which the pad portion 9a does not overlap the vibration portion 13, the wiring portion 9b may overlap the intermediate portion 17 or the fixed portion 15.

[0078] The specific position, shape, size, etc. of the wiring portion 9b may be set as appropriate. In the illustrated example, the wiring portion 9b extends with a constant width obliquely in the X direction from the first end 3a side of the edge of the excitation electrode 7. Unlike the illustrated example, the wiring portion 9b may extend parallel to the X direction or may have a variable width. In an embodiment in which the excitation electrode 7 is rectangular, the wiring portion 9b may extend from the side of the excitation electrode 7 on the first end 3a side, or may extend from a corner. To be clear, the width (or length in the Z' direction) of the wiring portion 9b is narrower than the width (length in the Z' direction) of the pad portion 9a.

[0079] (1.3. Positional Relationship Between the Conductive Pattern and the Second Through Hole and the Third Through Hole) The second through hole 19 and the third through hole 21 overlap, for example, with the extraction electrode 9. As a result, these through holes contribute to electrical continuity between the front and rear of the quartz crystal plate 3. However, unlike the example shown in the figure, the second through hole 19 may not overlap with the extraction electrode 9 and may contribute only to improving the vibration characteristics. The third through hole 21 may also be provided so as not to overlap with the extraction electrode 9. In this case, the third through hole 21 may be regarded as a buffer section 11 depending on its position.

[0080] Specifically, for example, both ends of the second through hole 19 in the Z' direction overlap with both of the pair of extraction electrodes 9. Each of the pair of extraction electrodes 9 has a portion located on the inner surface of one end of the second through hole 19. As a result, the portions of each of the pair of extraction electrodes 9 located on the front and back of the quartz crystal plate 3 are electrically connected to each other. More specifically, in the illustrated example, the pair of pad portions 9a overlap the second through hole 19. On the inner surface of the second through hole 19, the pair of extraction electrodes 9 are separated from each other so as not to short-circuit each other. The overlapping length of each extraction electrode 9 and the second through hole 19 in the Z' direction, and the distance between the pair of extraction electrodes 9 in the second through hole 19, etc. may be set appropriately.

[0081] Moreover, each of the multiple (two in the illustrated example) third through holes 21 overlaps, for example, one of a pair of extraction electrodes 9. Each extraction electrode 9 has a portion located on the inner surface of one or more (one in the illustrated example) third through holes 21. As a result, the portions of each pair of extraction electrodes 9 located on the front and back of the quartz crystal plate 3 are electrically connected to each other. More specifically, in the illustrated example, the pad portion 9a overlaps at least one of the third through holes 21 in the plan view. The extraction electrode 9 overlaps, for example, the entire inner surface of the third through hole 21. Note that, unlike the illustrated example, the extraction electrode 9 may overlap a portion of the third through hole 21.

[0082] (1.4.Buffer) In this embodiment, as described above, the buffer section 11 is configured by a through hole (first through hole) that penetrates the quartz crystal plate 3 in the thickness direction. The buffer section 11 is located between a pair of extraction electrodes 9 (more specifically, for example, a pair of pad sections 9a). As a result, as described above, when distortion is applied to the quartz crystal plate 3 from the outside (for example, package 103) via the pair of extraction electrodes 9, this distortion is absorbed by the buffer section 11. As a result, for example, the vibration characteristics of the quartz crystal plate 3 are improved.

[0083] The second through hole 19, like the buffer section 11, is located between a pair of extraction electrodes 9 and can contribute to improving the characteristics of the vibration excited by the excitation electrode 7. However, the two can be distinguished from various viewpoints. For example, the buffer section 11 and the second through hole 19 differ in the specific manner of their action on the vibration excited by the excitation electrode 7. That is, the former mainly contributes to absorbing distortion, whereas the latter contributes to reducing the restriction of vibration. Due to such differences in intended action, the positions, shapes, and dimensions of the two may be different from each other. Note that, even if the main action and / or intended action are as described above, the second through hole 19 may contribute to absorbing distortion, and the buffer section 11 may contribute to reducing the restriction of vibration.

[0084] Only one buffer section 11 (through hole in this embodiment) may be provided (as shown in the example), or two or more may be provided. In the description of this embodiment and the second and third embodiments (FIGS. 5 and 6), the former is taken as an example, and in the description of other embodiments, the former may be used as a premise without special mention. The latter will be described in the description of a modified example (FIG. 7) described later.

[0085] In plan view, the buffer section 11 is, for example, away from a pair of extraction electrodes 9 (more specifically, a pair of pad sections 9a). That is, in plan view, a non-arrangement area of ​​the conductor pattern 5 is interposed between the buffer section 11 and the pair of extraction electrodes 9. From another perspective, the buffer section 11 does not contribute to electrical conduction between the front and back of the crystal element 1. However, unlike the illustrated example, the buffer section 11 may be adjacent to or overlap one or both of the pair of extraction electrodes 9. In this case, the inner surface of the buffer section 11 may or may not have a portion that conducts electrical conduction between the portions of each extraction electrode 9 located on the front and back of the crystal blank 3.

[0086] In the illustrated example, the edges of the pair of extraction electrodes 9 that face each other across the buffer section 11 in a plan view are cut out by a notch 9c. This facilitates the enlargement of the buffer section 11 in the Z' direction while separating the buffer section 11 from the pair of extraction electrodes 9. The buffer section 11 may be partially contained in the notch 9c (illustrated example), or may not be contained. In the former case, the overlap amount (length in the Z' direction) between the buffer section 11 and one extraction electrode 9 is arbitrary. For example, the overlap amount may be 1 / 10 or more or 1 / 5 or more of the length of the buffer section 11 in the Z' direction, and may be 1 / 3 or more or 1 / 2 or more of the length of one notch 9c in the Z' direction.

[0087] At least a part of the buffer section 11 is located on the fixed section 15. In the illustrated example, the entire buffer section 11 is located on the fixed section 15, and is away from the end of the fixed section 15 on the vibration section 13 side (the boundary between the fixed section 15 and the intermediate section 17) toward the first end section 3a. In this case, the position of the buffer section 11 in the X direction is arbitrary. For example, the entire or center of the buffer section 11 may be located within a range of 1 / 2 or 1 / 3 or less of the length of the pad section 9a or the fixed section 15 in the X direction (for example, the maximum length, or the length of the portion overlapping with the buffer section 11 or the portion closest to the buffer section 11 in the Z' direction) toward the first end section 3a. The center or a part of the buffer section 11 may be located on the center line CL (illustrated example), or may not be located there.

[0088] The distance (e.g., the shortest distance) between the buffer section 11 and the first end section 3a (more specifically, the side surface on the +X side of the quartz crystal plate 3) is arbitrary. For example, the distance may be 1 / 50 or more, 1 / 30 or more, or 1 / 10 or more of the length in the X direction of the fixing section 15 or the pad section 9a (e.g., the maximum length, or the length of the portion where the position in the Z' direction overlaps with the buffer section 11 or the portion closest to the buffer section 11), and may be 1 / 3 or less, 1 / 4 or less, 1 / 5 or less, or 1 / 10 or less. The above lower and upper limits may be combined arbitrarily as long as no contradiction occurs.

[0089] In the illustrated example, the shape of the buffer section 11 in plan view is an ellipse with the Z' direction as the major axis. Unlike the illustrated example, the shape of the buffer section 11 in plan view may be, for example, a polygonal shape (e.g., a rectangle), a circular shape, or a shape in which the sides of a polygon are arc-shaped and bulge outward. Furthermore, the shape of the buffer section 11 in plan view may not be the simple shape described above (a shape that forms the boundary of a convex set in mathematics), but may be a complex shape such as a T-shape. In addition, the shape of the buffer section 11 in plan view may be, contrary to the illustrated example, a length (e.g., maximum length) in the X direction that is greater than a length (e.g., maximum length) in the Z' direction. In this case, for example, when a distortion that bends the quartz crystal plate 3 to the +Y' side or -Y' side in the X direction is applied to the quartz crystal plate 3 from a pair of extraction electrodes 9, the effect of absorbing the distortion is improved.

[0090] The buffer section 11 is, for example, independent from the second through hole 19 and the third through hole 21 (not connected to the second through hole 19 and the third through hole 21). However, unlike the illustrated example, the buffer section 11 may be connected to the second through hole 19 and / or the third through hole 21. For example, the buffer section 11 may be formed into a slit shape that is long in the X direction and connected to the second through hole 19. In such a case, the buffer section 11, the second through hole 19, and the third through hole 21 may be rationally distinguished in light of their shapes and / or dimensions.

[0091] The shape and dimensions of the XZ' cross section of the buffer section 11 may be constant in the Y' direction (penetration direction) or may vary. An example of the latter is a mode in which a crystal plane inclined to the Y' axis appears on the inner surface of the buffer section 11. In this case, the position, shape, dimensions, etc. of the buffer section 11 described above or later may be, for example, those of the opening surface (third surface 25A or fourth surface 25B).

[0092] In the illustrated example, the maximum diameter, circle-equivalent diameter, and maximum length in the Z' direction of the buffer section 11 are smaller than the maximum length in the Z' direction of the second through hole 19. The maximum diameter, circle-equivalent diameter, and / or maximum length in the X direction of the buffer section 11 may be smaller, equal to, or larger than the length (width) in the X direction of the second through hole 19. The opening area of ​​the buffer section 11 may be smaller (in the illustrated example), equal to, or larger than the opening area of ​​the second through hole 19.

[0093] In the illustrated example, the shape and dimensions of the buffer section 11 are generally similar to those of the third through hole 21 in plan view. Unlike the illustrated example, the shape of the buffer section 11 may be different from that of the third through hole 21 in plan view. In addition, when the two shapes are similar or dissimilar, the buffer section 11 may be larger, equal, or smaller than the third through hole 21 in the X direction and / or Z' direction. Similarly, when the two shapes are similar or dissimilar, the opening area of ​​the buffer section 11 may be smaller, equal, or larger than the opening area of ​​the third through hole 21 (illustrated example).

[0094] As described above, the buffer section 11 may not overlap the extraction electrode 9 (as shown in the example), or may overlap the extraction electrode 9. As can be understood from this, the length of the buffer section 11 in the Z' direction (for example, the maximum length when it varies depending on the position in the X direction) may be smaller (as shown in the example), equal to, or larger than the distance (minimum or maximum value) in the Z' direction between a pair of extraction electrodes 9 (a pair of pad sections 9a). For example, the former may be 1 / 5 or more, 1 / 2 or more, 1 time or more, or 3 / 2 or more, or 3 times or less, 2 times or less, 1 time or less, 1 / 2 or less, or 1 / 3 or less, of the latter. The above lower limit and upper limit may be combined with any one other without causing any contradiction. In the above, 1 / 3 of the length of the quartz crystal plate 3 (fixing section 15) in the Z' direction may be used instead of the distance in the Z' direction between a pair of extraction electrodes 9 so as to avoid any contradiction.

[0095] The length of the buffer section 11 in the X direction (e.g., the maximum length when it varies depending on the position in the Z' direction) may be, for example, 1 / 10 or more, 1 / 5 or more, 1 / 3 or more, or 1 / 2 or more of the length of the pad section 9a or the fixing section 15 in the X direction (e.g., the maximum length, or the length of the portion where the position in the Z' direction overlaps with the buffer section 11 or the portion closest to the buffer section 11), and may be 1.2 times or less, 1 time or less, 4 / 5 or less, 2 / 3 or less, 1 / 2 or less, or 1 / 3 or less. The above lower limit and upper limit may be arbitrarily combined so as not to cause a contradiction. The above upper limit of 1.2 times or less or 1 time or less takes into consideration an embodiment in which the second through hole 19 is not provided or an embodiment in which the second through hole 19 and the buffer section 11 are connected, unlike the illustrated example.

[0096] (1.5. Manufacturing method of crystal element) The crystal element 1 may be manufactured by applying various known manufacturing methods. Although not specifically shown in the drawings, an example of such a method will be described below.

[0097] First, a wafer made of quartz crystal is prepared. The wafer is used to obtain a large number of quartz crystal blanks 3. Such a wafer is cut, for example, at the cutting angle of the AT cut plate described above, and is processed to a thickness equal to that of the fixing portion 15.

[0098] Next, etching masks are formed on both main surfaces of the wafer. These etching masks overlap, for example, the area that will become the quartz crystal plate 3 (the vibration portion 13, the intermediate portion 17, and the fixed portion 15) and the area that will become the frame-shaped portion (a discarded portion) that connects the multiple quartz crystal plates 3. In addition, these etching masks have openings formed in the areas that overlap the buffer portion 11, the second through hole 19, and the third through hole 21.

[0099] Then, the wafer is etched from both main surfaces through an etching mask. For example, the etching is wet etching in which the wafer is immersed in a chemical solution. As a result, the periphery of the region that will become the quartz crystal plate 3 is etched, forming the outer shape of the quartz crystal plate 3, and forming the buffer section 11, the second through hole 19, and the third through hole 21.

[0100] Next, new etching masks are formed on both main surfaces of the wafer. The new etching masks overlap the areas that will become the fixed portion 15 (third surface 25A or fourth surface 25B) (but do not overlap the areas that will become the vibration portion 13 and the intermediate portion 17). The new etching masks may be formed by removing a portion of the previous etching mask.

[0101] Then, the wafer is etched from both main surfaces through a new etching mask, so that the region that will become the vibration section 13 is thinner than the region that will become the fixed section 15. Also, due to the anisotropy of quartz with respect to etching, a crystal plane appears between the vibration section 13 and the fixed section 15, and an intermediate section 17 that is thicker toward the fixed section 15 is formed between the vibration section 13 and the fixed section 15.

[0102] The etching mask is then removed to form the conductor pattern 5. The conductor pattern 5 may be formed, for example, by depositing a metal film through a mask formed on the surface of the quartz crystal plate 3. Alternatively, the conductor pattern 5 may be formed by depositing a metal film over the entire surface or most of the quartz crystal plate 3, and then etching the metal film through a mask. The film may be formed by an appropriate method such as sputtering.

[0103] After the conductive pattern 5 is formed, the quartz crystal plate 3 is separated (diced) from the frame-shaped portion of the wafer by, for example, bending or cutting the connection portion with the frame-shaped portion. During and / or after singulation, the fixing portion 15 may be used to hold the quartz crystal element 1. For example, the fixing portion 15 may be held by suction, thereby holding the quartz crystal element 1 on a jig.

[0104] (2. Example of use of crystal element 1) Fig. 3 is a perspective view of a quartz crystal device 101 as an example of use of the quartz crystal element 1. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3. Note that while the quartz crystal device 101 may be oriented in either a vertical or horizontal direction, for convenience in the following description, the upper side of the paper in Figs. 3 and 4 may be referred to as "upper side" and terms such as "top surface" may be used.

[0105] The crystal device 101 is, for example, an electronic component that has a generally rectangular parallelepiped shape. The dimensions of the crystal device may be any appropriate size. For example, the length of the long or short side is 0.6 mm or more and 2.0 mm or less, and the thickness in the vertical direction is 0.2 mm or more and 1.5 mm or less. The crystal device 101 is, for example, surface-mounted with its bottom surface facing the top surface of a mounting base (e.g., a circuit board) (not shown).

[0106] The crystal device 101 is configured as, for example, an oscillator that contributes to the generation of an oscillation signal in which the signal strength (for example, voltage and / or current) oscillates at a certain frequency. The crystal device 101 includes, for example, a crystal element 1 that generates the vibration used to generate the oscillation signal, and a package 103 that packages the crystal element 1.

[0107] The package 103 has, for example, a base 107 that supports the crystal element 1, and a lid 109 that is bonded to the base 107 and seals the crystal element 1. The crystal element 1 is supported by being bonded to the base 107 by, for example, a conductive bonding material 105. The internal space of the package 103 is, for example, a vacuum or filled with an appropriate gas (for example, nitrogen).

[0108] The base 107 is shaped to have, for example, a recess for accommodating the crystal element 1. From another perspective, the base 107 has a flat substrate portion 107a and a frame portion 107b provided along the edge of the upper surface of the substrate portion 107a. The base 107 consisting of the substrate portion 107a and the frame portion 107b is made of an insulating material such as a ceramic material. The lid 109 is made of, for example, a metal, and is joined to the upper surface of the frame portion 107b by seam welding or the like.

[0109] The package 103 has conductors for electrically connecting the crystal element 1 and a mounting base (not shown) on which the crystal device 101 is mounted. For example, the package 103 has pads 111 for mounting the crystal element 1, external terminals 113 for mounting the crystal device 101 on a mounting base, and wiring conductors (not shown) for connecting the two.

[0110] The pads 111 are formed of a conductive layer located on the upper surface of the substrate portion 107a. The external terminals 113 are formed of a conductive layer located on the lower surface of the substrate portion 107a. The wiring conductors (not shown) are formed to include through conductors that vertically penetrate the substrate portion 107a. The material of these conductors is, for example, a metal.

[0111] The crystal element 1 is bonded to the pad 111 by the bonding material 105. As a result, the crystal element 1 is supported by the base 107 and is electrically connected to the package 103. More specifically, the crystal element 1 is bonded to the pad 111 at, for example, one end thereof and supported in a cantilever shape. The bonding material 105 is made of, for example, a conductive adhesive. The conductive adhesive is made of a thermosetting resin mixed with a metal filler.

[0112] The bonding material 105 may be located in the third through hole 21 (illustrated example), or may not be located therein. In the former case, the manner and amount of filling are arbitrary. For example, the bonding material 105 may be filled without gaps in the third through hole 21 from the lower end of the third through hole 21 to a predetermined height in the third through hole 21 (illustrated example), may be layered on the inner surface of the third through hole 21 to form a cavity, or may be positioned offset in either radial direction in the third through hole 21. In addition, the position of the upper end of the bonding material 105 in the third through hole 21 may be located in a range from the lower end of the third through hole 21 to the center in the depth direction of the third through hole 21, may be located between the center and the upper end of the third through hole 21 (illustrated example), or may be located above the upper end of the third through hole 21 (the bonding material 105 may include a portion located directly above the third through hole 21). If the bonding material 105 includes a portion located directly above the third through hole 21, this portion may or may not be connected to the portion of the bonding material 105 that wraps around the outer periphery of the quartz crystal element 1.

[0113] The external terminals 113 are joined, for example, by soldering to pads on a mounting substrate (not shown), so that the crystal device 101 is supported and electrically connected to the mounting substrate.

[0114] The quartz crystal element 1 may be used in various other ways in addition to the above-mentioned examples of use.

[0115] For example, a crystal device (piezoelectric device) including the crystal element 1 may be an oscillator having, in addition to the crystal element 1, an integrated circuit element (IC: Integrated Circuit) that applies a voltage to the crystal element 1 to generate an oscillation signal. Also, for example, the vibrator may have other electronic elements such as a thermistor in addition to the crystal element 1. Also, the piezoelectric device may be equipped with a thermostatic oven.

[0116] In the piezoelectric device, the structure of the package that packages the crystal element 1 may be appropriately configured. For example, the package may have an H-shaped cross section with recesses on the upper and lower surfaces. The package may also be configured with a substrate-like base body (a base body without a recess) and a cap-like lid body that covers the base body.

[0117] (3. Summary of the First Embodiment) As described above, in this embodiment, the quartz element 1 has a piezoelectric plate (quartz plate 3), a pair of excitation electrodes 7, and a pair of extraction electrodes 9. The quartz plate 3 extends in a first direction (X direction) and a second direction (Z' direction) perpendicular to the X direction, and has a first end 3a on one side (+X side) of the X direction. The pair of excitation electrodes 7 overlap the quartz plate 3. The pair of extraction electrodes 9 overlap the quartz plate 3 and are extracted from the pair of excitation electrodes 7 toward the first end 3a. The pair of extraction electrodes 9 also have a pair of pad portions 9a that are separated from each other in the Z' direction. The quartz plate 3 has a buffer portion 11 located between the pair of pad portions 9a.

[0118] In this case, for example, as described above, when distortion is applied to the crystal plate 3 from the outside (for example, package 103) via a pair of extraction electrodes 9, the distortion is easily absorbed by the deformation of the buffer section 11. As a result, for example, distortion transmitted to the region of the excitation electrode 7 (vibration section 13) is reduced, and the likelihood of the vibration characteristics of the crystal element 1 deteriorating is reduced. As a result, the electrical characteristics of the crystal element 1 are improved.

[0119] In addition, assuming a situation in which a relatively small constant stress is applied and a deformation corresponding to the magnitude of the stress occurs in the quartz crystal plate 3, the distortion of the quartz crystal plate 3 (and thus the region of the excitation electrode 7) will be reduced by increasing the rigidity of the quartz crystal plate 3 without providing the buffer section 11. However, in reality, for example, if the package 103 warps, the force applied from the package 103 to the quartz crystal plate 3 is relatively large, and it can be considered that a certain distortion is applied from the package 103 to the quartz crystal plate 3. Therefore, by providing the buffer section 11 with low rigidity to absorb the distortion as described above, the likelihood of the distortion being transmitted to the region of the excitation electrode 7 can be reduced.

[0120] The buffer section 11 may include a first through hole that passes through the quartz crystal plate 3 in the thickness direction.

[0121] In this case, for example, the buffer section 11 can be formed when forming the outer shape of the quartz crystal plate 3 by etching. Also, for example, since the buffer section 11 extends across the entire thickness of the quartz crystal plate 3, even if it is made small in plan view, it is easy to maintain its effect of reducing the rigidity of the quartz crystal plate 3 (the effect of absorbing distortion). In other words, it is easy to make the buffer section 11 small in plan view.

[0122] The buffer section 11 may be located away from the pair of extraction electrodes 9 (the pair of pad sections 9a).

[0123] In this case, for example, the bonding material 105 is less likely to penetrate into the buffer section 11. As a result, for example, the likelihood that the deformation of the buffer section 11 is hindered by the bonding material 105 is reduced. In addition, the fact that the buffer section 11 is located between the pair of extraction electrodes 9 and away from the pair of extraction electrodes 9 means that the size of the buffer section 11 in the Z' direction is relatively small. Since the buffer section 11 is small in the Z' direction, for example, it is easy to ensure the strength in the region of the extraction electrodes 9 (in other words, the fixing section 15) for supporting the crystal element 1 in a cantilever shape by the bonding material 105. On the other hand, even if the buffer section 11 is small in the Z' direction, the function of allowing the relative movement of the pair of extraction electrodes 9 (absorbing distortion) can be maintained.

[0124] The size of the buffer section 11 in the Z' direction is an example of a difference between the buffer section 11 and the second through hole 19. As described above, the second through hole 19 is intended to reduce the area connecting the region of the excitation electrode 7 (in other words, the vibration section 13) and the region of the pair of extraction electrodes 9 (fixed section 15) and to reduce the likelihood that the vibration in the former region is restricted by the latter region. Therefore, in contrast to the buffer section 11, the second through hole 19 is made relatively large in the Z' direction and further overlaps with the pair of extraction electrodes 9.

[0125] However, as already mentioned, unlike the above description, the buffer section 11 may be adjacent to or overlap a pair of extraction electrodes 9. In other words, the buffer section 11 may be relatively large in the Z' direction. In this case, for example, the buffer section 11 can be used as a portion for releasing excess bonding material 105. Also, the buffer section 11 may be used for electrical conduction between the front and back, similar to the second through hole 19.

[0126] The quartz crystal plate 3 may have a vibrating section 13 on which a pair of excitation electrodes 7 overlap, and a fixed section 15 on which a pair of extraction electrodes 9 (pad sections 9a) overlap and which is thicker than the vibrating section 13. At least a portion of the buffer section 11 may be located on the fixed section 15.

[0127] In this case, for example, the quartz crystal plate 3 can ensure strength by the fixed portion 15, which is thicker than the vibrating portion 13. However, this makes it difficult for the fixed portion 15 to absorb distortion. In the quartz crystal plate 3 configured in this way, the buffer portion 11 is provided in the fixed portion 15, so that the buffer portion 11 can effectively absorb distortion.

[0128] The position of the buffer section 11 is an example of a difference between the buffer section 11 and the second through hole 19. As described above, the second through hole 19 is intended to reduce the area connecting the vibrating section 13 and the fixed section 15, thereby reducing the likelihood that the vibration in the vibrating section 13 will be restricted by the fixed section 15. Therefore, unlike the buffer section 11, the second through hole 19 is located between the vibrating section 13 and the fixed section 15.

[0129] The buffer section 11 may be located away from the end of the fixed section 15 on the vibrating section 13 side. More specifically, for example, the buffer section 11 may be located closer to the first end 3a side than the center of the fixed section 15.

[0130] In this case, for example, it is expected that the buffer section 11 located on the first end 3a side of the fixed section 15 will absorb the distortion applied to the first end 3a side, and that the portion of the fixed section 15 located on the vibrating section 13 side will reduce distortion due to the stress transmitted from the buffer section 11 side to the vibrating section 13 side. As will be understood from the above explanation, the position of such buffer section 11 is one example of the difference between the buffer section 11 and the second through hole 19.

[0131] The maximum length of the buffer section 11 in the first direction (X direction) may be equal to or less than half the length of the fixed section 15 in the X direction.

[0132] In this case, for example, it is easy to ensure the strength of the fixed part 15. Also, for example, when the buffer part 11 is located closer to the first end part 3a side than the center of the fixed part 15 as described above, it is expected that the buffer part 11 will absorb the distortion while reducing the distortion caused by the stress transmitted from the buffer part 11 side to the vibrating part 13 side.

[0133] The quartz crystal plate 3 may further include a second through hole 19 between the pair of excitation electrodes 7 and the buffer portion 11, which passes through the quartz crystal plate 3 in the thickness direction.

[0134] In this case, for example, while the buffer section 11 absorbs distortion, the second through hole 19 can reduce the likelihood that vibration in the region of the excitation electrode 7 (vibration section 13) is restricted by the region of the extraction electrode 9 (fixed section 15). As a result, vibration characteristics in the region of the excitation electrode 7 are improved. Also, for example, a beam-shaped portion is formed between the second through hole 19 and the buffer section 11, and the rigidity of the region of the buffer section 11 on the excitation electrode 7 side is reduced compared to a mode in which the second through hole 19 is not provided (this mode is also included in the technology according to the present disclosure), so that an improvement in the function of the buffer section 11 is expected.

[0135] In a plan view, the area of ​​the buffer section 11 may be smaller than the area of ​​the second through hole 19.

[0136] In this case, for example, it is easy to ensure the strength of the fixed portion 15. In addition, it is also easy to ensure the area of ​​the pair of extraction electrodes 9 located on both sides of the buffer section 11 in a plan view.

[0137] The quartz crystal plate 3 may further include a pair of third through holes 21 that penetrate the quartz crystal plate 3 in the thickness direction at positions that overlap the pair of extraction electrodes 9 in a plan view.

[0138] In this case, for example, the third through hole 21 can facilitate electrical continuity between the front and rear of the crystal element 1. Furthermore, depending on the configuration of the conductor pattern 5 and the bonding material 105, etc., a beam-shaped portion is formed between the third through hole 21 and the buffer section 11, and the rigidity of the region of the buffer section 11 on the extraction electrode 9 side is reduced compared to a configuration in which the third through hole 21 is not provided (this configuration is also included in the technology according to the present disclosure), and therefore an improvement in the function of the buffer section 11 is expected.

[0139] In a plan view, the center of the buffer section 11 may be located on a center line CL parallel to the X direction of the quartz crystal plate 3. The pair of third through holes 21 may be located line-symmetrically with respect to the center line CL.

[0140] In this case, for example, it is easy to make the rigidity of the buffer section 11 equal on both sides in the Z' direction. As a result, for example, when a distortion is applied to a pair of extraction electrodes 9, the probability that the distortion is biased toward the +Z' side or the -Z' side and transmitted to the region of the excitation electrode 7 is reduced. As a result, the probability that unintended peculiar vibration occurs is reduced, and thus the probability that the electrical characteristics of the crystal element 1 are degraded is reduced.

[0141] The piezoelectric device (crystal device 101) according to this embodiment includes the crystal element 1 as described above, and a package 103 in which the crystal element 1 is mounted.

[0142] Such a crystal device 101 can obtain the above-mentioned effects of the crystal element 1 according to this embodiment. For example, when the crystal element 1 is distorted due to warping of the package 103, the distortion can be absorbed by the buffer section 11 as described above.

[0143] The crystal device 101 may further include a conductive bonding material 105 that bonds the crystal element 1 to the package 103. The bonding material 105 may have a portion located inside the pair of third through holes 21.

[0144] In this case, for example, the bonding area between the bonding material 105 and the pair of extraction electrodes 9 can be increased to improve the reliability of the conduction between the crystal element 1 and the package 103. In addition, the excess bonding material 105 enters the third through hole 21 overlapping the extraction electrode 9 in preference to the buffer section 11 located between the extraction electrodes 9. That is, the probability that the bonding material 105 enters the buffer section 11 is reduced. As a result, for example, as described above, the probability that the deformation of the buffer section 11 is hindered by the bonding material 105 is reduced. In addition, for example, when the pair of third through holes 21 are arranged symmetrically with respect to the buffer section 11, the stress balance due to the hardening shrinkage of the bonding material 105 in the pair of third through holes 21 is likely to be uniform.

[0145] The shape of the buffer section 11 in a plan view may be a circle, an ellipse, or a polygon having rounded corners.

[0146] In this case, for example, the probability of stress concentration occurring in the buffer section 11 is reduced. In turn, the probability of damage to the quartz crystal plate 3 occurring in the buffer section 11 (and its surroundings) is reduced.

[0147] <Second embodiment> 5 is a perspective view of the quartz crystal element 201 according to the second embodiment, with a portion of the quartz crystal element 201 cut away. This view corresponds to FIG. 2 of the first embodiment. The perspective view of the quartz crystal element 201 in an uncut state is similar to FIG.

[0148] The quartz crystal element 201 differs from the quartz crystal element 1 of the first embodiment only in that the buffer section 211 of the quartz crystal blank 203 is constituted by a recess. In the illustrated example, recesses are formed on both main surfaces of the quartz crystal blank 203, for a total of two recesses. However, the recesses may be formed on only one of the main surfaces. Each of the two recesses may be regarded as the buffer section 211, or the area of ​​the quartz crystal blank 3 that includes the two recesses may be regarded as the buffer section 211. In the description of this embodiment, the former interpretation may be used for convenience.

[0149] The positions (excluding the positions in the Y' direction), shapes and dimensions of the two buffer sections 211 (recesses) are, for example, identical to each other (excluding the influence of crystal planes). However, the two may be different. In any case, the description of the position, shape, dimensions, etc. of the buffer section 11 (first through hole) in the first embodiment may be applied to the buffer section 211, except for the dimensions in the Y' direction.

[0150] The depth of the buffer section 211 is arbitrary. For example, the depth may be equal to the difference in height between the first surface 23A of the vibrating section 13 and the third surface 25A of the fixed section 15. From another perspective, the thickness of the portion of the quartz crystal plate 3 between the two buffer sections 211 may be equal to the thickness of the vibrating section 13. However, unlike the above description, the depth of the buffer section 211 may be smaller or larger than the difference in height.

[0151] The manufacturing method of the crystal element 201 may be the same as the manufacturing method of the crystal element 1, except for the method of forming the buffer section 211. In the manufacturing method of the crystal element 201, for example, an opening overlapping a region that will become the buffer section 211 is formed in an etching mask that is placed on the fixed section 15 in order to perform etching to thin the vibration section 13. As a result, a part of the main surface of the fixed section 15 is etched to form the buffer section 211.

[0152] When the buffer section 211 is formed as described above, for example, the depth (maximum depth) of the buffer section 211 is equivalent to the difference in height between the first surface 23A of the vibrating section 13 and the third surface 25A of the fixed section 15. However, due to the anisotropy of quartz crystal with respect to etching, the depth of the buffer section 211 may not reach the difference in height between the first surface 23A and the third surface 25A. From another perspective, the inner surface of the buffer section 211 may be composed only of inclined surfaces (crystal surfaces from another perspective) and may not include a bottom surface that is approximately perpendicular to the Y' axis.

[0153] Similarly to the buffer section 11 of the first embodiment, the buffer section 211 may be formed when etching the outer shape of the quartz crystal plate 203. In this case, for example, depending on the etching conditions, the diameter of the opening of the etching mask that overlaps with the area that will become the buffer section 211 is reduced. Then, the buffer section 211 made of a recess is formed by stopping the etching due to the anisotropy of the quartz crystal with respect to the etching.

[0154] The buffer section 211 does not have to be formed at the same time as the vibrating section 13 (or the outer shape of the quartz crystal plate 203) as described above. For example, it may be formed before the etching that forms the outer shape of the quartz crystal plate 203, or it may be formed after the etching that forms the outer shape and before the etching that thins the vibrating section 13, or it may be formed after the etching that thins the vibrating section 13. The buffer section 211 may be formed by mechanical processing rather than etching (this also applies to the buffer sections of other embodiments).

[0155] As described above, in this embodiment as well, the quartz crystal plate 203 has a buffer section 211 located between the pair of extraction electrodes 9. Therefore, the same effects as in the first embodiment are achieved. For example, when a distortion is applied from the package 103 via the pair of extraction electrodes 9, the distortion can be absorbed by the buffer section 211. As a result, the electrical characteristics of the quartz crystal element 201 are improved.

[0156] As can be seen from this embodiment, the buffer section 211 may include a recess that thins the quartz crystal plate 203 .

[0157] In this case, for example, when quartz crystal plate 203 has regions of different thicknesses (vibrating portion 13 and fixed portion 15), buffer portion 211 can be formed when thinning vibrating portion 13. Also, compared to buffer portion 11 consisting of a through hole, for example, this is advantageous when it is desired to ensure the strength of fixed portion 15 while obtaining the distortion absorption effect by buffer portion 211.

[0158] <Third embodiment> 6 is a perspective view of a crystal element 301 according to the third embodiment. This figure corresponds to FIG. 1 of the first embodiment.

[0159] The quartz crystal element 301 differs from the quartz crystal element 1 of the first embodiment only in that the buffer portion 311 of the quartz crystal blank 303 is configured by a notch. The notch as the buffer portion 311 cuts out the first end portion 3a (edge ​​portion) in a plan view. The notch can be considered as a type of through hole. However, in this disclosure, for the sake of convenience, in order to distinguish between a notch and a non-notch, a through hole refers to one in which the first end portion 3a is not cut out.

[0160] The description of the position, shape, dimensions, etc. of the buffer section 11 (first through hole) in the first embodiment may be applied to the buffer section 311. In this case, with respect to the shape of the buffer section 311 in a plan view, the shape of the edge of the buffer section 311 on the first end 3a side may be substituted by the shape of the first end 3a when not cut out (a virtual line extending the side surface facing the +X side of the quartz crystal plate 3 in the Z' direction to the position of the notch). In addition, the position of the buffer section 311 may be applied to the previously described position of the buffer section 11 as is, unless a contradiction occurs, or may be applied so that the buffer section 311 shifts to the +X side due to the distance (already described) between the buffer section 11 and the first end 3a. Similarly, the size of the buffer section 311 in the X direction may be applied to the previously described size of the buffer section 11 as is, unless a contradiction occurs, or may be applied so that the buffer section 311 expands to the +X side due to the distance between the buffer section 11 and the first end 3a.

[0161] The manufacturing method of the quartz crystal element 301 may be generally similar to the manufacturing method of the quartz crystal element 1 according to the first embodiment. However, in the etching mask for forming the outer shape of the quartz crystal blank 303, the portion overlapping the region that will become the buffer section 311 is not a closed opening in a plan view, but a notch. This forms the buffer section 311 consisting of a notch.

[0162] As described above, in this embodiment as well, the quartz crystal plate 303 has a buffer section 311 located between the pair of extraction electrodes 9. Therefore, the same effects as in the first embodiment are achieved. For example, when a distortion is applied from the package 103 via the pair of extraction electrodes 9, the distortion can be absorbed by the buffer section 311. As a result, the electrical characteristics of the quartz crystal element 301 are improved.

[0163] As can be seen from this embodiment, the buffer portion 311 may include a notch that cuts out the first end portion 3a of the quartz crystal plate 303 in a plan view.

[0164] In this case, for example, similar to the buffer section 11 made of a through hole, the buffer section 311 can be formed when etching the outer shape of the quartz crystal plate 303. Also, for example, the effect of absorbing distortion is improved compared to the buffer section 11 made of a through hole. From the viewpoint of ensuring the strength of the fixing section 15 while obtaining the effect of absorbing distortion, the buffer section 11 made of a through hole is advantageous.

[0165] <Modification> Various modified examples of the quartz crystal element will be described below. The buffer section in the modified examples described below may be any of the buffer sections of the first to third embodiments. However, for convenience, the buffer section 11 of the first embodiment will be basically taken as an example below. As long as no contradiction occurs, the term buffer section 11 may be replaced with the term buffer section 211 or the term buffer section 311. The following description will be generally given in the following order. Modifications regarding the number of buffer sections Modifications regarding the position of the fixing part -Modifications regarding the thickness of the fixing part

[0166] (Modification of the number of buffer sections) FIG. 7 is a plan view showing a quartz crystal element 401 (quartz crystal blank 403) according to a modified example.

[0167] As shown in this figure, two or more buffer sections 11 may be provided. When two or more buffer sections 11 are provided, the shapes and / or dimensions may be the same as each other (as in the illustrated example) or may be different from each other. Although not particularly illustrated, two or more of the buffer sections 11, 211, and 311 may be combined to provide two or more buffer sections. In any case, the above-mentioned description of the shape and dimensions of the buffer section 11 may be applied to the shape and dimensions of two or more buffer sections 11, unless a contradiction occurs. When applying the dimensions, the above-mentioned dimensions may be applied as they are, or the dimensions obtained by dividing the dimensions in a predetermined direction by the number of buffer sections 11 arranged in the predetermined direction may be applied, unless a contradiction occurs.

[0168] The two or more buffer sections 11 may be arranged arbitrarily. For example, some or all of the two or more buffer sections 11 may be aligned in the X direction, may be aligned in the Z' direction, may be aligned in a direction inclined to the above-mentioned direction, or may be arranged in such a manner that such distinction is impossible. The two or more buffer sections 11 may be arranged in a single row, or may be arranged in two or more rows. The two or more buffer sections 11 may be arranged symmetrically or asymmetrically with respect to the center line CL (see FIG. 1).

[0169] As described above, two or more buffer sections 11 may be regarded as a whole as the buffer section 411. When the center of the buffer section is located on the center line CL, this may include not only an embodiment in which the center of the buffer section 11 is located on the center line CL, but also an embodiment in which the center of the buffer section 411 is located on the center line CL.

[0170] Here, the second through hole 19 is shown, but the third through hole 21 is not shown, but the presence or absence of these through holes is optional. Similarly, in Fig. 8(a) and Fig. 8(b) and the like described later, the presence or absence of the second through hole 19 and the third through hole 21 is optional.

[0171] In an embodiment in which two or more buffer sections 11 are provided, for example, compared to an embodiment in which only one buffer section 11 is provided with an area equivalent to the total area of ​​the two or more buffer sections 11, it is possible to obtain the effect of absorbing distortion while reducing the likelihood of localized reduction in the strength of the fixed section 15. On the other hand, in the latter embodiment, for example, since the diameter of one buffer section 11 is large, it is possible to reduce the effect of the anisotropy of the quartz crystal on etching. For example, it is easy to reduce the inclined surface of the inner surface, and also easy to form a through hole.

[0172] When two or more buffer sections 11 are provided at different positions in the opposing direction (Z' direction) of a pair of extraction electrodes 9 in a plan view (for example, lined up in the Z' direction), even if the bonding material 105 bonded to one extraction electrode 9 enters the buffer section 11 close to that one extraction electrode 9, there is a low probability of short-circuiting with the other extraction electrodes 9. Therefore, for example, by bringing the buffer section 11 close to the extraction electrode 9, the buffer section 11 can be easily used as a place for excess bonding material 105 to escape.

[0173] (Modifications related to the position of the fixing part) Figures 8(a) and 8(b) are plan views of a quartz crystal plate according to a modified example. In the embodiment, the fixing portion 15 is shaped to follow one side of the rectangular vibrating portion 13. However, the fixing portion may follow two or more sides of the vibrating portion. The quartz crystal plate in Figures 8(a) and 8(b) has such a fixing portion that extends over two or more sides. Specifically, this is as follows.

[0174] The quartz crystal element 501 (quartz crystal blank 503) shown in FIG. 8(a) has a fixed portion 515 (and an intermediate portion 517) along two sides of the vibrating portion 13. In other words, the fixed portion 515 is formed in an L shape. The fixed portion 515 may not be considered to be configured in an L shape, but may be considered to be provided with a total of two linear fixed portions 515. And, in the same manner as in the embodiment, a pair of extraction electrodes 9 are extracted from the portion of the fixed portion 515 along one side of the vibrating portion 13, and the buffer portion 11 is positioned therebetween.

[0175] The quartz crystal element 601 (quartz crystal blank 603) shown in FIG. 8(b) has a fixed portion 615 (and an intermediate portion 617) along three sides of the vibrating portion 13. In other words, the fixed portion 615 is formed in a U-shape. The fixed portion 615 may not be considered to be configured in a U-shape, but may be considered to be provided with a total of three linear fixed portions 615. And, in the same manner as in the embodiment, a pair of extraction electrodes 9 are extracted from the portion of the fixed portion 615 along one side of the vibrating portion 13, and the buffer portion 11 is positioned therebetween.

[0176] Although not particularly shown, fixed portions may be provided along the four sides of the vibrating portion 13. A pair of extraction electrodes 9 may be drawn out from a portion of the fixed portion along one side of the vibrating portion 13, as in the embodiment, and a buffer portion 11 may be provided therebetween. In the description of the relative positions of the fixed portion 15 and other components (e.g., the buffer portion 11) in the embodiment, the term fixed portion 15 may be replaced with the term a portion of the fixed portions 515, 615, etc. along one side of the vibrating portion 13 (the entire portion or a portion having the same length as the length of the above-mentioned one side).

[0177] (Modifications related to thickness of fixing part) FIG. 9(a) is a cross-sectional view showing the configuration of a quartz crystal element 701 according to a modified example, and corresponds to a part of FIG.

[0178] In the crystal element 701, the fixed portion 715 (and the intermediate portion 717) is higher than the vibrating portion 13 only on one side (the lower portion in the figure) in the thickness direction of the crystal element 503. Although not shown here, a buffer portion is formed in the fixed portion 715 as in the embodiment. In this modification, the first conductor pattern 505A and the first conductor pattern 505B are not rotationally symmetrical by 180° with respect to the center line CL (see FIG. 1), for example. For example, the extraction electrode 509 may have a pad portion 9a only on the lower surface.

[0179] FIG. 9(b) is a cross-sectional view showing the configuration of a crystal element 801 according to a modified example, and corresponds to a part of FIG.

[0180] The quartz crystal plate 803 of the quartz crystal element 801 has a uniform thickness throughout. In other words, the quartz crystal plate 803 does not have a vibrating portion and a fixed portion that have different thicknesses. Although not shown here, a buffer portion is formed between a pair of extraction electrodes 9, as in the embodiment.

[0181] The technology according to the present disclosure is not limited to the above-described embodiment and modifications, and may be implemented in various forms.

[0182] The above-mentioned embodiment and various modified examples may be appropriately combined. For example, the configuration in which two or more buffer parts are provided as shown in Fig. 7 may be applied to the modified examples related to the fixed part as shown in Fig. 8(a) to Fig. 9(b). Also, the configuration in which the fixed part is higher only on one side in the thickness direction relative to the vibrating part as shown in Fig. 9(a) may be applied to the configuration in which the fixed part is provided across two or more sides as shown in Fig. 8(a) and Fig. 8(b).

[0183] The piezoelectric body is not limited to quartz. For example, the piezoelectric body may be other single crystals or may be made of polycrystals (for example, ceramics). The piezoelectric body is not limited to one that uses the fundamental vibration of thickness shear vibration, but may use other vibration modes or overtone vibration. Furthermore, the piezoelectric body may use elastic waves excited by an excitation electrode formed only on one of the main surfaces. The cut of the quartz blank that uses thickness shear vibration is not limited to AT cut. For example, it may be BT cut. The quartz blank is not limited to one made of quartz only, but also includes one made of a material in which a dopant made of metal or the like is injected into quartz.

[0184] From the present disclosure, it is possible to extract a piezoelectric vibration element in which it is not required that the buffer section be separated from the pair of extraction electrodes (the buffer section overlaps or is adjacent to both or one of the pair of extraction electrodes). The piezoelectric vibration element may be characterized in that the buffer section is located on the fixed section away from the end of the fixed section on the vibration section side, that it has a second through hole or a third through hole, that two or more buffer sections are provided, or that the buffer section is a recess that thins the crystal element, for example. [Explanation of symbols]

[0185] 1...quartz crystal element (piezoelectric vibration element), 3...quartz crystal blank (piezoelectric blank), 3a...first end (of piezoelectric blank), 7...excitation electrode, 9...extraction electrode, 11...buffer portion (first through hole), 13...vibration portion, 15...fixed portion, 101...quartz crystal device (piezoelectric device), 211...buffer portion (recess), 311...buffer portion (notch).

Claims

1. a piezoelectric plate extending in a first direction and a second direction perpendicular to the first direction and having a first end on one side of the first direction; A pair of excitation electrodes overlapping the piezoelectric plate; a pair of extraction electrodes overlapping the piezoelectric plate and extending from the pair of excitation electrodes toward the first end portion; It has The pair of extraction electrodes are a pair of pad portions spaced apart from each other in the second direction; a pair of wiring portions respectively connecting the pair of excitation electrodes and the pair of pad portions, each of the pair of pad portions has a side along the second direction on a side of the excitation electrode in the first direction, and only a portion of the side is connected to the wiring portion; The piezoelectric plate has a buffer portion, The buffer portion includes at least one of a first through hole penetrating the piezoelectric plate in the thickness direction and a recess that thins the piezoelectric plate, and is located between the pair of pad portions and spaced apart from the pair of pad portions, and the entire buffer portion is located closer to the first end portion than the side, but is spaced apart from the first end portion. Piezoelectric vibration element.

2. The piezoelectric blank is an AT-cut quartz crystal blank, and the first direction is an X-axis direction. The piezoelectric vibration element according to claim 1 .

3. The piezoelectric plate is a vibration section in which the pair of excitation electrodes overlap; The pair of pad portions overlap each other, and the pair of pad portions have a fixed portion that is thicker than the vibration portion. At least a portion of the buffer portion is located on the fixed portion. The piezoelectric vibration element according to claim 1 .

4. The buffer portion is spaced apart from the end portion of the fixed portion on the side of the vibrating portion. The piezoelectric vibration element according to claim 3 .

5. The piezoelectric plate further has a second through hole penetrating the piezoelectric plate in a thickness direction between the pair of excitation electrodes and the buffer portion. The piezoelectric vibration element according to any one of claims 1 to 4.

6. The piezoelectric plate further has a pair of third through holes penetrating the piezoelectric plate in a thickness direction at positions overlapping the pair of pad portions in a plan view. The piezoelectric vibration element according to any one of claims 1 to 5.

7. In a plan view, a center of the buffer portion is located on a center line of the piezoelectric plate that is parallel to the first direction, and the pair of third through holes are located line-symmetrically with respect to the center line. The piezoelectric vibration element according to claim 6 .

8. The pair of pad portions have edges that face each other across the buffer portion in a plan view and are cut out. The piezoelectric vibration element according to any one of claims 1 to 7.

9. The piezoelectric vibration element according to any one of claims 1 to 8, a package in which the piezoelectric vibration element is mounted; A piezoelectric device having a

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