Piezoelectric vibration element and piezoelectric device

Abstract

This piezoelectric vibration element comprises: a vibrating piece that has a vibrating section and a thick section and is rectangular in plan view; and a metal pattern that is located in the thick section. The thick section is located along at least two sides of the vibrating piece. The metal pattern comprises a first metal pattern that is located on a first surface and a second metal pattern that is located on a second surface and is not electrically continuous with any conductor other than the metal pattern. The first metal pattern and the second metal pattern have portions that overlap one another in plan view. The first metal pattern has: a first side that is perpendicular to a first direction; and a second side that is perpendicular to a second direction that is perpendicular to the first direction in plan view. The second metal pattern has: a third side that is perpendicular to the first direction; and a fourth side that is perpendicular to the second direction. A region between the first side and the third side and a region between the second side and the fourth side are outside the first metal pattern and the second metal pattern, respectively.

Description

Piezoelectric vibration element and piezoelectric device

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

[0002] Conventionally, there are vibration elements such as quartz crystal vibration elements that resonate when a voltage corresponding to the resonant frequency is applied. As vibration elements become higher in frequency and smaller in size, there is a growing demand for improved and more stable electrical characteristics. In Japanese Patent Application Laid-Open No. 2020-174304, the planar positions of the excitation electrodes located on both sides of the quartz crystal blank are appropriately shifted to more effectively contain vibration energy and reduce the CI value.

[0003] One aspect of the present disclosure is: (1) a resonator element having a rectangular shape in plan view, the resonator element having a vibrating portion and a thick portion that is thicker than the vibrating portion, the resonator element having a side parallel to a first direction and a side parallel to a second direction perpendicular to the first direction; and a metal pattern located on the thick portion, the thick portion being located along at least two sides of the resonator element, the metal pattern having a first metal pattern located on the thick portion of a first surface of the resonator element in plan view, and a second metal pattern located on the thick portion of a second surface opposite to the first surface, the metal pattern not being electrically connected to any conductor other than the metal pattern, (2) A piezoelectric vibration element according to (1), wherein the first metal pattern and the second metal pattern have overlapping portions in a planar view, the first metal pattern has a first side perpendicular to the first direction and a second side perpendicular to a second direction perpendicular to the first direction in a planar view, the second metal pattern has a third side perpendicular to the first direction and a fourth side perpendicular to the second direction, the region between the first side and the third side being outside the first metal pattern or the second metal pattern, and the region between the second side and the fourth side being outside the first metal pattern or the second metal pattern. (3) A piezoelectric vibration element according to (1) or (2), wherein the first metal pattern and the second metal pattern are located at corners of the vibration element in a planar view. (4) A piezoelectric vibration element according to any one of (1) to (3), wherein a resonance frequency is 75 MHz or higher. (5) The piezoelectric vibration element according to any one of (1) to (4), wherein the vibration piece is a quartz crystal piece, the first direction is along an X-axis direction of the quartz crystal piece, and the second direction is along a Z'-axis direction of the quartz crystal piece. (6) A piezoelectric device comprising: the piezoelectric vibration element according to any one of (1) to (5), and a package that houses the piezoelectric vibration element.

[0004] 1 is an overall perspective view of a piezoelectric vibrator; FIG. 2 is a cross-sectional view of a piezoelectric vibrator; FIG. 3 is a perspective view of a first surface side of a piezoelectric vibration element; FIG. 4 is a perspective view of a second surface side of a piezoelectric vibration element; FIG. 5 is an example of a plan view enlarging the vicinity of a metal pattern; and FIG. 6 is an example of a plan view enlarging the vicinity of a metal pattern.

[0005] Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is an overall perspective view of a piezoelectric vibrator 1 according to this embodiment. This FIG. 1 shows a state in which a lid 30 is removed. Note that in the drawings of this disclosure, the ratio of height in the Z-axis direction to size in the XY-axis plane perpendicular to the Z-axis is for illustrative purposes only and does not necessarily reflect actual values. The piezoelectric vibrator 1, which is a piezoelectric device according to this disclosure, includes a package 10, a piezoelectric vibration element 20, and a lid 30.

[0006] The package 10 is a housing made of, for example, a ceramic material, a semiconductor material, a glass material, or a combination of these. Conductor signal lines are provided inside and on the surface of the above-mentioned material of the package 10. The signal lines include lines related to power supply and lines related to grounding. The signal lines may be made of, for example, molybdenum, copper, silver, tungsten, or the like. Nickel plating, gold plating, or the like may be laminated on the surface of some or all of the signal lines. The package 10 has a recess 10a that opens to the top surface, which is the +Z side surface. The piezoelectric vibration element 20 is housed in the recess 10a.

[0007] The piezoelectric vibration element 20 of this embodiment is a quartz vibration element. The piezoelectric vibration element 20 is located inside the recess 10a. The piezoelectric vibration element 20 is rectangular in plan view, but the corners may be rounded or chamfered. Depending on the shape of the piezoelectric vibration element 20, the recess 10a may also be rectangular in plan view. The X-axis direction in each figure is equal to the X-axis direction of the quartz vibration element and corresponds to the first direction of the present disclosure. The Y-axis direction in each figure represents the Z'-axis direction of the quartz vibration element and corresponds to the second direction of the present disclosure. The longitudinal direction of the piezoelectric vibration element 20 is parallel to the X-axis, and the direction perpendicular to the longitudinal direction is parallel to the Y-axis.

[0008] The lid 30 is joined to the periphery of the opening of the package 10, i.e., to the upper end of the sidewall surrounding the recess 10a in a plan view seen from the +Z side, thereby sealing the recess 10a. The lid 30 is a flat plate of a metal conductor, and may be, for example, a metal containing iron, copper, nickel, cobalt, molybdenum, or tungsten, or an alloy thereof, such as Kovar. The lid 30 may be joined to the package 10, for example, by a brazing material. A frame-shaped metallization layer may be located between the upper end of the package 10 and the lid 30. The metallization layer may be a plated layer or a conductor layer that is applied and baked.

[0009] Fig. 2 is a cross-sectional view of the piezoelectric vibrator 1 taken along the cross-sectional line AA in Fig. 1. Fig. 3A is a perspective view of the first surface P1 side of the piezoelectric vibrating element 20, and Fig. 3B is a perspective view of the second surface P2 side of the piezoelectric vibrating element 20.

[0010] 2, the piezoelectric vibration element 20 in the recess 10a includes a vibration reed 21, an excitation electrode 22, a mounting electrode 23, connection wiring 241 to 243, etc. The vibration reed 21 includes a vibration portion 211 that is thin in the Z direction, and a thick portion 212 that is thicker in the Z direction than the vibration portion 211. The thick portion 212 may protrude further to the +Z side from a first surface P1 on the +Z side of the vibration reed 21, and may also protrude further to the −Z side from a second surface P2 on the −Z side of the vibration portion 211.

[0011] 3A and 3B , the vibrating portion 211, i.e., the vibrating element 21, has a rectangular shape in a plan view, and is surrounded on at least two of its four sides by the thick portion 212 in a plan view. In one embodiment, the thick portion 212 may surround the vibrating portion 211 on all four sides.

[0012] As shown in Fig. 2, a pair of excitation electrodes 22 is located on both sides of the vibration part 211. The excitation electrodes 22 include a first excitation electrode 221 located on a first surface P1 of the vibration part 211 and a second excitation electrode 222 located on a second surface P2 of the vibration part 211. The first excitation electrode 221 and the second excitation electrode 222 may be located in the same position in a plan view. The thickness of the vibration part 211 is determined according to the resonance frequency of the piezoelectric vibration element 20. The resonance frequency of the piezoelectric vibration element 20 may be 75 MHz or higher, or may be 100 MHz or higher.

[0013] The thick portion 212 is provided with a set of mounting electrodes 23, connection wirings 241, 242, and 243, and a metal pattern 25. The mounting electrodes 23 include a first mounting electrode 231 and a second mounting electrode 232. The first mounting electrode 231 is connected to the first excitation electrode 221 via a connection wiring 241 on the first surface P1 side of the thick portion 212. The second mounting electrode 232 is located on the second surface P2 side of the thick portion 212 and is connected to the second excitation electrode 222 via a connection wiring 242. The first mounting electrode 231 and the second mounting electrode 232 are located at both ends of the +X side end of the thick portion 212 in the Y direction. Both the first mounting electrode 231 and the second mounting electrode 232 are connected to the electrode pad 11 located on the bottom surface of the recess 10a via a bonding member 15 on the second surface P2 side.

[0014] The connection wiring 243 is wiring for connecting to the testing electrodes. The connection wiring 243 is the remaining wiring portion connected to the testing electrodes on the wafer before each of the plurality of piezoelectric vibration elements 20 is cut from the wafer on which it is formed. The connection wiring 243 extends to the corner on the -X side and the -Y side. The piezoelectric vibration element 20 does not necessarily have to have the connection wiring 243.

[0015] The metal pattern 25 is located at the +Y side corner on the -X side. The metal pattern 25 has a first metal pattern 251 on the first surface P1 side and a second metal pattern 252 on the second surface P2 side. The first metal pattern 251 and the second metal pattern 252 have overlapping portions in a plan view. The first metal pattern 251 and the second metal pattern 252 may be electrically connected by a conductor pattern along the side surface of the thick portion 212. On the other hand, the metal pattern 25 is not electrically connected to other conductor members other than the metal pattern 25, such as the connection wiring 241 to 243, the excitation electrode 22, and the mounting electrode 23.

[0016] The first metal pattern 251 and the second metal pattern 252 have different shapes in a plan view. The first metal pattern 251 and the second metal pattern 252 each have a side perpendicular to the X-axis direction and a side perpendicular to the Y-axis direction inside the piezoelectric vibration element 20 in a plan view. For example, the first metal pattern 251 may be a rectangle having two sides that are shared with the sides of the piezoelectric vibration element 20. Furthermore, for example, the second metal pattern 252 may have an L-shape in which linearly extending portions are combined along two sides that sandwich the corner on the -X side and the +Y side. These four sides are positioned such that the two sides are visible through the vibrating reed 21 when the piezoelectric vibration element 20 is viewed from the top or from the bottom.

[0017] 4A and 4B are enlarged plan views of the metal pattern 25 and its vicinity. As shown in FIG. 4A , the first metal pattern 251 on the first surface P1 side is square in plan view, as indicated by the solid line, and has a first side S1 perpendicular to the X-axis direction and a second side S2 perpendicular to the Y-axis direction. The second metal pattern 252 on the second surface P2 side is L-shaped in plan view, as indicated by the dotted line. The tip of the portion of the second metal pattern 252 extending in the X-axis direction is a third side S3 perpendicular to the X-axis direction, and the tip of the portion extending in the Y-axis direction is a fourth side S4 perpendicular to the Y-axis direction.

[0018] In a plan view, the first metal pattern 251 is located closer to the front than the second metal pattern 252, so the first side S1 and the second side S2 of the first metal pattern are visible without the second metal pattern 252. Furthermore, the third side S3 and the fourth side S4 of the second metal pattern 252 are outside the range of the first metal pattern 251. Therefore, the entire area from the outer edge of the first metal pattern 251 to the second side S2 and the fourth side S4 is visible through the vibrating element 21.

[0019] In such a metal pattern 25, the distance d1 between the first side S1 and the third side S3, and the distance d2 between the second side S2 and the fourth side S4 are obtained in advance. When these distances d1 and d2 are actually measured in the obtained piezoelectric vibration element 20, the amount of positional deviation between these and the design values ​​becomes the amount of positional deviation when the metal pattern on the first surface P1 and the metal pattern on the second surface P2 are formed during the manufacturing of the piezoelectric vibration element 20.

[0020] On the wafer, the metal pattern 25 and the like are formed using a common photoresist or the like for the plurality of piezoelectric vibration elements 20. Therefore, the amount of misalignment of the metal pattern 25 is approximately equal to the amounts of misalignment of the other excitation electrodes 22, mounting electrodes 23, and connection wirings 241 to 243. The amounts of misalignment between the plurality of piezoelectric vibration elements 20 are also approximately equal. Therefore, the amount of misalignment of the metal pattern 25 in a certain piezoelectric vibration element 20 is collectively specified as the amount of misalignment of the planar position between the first excitation electrode 221 and the second excitation electrode 222 in the plurality of piezoelectric vibration elements 20 obtained from the same wafer.

[0021] A misalignment between the first excitation electrode 221 and the second excitation electrode 222 is likely to adversely affect the conversion efficiency between an electrical signal and vibration. Therefore, by setting a reference value for an allowable amount of misalignment in advance, piezoelectric vibration elements 20 that do not satisfy the reference can be easily and accurately extracted.

[0022] 4B is a plan view showing a modified example of the metal pattern 25. For example, the first metal pattern 251a may be a rectangle extending along the X-axis in a plan view, and the second metal pattern 252a may be a rectangle extending along the Y-axis in a plan view. The short side of the first metal pattern 251a is the first side S1a perpendicular to the X-axis direction, and the long side is the first side S1a perpendicular to the Y-axis direction. The long side of the second metal pattern 252a is the third side S3a perpendicular to the X-axis direction, and the short side is the fourth side S4a perpendicular to the Y-axis direction.

[0023] Therefore, the distance d1 in the X-axis direction between the first side S1a and the third side S3a is the amount of misalignment in the X-axis direction, and the distance d2 in the Y-axis direction between the second side S2a and the fourth side S4a is the amount of misalignment in the Y-axis direction. In this way, even if the shapes of the first metal pattern 251 and the second metal pattern 252 are simple, the amounts of misalignment in the X-axis direction and the Y-axis direction can be easily and accurately determined by combining them. In this case, to determine the distance d1, the first side S1a and the third side S3a can be visually recognized from the second surface P2 side, and to determine the distance d2, the second side S2a and the fourth side S4a can be visually recognized from the first surface P1 side.

[0024] As described above, the piezoelectric vibration element 20 of this embodiment includes a vibrating portion 211, a thick portion 212 that is thicker than the vibrating portion 211, and a vibrating element 21 that is rectangular in plan view and has a side parallel to the X-axis direction of the quartz crystal blank and a side parallel to the Y-axis direction, which is the Z'-axis direction perpendicular to the X-axis direction, and a metal pattern 25. The thick portion 212 is located along at least two sides of the vibrating element 21. The metal pattern 25 includes a first metal pattern 251 located in the thick portion 212 on a first surface P1 that is rectangular in plan view, and a second metal pattern 252 located in the thick portion 212 on a second surface P2 opposite the first surface P1, and is not electrically connected to any conductors other than the metal pattern 25. The first metal pattern 251 and the second metal pattern 252 have portions that overlap each other in plan view. The first metal pattern 251 has a first side S1 perpendicular to the X-axis direction and a second side S2 perpendicular to the Y-axis direction, which is perpendicular to the X-axis direction in a planar view. The second metal pattern 252 has a third side S3 perpendicular to the X-axis direction and a fourth side S4 perpendicular to the Y-axis direction. The area between the first side S1 and the third side S3 is outside the first metal pattern 251 or the second metal pattern 252. Furthermore, the area between the second side S2 and the fourth side S4 is outside the first metal pattern 251 or the second metal pattern 252. In other words, when the piezoelectric vibration element 20 is viewed from either the first surface P1 or the second surface P2, the parallel first side S1 and the third side S3 are simultaneously visible, and the parallel second side S2 and the fourth side S4 are simultaneously visible. This allows the distance d1 between the first side S1 and the third side S3 and the distance d2 between the second side S2 and the fourth side S4 to be easily determined, and the amount of deviation of the metal patterns on the first surface P1 and the second surface P2 from the design can be easily obtained accordingly. Therefore, the amount of deviation of the first excitation electrode 221 and the second excitation electrode 222 corresponding to the amount of deviation of the first metal pattern 251 and the second metal pattern 252 can also be obtained. This makes it easier to confirm the formation accuracy of the piezoelectric vibration element 20.

[0025] Furthermore, the region between the first side S1 and the third side S3 and the region between the second side S2 and the fourth side S4 may both be outside the first metal pattern 251 in a plan view. This makes it possible to determine the distance d1 and the distance d2 from the same surface. This reduces the effort required to check the accuracy of the piezoelectric vibration element 20.

[0026] Furthermore, the first metal pattern 251 and the second metal pattern 252 may be located at the corners of the vibrating element 21 in a plan view. This allows the metal pattern 25 to be significantly separated from other conductor patterns such as the excitation electrode 22, the mounting electrode 23, and the connection wiring 241 to 243, thereby reducing the risk of electrical continuity of the metal pattern 25. Furthermore, by locating the metal pattern 25 at a corner of the vibrating element 21, i.e., the piezoelectric vibrating element 20, the corner of the piezoelectric vibrating element 20 can be easily recognized by a user or by machines involved in the manufacture of the piezoelectric vibrator 1.

[0027] The piezoelectric vibration element 20 may also have a resonant frequency of 75 MHz or higher. In a high-frequency piezoelectric vibration element 20, vibrations concentrate near the excitation electrode 22, so not changing the shape of the excitation electrode 22 can reduce the impact on vibration. In a high-frequency piezoelectric vibration element 20, the relatively thick thick portion 212 located around the thin vibrating portion 211 is particularly effective in reducing breakage, trapping vibration energy, and stably fixing and supporting the piezoelectric vibration element 20. Therefore, by utilizing the metal pattern 25 on this thick portion 212, the amount of misalignment of the metal pattern between the first surface P1 and the second surface P2 can be accurately determined while reducing the adverse impact on vibration.

[0028] The vibrating element 21 may also be a quartz crystal element. The X-axis direction is set along the X-axis direction of the quartz crystal element, and the Y-axis direction is set along the Z'-axis direction of the quartz crystal element. By using a quartz crystal element, well-known frequency-temperature characteristics can be obtained. Furthermore, the high optical transparency of the quartz crystal element makes it easy to identify the amount of misalignment between the two surfaces.

[0029] Furthermore, the piezoelectric vibrator 1 of this embodiment may include the above-described piezoelectric vibration element 20 and a package 10 that houses the piezoelectric vibration element 20. Such a piezoelectric vibrator 1 can house the piezoelectric vibration element 20 whose accuracy has been more easily confirmed, thereby reducing the effort required to manufacture the piezoelectric vibrator 1.

[0030] Note that the above embodiment is merely an example, and various modifications are possible. For example, in the above, the metal pattern 25 is located at a corner different from the corner where the connection wiring 243 to the mounting electrode 23 and the testing electrode extends, but this is not limited to this. The metal pattern 25 does not have to be located at a planar view angle of the resonator element 21. Furthermore, the metal pattern 25 does not have to be in contact with the edge of the resonator element 21 in a planar view. For example, the metal pattern 25 may be located near the midpoint of one of the sides of the resonator element 21. Even in this case, the metal pattern 25 may be located at a distance from other conductor patterns such as the excitation electrode 22, the mounting electrode 23, and the connection wiring 241 to 243, thereby reducing the possibility of electrical conduction with these other conductor patterns.

[0031] Furthermore, the shape of the metal pattern 25 may be different from the shape shown above.

[0032] Furthermore, the designed distance d1 and distance d2 of the metal pattern 25 may not be the same. The metal pattern 25 may be determined to have an appropriate shape depending on the space of the thick portion 212, the positional relationship with other components, and the like.

[0033] Furthermore, the thick portion 212 may be located along two or three of the four sides of the vibrating element 21. That is, the vibrating portion 211 may be in contact with one or two of the four sides of the vibrating element 21. When the thick portion 212 is located along two sides, the two sides may be in contact with each other across a corner, or may be two sides that do not contact each other.

[0034] Furthermore, the shape of the excitation electrode 22 in plan view does not have to be rectangular. For example, the excitation electrode 22 may be circular, elliptical, or rectangular with rounded corners in plan view.

[0035] Furthermore, the positions of the pair of mounting electrodes 23 do not have to be aligned on one side in the longitudinal direction of the vibrating element 21. The pair of mounting electrodes 23 may be positioned on opposite sides in the longitudinal direction of the vibrating element 21, and may also be diagonally positioned on the vibrating element 21 in a plan view.

[0036] The vibrating element 21 does not have to be a quartz crystal element, but may be any element that can convert between electrical force and mechanical deformation and allows the rear surface to be seen through.

[0037] Furthermore, the piezoelectric vibrator 1 may have a package 10 with a different shape. For example, the recess 10a of the package 10 may have a step inside. Furthermore, the recess 10a does not have to be rectangular in plan view. For example, the corners of the inner surface of the recess 10a may be rounded. Furthermore, the package 10 may have a recess other than the recess 10a.

[0038] The bottom and side surfaces of the package 10 may be integral, or the package 10 may have separate bottom and side structures joined together.

[0039] Furthermore, the piezoelectric vibrator 1 may house other electronic components in addition to the piezoelectric vibrating element 20 in the recess 10a or another recess. The specific details of the structure, configuration, materials, size, etc. shown in the above embodiment may be modified as appropriate without departing from the spirit of the present disclosure. The scope of the present invention includes the scope of the invention described in the claims and their equivalents.

[0040] The present disclosure can be used for piezoelectric vibration elements and piezoelectric devices.

[0041] REFERENCE SIGNS LIST 1 Piezoelectric vibrator 10 Package 10a Recess 11 Electrode pad 15 Bonding member 20 Piezoelectric vibrating element 21 Vibrating piece 211 Vibrating portion 212 Thick portion 22 Excitation electrode 221 First excitation electrode 222 Second excitation electrode 23 Mounting electrode 231 First mounting electrode 232 Second mounting electrode 241 to 243 Connection wiring 25 Metal pattern 251 First metal pattern 252 Second metal pattern 30 Lid

Claims

1. A vibrating piece having a vibrating part and a thick part that is thicker than the vibrating part, the vibrating piece having a rectangular shape in plan view having a side parallel to a first direction and a side parallel to a second direction perpendicular to the first direction, and a metal pattern located on the thick part, the thick part being located along at least two sides of the vibrating piece, the metal pattern having a first metal pattern located on the thick part of a first surface of the rectangular shape in plan view, and a second metal pattern located on the thick part of a second surface opposite to the first surface, the metal pattern not being electrically connected to any conductor other than the metal pattern, the first metal pattern and the second metal pattern having portions that overlap each other in plan view, the first metal pattern having a first side perpendicular to the first direction and a second side perpendicular to a second direction perpendicular to the first direction in plan view, the second metal pattern having a third side perpendicular to the first direction and a fourth side perpendicular to the second direction, A piezoelectric vibration element, wherein an area between the first side and the third side is outside the first metal pattern or the second metal pattern, and an area between the second side and the fourth side is outside the first metal pattern or the second metal pattern.

2. The piezoelectric vibration element according to claim 1, wherein the region between the first side and the third side, and the region between the second side and the fourth side are both outside the first metal pattern in a planar view.

3. The piezoelectric vibration element according to claim 1 or 2, wherein the first metal pattern and the second metal pattern are located at corners of the vibration piece in a plan view.

4. A piezoelectric vibration element according to any one of claims 1 to 3, having a resonance frequency of 75 MHz or higher.

5. The piezoelectric vibration element according to any one of claims 1 to 4, wherein the vibration piece is a quartz crystal piece, the first direction is along an X-axis direction of the quartz crystal piece, and the second direction is along a Z'-axis direction of the quartz crystal piece.

6. A piezoelectric device comprising the piezoelectric vibration element according to any one of claims 1 to 5 and a package that houses the piezoelectric vibration element.

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