Tuning fork-type piezoelectric vibrating reed and tuning fork-type piezoelectric vibrator

Abstract

This tuning fork-type piezoelectric vibrating reed (2) is provided with: a base part (20); a pair of vibration arm parts (21, 22) extending in a first direction from one end (201) of the base part (20); an extension base part (23) protruding in a direction opposite to the first direction from the other end (202) of the base part (20); and an extension part (24) extending from the extension base part (23) to at least one second direction, which is orthogonal to the first direction, and has a reinforcement part (26) on a constricted part (250) formed by the extension base part (23), the base part (20), and the extension part (24). The reinforcement part (26) is formed in the second direction from the constricted part (250), and an end surface (261) in the second direction is formed in a substantially straight line in plan view.

Description

Tuning fork type piezoelectric vibrating piece and tuning fork type piezoelectric vibrator

[0001] The present invention relates to a tuning-fork type piezoelectric vibrating piece in which a pair of vibrating arms vibrates in a flexural vibration mode, and to a tuning-fork type piezoelectric vibrator equipped with the tuning-fork type piezoelectric vibrating piece.

[0002] Tuning-fork type piezoelectric vibrating pieces have been widely used as frequency sources for generating reference signals for clocks and the like.

[0003] As such a tuning fork-type piezoelectric vibrating piece, a tuning fork-type piezoelectric vibrating piece having a joint that is approximately L-shaped in a plan view has been disclosed (see Patent Document 1). Patent Document 1 describes that such a tuning fork-type piezoelectric vibrating piece prevents acoustic leakage and has a configuration that is suitable for miniaturization.

[0004] Patent Publication No. 2013-232944

[0005] However, in a configuration having a joint that is approximately L-shaped in plan view as described in Patent Document 1, a constriction is formed between the joint and the base, which is narrower than the width of the joint and the base. When an impact is applied to a tuning-fork-type piezoelectric vibrator equipped with a tuning-fork-type piezoelectric vibrating piece, there is a risk of the tuning-fork-type piezoelectric vibrating piece breaking at the constriction. In other words, for tuning-fork-type piezoelectric vibrating pieces with a constricted shape as described in Patent Document 1, for example, a tuning-fork-type piezoelectric vibrating piece with greater strength has been desired.

[0006] The present invention has been made in view of the above-mentioned problems, and has an object to provide a tuning-fork-type piezoelectric vibrating piece having higher strength and a tuning-fork-type piezoelectric vibrator equipped with the tuning-fork-type piezoelectric vibrating piece.

[0007] The present invention is characterized in that it is a tuning fork-type piezoelectric vibrating piece comprising a base, a pair of vibrating arms extending in a first direction from one end of the base, an extending base protruding from the other end of the base in a direction opposite to the first direction, and an extending portion extending from the extending base in at least one second direction perpendicular to the first direction, and having a reinforcing portion at a constricted portion formed by the extending base, the base, and the extending portion, the reinforcing portion being formed from the constricted portion toward the second direction, and the end face in the second direction being formed to be approximately straight in a planar view.

[0008] That is, the tuning-fork-type piezoelectric vibrating piece of the present invention has a reinforcing portion at a constricted portion formed by the extending base, the base, and the extending portion. The reinforcing portion is formed from the extending base toward a second direction, and the end face in the second direction is formed approximately linearly in a plan view. This configuration improves the strength of the portion of the tuning-fork-type piezoelectric vibrating piece that is narrower than the base (narrow portion). In other words, the strength of the portion where the constricted portion is formed (narrow portion) can be improved. That is, a tuning-fork-type piezoelectric vibrating piece can be made stronger while having a shape that prevents acoustic leakage and achieves miniaturization. More specifically, the configuration having a constricted portion as in the present invention can efficiently attenuate mechanical vibrations of the tuning-fork vibrating arm portion during operation and suppress the propagation of vibrations to the extending portion. That is, when the quartz crystal vibrating piece is held in a container, acoustic leakage can be reduced and the series resonance resistance (CI) can be lowered. With the configuration of the present invention, forming a reinforcing portion at this constricted portion improves the strength, i.e., impact resistance, without degrading the electrical characteristics of the vibrator.

[0009] The reinforcing portion may be configured to be inclined in the thickness direction from the extending portion side to the base portion side. With this configuration, the strength of the necked portion having the reinforcing portion can be further improved. In other words, the tuning-fork-type piezoelectric vibrating piece can be made stronger.

[0010] The reinforcing portion may be thinner than the base portion, which can prevent the reinforcing portion from interfering with the vibration of the tuning-fork type piezoelectric vibrating piece.

[0011] Furthermore, the tuning fork type piezoelectric vibrator may be configured as a tuning fork type piezoelectric vibrator having the tuning fork type piezoelectric vibrating piece of the present invention. With this configuration, the tuning fork type piezoelectric vibrator can have improved strength, i.e., impact resistance.

[0012] Furthermore, in the tuning-fork-type piezoelectric vibrator of the present invention, the tuning-fork-type piezoelectric vibrating piece may be housed in a recess of a container made of an insulating material, and the tuning-fork-type piezoelectric vibrating piece may be bonded to the inner bottom surface of the recess by a metal bump. This configuration allows the tuning-fork-type piezoelectric vibrating piece to be more firmly bonded to the container. Meanwhile, because the tuning-fork-type piezoelectric vibrating piece is more firmly bonded to the container, if the tuning-fork-type piezoelectric vibrating piece receives a strong impact while mounted, the impact will be greater at locations other than the metal bump bond. In other words, if an impact is applied to the constricted portion near the bond, the narrow portion, which has lower strength than the other portions, may break. However, the configuration with a reinforcing portion as in the present invention improves the strength of the narrow portion, thereby reducing the possibility of breakage. In other words, the tuning-fork-type piezoelectric vibrating piece can be more firmly bonded to the container while improving the strength of the tuning-fork-type piezoelectric vibrating piece.

[0013] In the tuning-fork-type piezoelectric vibrator of the present invention, two metal bumps may be provided, and the reinforcing portion may be located between the two metal bumps in the second direction. With this configuration, the reinforcing portion can further reduce the risk of damage to the tuning-fork-type piezoelectric vibrating piece.

[0014] According to the present invention, it is possible to provide a tuning-fork type piezoelectric vibrating piece and a tuning-fork type piezoelectric vibrator having higher strength.

[0015] FIG. 1 is a plan view of a tuning-fork type piezoelectric vibrator according to a first embodiment of the present invention. FIG. 2 is a schematic plan view of one main surface side of a tuning-fork type piezoelectric vibrating piece according to an embodiment of the present invention. FIG. 3 is an enlarged plan view of the vicinity of a reinforcing portion in this embodiment. FIG. 4 is a perspective view of the reinforcing portion in FIG. 3, viewed obliquely from above in direction A. FIG. 5 is a plan view of the reinforcing portion in FIG. 3, viewed from direction A. FIG. 6 is an enlarged plan view of the vicinity of a reinforcing portion in Alternative Embodiment 1. FIG. 7 is an enlarged plan view of the vicinity of a reinforcing portion in a modified version of Alternative Embodiment 1. FIG. 8 is an enlarged plan view of the vicinity of a reinforcing portion in Alternative Embodiment 2. FIG. 9 is a plan view of a tuning-fork type piezoelectric vibrating piece according to Alternative Embodiment 3. FIG. 10 is a plan view of a tuning-fork type piezoelectric vibrating piece according to Alternative Embodiment 4. FIG. 11 is a plan view of a tuning-fork type piezoelectric vibrating piece according to Alternative Embodiment 5. FIG. 12 is an enlarged view showing the planar shape of a through hole formed in the base of the tuning-fork type piezoelectric vibrating piece of FIG. 11. FIG. 13 is a cross-sectional view of the through hole of FIG. 12.

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in this specification, descriptions of various electrodes formed on the tuning-fork type piezoelectric vibrating piece are omitted. Furthermore, the X-axis direction (X-direction) in each drawing and this specification is the same as the X-axis direction of the quartz crystal axis, the Y-axis direction (Y-direction) is the same as the Y-axis direction of the quartz crystal axis (or the Y' direction tilted a few degrees from the Y-axis), and the Z-axis direction (Z-direction) is the same as the Z-axis direction of the quartz crystal axis (or the Z' direction tilted a few degrees from the Z-axis).

[0017] 1 is a plan view of a tuning-fork type piezoelectric vibrator 1 according to a first embodiment of the present invention. In this specification, the bottom and top are described with the depth direction in FIG. 1 being the bottom side of the tuning-fork type piezoelectric vibrator 1 and the front direction being the top side of the tuning-fork type piezoelectric vibrator 1.

[0018] The tuning fork type piezoelectric vibrator 1 (hereinafter referred to as the crystal vibrator 1) in this embodiment is a surface-mount type crystal vibrator having a substantially rectangular parallelepiped package structure. The crystal vibrator 1 may have, for example, outer dimensions in a plan view of 1.6 mm on the long side and 1.0 mm on the short side. However, the outer dimensions in a plan view of the crystal vibrator 1 are not limited to these dimensions, and may be various dimensions depending on the application.

[0019] 1, in the quartz crystal resonator 1 according to this embodiment, a tuning-fork type piezoelectric vibrating piece 2 (hereinafter referred to as the quartz crystal resonator piece 2) is housed in a recess 5 of a container 3 made of an insulating material, and then a flat lid (not shown) is bonded to the open end of the container 3 so as to cover the recess 5, thereby hermetically sealing the quartz crystal resonator piece 2 in the internal space. The container 3 and the lid are bonded together via a sealing material (not shown).

[0020] The container 3 is a box-shaped body made of an insulating material primarily composed of ceramic such as alumina, and can be formed, for example, by stacking three ceramic green sheets and firing them together. The container 3 has a rectangular recess 5 in plan view inside a frame-shaped bank portion 30, and a step portion 31 on which the quartz crystal vibrating piece 2 is mounted is provided in the recess 5. A sealing material (not shown) is formed in a frame shape in plan view on the upper surface 300 of the bank portion 30, and the sealing material corresponds to the outer periphery of the lid.

[0021] Two mounting pads 6a, 6b that are conductively bonded to the quartz crystal vibrating piece 2 are formed in parallel with a gap between them on the upper surface of the step portion 31. The two mounting pads 6a, 6b have opposite polarities and are electrically connected to a plurality of external connection terminals provided on the outer bottom surface of the container 3 via internal wiring and vias (not shown).

[0022] In this embodiment, the two mounting pads 6 a and 6 b are formed by laminating nickel and gold in this order on the upper surface of a tungsten metallization layer using a method such as plating. Note that molybdenum may be used as the metallization layer instead of tungsten.

[0023] The bonding portions 7a and 7b of the quartz crystal vibrating piece 2 and the mounting pads 6a and 6b are conductively bonded to each other using Flip Chip Bonding (FCB) with metal bumps. That is, metal bumps are formed on the bonding portions 7a and 7b. In this embodiment, the quartz crystal vibrating piece 2 is mounted on the step portion 31 so that the constricted portion of the quartz crystal vibrating piece 2 overlaps the end face of the step portion 31. In this embodiment, the bonding portions 7a and 7b are formed with gold (Au) metal bumps. Therefore, the bonding portions 7a and 7b and the mounting pads 6a and 6b are conductively bonded to each other using gold-to-gold diffusion bonding.

[0024] The lid may be, for example, a metal lid body having a rectangular shape in plan view and made of Kovar as a base. The lid and the container 3 may be joined by, for example, forming a metallic brazing material around the outer periphery of the lid on a nickel-plated layer on the joining surface of the lid that is to be joined to the container 3, and then brazing the lid to the container. The lid and the container may be joined by seam welding instead of brazing.

[0025] Fig. 2 is a schematic plan view of one main surface of the tuning-fork type piezoelectric vibrating piece 2 according to an embodiment of the present invention, and Fig. 3 is an enlarged plan view of the vicinity of the reinforcing portion 26 in this embodiment. For ease of explanation, of the two opposing main surfaces of the quartz crystal vibrating piece 2, the main surface that faces the mounting pads 6a, 6b when mounted on the container 3 will be referred to as the back surface, and the main surface opposite the back surface will be referred to as the front surface. In other words, Fig. 2 is a plan view of the quartz crystal vibrating piece 2 as seen from the front surface side.

[0026] The quartz crystal vibrating piece 2 is a thin quartz crystal Z plate having a thickness in the Z direction. The quartz crystal vibrating piece 2 includes a base 20, a pair of vibrating arms 21 and 22 that are aligned and protrude (extend) in the +Y direction (first direction) from one end 201 (one end side) of the base 20, an extension base 23 that protrudes in the -Y direction from the other end 202 (other end side) of the base 20 that faces the one end 201, and an extension portion 24 that protrudes (extends) in the +X direction (second direction) from an end 231 of the extension base 23 on the opposite side from the base 20. Therefore, the quartz crystal vibrating piece 2 has a tuning fork shape in plan view, and the end where the extension base 23 is provided is formed into a substantially L-shape by the extension base 23 and the extension portion 24 in plan view. In this embodiment, the vibrating arms 21 and 22 are formed to extend in the +Y direction, but they may also be formed to extend in the -Y direction. In addition, in this embodiment, the extension portion 24 is formed to extend in the +X direction, but it may be formed to extend in the −X direction.

[0027] That is, in the quartz crystal vibrating piece 2 of the present invention, the extended base portion 23 has a narrow portion 25 that is narrower than the other portions in the X-axis direction as the width direction, and a constricted portion 250 formed at the +X-direction end of the narrow portion 25. In other words, in the quartz crystal vibrating piece 2 of the present invention, the base portion 20, the extended portion 24, and the extended base portion 23 form a recess that is concave in the −X direction in a plan view.

[0028] Furthermore, the constricted portion 250 is provided with a reinforcing portion 26 formed at least in the second direction (+X direction) from the side surface of the extending base portion 23. The reinforcing portion 26 in this embodiment is formed integrally with the base portion 20, the extending base portion 23, and the extending portion 24, and the outer end portion in the +X direction is formed as an end surface 261.

[0029] The shape of the quartz crystal vibrating piece 2 of this embodiment (the vibrating arms 21, 22, base 20, extending base 23, extending portion 24 that constitute the quartz crystal vibrating piece 2, the narrow portion 25 formed by these, the constricted portion 250, and the reinforcing portion 26 provided on the constricted portion 250) is formed by wet etching from a quartz crystal blank (not shown), which is a quartz crystal piece made of anisotropic material.

[0030] In this embodiment, the base 20 has a shape that is symmetrical in a plan view (symmetrical in the X direction). The base 20 is formed to be wider than the vibrating arms 21 and 22. The other end 202 of the base 20 is formed so that its width gradually narrows from the vibrating arms 21 and 22 side to the extending base 23 side.

[0031] Wide portions 211, 221 (weight portions) that are wider than the arm width (the dimension of the arm in the first direction) of the vibrating arms 21, 22 are formed on the tip side of each of the pair of vibrating arms 21, 22. The wide portions 211, 221 are formed integrally with the tip portions of the vibrating arms 21, 22 via wide portions that gradually widen in the second direction (+X direction). That is, the wide portions and the wide portions 211, 221 are formed integrally with the vibrating arms 21, 22. Note that each corner on the tip side of the wide portions 211, 221 is chamfered. The vibrating arms 21, 22, the wide portions, and the wide portions 211, 221 have a pair of main surfaces facing each other in the Z direction and a pair of side surfaces facing each other in the X direction.

[0032] Long grooves are formed on the front and back main surfaces of each of the pair of vibrating arms 21 and 22 in order to further reduce the equivalent series resistance (Crystal Impedance, CI value). More specifically, a long groove 212 is formed on the front main surface (front surface) of the vibrating arm 21, and a long groove (not shown) is formed on the back main surface (back surface) of the vibrating arm 21, so that the long grooves face each other. Furthermore, a long groove 222 is formed on the front main surface (front surface) of the vibrating arm 22, and a long groove (not shown) is formed on the back main surface (back surface) of the vibrating arm 22, so that the long grooves face each other. The long grooves 212 and 222 formed on the front surfaces of the vibrating arms 21 and 22 and the long groove (not shown) formed on the back surface of the vibrating arms 21 and 22 are formed with a predetermined depth (length in the Z direction) and width (length in the X direction) on the front and back main surfaces of the vibrating arms 21 and 22. Furthermore, one end of each long groove in the Y direction is formed up to the region of one end 201 of the base 20, and the other end is formed to be located on the base side of the vibrating arms 21, 22 with respect to the boundary between the vibrating arms 21, 22 and the widened portion. That is, all of the long grooves have a longitudinal direction along the direction in which the vibrating arms 21, 22 protrude (first direction, +Y direction) and a width direction along the direction in which the vibrating arms 21, 22 are arranged side by side (second direction, +X direction). Furthermore, each long groove is formed by wet etching.

[0033] The extending base 23 is formed so as to protrude in the -Y direction from the other end 202 of the base 20. That is, the extending base 23 is formed so as to protrude from the other end side of the base 20 in the direction opposite to the first direction. Moreover, the extending base 23 is formed continuously from the other end 202 of the base 20, which is formed so as to gradually narrow. Therefore, the extending base 23 is formed so as to be narrower than the base 20. The extending base 23 is formed continuously with the extending portion 24 that protrudes in the +X direction from the end 231 opposite the base 20. Moreover, the extending base 23 has a joint 7a at the end in the -X direction (the end opposite the extending portion 24) of the end 231 opposite the base 20 on the back surface.

[0034] The bonding portion 7a is bonded to the mounting pad 6a of the container 3 when the quartz crystal vibrating piece 2 is mounted on the container 3. In this embodiment, the bonding portion 7a is a plated bump (metal bump) formed by electrolytic plating, and more specifically, is an Au plated bump.

[0035] The extension portion 24 is formed continuously so as to protrude in the +X direction from an end 231 of the extension base 23 opposite the base 20. In this embodiment, the extension portion 24 is formed in a substantially rectangular shape with a uniform width (length in the Y direction) from the end on the extension base 23 side to the end in the extension direction (+X direction). In addition, the extension portion 24 has a joint 7b at the end in the +X direction on the back surface (the end opposite the extension base 23).

[0036] The bonding portion 7b is bonded to the mounting pad 6b of the container 3 when the quartz crystal vibrating piece 2 is mounted on the container 3. In this embodiment, the bonding portion 7b is a plated bump (metal bump) formed by electrolytic plating, and more specifically, is an Au plated bump.

[0037] The extension portion 24 is not directly connected to or formed continuously with the base portion 20. That is, the quartz crystal vibrating piece 2 has the base portion 20, the extension base portion 23, and the extension portion 24 formed continuously in this order, with the extension base portion 23 formed between the base portion 20 and the extension portion 24.

[0038] The quartz crystal vibrating piece 2 also includes first and second excitation electrodes configured at different potentials, and lead-out electrodes extending from the first and second excitation electrodes via lead-out electrodes. The first excitation electrode is formed on the front and back main surfaces of one vibrating arm 21 and on the outer and inner surfaces of the other vibrating arm 22 via the lead-out electrodes. Similarly, the second excitation electrode is formed on the front and back main surfaces of the other vibrating arm 22 and on the outer and inner surfaces of one vibrating arm 21 via the lead-out electrodes. The lead-out electrode extending from the first excitation electrode is connected to the joint 7b, and the lead-out electrode extending from the second excitation electrode is connected to the joint 7a. The electrode patterns are not shown in the drawings.

[0039] The quartz crystal vibrating piece 2 has a narrow portion 25 in the extended base portion 23 that narrows in the X direction. That is, the quartz crystal vibrating piece 2 has a constricted portion 250 formed by the base portion 20, the extended base portion 23, and the extended portion 24. In other words, the quartz crystal vibrating piece 2 has a recess that is recessed in the −X direction and is formed by the base portion 20, the extended base portion 23, and the extended portion 24.

[0040] The quartz-crystal vibrating piece 2 also has a reinforcing portion 26 formed from the end side surface of the constricted portion 250 in the +X direction (the side surface on which the extending portion 24 is provided) toward the +X direction (second direction). The reinforcing portion 26 is located between the two bonding portions 7 a and 7 b in the X direction.

[0041] The reinforcement portion 26 has an end face 261 in the +X direction (second direction) that is formed to be substantially straight in a plan view. In other words, the open end face 261 of the reinforcement portion 26 is formed to be substantially straight. In this embodiment, the end face 261 is formed to be substantially parallel to the Y direction. Note that the term "substantially straight" here refers to a straight line that includes minute irregularities. In other words, when the end face 261 is observed under magnification, minute irregularities may be visible, but even in such cases, the line can be expressed as a substantially straight line.

[0042] FIG. 4 is a perspective view of the reinforcement portion 26 in FIG. 3 as viewed from diagonally above in the direction A, and FIG. 5 is a plan view of the reinforcement portion 26 as viewed from the direction A in FIG. 3. The reinforcement portion 26 is thinner than the base portion 20, the extending base portion 23, and the extending portion 24. That is, the reinforcement portion 26 is thinner than the narrow portion 25. Furthermore, the reinforcement portion 26 in this embodiment is formed to be inclined at an angle α in the thickness direction from the extending portion 24 side to the base portion 20 side. In this embodiment, the inclination is formed to transition in the −Z direction from the extending portion 24 side to the base portion 20 side. That is, the angle α indicates the degree to which the reinforcement portion 26 is inclined in the Z direction and indicates the angle formed between an imaginary line parallel to the Y direction and an end face 261 of the reinforcement portion 26.

[0043] The above configuration makes it possible to provide a tuning-fork-type piezoelectric vibrating piece 2 with higher strength. The tuning-fork-type piezoelectric vibrating piece 2 (quartz crystal vibrating piece 2) of the present invention has a configuration with a constricted portion 250. This configuration efficiently attenuates mechanical vibrations in the tuning-fork vibrating arm portion during operation and suppresses propagation of vibrations to the extension portion. In other words, when the quartz crystal vibrating piece 2 is held in the container 3, acoustic leakage can be reduced, and the series resonance resistance (CI) can be lowered.

[0044] Furthermore, the tuning-fork-type piezoelectric vibrating piece 2 (quartz crystal vibrating piece 2) of the present invention has a reinforcing portion 26 formed from the side of the constricted portion 250 toward the +X direction, and the end face 261 of the reinforcing portion 26 in the +X direction is formed to be approximately linear in plan view. This configuration can improve the strength of the narrow portion 25, which has lower strength than other portions. In particular, as shown in FIG. 1 , when the tuning-fork-type piezoelectric vibrating piece 2 is mounted in the container 3, the narrow portion 25 and the constricted portion 250 may overlap the end face of the step portion 31 in plan view. In such cases, if the tuning-fork-type piezoelectric vibrating piece 2 receives an impact in the thickness direction or if large vibrations occur in the thickness direction, there is a possibility that the narrow portion 25 may break. However, with the configuration of the present invention, the strength of the narrow portion 25 is improved by the reinforcing portion 26, thereby reducing the possibility of breakage.

[0045] Furthermore, the tuning-fork-type piezoelectric vibrating piece 2 (quartz crystal vibrating piece 2) of the present invention is mounted on the container 3 by bump bonding using metal bumps (bonding portions 7a, 7b). Specifically, the tuning-fork-type piezoelectric vibrating piece 2 is housed in a recess 5 of the container 3 made of an insulating material, and the tuning-fork-type piezoelectric vibrating piece 2 is bonded to the inner bottom surface of the recess 5 by metal bumps (bonding portions 7a, 7b). This configuration allows the tuning-fork-type piezoelectric vibrating piece 2 to be more firmly bonded to the container 3. On the other hand, because the tuning-fork-type piezoelectric vibrating piece 2 is more firmly bonded to the container 3, if the tuning-fork-type piezoelectric vibrating piece 2 receives a strong impact while mounted, the impact will be greater in areas other than the bonding portions 7a, 7b. In other words, if an impact is applied to the constricted portion 250 near the bonding portion, there is a possibility that the narrow portion 25, which has lower strength than other portions, will break. However, with the configuration of the present invention, the strength of the narrow portion 25 is improved by the reinforcing portion 26, reducing the possibility of breakage. That is, the tuning-fork-type piezoelectric vibrating piece 2 can be more firmly bonded to the container 3 while improving the strength of the tuning-fork-type piezoelectric vibrating piece 2. The bump bonding shown in this embodiment can firmly bond the container and the quartz vibrating piece. That is, it is a configuration that can achieve a strong and stable electrical and mechanical bond. However, on the other hand, there is a concern that the cushioning function of the bonding material (adhesive) is not fully functioned, which may reduce impact resistance. The present invention can achieve a strong and stable electrical and mechanical bond, as well as improved strength, such as improved impact resistance. Furthermore, since the reinforcing portion 26 is located between the two metal bumps (bonding portions 7a, 7b) in the second direction, i.e., the X direction, the reinforcing portion 26 can further reduce the risk of damage to the tuning-fork-type piezoelectric vibrating piece 2.

[0046] Furthermore, the reinforcing portion 26 of the present invention has an end surface 261 in the +X direction formed substantially parallel to the Y direction. This configuration prevents the impact applied to the reinforcing portion 26 from concentrating on one point. In other words, the strength of the narrow width portion 25 can be further improved.

[0047] Furthermore, the reinforcing portion 26 of the present invention is formed to be thinner than the base portion 20, the extending base portion 23, and the extending portion 24. This configuration can prevent the reinforcing portion 26 from interfering with the vibration of the tuning-fork-type piezoelectric vibrating piece 2.

[0048] Other Embodiments The present invention is not limited to the configuration of the first embodiment described above, and many other embodiments can be achieved. FIG. 6 is an enlarged plan view of the vicinity of the reinforcing portion 26 in another embodiment 1, and FIG. 7 is an enlarged plan view of the vicinity of the reinforcing portion 26 in a modified version of another embodiment 1. For example, in the first embodiment, the end surface 261 of the reinforcing portion 26 is formed substantially parallel to the Y direction. However, the end surface 261 may be formed to have an angle β with respect to the Y direction as long as it is formed substantially linearly. In such a case, the angle β is preferably 60 degrees or less, more preferably 45 degrees or less, and even more preferably 30 degrees or less. Even with such a configuration, the same effects as those of this embodiment can be achieved.

[0049] FIG. 8 is an enlarged plan view of the vicinity of the reinforcing portion 26 in Alternative Embodiment 2. Furthermore, for example, a protruding portion 262 protruding (standing up) in the +X direction (the opposite direction from the constricted portion 250) may be provided at the end of the end surface 261 of the reinforcing portion 26 on the extension portion 24 side or the base portion 20 side. The protruding portion 262 is connected to the extension portion 24 or the base portion 20 and is formed so that its width (length in the Y direction) gradually narrows along the outer shape of the extension portion 24 or the base portion 20. In this case, the angle γ between the protruding portion 262 and the end surface 261 is preferably 90 degrees or greater. Furthermore, the width (length in the Y direction) of the base portion (standing portion) of the protruding portion 262 protruding from the end surface 261 is preferably 20% or less of the length of the end surface 261, more preferably 10% or less, and even more preferably 5% or less. This configuration can further improve the strength of the narrow width portion 25.

[0050] FIG. 9 is a plan view of a tuning-fork-type piezoelectric vibrating piece 2 according to another embodiment 3, and FIG. 10 is a plan view of a tuning-fork-type piezoelectric vibrating piece 2 according to another embodiment 4. In the first embodiment, the extension portion 24 extends only in the +X direction (second direction) from the extension base portion 23, but this is not limiting. For example, the extension portion 24 may extend only in the −X direction from the extension base portion 23. Alternatively, as shown in FIG. 9, the extension portion 24 may include a first extension portion 241 extending from the extension base portion 23 in the +X direction and a second extension portion 242 extending in the −X direction. In such a case, the position of the joint portion 7a can be the end of the second extension portion 242. In addition, the reinforcing portion 26 may be provided in the first constriction portion 251 that contacts the first extension portion 241, or in the second constriction portion 252 that contacts the second extension portion 242, or may be provided in both the first constriction portion 251 and the second constriction portion 252.

[0051] 10 , the extension base 23 may include a first extending portion 241 extending in the +X direction and a second extending portion 242 extending in the −X direction, with the first extending portion 241 and the second extending portion 242 extending a predetermined length being bent perpendicularly to the +Y direction (first direction). In such a case, the joints 7 a and 7 b may be located at the bent ends of the first extending portion 241 and the second extending portion 242. Furthermore, the reinforcing portion 26 may be provided in the first constricted portion 251 that contacts the first extending portion 241, in the second constricted portion 252 that contacts the second extending portion 242, or in both the first constricted portion 251 and the second constricted portion 252.

[0052] Fig. 11 is a plan view of a tuning-fork-type piezoelectric vibrating piece 2 in another embodiment 5, Fig. 12 is an enlarged view showing the planar shape of a through-hole 21c formed in the base 20 of the tuning-fork-type piezoelectric vibrating piece 2 in Fig. 11, and Fig. 13 is a cross-sectional view of the through-hole 21c in Fig. 12. In the first embodiment, no through-holes are provided in the base 20 of the tuning-fork-type piezoelectric vibrating piece 2, but for example, as shown in Figs. 11 to 13, through-holes 21c, 22c may be provided in the base 20 of the tuning-fork-type piezoelectric vibrating piece 2. The through-holes 21c, 22c can be formed simultaneously when the outer shape of the tuning-fork-type piezoelectric vibrating piece 2 is formed by wet etching.

[0053] 11, through holes 21c, 22c are used to route lead electrodes 21b, 22b drawn from a pair of excitation electrodes 21a, 22a, respectively. Specifically, as shown in FIG. 11, a first excitation electrode 21a and a second excitation electrode 22a, which are configured at different potentials, are formed on a pair of vibrating arms 21, 22 of the tuning-fork-type piezoelectric vibrating reed 2, and lead electrodes 21b, 22b drawn from the first excitation electrode 21a and the second excitation electrode 22a, respectively, are formed on each of the base 20, the pair of vibrating arms 21, 22, the extending base 23, the extending portion 24, etc. of the tuning-fork-type piezoelectric vibrating reed 2. The pair of excitation electrodes 21a, 22a and the lead electrodes 21b, 22b are formed on both the front and back main surfaces of the tuning-fork-type piezoelectric vibrating reed 2.

[0054] The through holes 21c, 22c are formed in the formation region of the extraction electrodes 21b, 22b in the base 20 of the tuning-fork-type piezoelectric vibrating piece 2, and conductive electrodes (not shown) are formed inside the through holes 21c, 22c. The conductive electrodes formed inside the through holes 21c, 22c may be formed only on the wall surfaces S1 of the through holes 21c, 22c, or may be formed with the conductive electrodes filled in the through holes 21c, 22c. With this configuration of the through holes 21c, 22c, the extraction electrodes 21b, 22b formed on the front main surface of the tuning-fork-type piezoelectric vibrating piece 2 are routed to the extraction electrodes 21b, 22b of the same polarity on the back main surface. The extraction electrode 21b, which is extracted from the first excitation electrode 21a, is connected to the joint 7a formed on the back main surface of the tuning-fork-type piezoelectric vibrating piece 2. Furthermore, the extraction electrode 22b extracted from the second excitation electrode 22a is connected to the joint 7b formed on the rear main surface of the tuning-fork-type piezoelectric vibrating piece 2. In the second direction, the X direction, the above-mentioned reinforcing portion 26 is located between the two metal bumps (joints 7a, 7b), and the joint 7a located in the -X direction from the reinforcing portion 26 is formed larger than the joint 7b located in the +X direction from the reinforcing portion 26. On the front main surface of the tuning-fork-type piezoelectric vibrating piece 2, as shown in FIG. 11, the extraction electrodes 21b, 22b are not formed in a portion on the -Y direction side of the narrow width portion 25. On the other hand, on the rear main surface of the tuning-fork-type piezoelectric vibrating piece 2, the extraction electrodes 21b, 22b are also formed in a portion on the -Y direction side of the narrow width portion 25, although this is not shown.

[0055] Here, the planar shapes and cross-sectional shapes of the through holes 21c and 22c will be described with reference to FIGS. 12 and 13. While FIGS. 12 and 13 show the through hole 21c as a representative example, the through hole 22c has a similar configuration. As shown in FIG. 12, the inner walls of the through holes 21c and 22c are composed of a plurality of wall surfaces S1, which form the inner walls of the through holes 21c and 22c in a spiral shape. Furthermore, as shown in FIG. 13, the planar areas of the through holes 21c and 22c (opening areas related to the opening diameter and opening width of the through holes 21c and 22c) gradually decrease from the ends T1 and T2 of the through holes 21c and 22c on both the front and back principal surfaces of the tuning-fork-type piezoelectric vibrating piece 2 toward the interior T3 of the tuning-fork-type piezoelectric vibrating piece 2, like an hourglass. Such through holes 21c, 22c can be configured by optimally setting the temperature and concentration of the etching solution to prevent over-etching when forming the through holes 21c, 22c in an anisotropic crystalline material such as quartz by wet etching, and by optimally managing the etching time.

[0056] 12 and 13, external stress can be dispersed while gradually weakening along the spirally arranged (formed) multiple wall surfaces S1, and a portion of the vibration energy generated by the vibration of the pair of vibrating arms 21 and 22, which are the vibrating parts, can also be released while gradually weakening along the spiral wall surfaces S1 of the through holes 21 c and 22 c. Furthermore, the planar area of ​​the through holes 21 c and 22 c can be gradually reduced from both ends T1 and T2 of the through holes 21 c and 22 c toward the interior T3 of the through holes 21 c and 22 c, so the surface area of ​​the through holes 21 c and 22 c can be increased, and the conduction state of the conductive electrodes can be stabilized.

[0057] In this way, by providing the through holes 21c, 22c in the tuning-fork-type piezoelectric vibrating piece 2, the propagation of vibration energy can be efficiently blocked by the through holes 21c, 22c, vibration leakage can be prevented, and the tuning-fork-type piezoelectric vibrating piece 2 can have good characteristics. On the other hand, by providing the through holes 21c, 22c in the tuning-fork-type piezoelectric vibrating piece 2, there is a possibility that cracks will occur that start from the constricted portion 250 and connect to the through holes 21c, 22c, but with the configuration of the present invention, the strength of the narrow portion 25 is improved by the reinforcing portion 26, so the possibility of such cracks can be reduced.

[0058] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments, but should be defined by the scope of the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included.

[0059] This application claims priority based on Japanese Patent Application No. 2023-141374, filed in Japan on August 31, 2023, the entire contents of which are incorporated herein by reference.

[0060] The tuning-fork type piezoelectric vibrating piece of the present invention can be used in the industry of manufacturing and selling tuning-fork type piezoelectric vibrating pieces and tuning-fork type piezoelectric vibrators equipped with the tuning-fork type piezoelectric vibrating pieces.

[0061] DESCRIPTION OF SYMBOLS 1... tuning fork type piezoelectric vibrator 2... tuning fork type piezoelectric vibrating piece 3... container 7a, 7b... joint portion 20... base portion 21, 22... vibrating arm portion 23... extending base portion 24... extending portion 25... narrow width portion 250... constricted portion 26... reinforcing portion 261... end surface

Claims

1. A tuning-fork-type piezoelectric vibrating piece comprising: a base; a pair of vibrating arms extending in a first direction from one end of the base; an extending base protruding from the other end of the base in a direction opposite to the first direction; and an extending portion extending from the extending base in at least one second direction perpendicular to the first direction, wherein the tuning-fork-type piezoelectric vibrating piece has a reinforcing portion at a constricted portion formed by the extending base, the base, and the extending portion, the reinforcing portion being formed from the constricted portion toward the second direction, and the end face in the second direction being formed to be approximately straight in a planar view.

2. A tuning-fork type piezoelectric vibrating piece according to claim 1, wherein the reinforcing portion is inclined in the thickness direction from the extension portion side to the base portion side.

3. A tuning-fork type piezoelectric vibrating piece according to claim 2, wherein the reinforcing portion is thinner than the base portion.

4. A tuning-fork type piezoelectric vibrator comprising a tuning-fork type piezoelectric vibrating piece according to any one of claims 1 to 3.

5. A tuning fork type piezoelectric vibrator according to claim 4, characterized in that the tuning fork type piezoelectric vibrating piece is housed in a recess of a container made of an insulating material, and the tuning fork type piezoelectric vibrating piece is bonded to the inner bottom surface of the recess by a metal bump.

6. A tuning-fork type piezoelectric vibrator according to claim 5, characterized in that two metal bumps are provided, and the reinforcing portion is located between the two metal bumps in the second direction.

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