Piezoelectric vibrating piece and piezoelectric vibrator

Abstract

To prevent a piezoelectric vibrating piece from being damaged by an acute-angled structure formed by an etching residue in the piezoelectric vibrating piece including a piezoelectric plate made of crystal.SOLUTION: A piezoelectric vibrating piece 3 includes a piezoelectric plate 30 made of crystal, and the piezoelectric plate 30 includes a base 35, a pair of a first vibrating arm 31 and a second vibrating arm 32 connected to the base 35, and a first support arm 33 and a second support arm 34 connected to the base 35, and includes a first recess 50 and a second recess 51 formed by one or more of the base 35, the first vibrating arm 31, the second vibrating arm 32, the first support arm 33, and the second support arm 34, and includes a widened portion 36 provided in the first recess 50 and the second recess 51 and suppressing the occurrence of the acute angle structure formed by the etching residue of the first recess 50 and the second recess 51 when viewed from the thickness direction of the base 35.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a piezoelectric vibrating piece and a piezoelectric vibrator. [Background technology]

[0002] For example, Patent Document 1 discloses a tuning fork type crystal element having a support arm connected to a base and a pair of vibrating arms connected to the base. The tuning fork type crystal element disclosed in Patent Document 1 has a first support arm extending from one side of a flat base and a second support arm extending from the tip of the first support arm along the vibrating arm, and further has a notch provided at an outer corner of the second support arm. According to such a tuning fork type crystal element disclosed in Patent Document 1, it is possible to prevent the outer corner of the second support arm from coming into contact with a conveying device or the like and being chipped during the manufacturing process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-88576 A Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, the piezoelectric vibrating piece made of the tuning fork type crystal element as described above has a piezoelectric plate made of crystal. This piezoelectric plate generally has a recess formed by one or more of the base, the support arm, and the support arm. For example, in a side arm type piezoelectric vibrating piece in which an L-shaped support arm is connected to the base, the recess is formed by the side of the support arm and the side of the base. In addition, in a center arm type piezoelectric vibrating piece in which the vibrating arm extends linearly parallel to the support arm with a single support arm sandwiched therebetween, the recess is formed by the side of the support arm, the side of the base, and the side of the vibrating arm. When a piezoelectric plate made of crystal is formed by wet etching, etching residues are generated that are not etched and remain in the recess. Such etching residues form a crack-like acute angle structure with a pointed back. The acute angle structure may be the starting point of cracks that occur in the piezoelectric vibrating piece, and may cause the support arm or the like to break.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to prevent damage to a piezoelectric vibrating piece having a piezoelectric plate formed from quartz crystal caused by a sharp-angle structure formed by etching remnants. [Means for solving the problem]

[0006] The present invention employs the following configuration as a means for solving the above problems.

[0007] A first aspect of the present invention is a piezoelectric vibrating piece having a piezoelectric plate made of quartz crystal, the piezoelectric plate having a base, a pair of vibrating arms connected to the base, and a pair of supporting arms connected to the base, the vibrating arms and the supporting arms each having a recess formed on a plane between the vibrating arms and the supporting arms, and a corner formed in the recess. To bury it and a widened portion provided on the support arm portion, the widened portion having a larger protrusion amount on the support arm portion side than on the vibrating arm portion side.

[0008] The shape of the etching residue in a piezoelectric plate made of quartz is determined depending on the direction of the crystal axis. That is, when a piezoelectric plate having the same crystal axis direction is formed, the etching residue will have the same shape. Therefore, the shape of the etching residue generated in the piezoelectric plate can be predicted in advance, and the shape and position of the acute angle structure formed by such etching residue can also be predicted. In the present invention, an acute angle structure generation suppression functional part is provided to suppress the generation of an acute angle structure in the etching residue whose shape and position can be predicted in advance. In addition, the acute angle structure generation suppression functional part is provided in a narrow recess formed by one or more of the base, the vibrating arm, and the supporting arm. Although an acute angle structure due to the etching residue is likely to occur in such a narrow recess, according to the present invention, the acute angle structure generation suppression functional part can suppress the generation of an acute angle structure in the recess compared to a case where the acute angle structure generation suppression functional part is not provided. Therefore, according to the present invention, in a piezoelectric vibrating piece having a piezoelectric plate made of quartz, it is possible to suppress the piezoelectric vibrating piece from being damaged by an acute angle structure formed by the etching residue. Furthermore, since the acute angle structure generation suppression functional portion is a widening portion, it is possible to improve the strength of the piezoelectric vibrating reed compared to, for example, when the acute angle structure generation suppression functional portion is a groove portion or the like. Therefore, according to the present invention, it is possible to more reliably prevent the piezoelectric vibrating reed from being damaged. In addition, it is possible to make the contact area of ​​the widening portion with the vibrating arm portion smaller than the contact area of ​​the widening portion with the supporting arm portion. Therefore, it is possible to reduce the influence of the widening portion on the vibration of the vibrating arm portion, and it is possible to prevent the widening portion from affecting the vibration characteristics of the piezoelectric vibrating reed.

[0017] The present invention 2 The embodiment of the present invention is as follows: A curved surface is provided to connect the side surface of the vibrating arm portion and the side surface of the supporting arm portion. The following configuration is adopted.

[0018] According to the present invention, the connection angle between the surface of the widening portion and the inner wall surface of the recess can be made shallow, making it possible to prevent the occurrence of an acute angle structure due to residual etching at the boundary between the widening portion and the inner wall surface of the recess.

[0029] The present invention 3 The aspect of the present invention is a piezoelectric vibrator, or No. of 2 and a package in which the piezoelectric vibrating piece is hermetically sealed and in which the piezoelectric vibrating piece is mounted via the supporting arm portion.

[0030] According to the present invention, it is possible to provide a piezoelectric vibrator capable of preventing damage to the piezoelectric vibrating piece caused by an acute angle structure due to etching residue. Effect of the Invention

[0031] According to the present invention, in a piezoelectric vibrating piece having a piezoelectric plate made of quartz crystal, it is possible to prevent the piezoelectric vibrating piece from being damaged by an acute angle structure formed by etching residue. [Brief description of the drawings]

[0032] [Figure 1] 1 is an external perspective view of a piezoelectric vibrator according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a plan view of the piezoelectric vibrator with the sealing plate removed. [Diagram 3] 3 is a cross-sectional view corresponding to line II in FIG. 2. [Figure 4] 1 is an exploded perspective view of a piezoelectric vibrator according to a first embodiment of the present invention. [Diagram 5] 1 is a plan view of a piezoelectric vibrating piece according to a first embodiment of the present invention. [Figure 6] 6 is a cross-sectional view corresponding to line II-II in FIG. 5. [Figure 7] FIG. 2(a) is a schematic enlarged view including a first recess of a piezoelectric plate according to a first embodiment of the present invention, and (b) is a schematic enlarged view of the first recess when no widened portion is provided. [Figure 8] 4 is a flowchart showing a method for manufacturing the piezoelectric vibrating piece according to the first embodiment. [Figure 9] FIG. 13(a) is a schematic enlarged view of an expanded portion provided in a first recess according to a second embodiment of the present invention, and FIG. 13(b) is a schematic enlarged view of an expanded portion provided in a second recess according to a second embodiment of the present invention. [Figure 10] 10(a) is a schematic enlarged view of an expanded portion provided in a first recess in accordance with a third embodiment of the present invention, and (b) is a schematic enlarged view of an expanded portion provided in a second recess in accordance with a third embodiment of the present invention. [Figure 11]FIG. 13(a) is a schematic enlarged view of an expanded portion provided in a first recess in accordance with a fourth embodiment of the present invention, and FIG. 13(b) is a schematic enlarged view of an expanded portion provided in a second recess in accordance with a fourth embodiment of the present invention. [Figure 12] FIG. 13(a) is a schematic enlarged view of an expanded portion provided in a first recess in accordance with a fifth embodiment of the present invention, and FIG. 13(b) is a schematic enlarged view of an expanded portion provided in a second recess in accordance with a fifth embodiment of the present invention. [Figure 13] FIG. 13 is a plan view of a piezoelectric vibrating piece according to a sixth embodiment of the present invention. [Figure 14] FIG. 13 is a schematic diagram showing an oscillator according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a piezoelectric vibrating piece and a piezoelectric vibrator according to the present invention will be described with reference to the drawings.

[0034] (First embodiment) (Piezoelectric vibrator) FIG. 1 is an external perspective view of a piezoelectric vibrator according to this embodiment. FIG. 2 is a plan view of the piezoelectric vibrator with the sealing plate removed. FIG. 3 is a cross-sectional view corresponding to line II in FIG. 2. FIG. 4 is an exploded perspective view of the piezoelectric vibrator according to this embodiment. As shown in FIGS. 1 to 4, the piezoelectric vibrator 1 is a so-called ceramic package type surface mount vibrator. The piezoelectric vibrator 1 includes a package 2 having a hermetically sealed cavity C therein, and a piezoelectric vibrating piece 3 housed in the cavity C. The piezoelectric vibrator 1 has a rectangular parallelepiped shape. In this embodiment, the longitudinal direction of the piezoelectric vibrator 1 in a plan view is referred to as the longitudinal direction L, the lateral direction is referred to as the width direction W, and the direction perpendicular to the longitudinal direction L and the width direction W is referred to as the thickness direction T.

[0035] The package 2 includes a package body 4 and a sealing plate 5 that is bonded to the package body 4 and forms a cavity C between the package body 4 and the sealing plate 5. The package body 4 includes a first base substrate 2a and a second base substrate 2b that are bonded together in a superimposed state, and a seal ring 2c that is bonded onto the second base substrate 2b.

[0036] The first base substrate 2a is a ceramic substrate having a rectangular shape in a plan view seen from the thickness direction T. The upper surface of the first base substrate 2a forms the bottom of the cavity C. A pair of external electrodes (external electrodes 2d and 2e) are formed on the lower surface of the first base substrate 2a with a gap in between in the longitudinal direction L. The external electrodes 2d and 2e are each formed of a single layer film made of a single metal formed by, for example, vapor deposition or sputtering, or a laminated film in which different metals are laminated.

[0037] The second base substrate 2b is a ceramic substrate having the same shape as the first base substrate 2a in a plan view, and is integrally bonded to the first base substrate 2a by sintering while being stacked on the first base substrate 2a. Note that the ceramic material used for the first base substrate 2a and the second base substrate 2b may be, for example, HTCC (High Temperature Co-Fired Ceramic) made of alumina or LTCC (Low Temperature Co-Fired Ceramic) made of glass ceramics.

[0038] As shown in Figs. 2 to 4, the second base substrate 2b has a through-hole 2f formed therein, which penetrates the second base substrate 2b in the thickness direction T. The through-hole 2f has a rounded rectangular shape in a plan view. On the inner surface of the through-hole 2f, mounting portions (mounting portion 2g and mounting portion 2h) protruding toward the inside in the width direction W are formed separately in portions located on both sides in the width direction W. The mounting portion 2g and mounting portion 2h are located in the center of the second base substrate 2b in the longitudinal direction L.

[0039] A pair of electrode pads (electrode pad 2i and electrode pad 2j) that are connection electrodes with the piezoelectric vibrating piece 3 are formed on the mounting portion 2g and the mounting portion 2h. The electrode pads 2i and 2j, like the external electrodes 2d and 2e described above, are made of a single-layer film of a single metal formed by, for example, vapor deposition or sputtering, or a laminated film in which different metals are laminated. The electrode pads 2i and 2j are electrically connected to the external electrodes 2d and 2e via through-wiring (not shown) that penetrates the first base substrate 2a and the second base substrate 2b in the thickness direction T.

[0040] At the four corners of the first base substrate 2a and the second base substrate 2b, a cutout portion 2k having a 1 / 4 circular arc shape in a plan view is formed over the entire thickness direction T of the first base substrate 2a and the second base substrate 2b. The first base substrate 2a and the second base substrate 2b are fabricated, for example, by stacking and bonding two ceramic substrates in the form of wafers, forming a plurality of through holes penetrating both ceramic substrates in a matrix pattern, and cutting both ceramic substrates in a lattice pattern using each through hole as a reference. At this time, the through holes are divided into four to form the above-mentioned cutout portion 2k.

[0041] The seal ring 2c is a conductive frame-shaped member that is slightly smaller than the outer shape of the first base substrate 2a and the second base substrate 2b, and is joined to the upper surface of the second base substrate 2b. Specifically, the seal ring 2c is joined to the second base substrate 2b by baking with a brazing material such as silver brazing or a solder material, or by welding to a metal bonding layer formed on the second base substrate 2b. The seal ring 2c constitutes the side wall of the cavity C together with the inner surface of the second base substrate 2b (the through portion 2f). In the illustrated example, the inner surface of the seal ring 2c is disposed flush with the inner surface of the second base substrate 2b.

[0042] The material of the seal ring 2c may be, for example, a nickel-based alloy, and may be selected from Kovar, Elinvar, Invar, 42-alloy, etc. In particular, it is preferable to select a material for the seal ring 2c that has a thermal expansion coefficient close to that of the first base substrate 2a and the second base substrate 2b, which are made of ceramics. For example, when alumina with a thermal expansion coefficient of 6.8×10-6 / °C is used as the first base substrate 2a and the second base substrate 2b, it is preferable to use Kovar with a thermal expansion coefficient of 5.2×10-6 / °C or 42-alloy with a thermal expansion coefficient of 4.5 to 6.5×10-6 / °C as the seal ring 2c.

[0043] The sealing plate 5 is made of a conductive substrate and is joined onto the seal ring 2c to airtightly seal the inside of the package body 4. The space defined by the seal ring 2c, the sealing plate 5, the first base substrate 2a, and the second base substrate 2b constitutes a hermetically sealed cavity C.

[0044] The piezoelectric vibrating piece 3 is accommodated in a cavity C of a hermetically sealed package 2. In this embodiment, the piezoelectric vibrating piece 3 includes a piezoelectric plate 30 formed of quartz crystal. The piezoelectric plate 30 has a pair of vibrating arms (a first vibrating arm 31 and a second vibrating arm 32) and a pair of supporting arms (a first supporting arm 33 and a second supporting arm 34). The piezoelectric vibrating piece 3 is mounted on the package 2 in the cavity C by the first supporting arm 33 being supported by the mounting portion 2g and the second supporting arm 34 being supported by the mounting portion 2h with a conductive adhesive. As a result, the piezoelectric vibrating piece 3 is supported in the cavity C with the first vibrating arm 31 and the second vibrating arm 32 floating above the first base substrate 2a. On the outer surfaces of the first vibrating arm 31 and the second vibrating arm 32, two systems of excitation electrodes (not shown) are arranged to vibrate the pair of the first vibrating arm 31 and the second vibrating arm 32 when a predetermined voltage is applied.

[0045] To operate the piezoelectric vibrator 1, a predetermined voltage is applied to the external electrodes 2d and 2e (see FIG. 1). Then, a current flows through the excitation electrodes, generating an electric field. The first vibrating arm 31 and the second vibrating arm 32 vibrate, for example, in a direction approaching or separating from each other (width direction W) at a predetermined resonance frequency due to the inverse piezoelectric effect caused by the electric field. The vibrations of the first vibrating arm 31 and the second vibrating arm 32 are used as a time source, a timing source for a control signal, a reference signal source, etc.

[0046] (Piezoelectric vibrating piece) 5 is a plan view of the piezoelectric vibrating reed according to the first embodiment. The piezoelectric vibrating reed 3 includes a piezoelectric plate 30 and an electrode film (not shown) arranged on the outer surface including the front and back surfaces of the piezoelectric plate 30. In this embodiment, the longitudinal direction L, width direction W, and thickness direction T of the piezoelectric vibrator 1 coincide with the longitudinal direction, width direction, and thickness direction of the piezoelectric vibrating reed 3, respectively. Therefore, in the following description of the piezoelectric vibrating reed 3, the longitudinal direction L, width direction W, and thickness direction T of the piezoelectric vibrator 1 are used.

[0047] The piezoelectric plate 30 includes the pair of vibrating arms (first vibrating arm 31 and second vibrating arm 32), a pair of supporting arms (first supporting arm 33 and second supporting arm 34), a base 35, and a widening section 36 (acute angle structure generation suppression function section). The first vibrating arm 31 and the second vibrating arm 32 are formed extending from the base 35 in the longitudinal direction L. The first supporting arm 33 and the second supporting arm 34 are located on both sides of the base 35 in the width direction W. The piezoelectric plate 30 is formed so that the planar shape seen from the thickness direction T is approximately symmetrical with respect to the central axis O along the longitudinal direction L. In this embodiment, the piezoelectric material forming the piezoelectric plate 30 is quartz crystal.

[0048] The first vibrating arm 31 and the second vibrating arm 32 are arranged in parallel in the width direction W, and each is connected to a base 35. The first vibrating arm 31 and the second vibrating arm 32 have their base ends on the base 35 side as fixed ends and their tips as free ends, and vibrate in a direction approaching or separating from each other (width direction W). The first vibrating arm 31 and the second vibrating arm 32 have a main body 37 extending from the base ends of the first vibrating arm 31 and the second vibrating arm 32 to the tips, and a weight 38 located at the tips of the first vibrating arm 31 and the second vibrating arm 32.

[0049] A groove 39 is formed in the main body 37. The groove 39 is recessed in the thickness direction T on both main surfaces of the main body 37 and extends along the longitudinal direction L. The groove 39 is formed from the vicinity of the base ends of the first vibrating arm 31 and the second vibrating arm 32 to the vicinity of the tip end of the main body 37.

[0050] The weights 38 each extend in the longitudinal direction L from a tip of the main body 37. The weights 38 are rectangular in plan view and are formed to be wider in the width direction W than the main body 37. This makes it possible to increase the mass of the tips of the first vibrating arm 31 and the second vibrating arm 32 and the moment of inertia during vibration, and to reduce the length of the first vibrating arm 31 and the second vibrating arm 32 compared to a piezoelectric vibrating piece 3 that does not have the weights 38.

[0051] The first support arm 33 and the second support arm 34 are L-shaped in plan view and surround the base 35, the first vibrating arm 31 (main body 37), and the second vibrating arm 32 (main body 37) from the outside in the width direction W. Specifically, the first support arm 33 and the second support arm 34 have a connection portion 40 protruding from both end faces in the width direction W of the base 35 toward the outside in the width direction W, and a longitudinal extension portion 41 extending from the outer end face in the width direction W of the connection portion 40 along the longitudinal direction L. The longitudinal extension portion 41 extends in parallel with the first vibrating arm 31 and the second vibrating arm 32. The first support arm 33 is disposed on the same side as the first vibrating arm 31 with respect to the central axis O. The second support arm 34 is disposed on the same side as the second vibrating arm 32 with respect to the central axis O.

[0052] 5, the piezoelectric plate 30 is provided with a plurality of recesses when viewed from the thickness direction T. For example, in this embodiment, a first recess 50 formed by the first supporting arm 33, the base 35, and the first vibrating arm 31 is provided. In addition, a second recess 51 formed by the second supporting arm 34, the base 35, and the second vibrating arm 32 is provided.

[0053] The first recess 50 is a recess formed by being surrounded by the side surface 41a of the longitudinal extension portion 41 of the first supporting arm portion 33, the side surface 40a of the connection portion 40 of the first supporting arm portion 33, the side surface 35a of the base portion 35, and the side surface 31a of the first vibrating arm portion 31. The second recess 51 is a recess formed by being surrounded by the side surface 41a of the longitudinal extension portion 41 of the second supporting arm portion 34, the side surface 40a of the connection portion 40 of the second supporting arm portion 34, the side surface 35a of the base portion 35, and the side surface 32a of the second vibrating arm portion 32.

[0054] The widened portion 36 is provided in the first recess 50 and the second recess 51, and suppresses the occurrence of an acute angle structure X1 (see FIG. 7(b)) formed by an etching residue X (see FIG. 7) in the first recess 50 and the second recess 51. The etching residue X and the acute angle structure X1 will be described in more detail later.

[0055] If the widening portion 36 is not provided in the first recess 50, a corner C1 formed by connecting the side surface 41a of the longitudinally extending portion 41 of the first support arm portion 33 and the side surface 40a of the connecting portion 40 of the first support arm portion 33 is exposed. The widening portion 36 provided in the first recess 50 is provided in the first recess 50 so as to embed the corner C1.

[0056] The widening portion 36 provided in the first recess 50 has an inclined surface 36a connected to the side surface 41a of the longitudinal extension portion 41 of the first support arm portion 33 and the side surface 40a of the connection portion 40 of the first support arm portion 33. The inclined surface 36a of the widening portion 36 provided in the first recess 50 is inclined with respect to both the side surface 41a of the longitudinal extension portion 41 of the first support arm portion 33 and the side surface 40a of the connection portion 40 of the first support arm portion 33, as shown in FIG.

[0057] If the widening portion 36 is not provided in the second recess 51, the corner C2 formed by connecting the side surface 35a of the base portion 35 and the side surface 40a of the connecting portion 40 of the second support arm portion 34 is exposed. The widening portion 36 provided in the second recess 51 is provided in the second recess 51 so as to embed the corner C2.

[0058] The widening portion 36 provided in the second recess 51 has an inclined surface 36a connected to the side surface 35a of the base 35 and the side surface 40a of the connection portion 40 of the second support arm portion 34. The inclined surface 36a of the widening portion 36 provided in the second recess 51 is inclined with respect to both the side surface 35a of the base 35 and the side surface 40a of the connection portion 40 of the second support arm portion 34, as shown in FIG.

[0059] Fig. 6 is a cross-sectional view corresponding to line II-II in Fig. 5. As shown in Fig. 6, the dimension in the thickness direction T of the base 35 (thickness dimension 35D) is the same as the dimension in the thickness direction T of the first support arm 33 (thickness dimension 33D) and the dimension in the thickness direction T of the second support arm 34 (thickness dimension 34D). The upper surface of the base 35, the upper surface of the first support arm 33, and the upper surface of the second support arm 34 are arranged to be flush with each other. In addition, the lower surface of the base 35, the lower surface of the first support arm 33, and the lower surface of the second support arm 34 are arranged to be flush with each other.

[0060] The dimension (thickness dimension 36D) of the widening portion 36 in the thickness direction T is also the same as the thickness dimension 35D of the base 35. That is, the thickness dimension 36D of the widening portion 36 is also the same as the thickness dimension 33D of the first support arm portion 33 and the thickness dimension 34D of the second support arm portion 34. In addition, the upper surface of the widening portion 36 is arranged flush with the upper surface of the base 35. That is, the upper surface of the widening portion 36 is also arranged flush with the upper surface of the first support arm portion 33 and the upper surface of the second support arm portion 34. In addition, the lower surface of the widening portion 36 is arranged flush with the lower surface of the base 35. That is, the lower surface of the widening portion 36 is also arranged flush with the lower surface of the first support arm portion 33 and the lower surface of the second support arm portion 34.

[0061] Here, the relationship between the shape of the piezoelectric plate 30 and the crystal axis of the quartz crystal, which is the material for forming the piezoelectric plate 30, will be described. For example, the electric axis of the quartz crystal is the X axis, the mechanical axis is the Y axis, and the optical axis is the Z axis. In a coordinate system in which the X axis, Y axis, and Z axis are orthogonal to each other, a new axis obtained by rotating the Z axis around the X axis within a range of -5° to +10° is the Z' axis, and a new axis obtained by rotating the Y axis at the same angle as the Z axis in a plane including the Z axis and the Y axis with the X axis as the rotation axis is the Y' axis, and a coordinate system in which the X axis, Y' axis, and Z' axis are orthogonal to each other is a new orthogonal coordinate system. In this embodiment, the X axis coincides with the width direction W shown in FIG. 5 and the like, the Y' axis coincides with the longitudinal direction L shown in FIG. 5 and the like, and the Z' axis coincides with the thickness direction T shown in FIG. 5 and the like. In other words, when viewed in a plane from the Z' axis, the first vibrating arm 31, the second vibrating arm 32, the first supporting arm 33 and the second supporting arm 34 are arranged extending from the base 35 along a plane including the X-axis and the Y'-axis.

[0062] That is, in a coordinate system in which the electric axis of a quartz crystal is the X axis, the mechanical axis is the Y axis, and the optical axis is the Z axis, a new axis obtained by rotating the Z axis around the X axis within a range of -5° to +10° is defined as the Z' axis, and a new axis obtained by rotating the Y axis at the same angle as the Z axis in a plane including the Z axis and the Y axis with the X axis as the rotation axis is defined as the Y' axis. In this embodiment, in a planar view from the Z' axis, the first vibrating arm 31, the second vibrating arm 32, the first supporting arm 33, and the second supporting arm 34 are arranged to extend from the base 35 along a plane including the X-axis-Y' axis in an orthogonal coordinate system consisting of the X axis, Y' axis, and Z' axis.

[0063] FIG. 7(a) is a schematic enlarged view including the first recess 50 of the piezoelectric plate 30 of this embodiment. FIG. 7(b) is a schematic enlarged view of the first recess 50 when the widened portion 36 is not provided. When the piezoelectric plate 30 is shaped by wet etching as described below, an etching residue X is generated on the side surface of the piezoelectric plate 30, as shown in FIG. 7(a) and FIG. 7(b). This etching residue X is a portion that protrudes from the outer shape of the mask used in the wet etching when viewed from the Z′-axis direction, and is an etching residue generated due to the characteristics of quartz. The shape of this etching residue X is determined depending on the direction of the crystal axis of the quartz.

[0064] For example, as shown in FIG. 7(b), when the widened portion 36 is not provided in the first recess 50, a large amount of etching residue X is generated on the side surface 33a of the longitudinal extension portion 41 of the first support arm 33 on the first vibrating arm 31 side and the side surface 33a of the connection portion 40 of the first support arm 33 on the inner wall side of the first recess 50. As a result, an acute angle structure X1 is formed in the vicinity of the corner C1. This acute angle structure X1 is a structure formed by the etching residue X, and is a crack-like structure that narrows from the surface of the etching residue X toward the back as viewed from the thickness direction T. In particular, a crack-like structure formed by the etching residue X, in which the angle of the back as viewed from the thickness direction T is smaller than 90°, is called the acute angle structure X1. Such an acute angle structure X1 is a location where stress concentration occurs due to the transmission of vibration of the first vibrating arm 31, and may become the starting point of a crack generated in the piezoelectric plate 30. Note that the etching residue X is omitted in the drawings other than FIG. 7.

[0065] On the other hand, as shown in Fig. 7(a), in the piezoelectric vibrating piece 3 of this embodiment, the widened portion 36 is provided so as to fill the position where the acute angle structure X1 shown in Fig. 7(b) is formed. Therefore, according to the piezoelectric vibrating piece 3 of this embodiment, it is possible to suppress the occurrence of the acute angle structure X1 that may cause damage to the piezoelectric plate 30, i.e., the piezoelectric vibrating piece 3.

[0066] In the above-mentioned Cartesian coordinate system in which the X-axis, Y'-axis, and Z'-axis are perpendicular to each other, the widening portion 36 provided in the first recess 50 bulges out from the corner C1 in a direction along a plane including the X-axis and Y'-axis. For example, the widening portion 36 provided in the first recess 50 is provided so that the inclined surface 36a is perpendicular to the widening direction P obtained by rotating the X-axis around the Z'-axis by 15° to 50° clockwise in a plan view.

[0067] Furthermore, if the widened portion 36 is not provided in the second recess 51, a large amount of etching residue X is generated on the side surface 40a on the inner wall side of the connection portion 40 of the second support arm 34 and the side surface 35a on the second support arm 34 side of the base portion 35. As a result, an acute angle structure (not shown) similar to the acute angle structure X1 shown in FIG. 7(a) is formed in the vicinity of the corner C2. In contrast, in the piezoelectric vibrating piece 3 of this embodiment, the widened portion 36 is also provided in the second recess 51 so as to fill the position where the acute angle structure is formed. Therefore, according to the piezoelectric vibrating piece 3 of this embodiment, it is possible to suppress the occurrence of an acute angle structure in the second recess 51, which may cause damage to the piezoelectric plate 30, i.e., the piezoelectric vibrating piece 3.

[0068] In the above-mentioned Cartesian coordinate system in which the X-axis, Y'-axis, and Z'-axis are perpendicular to each other, the widening portion 36 provided in the second recess 51 bulges out from the corner C2 in a direction along a plane including the X-axis and Y'-axis. For example, the widening portion 36 provided in the second recess 51 is provided so that the inclined surface 36a is perpendicular to the widening direction P obtained by rotating the X-axis around the Z'-axis by 15° to 50° clockwise in a plan view.

[0069] The electrode film is, for example, a laminated film of chromium (Cr) and gold (Au), which is formed by depositing a thin film of gold on a chromium film that has good adhesion to quartz crystal. However, the film configuration of the electrode film is not limited to this, and for example, a thin film of gold may be further laminated on a laminated film of chromium and nichrome (NiCr), or a single layer film of chromium, nickel, aluminum (Al), titanium (Ti), etc. may be used.

[0070] The electrode film includes excitation electrodes provided on the first vibrating arm portion 31 and the second vibrating arm portion 32, mount electrodes that serve as mount portions when the first support arm portion 33 and the second support arm portion 34 are mounted on the package 2, and connection wiring that connects the excitation electrodes and the mount electrodes.

[0071] (Manufacturing method of piezoelectric vibrating piece) Next, a method for manufacturing the piezoelectric vibrating reed 3 will be described. Fig. 8 is a flowchart showing a method for manufacturing the piezoelectric vibrating reed according to the first embodiment. As shown in Fig. 8, the method for manufacturing the piezoelectric vibrating reed 3 according to the first embodiment includes an outer shape forming process S10, an electrode film forming process S20, and a singulation process S30.

[0072] First, the outer shape forming process S10 is performed. In the outer shape forming process S10, the piezoelectric plate 30 is formed on the crystal wafer. First, a mask having a shape corresponding to the planar shape of the piezoelectric plate 30 is formed on both sides of the crystal wafer by photolithography technology. Next, the crystal wafer is wet etched. As a result, the unmasked areas of the crystal wafer are selectively removed, and the wafer is shaped into the planar shape of the piezoelectric plate 30.

[0073] Here, in the manufacturing method of the piezoelectric vibrating piece 3 of this embodiment, the outer shapes of the first vibrating arm portion 31, the second vibrating arm portion 32, the first supporting arm portion 33, the second supporting arm portion 34, and the base portion 35 are formed by photolithography technology, and the outer shape of the widened portion 36 is also formed at the same time. Specifically, a mask is shaped to cover the area where the widened portion 36 is to be formed. By performing wet etching using such a mask, the outer shapes of the first vibrating arm portion 31, the second vibrating arm portion 32, the first supporting arm portion 33, the second supporting arm portion 34, and the base portion 35 are formed by photolithography technology, and the outer shape of the widened portion 36 is also formed at the same time.

[0074] Next, grooves 39 are formed on both main surfaces (front and back) of the first vibrating arm 31 and the second vibrating arm 32. Specifically, a mask having a shape corresponding to the shape of the grooves 39 is formed on both main surfaces of the quartz wafer by photolithography. Next, half-etching is performed on the quartz wafer by wet etching to the extent that the grooves 39 do not penetrate the quartz wafer. As a result, a piezoelectric plate 30 having the grooves 39 is formed on the wafer.

[0075] Next, an electrode film forming step S20 is performed. In the electrode film forming step S20, an electrode film is disposed on the front and rear surfaces of the piezoelectric plate 30. The electrode film forming step S20 includes an electrode film forming step of forming an electrode film, and a patterning step of patterning the electrode film to form excitation electrodes and the like.

[0076] In the electrode film forming process, an electrode film is formed on the front and rear surfaces and end faces of the quartz crystal wafer by sputtering, deposition, or the like. In the patterning process, the electrode film is patterned to form two systems of excitation electrodes, etc. on the piezoelectric plate 30. First, a mask made of a resist material having a shape corresponding to the outer shape of the excitation electrodes, etc. is formed on the outer surface of the electrode film by photolithography technology. Next, the electrode film is etched to selectively remove the electrode film in the unmasked areas. As a result, excitation electrodes, mount electrodes, and connection wiring are formed on the piezoelectric plate 30.

[0077] Through the outline forming step S10 and the electrode film forming step S20, a plurality of piezoelectric vibrating pieces 3 are formed on a single crystal wafer.

[0078] Next, the singulation process S30 is performed. In the singulation process S30, the piezoelectric vibrating pieces 3 are separated from the quartz crystal wafer. Specifically, the piezoelectric vibrating pieces 3 are pushed into or pulled up from the quartz crystal wafer, causing relative displacement in the thickness direction T between the connecting parts provided on the quartz crystal wafer and the piezoelectric vibrating pieces 3. As a result, the piezoelectric vibrating pieces 3 are separated from the connecting parts and singulated. As a result, multiple piezoelectric vibrating pieces 3 are formed from one quartz crystal wafer.

[0079] The piezoelectric vibrating piece 3 of the present embodiment as described above includes a piezoelectric plate 30 made of quartz, and the piezoelectric plate 30 includes a base 35 and a pair of a first vibrating arm 31 and a second vibrating arm 32 connected to the base 35. The piezoelectric vibrating piece 3 of the present embodiment also includes a first support arm 33 and a second support arm 34 connected to the base 35. The piezoelectric plate 30 is also made of quartz. The piezoelectric vibrating piece 3 of the present embodiment also includes a first recess 50 and a second recess 51 formed by one or more of the base 35, the first vibrating arm 31, the second vibrating arm 32, the first support arm 33, and the second support arm 34. The piezoelectric vibrating piece 3 further includes a widened portion 36 as an acute angle structure generation suppression functional portion that is provided in the first recess 50 and the second recess 51 and suppresses the generation of an acute angle structure X1 formed by the etching residue X of the first recess 50 and the second recess 51 when viewed from the thickness direction (thickness direction T) of the base 35.

[0080] The shape of the etching residue X in the piezoelectric plate 30 made of quartz crystal is determined depending on the direction of the crystal axis. In other words, when piezoelectric plates 30 having the same crystal axis direction are formed, etching residues X of the same shape are generated. Therefore, the shape of the etching residue X generated in the piezoelectric plate 30 can be predicted in advance, and the shape and position of the acute angle structure X1 formed by such etching residue X can also be predicted.

[0081] In the piezoelectric vibrating piece 3 of this embodiment, the widening portion 36 is provided to suppress the occurrence of the acute angle structure X1 in the etching residue X whose shape and position can be predicted in advance. The widening portion 36 is provided in the narrow first recess 50 and the narrow second recess 51 formed by one or more of the base 35, the first vibrating arm 31 and the second vibrating arm 32, and the first supporting arm 33 and the second supporting arm 34. Although the acute angle structure X1 due to the etching residue X is likely to occur in such narrow first recess 50 and the narrow second recess 51, the piezoelectric vibrating piece 3 of this embodiment can suppress the occurrence of the acute angle structure X1 in the first recess 50 and the narrow second recess 51 by the widening portion 36 compared to the case where the widening portion 36 is not provided. Therefore, the piezoelectric vibrating piece 3 of this embodiment can suppress the piezoelectric vibrating piece 3 from being damaged by the acute angle structure X1 formed by the etching residue X in the piezoelectric vibrating piece 3 having the piezoelectric plate 30 formed of quartz.

[0082] In addition, in the piezoelectric vibrating piece 3 of this embodiment, the first recess 50 and the second recess 51 have corners C1 and C2 formed by one or more of the base 35, the first supporting arm 33, and the second supporting arm 34. In addition, in the piezoelectric vibrating piece 3 of this embodiment, the acute angle structure generation suppression functional portion is the widened portion 36 provided by embedding the corners C1 and C2.

[0083] According to the piezoelectric vibrating piece 3 of this embodiment, it is possible to improve the strength of the piezoelectric vibrating piece 3 compared to a case where the acute angle structure occurrence suppression functional portion is a groove portion, etc. Therefore, according to the piezoelectric vibrating piece 3 of this embodiment, it is possible to more reliably prevent the piezoelectric vibrating piece 3 from being damaged.

[0084] In addition, in the piezoelectric vibrating piece 3 of this embodiment, the thickness dimension 36D of the widened portion 36 is at least the same as that of the base portion 35. Therefore, in the manufacturing process, the widened portion 36 can be formed at the same time as the base portion 35 is formed by etching, and there is no need to perform post-processing on the widened portion 36 after the base portion 35 is formed. Therefore, the widened portion 36 can be easily formed.

[0085] In the piezoelectric vibrating piece 3 of this embodiment, the widening portion 36 has an inclined surface 36a inclined with respect to the first side surface and the second side surface forming the corner. For example, the inclined surface 36a of the widening portion 36 provided in the first recess 50 is inclined and connected with respect to the side surface 41a (first side surface) of the longitudinally extending portion 41 of the first supporting arm portion 33 forming the corner C1 and the side surface 40a (second side surface) of the connecting portion 40 of the first supporting arm portion 33. In addition, the inclined surface 36a of the widening portion 36 provided in the second recess 51 is inclined and connected with respect to the side surface 35a (first side surface) of the base portion 35 forming the corner C2 and the side surface 40a (second side surface) of the connecting portion 40 of the second supporting arm portion 34.

[0086] According to the piezoelectric vibrating piece 3 of this embodiment, the connection angle between the side surface of the widening portion 36 and the inner wall surfaces of the first recess 50 and the second recess 51 can be made shallow, making it possible to prevent the occurrence of an acute angle structure X1 due to etching residue X at the boundary portion between the widening portion 36 and the inner wall surfaces of the first recess 50 and the second recess 51.

[0087] Furthermore, the piezoelectric vibrating reed 3 of this embodiment has two first supporting arms 33 and two second supporting arms 34 arranged parallel to the pair of first vibrating arms 31 and second vibrating arms 32, sandwiching the pair of first vibrating arms 31 and second vibrating arms 32 therebetween. Such a piezoelectric vibrating reed 3 of this embodiment is a so-called side arm type piezoelectric vibrating reed. Therefore, the piezoelectric vibrating reed 3 of this embodiment is a side arm type piezoelectric vibrating reed that can prevent the piezoelectric vibrating reed 3 from being damaged by the acute angle structure X1 formed by the etching residue X.

[0088] In addition, in the piezoelectric vibrating reed 3 of this embodiment, in a coordinate system in which the electric axis of the crystal is the X axis, the mechanical axis is the Y axis, and the optical axis is the Z axis, a new axis obtained by rotating the Z axis around the X axis within a range of -5° to +10° is defined as the Z' axis, and a new axis obtained by rotating the Y axis at the same angle as the Z axis in a plane including the Z axis and the Y axis with the X axis as the rotation axis is defined as the Y' axis. In this case, in a rectangular coordinate system consisting of the X axis, Y' axis, and Z' axis, when viewed in a plane from the Z' axis, the first vibrating arm 31 and the second vibrating arm 32 and the first supporting arm 33 and the second supporting arm 34 are extended from the base 35 along a plane including the X axis-Y' axis.

[0089] In the piezoelectric vibrating piece 3 in which the first vibrating arm 31, the second vibrating arm 32, and the first supporting arm 33, and the second supporting arm 34 are provided extending from the base 35 along a plane including the X-axis-Y'-axis as described above, an acute angle structure X1 due to the etching residue X is likely to occur in the first recess 50 and the second recess 51. According to the piezoelectric vibrating piece 3 of this embodiment, even though the acute angle structure X1 due to the etching residue X is likely to occur in the first recess 50 and the second recess 51, the provision of the widened portion 36 makes it possible to effectively prevent the piezoelectric vibrating piece 3 from being damaged.

[0090] Moreover, the piezoelectric vibrator 1 of this embodiment includes a piezoelectric vibrating piece 3 and a package 2 that hermetically seals the piezoelectric vibrating piece 3 and in which the piezoelectric vibrating piece 3 is mounted via a first supporting arm 33 and a second supporting arm 34. Therefore, the piezoelectric vibrator 1 of this embodiment is a piezoelectric vibrator 1 that can prevent damage to the piezoelectric vibrating piece 3 caused by the acute angle structure X1 due to the etching residue X, and has high reliability.

[0091] Second embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 9. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0092] In the piezoelectric vibrating piece 3 of the first embodiment, the widened portion 36 has a single inclined surface 36a with a constant inclination angle. In contrast, in this embodiment, the widened portion 60 has a plurality of inclined surfaces 60a (two in this embodiment) with different angles relative to the side surface forming the corner portion.

[0093] 9(a) is a schematic enlarged view of the widening portion 60 provided in the first recess 50. As shown in this figure, the widening portion 60 provided in the first recess 50 is provided such that two inclined surfaces 60a with different angles connect the side surface 41a of the longitudinal extension portion 41 of the first support arm portion 33 and the side surface 40a of the connection portion 40 of the first support arm portion 33. In the widening portion 60 provided in the first recess 50, the angles of the respective inclined surfaces 60a with respect to the side surface 41a of the longitudinal extension portion 41 of the first support arm portion 33 (the side surface 40a of the connection portion 40 of the first support arm portion 33) are different.

[0094] The inclination angle of the inclined surface 60a located on the side surface 41a of the longitudinal extension 41 of the first support arm 33 with respect to the side surface 41a is smaller than the inclination angle of the inclined surface 60a located on the side surface 40a of the connection portion 40 of the first support arm 33 with respect to the side surface 41a. That is, among the multiple inclined surfaces 60a of the widening portion 60 provided in such a first recess 50, the inclination angle of the inclined surface 60a located closest to the side surface 41a of the longitudinal extension 41 of the first support arm 33 with respect to the side surface 41a is the smallest compared to the inclination angles of the other inclined surfaces 60a with respect to the side surface 41a.

[0095] Moreover, the inclination angle of the inclined surface 60a located on the side surface 40a of the connection portion 40 of the first support arm portion 33 with respect to the side surface 40a is smaller than the inclination angle of the inclined surface 60a located on the side surface 41a of the longitudinal extension portion 41 of the first support arm portion 33 with respect to the side surface 40a. That is, among the multiple inclined surfaces 60a of the widening portion 60 provided in such a first recess 50, the inclination angle of the inclined surface 60a located closest to the side surface 40a of the connection portion 40 of the first support arm portion 33 with respect to the side surface 40a is the smallest with respect to the inclination angles of the other inclined surfaces with respect to the side surface 40a.

[0096] For example, the angle of the normal to the inclined surface 60a located on the side 41a of the longitudinal extension 41 of the first support arm 33 with respect to the X-axis is set to 7.5° to 25°, and the angle of the normal to the inclined surface 60a located on the side 40a of the connection portion 40 of the first support arm 33 with respect to the X-axis is set to twice the angle of the normal to the inclined surface 60a located on the side 41a of the longitudinal extension 41 of the first support arm 33 with respect to the X-axis.

[0097] 9(b) is a schematic enlarged view of the widening portion 60 provided in the second recess 51. As shown in this figure, the widening portion 60 provided in the second recess 51 has two inclined surfaces 60a with different angles that connect the side surface 35a of the base 35 and the side surface 40a of the connection portion 40 of the second support arm 34. In the widening portion 60 provided in the second recess 51, the angles of the respective inclined surfaces 60a with respect to the side surface 35a of the base 35 (the side surface 40a of the connection portion 40 of the second support arm 34) are different.

[0098] The inclination angle of the inclined surface 60a located on the side of the side 35a of the base 35 with respect to the side 35a is smallest relative to the inclination angle of the inclined surface 60a located on the side of the side 40a of the connection portion 40 of the second support arm portion 34 with respect to the side 35a. In other words, among the multiple inclined surfaces 60a of the widening portion 60 provided in such a second recess 51, the inclination angle of the inclined surface 60a located closest to the side of the side 35a of the base 35 with respect to the side 35a is smallest relative to the inclination angles of the other inclined surfaces 60a with respect to the side 35a.

[0099] Furthermore, the inclination angle of the inclined surface 60a located on the side surface 40a of the connecting portion 40 of the second supporting arm portion 34 with respect to the side surface 40a is the smallest relative to the inclination angle of the inclined surface 60a located on the side surface 35a of the base portion 35 with respect to the side surface 40a. That is, among the multiple inclined surfaces 60a of the widening portion 60 provided in such a second recess 51, the inclination angle of the inclined surface 60a located closest to the side surface 40a of the connecting portion 40 of the second supporting arm portion 34 with respect to the side surface 40a is the smallest relative to the inclination angles of the other inclined surfaces with respect to the side surface 40a.

[0100] For example, the angle of the normal to the inclined surface 60a located on the side 35a of the base 35 with respect to the X-axis is set to 7.5° to 25°, and the angle of the normal to the inclined surface 60a located on the side 40a of the connection portion 40 of the second support arm 34 with respect to the X-axis is set to twice the angle of the normal to the inclined surface 60a located on the side 35a of the base 35 with respect to the X-axis.

[0101] According to the piezoelectric vibrating piece 3 of this embodiment, the connection angle between the side surface of the widening portion 60 and the inner wall surfaces of the first recess 50 and the second recess 51 can be made shallower than when the widening portion 60 has a single inclined surface, and it is possible to better prevent the occurrence of an acute angle structure X1 due to etching residue X at the boundary portion between the widening portion 60 and the inner wall surfaces of the first recess 50 and the second recess 51.

[0102] In the present embodiment, the widening portion 60 has two inclined surfaces 60a. However, the present invention is not limited to this. It is also possible to adopt a configuration in which the widening portion 60 has three or more inclined surfaces 60a.

[0103] Third embodiment Next, a third embodiment of the present invention will be described with reference to Fig. 10. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0104] In the piezoelectric vibrating piece 3 of the first embodiment, the widened portion 36 has an inclined surface 36a. In contrast, in the present embodiment, the widened portion 61 has a corner and a curved surface 61a that is recessed toward the corner when viewed from the thickness direction T.

[0105] 10(a) is a schematic enlarged view of the widening portion 61 provided in the first recess 50. As shown in this figure, the widening portion 61 provided in the first recess 50 is provided such that a curved surface 61a whose center is recessed toward the corner C1 connects the side surface 41a of the longitudinal extension portion 41 of the first support arm portion 33 and the side surface 40a of the connection portion 40 of the first support arm portion 33. In this embodiment, the curvature of the curved surface 61a of the widening portion 61 provided in the first recess 50 is constant from the side surface 41a of the longitudinal extension portion 41 of the first support arm portion 33 to the side surface 40a of the connection portion 40 of the first support arm portion 33.

[0106] 10(b) is a schematic enlarged view of the widening portion 61 provided in the second recess 51. As shown in this figure, the widening portion 61 provided in the second recess 51 is provided such that a curved surface 61a whose center is recessed toward the corner C2 connects the side surface 35a of the base 35 and the side surface 40a of the connection portion 40 of the second support arm 34. In this embodiment, the curvature of the curved surface 61a of the widening portion 61 provided in the second recess 51 is constant from the side surface 35a of the base 35 to the side surface 40a of the connection portion 40 of the second support arm 34.

[0107] According to the piezoelectric vibrating piece 3 of this embodiment, the connection angle between the side surface of the widening portion 60 and the inner wall surfaces of the first recess 50 and the second recess 51 can be made shallow, making it possible to prevent the occurrence of an acute angle structure X1 due to etching residue X at the boundary portion between the widening portion 60 and the inner wall surfaces of the first recess 50 and the second recess 51.

[0108] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to Fig. 11. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0109] In the piezoelectric vibrating piece 3 of the first embodiment, the widened portion 36 has an inclined surface 36a. In contrast, in the present embodiment, the widened portion 62 has a corner and a curved surface 62a that is recessed toward the corner when viewed from the thickness direction T.

[0110] 11(a) is a schematic enlarged view of the widening portion 62 provided in the first recess 50. As shown in this figure, the widening portion 62 provided in the first recess 50 is provided such that a curved surface 62a whose center is recessed toward the corner C1 connects the side surface 41a of the longitudinally extending portion 41 of the first support arm portion 33 and the side surface 40a of the connection portion 40 of the first support arm portion 33.

[0111] In this embodiment, the curvature of the curved surface 62a of the widening portion 62 provided in the first recess 50 changes so that the angle between the tangent of the curved surface 62a and the side surface 41a becomes smaller as the curved surface 62a moves from the center as viewed in the thickness direction T toward the side surface 41a of the longitudinal extension portion 41 of the first support arm portion 33. Also, the curvature of the curved surface 62a of the widening portion 62 provided in the first recess 50 changes so that the angle between the tangent of the curved surface 62a and the side surface 40a becomes smaller as the curved surface 62a moves from the center as viewed in the thickness direction T toward the side surface 40a of the connection portion 40 of the first support arm portion 33. In this way, the curvature of the curved surface 62a of the widening portion 62 provided in the first recess 50 changes depending on the position of the curved surface 62a.

[0112] 11(b) is a schematic enlarged view of the widened portion 62 provided in the second recess 51. As shown in this figure, the widened portion 62 provided in the second recess 51 is provided so that a curved surface 62a whose center is recessed toward the corner C2 connects the side surface 35a of the base 35 and the side surface 40a of the connection portion 40 of the second support arm portion 34.

[0113] In this embodiment, the curvature of the curved surface 62a of the widening portion 62 provided in the second recess 51 changes so that the angle between the tangent of the curved surface 62a and the side surface 35a becomes smaller as the curved surface 62a moves from the center as viewed in the thickness direction T toward the side surface 35a of the base portion 35. Also, the curvature of the curved surface 62a of the widening portion 62 provided in the second recess 51 changes so that the angle between the tangent of the curved surface 62a and the side surface 40a becomes smaller as the curved surface 62a moves from the center as viewed in the thickness direction T toward the side surface 40a of the connection portion 40 of the second support arm portion 34. In this way, the curvature of the curved surface 62a of the widening portion 62 provided in the second recess 51 changes depending on the position of the curved surface 62a.

[0114] According to the piezoelectric vibrating piece 3 of this embodiment, the connection angle between the side surface of the widening portion 62 and the inner wall surfaces of the first recess 50 and the second recess 51 can be made shallower than when the curvature of the curved surface 62a of the widening portion 62 is constant, and it is possible to more effectively prevent the occurrence of an acute angle structure X1 due to etching residue X at the boundary portion between the widening portion 62 and the inner wall surfaces of the first recess 50 and the second recess 51.

[0115] Fifth embodiment Next, a fifth embodiment of the present invention will be described with reference to Fig. 12. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0116] In the piezoelectric vibrating piece 3 of the first embodiment, the widened portion 36 provided in the first recess 50 and the widened portion 36 provided in the second recess 51 have shapes that are asymmetric with respect to the central axis O when viewed in the thickness direction T. In contrast, in the present embodiment, the widened portion 63 provided in the first recess 50 and the widened portion 63 provided in the second recess 51 have shapes that are symmetric with respect to the central axis O when viewed in the thickness direction T.

[0117] 12(a) is a schematic enlarged view of the widened portion 63 provided in the first recess 50. As shown in this figure, the widened portion 63 provided in the first recess 50 has a curved surface 63a that connects the side surface 33a of the first supporting arm 33 and the side surface 31a of the first vibrating arm 31.

[0118] 12A, the amount by which the widened portion 63 provided in the first recess 50 protrudes from the base 35 at the portion on the first vibrating arm 31 side is smaller than the amount by which the widened portion 63 protrudes from the base 35 at the portion on the first supporting arm 33 side by a distance Da shown in FIG. 12A. In other words, compared to the case where the amount by which the portion on the first vibrating arm 31 side protrudes from the base 35 at the portion on the first supporting arm 33 side is the same as the amount by which the portion on the first supporting arm 33 side protrudes from the base 35, the contact area between the first vibrating arm 31 and the widened portion 63 in this embodiment is smaller.

[0119] 12(b) is a schematic enlarged view of the widened portion 63 provided in the second recess 51. As shown in this figure, the widened portion 63 provided in the second recess 51 has a curved surface 63a that connects the side surface 34a of the second supporting arm 34 and the side surface 32a of the second vibrating arm 32.

[0120] 12B, the amount by which the portion of the widened portion 63 provided in the second recess 51 protrudes from the base 35 at the second vibrating arm 32 side is smaller than the amount by which the portion of the portion of the portion of the second supporting arm 34 protrudes from the base 35 at the second supporting arm 34 side. In other words, the contact area between the second vibrating arm 32 and the widened portion 63 in this embodiment is smaller than when the amount by which the portion of the portion of the second vibrating arm 32 protrudes from the base 35 at the second supporting arm 34 side is the same as the amount by which the portion of the portion of the second supporting arm 34 protrudes from the base 35 at the second supporting arm 34 side.

[0121] The widened portion 63 provided in the first recess 50 and the widened portion 63 provided in the second recess 51 are formed symmetrically about the central axis O (see FIG. 5). In the piezoelectric vibrating piece 3 of this embodiment, the shape of the piezoelectric plate 30 is formed symmetrically including the widened portion 63, so that it is possible to equalize the weight balance between the first vibrating arm portion 31 and the second vibrating arm portion 32.

[0122] Moreover, according to the piezoelectric vibrating reed 3 of this embodiment, the contact area of ​​the widened portion 63 provided in the first recess 50 with the first vibrating arm 31 can be reduced, and made smaller than the contact area of ​​the first supporting arm 33 with the widened portion 63. Moreover, the contact area of ​​the widened portion 63 provided in the second recess 51 with the second vibrating arm 32 can be reduced, and made smaller than the contact area of ​​the second supporting arm 34 with the widened portion 63. Therefore, the influence of the widened portion 63 on the vibration of the first vibrating arm 31 and the second vibrating arm 32 can be reduced, and it is possible to prevent the widened portion 63 from affecting the vibration characteristics of the piezoelectric vibrating reed 3.

[0123] Sixth embodiment Next, a sixth embodiment of the present invention will be described with reference to Fig. 13. In the description of this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

[0124] The piezoelectric vibrating piece 3 of the first embodiment is a so-called side arm type piezoelectric vibrating piece. In contrast, the piezoelectric vibrating piece 3A of the present embodiment is a so-called center arm type piezoelectric vibrating piece.

[0125] Fig. 13 is a plan view of the piezoelectric vibrating reed of the sixth embodiment. As shown in this figure, the piezoelectric vibrating reed 3A of this embodiment has a single supporting arm 33A disposed between a pair of a first vibrating arm 31A and a second vibrating arm 32A. As shown in Fig. 13, the piezoelectric vibrating reed 3A of this embodiment has a first recess 50A formed by the first vibrating arm 31A, the supporting arm 33A, and a base 35.

[0126] Moreover, the piezoelectric vibrating piece 3A of this embodiment has a second recess 51A formed by the second vibrating arm portion 32A, the supporting arm portion 33A, and the base portion 35. The piezoelectric vibrating piece 3A of this embodiment has a widened portion 64 provided in each of the first recess 50A and the second recess 51A.

[0127] The widened portion 64 provided in the first recess 50A is provided so as to fill in a corner C3 formed by the side surface 35a of the base 35 and the side surface 31Aa of the first vibrating arm 31A. The widened portion 64 provided in the first recess 50A has an inclined surface 64a that is inclined and connected to the side surface 35a of the base 35 and the side surface 31Aa of the first vibrating arm 31A.

[0128] The widening portion 64 provided in the second recess 51A is provided so as to fill in the corner C4 formed by the side surface 35a of the base 35 and the side surface 33Aa of the supporting arm 33A. The widening portion 64 provided in the second recess 51A has an inclined surface 64a that is inclined and connected to the side surface 35a of the base 35 and the side surface 33Aa of the supporting arm 33A.

[0129] The piezoelectric vibrating piece 3A of this embodiment has a single support arm 33A disposed between a pair of the first vibrating arm 31A and the second vibrating arm 32A. The piezoelectric vibrating piece 3A of this embodiment is a so-called center arm type piezoelectric vibrating piece. Therefore, the piezoelectric vibrating piece 3A of this embodiment is a sensor arm type piezoelectric vibrating piece that can prevent the piezoelectric vibrating piece 3A from being damaged by the acute angle structure X1 formed by the etching residue X.

[0130] In this embodiment, a configuration including a widening portion 64 having an inclined surface similar to the widening portion 36 of the first embodiment is adopted. However, for a center arm type piezoelectric vibrating piece, it is also possible to adopt a configuration including a widening portion having a plurality of inclined surfaces as in the second embodiment, a widening portion having a curved surface as in the third embodiment, a widening portion whose curved surface has a variable curvature as in the fourth embodiment, or a widening portion having a symmetrical shape as in the fifth embodiment.

[0131] Seventh embodiment Next, a seventh embodiment of the present invention will be described with reference to Fig. 14. In the description of this embodiment, the description of the same parts as those of the first embodiment will be omitted or simplified.

[0132] FIG. 14 is a schematic diagram showing an oscillator according to this embodiment. As shown in FIG. 14, the oscillator 100 includes a substrate 101, an electronic component 102, an integrated circuit 103, and a piezoelectric vibrator 1. The electronic component 102 is, for example, a capacitor, and is mounted on the substrate 101. The integrated circuit 103 is for the oscillator, and is mounted on the substrate 101. The integrated circuit 103 is electrically connected to the piezoelectric vibrator 1 and the electronic component 102 via wiring (not shown). The piezoelectric vibrator 1 includes the piezoelectric vibrating piece 3 described in the first to fifth embodiments or the piezoelectric vibrating piece 3A described in the sixth embodiment, and is mounted, for example, on the substrate 101 near the integrated circuit 103. The piezoelectric vibrator 1 functions as an oscillator. At least a part of the oscillator 100 may be appropriately molded with a resin (not shown).

[0133] In the oscillator 100, when power is supplied to the piezoelectric vibrator 1, the piezoelectric vibrating piece of the piezoelectric vibrator 1 vibrates. The vibration of the piezoelectric vibrating piece 3 is converted into an electric signal by the piezoelectric characteristics of the piezoelectric vibrating piece 3. This electric signal is output from the piezoelectric vibrator 1 to the integrated circuit 103. The integrated circuit 103 executes various processes on the electric signal output from the piezoelectric vibrator 1 to generate a frequency signal.

[0134] The oscillator 100 can be used, for example, as a single-function oscillator for a clock, a timing control device that controls the operation timing of various devices such as a computer, a device that provides time or a calendar, etc. The integrated circuit 103 is configured according to the functions required for the oscillator 100, and may include a so-called RTC (real-time clock) module.

[0135] The oscillator 100 of this embodiment is highly reliable because it is equipped with the piezoelectric vibrating piece 3 described in the first to fifth embodiments or the piezoelectric vibrating piece 3A described in the sixth embodiment.

[0136] Although the preferred embodiment of the present invention has been described above with reference to the attached drawings, it goes without saying that the present invention is not limited to the above embodiment. The shapes and combinations of the components shown in the above embodiment are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0137] For example, in the above embodiment, the acute angle structure generation suppression functional portion is a widening portion. However, the present invention is not limited to this. For example, it is also possible to adopt a configuration in which the acute angle structure generation suppression functional portion is a groove portion.

[0138] The shape of the widened portion is not limited to the shape shown in the above embodiment, and may be any shape that can reduce the acute angle structure formed by the etching residue X compared to the case where the widened portion is not provided.

[0139] In the above embodiment, the configuration has been described in which the recess is formed by a plurality of portions of the piezoelectric plate 30. However, the present invention is not limited to this. It is also possible to adopt a configuration in which the recess is formed by only a single portion of the piezoelectric plate 30 (for example, a support arm portion).

[0140] In the above embodiment, the widening portion provided in the first recess and the widening portion provided in the second recess have the same shape or a symmetrical shape. However, the present invention is not limited to this. The widening portion provided in the first recess and the widening portion provided in the second recess may have different shapes.

[0141] In the above embodiment, a configuration has been described in which a hammer head type piezoelectric vibrating piece in which the first vibrating arm and the second vibrating arm have a weight portion is used. However, the present invention is not limited to this, and it is also possible to use a straight type piezoelectric vibrating piece in which the first vibrating arm and the second vibrating arm do not have a weight portion. [Explanation of symbols]

[0142] 1: Piezoelectric vibrator, 3: Piezoelectric vibrating piece, 3A: Piezoelectric vibrating piece, 30: Piezoelectric plate, 31: First vibrating arm, 31a: Side, 31A: First vibrating arm, 31Aa: Side, 32: Second vibrating arm, 32a: Side, 32A: Second vibrating arm, 33: First support arm, 33a: Side, 33A: Support arm, 33Aa: Side, 34: Second support arm, 34a: Side, 35: Base, 35a: Side, 36: Widening portion (acute angle structure generation suppression function portion), 36a: Inclined surface, 40: Connection portion, 40a: Side, 41: Longitudinal extension portion, 41a...side surface, 50...first recess, 50A...first recess, 51...second recess, 51A...second recess, 60...widened portion (part having function of suppressing occurrence of acute angle structure), 60a...inclined surface, 61...widened portion (part having function of suppressing occurrence of acute angle structure), 61a...curved surface, 62...widened portion, 62a...curved surface, 63...widened portion (part having function of suppressing occurrence of acute angle structure), 63a...curved surface, 64...widened portion (part having function of suppressing occurrence of acute angle structure), 64a...inclined surface, C1...corner, C2...corner, C3...corner, C4...corner, X...etching residue, X1...acute angle structure

Claims

1. A piezoelectric vibrating piece having a piezoelectric plate made of quartz crystal, the piezoelectric plate having a base, a pair of vibrating arms connected to the base, and a pair of supporting arms connected to the base, In the vibrating arm portion and the supporting arm portion, a recess formed on a plane between the vibrating arm and the supporting arm; a widening portion provided so as to fill a corner portion formed in the recess, In the widening portion, The protruding amount on the supporting arm side is larger than the protruding amount on the vibrating arm side. A piezoelectric vibrating piece characterized by:

2. the widening portion has a curved surface connecting a side surface of the vibrating arm portion and a side surface of the supporting arm portion; The piezoelectric vibrating piece according to claim 1 .

3. The piezoelectric vibrating piece according to claim 1 or 2, a package in which the piezoelectric vibrating piece is hermetically sealed and in which the piezoelectric vibrating piece is mounted via the supporting arm; A piezoelectric vibrator comprising:

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