JP7645104B2 - Piezoelectric vibrating piece and piezoelectric vibrator - Google Patents

Description

The present invention relates to a piezoelectric vibrating piece and a piezoelectric vibrator.

For example, Patent Document 1 discloses a tuning fork-type quartz crystal element having a support arm connected to a base and a pair of vibrating arms connected to the base. The tuning fork-type quartz 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 in an outer corner of the second support arm. Such a tuning fork-type quartz crystal element disclosed in Patent Document 1 can prevent the outer corner of the second support arm from coming into contact with a transport device or the like and being chipped during the manufacturing process.

JP 2018-88576 A

The piezoelectric vibrating piece made of the tuning fork-type quartz element described above has a piezoelectric plate made of quartz. 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 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 quartz is formed by wet etching, etching residues are generated that are not etched 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, etc. to break.

The present invention was made in consideration of the above-mentioned problems, and aims to prevent damage to a piezoelectric vibrating piece that has a piezoelectric plate made of quartz crystal, caused by acute-angle structures formed by etching residue.

The present invention adopts the following configuration as a means for solving the above problems.

A first aspect of the present invention adopts a configuration characterized in that the piezoelectric plate is a piezoelectric vibrating piece having a piezoelectric plate formed 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 have a recess formed on a plane between the vibrating arms and the supporting arms, and a widening portion provided so as to embed a corner formed in the recess, and the widening portion has a greater protrusion amount on the support arm side than on the vibrating arm side.

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.

A second aspect of the present invention employs a configuration in which a curved surface is provided to connect a side surface of the vibrating arm portion and a side surface of the supporting arm portion .

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 etching residue at the boundary between the widening portion and the inner wall surface of the recess.

A third aspect of the present invention is a piezoelectric vibrator comprising a piezoelectric vibration piece of the first or second aspect described above, and a package that hermetically seals the piezoelectric vibration piece and in which the piezoelectric vibration piece is mounted via the support arm portion.

The present invention makes it possible to provide a piezoelectric vibrator that can prevent damage to the piezoelectric vibrating piece caused by sharp-angled structures left behind by etching.

According to the present invention, in a piezoelectric vibrating piece having a piezoelectric plate formed from quartz crystal, it is possible to prevent the piezoelectric vibrating piece from being damaged by the acute angle structure formed by etching residue.

1 is an external perspective view of a piezoelectric vibrator according to a first embodiment of the present invention. FIG. 4 is a plan view of the piezoelectric vibrator with the sealing plate removed. 3 is a cross-sectional view corresponding to line II in FIG. 2. 1 is an exploded perspective view of a piezoelectric vibrator according to a first embodiment of the present invention. 1 is a plan view of a piezoelectric vibrating piece according to a first embodiment of the present invention; 6 is a cross-sectional view corresponding to line II-II in FIG. 5. 4A is a schematic enlarged view including a first recess of a piezoelectric plate according to a first embodiment of the present invention, and FIG. 4B is a schematic enlarged view of the first recess when no widened portion is provided. 4 is a flowchart showing a method for manufacturing the piezoelectric vibrating piece according to the first embodiment. (a) is a schematic enlarged view of an widening portion provided in a first recess in accordance with a second embodiment of the present invention, and (b) is a schematic enlarged view of an widening portion provided in a second recess in accordance with a second embodiment of the present invention. (a) is a schematic enlarged view of an widening 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 widening portion provided in a second recess in accordance with a third embodiment of the present invention. (a) is a schematic enlarged view of an widening portion provided in a first recess in accordance with a fourth embodiment of the present invention, and (b) is a schematic enlarged view of an widening portion provided in a second recess in accordance with the fourth embodiment of the present invention. (a) is a schematic enlarged view of an widening portion provided in a first recess in accordance with a fifth embodiment of the present invention, and (b) is a schematic enlarged view of an widening portion provided in a second recess in accordance with a fifth embodiment of the present invention. FIG. 13 is a plan view of a piezoelectric vibrating reed according to a sixth embodiment of the present invention. FIG. 13 is a schematic diagram showing an oscillator according to a seventh embodiment of the present invention.

Below, an embodiment of a piezoelectric vibrating piece and a piezoelectric vibrator according to the present invention will be described with reference to the drawings.

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 the 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.

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

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 electrode 2d and external electrode 2e) are formed on the lower surface of the first base substrate 2a with a gap in the longitudinal direction L. The external electrodes 2d and 2e are formed 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 second base substrate 2b is a ceramic substrate having the same shape as the first base substrate 2a in plan view, and is bonded integrally by sintering or the like while being stacked on the first base substrate 2a. Note that examples of ceramic materials that can be used for the first base substrate 2a and the second base substrate 2b include alumina HTCC (High Temperature Co-Fired Ceramic) and glass ceramic LTCC (Low Temperature Co-Fired Ceramic).

As shown in Figures 2 to 4, the second base substrate 2b has a through-hole 2f that 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) that protrude inward in the width direction W are formed separately in portions located on both sides in the width direction W. Mounting portion 2g and mounting portion 2h are located in the center of the second base substrate 2b in the longitudinal direction L.

On the mounting portion 2g and the mounting portion 2h, a pair of electrode pads (electrode pad 2i and electrode pad 2j) that are connection electrodes with the piezoelectric vibrating piece 3 are formed. Like the external electrode 2d and external electrode 2e described above, the electrode pad 2i and electrode pad 2j are composed 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 pad 2i and electrode pad 2j and the external electrode 2d and external electrode 2e are each electrically connected to each other via a through-wire (not shown) that penetrates the first base substrate 2a and the second base substrate 2b in the thickness direction T.

At the four corners of the first base substrate 2a and the second base substrate 2b, cutout portions 2k having a 1/4 circular arc shape in plan view are 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 produced, for example, by stacking and bonding two wafer-shaped ceramic substrates, forming a matrix of through holes penetrating both ceramic substrates, and cutting both ceramic substrates into a lattice shape using each through hole as a reference. At this time, the through holes are divided into four to form the above-mentioned cutout portions 2k.

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.

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, if alumina with a thermal expansion coefficient of 6.8×10-6/°C is used for 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 for the seal ring 2c.

The sealing plate 5 is made of a conductive substrate and is joined onto the seal ring 2c to hermetically 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.

The piezoelectric vibrating piece 3 is housed in a cavity C of the hermetically sealed package 2. In this embodiment, the piezoelectric vibrating piece 3 includes a piezoelectric plate 30 formed of quartz. The piezoelectric plate 30 has a pair of vibrating arms (first vibrating arm 31 and second vibrating arm 32) and a pair of supporting arms (first supporting arm 33 and 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 on the mounting portion 2g and the second supporting arm 34 being supported on the mounting portion 2h by 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 first vibrating arm 31 and second vibrating arm 32 when a predetermined voltage is applied.

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 at a predetermined resonant frequency, for example, in a direction approaching or separating from each other (width direction W), 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.

(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.

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 portion 36 (acute angle structure generation suppression function portion). 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.

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 and moving away from each other (width direction W). The first vibrating arm 31 and the second vibrating arm 32 have a main body portion 37 extending from the base ends of the first vibrating arm 31 and the second vibrating arm 32 toward the tips, and a weight portion 38 located at the tips of the first vibrating arm 31 and the second vibrating arm 32.

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

The weights 38 each extend in the longitudinal direction L from the tip of the main body 37. The weights 38 are rectangular in plan view and are wider in the width direction W than the main body 37. This increases 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 allows the length of the first vibrating arm 31 and the second vibrating arm 32 to be shortened compared to a piezoelectric vibrating piece 3 that does not have a weight 38.

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.

As shown in FIG. 5, the piezoelectric plate 30 has a plurality of recesses when viewed from the thickness direction T. For example, in this embodiment, a first recess 50 is provided, which is formed by the first support arm 33, the base 35, and the first vibrating arm 31. In addition, a second recess 51 is provided, which is formed by the second support arm 34, the base 35, and the second vibrating arm 32.

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

The widening 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.

If the first recess 50 does not have the widening portion 36, the corner C1 formed by connecting the side 41a of the longitudinal extension portion 41 of the first support arm portion 33 and the side 40a of the connection 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 bury the corner C1.

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. As shown in FIG. 5, 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.

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 35 and the side surface 40a of the connection portion 40 of the second support arm 34 is exposed. The widening portion 36 provided in the second recess 51 is provided in the second recess 51 so as to bury the corner C2.

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 34. As shown in FIG. 5, 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 34.

Figure 6 is a cross-sectional view corresponding to line II-II in Figure 5. As shown in Figure 6, the dimension of the base 35 in the thickness direction T (thickness dimension 35D) is the same as the dimension of the first support arm 33 in the thickness direction T (thickness dimension 33D) and the dimension of the second support arm 34 in the thickness direction T (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 flush. 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 flush.

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. In other words, 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. In other words, 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. In other words, 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.

Here, the relationship between the shape of the piezoelectric plate 30 and the crystal axis of the quartz, which is the material forming the piezoelectric plate 30, will be described. For example, the electrical 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 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. At this time, in this embodiment, the X axis coincides with the width direction W shown in FIG. 5, etc., the Y' axis coincides with the longitudinal direction L shown in FIG. 5, etc., and the Z' axis coincides with the thickness direction T shown in FIG. 5, etc. In other words, 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 and the Y'-axis.

That is, in a coordinate system in which 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, the Z axis is rotated around the X axis within a range of -5° to +10° to create a new axis called the Z' axis, and the Y axis is rotated around the X axis as the rotation axis by the same angle as the Z axis in a plane including the Z axis and the Y axis to create a new axis called the Y' axis. In this embodiment, in a plan 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 provided extending 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.

Figure 7(a) is a schematic enlarged view including the first recess 50 of the piezoelectric plate 30 of this embodiment. Figure 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 using wet etching as described below, etching residue X is generated on the side of the piezoelectric plate 30, as shown in Figures 7(a) and 7(b). This etching residue X is a portion that protrudes from the outer shape of the mask used in wet etching when viewed from the Z' axis direction, and is an etching residue portion that occurs 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.

For example, as shown in FIG. 7B, when the widening portion 36 is not provided in the first recess 50, a large amount of etching residue X occurs 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 near 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 be the starting point of a crack that occurs in the piezoelectric plate 30. Note that the etching residue X is omitted in the drawings other than FIG. 7.

On the other hand, as shown in FIG. 7(a), in the piezoelectric vibrating piece 3 of this embodiment, a widening 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.

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.

In addition, if the widening 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 on the side surface 35a on the second support arm 34 side of the base 35. As a result, an acute angle structure (not shown) similar to the acute angle structure X1 shown in FIG. 7(a) is formed near the corner C2. In contrast, in the piezoelectric vibrating piece 3 of this embodiment, the widening 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 that may cause damage to the piezoelectric plate 30, i.e., the piezoelectric vibrating piece 3.

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 in a direction along a plane including the X-axis and Y'-axis, starting from the corner C2. 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.

The electrode film is, for example, a laminated film of chromium (Cr) and gold (Au), which is formed by depositing a chromium film, which has good adhesion to quartz crystal, as a base, and then laminating a thin film of gold on the chromium film. 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.

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.

(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.

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

Here, in the manufacturing method of the piezoelectric vibrating piece 3 of this embodiment, the external 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 external shape of the widened portion 36 is also formed at the same time. Specifically, the shape of the mask is made to cover the area where the widened portion 36 is to be formed. By performing wet etching using such a mask, the external 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 external shape of the widened portion 36 is also formed at the same time.

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 using photolithography technology. Next, half-etching is performed on the quartz wafer using wet etching to the extent that the grooves 39 do not penetrate the quartz wafer. This forms a piezoelectric plate 30 with grooves 39 on the wafer.

Then, the electrode film forming process S20 is performed. In the electrode film forming process S20, an electrode film is arranged on the front and back surfaces of the piezoelectric plate 30. The electrode film forming process S20 includes an electrode film forming process for forming an electrode film, and a patterning process for patterning the electrode film to form excitation electrodes, etc.

In the electrode film formation process, an electrode film is formed on the front and back surfaces and end faces of the quartz crystal wafer by sputtering, vapor 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 with 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, mounting electrodes, and connection wiring are formed on the piezoelectric plate 30.

Through this external shape forming process S10 and electrode film forming process S20, multiple piezoelectric vibrating pieces 3 are formed on a single quartz crystal wafer.

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 against 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.

The piezoelectric vibrating piece 3 of this embodiment as described above includes a piezoelectric plate 30 formed of quartz, and the piezoelectric plate 30 includes a base 35 and a pair of first vibrating arm 31 and second vibrating arm 32 connected to the base 35. The piezoelectric vibrating piece 3 of this 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 formed of quartz. The piezoelectric vibrating piece 3 of this 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. Furthermore, the piezoelectric vibrating piece 3 has a widening 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.

The shape of the etching residue X in the piezoelectric plate 30 made of quartz is determined depending on the direction of the crystal axis. In other words, when piezoelectric plates 30 with the same crystal axis direction are formed, etching residue X of the same shape is generated. For this reason, 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.

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

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 support arm 33, and the second support arm 34. In addition, in the piezoelectric vibrating piece 3 of this embodiment, the acute angle structure occurrence suppression functional portion is the widening portion 36 provided by embedding the corners C1 and C2.

According to the piezoelectric vibrating piece 3 of this embodiment, it is possible to improve the strength of the piezoelectric vibrating piece 3, for example, compared to a case where the acute angle structure generation suppression functional portion is a groove portion or the like. 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.

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 35. Therefore, in the manufacturing process, the widened portion 36 can be formed at the same time as the base 35 is formed by etching, and there is no need to perform post-processing on the widened portion 36 after the base 35 is formed. This makes it possible to easily form the widened portion 36.

In addition, in the piezoelectric vibrating piece 3 of this embodiment, the widening portion 36 has an inclined surface 36a that is inclined with respect to the first side surface and the second side surface that form the corner. For example, the inclined surface 36a of the widening portion 36 provided in the first recess 50 is inclined and connected to the side surface 41a (first side surface) of the longitudinal extension portion 41 of the first support arm portion 33 that forms the corner portion C1 and the side surface 40a (second side surface) of the connection portion 40 of the first support arm portion 33. In addition, the inclined surface 36a of the widening portion 36 provided in the second recess 51 is inclined and connected to the side surface 35a (first side surface) of the base portion 35 that forms the corner portion C2 and the side surface 40a (second side surface) of the connection portion 40 of the second support arm portion 34.

According to the piezoelectric vibrating piece 3 of this embodiment, the connection angle between the side 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 between the widening portion 36 and the inner wall surfaces of the first recess 50 and the second recess 51.

The piezoelectric vibrating piece 3 of this embodiment also has two first support arms 33 and two second support arms 34, each of which is 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 piece 3 of this embodiment is a so-called side arm type piezoelectric vibrating piece. Therefore, the piezoelectric vibrating piece 3 of this embodiment is a side arm type piezoelectric vibrating piece that can prevent the piezoelectric vibrating piece 3 from being damaged by the acute angle structure X1 formed by the etching residue X.

In addition, in the piezoelectric vibrating piece 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, the new axis obtained by rotating the Z axis around the X axis within a range of -5° to +10° is the Z' axis, and the 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 around the X axis is the Y' axis. In this orthogonal 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, the second vibrating arm 32, 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.

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 extend from the base 35 along a plane including the X-axis-Y'-axis as described above, an acute angle structure X1 is likely to occur due to the etching residue X in the first recess 50 and the second recess 51. According to the piezoelectric vibrating piece 3 of this embodiment, even though an acute angle structure X1 is likely to occur due to the etching residue X in the first recess 50 and the second recess 51, by providing the widened portion 36, it is possible to effectively prevent the piezoelectric vibrating piece 3 from being damaged.

The piezoelectric vibrator 1 of this embodiment also 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 support arm 33 and a second support 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 is highly reliable.

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 of the first embodiment will be omitted or simplified.

In the piezoelectric vibrating piece 3 of the first embodiment described above, the widening portion 36 has a single inclined surface 36a with a constant inclination angle. In contrast, in this embodiment, the widening portion 60 has multiple (two in this embodiment) inclined surfaces 60a with different angles relative to the side surface that forms the corner.

Figure 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 so 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 relative 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.

The inclination angle of the inclined surface 60a located on the side 41a of the longitudinal extension 41 of the first support arm 33 with respect to the side 41a is smaller than the inclination angle of the inclined surface 60a located on the side 40a of the connection portion 40 of the first support arm 33 with respect to the side 41a. In other words, of 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 41a of the longitudinal extension 41 of the first support arm 33 with respect to the side 41a is the smallest compared to the inclination angles of the other inclined surfaces 60a with respect to the side 41a.

The inclination angle of the inclined surface 60a located on the side 40a of the connection portion 40 of the first support arm portion 33 with respect to the side 40a is smaller than the inclination angle of the inclined surface 60a located on the side 41a of the longitudinal extension portion 41 of the first support arm portion 33 with respect to the side 40a. In other words, of 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 40a of the connection portion 40 of the first support arm portion 33 with respect to the side 40a is the smallest relative to the inclination angles of the other inclined surfaces with respect to the side 40a.

For example, the angle of the normal of 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 of 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 of 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.

Figure 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 relative to the side surface 35a of the base 35 (side surface 40a of the connection portion 40 of the second support arm 34) are different.

The inclination angle of the inclined surface 60a located on the side 35a of the base 35 relative to the side 35a is the smallest relative to the inclination angle of the inclined surface 60a located on the side 40a of the connection portion 40 of the second support arm 34 relative to the side 35a. In other words, of 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 35a of the base 35 relative to the side 35a is the smallest relative to the inclination angles of the other inclined surfaces 60a relative to the side 35a.

The inclination angle of the inclined surface 60a located on the side 40a of the connection portion 40 of the second support arm portion 34 relative to the side 40a is the smallest relative to the inclination angle of the inclined surface 60a located on the side 35a of the base portion 35 relative to the side 40a. In other words, of 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 40a of the connection portion 40 of the second support arm portion 34 relative to the side 40a is the smallest relative to the inclination angles of the other inclined surfaces relative to the side 40a.

For example, the angle of the normal of 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 of the inclined surface 60a located on the side 40a of the connection part 40 of the second support arm 34 with respect to the X-axis is set to twice the angle of the normal of the inclined surface 60a located on the side 35a of the base 35 with respect to the X-axis.

According to the piezoelectric vibrating piece 3 of this embodiment, the connection angle between the side 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, making it possible to better prevent the occurrence of acute angle structures X1 due to etching residue X at the boundaries between the widening portion 60 and the inner wall surfaces of the first recess 50 and the second recess 51.

In this 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.

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.

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

Figure 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 so that the 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.

Figure 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 so that the 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.

According to the piezoelectric vibrating piece 3 of this embodiment, the connection angle between the side 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 between the widening portion 60 and the inner wall surfaces of the first recess 50 and the second recess 51.

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 of the first embodiment will be omitted or simplified.

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

Figure 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, the center of which 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 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.

Figure 11 (b) is a schematic enlarged view of the widening portion 62 provided in the second recess 51. As shown in this figure, the widening portion 62 provided in the second recess 51 is provided so that the 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 34.

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 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.

According to the piezoelectric vibrating piece 3 of this embodiment, the connection angle between the side 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 better prevent the occurrence of an acute angle structure X1 due to etching residue X at the boundary between the widening portion 62 and the inner wall surfaces of the first recess 50 and the second recess 51.

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.

In the piezoelectric vibrating piece 3 of the first embodiment described above, the widening portion 36 provided in the first recess 50 and the widening portion 36 provided in the second recess 51 have shapes that are asymmetric with respect to the central axis O when viewed from the thickness direction T. In contrast, in this embodiment, the widening portion 63 provided in the first recess 50 and the widening portion 63 provided in the second recess 51 have shapes that are symmetric with respect to the central axis O when viewed from the thickness direction T.

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

The widening portion 63 provided in the first recess 50 protrudes from the base 35 of the portion on the first vibrating arm 31 side less than the amount of protrusion from the base 35 of the portion on the first support arm 33 side by the distance Da shown in FIG. 12(a). In other words, in this embodiment, the contact area between the first vibrating arm 31 and the widening portion 63 is smaller than when the amount of protrusion from the base 35 of the portion on the first vibrating arm 31 side is the same as the amount of protrusion from the base 35 of the portion on the first support arm 33 side.

Figure 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 support arm 34 and the side surface 32a of the second vibrating arm 32.

The widening portion 63 provided in the second recess 51 protrudes from the base 35 of the portion on the second vibrating arm 32 side less than the amount of protrusion from the base 35 of the portion on the second support arm 34 side by the distance Da shown in FIG. 12(b). In other words, in this embodiment, the contact area between the second vibrating arm 32 and the widening portion 63 is smaller than when the amount of protrusion from the base 35 of the portion on the second vibrating arm 32 side is the same as the amount of protrusion from the base 35 of the portion on the second support arm 34 side.

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.

In addition, according to the piezoelectric vibrating piece 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 between the first support arm 33 and the widened portion 63. In addition, 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 between the second support arm 34 and 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 piece 3.

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 of the first embodiment will be omitted or simplified.

The piezoelectric vibrating piece 3 in the first embodiment described above was a so-called side arm type piezoelectric vibrating piece. In contrast, the piezoelectric vibrating piece 3A in this embodiment is a so-called center arm type piezoelectric vibrating piece.

Figure 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 support arm 33A disposed between a pair of first vibrating arm 31A and second vibrating arm 32A. As shown in Figure 13, the piezoelectric vibrating reed 3A of this embodiment has a first recess 50A formed by the first vibrating arm 31A, the support arm 33A, and a base 35.

The piezoelectric vibrating piece 3A of this embodiment also has a second recess 51A formed by the second vibrating arm portion 32A, the support arm portion 33A, and the base portion 35. The piezoelectric vibrating piece 3A of this embodiment also has a widening portion 64 provided in each of the first recess 50A and the second recess 51A.

The widening portion 64 provided in the first recess 50A is provided to fill the corner C3 formed by the side surface 35a of the base 35 and the side surface 31Aa of the first vibrating arm 31A. The widening 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.

The widening portion 64 provided in the second recess 51A is provided to fill the corner C4 formed by the side surface 35a of the base 35 and the side surface 33Aa of the support 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 support arm 33A.

The piezoelectric vibrating piece 3A of this embodiment has a single support arm 33A disposed between a pair of first vibrating arm 31A and 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.

In this embodiment, a configuration is adopted that includes a widening portion 64 having an inclined surface similar to the widening portion 36 of the first embodiment. However, for a center arm type piezoelectric vibrating piece, it is also possible to adopt a configuration that includes a widening portion having multiple 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.

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.

Figure 14 is a schematic diagram showing an oscillator according to this embodiment. As shown in Figure 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 molded with a resin (not shown) as appropriate.

When power is supplied to the piezoelectric vibrator 1, the oscillator 100 vibrates the piezoelectric vibrating piece of the piezoelectric vibrator 1. The vibration of the piezoelectric vibrating piece 3 is converted into an electrical signal by the piezoelectric characteristics of the piezoelectric vibrating piece 3. This electrical signal is output from the piezoelectric vibrator 1 to the integrated circuit 103. The integrated circuit 103 generates a frequency signal by performing various processes on the electrical signal output from the piezoelectric vibrator 1.

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, or a device that provides time or a calendar. The integrated circuit 103 is configured according to the functions required of the oscillator 100, and may include a so-called RTC (real-time clock) module.

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

The above describes a preferred embodiment of the present invention with reference to the attached drawings, but 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.

For example, in the above embodiment, a configuration in which the acute angle structure generation suppression functional part is a widening part has been described. 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 part is a groove part.

The shape of the widening portion is not limited to the shape shown in the above embodiment. The shape of the widening portion may be any shape that can reduce the acute angle structure formed by the etching residue X compared to the case where no widening portion is provided.

In the above embodiment, a configuration in which the recess is formed by multiple parts of the piezoelectric plate 30 has been described. 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 part of the piezoelectric plate 30 (e.g., the support arm portion).

In the above embodiment, the configuration has been described in which 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.

In addition, in the above embodiment, a configuration has been described in which a hammer head type piezoelectric vibrating piece is used in which the first vibrating arm and the second vibrating arm have a weight portion. 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.

1...piezoelectric vibrator, 3...piezoelectric vibrating piece, 3A...piezoelectric vibrating piece, 30...piezoelectric plate, 31...first vibrating arm, 31a...side surface, 31A...first vibrating arm, 31Aa...side surface, 32...second vibrating arm, 32a...side surface, 32A...second vibrating arm, 33...first support arm, 33a...side surface, 33A...support arm, 33Aa...side surface, 34...second support arm, 34a...side surface, 35...base, 35a...side surface, 36...widening portion (acute angle structure generation suppression function portion), 36a...inclined surface, 40...connection portion, 40a...side surface, 41...longitudinal extension part, 41a...side surface, 50...first recess, 50A...first recess, 51...second recess, 51A...second recess, 60...widening part (part with function to suppress occurrence of acute angle structure), 60a...inclined surface, 61...widening part (part with function to suppress occurrence of acute angle structure), 61a...curved surface, 62...widening part, 62a...curved surface, 63...widening part (part with function to suppress occurrence of acute angle structure), 63a...curved surface, 64...widening part (part with function to suppress occurrence of acute angle structure), 64a...inclined surface, C1...corner, C2...corner, C3...corner, C4...corner, X...etching residue, X1...acute angle structure

Claims (3)

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: 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 . 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:

Images