JP6587389B2 - Piezoelectric vibrating piece and piezoelectric vibrator - Google Patents

Description

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

  For example, in a mobile phone or a portable information terminal device, a piezoelectric vibrator using a crystal or the like is used as a device used for a time source, a timing source such as a control signal, a reference signal source, or the like. As this type of piezoelectric vibrator, a piezoelectric vibrator in which a piezoelectric vibrating piece is hermetically sealed in a package in which a cavity is formed is known.

  As a piezoelectric vibrating piece, in order to reduce crystal impedance (hereinafter referred to as “CI value”), a pair of vibrating arms arranged side by side is known to have a groove. For example, a piezoelectric vibrating piece described in Patent Document 1 includes a vibrating arm having a base, at least one arm extending from the base, and a weight formed at the tip of the arm and wider than the arm (see Claims). The vibrating arm is formed along the direction in which the vibrating arm extends, and the cross-sectional shape of the vibrating arm cut in the direction in which the pair of vibrating arms is arranged is an H-shape. It has the groove part which becomes.

JP 2011-182024 A

  However, in the piezoelectric vibrating piece described in Patent Document 1, the groove arm portion reduces the cross-sectional area of the vibrating arm portion, so that the strength of the vibrating arm portion decreases. Therefore, the conventional piezoelectric vibrating piece has room for improvement in terms of improving the strength of the vibrating arm portion while reducing the CI value by providing the groove portion.

  Accordingly, the present invention provides a piezoelectric vibrating piece and a piezoelectric vibrator capable of improving the strength of a vibrating arm portion while reducing the CI value.

The piezoelectric vibrating piece of the present invention is formed on a pair of vibrating arm portions arranged and extending side by side, a base portion connecting base ends of the pair of vibrating arm portions, and the pair of vibrating arm portions, A groove portion that is recessed in the thickness direction of the vibrating arm portion, extends along the longitudinal direction of the vibrating arm portion, and a plurality of protrusion portions that are formed in the bottom portion of the groove portion and project in the thickness direction of the vibrating arm portion; It is characterized by providing.
According to the present invention, by providing the protrusion in the groove, the opening area of the etching mask at the time of forming the groove is reduced. Therefore, the etching rate around the protrusion is reduced at the time of forming the groove, and the depth of the groove around the protrusion is reduced. The depth can be reduced. For this reason, the cross-sectional area of the vibrating arm portion can be increased at the position where the protrusion is formed. Therefore, the strength of the vibrating arm can be improved while reducing the CI value by providing the groove.

In the above-described piezoelectric vibrating piece, it is preferable that the plurality of projecting portions are arranged side by side along the longitudinal direction of the vibrating arm portion.
According to the present invention, by arranging the plurality of protrusions side by side along the longitudinal direction of the vibrating arm portion, the arrangement direction of the plurality of protrusion portions and the longitudinal direction of the groove portion coincide with each other. The strength of the portion where the groove is formed can be improved uniformly.

In the above-described piezoelectric vibrating piece, it is preferable that the plurality of projecting portions are arranged so that an interval between the adjacent projecting portions is narrowed from a tip end to a base end of the groove portion.
The stress acting on the bending vibration arm portion increases as it goes from the distal end to the proximal end. According to the present invention, since the plurality of protrusions are arranged so as to become denser from the tip of the groove portion toward the base end, the strength of the vibrating arm portion can be increased as it goes from the tip to the base end. it can. Therefore, the strength of the vibrating arm can be further improved.

In the piezoelectric vibrating piece, the groove includes a pair of side wall surfaces formed on both sides in the width direction of the vibrating arm unit, and one of the pair of side wall surfaces is the other side wall surface. Than the central part of the groove part in the width direction of the vibrating arm part, and the plurality of protrusions are formed on the other side wall surface side. Is desirable.
Since one side wall surface has a larger inclination angle with respect to the thickness direction of the vibrating arm portion than the other side wall surface, the thickness of the side wall located on both sides in the width direction of the vibrating arm portion is larger than that of the side wall having one side wall surface. However, the side wall having the other side wall surface is thinner. For this reason, the cross-sectional area of the vibrating arm portion differs on both sides across the widthwise central portion, and the strength of the vibrating arm portion also differs on both sides across the widthwise central portion. According to the present invention, since the protruding portion is formed on the other side wall surface side than the central portion of the groove portion, the cross-sectional area of the vibrating arm portion can be made equal on both sides across the central portion in the width direction. . Therefore, the strength of the vibrating arm portion can be made equal on both sides of the central portion in the width direction, and the strength of the vibrating arm portion can be further improved.

In the above-described piezoelectric vibrating piece, it is preferable that the plurality of projecting portions are formed lower than a main surface of the vibrating arm portion.
According to the present invention, since the protruding portion is formed lower than the main surface of the vibrating arm portion, unevenness in the groove portion is reduced. This makes it easier for the photoresist to enter the bottom of the groove when patterning the electrode film provided on the surface of the vibrating arm. Therefore, the manufacturing efficiency of the piezoelectric vibrating piece can be improved.

A piezoelectric vibrator according to the present invention includes the above-described piezoelectric vibrating piece.
According to the present invention, since the above-described piezoelectric vibrating piece is provided, a piezoelectric vibrator in which the strength of the vibrating arm portion is improved while the CI value is reduced can be obtained.

  According to the present invention, by providing the protrusion in the groove, the opening area of the etching mask at the time of forming the groove is reduced. Therefore, the etching rate around the protrusion is reduced at the time of forming the groove, and the depth of the groove around the protrusion is reduced. The depth can be reduced. For this reason, the cross-sectional area of the vibrating arm portion can be increased at the position where the protrusion is formed. Therefore, the strength of the vibrating arm can be improved while reducing the CI value by providing the groove.

It is an external perspective view of a piezoelectric vibrator. It is an internal block diagram of a piezoelectric vibrator. It is sectional drawing in the III-III line of FIG. It is a disassembled perspective view of a piezoelectric vibrator. It is a top view of a piezoelectric vibrating piece. It is sectional drawing in the VI-VI line of FIG. It is sectional drawing in the VII-VII line of FIG. FIG. 7 is an explanatory diagram of a piezoelectric vibrating piece according to a first modification, and is a cross-sectional view of a portion corresponding to the line VII-VII in FIG. 5. It is explanatory drawing of the piezoelectric vibrating piece of a 2nd modification, and is sectional drawing in the part corresponded in the VII-VII line of FIG. It is a top view of the piezoelectric vibrating piece of the 3rd modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Piezoelectric vibrator)
FIG. 1 is an external perspective view of a piezoelectric vibrator. FIG. 2 is an internal configuration diagram of the piezoelectric vibrator. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is an exploded perspective view of the piezoelectric vibrator.

As shown in FIGS. 1 to 4, the piezoelectric vibrator 1 according to the present embodiment includes a package 2 having a cavity C hermetically sealed therein, and a piezoelectric vibrating piece 3 accommodated in the cavity C. It is a ceramic package type surface-mount type resonator.
The piezoelectric vibrator 1 is formed in a substantially rectangular parallelepiped shape. In the present embodiment, the longitudinal direction of the piezoelectric vibrator 1 is referred to as a longitudinal direction L and the short side direction is referred to as a width direction W in plan view. A direction orthogonal to the direction L and the width direction W is referred to as a thickness direction T.

The package 2 includes a package body 5 and a sealing plate 6 that is bonded to the package body 5 and that forms a cavity C between the package body 5 and the package body 5.
The package main body 5 includes a first base substrate 10 and a second base substrate 11 which are joined in a state of being overlapped with each other, and a seal ring 12 which is joined on the second base substrate 11.

  At the four corners of the first base substrate 10 and the second base substrate 11, cutout portions 15 having a ¼ arc shape in plan view are formed over the entire thickness direction of both the base substrates 10 and 11. The first base substrate 10 and the second base substrate 11 are formed, for example, by stacking and joining two wafer-like ceramic substrates, and then forming a plurality of through-holes penetrating both ceramic substrates in a matrix form. It is produced by cutting both ceramic substrates into a lattice shape with reference to the holes. At this time, the through hole is divided into four parts, thereby forming the cutout part 15.

  Although the first base substrate 10 and the second base substrate 11 are made of ceramics, specific ceramic materials include, for example, HTCC (High Temperature Co-Fired Ceramic) made of alumina, or LTCC (made of glass ceramics). Low Temperature Co-Fired Ceramic) and the like.

The upper surface of the first base substrate 10 corresponds to the bottom surface of the cavity C.
The second base substrate 11 is superimposed on the first base substrate 10 and is bonded to the first base substrate 10 by sintering or the like. That is, the second base substrate 11 is integrated with the first base substrate 10.

  The second base substrate 11 has a penetrating part 11a. The through portion 11a is formed in a rectangular shape in plan view with rounded corners. The inner side surface of the penetrating portion 11a constitutes a part of the side wall of the cavity C. Mounting portions 14A and 14B projecting inward are provided on inner side surfaces of both sides in the width direction W of the penetrating portion 11a. The mounting portions 14A and 14B are formed at substantially the center in the longitudinal direction L of the penetrating portion 11a.

  The seal ring 12 is a conductive frame-like member that is slightly smaller than the outer shape of the first base substrate 10 and the second base substrate 11, and is bonded to the upper surface of the second base substrate 11. Specifically, the seal ring 12 is bonded onto the second base substrate 11 by baking with a brazing material such as silver brazing or a solder material, or is formed on the second base substrate 11 (for example, electrolytic plating or electroless). In addition to plating, bonding is performed by welding or the like to a metal bonding layer formed by vapor deposition or sputtering.

Examples of the material of the seal ring 12 include a nickel-based alloy, and specifically, it may be selected from Kovar, Elinvar, Invar, 42-alloy, and the like. In particular, as the material of the seal ring 12, it is preferable to select a material having a thermal expansion coefficient close to that of the first base substrate 10 and the second base substrate 11 made of ceramics. For example, when alumina having a thermal expansion coefficient of 6.8 × 10 ⁻⁶ / ° C. is used as the first base substrate 10 and the second base substrate 11, the seal ring 12 has a thermal expansion coefficient of 5.2 × 10 ⁻ It is preferable to use ⁶ / ° C. Kovar or a 42-alloy having a thermal expansion coefficient of 4.5 to 6.5 × 10 ⁻⁶ / ° C.

  The sealing plate 6 is a conductive substrate stacked on the seal ring 12, and is hermetically bonded to the package body 5 by bonding to the seal ring 12. A space defined by the sealing plate 6, the seal ring 12, the penetrating portion 11 a of the second base substrate 11, and the upper surface of the first base substrate 10 functions as a hermetically sealed cavity C.

  Examples of the welding method of the sealing plate 6 include seam welding by bringing a roller electrode into contact, laser welding, ultrasonic welding, and the like. Moreover, in order to make the welding of the sealing plate 6 and the seal ring 12 more reliable, a bonding layer such as nickel or gold that is familiar to each other is provided at least on the lower surface of the sealing plate 6 and the upper surface of the seal ring 12. It is preferable to form.

  A pair of electrode pads 20 </ b> A and 20 </ b> B, which are connection electrodes to the piezoelectric vibrating reed 3, are formed on the upper surfaces of the mounting portions 14 </ b> A and 14 </ b> B of the second base substrate 11. A pair of external electrodes 21 </ b> A and 21 </ b> B are formed on the lower surface of the first base substrate 10 at intervals in the longitudinal direction L. The electrode pads 20A and 20B and the external electrodes 21A and 21B are, for example, a single-layer film made of a single metal formed by vapor deposition or sputtering, or a laminated film in which different metals are stacked, and are mutually connected via a wiring (not shown). Each is conducting.

(Piezoelectric vibrating piece)
FIG. 5 is a plan view of the piezoelectric vibrating piece.
As shown in FIG. 5, the piezoelectric vibrating piece 3 is a vibrating piece made of a piezoelectric material such as quartz, lithium tantalate, or lithium niobate, and vibrates when a predetermined voltage is applied. In the following description, quartz will be described as an example of the piezoelectric material. In addition, the longitudinal direction L, the width direction W, and the thickness direction T of the piezoelectric vibrator 1 coincide with the longitudinal direction, the width direction, and the thickness direction of the piezoelectric vibrating piece 3. Therefore, in the following description, the same reference numerals as those of the longitudinal direction L, the width direction W, and the thickness direction T of the piezoelectric vibrator 1 are attached to the longitudinal direction, the width direction, and the thickness direction of the piezoelectric vibrating piece 3. To explain.

The piezoelectric vibrating piece 3 includes a pair of vibrating arm portions (first vibrating arm portion 31 and second vibrating arm portion 32), a base portion 35, and a pair of supporting arm portions (first supporting arm portion 33 and second supporting arm portion). 34).
The vibrating arm portions 31 and 32 extend in the longitudinal direction L and are arranged side by side in the width direction W. The vibrating arm portions 31 and 32 vibrate with the base ends 31b and 32b as fixed ends and the tips 31a and 32a as free ends. Each of the vibrating arm portions 31 and 32 is, for example, a so-called hammer head type in which the widths of the distal ends 31a and 32a are larger than those of the proximal ends 31b and 32b. The weight of 32a and the moment of inertia during vibration are increased. Accordingly, the vibrating arm portions 31 and 32 can easily vibrate, the length of the vibrating arm portions 31 and 32 can be shortened, and the size can be reduced. In this embodiment, the hammer head type vibrating arm portions 31 and 32 will be described as an example. However, the vibrating arm portions 31 and 32 are not limited to the hammer head type.

6 is a cross-sectional view taken along line VI-VI in FIG.
As shown in FIG. 6, groove portions 37 are formed in the respective vibrating arm portions 31 and 32. The groove portion 37 is recessed in the thickness direction T and extends along the longitudinal direction L on both main surfaces 31c and 32c of the vibrating arm portions 31 and 32 (see FIG. 5). Since the four groove portions 37 formed on both main surfaces 31c and 32c of the respective vibrating arm portions 31 and 32 are formed in the same manner, in the following description, one of the first vibrating arm portions 31 will be described. The groove part 37 formed on the main surface 31c will be described.

  The groove portion 37 is defined by a pair of side wall surfaces 38 located on both sides in the width direction W when viewed from the longitudinal direction L, and a bottom portion 39. The pair of side wall surfaces 38 is located on one side in the width direction W, and is located on the other side in the width direction W and the first side wall surface 38a inclined with respect to the thickness direction T by the crystal plane of the quartz crystal. And a second side wall surface 38b formed along T. The bottom 39 is V-shaped when viewed from the longitudinal direction L by a first bottom surface 39a connected to the first side wall surface 38a and a second bottom surface 39b connected to the second side wall surface 38b. Each of the first bottom surface 39a and the second bottom surface 39b is a crystal surface of a crystal crystal.

  As shown in FIG. 5, a plurality of protrusions 40 are formed in the groove portion 37. The plurality of protrusions 40 are arranged from the distal end to the proximal end of the groove portion 37. The plurality of protrusions 40 are arranged in a line at substantially equal intervals along the longitudinal direction L in a state of being separated from the side wall surface 38 (see FIG. 6) of the groove portion 37. The top 41 of the protrusion 40 is formed in a circular shape in plan view, and is disposed so as to be positioned at the center in the width direction W of the groove 37. In addition, the planar view shape of the top part 41 of the projection part 40 is not limited to circular shape, For example, a rectangular shape may be sufficient.

7 is a cross-sectional view taken along line VII-VII in FIG.
As shown in FIG. 7, the protrusion 40 is formed on the bottom 39 of the groove 37 and protrudes in the thickness direction T. The top 41 of the protrusion 40 is located on the same plane as the one main surface 31 c of the first vibrating arm 31. When viewed from the longitudinal direction L, the side surface on one side in the width direction W of the protrusion 40 has a lower half portion connected to the first bottom surface 39a formed substantially parallel to the second bottom surface 39b and connected to the top portion 41. The upper half is formed substantially parallel to the second side wall surface 38b. Further, as viewed from the longitudinal direction L, the other side surface in the width direction W of the protrusion 40 is formed such that the lower half connected to the second bottom surface 39b is substantially parallel to the first bottom surface 39a and The upper half to be connected is formed substantially parallel to the first side wall surface 38a.

  As shown in FIG. 5, the opening area of the groove 37 is reduced in the vicinity of the protrusion 40 compared to other regions. For this reason, when the groove portion 37 is formed by, for example, wet etching, the opening area of the etching mask is locally narrowed around the region where the protrusion portion 40 is formed, and the etching rate tends to decrease. It is in. Accordingly, the bottom 39 of the groove 37 around the protrusion 40 shown in FIG. 7 is shallower than the bottom 39 of the groove 37 in the intermediate part between the adjacent protrusions 40 shown in FIG.

  As shown in FIGS. 6 and 7, two systems of first excitation electrodes 51 and second excitation electrodes that vibrate the vibration arm portions 31 and 32 in the width direction W are provided on the surfaces of the vibration arm portions 31 and 32. 52 is provided. Specifically, the first excitation electrode 51 is provided on the groove portion 37 and the protrusion 40 of the first vibrating arm portion 31 and on both side surfaces of the second vibrating arm portion 32. The second excitation electrode 52 is provided on both side surfaces of the first vibrating arm portion 31 and on the groove portion 37 and the protruding portion 40 of the second vibrating arm portion 32. The excitation electrodes 51 and 52 are patterned in a state where they are electrically insulated from each other, and are arranged so as to vibrate the vibrating arm portions 31 and 32 at a predetermined frequency.

As shown in FIG. 5, the base portion 35 integrally connects the base ends 31 b and 32 b of the vibrating arm portions 31 and 32. The base 35 extends in the width direction W to the outside of the vibrating arm portions 31 and 32.
The support arm portions 33 and 34 are integrally connected to both ends of the base portion 35 in the width direction W, respectively. The support arm portions 33 and 34 extend in parallel to each other along the longitudinal direction L.

Mounted electrodes (not shown) are provided on the surfaces of the support arm portions 33 and 34 as mount portions when the piezoelectric vibrating reed 3 is mounted on the package 2. Each mount electrode is disposed in the vicinity of the tip of each support arm portion 33, 34.
The two types of mount electrodes and the respective excitation electrodes 51 and 52 (see FIG. 6) are electrically connected by routing electrodes (not shown). The routing electrode is formed on a path from each of the support arm portions 33 and 34 to each of the vibrating arm portions 31 and 32 via the base portion 35.

  As shown in FIGS. 2 to 4, the piezoelectric vibrating reed 3 configured as described above is accommodated in the cavity C of the hermetically sealed package 2. Each mount electrode (not shown) of the piezoelectric vibrating reed 3 is electrically and mechanically joined to two electrode pads 20A and 20B provided on the mounting portions 14A and 14B of the package 2 via a conductive adhesive. Has been. Thus, the piezoelectric vibrating reed 3 is cantilevered at the base ends 31 b and 32 b of the vibrating arm portions 31 and 32 via the base 35.

  In addition, it is also possible to use a metal bump instead of a conductive adhesive as a conductive bonding material for bonding each mount electrode to the electrode pads 20A and 20B. The common point between the conductive adhesive and the metal bump is that it is a conductive bonding material having fluidity in the initial stage of bonding and solidifying in the latter stage of bonding to exhibit bonding strength.

  When a predetermined voltage is applied to the external electrodes 21A and 21B (see FIG. 3), a current flows through the excitation electrodes 51 and 52, and an electric field is generated between the excitation electrodes 51 and 52. The vibrating arm portions 31 and 32 vibrate at a predetermined resonance frequency in a direction (width direction W), for example, approaching and separating from each other by an inverse piezoelectric effect caused by an electric field generated between the excitation electrodes 51 and 52. The vibrations of the vibrating arm portions 31 and 32 are used as a time source, a control signal timing source, a reference signal source, and the like.

As described above, the piezoelectric vibrating reed 3 according to the present embodiment is formed on each of the vibrating arm portions 31 and 32, is recessed in the thickness direction T and extends along the longitudinal direction L, and a bottom portion 39 of the groove 37. And a plurality of protrusions 40 protruding in the thickness direction T.
According to this configuration, by providing the protrusions 40 in the groove portions 37, the opening area of the etching mask when forming the groove portions 37 is reduced, so that the etching rate around the protrusion portions 40 is reduced when forming the groove portions 37. The depth of the groove 37 around the protrusion 40 can be reduced. For this reason, the cross-sectional area of each vibration arm part 31 and 32 can be increased in the position where the projection part 40 was formed. Therefore, the strength of the vibrating arm portions 31 and 32 can be improved while the CI value is reduced by providing the groove portion 37.

  In addition, since the protrusion 40 is disposed in a state of being separated from the side wall surface 38 of the groove 37, the protrusion is formed so as to cross the groove in the width direction in order to increase the strength of the vibrating arm. In comparison, a decrease in the area of the side wall surface 38 can be suppressed. Thereby, the area of each excitation electrode 51 and 52 on the side wall surface 38 of the groove part 37 can be ensured large, and the electric field produced between each excitation electrode 51 and 52 provided on the side surface of each vibration arm part 31 and 32 is obtained. Therefore, it is possible to suppress the CI value from increasing.

  Furthermore, since the protrusion 40 is divided into a plurality and formed in the groove 37, for example, the opening area of the groove 37 increases as compared with a configuration in which the protrusion extends along the longitudinal direction of the groove. For this reason, the photoresist applied when patterning the excitation electrodes 51 and 52 easily enters the groove portion 37. Therefore, the manufacturing efficiency of the piezoelectric vibrating piece 3 can be improved.

  The plurality of protrusions 40 are arranged side by side along the longitudinal direction L. Thereby, since the arrangement direction of the plurality of projecting portions 40 and the longitudinal direction of the groove portion 37 coincide with each other, the strength of the portion where the groove portion 37 is formed can be improved uniformly.

  Since the piezoelectric vibrator 1 of the present embodiment includes the piezoelectric vibrating piece 3, the strength of the vibrating arm portions 31 and 32 can be improved while reducing the CI value.

[First Modification]
(Piezoelectric vibrating piece)
Next, a first modification of the present embodiment will be described.
FIG. 8 is an explanatory diagram of the piezoelectric vibrating piece according to the first modification, and is a cross-sectional view of a portion corresponding to the line VII-VII in FIG. 5.
In the embodiment shown in FIG. 7, the protrusion 40 is arranged such that the top 41 is located at the center in the width direction W of the groove 37. On the other hand, in the first modified example shown in FIG. 8, the protrusion 40 is arranged such that the top 41 is positioned on the second side wall surface 38 b side with respect to the central portion in the width direction W of the groove 37. This is different from the embodiment shown in FIG. In addition, about the structure similar to embodiment shown in FIG. 7, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

As shown in FIG. 8, the plurality of protrusions 40 are formed closer to the second side wall surface 38 b than the center of the groove 37 in the width direction W.
Here, since the first side wall surface 38a has a larger inclination angle with respect to the thickness direction T than the second side wall surface 38b, the thickness of the side walls located on both sides in the width direction W is larger than that of the side wall having the first side wall surface 38a. However, the side wall having the second side wall surface 38b is thinner. For this reason, the cross-sectional areas of the vibrating arm portions 31 and 32 are different on both sides across the central portion in the width direction W, and the strength of the vibrating arm portions 31 and 32 is also on both sides across the central portion in the width direction W. There is a difference.
According to the above configuration, since the protrusion 40 is formed on the second side wall surface 38b side with respect to the central portion of the groove portion 37, the cross-sectional areas of the vibrating arm portions 31 and 32 are sandwiched between the central portions in the width direction W. Can be equivalent on both sides. Therefore, the strength of the vibrating arm portions 31 and 32 can be made equal on both sides of the central portion in the width direction W, and the strength of the vibrating arm portions 31 and 32 can be further improved.

  Further, since the cross-sectional areas of the vibrating arm portions 31 and 32 are equal on both sides across the central portion in the width direction W, the vibrating arm portions 31 and 32 vibrate symmetrically in the width direction W. Thereby, the vibration blur of each vibration arm part 31 and 32 is suppressed, and a vibration can be stabilized. Therefore, the vibration characteristics of the piezoelectric vibrating piece can be improved.

[Second Modification]
(Piezoelectric vibrating piece)
Next, a second modification of the present embodiment will be described.
FIG. 9 is an explanatory diagram of the piezoelectric vibrating piece according to the second modified example, and is a cross-sectional view taken along a line VII-VII in FIG.
In the embodiment shown in FIG. 7, the top 41 of the protrusion 40 is located on the same plane as the main surfaces 31 c and 32 c of the vibrating arm portions 31 and 32. On the other hand, in the second modified example shown in FIG. 9, the top portion 141 of the projection 140 is formed lower than the main surfaces 31c, 32c of the vibrating arm portions 31, 32, as shown in FIG. It is different from the embodiment. In addition, about the structure similar to embodiment shown in FIG. 7, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

As shown in FIG. 9, a protrusion 140 is formed on the bottom 39 of the groove 37. The top portion 141 of the protrusion 140 is located closer to the bottom 39 than the main surfaces 31 c and 32 c of the vibrating arm portions 31 and 32.
According to the above configuration, since the protrusion 140 is formed lower than the main surfaces 31c and 32c of the vibrating arm portions 31 and 32, the unevenness in the groove portion 37 is reduced. This makes it easier for the photoresist to enter the bottom 39 of the groove 37 when the excitation electrodes 51 and 52 are patterned. Therefore, the manufacturing efficiency of the piezoelectric vibrating piece can be improved.

[Third Modification]
(Piezoelectric vibrating piece)
Next, a third modification of the present embodiment will be described.
FIG. 10 is a plan view of a piezoelectric vibrating piece according to a third modification.
In the embodiment shown in FIG. 5, the plurality of protrusions 40 are disposed at substantially equal intervals along the longitudinal direction L from the distal end to the proximal end of the groove portion 37. On the other hand, in the 3rd modification shown in FIG. 10, the some projection part 40 is arrange | positioned so that the space | interval of adjacent projection parts 40 may become narrow as it goes to the base end from the front-end | tip of the groove part 37. FIG. This is different from the embodiment shown in FIG. In addition, about the structure similar to embodiment shown in FIG. 5, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

As shown in FIG. 10, in the piezoelectric vibrating piece 103, the plurality of protrusions 40 are arranged so that the interval between the adjacent protrusions 40 is narrowed from the distal end of the groove portion 37 toward the base end.
In general, the stress acting on the bending vibrating arm portions 31 and 32 increases as the tip ends 31a and 32a move toward the base ends 31b and 32b. According to the above configuration, since the plurality of protrusions 40 are arranged so as to become denser from the distal end of the groove portion 37 toward the proximal end, the strength of the vibrating arm portions 31 and 32 is set to the distal ends 31a and 32a. It can be increased as it goes from the base end 31b to the base end 32b. Accordingly, the strength of the vibrating arm portions 31 and 32 can be further improved.

The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, the shape of the piezoelectric vibrating reed 3 is not limited to the above shape, and the vibrating arm portions 31 and 32 extend in a direction inclined at a maximum of about 5 degrees with respect to the longitudinal direction L. Also good.

  In the above embodiment, the piezoelectric vibrating reeds 3 and 103 are so-called side arm type vibrating reeds in which the support arm portions 33 and 34 are disposed outside the resonating arm portions 31 and 32. However, the present invention is not limited to this, and the piezoelectric vibrating piece is, for example, a so-called center arm type vibrating piece in which one supporting arm portion is disposed between a pair of vibrating arm portions, or a so-called tuning fork without a supporting arm portion. A vibrating piece of a mold may be used.

  In the above-described embodiment, the ceramic package type surface-mount type vibrator has been described as the piezoelectric vibrator 1 using the piezoelectric vibrating piece 3. However, the piezoelectric vibrating piece 3 is formed of a glass substrate and a base substrate. The present invention can also be applied to a glass package type piezoelectric vibrator in which a lid substrate is bonded by anodic bonding.

  In addition, it is possible to appropriately replace the components in the above-described embodiments with known components without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator 3,103 ... Piezoelectric vibration piece 31 ... 1st vibration arm part (vibration arm part) 31b, 32b ... Base end of vibration arm part 31c, 32c ... Main surface of vibration arm part 32 ... 2nd vibration arm Part (vibrating arm part) 35 ... base part 37 ... groove part 38 ... side wall surface 38a ... first side wall face (one side wall face) 38b ... second side wall face (the other side wall face) 39 ... bottom part 40, 140 ... projection part L ... longitudinal direction T ... thickness direction W ... width direction

Claims (4)

A pair of vibrating arms arranged side by side and extending;
A base for connecting the base ends of the pair of vibrating arms; and
A groove formed on the pair of vibrating arms, recessed in the thickness direction of the vibrating arms and extending along the longitudinal direction of the vibrating arms;
A plurality of protrusions formed at the bottom of the groove and protruding in the thickness direction of the vibrating arm;
With
The bottom part of the groove part around the protrusion part is shallower than the bottom part of the groove part in the intermediate part between the adjacent protrusion parts,
The plurality of protrusions are arranged so that the interval between the adjacent protrusions is narrowed from the front end to the base end of the groove . A pair of vibrating arms arranged side by side and extending;
A base for connecting the base ends of the pair of vibrating arms; and
A groove formed on the pair of vibrating arms, recessed in the thickness direction of the vibrating arms and extending along the longitudinal direction of the vibrating arms;
A plurality of protrusions formed at the bottom of the groove and projecting in the thickness direction of the vibrating arm,
Further, the groove portion includes a pair of side wall surfaces formed on both sides in the width direction of the vibrating arm portion,
Of the pair of side wall surfaces, one of the side wall surfaces is largely inclined with respect to the thickness direction of the vibrating arm portion than the other side wall surface,
The plurality of protrusions are formed on the other side wall surface side than the central part of the groove part in the width direction of the vibrating arm part.
A piezoelectric vibrating piece characterized by that. A pair of vibrating arms arranged side by side and extending;
A base for connecting the base ends of the pair of vibrating arms; and
A groove formed on the pair of vibrating arms, recessed in the thickness direction of the vibrating arms and extending along the longitudinal direction of the vibrating arms;
A plurality of protrusions formed at the bottom of the groove and projecting in the thickness direction of the vibrating arm,
The plurality of protrusions are formed lower than the main surface of the vibrating arm portion.
A piezoelectric vibrating piece characterized by that. The piezoelectric vibrator, characterized in that it comprises a piezoelectric resonator element according to any one of claims 1 to 3.

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