JP2007158566A - Piezoelectric vibration chip and piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibration chip which is hard to interfere with a package without spoiling CI (crystal impedance) property, and a piezoelectric device using it. <P>SOLUTION: The piezoelectric vibration chip 31 is formed by piezoelectric material to create an outline shape of a rectangle or a square shape, and is very small; chamfers 48 are formed which are beveled corners of the outline shape by etching; and the piezoelectric vibration chip is configured to avoid interference with the package which is a containing body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a piezoelectric vibrating piece housed in a box-shaped package and an improvement of a piezoelectric device containing the piezoelectric vibrating piece.

Piezoelectric devices such as piezoelectric vibrators and piezoelectric oscillators in small information devices such as HDDs (hard disk drives), mobile computers, IC cards, and mobile communication devices such as mobile phones, car phones, and paging systems Is widely used.
A conventional piezoelectric device accommodates, for example, a piezoelectric vibrating piece formed of a piezoelectric material in a package.
The piezoelectric vibrating piece is formed, for example, by etching a quartz wafer into a rectangular shape and providing a driving electrode.

The piezoelectric device having such a configuration is generally configured as shown in FIG.
That is, FIG. 10 is a schematic plan view in which the lid of the piezoelectric device 1 is omitted.
In the figure, a piezoelectric device 1 has a configuration in which a piezoelectric vibrating piece 4 is accommodated in a package 2 and joined.

Specifically, the package 2 is a shallow box-shaped container, and on the upper bottom surface of the package 2,
Connection electrode portions 7 and 7 are formed. The connection electrode portions 7 are connected to mounting terminals on the bottom surface of the package 2 (not shown).
The piezoelectric vibrating piece 4 is, for example, a rectangular AT-cut vibrating piece, and on the front and back main surfaces, an excitation electrode 5 that is a driving electrode and lead electrodes 6 and 6 connected to the excitation electrode 5 are formed. Has been. The lead electrodes 6 and 6 are formed so as to also wrap around the back surface. The conductive adhesives 8 and 8 are applied on the electrode portions 7 and 7 in the package 2, and the piezoelectric vibrating reed 4 is drawn on the conductive adhesives 8 and 8. Electrodes 6, 6
Are bonded by curing the conductive adhesive.

By the way, recently, especially such a piezoelectric device 1 has been extremely miniaturized, and the piezoelectric vibrating reed 4 has an X-direction dimension of 1.5 mm, a Z-direction dimension of 1.0 mm, and a Y-direction dimension. An extremely small piezoelectric vibrating piece having a dimension (thickness t) of about 60 μm is also being made.
Further, not only the piezoelectric vibrating piece but also the entire piezoelectric device is downsized, the package 2 is also extremely downsized.
As a result, the size of the cavity 2a of the package 2 is not particularly large, and in the joining work of the piezoelectric vibrating reed 4 described above, the corners 4a and the like interfere with the inner surface of the package 2 and the work is extremely difficult. In addition, there is a disadvantage that a part of the end portion of the piezoelectric vibrating reed 4 is joined with an extremely inappropriate inclination posture while interfering with the inner surface of the package 2.
In the worst case, when the piezoelectric vibrating piece is joined, the piezoelectric vibrating piece may hit the corner portion of the package 2 and be damaged, resulting in the oscillation stop of the piezoelectric vibrating piece.

In order to prevent interference between the corners of the piezoelectric vibrating reed 4 and the inside of the package 2, it can be considered to remove the corners.
Although it is not always known to process a piezoelectric vibrating piece for such a purpose, FIG. 1 shows a technique for chamfering in a manufacturing process for forming a piezoelectric vibrating piece for other purposes.
1 is known (see Patent Document 1).
First, an element piece for forming a piezoelectric vibrating piece is formed. This piece is obtained by cutting a crystal wafer vertically and horizontally, lapping the surface, making a strip-shaped blank, fixing each blank in a polymerized state with an adhesive or the like, and attaching a blank processing block 4-1. Form.
Then, when the machining block 4-1 is placed in the cylindrical pipe 9 of FIG. 11 and the cylindrical pipe 9 is rotated in the direction of the arrow, the ridgelines of the individual pieces constituting the machining block 4-1 are polished and chamfered. It is what is done.

However, the piezoelectric vibrating piece handled by the technology of Patent Document 1 has a large size,
Therefore, a polishing technique using a cylindrical pipe 9 or the like is used. However, the piezoelectric vibrating reed 4 as described above is extremely small, and is not a size that can be formed by dicing a wafer like the blank of Patent Document 1 itself. For example, by etching a quartz wafer, the outer shape can be extracted to form a large number simultaneously.
Therefore, it is very small and cannot be machined or polished.

Patent Document 2 describes that a corner portion of a piezoelectric vibrating piece is processed by etching instead of machining or polishing.
In a small piezoelectric vibrating piece as the object of the present invention, if it is impossible to process such as polishing because it is small, a method of processing by such etching is also conceivable.

JP-A-10-209786 JP 2003-318697 A

However, Patent Document 2 described above describes that the end face in the X-axis direction of the piezoelectric vibrating piece is chamfered by etching.
In this document, the CI (crystal impedance) value can be improved by performing such etching even for a small resonator element, as in the conventional convex processing.
However, in this method, if the end face in the X-axis direction of the piezoelectric vibrating piece is chamfered by etching, the same effect as the convex process can be obtained as understood from the completed form. It is not a chamfer.
In particular, in Patent Document 2, the corner portion of the resonator element 1 shown in FIGS. 1 and 4 has a large R chamfer. However, if etching is performed with such an extreme amount, the influence of etching anisotropy is exerted. It has been confirmed by the present inventor that the strength of the CI value characteristic is impaired.

SUMMARY An advantage of some aspects of the invention is to provide a piezoelectric vibrating piece that does not easily interfere with a package without impairing CI value characteristics, and a piezoelectric device using the same.

According to the first aspect of the present invention, the first invention is an extremely small piezoelectric vibrating piece formed of a piezoelectric material so as to have a rectangular or square outer shape, and a chamfered portion in which corner portions of the outer shape are chamfered by etching. This is achieved by the piezoelectric vibrating piece configured to avoid interference with the package as the container.

According to the configuration of the first invention, the corners of the outer shape of a very small piezoelectric vibrating piece that cannot be machined such as polishing are chamfered by etching. As a result, when the piezoelectric vibrating reed is accommodated in a space having a very small clearance such as a package as a container, the inside of the package and the corner of the piezoelectric vibrating reed are precisely joined without interference. .
In particular, when using a process of forming a plurality of pieces of piezoelectric vibrating reeds by etching a piezoelectric substrate such as a quartz wafer of a predetermined size, a photomask used in the outer shape processing step by the etching If the part corresponding to the corner portion is made to correspond to the chamfered shape, chamfering is performed at the same time as the outer shape processing. Compared to the method, there are significant advantages.
Furthermore, by chamfering only the corners of the piezoelectric vibrating piece, it is effective that extreme etching anisotropy is exerted compared to the conventional method of chamfering the entire end face in the X direction. This can prevent the deterioration of the CI value characteristics.

According to a second invention, in the configuration of the first invention, the chamfered portion is chamfered to such an extent that the CI value characteristic is not deteriorated by etching anisotropy.
According to the configuration of the second invention, when chamfering the corner portion of the piezoelectric vibrating piece, the processing considering the CI value characteristic is performed, thereby facilitating the joining and at the same time preventing the deterioration of the performance. be able to.

According to a third aspect of the invention, in the configuration of the first or second aspect of the invention, the piezoelectric vibrating piece has a base part joined to the package side and a part mainly involved in vibration on the tip side from the base part. The chamfered portion is formed only at both corners at the end on the tip side.
According to the configuration of the third invention, when the tip portion is not joined / fixed to the package side, the tip portion is provided inside the package or the like by providing a chamfered portion at a corner portion of the tip portion. It is possible to effectively prevent the horizontal joining posture from being disturbed.

A fourth invention is characterized in that, in the configuration of either the first or second invention, the chamfered portions are formed at corners of four corners of the piezoelectric vibrating piece.
According to the configuration of the fourth aspect of the invention, by providing the chamfered portion for all the corner portions of the piezoelectric vibrating piece, there is no corner portion that contacts the inside of the package at the time of joining work to the package or the like. Is the most effective.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect, the chamfered portion formed at both corners on the base side joined to the package side among the corners of the four corners is formed at both corners of the tip. The chamfered portion is larger than the portion.
According to the configuration of the fifth aspect of the invention, the region to which the piezoelectric vibrating piece is joined hardly participates in vibration, so even if the chamfered portion of this portion is enlarged, the performance is hardly adversely affected. By having the portion, it is possible to effectively prevent interference with the inner surface of the package.

According to a sixth aspect of the present invention, in the configuration of the first or second aspect, the chamfered portion is formed only at both corners on the base side joined to the package side of the piezoelectric vibrating piece. .
According to the configuration of the sixth invention, the region to which the piezoelectric vibrating piece is joined hardly participates in the vibration. Therefore, by forming the chamfered portion only in this portion, the vibration performance is not adversely affected.
A structure that effectively prevents interference with the inner surface of the package can be obtained.

According to a seventh aspect of the present invention, there is provided a piezoelectric device in which a very small piezoelectric vibrating piece is accommodated in a package or a case, wherein the piezoelectric vibrating piece has a rectangular or square outer shape made of a piezoelectric material. And a chamfered portion in which a corner portion of the outer shape is chamfered by etching so as to avoid interference with a package as a container.

1 and 2 show a first embodiment of a piezoelectric device according to the present invention. FIG. 1 is a schematic plan view of a piezoelectric device in which an internal structure is exposed except for a lid, and FIG. FIG. 6 is a schematic end view taken along the line A, and shows a lid disposed.
In these drawings, the piezoelectric device 30 shows an example in which a piezoelectric vibrator is configured, and the piezoelectric device 30 accommodates a piezoelectric vibrating piece in a package 36.
Specifically, as shown in FIG. 2, the piezoelectric device 30 houses the piezoelectric vibrating piece 31 in a package 36 including a first substrate 34 and a second substrate 35 laminated on the first substrate 34. is doing.

The first substrate 34 constituting the package 36 is an insulating base, and the electrode part 32 is formed thereon. In FIG. 1, as indicated by reference numerals 32 and 32, a pair of electrode portions is provided at both end portions in the width direction of the first substrate 34 at the end portion of the package 36.
The first substrate 34 and the second substrate 35 are formed of an insulating material, and ceramic is suitable. In particular, as a preferable material, it coincides with the thermal expansion coefficient of the piezoelectric vibrating piece 31 or a lid described later, or
A material having a very close thermal expansion coefficient is selected. In this embodiment, for example, a ceramic green sheet is used. The green sheet is obtained, for example, by dispersing a ceramic powder in a predetermined solution, forming a kneaded product formed by adding a binder into a sheet-like long tape shape, and cutting it into a predetermined length Is.

The first substrate 34 and the second substrate 35 can be formed by laminating and sintering green sheets molded into the illustrated shape. In this case, the first substrate 34 is a substrate that constitutes the bottom of the package 36, and the second substrate 35 that is stacked on the first substrate 34 has a frame shape by removing the internal material from the above-described green sheet as a plate shape. As shown, the internal space S of FIG. 2 is formed, and the piezoelectric vibrating piece 31 is accommodated using the internal space S (see FIG. 3). The package 36 includes a lid 3 made of a metal such as ceramic, glass, or kovar.
7 is joined via a joining material such as a Kovar ring or a sealing material 47. Thereby, the package 36 is hermetically sealed.

On the first substrate 34, for example, after forming a required conductive pattern using a conductive paste such as silver or palladium or a conductive paste such as tungsten metallization, the first and second substrates are sintered. Thereafter, nickel and gold or silver are sequentially plated to form the electrode portions 32 and 32 described above. As shown in FIG.
The mounting terminals 41 and 41 exposed on the bottom surface of the package 36 are connected by a conductive pattern (not shown). The conductive pattern for connecting the electrode portion 32 and the mounting terminal 41 may be formed on the surface of a castellation (not shown) used when the package 36 is formed, and the outer surface of the package 36 may be routed. Alternatively, the connection may be made by a conductive through hole (not shown) penetrating the first substrate 34.

As will be described later, the piezoelectric vibrating piece 31 is obtained by processing, for example, a wafer formed of a piezoelectric material into a thin rectangle or square. The piezoelectric vibrating piece 31 is extremely small. For example, in FIG. 1, the dimension in the X (electrical axis) direction is 1.5 mm, the dimension in the Z (optical axis) direction is 1.0 mm, and the dimension in the Y (mechanical axis) direction. The dimension (thickness t) is about 60 μm.
Specifically, the piezoelectric material forming the piezoelectric vibrating piece 31 is a quartz wafer made of quartz as a piezoelectric substrate, and the quartz wafer is parallel to the X axis (electrical machine axis) of the quartz,
Moreover, a quartz substrate having a cut surface with respect to the Z axis (optical axis) is used.
In this case, the crystal wafer is cut out from the single crystal of the crystal so that the X axis is the electric axis, the Y axis is the mechanical axis, and the Z axis is the optical axis. In addition, when cutting from a single crystal of quartz, an AT-cut quartz plate cut out at a predetermined angle, for example, 35.15 degrees from the Z axis in the above-described orthogonal coordinate system consisting of the X, Y, and Z axes. The drive electrode which will be described later is formed. As other piezoelectric materials, for example, piezoelectric materials such as lithium tantalate and lithium niobate can be used in addition to quartz. Further, the shape of the piezoelectric chip is not limited to the flat type, and a convex type or a reverse mesa type resonator element can be used.

In FIG. 1, an excitation electrode 51 is formed as a main electrode for driving on the surface of a piezoelectric chip which is an individual piece of a vibrating piece. The excitation electrode 51 is formed in a region where the piezoelectric chip is actively vibrated, and applies a driving voltage to the piezoelectric material, thereby efficiently generating an electric field in the material and exciting the material. The excitation electrode 51 is also formed in the same form on the back surface of a piezoelectric chip (not shown), and is an extraction electrode that is a connection electrode formed at each end in the width direction at the end in the length direction of the piezoelectric vibrating piece 31. 51a and 51a are connected separately. Each extraction electrode 51a, 51a goes around the side surface of the piezoelectric chip and is also formed on the back surface.

As shown in FIG. 1, such a piezoelectric vibrating piece 31 is formed by applying conductive adhesives 43 and 43 on the respective electrode portions 32 and 32 on the package 36 side, and then on the piezoelectric vibrating piece 31. The base part or one end part 31a on which the respective extraction electrodes 51a and 51a described in FIG. 1 are formed is placed, and these conductive adhesives 43 and 43 are cured to be joined in a cantilever manner.
As a result, the drive voltage supplied from the outside of the package 36 via the mounting terminals 41, 41 is transmitted from the electrode portions 32, 32 on the package 36 side to the conductive adhesives 43, 43 and the extraction electrodes 51 a of the piezoelectric vibrating reed 31. It is applied to the excitation electrode 51 via 51a. Therefore,
The distal end side 31b of the piezoelectric vibrating piece 31 is driven by being vibrated by a piezoelectric action.

Here, as the conductive adhesives 43, 43, a binder component made of a predetermined synthetic resin,
What added electroconductive particles, such as silver particle, can be used. Further, the piezoelectric vibrating piece 31 is not necessarily a cantilever type, and a part of the front end side 31b is provided on the package 36 side, not shown.
It is good also as a structure mounted on the stand called a pillow.

Further, as shown in FIG. 1, chamfered portions 48, 48 are provided by chamfering the corner portion on the tip end side of the piezoelectric vibrating piece 31 by etching as will be described later. That is, in this embodiment, a corner portion of the outer shape of a very small piezoelectric vibrating piece that cannot be machined such as polishing is chamfered by etching.
For this reason, the space S having a very small clearance of the package 36 which is a container.
In addition, when the piezoelectric vibrating piece 31 is accommodated, the concave corner portions 36a, 36a of the package 36 and the corners of the piezoelectric vibrating piece 31 are precisely joined without interference.
Further, by chamfering only the corners of the piezoelectric vibrating piece 31, the entire end surface in the X direction is changed to C
Compared with the conventional method of chamfering, it is possible to effectively prevent the influence of extreme etching anisotropy and to prevent the deterioration of the CI value characteristics.

Next, a method for producing such a small piezoelectric vibrating piece 31 will be briefly described.
FIG. 3 is a flowchart showing an example of a method for manufacturing the piezoelectric vibrating piece 31, FIGS. 4 and 5 are process diagrams sequentially showing an example of a manufacturing process of the piezoelectric vibrating piece 31, and FIG. 6 shows a number of piezoelectric vibrating pieces from a quartz wafer. It is a figure which shows a mode that it manufactures.
As described above, the crystal wafer 56 in FIG. 3A is cut out from a crystal single crystal so that the crystal axis of the crystal is the electric axis, the Y axis is the mechanical axis, and the Z axis is the optical axis. It has been.
The quartz wafer 56 is first cleaned with pure water (ST11), and as shown in FIG. 4B, a base chromium layer 52 is formed on the surface of the quartz wafer 56 by sputtering or vacuum deposition. Further, a gold layer 53 is formed on the surface (ST12).

Subsequently, a resist 54 is applied to the surface of the gold layer (ST13). As the resist 54,
For example, OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd. is used.
The resist 54 is exposed and developed (ST14, ST15), and an opening 54a is formed as shown in FIG. A chamfer forming opening 54b corresponding to the chamfered portion 48 of FIG. 1 is formed in a part of the opening 54a.
Next, the gold layer 53 is wet etched using, for example, iodine and an alkali iodide solution, and then the chromium layer 52 is etched using a ceric ammonium nitrate solution (ST16).

In this way, the exposed quartz portion as shown in FIG. 5D is wet-etched using a hydrofluoric acid solution or the like (ST17). As a result, the state shown in FIG.
The outer shape 55 is separated. Subsequently, the resist 54 is peeled off, and the gold layer 53 and the chromium layer 52 are sequentially peeled off (ST18, ST19). As a result, as shown in FIG.
6, the piezoelectric chip 31-1, which is an individual piece of a large number of vibrating pieces, is formed at the same time.
By performing an appropriate photolithography process in the peeling process of T19, electrodes such as an excitation electrode and an extraction electrode can be formed, and the piezoelectric vibrating piece 31 can be formed.
Thus, when a large number of piezoelectric vibrating reeds 31 are simultaneously formed by etching, the chamfered portion 48 is formed.
Can also be formed at the same time.

FIG. 7 is a schematic plan view showing a second embodiment of the piezoelectric device, and the portions denoted by the same reference numerals as those in FIG. Explained.
In the piezoelectric device 30-1 in FIG. 7, chamfered portions 48 and 48 are formed at the corners of the four corners of the piezoelectric vibrating piece 31.
, 49, 49 are formed. That is, as compared with the case of FIG. 1, chamfered portions 49 and 49 are also added to portions corresponding to the concave corner portions 36 b and 36 b of the package 36.
Thereby, since all the corners of the piezoelectric vibrating piece 31 do not interfere with the inside of the package 36, there is no corner that contacts the inside of the package at the time of joining work.

FIG. 8 is a diagram illustrating the relationship between the chamfering amount (indicated by the dimension indicated by the symbol K in FIG. 1) and the CI value when the piezoelectric vibrating piece has the above-described dimensions.
When chamfering is performed by etching, the corners are chamfered as in the past, and X
If the direction end face is chamfered, the influence of the etching anisotropy of the crystal is increased correspondingly, and a deformed portion is formed as a burr. When the etching amount is large, that is, when the R (curved surface) shape is large, an etched surface having a crystal orientation appears continuously at each position on the curved surface, so that burrs increase and the CI value increases as shown in the figure.
Also, as shown in the figure, when the chamfering amount is 300 μm or less, the increase in the CI value is relatively small, and the increase in the CI value can be further suppressed when 100 <K <300 (μm). In addition, when the K is smaller than 100 μm, the increase in the CI value is the smallest.
As described above, when forming the chamfered portion, it is preferable that the chamfered portion is not cut into an R shape as much as possible, but is cut in a straight line. As a chamfered portion cut off linearly, the analysis becomes easy.

FIG. 9 is a schematic plan view showing a third embodiment of the piezoelectric device, and portions having the same reference numerals as those in FIG. Explained.
In the piezoelectric device 30-2 of FIG. 9, not only chamfered portions are formed at the corners of the four corners of the piezoelectric vibrating piece 31, but also both corners on the base 31a side to be joined to the package 36 side among the corners of the four corners. The chamfered portions 49-1 and 49-1 formed at the upper portion are larger chamfered portions than the chamfered portions 48 and 48 formed at both corners of the distal end side 31 b.
That is, since the base portion 31a of the piezoelectric vibrating piece 31 is joined, it hardly participates in the vibration. Therefore, even if the chamfered portions 49-1 and 49-1 of this portion are enlarged, the performance is hardly adversely affected. By having a large chamfered portion, interference with the inner surface of the package 36 can be effectively prevented.

In particular, since the chamfered portion 49-1 of the present embodiment has an intersecting surface so as to have a stepped portion, the area of the chamfered portion is increased and the bonding strength with the conductive adhesive 43 is improved. be able to.

Although not shown in the drawings, for the same reason as described above, if chamfered portions are provided only at both corners on the base 31a side of the piezoelectric vibrating piece 31, the chamfered portions are formed at all corners. Compared to the above, it is preferable in that it is inferior in terms of interference with the package 36, but has almost no adverse effect on vibration characteristics such as an increase in CI value.

The present invention is not limited to the above-described embodiment. Each configuration of each embodiment can be appropriately combined or omitted, and can be combined with other configurations not shown.
The present invention can be used not only for an AT-cut piezoelectric vibrating piece, but also for a so-called convex type piezoelectric vibrating piece, an inverted mesa-shaped piezoelectric vibrating piece, and the like.
In addition, the present invention is applicable to all piezoelectric devices regardless of the names of piezoelectric vibrators, piezoelectric oscillators, etc., as long as they use a package as a box-shaped container and accommodate a piezoelectric vibrating piece inside. can do.

1 is a schematic plan view of a piezoelectric device according to a first embodiment of the present invention. The AA cut | disconnection end elevation of FIG. The flowchart which shows an example of the manufacturing process of the piezoelectric device of FIG. FIG. 2 is a process diagram sequentially illustrating a manufacturing process of a piezoelectric vibrating piece of the piezoelectric device of FIG. 1. FIG. 2 is a process diagram sequentially illustrating a manufacturing process of a piezoelectric vibrating piece of the piezoelectric device of FIG. 1. The figure which shows a mode that many piezoelectric vibrating strips are formed in a quartz wafer by the manufacturing process of the piezoelectric vibrating strips of the piezoelectric device of FIG. The schematic plan view of the piezoelectric device which concerns on the 2nd Embodiment of this invention. The graph which shows the relationship between a chamfering amount and CI value. The schematic plan view of the piezoelectric device which concerns on the 3rd Embodiment of this invention. The schematic plan view which shows the structural example of a piezoelectric device. Explanatory drawing which shows an example in the process of the conventional piezoelectric vibrating piece.

Explanation of symbols

30 ... piezoelectric device, 31 ... piezoelectric vibrating piece, 36 ... package, 48, 49
... Chamfered part, 51 ... Excitation electrode

Claims (7)

An extremely small piezoelectric vibrating piece formed of a piezoelectric material so as to have a rectangular or square outer shape,
A piezoelectric vibrating piece, characterized in that a chamfered portion in which a corner portion of the outer shape is chamfered by etching is provided to avoid interference with a package as a container. 2. The piezoelectric vibrating piece according to claim 1, wherein the chamfered portion is chamfered to such an extent that the CI value characteristic is not deteriorated by etching anisotropy. The piezoelectric vibrating piece has a base part joined to the package side and a part mainly involved in vibration on the tip side from the base part, and the chamfered part is only at both corners at the end part on the tip side. The piezoelectric vibrating piece according to claim 1, wherein the piezoelectric vibrating piece is formed. The piezoelectric vibrating piece according to claim 1, wherein the chamfered portion is formed at corners of four corners of the piezoelectric vibrating piece. The chamfered portion formed at both corners on the base side joined to the package side among the corners of the four corners is a chamfered portion larger than the chamfered portion formed at both corners of the tip. Item 5. The piezoelectric vibrating piece according to Item 4. 3. The piezoelectric vibrating piece according to claim 1, wherein the chamfered portion is formed only at both corners on the base side bonded to the package side of the piezoelectric vibrating piece. 4. A piezoelectric device containing a very small piezoelectric vibrating piece in a package or case,
The piezoelectric vibrating piece is
It is formed to have a rectangular or square outer shape with piezoelectric material,
In addition, the piezoelectric device is characterized in that a chamfered portion in which a corner portion of the outer shape is chamfered by etching is provided so as to avoid interference with a package as a container.

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