JP2008219827A - Piezoelectric vibration chip and piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibration chip in which a wide area occupied by a vibrating portion with respect to a piezoelectric blank can be ensured while avoiding deterioration in frequency characteristics caused by stress. <P>SOLUTION: The piezoelectric vibration chip 10 is equipped with: exciting electrodes 18a, 18b formed of AT cut crystal blank and disposed while being paired on both principal surfaces of the blank; two supporting electrodes 22a, 22b corresponding to the exciting electrodes 18a, 18b, respectively; and conducting electrodes 20a, 20b electrically connecting the exciting electrodes 18a, 18b to the supporting electrodes 22a, 22b. With a crystal axis Y' constituting the AT cut crystal blanks as a reference, a crystal axis X' and a crystal axis Z" obtained by rotating a crystal axis X and a crystal axis Z' at 60°±10° are set around the relevant axis Y', edges of a piezoelectric blank 16 are formed of straight lines in parallel with the crystal axis X' and the crystal axis Z", respectively, and the supporting electrodes 22a, 22b are provided between a vibrating portion, where the exciting electrodes 18a, 18b are formed, on a straight line in parallel with the axis X' and the edge formed in parallel with the axis X'. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric vibrating piece and a piezoelectric device including the piezoelectric vibrating piece, and more particularly to a piezoelectric vibrating piece configured to excite thickness shear vibration and a piezoelectric device including the piezoelectric vibrating piece.

  In recent years, piezoelectric devices that employ a quartz base plate as a piezoelectric vibrating piece have been widely used as clock sources for various electronic devices. In these piezoelectric devices, the element piece needs to be fixed to a package, a substrate, or the like. However, the influence of stress on the fixing of the element piece is a problem.

  For example, as shown in FIG. 10, a general piezoelectric vibrating piece using an AT-cut crystal element plate has two support electrodes 3 arranged in parallel to the edges constituting the piezoelectric element plate 2. The structure supported on the basis of a point is taken. In order to stabilize the fixed state of the piezoelectric vibrating reed 1, a conductive adhesive that is used as a connection member with a package or the like is one that employs a hard binder such as an epoxy or polyimide. It is common.

  In the piezoelectric device mounted with the piezoelectric vibrating piece 1 as described above, not only when the stress is directly applied to the package, but also the influence of the stress on the element piece occurs in the thermal expansion at the time of reflow. Become. For example, a stress applied to the package is transmitted to the element piece via the support member. In addition, the thermal stress inside the element piece is caused by the expansion and contraction that occur during heating and cooling being hindered by the support member that connects members having different linear expansion coefficients.

  Such stress applied to the element piece affects the oscillation frequency and adversely affects various characteristics such as aging characteristics and frequency temperature characteristics. For this reason, various means aimed at eliminating the transmission of stress that affects the oscillation frequency have been proposed. One of those proposals is disclosed in Patent Document 1 and Patent Document 2. The piezoelectric device disclosed in Patent Document 1 has a piezoelectric vibrating piece configured as shown in FIG. The piezoelectric vibrating reed 1a in the piezoelectric device disclosed in Patent Document 1 is characterized in that two support electrodes 3a are arranged on a straight line connecting one edge of the excitation electrode 4a and the piezoelectric element plate 2a. According to Patent Document 1, by arranging the support electrode 3a in such a form, the excitation electrode 4a does not exist in the stress generation direction, that is, between the two support electrodes 3a. It can be avoided.

The piezoelectric vibrating piece mounted on the piezoelectric device disclosed in Patent Document 2 is characterized in that two support electrodes are arranged on a straight line having a predetermined rotation angle with respect to a specific crystal axis. It is what. Specifically, the two support electrodes are arranged on a straight line having a rotation angle of 60 ° or 120 ° from the X axis, which is the crystal axis of the AT-cut quartz base plate, with the Y axis as a base point. The stress applied along the straight line having the rotation angle has a very small sensitivity ratio, and the influence on the vibration part, that is, the influence on the oscillation frequency can be extremely reduced.
JP 2003-332877 A JP 2001-85966 A

  If the piezoelectric vibrating piece has the above-described configuration, it is considered that the influence of stress on the vibrating portion can be suppressed, and various characteristics of the quartz vibrating piece such as aging characteristics and frequency temperature characteristics can be kept good. . However, in each of the piezoelectric vibrating reeds presented in the above document, an electrode pattern is formed so that the vibrating portion and the two supporting electrodes are positioned on one straight line. For this reason, there is a problem in that the area occupied by the vibration part with respect to the area of the piezoelectric element plate is reduced. When the area of the vibration part is reduced, there is a problem that the effect of energy confinement becomes thin and the coupling of the secondary vibration (high-order contour vibration or the like) to the thickness-shear vibration that is the main vibration is likely to occur. The coupling of the secondary vibration appears as a CI dip or a frequency jump, which causes the oscillation stability to be hindered.

  Therefore, in the present invention, a structure of a piezoelectric vibrating piece that can occupy a relatively large area occupied by the vibrating portion with respect to the piezoelectric element plate while avoiding deterioration of frequency characteristics due to stress, and a piezoelectric device equipped with this piezoelectric vibrating piece The purpose is to provide.

  In order to achieve the above object, a piezoelectric vibrating piece according to the present invention is formed of an AT-cut quartz base plate and corresponds to each of the excitation electrodes arranged in pairs on both main surfaces of the base plate and the excitation electrodes. And a conductive electrode for electrically connecting the excitation electrode and the support electrode, the Y axis with reference to a crystal axis Y ′ constituting the AT-cut quartz base plate. Piezoelectricity is generated by two straight lines parallel to the crystal axis X ′ obtained by rotating the crystal axis X and the crystal axis Z ′ around the axis by 60 ° ± 10 ° or 120 ° ± 10 ° and a line intersecting the two straight lines. An edge of the base plate is formed, and the support electrode is disposed between a vibrating part on the straight line parallel to the X′-axis and where the excitation electrode is formed, and an edge formed parallel to the X′-axis. It is provided. With the piezoelectric device having such a configuration, it is possible to avoid deterioration of frequency characteristics due to the influence of stress generated between the support electrodes. In addition, since the two support electrodes are arranged in parallel with the edge of the piezoelectric element plate, the area occupied by the vibration part with respect to the piezoelectric element plate can be made relatively large.

  In the piezoelectric vibrating piece having the above-described configuration, the piezoelectric element plate includes a thin portion that constitutes the vibrating portion and a thick portion that surrounds the thin portion, and the support electrode is provided on the thick portion. It is good to make it. By configuring the vibration part with a thin part, vibration in a high frequency band can be excited. Moreover, the mechanical strength of the piezoelectric vibrating piece can be maintained by surrounding the thin portion with the thick portion.

  In the piezoelectric vibrating piece having the above-described configuration, it is desirable that the two support electrodes be arranged close to each other. By arranging the support electrodes close to each other, the stress generated between the two support electrodes is inevitably reduced. For this reason, the influence given to a vibration part can also be made small.

  In the piezoelectric vibrating piece having the above-described configuration, the support electrode may be disposed along an edge formed in parallel with the X ′ axis. By arranging the support electrode on the edge, the area of the vibration part can be expanded most. If mounting is performed using the cross-sectional shape of the edge formed parallel to the X ′ axis, it is possible to prevent disconnection of the connecting member.

  Furthermore, in the piezoelectric vibrating piece configured as described above, either one of the two support electrodes may be disposed at a corner of the piezoelectric element plate, and the other may be placed close to the corner. According to such a configuration, it is possible to increase the distance from the generation region of the thickness shear vibration, which is the main vibration, to the support electrode. Therefore, it is possible to suppress the influence of the stress generated between the support electrodes on the frequency characteristics.

  In addition, a piezoelectric device according to the present invention is characterized in that any one of the piezoelectric vibrating reeds described above is mounted in a package. If the piezoelectric device is mounted with the piezoelectric vibrating piece having the above-described characteristics, it is possible to prevent the frequency characteristics from being deteriorated due to the influence of stress generated between the support electrodes.

  Furthermore, in the piezoelectric device having the above characteristics, bumps may be used when the piezoelectric vibrating piece is mounted in the package. If bumps are used for mounting the piezoelectric vibrating piece, the distance between the two support electrodes can be made closer.

Hereinafter, embodiments of a piezoelectric vibrating piece and a piezoelectric device according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a piezoelectric vibrating piece according to the first embodiment.
The piezoelectric vibrating piece 10 according to this embodiment includes a piezoelectric element plate 16, excitation electrodes 18 (18 a, 18 b), support electrodes 22 (22 a, 22 b), and conduction electrodes 20 (20 a, 20 a, 20) provided on the piezoelectric element plate 16. 20b) as a basis. The piezoelectric element plate 16 used in the present embodiment forms the piezoelectric element plate 16 with a so-called in-plane rotation angle θ1 with respect to a generally known AT-cut crystal element plate 16a.

  Here, as shown in FIG. 2, the AT-cut quartz base plate 16 a means that the X axis (electric axis), the Y axis (mechanical axis), and the Z axis (optical axis) shown as crystal axes of quartz are Y This is a base plate having a plane obtained by rotating the base plate 16b having a plane perpendicular to the axis about 35 ° around the X axis. Here, the Y-axis and the Z-axis representing the crystal axis of the base plate are denoted as the Y′-axis and the Z′-axis, respectively, because the rotation angles are given around the X-axis.

  The piezoelectric element plate 16 of the present embodiment has the X ′ axis and Z ″ axes obtained by rotating the X axis and Z ′ axis by 60 ° ± 10 ° or 120 ° ± 10 ° around the Y ′ axis, respectively. The edge of the piezoelectric element plate 16 is formed along a straight line parallel to the X ′ axis and the Z ″ axis. In the embodiment described below, the description will be given with an example in which the in-plane rotation angle is 60 ° ± 10 °.

  Here, as shown in FIG. 3, the piezoelectric element plate 16 according to the present embodiment has a thin portion (thin portion) 14 and a thicker portion (thick wall portion) than the thin portion 14. Part) 12. Specifically, a concave portion 14a is formed on one main surface (upper side surface in the case shown in FIG. 3) in the vicinity of the central portion of the piezoelectric element plate 16, and the concave portion 14a forming portion constitutes a vibrating portion. The thin portion 14 is formed. And the site | part which surrounds the circumference | surroundings of this recessed part 14a in frame shape becomes the thick part 12. FIG. The recesses 14a may be formed by wet etching.

  The excitation electrodes 18 are respectively formed on both main surfaces of the thin portion 14 of the piezoelectric base plate 16 having the above-described configuration. This is because, by using the thin portion 14 as a vibration portion and forming the excitation electrode 18 therein, oscillation in a high frequency band is possible. The excitation electrode 18 may be rectangular, circular, or elliptical. The thickness shear vibration, which is the main vibration of the vibration excited by the piezoelectric vibrating piece using the AT-cut piezoelectric element plate, occurs in an elliptical shape in the vibration region, so that the shape of the excitation electrode is circular or elliptical, This is because the oscillation efficiency can be increased.

  The support electrode 22 is disposed along an edge formed in parallel to the X ′ axis in the piezoelectric element plate 16 having the above-described configuration. Here, FIG. 4A shows the relationship between the stress addition angle θ based on the X axis in a general AT-cut quartz base plate (circular) and the stress sensitivity ratio K. FIG. 4B is a block diagram showing how stress is applied to a circular AT-cut quartz plate. From FIG. 4A, it can be read that the stress sensitivity ratio K approaches 0 when the stress addition angle θ is approximately 60 ° or 120 °. That is, it can be understood that the stress applied when the stress application angle is in the direction along the straight line of 60 ° or 120 ° has little influence on the vibration part. The edge of the piezoelectric element plate 16 according to the present embodiment is a straight line obtained by rotating the X axis by 60 ° with the Y ′ axis as a base point. Since the rate of decrease of the stress sensitivity ratio K is determined by the stress application angle, the effect of decreasing the stress sensitivity ratio K is obtained even when the support electrode 22 is arranged along a straight line parallel to the X ′ axis. It can be said that. In other words, even if stress generated by thermal expansion during reflow or impact applied to a package or the like on which the piezoelectric vibrating piece 10 is mounted is transmitted between the support electrodes 22a and 22b, the influence is minimized. Thus, frequency fluctuations can be suppressed.

  Further, the edge formed parallel to the X ′ axis has a convex cross-sectional shape. Conventionally, by arranging the two support electrodes arranged side by side on a straight line connecting the vibration part where the excitation electrode is arranged and the edge, along the edge formed parallel to the X ′ axis, The area of the thick part 12 required for arranging the support electrode 22 can be reduced, and the area occupied by the vibration part can be increased. Thereby, while being able to improve the effect of energy confinement, the coupling | bonding of sub vibrations, such as a higher order outline vibration with respect to the thickness shear vibration which is a main vibration, can be suppressed. In addition, in order to suppress the stress generated in the plane direction between the support electrode 22a and the support electrode 22b, it is desirable to reduce the distance between the two support electrodes 22a and 22b so as to be close to each other. Specifically, the distance between the two support electrodes 22a and 22b may be shorter than the distance between the vibrating portion and the edge formed parallel to the X ′ axis.

  The conductive electrodes 20a and 20b are electrodes that are routed on the piezoelectric element plate 16 in order to electrically connect the excitation electrodes 18a and 18b and the support electrodes 22a and 22b, respectively. Here, since the piezoelectric element plate 16 according to the present embodiment has the in-plane rotation angle θ1 as described above, when the piezoelectric element plate 16 is formed by wet etching, an etching surface in the X′-axis direction is obtained. Furthermore, it has an inclined surface along the crystal direction. Here, in the conventional piezoelectric vibrating piece that does not have the in-plane rotation angle θ, when the inverted mesa structure is adopted, the portion where the side wall between the thin portion and the thick portion becomes an inclined surface is along the X axis. It was a side wall to be formed. In the piezoelectric vibrating piece having no in-plane rotation angle, the support electrode is arranged in the direction along the Z ′ axis. And since the conduction electrode which connects an excitation electrode and a support electrode is pattern-formed avoiding an acute angle part in order to prevent a disconnection of a wiring pattern, it had to lengthen the drawing distance of a conduction electrode. On the other hand, in the piezoelectric vibrating piece 10 according to the present embodiment, an inclined surface is formed on the side wall of the recess 14a parallel to the edge on which the support electrodes 22a and 22b are arranged, and thus the excitation electrode 18a to the support electrode 22a. It is possible to make the routing distance up to the shortest.

  Next, a method for manufacturing the piezoelectric vibrating piece 10 having the above configuration will be described. First, the outer shape of the piezoelectric element plate 16 is formed by wet etching. At this time, if the piezoelectric crystal forming the piezoelectric element plate 16 has an etching rate anisotropy, a convex shape or an inclined surface is formed on the edge of the piezoelectric element plate 16. It becomes.

  That is, the piezoelectric element plate 16 according to the present embodiment, which is an AT-cut crystal element plate having an in-plane rotation angle θ, has a difference in etching rate for each crystal axis with anisotropy in the crystal direction. Specifically, as described above, the edge formed parallel to the X′-axis has a shape in which the central portion in the thickness direction protrudes compared to the both end portions, that is, a convex shape. In addition, the edge formed in parallel with the Z ″ axis forms an inclined surface that is substantially vertical or has an acute angle at the boundary with one of the main surfaces.

  Note that a known technique may be used for the outer shape formation by wet etching. That is, stepwise processes such as a resist film forming process on a piezoelectric wafer (not shown), an exposure process using a mask, a developing process using a developer, an etching process using an etching liquid, and a resist film removing process. After that, shape formation is performed.

  After the outer shape of the piezoelectric element plate 16 is formed as described above, the concave portion 14a that bears the vibration portion is formed to form an inverted mesa shape. The formation of the recess 14a may also be performed by wet etching. In addition, since the recess 14a in the form shown in FIG. 3 is etched only from one main surface, the side wall arranged parallel to the X ′ axis is along the crystal plane from the thick portion to the thin portion. An inclined surface will be formed.

  After the piezoelectric element plate 16 having an inverted mesa structure is formed as described above, electrode patterns such as the excitation electrode 18, the support electrode 22, and the conduction electrode 20 are formed. As an electrode pattern forming method, an electrode pattern material is formed on the entire piezoelectric element plate 16 by sputtering or vapor deposition, and then an unnecessary portion is etched using a resist or a mask, or a mask is previously formed on the surface of the piezoelectric element plate 16. A method of forming an electrode pattern material by sputtering or vapor deposition on the portion that is formed and exposed from the opening of the mask can be employed.

  According to the piezoelectric vibrating piece 10 having the above-described configuration, it is possible to suppress the stress generated due to fixing the support electrodes 22a and 22b from distorting the vibrating portion. Thereby, it can prevent that various frequency characteristics, such as an aging characteristic and a frequency temperature characteristic, deteriorate.

  In addition, by arranging the two support electrodes 22a and 22b as edges parallel to the X ′ axis, the proportion of the vibrating portion in the piezoelectric element plate 16 can be increased. Thereby, the effect of energy confinement is improved, and the coupling of the secondary vibration to the main vibration can be suppressed.

  Further, in the piezoelectric vibrating piece 10 shown in FIG. 3, the support electrode 22a connected to the excitation electrode 18a arranged on one main surface side is arranged on one main surface, and the excitation electrode 18b arranged on the other main surface is arranged on the excitation electrode 18b. The connected support electrode 22b is arranged on the other main surface, but as shown in FIG. 5, two support electrodes 22a and 22b may be arranged on the other main surface. In this case, the conductive electrode 20a may be routed using an edge portion formed parallel to the X ′ axis. Since the said edge part is comprised by convex shape, an acute angle part does not exist on the path | route which goes to the other main surface from one main surface. For this reason, it can avoid that the thickness of an electrode pattern becomes extremely thin in the transition part of each surface, and the disconnection of the conduction electrode 20a can be avoided. In addition, by disposing the two support electrodes 22a and 22b on the other main surface (the main surface opposite to the mounting surface), the conductivity used as a connection member when the piezoelectric vibrating reed 10 is mounted on a package or the like. The amount of adhesive can be reduced. Further, as the connecting member, it is possible to use a bump instead of the conductive adhesive. Thereby, it becomes possible to eliminate the conduction failure due to the configuration of the conductive adhesive.

  In addition, the oscillation frequency can be improved due to the inverted mesa type in which the vibrating part is thin. As a result, it is possible to excite vibrations in the high frequency band that the SAW resonator has conventionally been responsible for. Further, since the thick portion 12 is formed in a frame shape around the thin portion 14, the mechanical strength as the piezoelectric vibrating piece 10 can be ensured.

  Next, a piezoelectric device equipped with the piezoelectric vibrator having the above-described configuration will be described with reference to FIG. 6A is a front cross-sectional view showing the configuration of the piezoelectric device, and FIG. 6B is a plan view of the piezoelectric device with the lid removed.

  The piezoelectric device 50 according to the present embodiment is basically configured of the piezoelectric vibrating piece 10 and a package 56 that accommodates the piezoelectric vibrating piece 10. The package 56 includes a package base 52 having a cavity 62 that accommodates the piezoelectric vibrating piece 10, and a lid 54 that seals an opening of the package base 52.

  As described above, the package base 52 is a box having a cavity 62 for accommodating the piezoelectric vibrating piece 10. The constituent material is preferably an insulating material, and the manufacturing method may be a method of laminating a substrate such as a ceramic green sheet and sintering it.

  Inside the cavity 62 in the package base 52, an internal mounting terminal 58 for mounting the piezoelectric vibrating piece 10 is provided. An external mounting terminal 60 electrically connected to the internal mounting terminal 58 is provided on the outer bottom surface of the package base 52.

  The lid 54 is a lid that seals the upper opening of the package base 52 described above. The constituent material is preferably a member having a similar expansion coefficient to the package base 52. For example, when the package base 52 is made of a ceramic green sheet as described above, it is common to select Kovar, soda glass, or the like as the constituent material of the lid 54.

  The piezoelectric vibrating reed 10 is mounted on the package 56 having the above-described configuration through the conductive adhesive 64. As the conductive adhesive to be used, it is desirable to select an adhesive using an epoxy or polyimide hard resin as the binder. This is because the mounting state can be stabilized.

  Here, the piezoelectric vibrating reed 10 having the above-described configuration has a convex shape on the edge on which the support electrode 22a is disposed. Therefore, the conductive adhesive 64 has a good wraparound property and is not easily broken. This is because there is no place where the thickness of the conductive adhesive 64 that goes from the other surface to the one surface becomes extremely thin due to the absence of an acute angle portion in the cross section.

  Further, in the case of the piezoelectric device 50 on which the piezoelectric vibrating piece 10 having the above configuration is mounted, the stress propagated to the support electrodes 22a and 22b through the conductive adhesive 64 or the fixed support electrodes 22a and 22b. It is possible to suppress the influence of the thermal stress generated inside the piezoelectric vibrating piece due to the vibration portion on the vibrating portion. For this reason, deterioration of various characteristics such as aging characteristics and frequency temperature characteristics can be prevented.

  Next, a second embodiment according to the piezoelectric vibrating piece of the present invention will be described with reference to FIG. FIG. 7 shows a simplified form of the piezoelectric vibrating piece according to the present embodiment. 7A is a diagram illustrating a planar configuration of the piezoelectric vibrating piece, and FIG. 7B is a diagram illustrating a cross section taken along the line AA in FIG. 7A. () Is a figure which shows the BB cross section in the same figure (A). The basic configuration of the piezoelectric vibrating piece according to the present embodiment is the same as that of the piezoelectric vibrating piece according to the first embodiment described above. Therefore, portions having the same function are denoted by reference numerals added with 100 in the drawings, and detailed description thereof is omitted.

  The piezoelectric vibrating piece 110 according to the present embodiment is different from the piezoelectric vibrating piece 10 according to the first embodiment in that the support electrodes 122 (122a, 122b) are not arranged on the edge parallel to the X ′ axis. . That is, the piezoelectric vibrating piece 110 according to the present embodiment is formed between the edge formed in parallel to the X ′ axis and the recess 14a constituting the vibrating portion on a straight line parallel to the X ′ axis. The two support electrodes 122a and 122b are arranged in the thick portion 112. This is because, by arranging the support electrodes 122a and 122b in parallel with the X ′ axis, the area occupied by the vibration part can be sufficiently expanded even when the support electrodes 122a and 122b are not arranged on the edge.

  When the support electrode 122 is disposed on the inner surface of the piezoelectric vibrating piece 110 as in the present embodiment, the support electrode 122 is connected to the excitation electrode 118a disposed on any one surface (one main surface in the case illustrated in FIG. 7). The support electrode 122a is preferably formed by forming a via hole 123 in the piezoelectric base plate and dropping it into the other surface. This is because when the piezoelectric vibrating piece 110 is mounted on a package or the like, it is not necessary to wrap the conductive adhesive around the upper surface. In addition, it is desirable to use a method such as sand blasting or dry etching for forming the through holes constituting the via holes 123. Although through-holes can be formed also by wet etching, the etching rate differs due to the relationship between crystal directions, and it may be difficult to place the support electrodes 122a and 122b parallel to the X ′ axis. This is because sex occurs.

Next, a piezoelectric device including the piezoelectric vibrating piece according to the second embodiment will be described with reference to FIG.
The basic configuration of the piezoelectric device 50a according to the present embodiment is also the same as that of the piezoelectric device 50 shown in FIG. 6, and includes the piezoelectric vibrating piece 110 according to the embodiment and a package 56 that houses the piezoelectric vibrating piece 110. Is done.

  As a point different from the piezoelectric device 50 according to the above embodiment, a mounting form of the piezoelectric vibrating piece 110 can be cited. In the piezoelectric vibrating piece 110 according to the present embodiment, since the two support electrodes 122a and 122b are both arranged on the other main surface, the conductive adhesive used as the connecting member is used as one main surface. There is no need to wrap around the surface. For this reason, it becomes possible to use the bump 65 instead of the conductive adhesive as the connecting member.

  In the mounting using the bump 65, unlike the case where the conductive adhesive is used, there is a low possibility that a short circuit occurs due to the inflow of the connecting member. For this reason, the distance between the two support electrodes 122a and 122b can be reduced as compared with the case where a conductive adhesive is used as the connection member.

  Other configurations, operations, and effects are the same as those of the piezoelectric device 50 including the piezoelectric vibrating piece 10 according to the first embodiment described above.

  Next, a third embodiment according to the piezoelectric vibrating piece of the present invention will be described with reference to FIG. Since the basic configuration of the piezoelectric vibrating piece according to the present embodiment is the same as that of the piezoelectric vibrating piece 10 according to the first embodiment described above, FIG. 9 shows only the planar form of the piezoelectric vibrating piece. To do. Further, portions having the same configuration and function as those of the piezoelectric vibrating piece 10 according to the first embodiment are denoted by reference numerals obtained by adding 200 to the drawings, and detailed description thereof is omitted.

  In the piezoelectric vibrating piece 210 according to the present embodiment, one of the two support electrodes 222 (222a, 222b) (the support electrode 222a in the example shown in FIG. 9) is formed with an edge formed parallel to the X ′ axis. And the other support electrode (support electrode 222b in the example shown in FIG. 9) is an edge formed parallel to the X ′ axis. The first support electrode (support electrode 222a in the example shown in FIG. 9) is disposed at a position close to the first support electrode.

  Thickness-slip vibration, which is the main vibration of a piezoelectric vibrating piece using an AT-cut quartz element plate, is generated in an elliptical shape in the vibrating portion as indicated by a two-dot chain line in FIG. For this reason, the corner | angular part in the piezoelectric element board 216 formed in the rectangle becomes a part furthest from the generation | occurrence | production area | region of thickness shear vibration. Therefore, it is possible to reduce the influence of the stress generated between the support electrodes 222a and 222b on the vibration generation region.

  Other configurations, operations, and effects are the same as those of the piezoelectric vibrating piece 10 according to the first embodiment. The piezoelectric device on which the piezoelectric vibrating piece 210 according to this embodiment is mounted is the same as the piezoelectric device 50 on which the piezoelectric vibrating piece 10 according to the first embodiment is mounted.

  It has been described that the piezoelectric resonator element according to the above embodiment adopts an inverted mesa type in which a concave portion is formed on one main surface as a form of the piezoelectric element plate. However, the piezoelectric vibrating piece according to the present invention may be formed by forming concave portions on both main surfaces to form an inverted mesa type. Further, the piezoelectric vibrating piece according to the present invention has various types such as a flat plate, a mesa type, a bevel type, a plano bevel type, a convex type, a plano convex type, etc. It can take the form. Further, in the above-described embodiment, the planar form of the piezoelectric element plate is shown to be rectangular, but it may be a trapezoid or the like as long as it has at least a straight line parallel to the X ′ axis.

It is a figure which shows the plane structure of the piezoelectric vibrating piece which concerns on 1st Embodiment. It is a figure explaining the structure of an AT cut quartz base plate. It is a figure which shows the cross-sectional structure of the piezoelectric vibrating piece which concerns on 1st Embodiment. It is a graph which shows the relationship between the stress addition angle with respect to an AT cut quartz base plate, and a stress sensitivity ratio. It is sectional drawing which shows the deformation | transformation form of the piezoelectric vibrating piece which concerns on 1st Embodiment. It is a figure which shows the structure of the piezoelectric device which mounted the piezoelectric vibrating piece which concerns on 1st Embodiment. It is a figure which shows the structure of the piezoelectric vibrating piece which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the piezoelectric device which mounted the piezoelectric vibrating piece which concerns on 2nd Embodiment. It is a figure which shows the planar structure of the piezoelectric vibrating piece which concerns on 3rd Embodiment. It is a top view which shows the structure of a general AT cut piezoelectric vibrating piece. It is a top view which shows the structure of the conventional piezoelectric vibrating piece which aimed at relaxation of the influence of the stress with respect to a vibration part by the arrangement | positioning form of a support electrode.

Explanation of symbols

  10 ......... Piezoelectric vibrating piece, 12 ......... Thick part, 14 ......... Thin part, 14a ......... Recess, 16 ......... Piezoelectric element plate, 18 (18a, 18b) ......... Excitation electrode, 20 (20a, 20b) ..... Conduction electrode, 22 (22a, 22b) ..... Support electrode, 50 ..... Piezoelectric device, 52 .... Package base, 54 ..... Lid, 56 ..... Package, 58 ..... Internal mounting terminal, 60 .... External mounting terminal, 62 .... Cavity, 64 ..... Conductive adhesive, 65 .... Bump.

Claims (7)

An excitation electrode formed of an AT-cut quartz base plate and arranged in pairs on both main surfaces of the base plate, two support electrodes corresponding to each of the excitation electrodes, and the excitation electrode and the support electrode A piezoelectric vibrating piece provided with a conductive electrode for electrical connection,
The crystal axis X obtained by rotating the crystal axis X and the crystal axis Z ′ by 60 ° ± 10 ° or 120 ° ± 10 ° around the Y ′ axis with respect to the crystal axis Y ′ constituting the AT-cut quartz base plate 'And crystal axis Z "
An edge of the piezoelectric element plate is formed by two straight lines parallel to the crystal axis X ′ and a line intersecting the two straight lines,
A piezoelectric device characterized in that the support electrode is provided between a vibration part on a straight line parallel to the X ′ axis and where the excitation electrode is formed and an edge formed in parallel to the X ′ axis. Vibrating piece. The piezoelectric element plate comprises a thin part that constitutes the vibration part, and a thick part that surrounds the thin part,
The piezoelectric vibrating piece according to claim 1, wherein the support electrode is provided in the thick portion.   The piezoelectric vibrating piece according to claim 1, wherein the two support electrodes are arranged close to each other.   4. The piezoelectric vibrating piece according to claim 1, wherein the support electrode is disposed along an edge formed in parallel with the X′-axis. 5.   5. The piezoelectric vibrating piece according to claim 4, wherein one of the two support electrodes is disposed at a corner of the piezoelectric element plate, and the other is placed close to the corner.   6. A piezoelectric device comprising the piezoelectric vibrating piece according to claim 1 mounted in a package.   The piezoelectric device according to claim 6, wherein a bump is used when the piezoelectric vibrating piece is mounted in the package.

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