JP2013102487A - Piezoelectric vibration piece, piezoelectric device and manufacturing method of piezoelectric vibration piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibration piece which prevents disconnection of electrode patterns conductive with excitation electrodes, and further to provide a piezoelectric device and a manufacturing method of the piezoelectric vibration piece.SOLUTION: In a piezoelectric vibration piece, electrode patterns 32 conductive with excitation electrodes 30 are provided at a base end 18 side for supporting a piezoelectric element plate 12 in a cantilever manner while the excitation electrodes 30 are being provided on principal surfaces 12a and 12b of the piezoelectric element plate 12. Further, in the piezoelectric vibration piece, the electrode patterns 32 are led out on portions 22 gradually becoming thinner from inside toward outside where angles between the one principal surface 12a and a lateral surface 12c and between one principal surface 12b and the lateral surface 12c of the piezoelectric element plate 12 become obtuse angles due to wet etching when an outer shape of the piezoelectric element plate 12 is formed.

Description

  The present invention relates to a piezoelectric vibrating piece, a piezoelectric device, and a method for manufacturing a piezoelectric vibrating piece.

The piezoelectric vibrating piece forms a plurality of piezoelectric vibrating pieces from a single piezoelectric wafer. In the invention described in Patent Document 1, a plurality of crystal pieces are obtained from a crystal substrate such as an AT cut. Specifically, in order to obtain this crystal piece, a metal film is first formed on a crystal substrate, and then a photoresist pattern following the external pattern such as a piezoelectric vibrating piece is provided on the metal film. Then, after etching the metal film using the photoresist pattern as a protective film, the crystal substrate is etched using the photoresist pattern and the metal film pattern as a protective film to form a crystal piece, an arm portion, and a frame portion. The base end side of the crystal piece is in the −X direction, and is fixed to the frame portion via the arm portion. The tip side of the crystal piece is in the + X direction. Thereafter, the photoresist pattern and the metal film are peeled off, and an electrode is formed on the crystal piece to obtain a crystal piece aggregate. Next, the crystal piece is separated into pieces by folding the crystal piece from the arm portion.
The quartz crystal resonator element described in Patent Document 2 is held at one end, and the −X side is a free end and the + X side is a fixed end.

Japanese Patent Laying-Open No. 2006-186847 (page 6, FIGS. 1 and 2) JP 2005-130218 A (paragraph 0023)

  As described above, before the crystal piece described in Patent Document 1 is folded from the frame, the base end side of the crystal piece in the −X direction is fixed to the frame portion, and the + X direction is the front end side. In such a crystal piece, when the outer shape of the crystal piece is formed, the corner portion on the tip side is etched, and a large penetration into the inside of the chip occurs. That is, the tip end side of the crystal piece gradually becomes thinner from the inside to the outside of the chip.

  By the way, in a crystal resonator or the like having a crystal piece mounted on a package, it is necessary to prevent the crystal piece from being bent even when an impact is applied due to dropping or the like. For this reason, a pillow is provided on the bottom surface inside the package so as to support the tip side of the crystal piece to prevent the crystal piece from being bent. However, as described above, when a crystal piece with an intrusion is supported by a “pillow”, the crystal piece is thin, so that it is weak against shocks. The piece may be damaged. Therefore, the reliability (impact resistance) of the device on which the crystal piece is mounted is deteriorated.

  An excitation electrode is formed on the main surface of the crystal piece. However, when the penetration becomes large, it reaches the portion where the excitation electrode is formed, and the shape influence is generated on the excitation electrode. Further, when the crystal piece is a mesa shape, the shape effect of the thick mesa portion is generated. Therefore, in these cases, the vibration region of the crystal piece is hindered, and various characteristics of the crystal piece are deteriorated.

Furthermore, although the base end of the crystal piece described in Patent Document 1 is connected to the arm portion, the shape near the support portion is complicated by etching. When such a crystal piece is folded from the arm portion, a large amount of broken scraps are generated, and a large residue (burr) is generated at the time of folding. When a crystal piece with a large residue is mounted on the package, the package comes into contact with the conductive wall surface of the package, causing a problem that the crystal piece does not oscillate.
Patent Document 2 does not describe how to draw an electrode pattern around a crystal piece.

  An object of the present invention is to provide a piezoelectric vibrating piece, a piezoelectric device, and a method of manufacturing the piezoelectric vibrating piece that prevent disconnection of an electrode pattern that is electrically connected to an excitation electrode.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1] An excitation electrode is provided on the main surface of the piezoelectric element plate, and an electrode pattern connected to the excitation electrode is provided on the base end side that cantilever-supports the piezoelectric element plate, thereby forming the outer shape of the piezoelectric element plate. The piezoelectric material is characterized in that an intrusion in which an angle formed between one main surface and a side surface of the piezoelectric element plate is an obtuse angle is formed by wet etching, and the electrode pattern is drawn around the intrusion. Vibrating piece.
Thus, since the electrode pattern is provided in the obtuse angle part, disconnection of the electrode pattern can be prevented. In addition, since the piezoelectric vibrating piece is provided with the electrode pattern in the portion where the penetration occurs, the excitation electrode is provided in the portion where the penetration does not occur. For this reason, it is possible to prevent the shape of the piezoelectric element plate where the excitation electrode is provided from being deformed by etching, and thus it is possible to prevent the shape of the excitation electrode from being changed. Further, since no penetration occurs in the portion where the excitation electrode is provided, the rigidity of the piezoelectric vibrating piece can be improved.

Application Example 2 The piezoelectric element plate is an AT-cut quartz element plate, a direction connecting the base end and the tip end of the piezoelectric element plate is along the X axis of the crystal axis of the crystal, and the base end is The piezoelectric vibrating piece according to Application Example 1, wherein the piezoelectric vibrating piece is located on the + X side of the tip.
As a result, the penetration is formed on the + X side in the side along the X axis, so that the excitation electrode can be provided on the −X side and the electrode pattern on the + X side. Therefore, it is possible to prevent the shape of the tip side of the piezoelectric element plate from being deformed by etching.

Application Example 3 A connection portion connected to a support portion is provided on a side on the base end side that cantilever-supports the piezoelectric element plate, and the connection portion connected to the base end of the piezoelectric vibrating piece is formed by wet etching. 3. The piezoelectric vibrating piece according to Application Example 1 or 2, wherein a narrowing penetration is provided.
Since the base end side of the piezoelectric element plate can be thinned by etching, the cross-sectional area of the portion where the piezoelectric element plate is folded from the piezoelectric wafer can be reduced. Therefore, it can be folded only by applying a weak force to the piezoelectric element plate, and can be broken at an intended location, so that it is possible to prevent breakage and generation of a residue.

Application Example 4 A piezoelectric device comprising the piezoelectric vibrating piece according to any one of Application Examples 1 to 3 mounted in a package.
Since the piezoelectric device has the mesa-type piezoelectric vibrating piece having the above-described features, the mesa-type piezoelectric vibrating piece can be put into the recessed portion, and the wall surface of the package and the conductive adhesive come into contact with each other. Can be prevented. Furthermore, even when an impact due to dropping or the like is applied to the piezoelectric device, it is possible to prevent the piezoelectric vibrating piece from being damaged on the tip side of the piezoelectric vibrating piece. Therefore, the reliability (impact resistance) of the piezoelectric device can be improved.

[Application Example 5] The piezoelectric device according to Application Example 4, wherein a conductive adhesive is provided on the electrode pattern that has been routed into the entrance, and the piezoelectric vibrating reed is electrically connected to the package side.
Thereby, conduction between the conductive adhesive and the excitation electrode can be ensured.

Application Example 6 Wet etching of an AT-cut quartz wafer, a piezoelectric vibrating piece having the + X side of the quartz crystal axis as a leading end and a -X side as a base end, the base end of the piezoelectric vibrating piece, and the crystal wafer main body A connecting portion that connects the piezoelectric vibrating piece and the connecting portion is formed by wet etching to narrow the connecting portion, and the piezoelectric vibrating piece is folded from the place where the penetration occurs. A method of manufacturing a piezoelectric vibrating piece, wherein the piezoelectric vibrating piece is cut into pieces.
The portion where the penetration is formed is thinner than the thickness of the AT-cut quartz wafer. For this reason, it is possible to easily break the piezoelectric vibrating piece from the crystal wafer main body, and to reduce the occurrence of breakage.

It is explanatory drawing of a piezoelectric vibrating piece. It is the schematic plan view which expanded a part of piezoelectric wafer which formed the mesa type piezoelectric vibrating piece. It is explanatory drawing of the part which the mesa type piezoelectric vibrating piece and the connection part are connected. It is explanatory drawing of a mesa type piezoelectric device.

  Hereinafter, the best embodiments of the piezoelectric vibrating piece, the piezoelectric device, and the method of manufacturing the piezoelectric vibrating piece according to the present invention will be described. In the following, a mode using a mesa-type piezoelectric vibrating piece as an example of the piezoelectric vibrating piece will be described, but the present invention is not limited to this mode. That is, the piezoelectric vibrating piece according to the present invention may have a shape other than the mesa shape, for example, a flat plate shape.

  First, the mesa type piezoelectric vibrating piece will be described. FIG. 1 is an explanatory diagram of a piezoelectric vibrating piece. Here, FIG. 1A is a plan view of a mesa-type piezoelectric vibrating piece, and FIG. 1B is a cross-sectional view taken along the line AA of FIG. The mesa-type piezoelectric vibrating piece 10 has a piezoelectric element plate 12. The piezoelectric element plate 12 has a thick portion 14 and a thin portion 16 formed thinner than the thick portion 14. The thin portion 16 is adjacent to the thick portion 14 and is provided at the center of the thick portion 14 in the height direction. As a specific example of the piezoelectric element plate 12, an AT-cut crystal element plate can be cited. As shown in FIG. 1A, the mesa-type piezoelectric vibrating piece 10 using this AT-cut quartz base plate has a long side along the X axis and a short side along the ZZ ′ axis. The base end 18 side of the mesa-type piezoelectric vibrating piece 10 is the + X side, and the tip 20 side is the −X side.

  For this reason, if the piezoelectric element plate 12 is wet-etched when forming the outer shape pattern thereof, the side surface 12c on the base end 18 side in the long side is etched to form the intrusion 22. As shown in FIG. 1B, the intrusion 22 is formed on the + ZZ ′ side by etching the upper main surface 12a of the two long sides formed on the −ZZ ′ side. The thing has etched the lower main surface 12b side. The angle formed between the upper main surface 12a and the -ZZ 'side entry 22 is an obtuse angle, and the angle formed between the lower main surface 12b and the + ZZ' side entry 22 is an obtuse angle.

  In such a piezoelectric base plate 12, excitation electrodes 30 are provided on the main surface of the thick portion 14. Electrode patterns 32 (mount electrodes 34) are provided at both corners on the base end 18 side of the piezoelectric element plate 12, respectively. The mount electrode 34 is electrically connected to the excitation electrode 30 by a lead electrode 36 (electrode pattern 32). The mount electrode 34 is provided on the upper main surface 12a, the lower main surface 12b, and the side surface 12c of the piezoelectric base plate 12 (thin portion 16). As a result, the mount electrode 34 provided on the upper main surface 12a and the mount electrode 34 provided on the lower main surface 12b are electrically connected via the side surface 12c. The mount electrode 34 is also provided on the surface of the entrance 22. As a result, the mount electrode 34 is less likely to be disconnected at a location where the angle formed between the main surfaces 12a and 12b of the piezoelectric base plate 12 (thin portion 16) and the entry 22 is an obtuse angle.

  An example of a method for manufacturing the mesa type piezoelectric vibrating piece 10 is as follows. FIG. 2 is an enlarged schematic plan view of a part of the piezoelectric wafer on which the mesa piezoelectric vibrating piece is formed. FIG. 3 is an explanatory diagram of a portion where the mesa-type piezoelectric vibrating piece and the connecting portion are connected. 3A is a plan view, FIG. 3B is a cross-sectional view taken along the broken line BB ′ in FIG. 3A, and FIG. 3C is taken along the broken line CC ′ in FIG. It is sectional drawing.

  First, the piezoelectric base plate 12, that is, the thick portion 14 and the thin portion 16 provided around the thick portion 14 can be formed by processing using photolithography and etching. The specific formation process of the piezoelectric element plate 12 is as follows. First, a mask made of a metal film is formed on the surface of the piezoelectric wafer 40, and then the piezoelectric wafer 40 exposed in the opening of the mask is wet-etched to form a plurality of piezoelectric element plates from the piezoelectric element plate 12 and one piezoelectric wafer 40. 12 are formed, such as a support portion 42 formed to obtain 12, a connection portion 44 that connects the support portion 42 and the piezoelectric element plate 12, and a frame portion 46 that connects the plurality of support portions 42. The support portion 42 and the frame portion 46 serve as a piezoelectric wafer body. If the piezoelectric wafer is an AT-cut quartz wafer, the support portion 42 and the frame portion 46 are the quartz wafer body. Further, if the piezoelectric wafer is an AT-cut quartz wafer, as shown in FIG. 2, the base end 18 side of the piezoelectric base plate 12 is in the + X direction of the crystal crystal axis, and the tip 20 side is in the −X direction. Is along the ZZ ′ axis of the quartz crystal axis.

  Next, in order to form the thick portion 14, a portion corresponding to the portion where the thick portion 14 is formed is covered with a metal film mask, and the opening portion of the mask is wet-etched. As a result, the thin portion 16 is formed on the piezoelectric base plate 12, and when the metal film serving as the mask is removed, the piezoelectric wafer 40 becomes a shape as shown in FIG. The base plate 12 can be obtained. In FIG. 2, descriptions of the thick portion 14, the cutout portion 48, the entry 22, and the like are omitted.

In the obtained piezoelectric wafer 40, a notch portion 48 is provided between the piezoelectric element plate 12 and the connecting portion 44 in order to make it easy to fold the mesa-type piezoelectric vibrating piece 10 from the piezoelectric wafer 40 (FIG. 3). See). As shown in FIG. 3A, the notch 48 is provided at a location where the long side of the piezoelectric element plate 12 and the side along the X axis of the connecting part 44 are connected, and the piezoelectric element plate. 12 is cut out from an upper main surface 12a to a lower main surface 12b. Further, as shown in FIGS. 3B and 3C, a groove 50 is formed between the piezoelectric element plate 12 and the connecting portion 44 along the short side direction of the piezoelectric element plate 12. Is integrally connected to the connecting portion 44 on the lower main surface 12b side. The groove 50 is an intrusion formed by wet etching. For this reason, the connecting portion 44 connected to the base end 18 of the mesa-type piezoelectric vibrating piece 10 is thinner than the piezoelectric wafer body.
Further, as shown in FIG. 3A, an intrusion 22 is formed on the main surface 12 b below the piezoelectric element plate 12. By providing such a notch 48, the mesa piezoelectric vibrating piece 10 can be easily folded from the piezoelectric wafer 40.

After the piezoelectric element plate 12 is formed on the piezoelectric wafer 40, the excitation electrode 30, the mount electrode 34, and the extraction electrode 36 are formed on the surface of the piezoelectric element plate 12. These electrodes 30, 34, and 36 may be obtained by forming a metal film for electrodes having a pattern following the electrode shape on the surface of the piezoelectric element plate 12. In this case, since a metal film for an electrode is also formed on the surface of the entrance 22 of the piezoelectric base plate 12, the electrode pattern 32 at a location where the angle formed by the main surfaces 12a, 12b and the entrance 22 is an obtuse angle. The disconnection is prevented. Thereby, the mesa-type piezoelectric vibrating piece 10 connected to the piezoelectric wafer 40 is formed.
Thereafter, when the mesa-type piezoelectric vibrating piece 10 is folded from the connecting portion 44, the mesa-type piezoelectric vibrating piece 10 separated into pieces is obtained as shown in FIG. Note that the mesa-type piezoelectric vibrating piece 10 is broken off at the intrusion (groove 50) portion formed in the connecting portion 44.

  According to such a mesa type piezoelectric vibrating piece 10, since the electrode pattern 32 is provided also in the intrusion 22 where the angle between the main surfaces 12a and 12b is an obtuse angle, disconnection of the electrode pattern 32 can be prevented.

  Further, since the mesa-type piezoelectric vibrating piece 10 is provided with the mount electrode 34 on the base end 18 side where the intrusion 22 occurs due to etching, the intrusion 22 does not occur on the distal end 20 side of the piezoelectric base plate 12. For this reason, since the shape of the tip 20 side can be prevented from being deformed by etching, the shape of the thick portion 14 can also be prevented from being deformed. As a result, the rigidity of the mesa-type piezoelectric vibrating piece 10 can be improved and the shape of the thick portion 14 and the excitation electrode 30 can be prevented from changing. The vibration region can be secured even when the plane size of the piezoelectric element 12 is reduced.

  Further, since the shape of the portion where the mesa-type piezoelectric vibrating piece 10 and the connecting portion 44 are connected (the shape of the portion to be broken at the time of folding) is a simple shape as shown in FIG. 3, the mesa-type piezoelectric vibration The piece 10 can be easily broken off from the connecting portion 44. That is, since the base end 18 side of the piezoelectric element plate 12 is thinned by etching, the cross-sectional area of the portion to be folded can be reduced. As a result, a strong force is applied when folding, and breakage from an unintended place can be prevented. Further, since generation of breakage debris during folding can be prevented, it is possible to prevent breakage debris from being attached to the vibration region, increasing the crystal impedance value and degrading the Q value. Furthermore, since the generation of a residue (burr) at the time of breaking can be prevented, the residue can be prevented from coming into contact with the wall surface when the mesa piezoelectric vibrating piece 10 is mounted on a package.

  Next, a piezoelectric device (mesa type piezoelectric device) on which the above-described mesa type piezoelectric vibrating piece 10 is mounted will be described. FIG. 4 is an explanatory diagram of a mesa piezoelectric device. In FIG. 4, the description of the excitation electrode 30 and the electrode pattern 32 is omitted. The mesa piezoelectric device 60 includes the package 62. The package 62 has a package base 64 and a lid 72. The package base 64 includes a recessed portion 66 that opens upward, and a pair of package-side mount electrodes 68 are provided on the bottom surface of the recessed portion 66. An external terminal 70 is provided on the back surface of the package base 64 and is electrically connected to the package-side mount electrode 68 on a one-to-one basis.

  The package base 64 may have a configuration in which a recess 66 is formed by disposing a frame-type seam ring on the upper surface of a flat insulating sheet. In this case, the package-side mount electrode 68 may be provided on the upper surface of the insulating sheet, and the external terminal 70 may be provided on the lower surface. As a result, the side wall of the package base 64 is formed by a seam ring. Therefore, the lid 72 can be directly joined onto the seam ring, and the package 62 can be made thin.

A conductive adhesive 74 is applied on the package side mount electrode 68, and the mesa piezoelectric vibrating piece 10 is disposed on the conductive adhesive 74. At this time, the conductive adhesive 74 is bonded to the mount electrode 34, and in the mesa-type piezoelectric vibrating piece 10 having the configuration shown in FIG. As a result, the intrusion 22 has an obtuse angle with the upper principal surface 12a of the piezoelectric element 12 (thin portion 16) (an indentation 22 formed on the −ZZ ′ side of the long side of the piezoelectric element 12). Since the conductive adhesive 74 also comes into contact, the package-side mount electrode 68 and the excitation electrode 30 of the mesa-type piezoelectric vibrating piece 10 are reliably conducted one-to-one via the conductive adhesive 74.
Thus, the lid 72 is joined to the upper surface of the package base 64 on which the mesa-type piezoelectric vibrating piece 10 is mounted, and the recessed portion 66 is hermetically sealed.

  According to such a mesa type piezoelectric device 60, the mesa type piezoelectric vibrating piece 10 in which the generation of the etching residue is suppressed is mounted, so that the mesa type piezoelectric vibrating piece 10 and the side wall of the package 62 are in contact with each other. Is preventing. Here, if there is a residue on the mesa-type piezoelectric vibrating piece, the residue may cause the conductive adhesive to come into contact with the wall surface of the recessed portion, resulting in a defective product. Further, if the residue is long, the mesa type piezoelectric vibrating piece cannot be put into the recessed portion. On the other hand, since the mesa piezoelectric vibrating piece 10 according to the present embodiment has no residue, the mesa piezoelectric vibrating piece 10 can be put into the recessed portion 66, and the conductive adhesive 74 and the wall surface of the recessed portion 66 can be used. Can be prevented from contacting and conducting.

  Further, since the mesa-type piezoelectric vibrating piece 10 does not enter the tip 20 side, the penetration 22 does not occur when the mesa-type piezoelectric vibrating piece 10 is cantilever-mounted on the package 62. . For this reason, even if the mesa piezoelectric device 60 falls and has an impact, it is possible to prevent the mesa piezoelectric vibrating piece 10 from being damaged. Therefore, the reliability (impact resistance) of the mesa piezoelectric device 60 can be improved.

  The mesa piezoelectric device 60 is not only in the form of a mesa piezoelectric vibrator as shown in FIG. 4 but also in the form of a mesa piezoelectric oscillator in which an oscillation circuit is housed in a package 62 together with the mesa piezoelectric vibrating piece 10. You can also.

  DESCRIPTION OF SYMBOLS 10 ......... Mesa type piezoelectric vibrating piece, 12 ......... Piezoelectric element plate, 12a ......... Upper main surface, 12b ......... Lower main surface, 12c ......... Side, 14 ......... Thick part, 16 ......... Thin part, 18 ......... Base end, 20 ......... Tip, 22 ...... Intrusion, 30 ......... Excitation electrode, 32 ......... Electrode pattern, 40 ......... Piezoelectric wafer, 42 ... ... support part, 44 ... connection part, 48 ... notch, 60 ... mesa piezoelectric device, 62 ... package, 74 ... conductive adhesive.

Claims (6)

An excitation electrode is provided on the main surface of the piezoelectric element plate, and an electrode pattern connected to the excitation electrode is provided on the base end side that cantilever-supports the piezoelectric element plate,
By wet etching when forming the outer shape of the piezoelectric element plate, forming an indentation in which the angle between one main surface and the side surface of the piezoelectric element plate is an obtuse angle,
The electrode pattern was routed around the penetration,
A piezoelectric vibrating piece characterized by that. The piezoelectric element plate is an AT cut crystal element plate,
The direction connecting the base end and the tip of the piezoelectric element plate is along the X axis of the crystal axis of the crystal, and the base end is on the + X side from the tip.
The piezoelectric vibrating piece according to claim 1.   A connecting portion connected to a supporting portion is provided on the side of the base end side that cantilever-supports the piezoelectric element plate, and an intrusion that narrows the connecting portion at a location connected to the base end of the piezoelectric vibrating piece by the wet etching is provided. The piezoelectric vibrating piece according to claim 1, wherein the piezoelectric vibrating piece is provided.   A piezoelectric device comprising the piezoelectric vibrating piece according to claim 1 mounted on a package.   5. The piezoelectric device according to claim 4, wherein a conductive adhesive is provided on the electrode pattern that has been drawn around to make the piezoelectric vibrating piece conductive to the package side. A wet-etching of the AT-cut quartz wafer, a piezoelectric vibrating piece having a + X side of the quartz crystal axis as a tip and a -X side as a base, and a connecting portion that connects the base end of the piezoelectric vibrating piece and the crystal wafer body; And forming an intrusion that narrows the connecting portion between the piezoelectric vibrating piece and the connecting portion by the wet etching,
Folding the piezoelectric vibrating piece from the place where the intrusion occurred, and dividing it into pieces,
A method of manufacturing a piezoelectric vibrating piece.

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