JP2011155551A - Piezoelectric device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device that is made more compact by making a piezoelectric vibration chip compact. <P>SOLUTION: A crystal vibrator 1 includes a crystal vibration chip 10 having a vibration portion 11 and a base 12, and a package 20 accommodating the crystal vibration chip 10. The crystal vibration chip 10 has a pair of lead electrodes 16a, 17a, led out of the vibration portion 11, formed on the base 12. The package 20 is provided with: an elastic resin projection 26, having a pair of conductive coating films 24, 25 formed on a surface, on a fixation surface 23 where the crystal vibration chip 10 is fixed; and an adhesive 30 is arranged at a periphery of the resin projection 26. In a state where the pair of conductive coating films 24, 25 are pressed against the pair of lead electrodes 16a, 17a through elastic deformation of the resin projection 26 and in a state that the both are electrically connected to each other, the crystal vibration chip 10 is fixed to the fixation surface 23 of the package 20 with the adhesive 30 interposed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piezoelectric device typified by a crystal resonator and the like, and an electronic apparatus including the piezoelectric device.

  Conventionally, a piezoelectric vibrator (hereinafter referred to as a piezoelectric vibrating piece) in which excitation electrodes are formed on both main surfaces of a rectangular piezoelectric substrate, and an extraction electrode connected to the excitation electrode is formed on the lower surface of one short side, There is known a piezoelectric device having a configuration in which a lead electrode and an electrode pad are connected via a conductive adhesive to a container (hereinafter referred to as a package) in which a pair of electrode pads is formed on the surface of a substrate. (For example, refer to Patent Document 1).

JP 2001-77656 A

With the progress of miniaturization, the piezoelectric device has a tendency that the distance between the lead electrodes of the piezoelectric vibrating piece and the distance between the electrode pads of the package are narrowed.
The conductive adhesive is usually a paste in which a metal filler such as Ag is mixed with an epoxy resin, silicone resin, polyimide resin or the like, and has fluidity so that it can be applied with a dispenser or the like. Have.
For these reasons, in the piezoelectric device, when the lead electrode of the piezoelectric vibrating piece and the electrode pad of the package are connected via the conductive adhesive, the conductive adhesive flows, and the lead electrodes of the piezoelectric vibrating piece are connected to each other. In addition, the electrode pads of the package may be short-circuited.

Accordingly, in order to avoid the above-described short circuit, the piezoelectric device needs to set the interval between the extraction electrodes of the piezoelectric vibrating piece and the interval between the electrode pads of the package to be equal to or larger than a predetermined interval.
As a result, the piezoelectric device has a problem in that further miniaturization cannot be achieved because the size of the piezoelectric vibrating piece is hindered by this restriction.

In addition, since the piezoelectric device needs to be connected with the interval between the extraction electrodes of the piezoelectric vibrating piece and the interval between the electrode pads of the package being set to a predetermined interval or more as described above, the ambient temperature change Due to the difference in expansion and contraction of the constituent elements, thermal stress of a certain level or more is generated in the piezoelectric vibrating piece.
Accordingly, the piezoelectric device has a problem that the temperature characteristics of the piezoelectric vibrating piece cannot be further improved due to the inhibition of vibration caused by thermal stress.

By the way, as a configuration for connecting the extraction electrode of the piezoelectric vibrating piece and the electrode pad of the package without using the conductive adhesive, for example, a configuration in which the connection is made through a metal bump is conceivable.
However, in the configuration using metal bumps, the connection is stronger than that of the conductive adhesive. For example, when an impact is applied from the outside, such as when dropped, the piezoelectric vibration remains without being shocked by the connection portion. There is a risk that the piezoelectric vibrating piece may be damaged by reaching the piece.

  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 A piezoelectric device according to this application example includes a piezoelectric vibrating piece having a vibrating portion and a base portion, and a package that accommodates the piezoelectric vibrating piece, and the piezoelectric vibrating piece is pulled out from the vibrating portion. The package has at least a pair of lead electrodes formed on the base, and the package has an elastic hemispherical resin projection on the fixing surface for fixing the piezoelectric vibrating piece and having at least a pair of conductive films formed on the surface. The at least one pair of conductive films is pressed against and electrically connected to the at least one pair of lead electrodes by elastic deformation of the resin protrusion.

According to this, in the piezoelectric device, the conductive film is pressed against the extraction electrode by the elastic deformation of the resin protrusion, and both are electrically connected.
As a result, the piezoelectric device has no fear of short-circuit in the electrical connection between the extraction electrode and the conductive coating (corresponding to the electrode pad) compared to the case where a conventional conductive adhesive is used. The interval between the extraction electrodes and the conductive film can be narrowed.
As a result, the piezoelectric device can be miniaturized because the piezoelectric vibrating piece can be miniaturized.

  Application Example 2 In the piezoelectric device according to the application example described above, an adhesive is disposed around the resin protrusion, and the piezoelectric vibrating piece is fixed to the fixing surface of the package via the adhesive. Preferably it is.

According to this, in the piezoelectric device, the conductive film is pressed against the extraction electrode by the elastic deformation of the resin protrusion, and the piezoelectric vibrating piece is disposed around the resin protrusion in a state where both are electrically connected. It is fixed to the package through the agent.
Therefore, in the piezoelectric device, the adhesive used for fixing the piezoelectric vibrating piece is arranged in the vicinity of the periphery of the resin protrusion, so that a predetermined interval is maintained using a conventional conductive adhesive. The thermal stress of the piezoelectric vibrating piece can be reduced as compared with the case where it is fixed (connected) at two locations.
Thereby, the piezoelectric device can improve the temperature characteristic of the piezoelectric vibrating piece.

In addition, since the piezoelectric vibrating piece is fixed through an adhesive, the piezoelectric device is sufficiently buffered by the adhesive when an impact is applied from the outside such as when dropped, and the piezoelectric vibrating piece is To reach.
Thereby, the piezoelectric device can reduce the damage of the piezoelectric vibrating piece at the time of impact compared with the case where the above-mentioned metal bump is used.

  Application Example 3 In the piezoelectric device according to Application Example 2, it is preferable that the adhesive has photosensitivity.

  According to this, since the adhesive of the piezoelectric device has photosensitivity, for example, the accuracy of the arrangement shape and position of the adhesive is compared with other adhesives using photolithography technology. And can be high.

  Application Example 4 An electronic apparatus according to this application example includes the piezoelectric device described in any one of Application Examples 1 to 3.

  According to this, since the electronic device includes the piezoelectric device described in any one of the application examples 1 to 3, the effect described in any one of the application examples 1 to 3 is achieved.

It is a schematic diagram which shows schematic structure of the crystal oscillator of 1st Embodiment, (a) is a top view seen from the lid side, (b), (c) is sectional drawing of (a). FIG. 6 is a schematic perspective view showing a main part of a crystal resonator according to a first modification. It is a schematic plan view which shows the principal part of the crystal oscillator of the modification 2, (a)-(c) shows the variation of the planar shape of an adhesive agent. The model perspective view which shows an example of the electronic device of 2nd Embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings.

Here, a crystal resonator will be described as an example of a piezoelectric device.
(First embodiment)
FIG. 1 is a schematic diagram illustrating a schematic configuration of the crystal resonator according to the first embodiment. FIG. 1A is a plan view seen from the lid (lid) side, FIG. 1B is a cross-sectional view taken along the line AA of FIG. 1A, and FIG. These are sectional drawings in the BB line of Drawing 1 (a). In the plan view, the lid is omitted for convenience. The sectional view is enlarged from the plan view.

As shown in FIG. 1, the crystal resonator 1 includes a crystal vibrating piece 10 as a piezoelectric vibrating piece and a package 20 that houses the crystal vibrating piece 10.
The quartz crystal vibrating piece 10 is an AT-cut type cut out from a quartz crystal at a predetermined angle, has a planar shape formed in a substantially rectangular shape, and includes a vibrating portion 11 and a base portion 12 connected to the vibrating portion 11. Yes.

In the quartz crystal resonator element 10, lead electrodes 16 a and 17 a drawn from excitation electrodes 16 and 17 formed on one main surface 14 and the other main surface 15 of the vibration portion 11 are formed on the base 12.
The extraction electrode 16 a is drawn from the excitation electrode 16 on one main surface 14 to the base 12 along the extending direction of the vibrating portion 11 (arrow C direction), and wraps around the other main surface 15 along the end surface of the base 12. The other main surface 15 extends to just before the excitation electrode 17.
The lead electrode 17a is drawn from the excitation electrode 17 on the other main surface 15 to the base portion 12 along the extending direction of the vibration portion 11, and wraps around the one main surface 14 along the end surface of the base portion 12, and the one main surface. It extends to the front of the 14 excitation electrodes 16.
The lead electrodes 16a and 17a are formed in the base 12 so as to be close to each other so as not to short-circuit each other.

The package 20 is formed in a substantially rectangular parallelepiped shape using a flat plate-like package base 21 having a substantially rectangular planar shape, a cap-shaped lid 22 covering the package base 21, and the like.
For the package base 21, an aluminum oxide sintered body formed by firing a ceramic green sheet is used.
For the lid 22, the same material as the package base 21, a metal such as Kovar, glass, or the like is used.

  The package base 21 is provided with a resin protrusion 26 having elasticity, on which a pair of conductive coatings 24 and 25 are formed on a fixed surface 23 for fixing the crystal vibrating piece 10. In addition, an adhesive 30 for fixing the crystal vibrating piece 10 to the fixing surface 23 is disposed around the resin protrusion 26.

The resin protrusion 26 is formed in a hemispherical shape. The conductive coatings 24 and 25 are formed on the surface of the resin protrusion 26 so as to face the extraction electrodes 16 a and 17 a when the base 12 of the quartz crystal vibrating piece 10 is placed on the resin protrusion 26.
More specifically, the conductive coating 24 extends to the surface of the fixed surface 23 in a direction (arrow D direction) where the tip portion faces the extraction electrode 16a and the other portion intersects the extension direction of the extraction electrode 16a. The conductive coating 25 is formed such that the tip portion faces the extraction electrode 17a and the other portion extends to the surface of the fixed surface 23 in the direction of arrow D.
In addition, the conductive coatings 24 and 25 are formed in a strip shape on a substantially straight line in a state where the tip portions are close to each other as much as the interval between the extraction electrodes 16a and 17a in a plan view.

The resin protrusion 26 is formed by coating an elastic resin material such as polyimide on the surface of the fixed surface 23 and performing a patterning process such as photolithography.
In addition to the polyimide resin, the resin protrusion 26 may be made of silicone-modified polyimide resin, epoxy resin, silicone-modified epoxy resin, acrylic resin, phenol resin, silicone resin, modified polyimide resin, benzocyclobutene, polybenzoxazole, or the like. A resin may be used.

The conductive coatings 24 and 25 formed on the surface of the resin protrusion 26 are vapor-deposited or sputtered with a conductive metal such as Au, TiW, Cu, Ni, Pd, Al, Cr, Ti, W, NiV, and lead-free solder. Is formed by applying an appropriate patterning process.
In addition, the conductive coatings 24 and 25 can further improve the conductive performance by further coating the surface of the underlying coating composed of Cu, Ni, Al or the like with Au plating or the like.

The adhesive 30 is formed on the surface of the fixed surface 23 in a substantially annular shape centering on the resin protrusion 26 by performing a patterning process such as photolithography, for example.
At this time, the adhesive 30 is formed avoiding the conductive coatings 24 and 25 so as not to overlap the conductive coatings 24 and 25 extending on the surface of the fixing surface 23. Thereby, the adhesive 30 becomes a substantially annular shape partially interrupted.
In addition, as the material for the adhesive 30, a resin having photosensitivity such as epoxy, polyimide, or acrylic is used. The adhesive 30 is cured by heating and pressing.

A pair of external terminals 28 and 29 used for mounting on an electronic device or the like are formed on the bottom surface (surface opposite to the fixed surface 23) 27 of the package base 21. The pair of external terminals 28 and 29 are made of a metal film in which a film such as Ni or Au is laminated on a metallized layer such as W by plating.
The pair of external terminals 28 and 29 are connected to the conductive coatings 24 and 25 by internal wiring (not shown). For example, the external terminal 28 is connected to the conductive coating 24, and the external terminal 29 is connected to the conductive coating 25.

In the crystal resonator 1, the base 12 of the crystal resonator element 10 is placed on the resin protrusion 26 and is fixed to the fixing surface 23 of the package base 21 by the adhesive 30.
At this time, in the quartz crystal resonator 1, the lead electrodes 16 a and 17 a formed on the base 12 of the crystal vibrating piece 10 and the conductive coatings 24 and 25 formed on the surface of the resin protrusion 26 are aligned with each other. In the state, the crystal vibrating piece 10 is pressed.
The quartz resonator 1 is electrically conductive by the reaction force of the resin protrusion 26 that is elastically deformed from the shape shown by the two-dot chain line in FIGS. 1B and 1C to the shape shown by the solid line. The crystal vibrating piece 10 is fixed to the fixing surface 23 of the package base 21 with the adhesive 30 in a state where the conductive films 24 and 25 are pressed against the extraction electrodes 16 a and 17 a and both are electrically connected.

In the crystal resonator 1, the package base 21 is covered with a lid 22 in a state where the crystal resonator element 10 is fixed to the fixing surface 23 of the package base 21, and the package base 21 and the lid 22 are not shown in the drawing. By bonding with a bonding member such as glass, the inside of the package 20 is hermetically sealed.
Note that the inside of the package 20 is in a vacuum state (high vacuum state) or in a state filled with an inert gas such as nitrogen, helium, or argon.

  In the crystal resonator 1, the crystal resonator element 10 is driven by a drive signal applied from outside through a pair of external terminals 28 and 29, conductive films 24 and 25, lead electrodes 16 a and 17 a, and excitation electrodes 16 and 17. Excited and resonates at a predetermined frequency.

As described above, in the crystal resonator 1 according to the first embodiment, the conductive coatings 24 and 25 are pressed against the extraction electrodes 16a and 17a by the elastic deformation of the resin protrusion 26, and both are electrically connected. The crystal vibrating piece 10 is fixed to the package base 21 via an adhesive 30 disposed around the resin protrusion 26.
As a result, the crystal resonator 1 is less likely to be short-circuited in the electrical connection between the extraction electrodes 16a and 17a and the conductive coatings 24 and 25 than when a conventional conductive adhesive is used. Therefore, the distance between the extraction electrodes 16a and 17a and the distance between the conductive films 24 and 25 can be narrowed.
As a result, the quartz crystal resonator 1 can be further downsized because the quartz crystal vibrating piece 10 can be downsized.

In addition, the quartz resonator 1 is arranged at a predetermined interval using a conventional conductive adhesive by disposing the adhesive 30 used for fixing the quartz vibrating piece 10 in the vicinity of the periphery of the resin protrusion 26. Compared with the case where it is held and fixed (connected) at two locations, the thermal stress of the crystal vibrating piece 10 can be reduced.
Thereby, the crystal unit 1 can improve the temperature characteristics of the crystal resonator element 10.

In addition, since the crystal resonator element 10 is fixed through the adhesive 30 in the crystal resonator 1, for example, when an impact is applied from the outside such as when dropped, the impact is sufficiently buffered by the adhesive 30. As a result, the crystal vibrating piece 10 is reached.
Thereby, compared with the case where the above-mentioned metal bump is used, the crystal unit 1 can reduce damage to the crystal vibrating piece 10 at the time of impact.
In addition, since the crystal resonator element 10 is fixed through the adhesive 30, the crystal resonator 1 can reduce vibration leakage as compared with the case where metal bumps are used.

In addition, since the adhesive 30 has photosensitivity, the quartz resonator 1 uses a photolithography technique to compare the accuracy of the arrangement shape, the arrangement position, and the like of the adhesive 30 with other adhesives. Can be expensive.
Further, in the quartz resonator 1, the adhesive 30 is formed in a substantially annular shape centering on the resin protrusion 26, and the distance from the resin protrusion 26 to the adhesive 30 is substantially equal in most directions. The accompanying distortion is easily equalized around the adhesive 30, and the inhibition of vibration due to adhesion can be suppressed.

In addition, since the crystal resonator 1 has a substantially annular shape with the adhesive 30 centered on the resin protrusion 26, patterning processing by photolithography or the like can be easily performed as compared with other shapes.
Note that the adhesive 30 may be disposed so as to overlap the portions of the conductive coatings 24 and 25 formed on the surface of the fixing surface 23.

Here, a modification of the first embodiment will be described.
(Modification 1)
FIG. 2 is a schematic perspective view showing the main part of the crystal resonator of the first modification. In addition, about a common part with 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted and it demonstrates centering on a different part from 1st Embodiment.
FIG. 2 shows the periphery of the resin protrusion before fixing the quartz crystal vibrating piece, and only the planar shape is indicated by a two-dot chain line for the sake of convenience for the portion of the adhesive on the front side of the paper surface.

As shown in FIG. 2, the crystal resonator 101 according to the first modification differs from the first embodiment in the shapes of the conductive coatings 124 and 125 formed on the surface of the resin protrusion 26.
The quartz crystal resonator 101 is formed in a semi-dome shape with a collar so that the conductive coatings 124 and 125 wrap the resin protrusions 26 in half.
According to this, since the area of the conductive coatings 124 and 125 is larger than that of the first embodiment, the crystal unit 101 can improve the strength of the conductive coatings 124 and 125. Thus, the electrical connection between the extraction electrodes 16a and 17a and the conductive coatings 124 and 125 can be more reliably performed.
In addition, the content of the modification 1 is applicable also to the following modifications.

(Modification 2)
FIG. 3 is a schematic plan view showing a main part of the crystal resonator of the second modification. In addition, about a common part with 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted and it demonstrates centering on a different part from 1st Embodiment.
FIG. 3 shows the periphery of the resin protrusion and the adhesive before fixing the crystal vibrating piece, and (a) to (c) show variations of the planar shape of the adhesive. In order to facilitate understanding, the adhesive portion is shaded.

As shown in FIG. 3, the crystal resonator 201 of Modification 2 is different from that of the first embodiment in the planar shape of the adhesive 230, and the planar shape of the adhesive 230 is (a) to (c). It has any one shape.
Specifically, in FIG. 3A, the planar shape of the adhesive 230 is a substantially rectangular frame shape, and in FIG. 3B, the planar shape of the adhesive 230 is a substantially rhombic frame shape. Yes.
Moreover, in FIG.3 (c), the planar shape of the adhesive agent 230 becomes a shape which deleted the corner part from the shape of Fig.3 (a). As a result, the shape of FIG. 3C has a smaller area of the adhesive 230 than the shape of FIG. 3A, and accordingly, the inhibition of the vibration of the quartz crystal resonator element 10 (see FIG. 1) due to adhesion is reduced. Can be suppressed.
Note that the planar shape of the adhesive 230 is not limited to the above-described shape, and may be appropriately set within a range that does not hinder the fixation of the crystal vibrating piece 10 such as an elliptical shape or a polygonal shape.

(Second Embodiment)
FIG. 4 is a schematic perspective view illustrating an example of an electronic apparatus including the crystal resonator described in the first embodiment and each modification of the second embodiment.
A mobile phone 300 shown in FIG. 4 includes the above-described crystal resonator (such as 1) as a reference clock oscillation source and the like, and further includes a liquid crystal display device 301, a plurality of operation buttons 302, an earpiece 303, and a mouthpiece 304. Configured.

  The above-described crystal resonators (1 and the like) are not limited to the above-described mobile phones, but include electronic books, personal computers, digital still cameras, liquid crystal televisions, viewfinder type or monitor direct-view type video tape recorders, car navigation devices, pagers, electronic It can be suitably used as a reference clock oscillation source for devices such as notebooks, calculators, word processors, workstations, videophones, POS terminals, touch panels, etc. In any case, the first embodiment and each modification It is possible to provide an electronic device that exhibits the effects described above.

In the above embodiments and modifications, the extraction electrodes 16a and 17a and the conductive coating (24, 25, etc.) of the quartz crystal vibrating piece 10 have been described as a pair. However, the present invention is not limited to this, and a plurality of pairs But you can.
Moreover, in each said embodiment and each modification, although the resin protrusion 26 is formed in the hemispherical shape, you may be formed in the substantially hemispherical shape.

  In each of the above-described embodiments and modifications, the quartz resonator is described as an example of the piezoelectric device. However, the present invention is not limited to this, and various devices such as a quartz oscillator, a frequency filter, a gyro sensor, and a pressure sensor are used. It can also be applied to sensors.

In each of the above-described embodiments and modifications, the AT-cut type is used as the crystal vibrating piece. However, the present invention is not limited to this, and a tuning fork type, a SAW element type, a WT type (for gyro element) or the like is used. Also good.
In addition, the material of the piezoelectric vibrating piece is not limited to quartz. For example, lithium tantalate (LiTaO ₃ ), lithium tetraborate (Li ₂ B ₄ O ₇ ), lithium niobate (LiNbO ₃ ), titanium A piezoelectric body such as lead zirconate (PZT), zinc oxide (ZnO), or aluminum nitride (AlN) may be used. Further, a semiconductor such as silicon formed on a surface of a piezoelectric body such as zinc oxide (ZnO) or aluminum nitride (AlN) may be used.

  DESCRIPTION OF SYMBOLS 1 ... Crystal resonator as a piezoelectric device, 10 ... Quartz vibrating piece as a piezoelectric vibrating piece, 11 ... Vibrating part, 12 ... Base, 14 ... One main surface, 15 ... Other main surface, 16 ... Excitation electrode, 16a DESCRIPTION OF SYMBOLS ... Extraction electrode, 17 ... Excitation electrode, 17a ... Extraction electrode, 20 ... Package, 21 ... Package base, 22 ... Lid, 23 ... Fixed surface, 24, 25 ... Conductive film, 26 ... Resin protrusion, 27 ... Bottom surface, 28 , 29 ... external terminals, 30 ... adhesive, 101 ... crystal resonator, 124, 125 ... conductive coating, 201 ... crystal resonator, 230 ... adhesive, 300 ... mobile phone as an electronic device, 301 ... liquid crystal display device , 302 ... operation buttons, 303 ... earpiece, 304 ... mouthpiece.

Claims (4)

A piezoelectric vibrating piece having a vibrating part and a base part;
A package containing the piezoelectric vibrating piece,
In the piezoelectric vibrating piece, at least a pair of extraction electrodes extracted from the vibration unit is formed on the base,
The package is provided with a hemispherical resin protrusion having elasticity with at least a pair of conductive films formed on a surface of the fixed surface for fixing the piezoelectric vibrating piece,
The piezoelectric device, wherein the at least one pair of conductive films is pressed and electrically connected to the at least one pair of lead electrodes by elastic deformation of the resin protrusion.   The piezoelectric device according to claim 1, wherein an adhesive is disposed around the resin protrusion, and the piezoelectric vibrating piece is fixed to the fixing surface of the package via the adhesive. Piezoelectric device.   The piezoelectric device according to claim 2, wherein the adhesive has photosensitivity.   An electronic apparatus comprising the piezoelectric device according to claim 1.

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