JP4569830B2 - Bonding structure of piezoelectric vibrating piece and piezoelectric device - Google Patents

Description

  The present invention relates to a piezoelectric vibrating piece joining structure having a fixing arm for joining a piezoelectric vibrating piece to a package, and a piezoelectric device, separately from a base portion that supports the vibrating arm.

Piezoelectric devices are widely used in small information devices such as HDDs (hard disk drives), mobile computers, and IC cards, and mobile communication devices such as mobile phones, car phones, and paging systems.
FIG. 5 is a schematic plan view of the conventional piezoelectric device 1, and FIG. 6 is a cross-sectional view taken along line AA of FIG. 5 (see, for example, Patent Document 1).
In these drawings, the piezoelectric device 1 shows an example of a piezoelectric vibrator, and a piezoelectric vibrating piece 3 is accommodated in a package 2.

The piezoelectric vibrating reed 3 includes a pair of vibrating arms 5 and 5 extending in parallel to each other and a base 4 that supports the vibrating arms 5 and 5.
Fixing arms 6 and 6 extending in parallel with the vibrating arms 5 and 5 are integrally formed from the base 4, and a balance portion 7 is integrally formed in a direction opposite to the vibrating arms 5 and 5. Yes.
Then, the fixing arms 6 and 6 are bonded to the mount electrodes 12 and 12 on the package 2 side on the virtual line GP1 in the width direction passing through the center of gravity GP of the piezoelectric vibrating piece 2 by applying adhesives 10 and 10. Yes.

  Thereby, with respect to the longitudinal direction of the piezoelectric vibrating piece 3, both end portions are balanced with respect to the virtual line GP1 to prevent the vibration of the piezoelectric vibrating piece 3 in the thickness direction (arrow direction in FIG. 6). Therefore, it is possible to prevent chipping and cracking that occur when both ends of the piezoelectric vibrating reed 3 come into contact with the inner bottom surface 2 a of the package 2.

Japanese Patent Application Laid-Open No. 2004-297198

  However, when the piezoelectric vibrating piece 3 is joined to the package 2 by applying the adhesive 10 on the imaginary line GP1 in the width direction passing through the center of gravity GP like the piezoelectric device 1, when the shock is applied from the outside, FIG. As shown in FIG. 6, the adhesive 10 at the position of the virtual line GP1 becomes a fulcrum, and the piezoelectric vibrating reed 3 may swing in the thickness direction.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric vibrating piece joining structure and a piezoelectric device that effectively prevent vibrations in the thickness direction of the piezoelectric vibrating piece and have excellent vibration characteristics.

According to the first aspect of the present invention, the tuning fork-type piezoelectric vibrating piece having a base for supporting two vibrating arms having long grooves branches in a longitudinal direction of the vibrating arm and extends from the base. A plurality of fixing arms formed so as to extend along the piezoelectric member, and bonded to the package with an adhesive, wherein the plurality of fixing arms are bonded to the package, respectively. 1st and 2nd joining location is provided in order close to the base, and the 2nd adhesion used for joining of the 2nd joining location rather than the 1st adhesive used for joining of the 1st joining location The agent is harder and is a conductive adhesive, the first adhesive is a non-conductive adhesive, and the second joining portion is disposed closer to the base than the distal end of the long groove. the bonding structure of the piezoelectric vibrating piece being It is made.

According to the configuration of the first invention, the plurality of fixing arms formed so as to extend along the longitudinal direction of the vibrating arm are provided in the order in which the first and second joining portions joined to the package are closer to the base. since being, joint is without such that the fulcrum is suppressed oscillation of thickness direction of the piezoelectric vibrating piece.
Furthermore, since a conductive adhesive is used at one of the plurality of connection locations, electrical connection between the piezoelectric vibrating piece and the package side can be achieved at the one connection location. On the other hand, a non-conductive adhesive is used at the other joint of the plurality of connection points, but the non-conductive adhesive has a larger amount of adhesive (adhesive component) per unit area than the conductive adhesive. Therefore, the fixing performance is excellent.
Therefore, according to the present invention, it is possible to effectively prevent the vibration in the thickness direction of the piezoelectric vibrating piece and provide a bonded structure of the piezoelectric vibrating piece having excellent vibration characteristics.

Moreover, according to the structure of 1st invention, although a nonelectroconductive adhesive is used for the base side among several joining locations, a nonelectroconductive adhesive has a filler like a conductive adhesive. Therefore, it is softer and absorbs vibration more. Therefore, by placing this flexible adhesive on the base side that receives the vibration of the vibrating arm closer, it is possible to effectively prevent the vibration of the vibrating arm from leaking to the package side through the joint, and excellent vibration. Characteristics can be obtained. In addition, since electrode patterns having different polarities are generally formed on the base portion, the risk of short-circuiting can be prevented by making the adhesive disposed on the base side non-conductive.

The piezoelectric vibrating piece joining structure according to the present invention is further characterized in that the first adhesive is a silicone-based adhesive .

The piezoelectric vibrating piece joining structure according to the present invention is further characterized in that the second adhesive is a polyimide-based adhesive .

According to the fourth aspect of the present invention , the above-mentioned object has a base portion that supports two vibrating arms having long grooves , branches so as to extend from the base portion, and extends along the longitudinal direction of the vibrating arm. A piezoelectric fork device including a tuning-fork type piezoelectric vibrating piece having a plurality of fixing arms formed on the housing and a package containing the piezoelectric vibrating piece so as to join the fixing arms. Each of the fixing arms is provided in the order in which the first and second joints joined to the package are closer to the base, and the first arm than the first adhesive used for joining the first joints. The second adhesive used for joining the two joints is harder and conductive adhesive, and the first adhesive is a non-conductive adhesive, and further, the second joints Is arranged closer to the base than the tip of the long groove It is accomplished by a piezoelectric device being.

According to the configuration of the fourth invention , each of the plurality of fixing arms is provided with a plurality of joint portions with the package in the longitudinal direction, so that the thickness of the piezoelectric vibrating piece can be obtained by the same action as in the first invention. The swing of the direction can be suppressed. Furthermore, since a conductive adhesive is used at one of the plurality of connection locations, electrical connection between the piezoelectric vibrating piece and the package side can be achieved at the one connection location. And since a nonelectroconductive adhesive is used for the other joining location of a some connection location, fixing performance can be improved by the effect | action similar to 1st invention.
Therefore, according to the present invention, it is possible to effectively prevent the vibration in the thickness direction of the piezoelectric vibrating piece and to provide a piezoelectric device having excellent vibration characteristics.

1 and 2 show a piezoelectric device 20 according to an embodiment of the present invention. FIG. 1 is a schematic plan view of the piezoelectric device 20, and FIG. 2 is a schematic sectional view taken along line BB of FIG.
In addition, a piezoelectric device means all the products which accommodated the piezoelectric vibrating piece in the package irrespective of names, such as a piezoelectric vibrator and a piezoelectric oscillator.
1 are electrode patterns shown for convenience of understanding, and do not represent a cross section or the like. Further, in FIG. 2, the drawing is complicated, and thus the electrode pattern indicated by the parallel oblique lines in FIG.

The piezoelectric device 20 in these drawings shows an example in which a piezoelectric vibrator is configured, and the piezoelectric device 20 houses a piezoelectric vibrating piece 32 in a package 36 which is a base.
The package 36 has a rectangular shape. For example, the package 36 is formed by laminating a plurality of substrates formed by molding ceramic green sheets made of aluminum oxide as both insulating materials, and then sintering the laminate. As shown in FIG. 4, in this embodiment, the first substrate 36b and the second substrate 36a are stacked from the bottom.

The second substrate 36a is formed with a predetermined hole inside thereof so that a predetermined internal space S is formed inside the package 32 when stacked on the first substrate 36b. This internal space S becomes a cavity for accommodating the piezoelectric vibrating piece 32.
Further, in FIG. 2 of the second substrate 36 a, a brazing material 48 such as low melting point glass is applied to the opening end surface on the side opened upward, and the internal space S is sealed by the lid 39. Even after the lid is sealed, the lid 39 irradiates the metal coating portion such as the excitation electrode provided on the piezoelectric vibrating piece 32 with a laser beam so that the frequency can be adjusted by the mass reduction method. It is made of a transparent material, particularly a thin glass plate.

  The package 36 is a package (container) having a structure in which, for example, the first substrate 36b is used as a base, and the piezoelectric vibrating piece 32 is bonded to the substrate 36 and a thin box-shaped lid or lid is placed on the base. May be used.

In the case of the present embodiment, the first substrate 36b is a flat substrate, which constitutes the bottom of the package 36 and is a substrate that is bonded so that the piezoelectric vibrating reed 32 faces the first substrate 36b.
That is, in the width direction of the surface exposed to the internal space S of the first substrate 36b (the inner bottom surface of the package 36), as shown in FIG. 1, for example, the mount electrode 31 formed by nickel plating and gold plating on tungsten metallization. , 31 are provided. The mount electrodes 31 and 31 are electrodes for supplying a driving voltage to the piezoelectric vibrating piece 32, and are connected to the mounting terminals 39 and 39 on the bottom surface by conductive through holes or the like (not shown) so as to have different polarities. .
Then, conductive adhesives 43, 43 such as silicone, epoxy, or polyimide are applied as adhesives on the mount electrodes 31, 31, and the piezoelectric vibrating piece 32 is applied on the conductive adhesives 43, 43. Is mounted and the conductive adhesives 43 and 43 are cured, whereby the mount electrodes 31 and 31 on the package side and the piezoelectric vibrating piece 32 are electrically and mechanically connected.
The conductive adhesive 43 and the like will be described later in detail.

The piezoelectric vibrating piece 32 is made of, for example, a piezoelectric material such as quartz, and a piezoelectric material such as lithium tantalate or lithium niobate can be used in addition to the quartz.
In the case of the present embodiment, a so-called tuning fork type piezoelectric vibrating piece is used as the piezoelectric vibrating piece 32, and a pair of vibrating arms 34 and 35 extending in parallel with each other in order to obtain a required performance by forming a small size. The base 51 for supporting the pair of vibrating arms 34 and 35 and the fixing arms 37 and 38 branched from the base 51 are provided. The vibrating arms 34 and 35, the base 51, and the fixing arms 37 and 38 are integrally formed.

  The resonating arms 34 and 35 are divided into two forks from the base 51, and extend elongated toward the left in FIG. Further, the vibrating arms 34 and 35 are formed with long grooves 49 extending along the longitudinal direction (Y direction in FIG. 1) on the front and back surfaces (upper and lower surfaces in FIG. 2), and the cross section in the width direction is substantially H. It is a type. An excitation electrode 44 is formed in the long groove 49 of the vibrating arm 35, and excitation electrodes 45 are formed on both side surfaces of the vibrating arm 35 so as to face the excitation electrode 44 in the long groove 49. An excitation electrode 45 is formed in the long groove 49 of the vibrating arm 34, and excitation electrodes 44 are formed on both side surfaces of the vibrating arm 34 so as to face the excitation electrode 45 in the long groove 49. The excitation electrode 44 and the excitation electrode 45 have different polarities.

The base 51 is a portion for supporting the pair of vibrating arms 34 and 35, and excitation electrodes 44 and 45 for exciting the vibrating arms 34 and 35 are routed on the front and back surfaces thereof so as not to be short-circuited. Yes.
Furthermore, the base 51 of this embodiment is also a portion for supporting a plurality of fixing arms 37 and 38 for joining the piezoelectric vibrating piece 32 to the package 36 side.

The fixing arms 37 and 38 are portions formed so as to separate the joining portion of the piezoelectric vibrating piece 32 from the package 36 from the vibrating arms 34 and 35 rather than the base portion 51, and are formed so as to extend from the base portion 51. ing.
Specifically, the fixing arms 37 and 38 are formed so as to extend from the end of the base 51 opposite to the vibrating arms 34 and 35 to both sides in the width direction (X direction in FIG. 1). It is bent at a substantially right angle so as to be parallel to the vibrating arms 34 and 35. The fixing arm 37 and the fixing arm 38 are symmetric with respect to a central axis C that equally divides the width direction (X direction) into two. Thereby, the fixing arms 37 and 38 are paired so that the base 51 and the vibrating arms 34 and 35 are sandwiched therebetween.

Further, the fixing arms 37 and 38 are not short-circuited by forming a pair of fixing arms 37 and 38 branched from the base 51. That is, the fixing arms 37 and 38 are electrically connected to the mount electrodes 31 and 31 by the conductive adhesives 43 and 43, and are provided in portions where electrodes for applying a voltage to the excitation electrodes 44 and 45 are routed. Therefore, a pair of fixing arms 37 and 38 are formed instead of a single arm, and electrode patterns with different polarities (parts indicated by parallel diagonal lines in FIG. 1) are provided on each of them.
Specifically, the excitation electrode 44 is routed through the base 51 to the fixing arm 37, and the excitation electrode 45 is routed through the base 51 to the fixing arm 38. An electrode pattern (not shown) is drawn not only on the upper surface of FIG. 2 but also on the lower surface (surface facing the mount electrodes 31, 31), and the electrode pattern on the upper surface (parallel to FIG. 1). The hatched portion) is electrically connected to the electrode pattern (not shown) on the lower surface.

  The length L1 of the portion of the fixing arms 37, 38 along the longitudinal direction of the vibrating arms 34, 35 is set so that the dimension in the width direction (X direction in FIG. 1) of the piezoelectric vibrating piece 32 is minimized. Has been. That is, when the vibrating arms 34 and 35 are swung in the approaching / separating direction (the direction of arrow F in FIG. 1), the distal end portions 37a and 38a of the fixing arms 37 and 38 do not come into contact with the vibrating arms 34 and 35. The projections of the vibrating arms 34 and 35 are prevented from projecting beyond the tip of the long groove 49 that is a large bending point.

Here, each of the plurality of fixing arms 37 and 38 is provided with a plurality of joint portions (locations where an adhesive is applied) 52 and 54 with the package 36 in the longitudinal direction.
In the case of the present embodiment, the joint portions 52 and 54 of the fixing arm 37 and the joint portions 52 and 54 of the fixing arm 38 are substantially symmetric with respect to the central axis C, respectively, and the distal end side and the base portion, respectively. It is provided at two locations on the 51 side.
Since the joint portions 52 and 54 of the fixing arm 37 and the joint portions 52 and 54 of the fixing arm 38 have the same configuration, only the fixing arm 37 will be described below unless otherwise specified. To do.

In the fixing arm 37, the conductive adhesive 43 is used at one of the joint portions 52 and 54, and the non-conductive adhesive 42 is used at the other.
Specifically, the joint location 52 is provided on the distal end side, and the joint location 54 is provided on the base 51 side. The front end side and the base 51 side represent a relative positional relationship with each other, but in the case of the present embodiment, a virtual direction in the width direction (X direction in FIG. 1) passing through the center of gravity GP2 of the piezoelectric vibrating piece 32. A joining point 52 is formed on the tip side from the line GP3, and 54 is formed on the base 51 side.
The conductive adhesive 43 is used at the joint 52 on the tip side (tip portion 37a in this embodiment) from the virtual line GP3. On the other hand, a non-conductive adhesive 42 is used at the joint portion 54 on the base 51 side from the virtual line GP3 (in this embodiment, the corner portion 37b bent at a substantially right angle of the fixing arm 37).

As for the joint portion 52 of the distal end portion 37a, the conductive adhesive 43 is applied on the mount electrode 31 as described above, and the distal end portion 37a of the fixing arm 37 is placed on the conductive adhesive 43. Connection is made.
On the other hand, for the joint portion 54 of the corner portion 37b on the base 51 side, a pattern 33 is formed on the inner bottom surface exposed in the internal space S of the package 36, and a non-conductive adhesive 42 is applied on the pattern 33. Then, the corner portion 37b on the base 51 side is placed thereon.

As described above, the non-conductive adhesive 42 is used on the base 51 side among the plurality of joint portions 52 and 54, but the non-conductive adhesive 42 per unit area as compared with the conductive adhesive 43. Since there are many adhesive components, the fixing performance is excellent, and the base 51 side can be reliably fixed.
Moreover, since the non-conductive adhesive 42 does not have a conductive filler like the conductive adhesive 43, the non-conductive adhesive 42 is softer and can absorb more vibration. Therefore, by disposing the non-conductive adhesive 42 on the base 51 side that receives vibrations of the vibrating arms 34 and 35 closer, there is a risk that the vibrations of the vibrating arms 34 and 35 leak to the package 36 side through the joining region 54. Can be effectively prevented, and excellent vibration characteristics can be obtained.

  Preferably, for the conductive adhesive 43 and the non-conductive adhesive 42, a flexible silicone-based adhesive is used as a binder as an adhesive component. A silicone-based conductive adhesive in which a filler is dispersed may be used. As a result, the flexible silicone adhesive absorbs the vibration of the vibrating arms 34 and 35 well, effectively preventing the vibration from leaking to the package 36 through the bonding regions 52 and 54, and excellent vibration characteristics. Can be obtained.

  In the case where the piezoelectric device 20 is used in an electronic device that is hardly moved, such as a desktop personal computer, a polyimide-based adhesive may be used for the conductive adhesive 43 and the non-conductive adhesive 42. That is, the polyimide-based adhesive is inferior to the silicone-based in terms of flexibility, but is excellent in fixing force, so that the possibility that the piezoelectric vibrating piece 32 is peeled off from the package 36 can be prevented.

  More preferably, a flexible silicone-based adhesive is used for the joint portion 54 on the base 51 side among the plurality of joint portions 52 and 54, and the base 51 side side is used for the joint portion 52 on the distal end side. A polyimide-based adhesive that is harder than the bonding portion 54 but has a fixing force may be used. That is, at the joint 52, the piezoelectric vibrating piece 32 and the package 36 can be securely fixed by the fixing force of the polyimide conductive adhesive 43, and a hard polyimide adhesive is applied. Even so, the distal end portion 37a is farthest from the vibrating arms 34 and 35, so that it is less necessary to consider vibration leakage compared to the base 51 side. In addition, since the flexible silicone-based non-conductive adhesive 42 is used on the base 51 side, the vibration transmitted from the vibrating arms 34 and 35 to the tip 37a is also absorbed. Few. Therefore, by adopting such a configuration, it is possible to simultaneously obtain two contradictory effects of reliable fixing and prevention of vibration leakage.

Note that the pattern 33 on the base 51 side to which the non-conductive adhesive 42 is applied is provided to increase the connection strength between the package 36 and the piezoelectric vibrating piece 32 and the level of the piezoelectric vibrating piece 32. It is not intended to be a universal connection.
Specifically, the pattern 33 has the same thickness as the mount electrode 31. Further, it is made of substantially the same material so that it can be formed in the same manufacturing process as that of the mount electrode 31, and is formed by, for example, nickel plating and gold plating on a tungsten metallization, and along the width direction of the package 36 as shown in FIG. , And are provided entirely from the corner 37b to the corner 38b.

The embodiment of the present invention is configured as described above, and the plurality of fixing arms 37 and 38 to be joined to the package 36 are provided with a plurality of joint portions 52 and 54 in the longitudinal direction, respectively. Therefore, the joining locations 52 and 54 do not become fulcrums, and the oscillation of the piezoelectric vibrating piece 32 in the thickness direction can be suppressed.
Furthermore, since the conductive adhesive 43 is used at one of the plurality of connection locations, the piezoelectric vibrating reed 32 and the package 36 can be electrically connected at the one connection location 52. On the other hand, since the non-conductive adhesive 42 is used for the other joint portion 54 among the plurality of connection portions, the piezoelectric vibrating piece 32 and the package 36 can be reliably fixed.

In the case of the piezoelectric device 20 shown in FIGS. 1 and 2, the non-conductive adhesive 42 is used at the joining portion 54 on the base 51 side, so that it is not necessary to consider a short circuit. Therefore, the joint portion 54 on the base 51 side may be configured as shown in FIG.
That is, FIG. 3 is a schematic plan view of the piezoelectric device 22 according to the first modification of the above-described embodiment (the parts denoted by the same reference numerals as used in the description of FIGS. 1 to 3 are common configurations) Is).
As shown in this figure, it is not necessary to divide the joint portion 54 on the base 51 side into the fixing arm 37 and the fixing arm 38, and the joint portion 54 on the base 51 side of the fixing arm 37 and the fixing arm 38 are not connected. The non-conductive adhesive 42 may be applied so as to connect the joint portion 54 on the base 51 side.

In the case of the piezoelectric device 20 of FIGS. 1 and 2, the conductive adhesive 43 is used for the joint portion 52 on the distal end side, and the non-conductive adhesive 42 is used for the joint portion 54 on the base 51 side. However, in the case of a miniaturized piezoelectric device that particularly dislikes stray capacitance, the arrangement of the conductive adhesive 43 and the non-conductive adhesive 42 may be reversed as shown in FIG.
That is, FIG. 4 is a schematic plan view of the piezoelectric device 24 according to the second modification of the above-described embodiment (the parts denoted by the same reference numerals as used in the description of FIGS. 1 to 3 are common configurations) Is).

As shown in this figure, the conductive adhesive 43 is used at the joint portion 54 on the base 51 side among the plural joint portions 52 and 54 provided on the plurality of fixing arms 37 and 38, respectively. Yes. As a result, the portion that is to be electrically connected to the package 36 is close to the excitation electrodes 44 and 45, and it is possible to effectively prevent stray capacitance from being applied, and the conductivity is stabilized.
In addition, since conduction between the piezoelectric vibrating piece 32 and the package 36 side is achieved at the joint portions 54 and 54 on the base 51 side of the fixing arms 37 and 38, An electrode pattern becomes unnecessary. Therefore, the stray capacitance is more difficult to be applied and the continuity of the piezoelectric device 24 is stabilized.

In the piezoelectric device 24 of FIG. 4, the metal covering portions 56, 56 are provided at the joint portions 52, 52 on the distal end side of the fixing arms 37, 38 in order to improve the joining force with the nonconductive adhesive 42. Is formed.
Further, in the piezoelectric device 24 of FIG. 4, in order to achieve conduction on the base 51 side, mounts on the base 51 side of the inner bottom surface exposed to the internal space S of the package 36 and having opposite polarities at both ends in the width direction. Electrodes 31 and 31 are provided, and a conductive adhesive 43 is applied on the mount electrodes 31 and 31.

  The present invention is not limited to the above-described embodiment. Each configuration of the embodiment and each modified example can be appropriately combined or omitted, and can be combined with other configurations not shown.

1 is a schematic plan view of a piezoelectric device according to an embodiment of the present invention. FIG. 2 is a schematic sectional view taken along line BB in FIG. 1. The schematic plan view of the 1st modification of the piezoelectric device which concerns on embodiment of this invention. The schematic plan view of the 2nd modification of the piezoelectric device which concerns on embodiment of this invention. The schematic plan view of the conventional piezoelectric device. FIG. 6 is a cross-sectional view taken along line AA in FIG. 5.

Explanation of symbols

  20, 22, 24 ... piezoelectric device, 32 ... piezoelectric vibrating piece, 34,35 ... vibrating arm, 36 ... package, 37,38 ... fixing arm, 51 ... base, 52, 54 ... joints, 42 ... non-conductive adhesive, 43 ... conductive adhesive

Claims (4)

A tuning fork-type piezoelectric vibrating piece having a base for supporting two vibrating arms having long grooves, a plurality of fixing arms branched from the base and extending along the longitudinal direction of the vibrating arm Is a bonding structure of a piezoelectric vibrating piece that is bonded to a package with an adhesive,
Each of the plurality of fixing arms is provided in the order in which the first and second joint portions to be joined to the package are closer to the base, than the first adhesive used for joining the first joint portions. And the second adhesive used for joining the second joint location is harder and conductive adhesive, and the first adhesive is a non-conductive adhesive,
Further, the piezoelectric vibration reed joining structure is characterized in that the second joining location is arranged closer to the base side than the tip of the long groove . The piezoelectric vibrating piece joining structure according to claim 1, wherein the first adhesive is a silicone-based adhesive. 3. The piezoelectric vibrating piece joining structure according to claim 1 , wherein the second adhesive is a polyimide-based adhesive. A tuning-fork type piezoelectric device having a base portion for supporting two vibrating arms having long grooves, a branching branch extending from the base portion , and a plurality of fixing arms formed along the longitudinal direction of the vibrating arm. A piezoelectric device comprising a resonator element and a package for accommodating the piezoelectric resonator element so as to join the fixing arm,
Each of the plurality of fixing arms is provided in the order in which the first and second joint portions to be joined to the package are closer to the base, than the first adhesive used for joining the first joint portions. And the second adhesive used for joining the second joint location is harder and conductive adhesive, and the first adhesive is a non-conductive adhesive,
Further, the piezoelectric device is characterized in that the second joint location is disposed closer to the base than the tip of the long groove .

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