JP2001077652A - Piezoelectric vibrator and piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator and a piezoelectric oscillator which hardly receives the effects of external vibration and can be small. SOLUTION: A piezoelectric vibrator 10 is provided with a piezoelectric vibration element 11 and a base 12 for housing the piezoelectric vibration element. The piezoelectric vibration element is fixed to an electrode 14, formed at the base with a conductive adhesive 16 to be sealed within the base. In this case, the adhesive 16 has hardness equal to or softer than the pencil hardness B and is applied on the electrode 14 with a thickness equal to or larger than 30 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a piezoelectric vibrator or a piezoelectric oscillator in which a piezoelectric vibrating element is mounted on a base and sealed.

[0002]

2. Description of the Related Art Conventionally, piezoelectric vibrators are hard disk drives (HDDs).
Disk drives), mobile computers, small information devices such as IC cards, and mobile communication devices such as mobile phones, car phones, and paging systems are widely used.

[0003] Such a piezoelectric vibrator is constituted by accommodating a piezoelectric vibrating element formed of a quartz vibrating piece or the like in a package using, for example, a ceramic base or the like.

That is, such a quartz vibrating piece is formed in a substantially rectangular plate shape, and is a piezoelectric vibrating element having a necessary driving electrode formed on the surface thereof, and is electrically connected to an electrode provided on a ceramic base. After being mounted as much as possible, the lid is put on and sealed.

[0005] Here, the piezoelectric vibrating element is usually provided with two relatively long ends at one end on an electrode formed on a base to form a relatively hard epoxy or polyimide conductive adhesive. Is fixed.

[0006]

However, in the piezoelectric vibrator having such a configuration, when mounted on the above-described portable telephone device or the like, vibration is externally applied by, for example, dropping off the device (hereinafter, referred to as "external vibration"). And the frequency characteristics may be adversely affected.

FIG. 11 shows spurious characteristics of a piezoelectric vibrator when an external vibration is applied to such a mounted device. The resonance caused by the external vibration affects the vibration characteristics of the piezoelectric vibrator. As shown in (A), there was a disadvantage that spurious components increased. The structure of the piezoelectric vibrator is, for example, that shown in FIG.

In FIG. 1, a piezoelectric vibrator 1 has a piezoelectric vibrating element 5 sealed in a package having a cap 3 covered with a flange 2 a formed on the periphery of a base 2. The piezoelectric vibration element 5 is fixed as follows.

That is, a pair of spring members 6 and 6 are fixed on a flexible substrate 4 set on the upper surface of the base 2,
Two points at both ends of the piezoelectric vibration element 5 are fixed to the spring members 6 and 6 by conductive adhesives 7 and 7, respectively.
Leads 8, 8 drawn out are connected to the spring members 6, 6, respectively.

In the piezoelectric vibrator 1 as shown in FIG. 12, the spring members 6 and 6 support two points at both ends of the piezoelectric vibrating element 5, so that they are hardly affected by external vibration. Since the members 6 and 6 are arranged below the piezoelectric vibration element 5, the thickness of the entire package increases. That is, the spring materials 6, 6
Has a height indicated by H in the drawing, so that the package accommodating it has a large thickness, and there is a limit in reducing the thickness of the package, and it is difficult to cope with the miniaturization of the above-described mounted device. Will be.

It is an object of the present invention to provide a piezoelectric vibrator and a piezoelectric oscillator which are less susceptible to external vibrations and which can be constructed in a small size.

[0012]

According to a first aspect of the present invention, there is provided a piezoelectric vibrating element comprising: a piezoelectric vibrating element; and a base for accommodating the piezoelectric vibrating element. A piezoelectric vibrator formed by fixing the piezoelectric vibrating element with a conductive adhesive and sealing the piezoelectric vibrating element in the base, wherein the conductive adhesive has a hardness lower than the B hardness, and the electrode This is achieved by a piezoelectric vibrator, applied above with a thickness of 30 μm or more.

According to the first aspect of the present invention, the piezoelectric vibrating element has a conductive adhesive (hereinafter, referred to as a “soft conductive adhesive”) having a hardness lower than the Empitz hardness B and a thickness of 30 μm or more with respect to the base electrode. Agent). For this reason, even when external vibration is applied to the device on which the piezoelectric vibrator is mounted, the vibration is transmitted from the outside of the package to the conductive adhesive and is absorbed. For this reason, the vibration due to the external vibration is damped, and the spurious characteristics of the piezoelectric vibrator are prevented from being adversely affected.

According to a second aspect of the present invention, in the configuration of the first aspect, the piezoelectric vibrating element is formed in a plate shape that is long in one direction, and one end of the piezoelectric vibrating element is cantilevered at two places. It is characterized by being fixed and supported by a conductive adhesive.

According to the second aspect of the invention, in addition to the function of the first aspect, since one end of the piezoelectric vibrating element is fixed in a cantilever manner at two places by the conductive adhesive, the piezoelectric vibrating element is fixed. It is not necessary to form a support structure at both ends of the element with a spring material or the like, and a configuration similar to that of the related art can be employed. Therefore, the thickness of the entire device can be reduced.

According to a third aspect of the present invention, in the configuration of the first aspect, the piezoelectric vibrating element is formed in a plate shape that is long in one direction, and each of the two ends of the piezoelectric vibrating element is connected to the conductive adhesive. It is characterized in that it is fixed by an agent and is supported at two places of a double-supported type.

According to the third aspect of the present invention, even if both ends of the piezoelectric vibrating element are supported, a certain amount of elasticity is provided by using a soft conductive adhesive, so that a supporting spring material is required. Therefore, the thickness of the entire apparatus can be reduced.

According to a fourth aspect of the present invention, in the configuration of the third aspect, the piezoelectric vibrating element is located on a center line along a longitudinal direction thereof.
It is characterized in that it is supported at a location.

According to the structure of the fourth aspect, the piezoelectric vibration element can be reliably supported from both ends in the longitudinal direction, and its vibration characteristics are not impaired.

According to a fifth aspect of the present invention, in the configuration of the first aspect, the piezoelectric vibrating element is formed in a substantially rectangular plate shape that is long in one direction, and each corner of a short side at one end of the piezoelectric vibrating element is provided. A total of three places, that is, two places of the portion and near the center of the opposite side on the other end side, are fixed and supported by the conductive adhesive.

According to the fifth aspect of the present invention, since the three points of the piezoelectric vibrating element are fixed, the piezoelectric vibrating element can be more reliably supported.

According to a sixth aspect of the present invention, there is provided a piezoelectric vibrating element comprising: a piezoelectric vibrating element; and a base for accommodating the piezoelectric vibrating element. A piezoelectric oscillator in which an element is fixed with a conductive adhesive and an integrated circuit is mounted on the base and sealed in the base, wherein the conductive adhesive has a hardness softer than the E hardness. This is achieved by a piezoelectric oscillator having and applied over the electrode with a thickness of 30 μm or more.

According to the configuration of the sixth aspect, the same action as the first aspect can be exhibited in the piezoelectric oscillator.

According to a seventh aspect of the present invention, in the configuration of the piezoelectric oscillator according to the sixth aspect, the piezoelectric vibrating element is formed in a plate shape elongated in one direction, and one end of the piezoelectric vibrating element is cantilevered. It is characterized in that it is fixed and supported by the conductive adhesive at a location.

According to an eighth aspect of the present invention, in the configuration of the piezoelectric oscillator according to the sixth aspect, the piezoelectric vibrating element is formed in a plate shape that is long in one direction. It is characterized in that it is fixed by a conductive adhesive and is supported at two locations of a double-supported type.

According to a ninth aspect of the present invention, in the configuration of the piezoelectric oscillator of the eighth aspect, the piezoelectric vibrating element is supported at two positions on a center line along a longitudinal direction of the piezoelectric vibrating element.

According to a tenth aspect of the present invention, in the piezoelectric oscillator according to the first aspect, the piezoelectric vibrating element is formed in a substantially rectangular plate shape that is long in one direction, and a short side at one end of the piezoelectric vibrating element. In this case, a total of three places, that is, two places at each corner and near the center of the opposite side at the other end, are fixed and supported by the conductive adhesive.

According to the configuration of claims 7 to 10, the effects of claims 2 to 5 can be exhibited in the piezoelectric oscillator.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing a schematic configuration of a piezoelectric vibrator according to an embodiment of the present invention.

The piezoelectric vibrator 10 is joined to, for example, a box-shaped base 12 having a space 12a for accommodating a plate-shaped piezoelectric vibration element 11, and the base 12 so as to seal the space 12a. For example, a plate-shaped lid 13 is provided.

Here, the term "piezoelectric vibrating element" means a piezoelectric vibrating reed in which a piezoelectric material is arranged in a predetermined shape, on which a driving electrode is formed.

As shown, the piezoelectric vibrating element 11 is formed in a substantially rectangular plate shape as a whole, and a metal film is formed on the surface of a step portion having one end 11a integrally provided in the space 12a. The electrodes 14, which are arranged by
14 are connected and fixed via soft conductive adhesives 16 and 16, and the other end 11b is a free end. Base 12
The lid 13 is joined via, for example, a sealing material (a brazing material) 15.

Here, as a material of the piezoelectric vibrating element 11, for example, quartz is used, and a necessary electrode is formed on a quartz vibrating piece. As a material of the base 12, a ceramic such as alumina is used.
As the material of No. 3, metal such as Kovar or ceramic such as alumina is used. In addition, as a material of the sealing material 15, low melting point glass, silver brazing, solder, or the like is used.

Here, as the soft conductive adhesive 16, for example, a silicon-based or urethane-based conductive adhesive is used, and in particular, an adhesive softer than the Empitz hardness B is used.

The soft conductive adhesive 16 is applied to the electrode 1
4 is applied to a thickness of 30 μm or more and 120 μm or less.

Here, in order to form a predetermined height on the base 12 and secure electrical connection, the thickness of the soft conductive adhesive 16 needs to be 20 μm or more. Further, as described later, a thickness of 30 μm or more is required to prevent spurious characteristics from deteriorating due to external vibration.

FIG. 2 is a schematic sectional view showing the structure of an embodiment of the piezoelectric oscillator according to the present invention.

In FIG. 2, the portions denoted by the same reference numerals as those in FIG. 1 have the same configuration.

In the figure, the base 22 of the piezoelectric oscillator 20
In FIG. 1, a step portion is further provided below the internal space 12a as compared with FIG. 1 to form another internal space 12b one step lower. The integrated circuit 21 is housed in the internal space 12 b on the conductive pattern formed on the upper surface of the base 22, and is connected to the electrode 23. As a result, a predetermined drive voltage is applied to the piezoelectric vibration element 11 to cause it to vibrate, and its output is input to the integrated circuit 21 to extract a signal of a predetermined frequency.

In this piezoelectric oscillator 20, the base 2
When the piezoelectric vibration element 11 is fixed to the second electrode 24, the soft conductive adhesive 16 is used.

FIG. 3 is a schematic plan view showing a state where the lid 13 of FIG. 1 is removed.

In the figure, both ends of a short side 11c of one end (fixed end) of the piezoelectric vibrating element 11, that is, both corners of one end of the piezoelectric vibrating element 11 are arranged on the electrodes 14, 14, and the soft conductive Applying the adhesives 16, 16 to the piezoelectric vibrating element 1
1 shows a state in which 1 is cantilevered and fixed at two places.

Then, in a vacuum atmosphere, the lid 13 shown in FIG.
Is sealed to form the piezoelectric vibrator of the present embodiment.

The present embodiment is configured as described above. According to the piezoelectric vibrator 10, when it is driven,
As shown in FIG. 4, even when external vibration is applied in a required vibration frequency band, a spurious peak due to the influence of the resonance frequency as described with reference to FIG. 11 does not occur. .

That is, the piezoelectric vibrating element 11 is
Since the piezoelectric vibrator 10 is fixed to the second electrode 14 by the soft conductive adhesive 16 having a soft hardness equal to or greater than the hardness B, even if external vibration is applied to the piezoelectric vibrator 10, the vibration is not generated. 12 to conductive adhesive 16
It is transmitted to and absorbed.

Therefore, the vibration due to the external vibration is suppressed, and the spurious characteristics of the piezoelectric vibrator 10 are not adversely affected.

Here, in order to obtain good spurious characteristics, the soft conductive adhesive 16 is preferably made of an Empitz hardness B
It is necessary that a softer adhesive be used and the thickness of the electrode 14 should be not less than 30 μm and not more than 120 μm.
m or less.

FIG. 9 is a graph showing the characteristics when the thickness of the soft conductive adhesive 16 is 10 μm.

As shown, the spurious peak B has moved to a relatively low frequency band, but still remains.

FIG. 10 shows this soft conductive adhesive 1
6 is a graph showing the characteristics when the thickness of No. 6 was set to 20 μm.

As shown, the spurious peak C appears in almost the same frequency band as in FIG. 9, but its value is small, and the soft conductive adhesive 16
It can be seen that the vibration damping action by is working to some extent.

As described above, considering the results of FIGS. 4, 9 and 10, the thickness of the soft conductive adhesive 16 is almost 3
0 μm or more was found necessary, and the upper limit was 120 μm in order to satisfy the bonding and conduction stability and workability.
It is about.

Further, the spurious characteristics as described above are:
In the piezoelectric oscillator 20 shown in FIG.
In the case where is used, it is improved in exactly the same way.

FIG. 5 is a schematic plan view of a piezoelectric vibrator 30 according to a second embodiment of the present invention.

In the figure, the portions denoted by the same reference numerals as those in the first embodiment have the same configuration, and thus the duplicate description will be omitted, and the following description will focus on the differences.

In the piezoelectric vibrator 30, the piezoelectric vibrating element 1
1, both ends of the short side 11c at one end (fixed end), ie,
The two corners of one end of the piezoelectric vibrating element 11 are arranged on the electrodes 14, 14, and not only the soft conductive adhesive 16, 16 is applied but also the short side 11 d on the other end opposite to the short side 11 c. Also, the flexible conductive adhesive 16 is applied and fixedly supported at three places.

The portion of the short side 11d to which the soft conductive adhesive 16 is applied is divided into two parts with respect to the width W of the piezoelectric vibrating element 11, that is, the longitudinal part so that W1 = W2. It is set on a virtual center line C1 extending in the direction.

Accordingly, in addition to the operation and effect of the first embodiment, the piezoelectric vibrating element 11 is fixed on the base 12 at three points, and both ends of the piezoelectric vibrating element 11 are fixed. It is less likely to be affected by the vibration, and the operation accuracy is improved. Moreover, since the piezoelectric vibrating element 11 is fixed by the soft conductive adhesive, it is not necessary to use a spring material having elasticity so as not to hinder the vibration of the piezoelectric vibrating element 11 due to its original function. For this reason, since the piezoelectric vibrator 30 does not become large in the thickness direction, it is possible to sufficiently cope with downsizing of the mounted device.

FIG. 6 is a schematic plan view of a piezoelectric vibrator 40 according to the third embodiment of the present invention. In the drawings, the portions denoted by the same reference numerals as those in the first and second embodiments have the same configuration, and thus the overlapping description will be omitted, and the following description will focus on the differences.

The piezoelectric vibrator 40 includes the piezoelectric vibrating element 11
Are fixed on the virtual center line C1 and provided on each of the short sides 11c and 11d of the piezoelectric vibrator 11 to support two points.

That is, the electrodes 14 of the base 12
Are provided at both ends in the longitudinal direction of the base 12 along the width direction, that is, along the right edge and the left edge.

An electrode (not shown) is provided on the piezoelectric vibrating element 11 corresponding to the electrodes 14. Each of the short sides 11 c and 11 c of the piezoelectric vibrator 11 is set so as to conduct the electrodes 14 and 14 and the electrode on the side of the piezoelectric vibrating element 11.
d of each electrode 1 so as to be located on the virtual center line C1 of d.
Soft conductive adhesives 16, 16 are applied on 4, 14.

As a result, also in this embodiment, the first
Similar to the embodiment, when external vibration is applied, spuriousness does not increase, and in particular, since both ends of the piezoelectric vibration element 11 are supported at two points, the support performance is further improved.

FIG. 7 is a schematic plan view of a piezoelectric vibrator 50 according to a fourth embodiment of the present invention. In the drawings, the portions denoted by the same reference numerals as those in the first to third embodiments have the same configuration, and thus the overlapping description will be omitted, and the following description will focus on the differences.

In the piezoelectric vibrator 50, the configuration of the electrodes 14, 14 provided on the base 12 is the same as that of the third embodiment. Then, each short side 11c and 1 of the piezoelectric vibrating element 11
1d, soft conductive adhesives 16, 1
6 is set.

As a result, substantially the same functions and effects as those of the third embodiment can be obtained.

FIG. 8 shows a comparative example of the present invention.

In the figure, the portions denoted by the same reference numerals as those in the embodiment of FIG. 5 have the same configuration. In this example, as compared with the embodiment of FIG. 5, the fixed portion on the short side 11d side is located at the lower corner in the figure.

When such a configuration is adopted, the fixing point on the short side 11d side, that is, the application point of the soft conductive adhesive 16 is different from the configuration of FIG.
When the piezoelectric vibrator 60 is operated, a disadvantage occurs.
That is, in FIG. 8, the vertices of the triangular region indicated by oblique lines are fixed, while the remaining regions are not fixed, so that the balance of the piezoelectric vibration element 11 against the external vibration is lost. Vibration performance will be hindered. Thus, the configuration as shown in FIG. 8 is not preferable for practical use.

The present invention is not limited to the above embodiment. For example, when the softness of the soft conductive adhesive is softer than that of B, another kind may be used.
On the short side on one side of the piezoelectric vibrating element 11, not only two but also more fixed portions may be provided.

The second to fourth embodiments can be directly applied to the piezoelectric oscillator shown in FIG. Furthermore, the configuration of each part of each embodiment can be arbitrarily combined.

[0073]

As described above, according to the present invention, it is possible to provide a piezoelectric vibrator and a piezoelectric oscillator which are hardly affected by external vibrations and which can be constructed in a small size.

[Brief description of the drawings]

FIG. 1 is a partially cut-away schematic perspective view showing a first embodiment of a piezoelectric vibrator according to the present invention.

FIG. 2 is a schematic sectional view showing an embodiment of the piezoelectric oscillator of the present invention.

FIG. 3 is a schematic plan view showing a state where a lid of the piezoelectric vibrator of FIG. 1 is removed.

FIG. 4 is a graph showing spurious characteristics of the piezoelectric vibrator of FIG. 1;

FIG. 5 is a schematic plan view showing a second embodiment of the piezoelectric vibrator of the present invention.

FIG. 6 is a schematic plan view showing a third embodiment of the piezoelectric vibrator of the present invention.

FIG. 7 is a schematic plan view showing a fourth embodiment of the piezoelectric vibrator of the present invention.

FIG. 8 is a schematic plan view of a piezoelectric vibrator shown as a comparative example.

FIG. 9 is a graph of a comparative example showing spurious characteristics of a piezoelectric vibrator in which the thickness of a soft conductive adhesive is reduced.

FIG. 10 is another graph of a comparative example showing spurious characteristics of a piezoelectric vibrator in which the thickness of the soft conductive adhesive is reduced.

FIG. 11 is a graph showing spurious characteristics of a conventional piezoelectric vibrator.

FIG. 12 is a schematic sectional view showing an example of a piezoelectric vibrator.

[Explanation of symbols]

 Reference Signs List 10, 30, 40, 50 Piezoelectric vibrator 11 Piezoelectric vibrating element 12 Base (housing) 12a Internal space 13 Lid 14 Electrode 15 Sealing material 16 Soft conductive adhesive 20 Piezoelectric oscillator

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J079 AA04 BA23 BA49 FB12 HA03 HA04 HA07 HA13 KA05 5J108 AA01 BB02 CC04 EE03 EE07 EE18 FF14 GG03 GG20 JJ04

Claims (10)

[Claims] 1. A piezoelectric vibrating element comprising: a piezoelectric vibrating element; and a base for accommodating the piezoelectric vibrating element. The piezoelectric vibrating element is fixed to an electrode formed on the base by a conductive adhesive. A piezoelectric vibrator sealed in the conductive adhesive, wherein the conductive adhesive has a hardness softer than the Empitz hardness B, and is applied with a thickness of 30 μm or more on the electrode, Piezoelectric vibrator. 2. The piezoelectric vibrating element is formed in a plate shape that is long in one direction. One end of the piezoelectric vibrating element is cantilevered and fixed and supported by the conductive adhesive at two places. The piezoelectric vibrator according to claim 1. 3. The piezoelectric vibrating element is formed in a plate shape which is long in one direction, and one end of each end of the piezoelectric vibrating element is fixed by the conductive adhesive and two ends of the piezoelectric vibrating element are provided. The piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrator is supported. 4. The piezoelectric vibrator according to claim 3, wherein the piezoelectric vibrator is supported at two positions on a center line along a longitudinal direction of the piezoelectric vibrating element. 5. The piezoelectric vibrating element is formed in a substantially rectangular plate shape that is long in one direction, and two short-side corners at one end of the piezoelectric vibrating element and opposing sides at the other end. The piezoelectric vibrator according to claim 1, wherein a total of three locations near the center of the piezoelectric vibrator are fixed and supported by the conductive adhesive. 6. A piezoelectric vibrating element, comprising: a base for accommodating the piezoelectric vibrating element; fixing the piezoelectric vibrating element to an electrode formed on the base with a conductive adhesive; A piezoelectric oscillator having an integrated circuit mounted thereon and sealed in the base, wherein the conductive adhesive has a hardness lower than the B hardness, and a thickness of 30 μm or more on the electrode. A piezoelectric oscillator, wherein the piezoelectric oscillator is applied. 7. The piezoelectric vibrating element is formed in a plate shape that is long in one direction, and one end of the piezoelectric vibrating element is cantilevered and fixed and supported by the conductive adhesive at two places. 7. The piezoelectric oscillator according to claim 6, wherein: 8. The piezoelectric vibrating element is formed in a plate shape that is long in one direction, and one end at each of both ends of the piezoelectric vibrating element is fixed by the conductive adhesive at two positions of a double-supported type. 7. The piezoelectric oscillator according to claim 6, wherein said piezoelectric oscillator is supported. 9. The piezoelectric oscillator according to claim 8, wherein said piezoelectric oscillator is supported at two points on a center line along a longitudinal direction of said piezoelectric vibration element. 10. The piezoelectric vibrating element is formed in a substantially rectangular plate shape that is long in one direction, and two ends of each corner of one short side of one end of the piezoelectric vibrating element and opposing sides on the other end side. 7. The piezoelectric oscillator according to claim 6, wherein a total of three locations near the center of the piezoelectric oscillator are fixed and supported by the conductive adhesive.