JP2012175405A - Piezoelectric vibrating element, piezoelectric vibrator, piezoelectric oscillator, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-frequency piezoelectric vibrating element having excellent frequency temperature characteristics, frequency reproducibility, and aging characteristics.SOLUTION: A piezoelectric vibrating element 1 includes: a piezoelectric substrate 5 having a thin vibrating area 7 and a U-shaped thick supporting section 8 integrally formed along three sides of the vibrating area; excitation electrodes 20a, 20b provided in the vibrating area; and lead electrodes 22a, 22b. The thick supporting section 8 includes: a first area 10; a second area 12, a third area 14; and a slit formed penetrating the third area. The slit includes: a first slit section 17 extending parallel to the first area 10 from a base end edge of the third area 14 and being terminated in a surface of the third area; and a second slit section 18 extending in a direction orthogonal to the first area from a terminal end of the first slit section 17 and being terminated in a surface of the third area 14.

Description

The present invention relates to a piezoelectric vibration element, a piezoelectric vibrator, a piezoelectric oscillator, and an electronic device in which stress caused by respective expansion coefficients of a piezoelectric substrate and a package that accommodates the piezoelectric substrate is reduced.

Surface mount type piezoelectric vibrators have excellent electrical characteristics such as small size, high accuracy and high stable frequency, and little change over time. Widely used as a frequency source. In recent years, along with the reduction in size and weight of devices, surface mount piezoelectric vibrators have been further reduced in size and height. In particular, miniaturization of a piezoelectric vibrator having a frequency-temperature characteristic exhibiting a smooth cubic curve in a wide temperature range and having little secular change is demanded from various directions.

Patent Document 1 discloses an AT-cut quartz crystal resonator that suppresses distortion caused by the crystal piece holding structure and improves vibration characteristics and impact resistance. In order to increase the frequency of the crystal piece, a concave portion is formed in a part of a flat plate-like piezoelectric substrate, and a flat portion in the concave portion is used as a vibrating portion. The crystal piece is provided with notches from both sides in the width direction between the vibration region and the holding end. The extraction electrode extended from the excitation electrode formed in the vibration part extends to the holding end of the crystal piece via the notch. The crystal resonator is configured to apply a conductive adhesive to a terminal electrode provided in a step portion of a container body, place a holding end on the terminal electrode, and connect and fix it.
The stress caused by the difference in thermal expansion between the container body and the crystal piece is concentrated in the portion where the conductive adhesive is applied, and distortion occurs. However, the generated stress is blocked by the notch and is not transmitted to the vibration region. As a result, it is disclosed that electrical characteristics such as frequency temperature characteristics can be maintained satisfactorily.

Japanese Patent Application Laid-Open No. 2004-228561 includes a quartz crystal vibrating portion, a holding member that holds the quartz vibrating portion, and a columnar support member that connects the two. The support member has one end serving as the quartz vibrating portion and the other end serving as the holding member. An AT-cut quartz crystal unit configured by coupling is disclosed.
Further, in Patent Document 3, a circular vibration portion, a ring-shaped support portion concentric with the vibration portion,
A crystal resonator including a bridge portion that connects a vibration portion and a support portion is disclosed.

JP 2004-88138 A JP 59-218019 JP 2007-36969 A

However, only a general shape is disclosed in Patent Document 1, and thereby, the shape of the vibration part, the shape of the notch part, and the shape dimension of the holding end of the crystal piece are accurately determined. That is extremely difficult.
In addition, when using the configuration disclosed in Patent Document 2 to reduce the size of the piezoelectric vibration element, it is necessary to form a U-shaped slit surrounding the vibration portion on the piezoelectric substrate. In order to form the slit, a slit width approximately equal to or larger than the plate thickness of the substrate is required. Therefore, there is a problem that the vibration part is reduced, and thus the CI value (crystal impedance) of the crystal resonator element is increased.
In addition, when the configuration disclosed in Patent Document 3 is applied to a rectangular piezoelectric substrate, the above-described vibration part is reduced, which causes a problem that the CI value of the crystal resonator element is increased.
The present invention has been made to solve the above-described problem. The piezoelectric vibrator is reduced in size, and stress generated due to a difference in linear expansion coefficient between the piezoelectric substrate and the package is suppressed, and excellent temperature characteristics are obtained. Another object of the present invention is to provide a piezoelectric vibration element, a piezoelectric vibrator, a piezoelectric oscillator having aging characteristics, and an electronic device using these.

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 vibration element according to the present invention includes a substantially rectangular vibration region, a U-shaped thick portion integrated along three sides excluding one side of the tip of the vibration region, A piezoelectric vibration element including excitation electrodes respectively disposed on the front surface and the back surface of the vibration region, wherein the thick portion includes a first region, a second region, and a third region that are thicker than the vibration region. The vibration region and the thick portion are configured as a piezoelectric substrate integrated with each other, the first region and the second region are disposed to face each other with the vibration region interposed therebetween, and the third region is the first region. The base region of the first region and the second region are connected to each other, the third region has a slit formed therethrough, and the slit extends from the base end edge of the third region to the first region and the second region. A first slit portion extending linearly in a first direction parallel to the two regions and terminating in the third region; A second slit portion that linearly extends in a second direction orthogonal to the first region and the second region from the end portion of the first slit portion and terminates in the third region. It is a piezoelectric vibration element characterized by having.

When the vibration region of the piezoelectric substrate is thinned to increase the frequency, it is easier to receive stress (strain) from the support portion on the package side that fixes the piezoelectric substrate. Therefore, by providing first and second slit portions penetrating the piezoelectric substrate in an L shape on one region supporting the vibration region and between the supported portion and the vibration region, As a result, the stress transmitted to the vibration region due to the portion can be significantly reduced. As a result, high frequency of the piezoelectric vibration element can be realized,
There is an effect that frequency temperature characteristics, frequency reproducibility, and aging characteristics are improved.

Application Example 2 In the piezoelectric vibration element, the first slit portion is displaced toward the first region or the second region along the side edge of the third region. The vibrating piezoelectric vibrating element according to Application Example 1, wherein the second slit portion extends from a terminal portion of the first slit portion toward the second region or the first region. .

By causing the first slit portion to be displaced to a position along the side edge of the first region or the third region on the second region side, the stress generated from the supported portion of the piezoelectric substrate is changed to the first slit. Since it is interrupted by the portion, there is an effect that the stress generated in the vibration region can be reduced.

Application Example 3 In the piezoelectric vibration element, at least a part of the first slit portion is
Application example 1 wherein the first region or the second region is located on the longitudinal extension.
It is a piezoelectric vibration element as described in above.

By positioning the first slit portion on the longitudinal extension of the first region or the second region, the stress generated from the supported portion of the piezoelectric substrate is blocked by the first slit portion, and the first region, or There is an effect that stress generated in the vibration region can be reduced without being transmitted to the second region.

Application Example 4 In the piezoelectric vibration element, the lead electrode is formed to extend from the excitation electrode on the thick portion on the opposite side facing the one side of the tip of the vibration region and on the back surface of the piezoelectric substrate, 4. The piezoelectric device according to any one of application examples 1 to 3, wherein a terminal portion of each lead electrode is spaced apart at a position of the third region along both end portions in the second direction. It is a vibration element.

By disposing the terminal portions of the lead electrodes at positions along both ends of the third region in the second direction (width direction), the stress generated from the supported portion of the piezoelectric substrate is changed between the first and second portions. Since it is blocked by the slit portion and transmitted to the vibration region via the periphery of the third region, there is an effect that the stress in the vibration region can be greatly reduced.

Application Example 5 In the piezoelectric vibration element, a narrow strip-like strip is positioned outside the first slit portion in the second direction, and the strip and the first slit portion are arranged. An area straddling the third area facing each other and the third area spaced from the area in the second direction;
Application example 2 characterized in that the piezoelectric vibration element is a supported portion when connecting and fixing on an insulating substrate.
5. The piezoelectric vibration element according to any one of 4 to 4.

Since the stress generated in the strip on the outside of the first slit portion is extremely small, one of the supported regions is a region straddling the strip and the third region facing each other with the first slit portion interposed therebetween. The effect of improving the impact resistance while maintaining the stress level generated in the vibration region at the minimum level by using the third region separated from the supported portion as the other supported portion. There is.

Application Example 6 In the piezoelectric vibration element according to any one of Application Examples 1 to 5, the piezoelectric substrate is an AT-cut quartz substrate.

A piezoelectric substrate as described above is formed using an AT-cut quartz crystal substrate, and an excitation electrode is formed on this piezoelectric substrate to form a piezoelectric vibration element, thereby providing good frequency temperature characteristics, frequency reproducibility, and aging. There is an effect that a high-frequency piezoelectric vibration element having excellent characteristics can be obtained.

Application Example 7 A piezoelectric vibrator according to the present invention includes the piezoelectric vibration element according to any one of Application Examples 1 to 6 and a package that accommodates the piezoelectric vibration element. It is a piezoelectric vibrator.

By housing the above-described piezoelectric vibration element in a package, there is an effect that a small-sized and high-frequency fundamental wave piezoelectric vibrator having excellent frequency temperature characteristics, frequency reproducibility and aging characteristics can be obtained.

Application Example 8 A piezoelectric oscillator according to the present invention is a piezoelectric oscillator according to any one of Application Examples 1 to 6, an IC component on which an oscillation circuit for exciting the piezoelectric vibration element is mounted, and the piezoelectric vibration. A piezoelectric oscillator comprising: a package for hermetically sealing an element and accommodating the IC component.

By configuring a piezoelectric oscillator including the above-described piezoelectric vibration element, an IC component, and a package, the effect of obtaining a compact and high-frequency piezoelectric oscillator having excellent frequency temperature characteristics, frequency reproducibility, and aging characteristics. There is. In addition, when a voltage controlled piezoelectric oscillator (VCXO) is configured, a piezoelectric resonator element is formed of a fundamental wave, so that a variable frequency range is wide, a frequency temperature characteristic and an aging characteristic are excellent, and a small and high frequency VCXO can be obtained. There is an effect.

Application Example 9 An electronic apparatus according to the present invention is an electronic apparatus including the piezoelectric vibrator according to Application Example 7.

By configuring the electrode device including the piezoelectric vibrator, it is possible to configure an electronic device including a reference frequency source having a high frequency and excellent frequency stability.

1 is a schematic plan view showing the structure of a piezoelectric vibration element according to the present invention. (A) is a top view of a piezoelectric vibration board | substrate, (b) is PP sectional drawing of (a), (c) is QQ sectional drawing of (a). The figure shown with the constant table of the ceramic package used for stress distribution simulation, a quartz substrate, and a conductive adhesive. The top view of a piezoelectric substrate and the stress distribution map which generate | occur | produces. The top view of a piezoelectric substrate and the stress distribution map which generate | occur | produces. The top view of a piezoelectric substrate and the stress distribution map which generate | occur | produces. The perspective view of a piezoelectric substrate and the stress distribution map which generate | occur | produces. The top view of a piezoelectric substrate and the stress distribution map which generate | occur | produces. Sectional drawing of a piezoelectric vibrator. Sectional drawing of a piezoelectric oscillator. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view showing a configuration of a piezoelectric vibration element 1 according to an embodiment of the present invention.
The piezoelectric vibration element 1 includes a thickness vibration piezoelectric substrate (hereinafter referred to as a piezoelectric substrate) 5 having a thin and substantially rectangular vibration region 7 and a U-shaped thick support portion 8, and front and back surfaces of the vibration region 7 facing each other. Excitation electrodes 20a and 20b formed on both sides of each of the electrodes, and lead electrodes 22a and 22b extending from the respective excitation electrodes 20a and 20b to the end of the piezoelectric substrate 5 are roughly provided.
2A is a plan view of the piezoelectric substrate 5, FIG. 2B is a sectional view taken along the line P-P in FIG. 2A, and FIG.
It is QQ sectional drawing of).

The piezoelectric substrate 5 is obtained by lapping and polishing a substrate made of a plate-like piezoelectric material cut out at a predetermined angle (about 35 ° 15 ′ in the case of a quartz AT-cut substrate) to obtain a surface roughness of the substrate and parallelism. The degree of flatness is finished to a predetermined accuracy. In order to increase the frequency of the piezoelectric substrate (for example, 150 MHz at the fundamental wave), the piezoelectric substrate having the vibration region 7 and the thick support portion 8 is processed using a photolithography technique and an etching technique. In order to maintain the cut angle accuracy of the vibration surface of the vibration region 7, only one surface of the piezoelectric substrate is processed into a concave shape, and the other surface often retains the original cut surface.
The piezoelectric substrate 5 is substantially rectangular and formed on one surface of the piezoelectric substrate 5 as in the embodiment shown in FIG. 2 except for the thin vibration region 7 and one side 7 a of the tip of the vibration region 7. Three sides 7b
, 7c, 7d, and a U-shaped thick support portion 8 integrated therewith. Piezoelectric substrate 5
The other surface is a flat surface that maintains the cutting angle. The thick support portion 8 includes a first region 10 and a second region 12 that are arranged to face each other with the vibration region 7 interposed therebetween, and a third region that continuously connects between the base end portions of the first and second regions 10 and 12. 14 and the slit 1 for stress relaxation formed through the third region 14
6 are provided.

Although the example using the quartz material of quartz AT cut was shown as the piezoelectric substrate 5, other cut angles,
SC cut or the like may be used. Further, other piezoelectric crystals, for example, piezoelectric substrates such as lithium tantalate, lithium niobate, and langasite may be used. In the embodiment of FIG. 1, the crystal axis direction is not shown, but in the case of crystal AT cut, the direction orthogonal to the surface of the piezoelectric substrate 5 is Y
'Axis. The longitudinal direction of the first region 10 (second region 12) is the X axis or the Z ′ axis. In the case of quartz, it is displaced in the X axis direction, and the displacement distribution in the X axis direction is wider than that of the Z ′ axis.
In some cases, the X-axis direction is longer than the length of the Z′-axis.

As shown in the embodiment of FIGS. 1 and 2, the stress relaxation slit 16 has a third region 14.
A first slit portion 17 linearly extending in a first direction parallel to the first and second regions 10 and 12 from the base edge 14A of the first region 17 and terminating in the plane of the third region 14; The second end that extends linearly in the second direction (width direction) orthogonal to the first and second regions 10 and 12 and ends within the inner surface of the third region 14 from the end portion of the slit portion 17. And an L-shape having a slit portion 18.
The third region 14 having the slit 16 in the plane is connected to the base edge of the vibration region 7 and extends in the second direction (width direction), and the base end of the second slit portion 18. A rectangular support piece base 14c positioned on the edge 14A side, one end of the support piece main body 14a, and the support piece base 14
a connecting piece 14b that connects between one end of c, and a narrow strip 14d that is connected to the other end of the support piece main body 14a and extends in the first direction.
In the embodiment shown in FIG. 1 and FIG. 2A, the example in which the two corners connected to the support piece main body 14a of the vibration region 7 are chamfered is shown. It shall be included in

The structure of the slit 16 will be described in detail. As shown in the embodiment of FIG. 1 and FIG.
The 1st slit part 17 which concerns on this example is located on the longitudinal direction (1st direction) extension of the 1st area | region 10, and the position along the side edge of the 3rd area | region 14 which is the 1st area | region 10 side. It is biased to. The second slit portion 18 extends from the terminal portion of the first slit portion 17 toward the second region toward the vibration region 7 in the second direction (width direction), and is in the plane of the third region 14. Terminated. That is, the third region 14 includes a support piece main body 14a that is connected to the side 7c of the vibration region 7, a connecting piece 14b that is displaced to the second region 12 side and connects the support piece main body 14a and the support piece base 14c, It has a support piece base portion 14c positioned at the end of the thick support portion 8 and a narrow strip-like strip piece 14d provided by being deviated toward the second region 12 side.
The first slit portion 17 is located on the extension of the second region 12 in the longitudinal direction, and the second
It may be configured to be shifted to a position along the side edge of the third region 14 on the region 12 side, and has the same function as described above.

The excitation electrodes 20a and 20b are respectively disposed on the front and back surfaces of the thin vibration region 7 as shown in the embodiment of FIG. The lead electrode 22a extending from the excitation electrode 20a toward the third region 14 passes through the thick support portion 8 on the opposite side facing the one side 7a of the distal end edge of the vibration region 7, and the base end edge 14A of the support piece base portion 14c. It is extended up to. The lead electrode 22b extending from the excitation electrode 20b formed on the other flat surface side toward the third region 14 passes through the flat surface on the back surface of the piezoelectric substrate 5, and then the back surface of the support piece body 14a and the back surface of the support piece base portion 14c. Is extended to the base end edge 14A of the support piece base 14c.
In the embodiment of FIG. 1, an example of the circular excitation electrodes 20 a and 20 b is shown, but it is not necessarily circular, and may be another shape, for example, a rectangle. An example of the electrode material is an electrode film of chromium Cr on the base and gold Au on the base.

As shown in the embodiment of FIG. 1, the terminal portions of the lead electrodes 22a and 22b of the piezoelectric vibration element 1 are spaced apart at positions along both ends of the third region 14 in the width direction (second direction). Then, it is bonded and fixed to an element mounting pad (not shown) formed on an insulating substrate (not shown) constituting the package of the piezoelectric vibrator via conductive adhesives 25a and 25b.
Further, on the outer side in the width direction of the first slit portion 17 of the piezoelectric vibration element 1 (upward in FIG. 1), a narrow strip 14d is formed. A conductive adhesive 25b is applied across the strip 14d and the surface of the edge 14A of the base portion 14c of the third region facing each other with the first slit portion 17 therebetween, and one lead electrode (FIG. 1) is applied. In this embodiment, it may be configured so as to achieve conduction between the terminal end 22B of 22b). Thus, since the piezoelectric substrate 5 is supported by both the support piece base 14c and the thin piece 14d, the piezoelectric vibration element 1 having high impact resistance can be obtained.

As shown in the embodiment of FIG. 1, the two supported portions 25a and 25b of the support piece base portion 14c of the piezoelectric vibration element 1 are bonded and fixed on an insulating substrate using a conductive adhesive or the like. In order to cure the adhesive, it is necessary to hold it at a high temperature, for example, 180 ° C. or higher for a predetermined time. In a high temperature state, both the piezoelectric substrate 5 and the insulating substrate expand and the adhesive temporarily softens, so that no stress is generated on the piezoelectric substrate 5. After the adhesive is cured, the temperature of the piezoelectric substrate 5 and the insulating substrate is set to room temperature (25
℃), the difference between the linear expansion coefficient of the insulating substrate and the linear expansion coefficient of the piezoelectric substrate 5
The stress generated from the fixation spreads over the vibration region 7 of the piezoelectric substrate 5.
In order to obtain the distribution of stress (strain) generated in the piezoelectric substrate, a simulation was performed using a finite element method. The smaller the stress in the vibration region, the frequency temperature characteristics, frequency reproducibility,
A piezoelectric vibration element having excellent aging characteristics can be obtained.
A piezoelectric vibrator is configured by hermetically housing the piezoelectric vibration element in a surface mounting package (comprising an insulating substrate and a lid). When the piezoelectric vibrator is mounted on a motherboard or the like and passed through a reflow furnace, the piezoelectric vibrator is exposed to a temperature of about 290 ° C. Therefore, in the simulation, when the temperature is lowered from 290 ° C. to 25 ° C., the piezoelectric vibrator is generated. We decided to analyze the stress distribution. The constants of ceramic PKG, crystal, and adhesive (epoxy system) used in the analysis are shown in FIG.
The numerical values shown in Fig. 1 were used. The reason why the epoxy adhesive is used is that the distortion is not large and the degassing is relatively small as will be described later.

The magnitude (stress level) of the stress generated in the piezoelectric substrate 5 is displayed in five levels (I, II, III, IV, V) from the maximum stress level I to the minimum stress level V in order to avoid complication of the drawing. To.
First, as shown in the plan view of FIG. 4, the piezoelectric substrate 5 has a U-shape that is connected along the vibration region 7 and three sides 7 b, 7 c, and 7 d excluding one side 7 a of the tip of the vibration region 7. Thick support part (first
A region 10, a second region 12, and a third region 14) 8. Further, the support piece body 14a
A stress distribution simulation is performed on a piezoelectric substrate that is integrally formed with a narrow strip-shaped connecting piece 14b connected to the central portion of the substrate and a rectangular region base portion 14c connected to the other end of the connecting piece 14b. went.
As shown by the solid line, broken line, and alternate long and short dash line in FIG. 4, the support piece base portion 14 c has the maximum stress level I in almost the entire region. The narrow strip-shaped connecting piece 14b has a stress level II in an approximately 1/3 area near the support piece base 14c, an approximately 2/3 area near the vibration area 7, and an area in the central portion of the support piece main body 14a. Becomes the stress level III. The vibration region 7 connected to the central portion of the support piece body 14a
As a result of simulation, it was found that a part of the vibration level 7 is a stress level IV and that most of the vibration region 7 is a stress level V. In the piezoelectric substrate having the shape shown in FIG. 4, the support piece main body 1 in the vibration region 7.
As a result of simulation, it was found that a region having a stress level IV is generated in a part near the center of 4a.

Next, as shown in FIG. 5, the piezoelectric substrate 5 includes a vibration region 7 and one side 7 a of the tip of the vibration region 7.
U-shaped thick support portions (first region 10, connected along three sides 7b, 7c, 7d)
Second region 12 and support piece body 14a) 8. Further, a narrow strip-shaped connecting piece 14b connected to the center of the supporting piece main body 14a, a rectangular supporting piece base 14c connected to the other end of the connecting piece 14b, the first region 10 and the supporting piece main body 14a. And a connecting portion between the second region 12 and the support piece main body 14a, and a strip 14d extending in the longitudinal direction of each of the first region 10 and the second region 12, respectively. The stress distribution was simulated for the piezoelectric substrate 5.
As shown by the solid line, broken line, and alternate long and short dash line in FIG. 5, the support piece base portion 14 c has the maximum stress level I in almost the entire region. The narrow strip-shaped connecting piece 14b has a stress level II in the approximately 2/3 region near the support piece base 14c, and the remaining approximately 1/3 region and the region in the central portion of the support piece main body 14a are stressed. Level III. As a result of the simulation, it was found that a part of the vibration region 7 connected to the central portion of the support piece main body 14a has the stress level IV, and most of the vibration region 7 has the stress level V. In the piezoelectric substrate 5 having the shape shown in FIG. 5, the support piece main body 14 a in the vibration region 7.
As a result of the simulation, it was found that a region of the stress level IV is generated in a part near the center of the region.

Next, a stress distribution simulation was performed on the piezoelectric substrate having the shape described in the embodiment of FIGS. As shown in FIG. 6, the support piece base 14c has a maximum stress level I in the entire region.
It becomes. The stress distribution is concentrated in the narrow strip-shaped connecting piece 14b, and the maximum stress level I to the maximum stress level IV are continuously concentrated in a small region of the connecting piece 14b. That is, the approximately 1/5 region near the support piece base 14c is the stress level I, and the approximately 1/5 region of the connecting piece 14b is the stress level II. The remaining approximately 3/5 region of the connecting piece 14b is a region of stress level III and stress level IV. As a result of simulation, it has been found that the support piece main body 14a, the first region, the second region, and the vibration region 7 have the stress level V.
4 to 6, the stress distribution on the piezoelectric substrate 5 is shown in a plan view, but the stress distribution is calculated in three dimensions, and FIG. 7 is a perspective view showing the stress distribution. Even in the thickness direction of the narrow strip-shaped connecting piece 14b, the stress levels II, III, and IV are almost continuously concentrated in a small region in the connecting piece 14b, and the support piece main body 14a, the first region, and the second region are concentrated. The region and the vibration region 7 are at the stress level V. That is, it can be seen that the stress rapidly decreases in the connecting piece 14b.

The piezoelectric substrate 5 shown in FIG. 8 includes a vibration region 7, a U-shaped first region 10, a second region 12, and a support piece main body 14 a that are connected along three sides of the vibration region 7. ing. Furthermore, it has a narrow strip-like connecting piece 14b connected to the center of the other side and a frame-like (frame-like) support piece 15 connected to the other end of the connecting piece 14b, and is integrally formed. Piezoelectric substrate. The frame-shaped support piece 15 has a frame shape in which the ends of the four support pieces 15a, 15b, 15c and 15d are connected to each other. The frame-shaped support piece 15 is fixed at two places on the wide support piece 15a.
As shown by the solid line, broken line, and alternate long and short dash line in FIG. 8, most of the wide support pieces 15 a have the maximum stress level I. Stress level II and stress level II near the both ends of the wide support piece 15a, respectively.
Stress levels III and IV are mixed in the support pieces 15c and 15d connected to both ends of the wide support piece 15a. On the support pieces 15c and 15d connected to both ends of the support piece 15b facing the wide support piece 15a, there is a region where the stress becomes the stress level V. On the thin support piece 15b connected to the connecting piece 14b, the stress in the area connected to the connecting piece 14b is at the stress level V, but there may be areas where the stress level IV is present on both sides of this area. found.

The stress distribution was also simulated for piezoelectric substrates with other shapes. Among them, it was found that the piezoelectric substrate with the shapes of FIGS. 6 and 8 had a stress level V in all vibration regions 7. It was. That is, when the piezoelectric vibration element is configured so that the stress generated in the vibration region 7 is reduced when a temperature load (from 290 ° C. to 25 ° C.) is applied to the piezoelectric substrate, the frequency temperature characteristics, heat cycle characteristics, aging Excellent characteristics. However, the piezoelectric substrate shown in FIG. 8 has a drawback that it is weaker than the piezoelectric substrate of FIG.

As shown in the embodiment of FIG. 1, when the vibration region 7 of the piezoelectric substrate 5 is thinned to increase the frequency, the stress (strain) from the supported portions 25 (25a, 25b) of the piezoelectric substrate 5 is reduced. More susceptible to damage. Therefore, the piezoelectric substrate 5 is penetrated in an L shape between the supported portion 25 (25a, 25b) and the vibration region 7 on one region (third region 14) that supports the vibration region 7. By providing the first and second slit portions 17 and 18, there is an effect that the stress transmitted to the vibration region 7 due to the supported portions 25 (25a and 25b) can be significantly reduced.
As a result, there is an effect that the high-frequency piezoelectric vibration element 1 with improved frequency temperature characteristics, frequency reproducibility, and aging characteristics can be realized.
Further, by shifting the first slit portion 17 to a position along the side edge of the third region 14 on the first region 10 side or the second region 12 side, the supported portion 25 (25a of the piezoelectric substrate). 25b
) Is interrupted by the first slit portion 17, so that the stress generated in the vibration region 7 can be reduced.
Further, by positioning the first slit portion 17 on the longitudinal extension of the first region 10 or the second region 12, the stress generated from the supported portion 25 (25a, 25b) of the piezoelectric substrate 5 is increased.
There is an effect that the stress generated in the vibration region 7 can be reduced without being transmitted to the first region 10 or the second region 12 by being blocked by the first slit portion 17.

As shown in the embodiment of FIG. 1, the terminal portions of the lead electrodes 22a and 22b are connected to the third region 14.
The piezoelectric substrate 5 is spaced apart at positions along both end portions in the second direction (width direction).
The stress generated from the supported portions 25 (25a, 25b) of the first and second slit portions 17
18 and is transmitted to the vibration region 7 via the periphery of the third region 14, so that the stress in the vibration region 7 can be greatly reduced.
Further, as shown in the embodiment of FIG. 6, since the stress generated in the outer strip 14d of the first slit portion 17 is extremely small, the strip 14d and the first slit 17 are sandwiched between them. The third region separated from the supported portion is defined as one supported portion on the opposite third region.
By using the other supported portion on the region, it is possible to improve the impact resistance while maintaining the stress level of the vibration region at the minimum level.
Also, the piezoelectric substrate 5 shown in the embodiment of FIG. 2 is formed using an AT-cut quartz substrate, and the excitation electrodes 20a and 20b are formed on the piezoelectric substrate 5 to form the thickness vibration piezoelectric vibration element 1. Therefore, there is an effect that a high-frequency piezoelectric vibration element having excellent frequency temperature characteristics and excellent frequency reproducibility and aging characteristics can be obtained.

FIG. 9 is a cross-sectional view showing a configuration of the piezoelectric vibrator 2 according to the second embodiment of the present invention. The piezoelectric vibrator 2 includes the piezoelectric vibration element 1 and a package that accommodates the piezoelectric vibration element 1. The package includes a package body 40 formed in a rectangular box shape, and a lid member 52 made of metal, ceramic, glass or the like.
As shown in FIG. 9, the package body 40 is formed by laminating a first substrate 41, a second substrate 42, and a third substrate 43, and an aluminum oxide ceramic as an insulating material. -It is formed by forming a green sheet into a box and then sintering it. Mounting terminal 4
A plurality of 5 are formed on the outer bottom surface of the first substrate 41. The central portion of the third substrate 43 is removed, and a metal seal ring 44 such as Kovar is formed on the upper peripheral edge of the third substrate 43.
The third substrate 43 and the second substrate 42 form a recess that accommodates the piezoelectric vibration element 1. A plurality of element mounting pads 47 that are electrically connected to the mounting terminals 45 by conductors 46 are provided at predetermined positions on the upper surface of the second substrate 42.
The position of the element mounting pad 47 is arranged so as to correspond to the end portion of the lead electrode formed on the support piece base portion 14c when the piezoelectric vibration element 1 is mounted.

The configuration of the piezoelectric vibrator 2 is such that the conductive adhesive 50 is applied to the element mounting pad 47 of the package body 40.
For example, an appropriate amount of any of a silicon-based adhesive, an epoxy-based adhesive, a polyimide-based adhesive, a bismaleimide-based adhesive, and the like is applied, and the piezoelectric vibration element 1 is placed thereon and a load is applied. As a characteristic of the conductive adhesive, the magnitude of the stress (strain) caused by the adhesive is silicon adhesive,
It becomes larger in the order of epoxy adhesive and polyimide adhesive. In addition, degassing increases in the order of polyimide adhesive, epoxy adhesive, and silicon adhesive. Epoxy adhesives are characterized by relatively little distortion and relatively low outgassing. Further, in the embodiment of FIG. 1, the conductive adhesive 25a that is the supported portion 25 that is far from the connecting piece 14b is made of a hard adhesive and the conductive material that is the supported portion 25 that is close to the connecting piece 14b. For the adhesive 25b, a soft adhesive may be used to reduce the stress generated in the vibration region 7.

In order to cure the conductive adhesives 25a and 25b of the piezoelectric vibrator 1 mounted on the package main body 40, it is placed in a high temperature furnace at a predetermined temperature for a predetermined time. After the annealing treatment, the frequency is adjusted by adding mass to the excitation electrodes 20a and 20b or reducing the mass. The lid member 52 is seam welded to the seal ring 44 formed on the upper surface of the package body 40. Or
There is also a method in which the lid member 52 is placed on the low melting point glass applied to the upper surface of the package main body 40 and melted and adhered. The package cavity is evacuated or filled with an inert gas such as nitrogen N 2 to complete the piezoelectric vibrator 2.
In the above-described embodiment of the piezoelectric vibrator 2, an example in which a laminated plate is used for the package body 40 has been described. A piezoelectric vibrator may be configured.
By accommodating the piezoelectric vibration element 1 of the embodiment shown in FIG. 1 in the package of the embodiment shown in FIG. 9, it is excellent in frequency temperature characteristics, frequency reproducibility, and aging characteristics, and is small and has a basic high frequency. There is an effect that a wave piezoelectric vibrator can be obtained.

FIG. 10 is a cross-sectional view showing the configuration of the piezoelectric oscillator 3 according to the third embodiment of the present invention.
The piezoelectric oscillator 3 includes the above-described piezoelectric vibration element 1, an IC component 78 on which an oscillation circuit for exciting the piezoelectric vibration element 1 is mounted, and the piezoelectric vibration element 1 is sealed with vacuum or nitrogen N 2 gas and the IC component 7
8 is provided with a package main body 60 that accommodates 8 and a lid member 75.
In the piezoelectric oscillator 3 shown in FIG. 11, the IC component 78 is not hermetically sealed. However, the IC component 78 may be disposed inside the package and hermetically sealed.
As shown in the embodiment of FIG. 10, by configuring the piezoelectric oscillator 3 including the piezoelectric vibration element 1, the IC component, and the package, the frequency temperature characteristics, frequency reproducibility, and aging characteristics are excellent. There is an effect that a small and high frequency piezoelectric oscillator 3 can be obtained. Further, when the voltage controlled piezoelectric oscillator (VCXO) is configured, since the piezoelectric vibration element 1 is formed of a fundamental wave, the frequency variable width is wide, the frequency temperature characteristics and the aging characteristics are excellent, and a small and high frequency VCXO is obtained. There is an effect that it is.

FIG. 11 is a schematic configuration diagram showing a configuration of an electronic apparatus according to the present invention. The electronic device 4 includes the piezoelectric vibrator 2 described in the second embodiment. Examples of the electronic device 4 using the piezoelectric vibrator 2 include a mobile phone and a transmission device. In these electronic devices 4, the piezoelectric vibrator 2 is used as a reference signal source, a voltage variable piezoelectric oscillator (VCXO), or the like.
An electronic device with favorable characteristics can be provided.
By configuring the electrode device 4 including the piezoelectric vibrator 2 of the embodiment shown in FIG. 9, there is an effect that an electronic device including a reference frequency source having a high frequency and excellent frequency stability can be configured.

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibration element, 2 ... Piezoelectric vibrator, 3 ... Piezoelectric oscillator, 4 ... Electronic equipment, 5 ... Piezoelectric substrate (piezoelectric substrate), 7 ... Vibration area | region, 8 ... Thick-wall support part, 10 ... 1st area | region, 12 ... 2nd area | region, 14 ... 3rd area | region, 14a ... support piece main body, 14b ... connection piece, 14c ... support piece base part, 14d ... strip, 1
6 ... slit, 17 ... first slit portion, 18 ... second slit portion, 20a, 20b ... excitation electrode, 22a, 22b ... lead electrode, 25 ... supported portion, 25a, 25b ... conductive adhesive, 40 , 60 ... package main body, 41 ... first substrate, 42 ... second substrate, 43 ... third substrate, 44 ... metal seal ring, 45, 65 ... mounting terminal, 46, 66 ... conductor, 47 ... element mounting Pad 52, 75 ... Lid member 54, Component mounting pad 69, 76 ... Metal bump 76,
78 ... IC parts

Claims (9)

A substantially rectangular vibration region, a U-shaped thick portion integrated along three sides excluding one side of the tip of the vibration region, and excitation electrodes respectively disposed on the front and back surfaces of the vibration region; A piezoelectric vibration element comprising:
The thick part is composed of a first region, a second region, and a third region that are thicker than the vibration region,
The vibration region and the thick part are configured as a piezoelectric substrate integrated with each other,
The first region and the second region are disposed opposite to each other with the vibration region interposed therebetween,
The third region is connected between the base end portions of the first region and the second region,
The third region has a slit formed therethrough,
The slit extends linearly in a first direction parallel to the first region and the second region from the base edge of the third region, and terminates in the third region; A second slit portion that linearly extends in a second direction orthogonal to the first region and the second region from the end portion of the first slit portion and terminates in the third region. A piezoelectric vibration element characterized by comprising: The first slit portion is deviated toward the first region side or the second region side along the side edge of the third region, and the second slit portion is the first slit portion. 2. The piezoelectric vibration element according to claim 1, wherein the piezoelectric vibration element extends from a terminal portion of the slit portion toward the second region or the first region. 2. The piezoelectric vibration element according to claim 1, wherein at least a part of the first slit portion is located on a longitudinal extension of the first region or the second region. Lead electrodes are formed to extend from the excitation electrode on the thick portion on the opposite side facing the one side of the tip of the vibration region and on the back surface of the piezoelectric substrate, respectively, and the end portion of each lead electrode is formed by the second electrode.
4. The piezoelectric vibration element according to claim 1, wherein the piezoelectric vibration element is spaced apart from each other at positions of the third region along both ends in the direction. A narrow strip-shaped strip is located outside the first slit portion in the second direction, and on the third region facing the strip with the first slit portion interposed therebetween. The region extending over the region and the third region spaced from the region in the second direction serve as a supported portion when the piezoelectric vibration element is connected and fixed on the insulating substrate. 4. The piezoelectric vibration element according to any one of 4 above. The piezoelectric vibration element according to claim 1, wherein the piezoelectric substrate is an AT-cut quartz substrate. A piezoelectric vibrator comprising: the piezoelectric vibration element according to claim 1; and a package that accommodates the piezoelectric vibration element. The piezoelectric vibration element according to claim 1, an IC component on which an oscillation circuit for exciting the piezoelectric vibration element is mounted, the piezoelectric vibration element is hermetically sealed, and the IC component is accommodated. And a piezoelectric oscillator.   An electronic apparatus comprising the piezoelectric vibrator according to claim 7.

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