JP2002353766A - Piezo device - Google Patents

Abstract

(57) Abstract: A quartz resonator having a package in which a lid of a thin glass plate is joined to an upper surface of a rectangular box-shaped base on which a thin ceramic plate is laminated is provided in a recess in an inner surface of the lid. The connection terminal 16 is formed, and the tuning-fork type quartz vibrating piece 1 is formed thereon.
4, the base end portion 14a is fixedly held by a conductive adhesive 17 in a cantilever manner. The crystal vibrating reed is connected to the internal terminals 18 and 19 provided on the joint surfaces of the lid and the base with a conductive adhesive 24 and to the external terminals 20 on the bottom of the base via a wiring circuit inside the base. Make it conductive. On the base, an IC chip 29 for driving a crystal vibrating piece and a crystal vibrating piece 34 of a different oscillation frequency / different or the same type can be mounted. The sealing hole 25 on the bottom of the base is hermetically closed with a sealing material 26 in a vacuum atmosphere after the lid is joined, and thereafter, a laser beam is irradiated from outside the lid to fine-tune the frequency of the quartz vibrating piece. . [Effect] A piezoelectric device such as a piezoelectric vibrator, a piezoelectric oscillator, and a composite vibrator can be further reduced in size and thickness. The package is sealed with a high degree of vacuum, and the frequency can be finely adjusted after sealing, thereby realizing high quality and high stability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric device such as a piezoelectric vibrator / piezoelectric oscillator or a SAW device used for various electronic devices, and more particularly, to a method in which a glass lid is attached to a base made of an insulating material such as ceramic. The present invention relates to a piezoelectric device for hermetically sealing a resonator element made of a piezoelectric material such as quartz in a package bonded with a melting point glass.

[0002]

2. Description of the Related Art Conventionally, in consumer and industrial electronic devices such as watches, home appliances, various information / communication devices and OA devices, piezoelectric vibrators, piezoelectric vibrating reeds and IC chips have been used as clock sources for their electronic circuits. Piezoelectric devices, such as oscillators and real-time clock modules, in which the components are sealed in the same package, are widely used. In particular, in the field of small information devices such as mobile computers and IC cards, and communication devices such as mobile phones, piezoelectric devices have been further reduced in size and thickness as the devices have become smaller and thinner. There is a demand for a surface mount type piezoelectric device suitable for mounting the device on a circuit board.

In general, a surface mount type piezoelectric device is known which has a structure in which a piezoelectric vibrating reed and, if necessary, electronic components are hermetically sealed in a package in which a lid is joined to a base made of an insulating material. For example, in a piezoelectric vibrator illustrated in FIG. 11, a base 2 constituting a package 1 has a rectangular box shape in which thin plates of an insulating material are laminated, and a transparent glass thin plate lid 3 is joined to an upper surface thereof, and a tuning fork is placed therein. The piezoelectric vibrating reed 4 is mounted. The frequency of the piezoelectric vibrating reed 4 can be finely adjusted by irradiating a laser beam from outside after the package 1 is sealed. Further, a piezoelectric oscillator can be obtained by mounting an IC chip which is an oscillation circuit for driving the piezoelectric vibrating reed 4 on the bottom surface of the base 2 or in a recess provided on the bottom surface.

Recently, Japanese Patent Application Laid-Open No. 2000-59169 discloses that a motherboard can be mounted at a high density in an electronic device such as a computer using a plurality of types of crystal units.
A piezoelectric vibrator array in which a plurality of press-fit sealed piezoelectric vibrators are arranged in parallel in order to save space, and are integrally molded and sealed. According to the publication, particularly when the piezoelectric vibrators are arranged with their leads reversed, wiring becomes easy, and in addition to miniaturization, improvement in mass productivity and cost reduction can be achieved.

[0005]

In the above-mentioned conventional piezoelectric vibrator or oscillator, the piezoelectric vibrating piece is housed in a box-shaped base and the lid is joined and sealed, so that the thickness is further reduced. It is difficult to plan. In particular, in the recent communication technology field, for example, it is required to mount a plurality of oscillators having different oscillation frequency bands on one electronic device. In addition, radio clocks, which have become very popular recently, have a function of automatically adjusting the time by receiving the standard time radio wave.However, in order to receive radio waves of different frequencies in the region or country of use, the oscillation frequency A multi-channel type having a plurality of different crystal units is desirable. In order to cope with further miniaturization of these electronic devices, a plurality of piezoelectric vibrators are required.
Piezoelectric devices such as composite oscillators and composite oscillators housed in individual packages are required. However, Japanese Patent Application Laid-Open
In the conventional structure described in Japanese Patent No. 000-59169, since the press-fit sealing type piezoelectric vibrator in which the piezoelectric vibrating pieces are hermetically sealed is individually integrated in each package, the size of the entire piezoelectric device increases accordingly. There is a limit to miniaturization.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a surface mount type piezoelectric device which can be further reduced in size and thickness. It is in. Further, the object of the present invention is to adjust the frequency of the piezoelectric vibrating piece with high precision, to secure a low CI value by sealing the inside of the package to a high degree of vacuum,
An object of the present invention is to provide a piezoelectric device having higher quality and excellent stability.

[0007]

According to the present invention, to achieve the above object, a box-shaped base made of an insulating material and a thin lid made of a glass material joined to the upper surface of the base are provided. And a piezoelectric vibrating piece hermetically sealed in the package, wherein the lid has a recess on the inner surface thereof, and the piezoelectric vibrating piece is mounted in the recess. A piezoelectric device is provided.

[0008] With this configuration, first,
Since the package of the piezoelectric device can be made thinner, and at the time of assembling the package by bonding the lid to the base, the risk of damaging the piezoelectric vibrating piece due to contact with a jig or the like is reduced, Assembly work becomes easier.

[0009] In one embodiment, the base has a sealing hole at the bottom for communicating the inside and the outside of the package, and the sealing hole is closed by a sealing material from the outside. A package having such a structure, after bonding the lid to the base, placing the package in a predetermined gas atmosphere such as vacuum or nitrogen and closing the sealing hole, thereby providing a higher vacuum inside the package. Alternatively, it can be hermetically sealed in a gas atmosphere.

Further, according to the present invention, various elements which are preferably mounted in the same package can be mounted on the base side. In certain embodiments, various electronic components, such as, for example, IC chips, capacitors, resistors, etc., can be mounted on a base and hermetically sealed in a package.
When the electronic component is an oscillation circuit of the piezoelectric vibrating reed, a piezoelectric oscillator is configured.

In one embodiment, the base has a terminal on the joint surface with the lid, the lid has a terminal on the joint surface with the base, and the terminal on the base side and the terminal on the lid side are electrically connected. It is connected. Thus, the wiring circuit on the base side can be connected to the external terminal provided on the bottom surface of the surface mount package via the wiring circuit on the lid side.

In this case, the terminal on the base side and the terminal on the lid side can be electrically connected using a conductive adhesive.
Further, if at least the outside is covered with a cushioning material, the conductive adhesive may be damaged or peeled off due to an external force due to dropping or a jig for handling the piezoelectric device at the time of assembly, and the electrical connection may be lost. This is preferable because it reduces the number of the components.

In one embodiment, a piezoelectric vibrating reed is cantilevered at its base end with a conductive adhesive in the concave portion of the lid, and the peripheral edge of the concave portion is a piezoelectric vibrating reed. Are provided close to each other along the base end of the base. This facilitates the positioning of the piezoelectric vibrating reed when disposing it in the recess of the lid. Furthermore, since the conductive adhesive fills the gap between the base end of the piezoelectric vibrating reed and the periphery of the recess, sufficient mount strength can be obtained with a relatively small amount of the conductive adhesive, and the piezoelectric vibrating reed can be used. It can be fixed sufficiently firmly.

In another embodiment, a concave portion is formed on the outer peripheral edge of the base end portion of the piezoelectric vibrating reed. The conductive adhesive filled in the gap between the base end of the piezoelectric vibrating piece and the peripheral edge of the concave portion is preferable because it easily accumulates in the concave portion and can be prevented from spreading to an unnecessary portion beyond the concave portion.

In another embodiment, at least two such recesses are formed between a pair of extraction electrodes provided at the base end of the piezoelectric vibrating reed. The conductive adhesive attached to each of the extraction electrodes accumulates in the concave portion closer to the extraction electrode, but it can be prevented from flowing beyond this to the other extraction electrode, so that a short circuit between both extraction electrodes is reliably prevented. be able to.

Further, in another embodiment, the corner of the base end of the piezoelectric vibrating reed and the corner of the recess adjacent thereto are rounded to the same extent. Accordingly, the conductive adhesive is attached so as to cover the corners of the base end, so that the mounting strength can be increased and the piezoelectric vibrating reed can be more firmly fixed.

Also, in one embodiment, the recess of the lid comprises:
A second recess is formed in a region corresponding to the tip of the piezoelectric vibrating reed. Accordingly, even if the tip of the piezoelectric vibrating piece vibrates or vibrates largely due to an impact due to a drop or an external mechanical vibration, there is little possibility that the piezoelectric vibrating piece collides with the bottom surface of the base and is broken, thereby improving the shock resistance.

In another embodiment, the lid has a step provided along the inner periphery of the joint surface with the base. By aligning this step with the inner peripheral edge of the joining surface of the box-shaped base, the positioning of the lid to the base can be facilitated accurately, particularly without using separate positioning means. .

As the piezoelectric vibrating reed of the present invention, a tuning fork type or thickness shear mode piezoelectric vibrating reed or a SAW (surface acoustic wave) element can be used. In particular, when a tuning fork type piezoelectric vibrating piece is mounted, even if a weaker laser beam is irradiated from outside through a thin glass lid after the package is sealed, the metal weight material provided at the tip of the tuning fork vibrating arm is used. And fine adjustment of the frequency can be performed with high accuracy.

In another embodiment, a second base mounted on a base is provided.
, A composite piezoelectric vibrator composed of two piezoelectric vibrators of different oscillation frequencies and different or the same type is configured. When the second piezoelectric vibrating reed is a tuning fork type piezoelectric vibrating reed, particularly when the first piezoelectric vibrating reed is also a tuning fork type piezoelectric vibrating reed, in addition to the above-described advantages of the miniaturization and thinning of the package, For example, it is possible to easily cope with a case where a multi-channel type having a different oscillation frequency depending on use conditions such as a use area such as a radio clock is required.

In this case, it is preferable that the two piezoelectric vibrating reeds are supported in a cantilever manner at the base end thereof, and are disposed such that the base end and the front end are opposite to each other. With this, even if the tips of both piezoelectric vibrating pieces greatly shake or vibrate up and down due to the impact due to the drop or the mechanical vibration from the outside,
They are less likely to collide with each other and be damaged, thereby improving the impact resistance.

In one embodiment, the tuning fork type piezoelectric vibrating reed, which is the first or second piezoelectric vibrating reed, is provided on the first electrode formed on each main surface of the resonating arm and on each side surface of the resonating arm. A drive electrode comprising the formed second electrode, wherein the first electrode is
It is formed of an electrode film formed on a side surface of a groove provided on at least one main surface of each vibrating arm along a longitudinal direction thereof.
A tuning-fork type piezoelectric vibrating reed having such a grooved vibrating arm structure is known, for example, as described in JP-A-56-65517, and generates an electric field parallel to the main surface of the vibrating arm. It is known that the electric field efficiency can be greatly increased by this, and thereby the CI (crystal impedance) value can be suppressed low.

However, if a gas such as air is present in the package or a sufficient degree of vacuum cannot be obtained when the vibrating arm performs the bending motion, an extra groove provided on the main surface of the vibrating arm becomes unnecessary. Due to the air resistance, as the tuning fork type piezoelectric vibrating piece becomes smaller and smaller with the miniaturization and miniaturization of the piezoelectric device, the bending motion of the vibrating arm is restricted, and the expected CI value decreases. There is a possibility that it cannot be obtained. According to the present invention, the inside of the package can be sealed at a high degree of vacuum by closing the sealing hole provided in the base bottom portion with the sealing material from the outside after joining the lid to the base, so that the vibrating arm , A sufficient bending motion is secured, and a sufficient decrease in the CI value can be obtained.

Further, the tuning-fork type piezoelectric vibrating reed has a constricted portion formed at the base end thereof, for example, by the recess formed at the outer peripheral edge of the base end for storing the conductive adhesive as described above. Alternatively, it can be provided between a portion fixed to the lid and the vibrating arm. In this tuning-fork type piezoelectric vibrating reed, the vibration of the vibrating arm is interrupted by the constricted portion and does not reach the fixed portion of the base end portion, so that the vibrating arm can bend more freely and the CI value is suppressed to a lower value. You.

However, the bending motion of the vibrating arm is particularly difficult to reduce the size of the piezoelectric device because the constricted portion receives extra air resistance when a gas such as air exists in the package or a sufficient degree of vacuum cannot be obtained. As the tuning-fork type piezoelectric vibrating reed is reduced in size and miniaturized with miniaturization and miniaturization, the bending motion of the resonating arm is restricted, so that the expected decrease in CI value may not be obtained. In this case as well, the inside of the package can be sealed to a high degree of vacuum by closing the sealing hole provided on the base bottom portion from the outside after joining the lid, so that the vibrating arm is freer. The bending motion can be secured, and a sufficient decrease in the CI value can be secured.

[0026]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In each of the drawings, similar components are denoted by the same reference numerals. FIGS. 1A to 1C schematically show a configuration of a quartz oscillator which is a first embodiment of a piezoelectric device to which the present invention is applied. This crystal resonator includes a package 13 having a base 11 and a lid 12, and a tuning-fork type crystal resonator element 14 is hermetically sealed therein. The base 11 is shown in FIG.
As shown in FIG. 2 (B), it is formed in a substantially rectangular box shape in which a plurality of ceramic thin plates are laminated. The lid 12 is formed of a rectangular thin plate made of a transparent glass material, and is hermetically joined to the upper end surface of the base 11 with a low-melting glass (not shown) as in the related art.

As shown in FIG. 2, the lid 12 has a recess 15 formed in the inner surface thereof, and a tuning-fork type quartz vibrating piece 14 is mounted therein. Such a recess can be easily formed by a known technique, for example, by etching the surface of a thin glass plate, or by an integral molding method such as stamping of a glass material. A pair of connection terminals 16 are formed at one longitudinal end of the bottom surface of the recess 15, and the tuning-fork type quartz vibrating piece 14 is electrically conductively bonded on the connection terminal 16 at the base end 14 a thereof. It is cantilevered with an agent 17 and is held substantially horizontally in the recess 15.

From each connection terminal 16, an internal terminal 18 for wiring is drawn out to two corners of the cover 12 on the side of the base end 14a of the vibrating reed over both front and back surfaces. These terminals 16 and 18 are formed, for example, by vapor deposition or sputtering of a metal wiring material, or by etching a metal wiring material formed on the inner surface of the lid 12. At this time, the peripheral edge of the recess 15 is preferably formed as an inclined surface as shown in the figure so that the metal wiring material is not disconnected at the corner of the step. In addition, such a lid can form the external shape while patterning the terminal by etching a thin glass plate having an electrode film formed on the surface, and can obtain good dimensional accuracy and positional accuracy.

Internal terminals 19 for wiring are provided at two corners corresponding to the internal terminals 18 on the upper end surface of the base 11. Further, on the bottom surface of the base 11, external electrodes 20 and 21 are provided at each corner. Each internal terminal 19 on the upper end face of the base is connected to a via hole 22
And the same base end portion 14 of the resonator element via the wiring pattern 23.
Each is connected to the external electrode 20 on the a side. The internal terminal 18 of the corresponding lid and the internal terminal 19 of the base are electrically connected by, for example, a conductive adhesive 24, so that the tuning-fork type quartz vibrating piece 14 can be electrically connected to the external electrode 20. At this time, if at least the outside of the conductive adhesive 24 is covered with a cushioning material so as to preferably completely cover the conductive adhesive 24, the conductive material may be caught by an external force due to a drop or the like or a jig for handling the piezoelectric device at the time of assembly may be caught. This is preferable because the possibility that the conductive adhesive is damaged or peeled off and the electrical connection is lost is reduced.

Further, the base 11 is provided with a small-diameter circular sealing hole 25 which penetrates substantially the center of the bottom surface and is closed with a suitable sealing material 26. The filling of the sealing material 26
After joining the lid 12 to the base 11, for example, a metal ball 2 of Au-Sn or the like is placed on the step 25 ′ of the sealing hole in a vacuum environment.
7 is mounted and welded with a laser beam or the like. By having such a structure, the crystal resonator of the present embodiment can realize high-precision frequency adjustment of the resonator element and a high degree of vacuum inside the package as described in detail below.

In the process of manufacturing the crystal resonator of the present embodiment, the tuning frequency of the tuning-fork type crystal resonator element 14 is roughly adjusted to a predetermined frequency range when mounted on the lid 12. Next, the lid 12 is joined to the base 11 to be integrated, and a conductive adhesive 24 is applied to make the internal terminals 18 of the lid and the internal terminals 19 of the base conductive. This package is placed in a vacuum atmosphere, and the step 25 of the sealing hole 25 is placed as described above.
The Au-Sn ball placed on the 'is welded by a laser beam, whereby the sealing hole 25 is closed with a sealing material 26 and the package 13 is vacuum-sealed. Therefore, the gas generated from the conductive adhesive for fixing the quartz-crystal vibrating piece 14 to the lid 12, the gas generated when the lid 12 is bonded to the base 11 with the low-melting glass, and the expansion thereof are reduced by the sealing holes 27. And a high degree of vacuum inside the package can be secured after sealing.

In this state, while measuring the frequency through the internal terminal 18 or the external electrode 20 exposed on the outer surface of the lid 12,
The oscillation frequency is reduced by irradiating a laser beam 28 from outside through the lid 12 and partially removing the metal weight material in the frequency adjustment region provided at the tip portion 14b of each vibrating arm of the tuning fork type quartz vibrating piece 14. Fine tune. Especially recess 15
Since the glass is thin, even if a weaker laser beam is applied from the outside of the lid 12 than before, the fine adjustment of the frequency can be performed with high precision by removing the metal weight material provided at the tip of each of the vibrating arms. it can.

In this embodiment, the package can be made thinner by arranging the quartz-crystal vibrating piece in the recess on the inner surface of the lid. In addition, when assembling the package by joining the lid to the base, the risk of damaging the crystal vibrating reed by contact with a jig or the like is reduced, so that the assembling work is facilitated, and the working efficiency and productivity are improved. I do. In addition, since the frequency of the crystal resonator element can be finely adjusted with high precision after the package is sealed and the inside of the package can be sealed with a high degree of vacuum, a lower CI value can be secured, and higher quality and superior performance stability can be achieved. The obtained crystal oscillator is obtained.

The space defined inside the box-shaped base 11 can be used relatively freely. For example, various electronic components such as an IC chip, a capacitor, and a resistor are arranged in the same package 13. Various airtight devices such as a piezoelectric oscillator can be configured by airtight sealing. Further, by further mounting the second piezoelectric vibrating reed on the base 11, a composite piezoelectric vibrator including two piezoelectric vibrators of different oscillation frequencies, different types or the same type can be configured.

In the embodiment shown in FIG. 3, the tuning fork type quartz vibrating piece 14 is used.
The IC chip 29 that constitutes the oscillation circuit is mounted on the bottom surface of the space of the base 11. A wiring pattern 30 is formed on the bottom surface of the space, and I
It is electrically connected to the C chip 29. A part of the wiring pattern 30 is connected to the external terminal 21 on the bottom surface of the base 11 via a circuit 32 inside the base 11, and another part is connected to the tuning fork type quartz vibrator via the via hole 22 and the internal terminals 19 and 18. Connected to piece 14. If necessary, a part of the wiring pattern 30 may be replaced with a circuit 33 inside the base 11.
Is connected to the external terminal 20 on the bottom surface of the base 11.

The embodiment shown in FIG. 4 is a composite piezoelectric vibrator having two piezoelectric vibrators, in which an AT-cut quartz vibrating piece 34 is mounted on the bottom surface of the space of the base 11. A pair of connection terminals 35 are formed on the bottom surface of the cavity, and an AT-cut quartz-crystal vibrating piece 34 is fixed on the base end 34a in a cantilever manner with a conductive adhesive 36 at the base end 34a. 14 is held substantially horizontally below. The connection terminal 35 is drawn out to the outer surface of the base 11 and connected to the corresponding external electrode 21, so that the AT-cut crystal vibrating piece 34 conducts to the external electrode 21. In this embodiment, the crystal vibrating piece 34
The base end portion 34a and the front end portion 34b of the tuning fork type quartz vibrating piece 14 are arranged on opposite sides of the base end portion 14a and the front end portion 14b, respectively. Thereby, even if the tip portion of each crystal vibrating piece vibrates or vibrates largely due to an impact due to a drop or an external mechanical vibration, there is little risk of collision and breakage with each other, and the impact resistance is improved. preferable.

In the manufacturing process of the composite piezoelectric vibrator of the present embodiment, the oscillation frequency of the AT-cut crystal vibrating piece 34 is roughly adjusted to a predetermined frequency range when mounted on the base 11. Next, the lid 12 is joined to the base 11 and integrated,
In addition, a conductive adhesive 24 is applied to make the internal terminals 18 of the lid and the internal terminals 19 of the base conductive. This package is placed in a vacuum atmosphere, and the metal ball 27 placed on the step 25 'of the sealing hole 25 is welded by a laser beam as described above, so that the sealing hole is closed with a sealing material 26. Then, the package 13 is vacuum-sealed.

In this state, the oscillation frequency of the AT-cut quartz-crystal vibrating piece 34 is finely adjusted. This is because, while measuring the frequency through the external electrode 21, the laser beam 28 ′ is applied from the outside of the transparent lid 12 through the gap between the two vibrating arms of the tuning-fork type quartz vibrating piece 14 to the surface of the AT-cut quartz vibrating piece 34. This is performed by irradiating the excitation electrode and partially removing it. Further, in this state, the oscillation frequency of the tuning-fork type quartz vibrating piece 14 is finely adjusted. This measures the frequency through the internal terminal 18 or the external electrode 20 similarly exposed on the outer surface of the lid 12,
A laser beam 28 is radiated from the outside through the transparent lid 12, and the tip portion 14b of each vibrating arm of the tuning-fork type quartz vibrating piece 14
This is performed by partially removing the metal weight in the frequency adjustment region provided in. The order in which the respective resonator elements are irradiated with a laser beam to adjust the frequency may be reversed.

In another embodiment, the AT-cut quartz vibrating piece 3
The frequency fine adjustment of 4 can be performed before closing the sealing hole 25 with the sealing material 26. This is because, after the lid 12 is bonded to the base 11, the frequency of the excitation electrode is similarly measured via the external electrode 21, and the excitation electrode on the surface of the AT-cut quartz vibrating piece 34 is ion-etched through the sealing hole 25. Is partially removed. In this case, fine tuning of the frequency of the tuning-fork type quartz vibrating piece 14 may be performed by closing the sealing hole 25 with the sealing material 26 and then irradiating the laser beam 28 from outside the lid 12 in the same manner. .

In this embodiment, by arranging two crystal vibrating pieces of different types and different frequency bands on the upper and lower sides as described above, it is possible to reduce the size and thickness of the package and to obtain a composite type crystal vibrator. Can be realized. In addition, the two quartz vibrating pieces are separately mounted on the base and the lid, and after roughly adjusting the frequency, the base and the lid are joined together to assemble the package, thereby improving work efficiency and productivity. If there is a defect in the crystal vibrating piece, only one of the pieces needs to be discarded, so that the manufacturing yield can be improved and the manufacturing cost can be reduced.
Further, since the frequency of both quartz-crystal vibrating pieces can be finely adjusted after the package is vacuum-sealed, a higher quality and higher stability composite vibrator can be obtained.

In particular, in the present embodiment, since the two piezoelectric vibrating reeds 14, 34 are accommodated in the miniaturized and thinned package 13 as described above, the internal volume is much larger than in the prior art. Has become smaller. For this reason, a gas generated from a conductive adhesive for fixing the piezoelectric vibrating pieces or a gas generated when the lid 12 is bonded to the base 11 with the low-melting glass or expanded by the heat is generated inside the package. The effect on the degree of vacuum, and therefore on the CI value of the piezoelectric vibrator, is greater. In the package 13 of the present embodiment, the gas generated inside the package 13 and the expansion thereof can be released from the sealing hole 27 before the sealing, so that a higher degree of vacuum is secured.
A lower CI value can be ensured.

In the composite piezoelectric vibrator of the present invention, the lid 12
The piezoelectric vibrating reed mounted on the base 11 is not limited to the combination of the tuning-fork type quartz vibrating reed 14 and the AT-cut quartz vibrating reed 34 of the above embodiment. For example, lid 1
A tuning fork type crystal vibrating piece having a different oscillation frequency can be mounted on each of the base 2 and the base 11. Such a composite piezoelectric vibrator is particularly suitable for a multi-channel type application that operates at different frequencies in a region or country where it is used, such as a radio-controlled timepiece. In this case, it is preferable that the double tuning-fork type quartz vibrating reeds are arranged so that the metal weight material provided at the tip of each vibrating arm can be individually irradiated with a laser beam from outside the lid 12. Therefore, unlike the above embodiments,
It is also possible to arrange the base ends of the respective piezoelectric vibrating reeds in the package on the same side in the longitudinal direction, or to arrange the two piezoelectric vibrating reeds so that they do not overlap each other in a plane.

Also, contrary to the above embodiment, a tuning fork type crystal vibrating piece can be mounted on the base 11 and an AT cut crystal vibrating piece can be mounted on the lid 12. In this case, similarly, the frequency of each crystal resonator element can be finely adjusted by irradiating a laser beam from outside the lid 12. Further, an AT-cut quartz-crystal vibrating piece can be mounted on each of the base 11 and the lid 12.

FIG. 5 schematically shows the inner surface of the lid 12 of the crystal unit according to the second embodiment of the present invention. The recess 15 on the inner surface of the lid 12 in this embodiment has a peripheral portion defining a narrow gap therebetween along the outer peripheral edge of the base end portion around the base end portion 14a of the tuning-fork type quartz vibrating piece 14. Is provided in the vicinity. Thus, when the tuning-fork type quartz vibrating piece 14 is arranged in the recess 15 of the lid 12, the positioning thereof can be simplified.

Conductive adhesive 1 attached to connection terminal 16
Reference numeral 7 fills a gap between the base end portion and the peripheral edge of the recess 15 when the base end portion 14a of the quartz-crystal vibrating piece is placed and fixed thereon. Therefore, even if the amount of the conductive adhesive 17 used is relatively small, the base end portion 14a of the quartz vibrating reed is not only between the back surface and the upper surface of the connection terminal 16 but also the outer peripheral edge and the recess 1.
Since it is fixed between the five peripheral portions, the mounting strength is increased. Therefore, the tuning-fork type quartz vibrating piece 14 can be fixed sufficiently firmly and more stably.

On the other hand, the concave portion 15 on the inner surface of the lid 12 is provided so that the peripheral portion is separated from the vibrating arms by a sufficient distance around the vibrating arms which are the vibrating portions of the tuning-fork type quartz vibrating piece 14. Can be Accordingly, even if both vibrating arms of the tuning-fork type quartz vibrating piece 14 vibrate greatly left and right during oscillation of the quartz oscillator, there is no possibility that the vibration may be hindered by touching the peripheral edge of the recess 15 and stable and favorable. Performance is obtained.

FIGS. 6A and 6B show a modification of the second embodiment. In this modification, a plurality of small concave portions are formed along the outer periphery of the base end portion 14a of the tuning-fork type quartz vibrating piece 14. On each side of the base end portion 14a, one first concave portion 37 formed of a U-shaped notch is formed at a position near the vibrating arm. For this reason, the proximal end 1
Unless an excessive amount is used, the conductive adhesive 17 flowing to the vibrating arm side along each side of 4a accumulates in the first concave portion 37 and does not flow to the vibrating arm side any more. Therefore, it is possible to eliminate in advance the possibility that the conductive adhesive 17 unnecessarily wraps around the vibrating arm side and solidifies, thereby lowering the mount strength or affecting the vibration of the tuning-fork type quartz vibrating piece 14. The first concave portion 37 can have various shapes other than the U-shape of the present embodiment.

On the edge of the base end portion 14a, two second concave portions 38, each also formed of a U-shaped notch, are provided with the convex portion 3 therebetween.
9 are sandwiched therebetween. The second concave portion 38 is disposed between a pair of extraction electrodes 40 provided on both right and left ends of the base end portion 14a, and a conductive adhesive flowing along the extraction electrodes 40 from the both ends along the end side. Unless an excessive amount is used, 17 enters and accumulates in the second concave portion 38 and does not flow to the extraction electrode 40 on the opposite side any more. Therefore, even if the separation distance between the extraction electrodes 40 is reduced due to the downsizing of the tuning-fork type quartz vibrating piece 14, a short circuit between the both extraction electrodes due to the conductive adhesive can be effectively prevented. Similarly, the second concave portion 38 can have various shapes other than the U-shape of the present embodiment.

The corners 41 of the base end 14a are rounded to the same extent as the corners of the adjacent recess 15. Therefore, the conductive adhesive 17 easily wraps around each corner 41, and as shown by the imaginary line 42 in FIG. Adhere to cover. Therefore, the tuning-fork type quartz vibrating piece 14
Is more firmly fixed at the corners of the base end 14a, and its mounting strength is improved. Further, when the tuning fork type quartz vibrating piece 14 is arranged in the recess 15 of the lid 12, more accurate positioning can be simplified.

Further, the tuning-fork type quartz vibrating piece 14 of this embodiment is used.
Are the fixed portion of the base end portion 14a to the lid 12 and the vibrating arm 14b
The vibration of each vibrating arm 14b is blocked by the first concave portion 37 and does not reach the fixed portion of the base end portion 14a. For this reason, each vibrating arm 14b can bend more freely, and therefore the CI value can be suppressed lower. However, in the case where air or other gas is present in the package 13 or the degree of vacuum is low, the first concave portion becomes more airy as the internal volume of the package 13 becomes smaller, particularly in accordance with the miniaturization of the crystal unit. In order to receive the resistance, the crystal vibrating piece 14
Is likely to be restricted, and the CI value may not be lowered as expected. In the tuning fork type crystal resonator of the present embodiment, the package 13 has the sealing structure described above with reference to FIG. Can be sealed to a high degree of vacuum, so that a more flexible bending motion of the vibrating arm can be secured, and downsizing and a sufficient decrease in the CI value can be realized at the same time.

FIGS. 7A and 7B schematically show a crystal resonator according to a third embodiment of the present invention. In this embodiment, a ridge 43 is formed on the inner surface of the lid 12 so as to form a stepped portion along the inner periphery of the joint surface 12a with the base 11 shown by hatching in FIG. And is provided between them. When the lid 12 is joined to the base 11, the positioning can be performed accurately and easily without particularly using a separate positioning means, by aligning the step portion with the upper end surface, that is, the inner peripheral edge of the joining surface. it can.

FIGS. 8A and 8B schematically show a crystal resonator according to a third embodiment of the present invention. In this embodiment, the tip 1 of the tuning-fork type quartz vibrating piece 14 on the inner surface of the lid 12 is used.
A second recess 44 is formed in a region adjacent to 4b. Accordingly, even if the tip portion 14b of the tuning-fork type quartz vibrating piece 14 swings or vibrates largely due to a shock due to a drop or external mechanical vibration, the risk of colliding with the inner surface of the lid 12 and being damaged is reduced. Therefore, the impact resistance is greatly improved. The second recess 44 is formed by, for example, etching or by an integral molding method such as stamping of a glass material.
5 can be processed simultaneously.

FIG. 9 shows the first embodiment of the present invention shown in FIGS.
9 schematically shows a modification of the embodiment. The tuning-fork type quartz vibrator of this embodiment is characterized by the structure of the tuning-fork type quartz vibrating piece in addition to the package 13 having the configuration shown in FIG. FIG.
1A, a tuning-fork type quartz vibrating piece 14 mounted on a lid 12 has a structure as described in, for example, JP-A-56-65517, and extends in parallel from a base end 14a. Grooves 47a, 47b are formed in the upper and lower main surfaces 46a, 46b of the pair of vibrating arms 14b in a straight line along the longitudinal direction, respectively. Each groove 47a of the vibrating arm 14b,
As shown in FIGS. 9B and 9C, a first electrode 48 made of an electrode film formed on the side surface and the bottom surface is provided on 47b.
a, 48b are provided, and second electrodes 49a, 49b formed on each side surface of the vibrating arm 14b are provided, and the first electrode 48a (48b) of one vibrating arm is connected to the second electrode of the other vibrating arm. A drive electrode that is electrically connected to 49b (49a) and vibrates the tuning-fork type quartz vibrating piece 14 is configured. The extraction electrodes 40a and 40b from the drive electrodes are connected to the corresponding connection terminals 1 on the inner surface of the lid 12 at the base end 14a.
6 and 16 are fixed with conductive adhesives 17 and 17.

In the tuning-fork type quartz vibrating piece having such a structure, when an AC voltage is applied from the connection terminals 16 to the drive electrodes, the adjacent first electrodes 48a and 48b and the second electrodes 48a and 48b
As shown in FIG. 9C, electric fields E1 and E2 parallel to the respective main surfaces are generated between the electrodes 49a and 49b. As a result, the electric field efficiency is greatly improved and the CI value is suppressed to be low. Can be. However, if air or other gas is present in the package 13 or the degree of vacuum is low, the vibrating arm 14b that performs a bending motion in a plane including the main surface thereof receives air resistance in the grooves 47a and 47b, and therefore, in particular, As the internal volume of the package 13 decreases as the crystal unit is reduced in size, the bending motion is more likely to be restricted, and the CI value may not be suppressed as low as expected. In this embodiment, since the package 13 has the sealing structure described above with reference to FIG. 1, gas generated from low-melting glass, a conductive adhesive, or the like is suppressed,
The inside of the package can be sealed to a high degree of vacuum. Therefore, the crystal unit of the present embodiment can achieve both miniaturization and a sufficient decrease in the CI value at the same time.

FIG. 10 schematically shows another modification of the first embodiment in which the quartz oscillator of FIG. 9 is further modified.
In FIG. 10A, the tuning-fork type quartz vibrating reed 14 mounted on the lid 12 has a base end 14a and a portion fixed to the lid 12 and a vibrating arm 14b, similarly to the embodiment of FIG. A U-shaped notch formed therebetween, that is, a constricted portion 45 formed by the first concave portion 37 is provided. Since the vibration of each vibrating arm 14b is interrupted by the first concave portion 37 and does not reach the fixed portion of the base end portion 14a, the vibrating arms 14b can bend more freely, and thus the CI value can be suppressed lower. Further, the constricted portion 45 is formed with the first concave portion 3 having various shapes other than the U-shape.
7 or various recesses provided on the side of the base end 15a.

However, in the case where air or other gas is present in the package 13 or the degree of vacuum is low, the smaller the internal volume of the package 13 is, the smaller the size of the crystal unit is, the more the first concave portion becomes. Because of the extra air resistance, the bending motion of the quartz vibrating reed 14 is rather limited,
There is a possibility that the CI value cannot be lowered as expected. In the tuning fork type crystal resonator of the present embodiment, similarly, the package 13 has the sealing structure described above with reference to FIG.
Since the inside of the package can be sealed to a high degree of vacuum, a free bending motion of the vibrating arm is secured, and downsizing and a sufficient decrease in the CI value can be realized at the same time.

Although the preferred embodiments of the present invention have been described in detail above, as will be apparent to those skilled in the art, the present invention is implemented by adding various changes and modifications to the above embodiments within the technical scope thereof. be able to. For example, an AT-cut quartz-crystal vibrating piece may be mounted on the lid 12 of each of the above-described embodiments instead of the tuning-fork-type quartz-crystal vibrating piece. It can be performed. The embodiments described above can be implemented in combination with each other. For example, the configuration of the lid 12 and / or the vibrating bar base end portion 14a as in the embodiment of FIGS. 5 and 6 can be applied to each of the other embodiments, and the lid structure of each of the above embodiments. Can be configured as shown in FIG. 7 or FIG. Further, in the embodiment of FIG. 3, an additional piezoelectric vibrating reed can be mounted on the lid 12 or the base 11. Further, the tuning-fork type quartz vibrating piece of FIG. 9 or FIG. 10 can be applied to other embodiments.

[0058]

According to the piezoelectric device of the present invention, the package can be made thinner by the above-described structure, and the possibility of damaging the piezoelectric vibrating reed by the contact of a jig or the like when joining the lid to the base is reduced. The assembly work is easy and the yield is improved, and various electronic components such as an IC circuit, a capacitor, and a resistor, which are oscillation circuits of a piezoelectric vibrating piece, are mounted on a base, or different oscillation frequencies, different or the same type. By further mounting the piezoelectric vibrating piece of the present invention, it is possible to realize a piezoelectric device such as a small and thin piezoelectric oscillator, a composite vibrator or the like.

In particular, by adopting a structure in which a sealing hole is provided in the base of the package and hermetically sealed with a sealing material, low melting point glass or the like is used when each piezoelectric vibrating piece is mounted or when the package is sealed. Since the gas generated from the conductive adhesive or the like can be suppressed and a higher degree of vacuum can be sealed, the frequency of the quartz vibrating piece mounted in this package can be adjusted with higher precision after vacuum sealing. Furthermore, by combining one drive electrode on the side surface of the groove provided on the main surface of the vibrating arm, or by providing a constricted portion at the base end, it is possible to simultaneously reduce the size of the piezoelectric device and suppress the CI value. Realized,
Higher quality and higher stability than before can be achieved.

[Brief description of the drawings]

1A is a plan view showing a crystal unit according to a first embodiment of the present invention, FIG. 1B is a longitudinal sectional view thereof, and FIG. 1C is a bottom view thereof.

FIG. 2 is a bottom view of the lid of the first embodiment shown in FIG.

FIG. 3 is a longitudinal sectional view of a crystal oscillator which is a modification of the first embodiment.

FIG. 4 is a longitudinal sectional view of a composite quartz-crystal vibrator as a modification of the first embodiment.

FIG. 5 is a bottom view of a lid according to a second embodiment of the present invention.

FIG. 6A is a bottom view of a lid according to a modification of the second embodiment, and FIG. 6B is a partially enlarged view thereof.

FIG. 7A is a longitudinal sectional view of a quartz oscillator according to a third embodiment of the present invention, and FIG. 7B is a bottom view of a lid.

FIG. 8A is a longitudinal sectional view of a quartz oscillator according to a fourth embodiment of the present invention, and FIG. 8B is a bottom view of a lid.

FIG. 9A is a bottom view of a lid of a quartz resonator according to a modification of the first embodiment, FIG. B is a partially enlarged view of FIG. A showing its vibrating arm, and FIG. It is an expanded sectional view of a vibrating arm.

FIG. 10A is a plan view of a lid further showing a modification of FIG. 9;
FIG. B is a partially enlarged view of the base end portion.

FIG. 11 is a longitudinal sectional view showing a conventional piezoelectric vibrator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 13 Package 2, 11 Base 3, 12 Lid 4 Piezoelectric vibrating reed 12a Joining surface 14 Tuning fork type quartz vibrating reed 14a Base end 14b Tip 15 recess 16 Connection terminal 17 Conductive adhesive 18, 19 Internal terminal 20, Reference Signs List 21 external electrode 22 via hole 23 wiring circuit 24 conductive adhesive 25 sealing hole 25 'step 26 sealing material 27 metal ball 28 laser beam 29 IC chip 30 wiring pattern 31 bonding wire 32, 33 wiring circuit 34 AT-cut quartz vibrating piece 34a Base end portion 34b Tip end portion 35 Connection terminal 36 Conductive adhesive 37 First concave portion 38 Second concave portion 39 Convex portion 40, 40a, 40b Extraction electrode 41 Corner portion 42 Imaginary line 43 Ridge 44 Second concave portion 45 Neck Part 46a, 46b Main surface 47a, 47b Groove 48a, 48b First electrode 49a 49b the second electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H03H 9/215 H03H 9/215 F term (Reference) 5J079 AA04 BA43 BA44 HA03 HA05 HA07 HA09 HA28 HA29 5J108 AA02 BB02 CC04 CC06 CC08 DD02 DD05 EE03 EE07 EE18 GG03 GG13 GG16 GG17 GG20 JJ01 JJ02 JJ04 MM01 MM04 NA02 NA03 NB05

Claims (18)

[Claims] 1. A package having a box-shaped base made of an insulating material and a thin plate-shaped lid made of a glass material joined to an upper surface of the base, and a piezoelectric vibrating piece hermetically sealed in the package. A piezoelectric device, wherein the lid has a recess on its inner surface, and the piezoelectric vibrating reed is mounted in the recess. 2. The method according to claim 1, wherein the base has a sealing hole at the bottom thereof for communicating the inside and the outside of the package, and the sealing hole is closed by a sealing material from the outside. The piezoelectric device according to claim 1. 3. The base has terminals on a joint surface with the lid, the lid has terminals on a joint surface with the base,
The piezoelectric device according to claim 1, wherein the terminal on the base side and the terminal on the lid side are electrically connected. 4. The terminal on the base side and the terminal on the lid side are electrically connected by a conductive adhesive, and at least the outside thereof is covered with a cushioning material.
6. The piezoelectric device according to claim 1. 5. The piezoelectric device according to claim 1, further comprising an electronic component mounted on the base. 6. The piezoelectric device according to claim 5, wherein the electronic component is an oscillation circuit of the piezoelectric vibrating reed. 7. The piezoelectric vibrating reed is supported in a cantilever manner at a base end thereof by a conductive adhesive in the recess, and a peripheral edge of the recess is formed along a base end of the piezoelectric vibrating reed. The piezoelectric device according to claim 1, wherein the piezoelectric device is provided in close proximity to the device. 8. The piezoelectric device according to claim 7, wherein a concave portion is formed at an outer peripheral edge of the base end portion of the piezoelectric vibrating reed. 9. The piezoelectric device according to claim 8, wherein at least two of the concave portions are formed between a pair of extraction electrodes provided at the base end of the piezoelectric vibrating piece. 10. The piezoelectric device according to claim 7, wherein the corner of the base end of the piezoelectric vibrating reed and the corner of the recess adjacent thereto are rounded to the same extent. . 11. The device according to claim 1, wherein a second recess is formed in a region of the recess of the lid corresponding to a tip of the piezoelectric vibrating reed. Piezo device. 12. The piezoelectric device according to claim 1, wherein the lid has a step portion provided along an inner periphery of a joint surface with the base. 13. The piezoelectric device according to claim 1, wherein the piezoelectric vibrating reed is a tuning-fork type piezoelectric vibrating reed. 14. The apparatus according to claim 1, further comprising a second piezoelectric vibrating reed mounted on said base.
The piezoelectric device according to any one of the above. 15. The two piezoelectric vibrating reeds are cantilevered at a base end thereof, and are disposed such that the base end and the front end are located on opposite sides of each other. 15. The piezoelectric device according to 14. 16. The piezoelectric device according to claim 1, wherein the second piezoelectric vibrating reed is a tuning fork type piezoelectric vibrating reed. 17. The tuning-fork type piezoelectric vibrating reed has a drive electrode including a first electrode formed on each main surface of the vibrating arm and a second electrode formed on each side surface of the vibrating arm. 1
17. The piezoelectric device according to claim 13, wherein the electrode is formed of an electrode film formed on a side surface of a groove provided on at least one main surface of each of the vibrating arms along a longitudinal direction thereof. 18. The tuning-fork type piezoelectric vibrating reed has a constricted portion provided at the base end thereof between the portion fixed to the base or the lid and the vibrating arm. 18. The piezoelectric device according to item 17.