JP2002319839A - Piezoelectric device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric device such as a composite piezoelectric vibrator/ composite oscillator comprising a plurality of piezoelectric vibration chips each at a different oscillating frequency and of a different or the same type contained in a single package that is subjected to downsizing/low profile processing so as to attain fine frequency adjustment after package sealing and so as to be sealed at a high vacuum with high quality and stability. SOLUTION: The composite piezoelectric vibrator is provided with a rectangular box shaped package 13 comprising a base 11 formed by laminating ceramics thin plates and a glass thin plate cover 12. The cover on the inner face of which a tuning type quartz vibration chip 15 is mounted is bonded to an upper face of the base on which an AT-cut quartz vibration chip 14 is mounted. Inner terminals 20, 21 of the tuning type quartz vibration chip 15 air-tightly sealed and provided to the bonding face of the cover and the base are connected by a conductive adhesive 26 and conducted to an external terminal 22 on the base bottom face. An IC chip 38 is mounted on the base. A laser beam is used to fine-adjust the frequency of each quartz vibration chip from the outside of the cover. A sealing hole 27 made to the base bottom face is air-tightly sealed by a seal member 28 under a vacuum atmosphere after the bonding of the cover.

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, as shown in FIG. 11, a piezoelectric device equipped with a tuning fork type piezoelectric vibrating piece uses a transparent thin glass plate for a lid 3 joined to a base 2 of a package 1 and irradiates a laser beam from the outside after sealing. By partially removing the electrode film attached to the surface of the piezoelectric vibrating reed 4, the frequency can be adjusted with high accuracy.

[0004] Also, JP-A-2000-59169 discloses that
In order to achieve high-density mounting of motherboards and space saving in electronic devices such as computers using multiple types of crystal units, multiple press-fit sealed piezoelectric units are arranged in parallel and integrally molded. A sealed piezoelectric transducer array is disclosed. 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]

Recently, particularly in the field of communication technology, it is required to mount a plurality of oscillators having different oscillation frequency bands on one electronic device. Also, radio clocks, which have been rapidly spreading recently, have a function to automatically correct the time by receiving the standard time radio wave, but in order to receive radio waves of different frequencies in the region / country used,
A multi-channel type provided with a plurality of crystal units having different oscillation frequencies is desirable. In order to further reduce the size of these electronic devices, a piezoelectric device such as a composite vibrator or a composite oscillator in which a plurality of piezoelectric vibrators are housed in one package is required. However, in the conventional structure described in JP-A-2000-59169 described above,
Since a press-fit sealed type piezoelectric vibrator in which a piezoelectric vibrating piece is air-tightly sealed is integrated in each package, the size of the entire piezoelectric device is correspondingly increased, and there is a limit to miniaturization.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and has as its object to mount a plurality of piezoelectric vibrating reeds in a single package and reduce the size and thickness thereof. It is an object of the present invention to provide a surface-mount type piezoelectric device which can perform the following. Further, an object of the present invention is to provide a piezoelectric device which can adjust the frequency of each piezoelectric vibrating piece with high precision, can seal the inside of the package in a high-level vacuum or gas atmosphere, and has higher quality and excellent stability. It is in.

[0007]

According to the present invention, there is provided a package having a base made of an insulating material and a lid made of a glass material joined to an upper surface of the base. A first piezoelectric vibrating reed mounted on the base; and a second piezoelectric vibrating reed mounted on the base, wherein the first and second piezoelectric vibrating reeds are hermetically sealed in a package. A piezoelectric device is provided.

With this configuration, a plurality of piezoelectric vibrating pieces of different oscillation frequencies and different types can be hermetically sealed in a single package as required, and the package can be reduced in size and thickness. And a piezoelectric device such as a composite oscillator having an IC element mounted thereon.

In one embodiment, the first and second piezoelectric vibrating reeds are cantilevered at their base ends by a lid and a base, respectively, and the base ends of the first and second piezoelectric vibrating reeds are provided. The part and the tip are arranged on opposite sides of each other. Thereby, the wiring for connecting the external terminals provided on the outer surface of the package and the connection terminals of the respective piezoelectric vibrating reeds respectively formed on the base and the lid can be designed more freely, for example, the line length can be designed to be the shortest. .

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 base-side terminal and the lid-side terminal are electrically connected. It is connected. Thereby, the wiring circuit on the base side and the wiring circuit on the lid side can be connected, so that the wiring of the entire package is connected, for example, by connecting the first and / or second piezoelectric vibrating reeds to a common external terminal on the outer surface of the package. Can be designed freely.

In this case, the terminal on the base side and the terminal on the lid side can be electrically connected using a conductive adhesive.
Furthermore, if at least the outside is covered with a buffer, 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 during assembly, and the electrical connection may be lost. Is preferred since the amount of

The base and lid constituting the package can be used in various combinations. In one embodiment, the base has a rectangular box shape and the lid has a rectangular thin plate shape. Can be In particular, when the base has a laminated structure of ceramic thin plates, it is easy to provide the terminal on the base side on the joint surface with the lid or to form the internal wiring.

In another embodiment, the lid has a concave portion on its inner surface, and the first piezoelectric vibrating piece is accommodated in the concave portion so that a jig or the like may be touched when the lid is joined to the base. This is preferable because the risk of damaging the first piezoelectric vibrating piece is reduced.

In still another embodiment, the base is in the shape of a rectangular box, and the lid has a recess on its inner surface, and a first recess is formed in the recess.
Are accommodated. Thereby, the first and second piezoelectric vibrating reeds are respectively housed in the recesses of the lid or the base,
This is preferable because the risk of damaging each piezoelectric vibrating reed due to contact of a jig or the like at the time of joining the lid and the base is reduced.

In another embodiment, 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. After the lid is joined to the base, the package is placed in a predetermined gas atmosphere such as vacuum or nitrogen to close the sealing hole, and the inside of the package is hermetically sealed to a higher vacuum or gas atmosphere. be able to. If the second piezoelectric vibrating reed is an AT-cut quartz vibrating reed, the frequency can be finely adjusted by performing ion beam etching through a sealing hole after sealing the package.

When the first piezoelectric vibrating reed is a tuning fork type piezoelectric vibrating reed, a laser beam is irradiated from outside of the package through a glass lid after the package is sealed, so that the first vibrating reed is attached to the vibrating reed. The fine adjustment of the frequency can be easily performed by removing the metal weight.

In this case, it is preferable that the second piezoelectric vibrating reed is disposed at a position displaced from below a frequency adjustment region provided at the tip of the tuning fork type piezoelectric vibrating reed, and the metal weight material blown by the laser beam is preferably used. Adheres to the second piezoelectric vibrating reed,
It is possible to prevent adverse effects, such as deviating the frequency.

In another embodiment, the second piezoelectric vibrating reed may be a tuning fork type piezoelectric vibrating reed. In this case, in particular, if 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, the oscillation also depends on the use conditions such as the use area such as a radio clock. Even when a multi-channel type having a different frequency is required, it can be easily handled.

In one embodiment, at least one of the first and second piezoelectric vibrating pieces is a tuning-fork type piezoelectric vibrating piece,
The tuning-fork type piezoelectric vibrating reed has a drive electrode composed of 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, and the first electrode is provided with each of the vibrating arms. It is formed of an electrode film formed on a side surface of a groove provided on at least one main surface of the arm along the longitudinal direction.

A tuning-fork type piezoelectric vibrating reed having such a grooved vibrating arm structure is known, as described in, for example, Japanese Patent Application Laid-Open No. 56-65517, and applies an electric field parallel to the main surface of the vibrating arm. It is known that the generation can greatly increase the electric field efficiency, thereby suppressing the CI (crystal impedance) value 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 a bending motion, the extra air resistance received by the groove provided on the main surface of the vibrating arm is not sufficient. Therefore, as the tuning fork type piezoelectric vibrating reed is miniaturized and miniaturized with the miniaturization and miniaturization of the piezoelectric device, the bending motion of the vibrating arm is more restricted, so that the expected CI value is lowered. It may not be possible. The piezoelectric device of the present invention,
The inside of the package can be sealed to a high degree of vacuum by closing the sealing hole provided at the bottom of the base with the sealing material from the outside after joining the lid to the base. As a result, a sufficient decrease in the CI value can be obtained.

In still another embodiment, at least one of the first and second piezoelectric vibrating reeds is a tuning fork type piezoelectric vibrating reed, and the tuning fork type piezoelectric vibrating reed is fixed to a base or a lid at a base end thereof. It has a constricted portion provided between the portion and the vibrating arm.

In this tuning-fork type piezoelectric vibrating reed, since the vibration of the vibrating arm is interrupted by the constricted portion and does not reach the fixed portion of the base end portion, the vibrating arm can bend more freely.
The I value is suppressed lower. However, the bending motion of the vibrating arm causes extra air resistance in the constricted part when gas such as air exists in the package or when a sufficient degree of vacuum cannot be obtained. As the tuning fork type piezoelectric vibrating reed becomes smaller and smaller with the development of the piezoelectric element, the bending motion of the vibrating arm is restricted.
There is a possibility that a decrease in the value cannot be obtained. In the piezoelectric device of the present invention, the inside of the package can be sealed to a high degree of vacuum by closing the sealing hole similarly provided in the bottom of the base with the sealing material from the outside after the lid is joined. It is possible to secure a more flexible bending motion and obtain a sufficient decrease in the CI value.

[0023]

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. 1A to 1C schematically show a configuration of a composite piezoelectric vibrator which is a first embodiment of a piezoelectric device to which the present invention is applied. This composite piezoelectric vibrator includes a package 13 having a rectangular box-shaped base 11 and a thin plate-shaped lid 12.
And two quartz-crystal vibrating pieces 14 and 15 are hermetically sealed therein. The lid 12 is air-tightly joined to the upper end surface of the base 11 with a low-melting glass as in the related art. In this embodiment, an AT-cut crystal vibrating piece and a tuning-fork type quartz vibrating piece in different frequency bands are appropriately selected as the crystal vibrating piece according to the application.

The base 11 is formed in a substantially rectangular box shape by laminating a plurality of ceramic thin plates. A connection terminal 16 is formed at the bottom of the space defined inside the base 11, and an AT-cut quartz-crystal vibrating piece 14 is provided thereon with a conductive adhesive 17 at its base end 14 a in a cantilever manner. And it is fixed substantially horizontally.

The lid 12 is formed of a rectangular thin plate made of a transparent glass material, and has connection terminals 18 formed on the inner surface thereof.
A tuning-fork type quartz vibrating piece 15 is fixed on the base end 15a thereof in a cantilever manner and substantially horizontally with a conductive adhesive 19 thereon. The two quartz-crystal vibrating pieces are arranged such that the base end and the front end are located on opposite sides. At two corners of the lid 12 on the side of the vibrating bar base end 15a, internal terminals 20 for wiring are drawn out from the connection terminals 18 over both front and back surfaces. These terminals are formed, for example, by vapor deposition or sputtering of a metal wiring material, or by etching a formed metal wiring material.
In addition, such a lid can pattern the terminals by etching a thin glass plate having an electrode film formed on the surface, thereby obtaining good dimensional accuracy and positional accuracy.

On the upper end surface of the base 11, internal terminals 21 for wiring are provided at two corners corresponding to the internal terminals 20, respectively. Further, on the bottom surface of the base 11, external electrodes 22 and 23 are provided at each corner. Each of the internal terminals 21 on the upper end surface of the base is formed with a via hole 24 formed immediately below the terminal.
And the base end 15 of the same vibrating reed via the wiring pattern 25.
Each is connected to the external electrode 22 on the a side.

The internal terminal 20 of the corresponding lid and the internal terminal 21 of the base are electrically connected by, for example, a conductive adhesive 26, so that the tuning-fork type quartz vibrating piece 15 is electrically connected to the external electrode 22. On the other hand, the connection terminal 1 of the base
Reference numerals 6 are respectively drawn out to the outer surface of the base and connected to the corresponding external electrodes 23, thereby making the AT-cut quartz-crystal vibrating piece 14 conductive to the external electrodes 23. The wirings and external electrodes of the base 11 are formed by screen-printing a metal wiring material such as W or Mo on the surface of the thin ceramic plate, baking it, and plating Ni and Au thereon.

Further, the base 11 is provided with a small-diameter circular sealing hole 27 penetrating through the center of the bottom surface, and is closed with a suitable sealing material 28. The sealing material 28 is filled by, for example, welding a metal ball 29 made of Au-Sn or the like placed on the step 27 'of the sealing hole with a laser beam or the like. By having such a structure, the composite piezoelectric vibrator of the present embodiment can realize high-precision frequency adjustment of each vibrating piece and a high degree of vacuum inside the package as described in detail below.

In the manufacturing process of the composite piezoelectric vibrator of this embodiment, each of the quartz vibrating pieces 14 and 15 is mounted on the base 11 and the lid 12 in a separate step, and the oscillation frequency is roughly adjusted to a predetermined frequency range. adjust. Next, the lid 12 is air-tightly bonded to the base 11 with low-melting glass to be integrated, and a conductive adhesive 26 is applied to make the internal terminals 20 of the lid and the internal terminals 21 of the base conductive. Next, the package is placed in a vacuum atmosphere, and the sealing holes 2 are formed as described above.
By welding the Au-Sn ball placed on the step 27 'of FIG. 7 with a laser beam, the sealing hole 27 is closed with a sealing material 28, and the package 13 is vacuum-sealed.

In this state, the oscillation frequency of the AT-cut quartz-crystal vibrating piece 14 is finely adjusted. This is because the laser beam 30 is applied from outside the transparent lid 12 to the AT-cut quartz vibrating piece 14 through the gap 15c between the vibrating arms of the tuning fork-type quartz vibrating piece 15 while measuring the frequency through the external electrode 23. This is performed by irradiating the excitation electrode on the surface and partially removing it. Further, in this state, the oscillation frequency of the tuning-fork type quartz vibrating piece 15 is finely adjusted. This is done by measuring the frequency via the internal terminals 20 or the external electrodes 22 exposed on the outer surface of the lid 12, and from the outside through the transparent lid 12, as well as the laser beam 3.
This is performed by irradiating 0 ′ to partially remove the metal weight in the frequency adjustment region provided at the tip portion 15b of each vibrating arm of the tuning-fork type quartz vibrating piece 15. Note that the order in which the respective resonator elements are irradiated with the laser beam to adjust the frequency may be reversed.

In another embodiment, the AT-cut quartz vibrating reed 1
The frequency fine adjustment of 4 can be performed before closing the sealing hole 27 with the sealing material 28. This is because, after the lid 12 is joined to the base 11, the frequency of the excitation electrode is similarly measured via the external electrode 23, and the excitation electrode on the surface of the AT-cut quartz vibrating piece 14 is ion-beam etched through the sealing hole 27. Is partially removed. Fine tuning of the frequency of the tuning-fork type quartz vibrating piece 15 may be performed by closing the sealing hole 27 with the sealing material 28 and then irradiating the laser beam 30 ′ from outside the lid 12.

In the present embodiment, the size and thickness of the package can be reduced by arranging the two crystal vibrating pieces vertically, and the two types of crystal vibrating pieces are separated in the assembly of the package. After being mounted on the base and lid and coarsely adjusting the frequency, the base and lid are joined to improve work efficiency and productivity. Since it is only necessary to discard only the composite piezoelectric vibrator, the production yield of the composite piezoelectric vibrator is improved, and the production 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 this embodiment, the two piezoelectric vibrating reeds 14 and 15 are accommodated inside the miniaturized and thinned package 13 as described above. 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.

FIG. 2 schematically shows a composite piezoelectric vibrator according to a modification of the first embodiment. In this modified example, elastic dampers 31 and 32 are provided at appropriate locations on the base ends 14a and 15a of the crystal vibrating pieces 14 and 15, respectively. As a result, even if the tip portions 14b and 15b of each of the quartz vibrating pieces swing or vibrate due to an impact due to a drop or external mechanical vibration, and even if they strike the base end portion of the other quartz vibrating piece, the impact is absorbed and Damage to the crystal vibrating piece can be prevented, and there is no fear of frequency fluctuation, so that the shock resistance is greatly improved. When the elastic material is formed, when the resin material is provided so as to cover the bonding portions of the base ends of the respective vibrating pieces with the conductive adhesives 17 and 19 as shown in FIG. It is preferable because it improves.

The elastic buffer portions 31 and 32 are formed of a known resin material such as a silicone-based / urethane-based adhesive which has elasticity after curing and more preferably has electrical insulation. In particular, a UV (ultraviolet) curable resin adhesive is preferable because it can be cured relatively easily and can be cured at a predetermined position in a desired form without affecting the quartz-crystal vibrating piece and the electrode film at all.

FIG. 3 shows a composite piezoelectric vibrator according to a modification of FIG. In this modification, a projection 33 is formed on the inner surface of the lid 12 at a position behind the base end 15a of the crystal vibrating piece 15 and at a position corresponding to the distal end portion 14b of the crystal vibrating piece 14. The protrusion 33 is formed by, for example, attaching low-melting glass to the inner surface of the lid 12. At the tip of the projection 33, an elastic buffering portion 34 is made of a known resin material or the like having elasticity and more preferably electrical insulation as in the embodiment of FIG.
It is provided higher than the crystal resonator element 15. Accordingly, even if the tip portion 14b of the AT-cut quartz-crystal vibrating piece 14 shakes or vibrates due to a shock due to a drop or external mechanical vibration, there is no possibility of colliding with the base end of the tuning-fork type quartz-crystal vibrating piece 15, and Even if it collides with the buffer portion 34, the shock can be absorbed to prevent breakage, there is no possibility of frequency fluctuation, and the shock resistance is greatly improved.

FIGS. 4A, 4B and 5A,
(B) shows a composite piezoelectric vibrator according to another modification of the first embodiment. In the modified examples of FIGS. 4A and 4B, elastic cushioning materials 35 are attached so as to wrap the joints with the base 11 at the four corners of the lid 12 from the outside. In particular, 2 on the side where the internal terminals 20 and 21 are provided.
The two corners are provided so as to completely cover the conductive adhesive 22 connecting them. In contrast, FIG.
In the modified examples of (A) and (B), the joint with the base 11 is wrapped from the outside along the entire periphery of the lid 12.
An elastic cushion 36 is attached.

In each case, the elastic cushioning materials 35, 36
As a result, the sealing strength of the package 13 is improved, and the force or impact applied to the package from the outside directly acts on the joint between the lid 12 and the base 11 to prevent the lid from being damaged or peeled off and opened. Can be. These elastic cushioning materials 35 and 36 are also similar to the elastic cushioning parts in the embodiment of FIGS. 2 and 3 and have a silicone-urethane adhesive having elasticity after curing and more preferably having electrical insulation. And other known resin materials.

FIG. 6 shows a composite piezoelectric vibrator according to still another modification of the first embodiment. In this embodiment, the AT-cut quartz vibrating piece 14 is provided below the tip portion 15b of each vibrating arm in which the frequency adjustment region of the tuning fork type quartz vibrating piece 15 is provided.
The two quartz-crystal vibrating reeds are arranged at positions slightly deviated from each other so as to prevent the existence of the above. More specifically, the base end portion 14a of the AT-cut quartz-crystal vibrating reed is slightly shifted toward the base end portion 15a side of the tuning-fork type quartz-crystal vibrating reed as compared with the embodiment of FIG. The partition 37 is provided by a thin ceramic plate constituting a part of the base 11. With this partition, the space inside the base is separated from the AT-cut quartz-crystal vibrating reed 14 in the lower region of each vibrating arm tip portion 15b.
At the time of the frequency fine adjustment of 5, it is possible to prevent the possibility that the metal material scattered from the tip portion 15b adheres to the AT-cut quartz-crystal vibrating piece and has a bad influence such as frequency fluctuation.

FIG. 7 schematically shows a piezoelectric oscillator according to a second embodiment of the present invention. In this piezoelectric oscillator, a recess 11a is further provided at the bottom of the cavity of the base 11 below the AT-cut quartz-crystal vibrating piece 14, and an IC chip 38 as an oscillation circuit is mounted therein by flip-chip bonding. This is different from the first embodiment in FIG. Further, the base 11 has an IC chip 3 at the bottom of the space.
A sealing hole 27 is formed at an appropriate position other than the mounting region 8 and closed with a sealing material 28. This realizes a composite piezoelectric oscillator corresponding to different frequency bands.

FIG. 8 shows a composite piezoelectric vibrator according to a third embodiment of the present invention. This piezoelectric vibrator has a base 11
Is made of a flat ceramic substrate, and AT
The cut quartz vibrating piece 14 is mounted, the lid 12 has a concave portion 12a formed on the inner surface of the sheet glass, and the tuning fork type quartz vibrating piece 15 is accommodated in the concave portion. 1 is different from the first embodiment. Thus, the recess 12
The crystal vibrating piece housed in a is easy to work because there is little possibility that a jig or a hand directly touches when the lid 12 is handled.
This is preferable because the yield is improved.

This recess is easily formed by etching the surface of a glass plate cut into a predetermined rectangular size, for example. Further, the lid 12 can be formed into a desired shape by an integral molding method such as a stamping process of a glass material.

The tuning-fork type quartz resonators shown in FIGS. 9 and 10 are characterized by the structure of the tuning-fork type quartz resonator element in addition to the package 13 shown in FIG. In FIG. 9, a tuning-fork type quartz vibrating piece 15 mounted on a lid 12 has a structure as described in, for example, Japanese Patent Application Laid-Open No. 56-65517, and extends in parallel from a base end 15a. Grooves 40a, 40b are formed in the upper and lower main surfaces 39a, 39b of the pair of vibrating arms 15b in a straight line along the longitudinal direction, respectively. As shown in FIGS. 9C and 9D, the grooves 40a and 40b of the vibrating arm 15b are provided with first electrodes 41a and 41b formed of electrode films formed on the side and bottom surfaces thereof, respectively. Second electrodes 42a and 42b formed on each side surface of the arm 15b are provided.
The electrode 41a (41b) is the second electrode 42b of the other vibrating arm.
(42a) is electrically connected to the tuning-fork type quartz vibrating reed 1
5 constitutes a drive electrode for vibrating the piezoelectric element 5. Extraction electrodes 43a and 43b from the drive electrodes are provided at the base end 15a, and are fixed to the corresponding connection terminals 18 and 18 provided on the inner surface of the lid 12 with conductive adhesives 19 and 19, respectively. Have been.

In the tuning-fork type quartz vibrating piece having such a structure, when an AC voltage is applied from the connection terminals 18 to the drive electrodes, the adjacent first electrodes 41a and 41b and the second electrodes 41a and 41b
As shown in FIG. 9D, electric fields E1 and E2 parallel to the respective main surfaces are generated between the electrodes 42a and 42b. 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 15b that performs a bending motion in a plane including its main surface receives air resistance in the grooves 40a and 40b. In a composite piezoelectric vibrator on which a plurality of piezoelectric vibrating reeds are mounted, the bending motion of the crystal vibrating reed 15 is more likely to be restricted as the internal volume of the package 13 is reduced as the size of the composite piezoelectric vibrator is reduced, and the CI value can be suppressed as low as expected. There is a risk of disappearing. In this embodiment, the package 13
With the above structure, the gas generated from the low melting point glass, the conductive adhesive, or the like can be suppressed, and the inside of the package can be sealed at a high degree of vacuum. Therefore, the composite piezoelectric vibrator of the present embodiment can achieve both miniaturization and a sufficient decrease in the CI value at the same time.

In FIG. 10, the tuning-fork type quartz vibrating piece 15 mounted on the lid 12 has a base end 15 similar to the embodiment of FIG.
a is an extraction electrode 4 from a drive electrode provided on the vibrating arm 15b.
3a and 43b, the corresponding connection terminals 18 and 18 on the inner surface of the lid 12 are fixed to the cantilever with a conductive adhesive 19, and the base end 15a has a portion fixed to the lid 12 and a vibrating arm 15b. U-shaped notch 44 formed between
A constricted portion 44 composed of a and 44b is provided.
As a result, the vibration of each vibrating arm 15b is
a, 44b so as not to reach the fixed portion of the base end 15a, so that the bending movement can be performed more freely, and therefore the CI
The value can be suppressed lower. In addition, the constricted portion 44 is formed by notches having various shapes other than the U-shape,
It can be formed by various recesses provided on the side of 5a.

Also in this embodiment, when air or other gas is present in the package 13 or when the degree of vacuum is low,
Since the notches 44a and 44b receive extra air resistance,
Similarly to the embodiment of FIG. 9, in particular, in a composite piezoelectric vibrator on which a plurality of piezoelectric vibrating reeds are mounted, the bending motion of the crystal vibrating reed 15 is more likely to be restricted as the internal volume of the package 13 becomes smaller as the size is reduced. , The CI value may not be suppressed as low as expected. In the tuning-fork type quartz resonator of this embodiment, since the package 13 has the above-described structure, gas generated from low-melting glass, a conductive adhesive, or the like can be suppressed, and the inside of the package can be sealed at a high degree of vacuum. Therefore, more 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.

The piezoelectric vibrating reed mounted on the composite piezoelectric vibrator of the present invention is limited to the combination of the AT cut quartz vibrating reed 14 of the base 11 and the tuning fork type quartz vibrating reed 15 of the lid 12 in the above embodiment. is not. For example, base 1
A tuning fork type crystal vibrating piece having a different oscillation frequency can be mounted on each of the first and lid 12. 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 such that the metal weights provided at the tip portions of the respective vibrating arms can be individually irradiated with the laser beam from outside the lid. Therefore, unlike the above embodiments, it is 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. It is.

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. Also in this case, similarly, the frequency can be finely adjusted by irradiating a laser beam from outside the lid. Further, an AT-cut quartz-crystal vibrating piece can be mounted on each of the base 11 and the lid 12.

The preferred embodiments of the present invention have been described in detail above. However, 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, also in the embodiment of FIG. 1, a concave portion may be provided on the inner surface of FIG. 8 and a lid containing a quartz vibrating piece therein may be used in combination. The tuning-fork type quartz vibrating reeds of FIGS. 9 and 10 can be applied in combination, or they can be applied individually or in combination to the embodiments of FIGS. Further, the present invention can be similarly applied to a piezoelectric device such as a piezoelectric oscillator in which an IC chip for driving both piezoelectric vibrating pieces is mounted in the same package.

[0050]

According to the piezoelectric device of the present invention, the first and second piezoelectric vibrating pieces are hermetically sealed in the package as described above. With the configuration equipped with the piezoelectric vibrating reed, a plurality of piezoelectric vibrating reeds of different oscillation frequencies, different types or the same type are housed in a single package to reduce its size and thickness, and at the same time, after sealing the package The frequency of the piezoelectric vibrating reed can be finely adjusted, and a composite piezoelectric vibrator having high quality and excellent stability, and a piezoelectric device such as a composite oscillator having an IC element mounted thereon can be realized.

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. Gas generated from the conductive adhesive or the like can be suppressed, and sealing can be performed at a higher degree of vacuum.
Also, the tuning fork type quartz vibrating piece mounted on this package is
It is possible to adjust the frequency more accurately after vacuum sealing, and by combining one drive electrode on the side surface of the groove provided on the main surface of the vibrating arm or a constricted part at the base end In addition, miniaturization of the piezoelectric device and suppression of the CI value can be realized at the same time.

[Brief description of the drawings]

1A is a plan view showing 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 longitudinal sectional view showing a modification of the first embodiment.

FIG. 3 is a longitudinal sectional view showing a modification of FIG. 2;

FIG. 4A is a plan view showing another modification of the first embodiment;
FIG. B is a longitudinal sectional view thereof.

5A is a plan view showing a modification of FIG. 4, and FIG. 5B is a longitudinal sectional view thereof.

FIG. 6 is a longitudinal sectional view showing still another modification of the first embodiment.

FIG. 7 is a longitudinal sectional view showing a second embodiment of the present invention.

FIG. 8 is a longitudinal sectional view showing a third embodiment of the present invention.

FIG. 9A is a longitudinal sectional view showing a modification of the first embodiment, and FIG.
The figure is a plan view thereof, the figure C is a partially enlarged view of the figure B showing the vibrating arm, and the figure D is an enlarged sectional view of the vibrating arm along the line DD in the figure C.

FIG. 10A is a longitudinal sectional view showing another modified example of the first embodiment, FIG. 10B is a plan view thereof, and FIG. 10C is a partially enlarged view of a base end portion.

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

[Explanation of symbols]

 1, 13 Package 2, 11 Base 3, 12 Lid 4 Piezoelectric vibrating reed 11a, 12a Depressed portion 14 AT-cut quartz vibrating reed 15 Tuning fork type quartz vibrating reed 14a, 15a Base end 14b, 15b Tip end 15c Gap 16, 18 Connection Terminal 17, 19 Conductive adhesive 20, 21 Internal terminal 22, 23 External electrode 24 Via hole 25 Wiring pattern 26 Conductive adhesive 27 Sealing hole 27 'Step 28 Seal material 29 Metal ball 30, 30' Laser beam 31, 32, 34 Elastic buffer portion 33 Projection 35, 36 Elastic buffer material 37 Partition wall 38 IC chip 39a, 39b Main surface 40a, 40b Groove 41a, 41b First electrode 42a, 42b Second electrode 43a, 43b Extraction electrode 44 Narrow portion 44a , 44b Notch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H03H 9/19 H03H 9/19 J

Claims (15)

[Claims] 1. A package having a base made of an insulating material, a lid made of a glass material joined to an upper surface of the base, a first piezoelectric vibrating reed mounted on the lid, and mounted on the base. And a second piezoelectric vibrating reed, wherein the first and second piezoelectric vibrating reeds are hermetically sealed in the package. 2. The first and second piezoelectric vibrating reeds are cantilevered at their base ends by the lid and the base, respectively, and the base end portions of the first and second piezoelectric vibrating reeds are provided. The piezoelectric device according to claim 1, wherein the and the tip are arranged on opposite sides. 3. The piezoelectric device according to claim 1, further comprising an IC element mounted on the base. 4. 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. 5. The terminal according to claim 4, wherein the terminal on the base side and the terminal on the lid side are electrically connected with a conductive adhesive, and at least the outside thereof is covered with a buffer.
6. The piezoelectric device according to claim 1. 6. The piezoelectric device according to claim 1, wherein the base has a rectangular box shape, and the lid has a rectangular thin plate shape. 7. The piezoelectric device according to claim 1, wherein the lid has a recess on its inner surface, and the first piezoelectric vibrating reed is accommodated in the recess. device. 8. The device according to claim 1, wherein the base has a rectangular box shape, and the lid has a recess on an inner surface thereof, and the first piezoelectric vibrating reed is housed in the recess. 1
6. The piezoelectric device according to any one of items 1 to 5, 9. The package 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 with a sealing material from the outside. The piezoelectric device according to claim 1. 10. The piezoelectric device according to claim 1, wherein the first piezoelectric vibrating reed is a tuning fork type piezoelectric vibrating reed. 11. The device according to claim 10, wherein the second piezoelectric vibrating reed is disposed at a position shifted from below a frequency adjustment region provided at a tip of the tuning fork type piezoelectric vibrating reed. Piezoelectric device. 12. The piezoelectric device according to claim 1, wherein the second piezoelectric vibrating reed is an AT-cut quartz vibrating reed. 13. The piezoelectric device according to claim 1, wherein said second piezoelectric vibrating reed is a tuning fork type piezoelectric vibrating reed. 14. At least one of the first and second piezoelectric vibrating reeds is a tuning-fork type piezoelectric vibrating reed, and the tuning fork-type piezoelectric vibrating reed comprises a first electrode formed on each main surface of a vibrating arm and the first electrode. A driving electrode comprising a second electrode formed on each side surface of the vibrating arm, wherein the first electrode is provided on at least one main surface of each vibrating arm on a side surface of a groove provided along a longitudinal direction thereof. 10. An electrode film formed by film formation.
6. The piezoelectric device according to claim 1. 15. At least one of the first and second piezoelectric vibrating reeds is a tuning-fork type piezoelectric vibrating reed, and the tuning fork-type piezoelectric vibrating reed is fixed to the base end or the base or the lid. The piezoelectric device according to claim 9, further comprising a constricted portion provided between the vibration device and the vibrating arm.