JPH11136074A - Laminated piezo-electric resonator and ladder filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be small, also to enable adjustment of the electric coupling coefficient and capacity of a resonator, to guarantee the long-term reliability of the resonator, further to easily assemble it and to enable automation and miniaturization of assembly. SOLUTION: This resonator alternately laminates a piezo-electric layer 10 and internal electrode layers 11a and 11b and consists of a resonator body 12 where edge parts of the internal electrode layer 11a for input and the internal electrode layer 11b for output expose on sides that face each other, a belt-like external electrode 15a for input and external electrode 15b for output which connect the end parts of the electrodes 11a to each other and the end parts of the electrodes 11b to each other respectively. Here, the electrodes 15a and 15b are constituted of a flexible conductive member and also the layer 10 performs stretching vibration in the direction of lamination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric resonator utilizing a stretching vibration mode in a laminating direction, and a ladder filter using the laminated piezoelectric resonator. The present invention relates to a multilayer piezoelectric resonator and a ladder filter used in filters, oscillators, and various other applications incorporated in mobile communication devices such as cordless telephones, pagers, and car stereos.

[0002]

2. Description of the Related Art In recent years, with the development of integrated circuits, filters,
2. Description of the Related Art In an oscillator and other fields, various piezoelectric resonators using a piezoelectric body are used. Above all, from 100kHz to 1MH
Conventional piezoelectric resonators used up to z include a disk-shaped piezoelectric resonator using a radially expanding vibration mode, a square plate-shaped piezoelectric resonator using a diagonal expanding vibration mode, and a length. A rectangular plate-shaped piezoelectric resonator using a stretching vibration mode in a direction has been known.

A ladder-type filter using these piezoelectric resonators depends on the number of piezoelectric resonator elements used.
Various types such as four elements, six elements, and eight elements are known. FIG. 3 shows a circuit diagram of a six-element ladder filter. As shown in FIG. 3, the ladder-type filter connects one side electrode of the series resonators S1, S2, S3 to the input side, connects one side electrode of the parallel resonators P1, P2, P3 to the ground side, and further connects the series resonator. The other side electrodes of the daughters S1, S2, S3 and the other side electrodes of the parallel resonators P1, P2, P3 are connected to the output side.

In this type of ladder type filter, the pass band is adjusted by adjusting the size of the series resonator and the size of the parallel resonator so that the resonance frequency Fr of the series resonator matches the anti-resonance frequency Fa of the parallel resonator. And the attenuation poles are formed on both sides thereof, and the pass band is determined by the difference between the anti-resonance frequency and the resonance frequency of the piezoelectric resonator (ΔF = Fa−Fr).

FIG. 11 shows an example of the structure of a conventional ladder filter. This ladder-type filter is a four-element type filter in which two series resonators 42a utilizing a diagonally expanding vibration mode of a square plate are provided in a resin case body.
(S1, S2) and two parallel resonators 42b (P1,
P2). These series resonators 42
The area and thickness of each of the resonators a and the parallel resonators 42b are limited to certain dimensions in order to obtain desired filter characteristics.

An electrode plate 41 is disposed between the piezoelectric resonators 42a and 42b, and a U-shaped electrode plate 43 is disposed as an input or output side electrode. When the ladder-type filter is driven, it is necessary that the piezoelectric resonators 42a and 42b can vibrate in a desired state in a state of being housed in the filter case main body 44.
The vibration of the piezoelectric resonators 42a and 42b in the state where the piezoelectric resonators 42a and 42b are housed in the housing 4 must not be prevented. Therefore, conventionally, a so-called spring terminal having a spring property is used as the electrode plate 41.

FIG. 12 shows this electrode plate 41 (spring terminal).
5 shows a state in which a conventional spreading vibrator is held and fixed using the above-mentioned method. In the conventional resonator, the driving electrodes of the resonator are provided on two opposing main surfaces of the resonator, and the electrical connection and the holding and fixing of the resonator are performed by using the electrode plate 41 (spring terminal) from both sides of the resonator. It was done in such a way as to pinch it.

On the other hand, in recent years, for example,
As disclosed in Japanese Patent Application Laid-Open No. 1-133715, there is known a laminated piezoelectric resonator in which piezoelectric layers and internal electrode layers are alternately laminated.

This laminated piezoelectric resonator is composed of a resonator main body in which piezoelectric layers and internal electrode layers are alternately laminated, and a pair of external electrodes formed in the laminating direction. End portions of the internal electrode layers are alternately exposed on both side surfaces of the resonator body, and external electrodes are respectively connected to the exposed portions. These external electrodes are formed by forming notches on both side surfaces of the resonator main body and baking silver paste in the notches.

[0010]

However, the laminated piezoelectric resonator disclosed in Japanese Patent Application Laid-Open No. S61-133715 uses a spread vibration mode and uses a diagonal spread vibration mode of a square plate. For example, when used for a 455 filter, one side of the square is about 5 mm, and the thickness is 0.3 to 1.0 mm, so that further miniaturization was impossible.

In an electronic component such as a ladder-type filter, a piezoelectric resonator is used at a resonance frequency of vibration. Therefore, if the piezoelectric resonator is used for a long time, it is generated on an external electrode formed on the resonator. There has been a problem that the external electrode is easily disconnected due to tensile stress.

In particular, in a resonator that uses a stretching vibration in the laminating direction by alternately laminating piezoelectric layers and internal electrode layers (this resonator is not yet known), an input signal is generated by the stretching vibration in the laminating direction. There is a problem that the disconnection of the external electrode and the output external electrode occurs, and the reliability is impaired.

The present invention provides a laminated piezoelectric resonator which is smaller in size, can adjust the electromechanical coupling coefficient and the capacitance, and can obtain high reliability, and can be easily assembled, and can be assembled automatically. It is an object of the present invention to provide a ladder-type filter that can be miniaturized, has characteristics equal to or higher than conventional ones, and can guarantee high reliability.

[0014]

A laminated piezoelectric resonator according to the present invention comprises piezoelectric layers and internal electrode layers alternately laminated,
A resonator body in which the internal electrode layers are alternately formed as input internal electrode layers or output internal electrode layers, and ends of the input internal electrode layer and the output internal electrode layer are alternately exposed on side surfaces facing each other; A band-shaped input external electrode and an output external electrode are respectively formed on both side surfaces of the resonator main body, and connect the ends of the input internal electrodes and the ends of the output internal electrodes. The input external electrode and the output external electrode are formed of a flexible conductive member, and the piezoelectric layer performs stretching vibration in the laminating direction.

Further, the laminated piezoelectric resonator of the present invention is formed by alternately laminating piezoelectric layers and internal electrode layers, and the internal electrode layers are alternately formed with the input internal electrode layers or the output internal electrode layers. And a resonator main body in which ends of the input internal electrode layer and the output internal electrode layer are exposed on the same side surface, and are formed on the same side surface of the resonator main body, and end portions of the input internal electrode and An input external electrode and an output external electrode for connecting the ends of the output internal electrode to each other, and the input external electrode and the output external electrode are formed of a flexible conductive member. The piezoelectric layer performs stretching vibration in the laminating direction. Here, it is preferable that a flexible insulating member is provided on a side surface facing the side surface on which the input external electrode and the output external electrode are formed.

Further, the ladder-type filter according to the present invention is a ladder-type filter comprising a plurality of series resonators and a plurality of parallel resonators, wherein the series resonator and the parallel resonator are different from the laminated piezoelectric resonator. It becomes.

[0017]

The laminated piezoelectric resonator of the present invention uses a material having a large electromechanical coupling coefficient for elongational vibration in the polarization direction.
It can stretch vibration of the electromechanical coupling coefficient K ₃₃ in the stacking direction to obtain a sufficiently large piezoelectric resonator.

The electromechanical coupling coefficient of the PZT-based material differs greatly by the vibration mode, as compared with the electromechanical coupling coefficient K ₃₁ of conventional transverse effect, elongation vibration in the thickness direction (longitudinal effect)
Since the electromechanical coupling coefficient K ₃₃ is large, in particular, it is large the effect in case of using PZT-based materials as the piezoelectric layer. Electric PZT-based material coupling coefficient K ₃₃
Is about 50% or more and about 70%.

In the resonator having such a laminated structure, it is possible to obtain resonators having various capacitances by adjusting the number of opposing electrodes and the thickness between the electrodes. With such a configuration, the shape of the resonator can be reduced in size, and a large-capacity resonator can be obtained.

Further, by forming the input external electrode and the output external electrode with flexible conductive members, disconnection of the external electrodes due to tensile stress generated by expansion and contraction vibration of the resonator can be prevented. The present inventors have realized a miniaturization, and as a piezoelectric resonator capable of adjusting the electromechanical coupling coefficient and the capacity, alternately stack piezoelectric layers and internal electrode layers, and use stretching vibration in the stacking direction. (Japanese Patent Application No. 9-140145). In this case, the tensile stress of the external electrode is particularly increased due to stretching vibration, but the external electrode is formed of a flexible conductive member. By doing so, it is possible to minimize the tensile stress generated in the external electrodes.

When the resonator is held and connected to the ladder filter circuit, the connection is held by the external electrodes of the resonator.
At this time, since the external electrode is formed of a flexible conductive member, compressive stress is applied to the flexible conductive member even if the external electrode is firmly held, and the holding does not hinder the expansion and contraction vibration of the resonator. .

Further, even when a shock such as a drop occurs in a mobile communication device equipped with the resonator of the present invention, the shock can be absorbed by an external electrode to reduce the shock and prevent breakage. it can.

The inventors of the present invention have also applied for a laminated piezoelectric resonator in which an external electrode for input and an external electrode for output are formed on the same side surface of the resonator body (Japanese Patent Application No. Hei 9 (1994) -209).
In this case as well, the tensile stress of the external electrode due to the stretching vibration increases, but the tensile stress generated in the external electrode is minimized by forming the external electrode with a flexible conductive member. It is possible to prevent disconnection of external electrodes due to expansion and contraction vibration, and when connecting a laminated piezoelectric resonator to a ladder type circuit, simply connect it to the terminal that connects the external input electrode and external output electrode and make electrical connection Becomes possible.

Further, by providing a flexible insulating member on the side surface opposite to the surface on which the external electrodes are formed, the position of the laminated piezoelectric resonator can be fixed by suppressing this portion from above. In this case, since the resonator is in contact with the case of the filter or the like via the flexible insulating member, the vibration is not prevented by the holding. Therefore, electrical connection between the laminated piezoelectric resonator and the ladder-type circuit is facilitated, and assembly is facilitated.

Further, by forming a concave portion in the resonator main body between the input external electrode and the output external electrode, the input external electrode and the output external electrode can be reliably separated from each other. Insufficient insulation can be prevented during the assembly of the device.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 shows a laminated piezoelectric resonator of the present invention. In FIG. 1, reference numeral 10 indicates a piezoelectric layer mainly composed of Pb (Zr, Ti) O ₃ . Examples of the piezoelectric layer 10 include Pb, Zr, and Tb of Pb (Zr, Ti) O _3.
Part of i is an alkaline earth metal such as Ba, a group 5a element in the periodic table such as Nb, a rare earth element such as Y, a group 6a element in the periodic table such as Cr, and a group VIII in the periodic table such as Co. Those substituted with elements or the like are used.

The five piezoelectric layers 10 and the four A layers
The electrode layers 11 made of a conductive material such as g-Pd are alternately laminated, and the input internal electrodes 11a and the output internal electrodes 1 are alternately arranged.
1b, and the resonator main body 12 is formed. The ends of the internal electrode layers 11 are alternately exposed on the side surfaces of the resonator body 12, and the end portions of the internal electrode layers 11 are formed on both sides of the resonator body 12 in the form of a band-like input. They are connected by an external electrode 15a and an output external electrode 15b.

These external electrodes 15a and 15b are
It is desirable that the width B be 0.1 to 0.3 mm as shown in FIG. External electrodes 15a and 15b have a width of 0.1 m
If it is thinner than m, it may be broken, 0.3mm
When the external electrodes 15a, 15b
Unnecessary capacitance is generated between the electrodes and between the external electrodes 15a and 15b and the internal electrode layer 11, so that the pass band width ΔF is narrowed and the vibration of the resonator is further restricted.

The external electrodes 15a and 15b are formed of a flexible conductive member, for example, conductive silicon rubber.

The piezoelectric layer 10 is polarized in the laminating direction X, and the vibration direction is the laminating direction X of the piezoelectric layer 10. The node of the vibration is about 1/2 of the length of the resonator main body 12 in the stacking direction X of the piezoelectric layer 10.

As shown in FIG. 2, the laminated piezoelectric resonator of the present invention has a green sheet 16 of a piezoelectric ceramic containing Pb (Zr, Ti) O ₃ as a main component, and the lower four green sheets. An electrode pattern is formed on the upper surface of the green sheet 16 by screen printing or the like.
No electrode pattern is formed. After stacking such green sheets of the same thickness such that the position of the electrode pattern is at a predetermined position, by pressing and firing simultaneously, a sintered body in which a piezoelectric layer is laminated via an internal electrode layer Can be obtained.

Next, the sintered body obtained as described above is cut into a product shape. After cutting,
A flexible conductive paste is applied to the exposed portion of the electrode layer,
Dry to form a strip-shaped external electrode. Thereafter, a DC voltage is applied between the external electrodes to perform a polarization process to impart piezoelectricity.

Prior to lamination, a thin plate of piezoelectric ceramic having a uniform and flat thickness is fired, a conductive paste for an internal electrode layer is applied to the thin plate of piezoelectric ceramic, dried, and the electrode of each thin plate is dried. The piezoelectric ceramics may be bonded via electrodes by laminating the patterns in a form in which the positions of the patterns are accurately adjusted.

[0034] In the multilayer piezoelectric resonator of the present invention, the coupling coefficient of the PZT-based material, as compared with the electromechanical coupling coefficient K ₃₁ of transverse effect, the electromechanical coupling coefficient K of the elongation vibration in the thickness direction (longitudinal effect) _{Since 33} is large, it is possible to obtain a piezoelectric resonator having a sufficiently large electromechanical coupling coefficient K ₃₃ for elongational vibration in the stacking direction. Resonators with various capacitances can be obtained by adjusting the number of opposing electrode layers and the thickness between the electrode layers. Therefore, in the multilayer piezoelectric resonator of the present invention, the size of the resonator can be reduced, and a large-capacity resonator can be obtained.

That is, the length of the resonator body in the stacking direction X of the piezoelectric layers is L, the number of stacked piezoelectric layers is n, the interval between the electrode layers is t (L / n), and the area for forming the capacitor (electrode Assuming that the area where the layers overlap is a × b, the total capacitance C is represented by C = ε ₀ ε _rn ² ab / L. The length L of the resonator body is determined by the used resonance frequency fr and the antiresonance frequency fa. For example, when the resonance frequency fr is 400 kHz, L is 4 mm. Number of layers n
Is determined from the required capacitance value. Further, the above a,
The value of b is determined by the shape of the device used.

FIG. 3 is a circuit diagram of a ladder-type filter, which shows a difference Δ between the resonance frequency and the anti-resonance frequency.
F is the same as series resonators S1, S2, S3 and parallel resonator P
A ladder-type filter is disclosed in which three basic unit circuits, each having an L-type connection of P1, P2, and P3, are connected.

Then, the resonators S1, S2, S3, P1,
The laminated piezoelectric resonator of the present invention is used as P2 and P3. When a laminated piezoelectric resonator is incorporated, the node of vibration is the resonator body 1 in the laminating direction X of the piezoelectric layer 10.
Since this is near the center of 2, this portion is held. In other words, reference numeral 20 shown in FIG. 1 is a holding member, and is connected to a device circuit via the holding member 20.

Note that the width B of the external electrodes 15a and 15b is equal to 0.1.
1 to 0.3 mm is desirable, but in the example of FIG. 1, as shown in FIG.
Although the example in which it is formed at the position where the center portion of the resonator opposes has been described, as shown in FIG. 5, it may be formed at the position where the end portion of the resonator main body 12 opposes, and as shown in FIG. May be formed. In particular, as shown in FIG. 6, it is preferable to form them so as not to face each other so as not to generate unnecessary capacitance.

Although FIG. 1 illustrates a laminated piezoelectric resonator in which four internal electrode layers are formed, the present invention is not limited to the above example, and five or more internal electrode layers may be formed. Of course, it may be possible.

The material of the piezoelectric layer 10 is a piezoelectric material other than the above-mentioned Pb (Zr, Ti) O ₃ type, for example, Pb
TiO ₃ or the like may be used.
Electromechanical coupling coefficient K ₃₃ may be a material of 50% or more.

Embodiment 2 Another laminated piezoelectric resonator of the present invention will be described. As the piezoelectric layer, the same as in the first embodiment is used.
Then, as shown in FIG. 7, 27 such piezoelectric layers 31 and 26 internal electrode layers 32 made of a conductive material such as Ag-Pd are alternately laminated to form a resonator main body 33. ing. The internal electrode layers 32 are alternately formed as input internal electrode layers 32a or output internal electrode layers 32b, and these input internal electrode layers 32a and output internal electrode layers 32b are formed.
Are exposed in different regions on the side surface of the resonator main body 33 as shown in FIG.

That is, the end of the input internal electrode layer 32a is
The end of the output internal electrode layer 32b is exposed on the near side of the side face of the resonator main body 33 shown in FIG. The input internal electrode layer 32a and the output internal electrode layer 32b have shapes as shown in FIGS. 8B and 8C.

As shown in FIG. 7, the ends of the input internal electrode layers 32a are connected to each other by input external electrodes 34a formed on the front side of the side surface of the resonator main body 33, and The ends of the internal electrode layers 32b are connected to each other by external output electrodes 34b formed on the inner side of the resonator body 33. That is, the input external electrode 3
The external electrodes 4 a and the output external electrodes 34 b are juxtaposed on the same side surface of the resonator main body 33 in the direction in which the piezoelectric layers 31 are stacked.

A recess 35 is formed between the input external electrode 34a and the output external electrode 34b.
Further, the input external electrode 34a and the output external electrode 34
A flexible insulating member 37 is formed on a side surface opposite to the surface on which b is formed.

The piezoelectric layer 31 is polarized in the stacking direction X, and the polarization direction z in the adjacent piezoelectric layer 31 is opposite. The vibration direction is the stacking direction X of the piezoelectric layer 31.
It has been. The node of the vibration is about half the length of the resonator body 33 in the stacking direction X of the piezoelectric layer 31.

Next, FIG. 9 shows a method of manufacturing a laminated piezoelectric resonator in the case where seven piezoelectric layers 31 are laminated. First, P
A green sheet 36 of piezoelectric ceramics containing b (Zr, Ti) O ₃ as a main component is prepared, and the upper surfaces of the six green sheets 36 are screen-printed or the like as shown in FIGS. 8B and 8C. An electrode pattern is formed, and no electrode pattern is formed on the uppermost green sheet 36.
After stacking such green sheets of the same thickness so that the position of the electrode pattern is at a predetermined position, crimped,
By sintering at the same time, a sintered body in which the piezoelectric layer 31 is laminated via the internal electrode layer 32 as shown in FIG. 8 can be obtained.

Next, a flexible conductive member, for example, a conductive rubber sheet is attached to the exposed portion of the internal electrode layer 32 to form the input external electrode 34a and the output external electrode 34b. In addition, a flexible insulating member 37 is formed on a side surface opposite to the side surface on which the external electrodes are formed, for example, by attaching an insulating rubber sheet. Although an example in which a rubber sheet is used as the flexible conductive member and the insulating member has been described, the shape is not limited to a sheet-like material, and a paste-like material that is applied and dried and fixed may be used. Any material may be used as long as the elastic constant in the state is at least one order of magnitude smaller than the elastic constant of the piezoelectric body and does not hinder vibration and does not break.

Next, grooves for insulating these external electrodes 34 are formed in the resonator body 33 between the input external electrode 34a and the output external electrode 34b by a dicing saw or the like.

Thereafter, a DC voltage is applied between the input external electrode 34a and the output external electrode 34b to perform a polarization process to impart piezoelectricity. Thereafter, the laminate is cut into a predetermined resonator shape to obtain the multilayer piezoelectric resonator of the present invention.

Before lamination, a flat and flat piezoelectric ceramics plate having a uniform thickness is prepared, a conductive paste for an internal electrode layer is applied to the piezoelectric ceramics plate, and dried.
The piezoelectric layers may be joined via the internal electrode layers by laminating and baking the thin plates in such a manner that the positions of the electrode patterns are accurately matched.

In the laminated piezoelectric resonator of this embodiment, the PZT
The coupling coefficient of the system material is the electromechanical coupling coefficient K ₃₁ of the transverse effect.
Compared to, since the electromechanical coupling coefficient K ₃₃ of stretch vibration in the thickness direction (longitudinal effect) is larger, it is possible to electro-mechanical coupling coefficient K ₃₃ of stretch vibration in the stacking direction to obtain a sufficiently large piezoelectric resonator. Resonators with various capacitances can be obtained by adjusting the number of opposing electrode layers and the thickness between the electrode layers. Therefore, in the multilayer piezoelectric resonator of the present invention, the size of the resonator can be reduced, and a large-capacity resonator can be obtained.

The laminated piezoelectric resonator of this embodiment is also used as the resonators S1, S2, S3, P1, P2, and P3 of the ladder-type filter as shown in FIG.

When a laminated piezoelectric resonator is incorporated, the node of vibration is near the center of the resonator main body 33 in the laminating direction X of the piezoelectric layer 31, so that the ladder filter circuit is printed at this portion. It is connected and fixed to such a substrate.

That is, in the laminated piezoelectric resonator, it is desirable that a portion indicated by a dashed line in FIG. 7 is connected to the substrate. Electrical connection is made by pressing an external electrode against the printed circuit electrode surface. Further, the adhesive may be fixed with a paste made of flexible conductive rubber. FIG. 10 shows a state in which the laminated piezoelectric resonator is bonded to a substrate. In FIG.
Is a conductive rubber-like paste having elasticity.
Reference numeral 9 denotes a substrate on which a ladder-type filter circuit is printed.

Therefore, in the ladder type filter of the present invention,
Since the input external electrode 34a and the output external electrode 34b are formed on the same side surface of the resonator main body 33, when connecting the laminated piezoelectric resonator to a ladder type circuit, it is arranged on the terminal of the substrate 39, and the input external electrode 34a and the output external electrode 34b can be connected only by bonding and fixing with an elastic paste, and the electrical connection between the laminated piezoelectric resonator and the ladder-type circuit is easy, so that the ladder-type filter can be assembled. It will be easier.

Since the concave portion 35 is formed in the resonator body 33 between the input external electrode 34a and the output external electrode 34b, the input external electrode 34a and the output external electrode 34b can be reliably separated. Thus, occurrence of insulation failure in assembling the resonator can be prevented. Further, by suppressing the flexible insulating member 37 from above, the laminated piezoelectric resonator can be fixed without inhibiting vibration.

In FIG. 7, there are 27 piezoelectric layers 31 and FIG.
In the above, the laminated piezoelectric resonator in which seven piezoelectric layers 31 are formed has been described. However, the present invention is not limited to the above-described example, and it is sufficient that the piezoelectric layer 31 has three or more piezoelectric layers. Of course.

[0058]

【Example】

Example 1 First, as a starting material, commercially available PbO, TiO ₂ , Zr having a purity of 99.5% or more and an average particle size of 1.0 to 3.0 μm.
O ₂ , Nb ₂ O ₅ , Y ₂ O ₃ , Cr ₂ O ₃ , Co
_A predetermined amount of each powder of ₃ O ₄ , La ₂ O ₃ and SrCO ₃ was weighed, and the composition formula (Pb _0.96 Sr _0.03 La _0.01 ) _1.00 (N
b _0.50 Cr _0.40 Y _0.07 Co _0.03 ) _0.10 Ti _{0.45 9} Zr
Five green sheets represented by _0.441 O ₃ were produced. An electrode pattern was formed on the upper surface of the four green sheets by screen printing, and no electrode pattern was formed on one green sheet.

The green sheet having the same thickness as described above is
As shown in FIGS. 1 and 2, the electrode patterns are stacked so that the positions of the electrode patterns are located at predetermined positions, and then pressure-bonded.
Simultaneously firing at 150 ° C, the thickness of one piezoelectric layer is 0.8
mm was obtained.

Next, the sintered body obtained in this manner was cut, and the size of the product shape was changed to a ₁ = 1 m in FIG.
A resonator main body with m, b ₁ = 0.5 mm and L = 4 mm was manufactured. Thereafter, a conductive silicon rubber paste was applied to the exposed portions of the internal electrode layers and dried to form input / output external electrodes having a width of 0.2 mm.

This was immersed in insulating oil at 80 ° C., and polarized by applying a DC voltage of 3 kV / mm to both end surfaces for 30 minutes. Thereafter, in order to stabilize the polarization state, heat treatment was performed at 220 ° C. for one hour to obtain a laminated piezoelectric resonator as shown in FIG.

The bandwidth ΔF of the laminated piezoelectric resonator was determined from the values of the resonance frequency Fr and the anti-resonance frequency Fa measured by an impedance analyzer, and the capacitance was further measured.

Instead of the conductive silicon rubber paste, a paste made of Ag and glass is applied, dried, and baked at 520 ° C. to form external electrodes, and the resonance frequency Fr, anti-resonance frequency Fa, and bandwidth ΔF, the capacity was determined. As a result, also in the case of the product of the present invention and the external electrode made of Ag and glass, the capacitance was 73.5 pF and the bandwidth ΔF was 37.
kHz.

Further, an AC voltage of ± 10 V and 450 kHz was applied to the laminated piezoelectric resonator of the present invention having external electrodes made of conductive silicon rubber paste and the laminated piezoelectric resonator having external electrodes made of Ag and glass. Apply 10
As a result of performing an acceleration test for 00 hours and confirming the operation every 100 hours, the resonator of the present invention was confirmed to operate even after 1000 hours had elapsed. Stopped working. When this resonator was observed with a metallographic microscope, disconnection of the external electrode was confirmed.

Example 2 First, commercially available PbO, TiO ₂ , Zr having a purity of 99.5% or more and an average particle size of 1.0 to 3.0 μm were used as starting materials.
O ₂ , Nb ₂ O ₅ , Y ₂ O ₃ , Cr ₂ O ₃ , Co
_A predetermined amount of each powder of ₃ O ₄ , La ₂ O ₃ and SrCO ₃ was weighed, and the composition formula (Pb _0.96 Sr _0.03 La _0.01 ) _1.00 (N
b _0.50 Cr _0.40 Y _0.07 Co _0.03 ) _0.10 Ti _{0.45 9} Zr
Seven green sheets represented by _0.441 O ₃ were produced. Electrode patterns were formed on the upper surfaces of the six green sheets by screen printing, and no electrode patterns were formed on one green sheet.

The green sheets having the same thickness as described above are
As shown in FIG. 9, after the electrodes are stacked so that the positions of the electrode patterns are at predetermined positions, they are pressed and baked simultaneously at 1150 ° C. in the air to form a sintered body having a piezoelectric layer having a thickness of 0.57 mm. Obtained.

Next, a conductive silicon rubber paste is applied to the surface of the sintered body thus obtained (the surface on which the external electrodes are to be formed), dried, and the input external electrode and the output external electrode are applied. Was formed. An insulating silicon rubber paste was applied to the surface on the opposite side of the sintered body and dried. Next, a width of 0.1 m is provided between the input external electrode and the output external electrode.
A groove having a depth of m and a depth of 0.05 mm was formed using a dicing saw. This is immersed in insulating oil at 80 ° C.
Polarization treatment was performed by applying a DC voltage of kV / mm for 30 minutes. Thereafter, in order to stabilize the polarization state, heat treatment was performed at 220 ° C. for 1 hour. Finally, the product was cut using a dicing saw, and the size of the product shape was 1 mm × 0.5 mm × 4 mm.
Was manufactured.

The bandwidth ΔF of the laminated piezoelectric resonator was determined from the values of the resonance frequency Fr and the antiresonance frequency Fa measured by an impedance analyzer, and the capacitance was further measured. In place of the conductive silicone rubber paste, A
g and a paste consisting of glass, and then dried.
Regarding the device formed by baking at an external electrode at ℃, the resonance frequency Fr, the anti-resonance frequency Fa, the bandwidth ΔF, and the capacitance were obtained. As a result, in the case of the product of the present invention and the external electrode made of Ag and glass, the capacitance was 130 pF and the bandwidth ΔF was 3
It was 7 kHz. From this, it can be seen that it has excellent characteristics.

Further, as for this resonator, an acceleration test was carried out in the same manner as in the first embodiment, and as a result, the operation of the resonator of the present invention was confirmed after 1000 hours. The resonator no longer operates after 500 hours. When this resonator was observed with a metallographic microscope, disconnection of the external electrode was confirmed.

[0070]

As described in detail above, the multilayer piezoelectric resonator of the present invention is smaller in size, and the electric coupling coefficient and the capacitance of the resonator can be adjusted. When this resonator is used as a device, the electrical connection can be easily made, and the external electrodes for input and output are made of a flexible conductive member, for example, a conductive rubber. Because of the formation, disconnection of the external electrode can be prevented, and a short circuit between the input and output can be prevented by providing an insulating groove between the input and output electrodes, and a resonator for a device such as a filter or an oscillator. When used, the assembly process can be simplified and the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a laminated piezoelectric resonator of the present invention.

FIG. 2 is a perspective view illustrating a method for manufacturing a piezoelectric resonator according to the present invention.

FIG. 3 is a circuit diagram of a ladder-type filter.

FIG. 4 is a plan view of FIG. 1;

FIG. 5 is a plan view showing an example in which a strip-shaped external electrode is formed facing an end of a resonator main body.

FIG. 6 is a plan view showing an example in which external electrodes are formed so as not to face each other.

FIG. 7 is a perspective view showing another laminated piezoelectric resonator of the present invention.

FIG. 8 is a perspective view showing a resonator main body of the laminated piezoelectric resonator before forming an input external electrode and an output external electrode, and a plan view showing the shape of internal electrodes.

FIG. 9 is a perspective view for explaining the method for manufacturing the multilayer piezoelectric resonator of the present invention.

FIG. 10 is a cross-sectional view showing a state in which the multilayer piezoelectric resonator of the present invention is bonded to a substrate.

FIG. 11 is a sectional view showing a conventional ladder-type filter.

FIG. 12 is a sectional view showing a holding state of a conventional piezoelectric resonator.

[Explanation of symbols]

 10, 31 ... piezoelectric layer 11, 32 ... internal electrode layer 11a, 32a ... input internal electrode layer 11b, 32b ... output internal electrode layer 12, 33 ... resonator body 15 , 34 ... external electrodes 15a, 34a ... input external electrodes 15b, 34b ... output external electrodes 35 ... recesses 37 ... flexible insulating members

Claims (4)

[Claims] A piezoelectric layer and an internal electrode layer are alternately laminated, and said internal electrode layers are alternately used as an input internal electrode layer or an output internal electrode layer. End portions of the internal electrode layers are alternately exposed to the side surfaces facing each other, and the end portions of the input internal electrodes are formed on both side surfaces of the resonator main body, and the end portions of the input internal electrodes and the output internal electrode A belt-shaped input external electrode and an output external electrode for connecting the end portions to each other, the input external electrode and the output external electrode being formed of a flexible conductive member, A laminated piezoelectric resonator, wherein the layers perform stretching vibration in the laminating direction. 2. The method according to claim 1, wherein the piezoelectric layers and the internal electrode layers are alternately laminated, and the internal electrode layers are alternately used as input internal electrode layers or output internal electrode layers. The end of the internal electrode layer for the resonator body is exposed on the same side, the end of the input internal electrode and the end of the output internal electrode are formed on the same side of the resonator main body. An external electrode for input and an external electrode for output connected to each other, the external electrode for input and the external electrode for output are formed of a flexible conductive member, and the piezoelectric layer expands and contracts in the laminating direction. A laminated piezoelectric resonator that vibrates. 3. A laminated piezoelectric resonator according to claim 2, wherein a flexible insulating member is provided on a side surface opposite to the side surface on which the input external electrode and the output external electrode are formed. . 4. A ladder-type filter comprising a plurality of series resonators and a plurality of parallel resonators, wherein the series resonator and the parallel resonator comprise the laminated piezoelectric resonator according to claim 1 or 2. A ladder-type filter characterized by the following.