JP3378163B2 - Piezo components - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric component,
In particular, for example, the present invention relates to a piezoelectric component such as an oscillator, a discriminator, and a filter using a piezoelectric resonator that excites length vibration.

[0002]

2. Description of the Related Art FIG. 13 is a perspective view showing an example of a conventional piezoelectric component. The piezoelectric component 1 includes a support substrate 2. The pattern electrodes 3a and 3b are formed on the support substrate 2. The piezoelectric resonator 4 is supported on the support substrate 2. The piezoelectric resonator 4 includes a vibrating body 5 formed of, for example, a piezoelectric body,
The external electrodes 6a and 6b formed on both surfaces of the vibrating body 5 are included. By applying an input signal to these external electrodes 6a and 6b, length mode vibration is excited in the vibrating body 5. On one of the pattern electrodes 3a, the support member 7 is formed of, for example, a conductive material. Then, the support member 7 supports the central portion of the piezoelectric resonator 4. At the same time, the support member 7 electrically connects the one external electrode 6 a of the piezoelectric resonator 4 and the pattern electrode 3 a. The other external electrode 6b of the piezoelectric resonator 4 is connected to the pattern electrode 3b by the lead wire 8.

In such a piezoelectric component 1, in order to obtain desired characteristics, the electrical characteristics such as the resonance frequency, polarization degree, inter-terminal capacitance, etc. of the piezoelectric resonator 4 are changed depending on the dimensional design and processing conditions of the piezoelectric resonator 4. Is designed.

[0004]

However, the mechanical quality factor Qm of the piezoelectric resonator shows a unique value depending on the piezoelectric material used. Therefore, in order to set Qm to a desired value, it was necessary to develop a piezoelectric material having an optimum value or select a piezoelectric material close to the desired value. It takes a long period of time to develop a piezoelectric material, and when using a piezoelectric material having a value close to a desired value, it is necessary to endure it in a region outside the target characteristics.

Therefore, a main object of the present invention is to provide a piezoelectric component having a desired Qm by using an existing piezoelectric material.

[0006]

According to the present invention, a piezoelectric resonator for exciting a length vibration mode, a supporting substrate for supporting the piezoelectric resonator, and a central portion in the longitudinal direction of the piezoelectric resonator are used as supporting substrates. The support substrate is provided with a conductive support member and an insulating rubber-like elastic material filled between the piezoelectric resonator and the support substrate at a position where a vibration load is applied to the piezoelectric resonator. A pattern electrode is formed, and the piezoelectric resonator is a piezoelectric component that is connected to the pattern electrode via a support member. Further, the present invention provides a piezoelectric resonator that excites a length vibration mode, a support substrate for supporting the piezoelectric resonator, and a conductive support member that supports the central portion of the piezoelectric resonator in the longitudinal direction on the support substrate. Of the piezoelectric resonator supported by the supporting substrate on the surface opposite to the supporting substrate side of the piezoelectric resonator.
And an insulating rubber-like elastic which is applied in a position to provide a dynamic load member, the supporting substrate is formed a predetermined pattern electrodes, the piezoelectric resonator is connected via a support member on the pattern electrode, a piezoelectric It is a part. Furthermore, the present invention provides a piezoelectric resonator that excites a length vibration mode, a support substrate that supports the piezoelectric resonator, and a conductive substrate that supports the central portion of the piezoelectric resonator in the longitudinal direction on the support substrate. Support member and piezoelectric resonator
To the position for vibrating load, and an insulating rubber-like elastic material is filled between the the support substrate piezoelectric resonator, the piezoelectric opposite side to the supporting substrate side of the supported piezoelectric resonator by the support substrate An insulating rubber-like elastic material applied to a position where a vibration load is applied to the resonator , a predetermined pattern electrode is formed on the supporting substrate, and the piezoelectric resonator is connected to the pattern electrode via a supporting member. It is a piezoelectric component. In these piezoelectric components, the piezoelectric resonator has a base body in which a plurality of piezoelectric layers and electrodes are alternately laminated in the longitudinal direction, and the piezoelectric body layers are polarized in the longitudinal direction of the base body and have an alternating current in the longitudinal direction of the base body. It is possible to apply an electric field to excite the basic vibration of the length vibration mode utilizing the piezoelectric longitudinal effect on the substrate. Moreover, in such a piezoelectric component, a plurality of piezoelectric resonators can be connected on a supporting substrate to form a ladder filter.

By providing a rubber-like elastic material between the piezoelectric resonator and the support substrate, the upper surface of the piezoelectric resonator, or both of them, the vibration load of the piezoelectric resonator is increased. At this time, if the rubber-like elastic material filled between the piezoelectric resonator and the support substrate is made of a conductive material, electrical connection between the electrodes on the support substrate and the piezoelectric resonator can be secured.

Further, a plurality of piezoelectric resonators are connected so as to form a ladder type filter, and a rubber-like elastic material is provided between the piezoelectric resonators and the support substrate, the upper surface of the piezoelectric resonators, or both of them. By doing so, the vibration load of the piezoelectric resonator forming the ladder filter can be adjusted.

[0009]

According to the present invention, it is possible to substantially reduce Qm by increasing the vibration load of the piezoelectric resonator by the rubber-like elastic material. Therefore, a piezoelectric component having a desired Qm can be obtained by adjusting the amount of the rubber-like elastic material. Furthermore, in a ladder filter using a plurality of piezoelectric resonators, such a Q
By adjusting m, a ladder filter having good characteristics can be obtained.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments of the invention with reference to the drawings.

[0011]

1 is a perspective view showing an example of the present invention. The piezoelectric component 10 includes a support substrate 12 formed of an insulating material such as alumina. Two recesses 14 are formed at each of opposite ends of the support substrate 12.
Two pattern electrodes 1 are provided on one surface of the support substrate 12.
6, 18 are formed. One of the pattern electrodes 16 is formed between the recesses 14 facing each other, and is formed so as to extend in an L shape from one end side thereof toward the central portion of the support substrate 12. Further, the other pattern electrode 18 is formed between the other opposed concave portions 14 and is formed so as to extend in an L shape from the other end side toward the central portion of the support substrate 12.
Then, in the vicinity of the central portion of the support substrate 12, the two pattern electrodes 16 and 18 are formed so as to face each other with a space. These pattern electrodes 16 and 18 are formed so as to wrap around from the end portion of the support substrate 12 toward the other surface.

A piezoelectric resonator 20 is attached to the end portions of the pattern electrode 16 and the pattern electrode 18 in the central portion of the support substrate 12. The piezoelectric resonator 20 includes, for example, a rectangular parallelepiped base 22 as shown in FIG. Base 22
Are formed of, for example, a piezoelectric ceramic material. Base 2
Inside 2, a plurality of internal electrodes 24 are formed, as shown in FIG. The internal electrode 24 is formed so that its surface is orthogonal to the longitudinal direction of the base 22. The substrate 22 is provided on both sides of one internal electrode 24 as shown by the arrow in FIG.
It is polarized in the longitudinal direction of the base 22 so as to be opposite to each other. However, both ends of the base 22 are not polarized.

A groove 25 extending in the longitudinal direction of the base 22 is formed on one side surface of the base 22. The groove 25 is formed in the central portion of the base 22 in the width direction, and divides one side surface of the base 22 into two. Further, as shown in FIG. 4, a first insulating film 26 and a second insulating film 28 are formed on the side surfaces divided by the groove 25. On one side divided by the groove 25 on the side surface of the substrate 22, every other exposed portion of the internal electrode 24 is covered with the first insulating film 26. On the other side divided by the groove 25 on the side surface of the base 22, the internal electrode 2 not covered with the first insulating film 26 on one side of the groove 25.
Every other layer 4 is covered with the second insulating film 28.

Further, external electrodes 30 and 32 are formed on the portions of the base 22 where the first and second insulating films 26 and 28 are formed, that is, on both sides of the groove 25. Therefore,
The internal electrode 24 not covered with the first insulating film 26 is connected to the external electrode 30, and the internal electrode 24 not covered with the second insulating film 28 is connected to the external electrode 32.
That is, adjacent ones of the internal electrodes 24 are connected to the external electrodes 30 and 32, respectively.

In this piezoelectric resonator 20, the external electrodes 30,
32 is used as an input / output electrode. At this time, the base 2
An electric field is applied between the internal electrodes 24 adjacent to each other in the portions other than both end portions of 2 and thus becomes piezoelectrically active. However, at both ends of the base 22, the base 22 is not polarized, and since no electrodes are formed on both end surfaces of the base 22, an electric field is not applied and the base 22 becomes piezoelectrically inactive. Therefore, the active portion 3 for the input signal is provided at the center of the base 22.
6 is formed. In addition, inactive portions 38 for input signals are formed at both ends of the base 22. In addition, the inactive portion 38
Indicates a portion where the driving force is not generated by the input signal. Therefore, even if an electric field is applied between the internal electrodes, it is sufficient that the internal electrodes are not polarized. Also,
The structure may be such that no electric field is applied to the polarized piezoelectric layer. Such an inactive portion 38 is not essential,
The entire base 22 may be the active part.

Such a piezoelectric resonator 20 is used as the supporting substrate 1.
2 is attached on the pattern electrodes 16 and 18. At this time, the piezoelectric resonator 20 is attached to the pattern electrodes 16 and 18 via the two support members 40 formed of a conductive material. The longitudinal center portions of the external electrodes 30 and 32 of the piezoelectric resonator 20 are connected to these support members 40, respectively. A rubber-like elastic material 42 such as silicone rubber or urethane is filled between the piezoelectric resonator 20 and the support substrate 12. Further, the rubber-like elastic material 44 is also applied to the upper surface of the piezoelectric resonator 20. As such rubber-like elastic materials 42 and 44, for example, insulating rubber-like elastic materials are used.

A metal cap 46 is placed on the support substrate 12. At this time, an insulating resin is applied on the support substrate 12 and the pattern electrodes 16 and 18 so that the metal cap 46 and the pattern electrodes 16 and 18 are not electrically connected. Then, by covering the metal cap 46, the piezoelectric component 10 is manufactured. In this piezoelectric component 10, the pattern electrodes 16 and 18 formed so as to wrap around from the end portion of the support substrate 12 to the back surface are used as input / output terminals for connecting to an external circuit.

In this piezoelectric component 10, the pattern electrode 1
By inputting a signal from 6, 18 through the support member 40, mutually opposite voltages are applied to the piezoelectric layers of the active portion 36 that are polarized in opposite directions, so that the piezoelectric layers are formed as a whole. Try to expand and contract in the same direction. Therefore, the piezoelectric resonator 20 as a whole excites the fundamental mode of length vibration with the central portion of the base 22 as a node point.

In this piezoelectric component 10, the polarization direction of the active portion 36 of the piezoelectric resonator 20, the electric field direction due to a signal, and the vibration direction of the active portion 36 are the same. That is, the piezoelectric resonator 20 is a resonator that utilizes the piezoelectric vertical effect. The piezoelectric resonator 20 utilizing the piezoelectric longitudinal effect has a larger electromechanical coupling coefficient than a piezoelectric resonator utilizing the piezoelectric lateral effect in which the polarization direction and the electric field direction are different from the vibration direction. Therefore, the difference ΔF between the resonance frequency and the anti-resonance frequency is large. Therefore, by using this piezoelectric resonator 20, it is possible to obtain a characteristic having a large bandwidth.

Further, in this piezoelectric resonator 20, the active portion 3
ΔF can be adjusted by adjusting the ratio of 6 to the inactive portion 38, the formation position of the inactive portion 38, and the like. Furthermore, by adjusting the number of layers of the active portion 36,
The capacitance of the piezoelectric resonator 20 can be adjusted. Therefore, it is easy to obtain impedance matching between the piezoelectric component 10 and the external circuit.

The piezoelectric component 10 such as a discriminator and an oscillator using one such piezoelectric resonator 20 is
In both applications, phase changes near the resonance frequency (Fr) and the anti-resonance frequency (Fa) are used.
However, if the mechanical quality factor Qm of the piezoelectric resonator 20 is unnecessarily large, ripples due to unnecessary vibration occur in the usage area, and the characteristics are seriously affected.
Suppression of Qm becomes an important issue. Since the Qm of the piezoelectric resonator 20 itself is determined by the piezoelectric material of the base 22, the Qm cannot be adjusted depending on the size of the element, the number of piezoelectric layers, and the like.

Therefore, in this piezoelectric component 10, Qm is increased by the rubber-like elastic material 42 filled between the piezoelectric resonator 20 and the support substrate 12 and the rubber-like elastic material 44 provided on the upper surface of the piezoelectric resonator 20. I am adjusting. That is, the rubber-like elastic materials 42 and 44 increase the vibration load of the piezoelectric resonator 20. Thereby, the Qm of the piezoelectric resonator 20 can be substantially suppressed. in this case,
While measuring the characteristics of the piezoelectric component 10, the rubber-like elastic material 4
A desired Qm can be obtained by adjusting the amount of 2,44.

It is not always necessary to use both of the rubber-like elastic materials 42 and 44, and only one of them may be used. In this case, it is better to fill the rubber-like elastic material 42 between the piezoelectric resonator 20 and the support substrate 12
The effect of suppressing Qm is greater than that of providing the rubber-like elastic material 44 on the upper surface of 0. This is because the rubber-like elastic material 42 adheres to both the piezoelectric resonator 20 and the support substrate 12, and has a great effect of suppressing the vibration of the piezoelectric resonator 20. In this case, the rubber-like elastic material 42 reinforces the support of the piezoelectric resonator 20. However, when the Qm is adjusted while measuring the characteristics of the piezoelectric component 10, it is easier to make the adjustment by providing the rubber-like elastic material 44 on the upper surface of the piezoelectric resonator 20.

Further, as the amount of the rubber-like elastic members 42 and 44 increases, the vibration load of the piezoelectric resonator 20 increases and the effect of suppressing Qm increases. Further, since the piezoelectric resonator 20 vibrates in the length mode with the central portion as a node, the displacement at both ends becomes large. Therefore, the rubber-like elastic material 4
2, 44 are applied to the end side of the piezoelectric resonator 20,
The suppression effect of Qm becomes large.

Further, as the rubber-like elastic material 42 between the piezoelectric resonator 20 and the supporting substrate 12, for example, a conductive rubber-like elastic material such as conductive silicone can be used. In this case, as shown in FIG.
Insulating rubber-like elastic material 50 is filled in the groove 25 so as to prevent electrical connection between 0 and 32. As described above, when the conductive material is used as the rubber-like elastic material 42, the electrical conduction between the external electrodes 30 and 32 of the piezoelectric resonator 20 and the pattern electrodes 16 and 18 can be ensured. .

FIG. 6 is a plan view of a main part showing an example of the piezoelectric component 10 which is a ladder filter using a plurality of piezoelectric resonators, and FIG. 7 is a perspective view of the main part. In this piezoelectric component 10, four pattern electrodes 90, 9 are formed on the support substrate 12.
2,94,96 are formed. These pattern electrodes 9
Five lands arranged in a line at intervals are formed in 0 to 96. In this case, the first land from one end of the support substrate 12 is formed on the pattern electrode 90, the second land and the fifth land are formed on the pattern electrode 92, and the third land is formed on the pattern electrode 94. The fourth land is formed on the pattern electrode 96.

A support member 40 is provided on each of these lands.
Through the piezoelectric resonators 20a, 20b, 20c, 20d
External electrodes 30 and 32 are attached. In this case, in order to obtain the ladder type circuit shown in FIG.
0a to 20d are attached. Then, the support substrate 12
A metal cap (not shown) is overlaid on top.

The piezoelectric component 10 is used as a ladder filter having a ladder type circuit as shown in FIG.
At this time, for example, the two piezoelectric resonators 20a and 20c are used as series resonators and another two piezoelectric resonators 20a and 20c are used.
b and 20d are used as parallel resonators. With such a ladder filter, the capacitance of the piezoelectric resonators 20b and 20d in parallel is designed to be significantly larger than the capacitance of the piezoelectric resonators 20a and 20c in series. In the case of a ladder filter, as shown in FIG.
Piezoelectric resonator 2 in parallel with impedance characteristics of a and 20c
The attenuation characteristic of the filter is determined from the impedance characteristics of 0b and 20d.

In the case of such a ladder filter, the group delay characteristic (GDT) can be adjusted by adjusting the Qm of the piezoelectric resonators 20a to 20d by the rubber-like elastic materials 42 and 44. As an experimental example, the characteristics when the Qm of the series and parallel piezoelectric resonators 20a to 20d are suppressed are shown in FIG. In addition, the piezoelectric resonators 20a, 2 in series
The characteristics when Qm of 0c is suppressed are shown in FIG. Further, FIG. 12 shows the characteristics when Qm of the piezoelectric resonators 20b and 20d in parallel is suppressed. In these characteristics, the dotted line shows the group delay time before applying the elastic material, and the solid line shows the group delay time after applying the elastic material.

As can be seen from FIGS. 10, 11 and 12, the GDT deviation can be improved by suppressing the Qm of the piezoelectric resonators 20a to 20d. In particular, all the piezoelectric resonators 20a to 20d can be improved. A large effect can be obtained by suppressing Qm. It should be noted that even if the Qm of the piezoelectric resonator is adjusted, the change in the amplitude characteristic is minute, so the change in the amplitude characteristic is omitted here.

As described above, by using the rubber-like elastic materials 42 and 44, Qm can be substantially adjusted without changing the piezoelectric material. In each of the piezoelectric components 10 described above, a laminated piezoelectric resonator that uses the piezoelectric vertical effect is used as the piezoelectric resonator 20, but a piezoelectric that uses the piezoelectric lateral effect in which the polarization direction and the electric field direction are different from the vibration direction. A resonator may be used. Even when a piezoelectric resonator that vibrates in length utilizing the piezoelectric lateral effect is used, the rubber-like elastic members 42 and 44 are used to increase the vibration load and adjust the Qm of the piezoelectric resonator. be able to.

Further, in the piezoelectric component shown in FIG. 13 in which the external electrode is formed on the opposing surface of the substrate and the lead wire is used, rubber-like elasticity is provided between the piezoelectric resonator and the supporting substrate. Qm can be adjusted by filling the material with a material or by providing a rubber-like elastic material on the upper surface of the piezoelectric resonator.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an example of a piezoelectric component of the present invention.

FIG. 2 is a perspective view showing a piezoelectric resonator used in the piezoelectric component shown in FIG.

FIG. 3 is an illustrative view showing a structure of the piezoelectric resonator shown in FIG.

FIG. 4 is a plan view showing a state in which an insulating film is formed on a substrate used in the piezoelectric resonator shown in FIG.

FIG. 5 is an illustrative view showing a structure when a conductive rubber-like elastic material is used between a piezoelectric resonator and a support substrate.

FIG. 6 is a main part plan view showing an example of a piezoelectric component that is a ladder filter using a plurality of piezoelectric resonators.

FIG. 7 is an exploded perspective view of essential parts of the ladder filter shown in FIG.

8 is an equivalent circuit diagram of the ladder filter shown in FIG.

FIG. 9 is a graph showing a relationship between impedance characteristics and attenuation characteristics of a series resonator and a parallel resonator used in a ladder filter.

FIG. 10 is a graph showing characteristics when Qm of both the series resonator and the parallel resonator of the ladder filter is adjusted.

FIG. 11 is a graph showing characteristics when Qm of a series resonator of a ladder filter is adjusted.

FIG. 12 is a graph showing characteristics when Qm of a parallel resonator of a ladder filter is adjusted.

FIG. 13 is an exploded perspective view showing an example of a conventional piezoelectric component.

[Explanation of symbols]

10 Piezoelectric parts 12 Support substrate 16 pattern electrodes 18 pattern electrodes 20 Piezoelectric resonator 40 Support member 42 Rubber-like elastic material 44 Rubber-like elastic material 50 Rubber-like elastic material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tetsuo Takeshima               2 26-10 Tenjin, Tenjin, Nagaokakyo, Kyoto Prefecture               Murata Manufacturing Co., Ltd.                (56) References JP-A-60-53315 (JP, A)                 JP 60-30208 (JP, A)                 JP-A-56-69999 (JP, A)                 JP-A-8-8677 (JP, A)                 JP-A-8-172227 (JP, A)                 Japanese Patent Laid-Open No. 8-8683 (JP, A)                 JP-A-4-222109 (JP, A)                 JP-A-2-224515 (JP, A)                 JP-A-5-25202 (JP, A)                 Japanese Patent Publication 5-35607 (JP, B2)                 Japanese Patent Publication Sho 48-31368 (JP, B2)                 Japanese Examined Sho 63-24324 (JP, B2)                 Actual Kohei 3-23705 (JP, Y2)                 Actual Kohei 3-23701 (JP, Y2)

Claims (5)

(57) [Claims] 1. A piezoelectric resonator for exciting a length vibration mode, a support substrate for supporting the piezoelectric resonator, and a conductive support member for supporting a central portion of the piezoelectric resonator in a longitudinal direction on the support substrate. , And an insulating rubber-like elastic material filled between the piezoelectric resonator and the support substrate at a position where a vibration load is applied to the piezoelectric resonator, and a predetermined pattern electrode is formed on the support substrate. And the piezoelectric resonator is connected to the pattern electrode via the support member. 2. A piezoelectric resonator that excites a length vibration mode, a support substrate for supporting the piezoelectric resonator, and a conductive support member that supports the central portion of the piezoelectric resonator in the longitudinal direction on the support substrate. , And a surface of the piezoelectric resonator supported by the support substrate, the surface being opposite to the support substrate side.
Is applied to the position where a vibration load is applied to the piezoelectric resonator of
A piezoelectric component, comprising an insulating rubber-like elastic material, wherein a predetermined pattern electrode is formed on the support substrate, and the piezoelectric resonator is connected to the pattern electrode via the support member. 3. A piezoelectric resonator for exciting a length vibration mode, a support substrate for supporting the piezoelectric resonator, and a conductive support member for supporting a central portion of the piezoelectric resonator in a longitudinal direction on the support substrate. An insulating rubber-like elastic material filled between the piezoelectric resonator and the supporting substrate at a position where a vibration load is applied to the piezoelectric resonator, and the piezoelectric resonator supported by the supporting substrate. The piezoelectric on the side opposite to the supporting substrate side
An insulating rubber elastic material is provided at a position where a vibration load is applied to the resonator , a predetermined pattern electrode is formed on the support substrate, and the piezoelectric resonator is formed on the pattern electrode. A piezoelectric component connected through the support member. 4. The piezoelectric resonator has a base body in which a plurality of piezoelectric layers and electrodes are alternately laminated in the longitudinal direction. The piezoelectric layer is polarized in the longitudinal direction of the base, The piezoelectric component according to any one of claims 1 to 3, wherein an alternating electric field is applied in a direction to excite a fundamental vibration in a length vibration mode utilizing a piezoelectric longitudinal effect on the substrate. 5. The piezoelectric component according to claim 1, wherein a ladder filter is formed by connecting a plurality of the piezoelectric resonators on the support substrate.