JPH03243011A - Piezo-electric resonator - Google Patents

Abstract

PURPOSE:To attain attenuation up to degree to be practically neglected by the means of spurious dumping by filling the recessed part of a case storing a piezo-electric base with an elastic material so that the periphery of the base is covered with the elastic material. CONSTITUTION:The recessed part 4a of the case 4 is filled with the elastic material 10 so that the periphery of the piezo electric base 1 is covered with the material 10. Melted elastic resin is allowed to flow from the aperture part of the case 4 into the recessed part 4a until the recessed part 4a is completely filled with the resin. Since the base 1 is vertically stored in the case 4, the front and back faces of the base 1 can be efficiently covered with the pouring elastic resin. Since the area of the lower end face of the base 1 is reduced, the sneaking quantity of the resin around the base 1 can be reduced and the formation of an air reservoir can be suppressed. Although the vibration of a main frequency band generated on the base 1 by the dumping of the elastic material 10 is slightly dumped, spurious dumping more than the practical vibration dumping is executed and a superior resonator can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a piezoelectric resonator used in filter circuits, trap circuits, and the like.

2. Description of the Related Art Conventionally, as this type of piezoelectric resonator, those shown in FIGS. 13 to 15 are known. This resonator is composed of a piezoelectric substrate 31, an insulating case 35 housing the piezoelectric substrate 31, and a sealing lid 36.

The piezoelectric substrate 31 has vibrating electrodes 32a on its front and back surfaces.

32b is completely formed. This piezoelectric substrate 31 is housed horizontally in an insulating case 35. vibrating electrode 32a,
32b is connected to lead electrodes 33a and 33b formed on the insulating case 35 via solders 34 and 34.

The sealing lid 36 is fixed to the open end of the insulating case 35 with an adhesive. Furthermore, external electrodes 38a and 38b are provided at both ends of the resonator, respectively, leading electrodes 33a and 33.
It is formed in a state where it is electrically connected to b.

By the way, the resonant frequency characteristics of this resonator include parasitic vibration,
It is known that so-called spurious signals occur. For this reason, this resonator can be used for oscillation circuits, etc., but cannot be used for filter circuits, trap circuits, etc.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a piezoelectric resonator that does not generate spurious in its resonance frequency characteristics and is easy to manufacture.

Means and Function for Solving the Problems In order to solve the above problems, a piezoelectric resonator according to the present invention includes a piezoelectric substrate provided with a vibrating electrode, and a case provided with a recess, and the recess of the case The piezoelectric substrate is housed in the case, and the concave portion of the case is filled with an elastic material so as to cover the periphery of the piezoelectric substrate.

With the above configuration, the spurious generated in the piezoelectric substrate is attenuated to a practically negligible extent by the damping effect of the elastic material surrounding the piezoelectric substrate.

As the elastic material, for example, silicone comb or the like is used. Molten silicone rubber or the like is poured into the recess of the case. In this case, the piezoelectric resonator according to the present invention is poured into the recess of the case so that the opening surface and the thickness direction of the piezoelectric substrate are parallel to each other. Preferably, the piezoelectric substrate is housed in a recess of the case. That is, since the piezoelectric substrate is stored perpendicularly to the case, the amount of molten elastic material that must go around the piezoelectric substrate when filling the recess of the case can be reduced. Therefore, air pockets are less likely to be formed, and the periphery of the piezoelectric substrate is completely covered with the elastic material.

Embodiments Hereinafter, embodiments of a piezoelectric resonator according to the present invention will be described with reference to the accompanying drawings.

[First Example, Figures 1 to 4] Figure 1 is a vertical sectional view of the resonator as seen from the front, Figure 2 is a vertical sectional view of the resonator as seen from the right side, and Figure 3 is a plan view. . The resonator includes a piezoelectric substrate 1, a case 4 housing the piezoelectric substrate 1, and an elastic material 1 covering the piezoelectric substrate 1.
It is configured from 0.

The piezoelectric substrate 1 has vibrating electrodes 2a and 2b formed on its front and back surfaces. The vibrating electrodes 2a and 2b are Ag and Ag-P.
It is formed by applying a paste such as d. The vibration mode of this piezoelectric substrate 1 is thickness shear vibration.

The insulating case 4 has a recess 4a, and cuts 5, 5 are provided on the left and right side walls of the recess 4a, and the piezoelectric substrate 1 is stored vertically in a horizontally long state using the cuts 5, 5 as a guide. It's broken. Steps 6, 6 are provided on both left and right sides of the bottom wall surface of the recess 4a to support both ends of the piezoelectric substrate 1 to prevent the vibrating portion from contacting the bottom wall surface.

Extracting electrodes 7a are formed on both sides of the case 4 and in the notches 5, 5 by a method such as sintering or vapor deposition.

7b is formed. These extraction electrodes 7a and 7b serve as one mounting pole when the resonator is mounted on a printed wiring board or the like. Vibration 1 pole 2a, 2b is solder 9°9
It is connected to extraction electrodes 7a and 7b via.

The elastic material IO is filled in the recess 4a of the case 4 and covers the circumference of the piezoelectric substrate 1. For the elastic material 10, an elastic resin such as silicone rubber is used, for example.

The molten elastic resin flows from the opening of the case 4 to the recess 4a.
is poured until it is completely filled with resin.

Since the piezoelectric substrate 1 is housed vertically in the case 4, the poured elastic resin can efficiently cover the front and back surfaces of the piezoelectric substrate 1. Moreover, the piezoelectric substrate 1
Since the area of the lower end surface is small, the amount of elastic resin that must go around the piezoelectric substrate 1 is small, making it difficult to form air pockets. The poured elastic resin becomes the elastic material 10 through a drying process.

Since the piezoelectric resonator thus obtained covers the piezoelectric substrate 1 with the elastic material 10, it does not require a sealing lid when used under conditions with little mechanical or thermal stress from the outside world. . In the piezoelectric resonator, vibrations in the main frequency band occurring in the piezoelectric substrate 1 are slightly damped due to the damping effect of the elastic material 10 covering the periphery of the piezoelectric substrate 1, but spurious waves are damped more than that. and is attenuated to a point where it can be ignored in practical terms.
This results in a piezoelectric resonator with excellent resonance frequency characteristics.

FIG. 4 is a graph showing the results of measuring the resonance frequency characteristics of a filter when this embodiment is applied to the filter.

The vertical axis shows the amount of attenuation, and the horizontal axis shows the frequency. Solid line 1 in the diagram
5 shows the resonant frequency characteristic of the filter according to this example. This filter had a main frequency band of 4.5 degrees, and silicone rubber was used as the elastic material 10. For comparison, the resonant frequency characteristic of a conventional piezoelectric resonator is shown by a dotted line 16.

FIG. 4 shows that although the main vibration around 4.5 MHz is slightly damped, spurious damping is occurring more than that.

[Second Example, Figures 5 to 7] Figure 5 is a vertical sectional view of the piezoelectric resonator as seen from the front, Figure 6 is a vertical sectional view of the piezoelectric resonator as seen from the right side, and Figure 7 is a plan view. be.

The resonator is composed of a piezoelectric substrate 21, a case 24 housing the piezoelectric substrate 21, and an elastic material 30 covering the piezoelectric substrate 21.

The piezoelectric substrate 21, which has vibrating T-poles 22a and 22b formed on its front and back surfaces, is housed horizontally in a recess 24a of the case 24 in a horizontally elongated state. Drawer I for both A rules in case 24
Poles 25a and 25b are formed. Vibration T pole 22a
, 22b is connected to the lead-out T pole 25a via solder 26.26.
, 25b is filled in the recess 24a of the case 24, and covers the piezoelectric substrate 21.

Molten elastic resin, which is the material of the elastic material 30, is poured from the opening of the case 24. In this case, since the pressure T-board 21 is housed in a horizontal state with respect to the case 24, the area of the lower surface of the pressure T-board 21 is large, and there is a possibility that air pockets may occur in that area.

However, if special means such as vacuuming are used for filling, no particular problem will occur.

The piezoelectric resonator thus obtained has excellent resonance frequency characteristics due to the damping effect of the elastic material 30.

[Other Examples] Note that the piezoelectric resonator according to the present invention is not limited to the above embodiments, and can be variously modified within the scope of the gist.

For example, in the first embodiment, depending on the processing method, the elastic material 10A has a different filling shape as shown in FIGS. 8 and 9;
IOB is obtained. Also, Figure 10, Figure 11, Figure 1
As shown in Figure 2, the sealing lids 11A, 11B, II are made of a material with excellent heat resistance, solvent resistance, and strong mechanical strength.
C may be provided.

At this time, each of the sealing lids 11A, IIB, and IIC is combined with elastic members 10C, IOD, and IOE having different filling shapes.

In particular, in the case of the piezoelectric resonator shown in FIG. 12, a modified case 4A is used.

Further, the sealing lids 11A, IIB, and IIC may have a multilayer structure in which different materials are laminated.

Effects of the Invention As described above, according to the present invention, the concave portion of the case in which the piezoelectric substrate is fully housed is filled with an elastic material so that the periphery of the piezoelectric substrate is covered with the elastic material, thereby reducing damping of the elastic material. Although this action slightly damps vibrations in the main frequency band occurring in the piezoelectric substrate, it also damps spurious components to a level that can be ignored in practical terms, making it possible to use a piezoelectric resonator with excellent resonance frequency characteristics. can get. Therefore, this piezoelectric resonator can be used for filter circuits, trap circuits, etc. Moreover, when the pressure-T resonator is used in a situation where there is little mechanical or thermal stress from the outside world, a sealing lid is not necessary, and as a result, costs can be reduced.

In addition, if the piezoelectric substrate is stored perpendicular to the case so that the opening surface of the recess in the case is parallel to the thickness direction of the piezoelectric substrate, it will be easier to fill the recess in the case with the elastic material. Since air pockets are less likely to be formed and the piezoelectric substrate is completely covered with the elastic material, workability is improved and production efficiency is improved.

[Brief explanation of drawings]

1 to 3 show a piezoelectric resonator according to a first embodiment of the present invention, FIG. 1 is a vertical sectional view of the piezoelectric resonator as seen from the front, and FIG. 2 is a vertical sectional view of the piezoelectric resonator as seen from the right side. 3 is a plan view, and FIG. 4 is a graph showing the results of measuring the resonance frequency characteristics of this piezoelectric resonator. 5 to 7 show the second embodiment, and FIG. 5, FIG. 6, and FIG. 7 are a vertical sectional view of the piezoelectric resonator as seen from the front, a vertical sectional view as seen from the right side, and a plan view, respectively. It is a diagram. Figures 8 to 12 are the first
Modifications of the embodiment are shown, and FIGS. 8, 9, 10, 11, and 12 are vertical cross-sectional views as viewed from the right side of the piezoelectric resonator. Figures 13 to 15 show conventional piezoelectric resonators, and Figures 13 to 15 show conventional piezoelectric resonators.
The figures are a vertical cross-sectional view as seen from the front, a vertical cross-sectional view as seen from the right side, and a plan view, respectively, of the piezoelectric resonator. 1... Piezoelectric substrate, 2a, 2b... Vibration T pole, 4
, 4A...Case, 4a--Concavity, 10. IOA,
IOB, IOC, IOD, IOE...elastic material,
21... Piezoelectric substrate, 22a, 22b... Vibration maple, 24... Case, 24a... Concave portion, 30...
elastic material.

Claims (2)

[Claims] 1. A piezoelectric substrate provided with a vibrating electrode and a case provided with a recess are provided, the piezoelectric substrate is housed in the recess of the case, and an elastic material is provided in the recess of the case so as to cover the circumference of the piezoelectric substrate. A piezoelectric resonator characterized by being filled. 2. 2. The piezoelectric resonator according to claim 1, wherein the piezoelectric substrate is housed in the recess of the case so that the opening surface of the case is parallel to the thickness direction of the piezoelectric substrate.