JPH03247010A - Piezoelectric resonator - Google Patents

Abstract

PURPOSE:To suppress generation of migration and solder bridge and to conform to miniaturization by forming capacitance with an input output electrode and a common electrode and an internal electrode and the common electrode respectively. CONSTITUTION:Input output electrodes A, B and a common electrode C are formed to left/right ends of an oscillator 1 and in the middle respectively, an electrode 4a and internal electrodes 6a, 7a are connected to the electrode A and a leadout electrode 4b and internal electrodes 6b, 7b are connected to the other electrode B. Moreover, the electrode C is formed in stripes in the middle, the electrodes A-C are used as mount electrodes to a printed circuit board or the like and the function as the capacitance electrode is provided. That is, static capacitances C1, C2 are formed between the electrodes A-C and between the electrodes B-C. Furthermore, the common electrode C and the internal electrodes 6a, 6b, 7a, 7b and sealing bases 5, 8 form capacitance to obtain synthesized capacitances Ca, Cb. Thus, production of migration or solder bridge is suppressed conforming to miniaturization of components.

Description

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

As a circuit using a piezoelectric resonator, for example, an oscillation circuit shown in FIG. 10 is known. This circuit consists of input and output electrodes (A
), (B), and capacitances C1, C2 are connected between the input/output electrodes (A), (B) and the common electrode (C), respectively.

To configure the circuit shown in FIG. 10, the circuit shown in FIGS.
A condenser built-in oscillator 30 shown in the figure can be considered. This oscillator 30 includes one piezoelectric substrate 31 and two sealing substrates 3.
Consists of 4.35.

As the piezoelectric substrate 31, a piezoelectric ceramic substrate or the like is used. Vibrating electrodes 32a are provided on the upper and lower surfaces of the center of the substrate 31.

32b are formed facing each other. Vibrating electrode 32a93
2b are connected to extraction electrodes 33a and 33b, respectively. This substrate 31 and a sealing substrate 34.35 stacked in the thickness direction are fixed with an adhesive 37.37,
The thickness of the adhesive layer forms a sealed vibration space (Fig. 13). Dielectric substrates are used as the sealing substrates 34 and 35.

FIG. 12 shows the appearance of the oscillator 30 fixed with adhesive 37.37. Input/output electrodes (A) and (B) are formed connected to extraction electrodes 33a and 33b, respectively. Similarly, a common electrode (C) is formed in a strip shape at the center of the oscillator 30. These electrodes (A).

(B) and (C) are used as electrodes when attached to a printed wiring board, etc., and also have a function as a capacitive electrode. That is, between electrodes (A) and (C) and between electrodes (B) and
(C) Capacitances C1 and C2 are formed between them.

Usually, the capacitance C1 that this capacitor built-in oscillator 30 has
, C2 are capacities that can be used practically.

By the way, if it is necessary to further increase the DIE capacitances C1 and C2, the distance between electrodes (A) and (C) and between electrodes (B)
- (C) or narrow the gap between the electrodes (A
), (B), and (C) need to increase the opposing area formed by them. However, when the gap is narrowed, migration is likely to occur, and there is also a risk that solder bridges may occur during soldering, resulting in a short circuit. Furthermore, if the opposing area is increased, a problem arises in that the parts become larger.

Therefore, an object of the present invention is to provide a piezoelectric resonator with a built-in capacitor that is less likely to cause migration or solder bridging even when the capacitance is increased, and that can accommodate miniaturization of components. It is in.

Means for Solving the Problems In order to solve the problems above, the piezoelectric resonator according to the present invention is provided with an internal electrode connected to the input/output electrode on the vibration space forming side surface of the dielectric sealing member. The electrode and the common electrode, and the internal electrode and the common electrode each form a capacitor part.

Effect In the above configuration, capacitance is obtained not only between the input/output electrode and the common electrode, but also between the common electrode and the internal electrode, so that the capacitance increases.

Therefore, a large capacitance can be obtained without narrowing the gap between the input/output electrode and the common electrode, eliminating concerns about migration, solder bridging, etc. Further, even if the external dimensions of the parts are reduced, a practically sufficient capacity can be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a piezoelectric resonator according to the present invention will be described together with a method for manufacturing the same. Although the piezoelectric resonator will be described using an oscillator used in an oscillation circuit as an example, the present invention is not limited to this, and may be a resonator used in a filter circuit or the like.

[First Embodiment, FIGS. 1 to 4] FIG. 1 shows an exploded perspective view of a three-terminal resonator 1 with a built-in capacitor. This oscillator 1 is composed of one piezoelectric substrate and two dielectric sealing substrates. The piezoelectric substrate 2 has vibrating electrodes 3a and 3b formed on its upper and lower surfaces. Further, the electrode 3a is connected to an extraction electrode 4a formed on the left side of the substrate 2, and the electrode 3b is connected to an extraction electrode 4b formed on the right side of the substrate 2. The piezoelectric substrate 2 contains Pb
(ZrTi)On, Bal10m ceramic substrates, etc. are used.

Dielectric substrates such as BariOs can be used as the sealing substrates 5 and 8. Two internal electrodes 6a are provided on the left and right sides of the bottom surface of the sealing substrate 5.
, 6b are formed. One end of the internal electrode 6a is exposed on the left side of the substrate 5, and one end of the internal electrode 6b is exposed on the right side of the substrate 5. Two internal electrodes 7a and 7b are formed on the left and right sides of the upper surface of the sealing substrate 8.

One end of the internal electrodes 7a and 7b is the left side of the substrate 8, respectively.
It is exposed on the right side.

In the actual mass production process, these substrates 2, 5.8 have a wide area and are cut into predetermined dimensions after being laminated.

The substrates 2, 5.8 prepared in this way are fixed to each other by the applied adhesive 12 at a distance so as not to come into direct contact with each other, thereby forming a sealed vibration space (see FIG. 3). Internal electrodes 6a, 6b, 7a, on the side where a sealed vibration space is formed by the piezoelectric substrate 2 and the sealing substrate 5.8
7b is provided.

FIG. 2 shows the appearance of the resonator 1. Input and output electrodes (A) are provided at the left and right ends and the center of the oscillator 1, respectively.

(B) and a common electrode (C) are formed. electrode(
A) is connected to an extraction electrode 4a and internal electrodes 6a and 7a. The other electrode (B) has an extraction electrode 4.
b and internal electrodes 6b and 7b are connected. Further, an electrode (C) is formed in a band shape at the center of the oscillator 1. These electrodes (A), (B), and (C) are used as electrodes for attachment to a printed wiring board, etc., and also have a function as capacitive electrodes. That is, electrode (A)-
A capacitance C1 is formed between electrodes (B) and (C).
) A capacitance C2 is formed between the two. In addition, a common electrode (
A capacitor is formed by C), the internal electrodes 6a, 6b, 7a, 7b, and the sealing substrate 5.8, and static electricity is formed between the electrode (C) and the internal electrode 68 and between the electrode (C) and the internal electrode 7a. Composite capacitance C that combines capacitances Ca' and Ca''
a, 'It electrode (C) - internal electrode 6b and electrode (C)
- Capacitance Cb', Cb" formed between internal electrodes 7b
A composite capacitance cb is obtained by combining the . Therefore, a large capacitance can be obtained without narrowing the gap between the external electrodes, so that there is no risk of migration, solder bridges, etc., and a component with high electrical reliability can be obtained.

Further, even if the external dimensions of the components are reduced, a practically sufficient capacity can be obtained. Note that the obtained capacity is between electrodes (A)-(C)
and the gap between electrodes (B) and (C), the electrode area of internal electrodes 6a, 6b, 7a, and 7b, and the sealing substrate 5
．． 8 thickness etc. will be hunt rolled.

The oscillator 1 having the above configuration has a circuit similar to the electric circuit shown in FIG. A resonator is inserted between the input and output electrodes (A”) and (B), and the capacitances C1 and C2 and the combined capacitance C
a and Cb are input and output electrodes (A) and common electrode (C), respectively.
It is inserted between the input/output electrode (B) and the common electrode (C).

[Second Example, Figures 5 and 6] FIG. 5 shows a vertical cross-sectional view of the three-terminal oscillator 15.

This oscillator 15 is composed of one piezoelectric substrate and two sealing substrates. The piezoelectric substrate 16 has vibrating electrodes 17a and 17b formed at the center of its upper and lower surfaces. Further, the vibrating electrode 17a is connected to an extraction electrode 18a formed on the left side of the piezoelectric substrate 16, and the vibrating electrode 17b is connected to an extraction electrode 18b formed on the right side of the piezoelectric substrate 16.

A dielectric substrate is used as the sealing substrate 19, 22. As shown in FIG. 6, a circular vibration space forming recess 19a is provided at the center of the upper surface of the sealing substrate 19, and an internal electrode 20 having an annular pattern is formed around the recess 19a.

One end of the internal electrode 20 is exposed on the right side of the substrate 19.

Similarly, a vibration space forming recess 22a is provided at the center of the lower surface of the sealing substrate 22, and an internal electrode 23 having an annular pattern is formed around the recess 22a. One end of the internal electrode 23 is exposed on the left side of the substrate 22.

The substrates 16, 19, 22 are fixed by an applied adhesive 27 to form a sealed vibration space. At this time, the internal electrodes 20 and 23 are the extraction electrodes 18a and 23, respectively.
18b. However, the internal electrodes 20.23 and the extraction electrodes 18a, 18b do not necessarily need to be in contact with each other.

Input/output electrodes (A), (B) and a common electrode (C) are formed at the left and right ends and the center of the oscillator 15, respectively. On the other hand, the input/output electrode (A) has a lead electrode 18a.
and internal electrodes 23 are connected. The extraction electrode 18b and the internal electrode 20 are connected to the other input/output electrode (B). Furthermore, a common electrode (C) is formed in the shape of a strip at the center of the oscillator 15.

The obtained oscillator 15 has a common electrode (C) and an internal electrode 20.
．． 23 and the sealing substrates 19 and 22 form a capacitor. Therefore, the oscillator 15 has a capacitance C1 between electrodes (A) and (C), a capacitance C2 between electrodes (B) and (C),
Further, capacitance Ca between the electrode (C) and the internal electrode 23,
A capacitance of 0 is formed between the pole (C) and the internal electrode 20.

Therefore, the oscillator 15 has a circuit similar to the electrical circuit shown in FIG.

[Third Embodiment, Section 7] FIG. 7 is a vertical sectional view showing an oscillator 30 according to a third embodiment of the present invention. The piezoelectric substrate 31 has vibrating electrodes 32 on the front and back surfaces.
a, 32b are formed. Vibrating electrode 32a.

One end of 32b wraps around to the opposite surface.

The dielectric case 33 is divided into two parts: a storage container 34 and a sealing lid 40. The storage container 34 has a recess 34a, and cutouts 35.35 are provided on the left and right side walls of the recess 34a, and the piezoelectric substrate 31 is stored horizontally in a horizontally long state using the cutouts 35.35 as a guide. . Steps 36, 36 are provided on both left and right sides of the bottom surface of the recess 34a, and support both ends of the piezoelectric substrate 31 to form the vibrating electrode 32a.

The vibrating portion of 32b is prevented from coming into contact with the bottom wall surface. Conductive patterns 37 and 38 are formed on both left and right sides of the storage container 34, at the notches 35 and 35, and on both left and right sides of the bottom surface of the recess 34a by a method such as sputtering or vapor deposition. Furthermore, a common electrode (C) is formed on the outer surface of the central portion of the storage container 34. Vibrating electrodes 32a, 3
2b is a conductive pattern 37, 38 via solder 39, 39.
Connect to. The sealing lid 40 is fixed to the open end of the storage container 34 with an adhesive, and the piezoelectric substrate 31 is housed in the vibration space sealed by the storage container 34 and the sealing lid 40.

The thus obtained oscillator 30 has a conductive pattern 37°3.
8, the internal electrode portion 3 formed on the bottom surface of the recess 34a
7a, 38a, the common electrode (C), and the storage container 34 form a capacitor. Also conductive pattern 37.38
Of these, the input/output electrodes (A) and (B) that are completely formed on the outer surface of the left and right ends of the storage container, together with the common electrode (C), function as capacitive electrodes and can be attached to printed wiring boards, etc. as electrodes. It has the following functions. Therefore, the oscillator 30 has a capacitance C1 between the electrode part (A) and the electrode (C), a capacitance C2 between the electrode part (B) and the electrode (C), and a capacitance C2 between the electrode part (B) and the electrode (C).
C) - electrostatic capacitance Ca between the internal electrode part 37a, v: pole (
C) A capacitance Cb is completely formed between the internal electrode portion 38a and the internal electrode portion 38a. Therefore, the oscillator 30 has a circuit similar to the electrical circuit shown in FIG.

[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.

In the first and second embodiments, a piezoelectric resonator is shown in which internal electrodes are formed on both of the two sealing substrates, but if the necessary capacitance can be obtained, one sealing substrate may be used. It is also possible to form internal electrodes only on the surface.

Furthermore, in the embodiment described above, an adhesive is used to fix the dielectric sealing member, but it may be fixed using means such as caulking.

Further, the arrangement and shape of the internal electrodes formed on the sealing member are arbitrary. For example, the internal electrodes 20 of the second embodiment are
Internal electrode 20A or 2 shown in FIG. 8 or 9
It may be 0B.

λriOS+ In the present invention, the capacitance is increased because the capacitance is obtained between the input/output electrode and the common i electrode and between the common electrode and the internal electrode.

Therefore, without narrowing the gap between external electrodes,
A piezoelectric resonator with a built-in capacitor that has a large capacitance, is free from migration, solder bridges, etc., and has high electrical reliability can be obtained.

Conversely, in the case of a piezoelectric resonator with a built-in capacitor having the same external dimensions and the same capacitance, the gap between the capacitor electrodes can be made wider, and reliability against migration, solder bridging, etc. can be improved.

Furthermore, even if the external dimensions of the components are reduced, a practically sufficient capacity can be obtained.

[Brief explanation of drawings]

1 to 4 show a first embodiment of a piezoelectric resonator according to the present invention, in which FIG. 1 is an exploded perspective view, FIG. 2 is a perspective view showing the external appearance, and FIG. 3 is a second embodiment. FIG. 4 is a vertical cross-sectional view taken along line X-X'' of FIG. 4, and is an electrical equivalent circuit diagram. 5 and 6 show a second embodiment of the piezoelectric resonator according to the present invention, FIG. 5 is a vertical sectional view, and FIG. 6 is a plan view of the dielectric substrate viewed from the internal electrode forming surface side. It is a diagram. FIG. 7 is a vertical sectional view showing a third embodiment of the piezoelectric resonator according to the present invention. 8 and 9 are plan views showing modified examples of the dielectric substrate shown in FIG. 6. FIG. FIG. 10 is an oscillation circuit diagram. Figure 11,
12 and 13 show technology prior to the present invention, FIG. 11 is an exploded perspective view of a piezoelectric resonator, FIG. 12 is a perspective view showing the external appearance of the piezoelectric resonator, and FIG. x-x'
FIG. 1... piezoelectric resonator (oscillator), 2... piezoelectric substrate,
3a, 3b... Vibrating electrode, 5... Dielectric sealing member (sealing substrate), 6a, 6b, 7a, 7b... Internal electrode, 8... Dielectric sealing member (sealing substrate) ), 15・
...Piezoelectric resonator (oscillator), 16...Piezoelectric substrate, 1
7a, 17b... Vibration electrode, 19... Dielectric sealing member (sealing substrate), 20.2OA, 20B... Internal electrode, 22... Dielectric sealing member (sealing substrate), 23・
... Internal electrode, 30 ... Piezoelectric resonator (oscillator), 31
... piezoelectric substrate, 32a, 32b... vibrating electrode,
33...Dielectric sealing member (sealing case), 37a, 3
8a --- Internal electrode, (A), (B) --- Input/output electrode, <C> --- Common electrode, Ca, Ca', Ca'', c
b, cb'. cb"...Capacity.

Claims (1)

[Claims] 1. A laminate is formed of a piezoelectric substrate provided with a vibrating electrode and a dielectric sealing member that seals the piezoelectric substrate to form a vibration space, and an input/output electrode and a common electrode are provided on the outer surface of the laminate. In the piezoelectric resonator provided with the above, an internal electrode connected to the input/output electrode is provided on the vibration space forming side surface of the sealing member, and the input/output electrode and the common electrode are connected to each other, and the internal electrode and the common electrode are connected to each other. A piezoelectric resonator characterized by forming a capacitive part.