JPH03165614A - Piezoelectric component - Google Patents

Abstract

PURPOSE:To eliminate spurious radiation due to the vibration at a load capacitive component without complicated manufacture process by forming an energy confinement vibration electrode to both major faces of a piezoelectric substrate and providing a capacitor electrode respectively to both the major faces of the piezoelectric substrate in the vicinity of the vibration electrode. CONSTITUTION:A load capacitor is constituted by capacitor electrodes 3a, 3b and vibration electrodes 2a, 2b provided on a same major side of a piezoelectric substrate 1 close to each other. Even when piezoelectric vibration takes place between the capacitor electrodes 3a, 3b and the vibration electrodes 2a, 2b, the vibration is generated at the same resonance frequency and anti- resonance frequency as those of the piezoelectric vibration between the vibration electrodes 2a, 2b and no spurious vibration appears even when the vibration of the both is superimposed. Thus, even when the piezoelectric substrate 1 subjected to polarization processing entirely is employed, no spurious vibration is caused different from a conventional piezoelectric substrate. Furthermore, the manufacture process is simplified and the piezoelectric component of built-in load capacitor is manufactured inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a piezoelectric component with a built-in load capacitor, which includes a resonator and a pair of load capacitors.

[Background Art and Its Problems] Figure 8 is a circuit diagram of a basic oscillation circuit using an inverting amplifier A, in which the inverting amplifier A, feedback resistor Rt, and resonator X are connected in parallel. Both ends of the load capacitance C5-C
, +. As an electronic component for use in such an oscillation circuit, a piezoelectric component with a built-in load capacitor (the part within the broken line in FIG. 6), in which a load capacitor is connected to both ends of a resonator, has conventionally been provided.

FIG. 7 shows a vibrating element 51 used in a conventional piezoelectric component with built-in load capacity. These are energy trapping type vibrating electrodes 53a located at the center of both mold surfaces of the ceramic piezoelectric substrate 52 and facing each other.

53b, and the lead terminals drawn out from these vibrating electrodes 53a, 53b are attached to external lead-out electrodes 54a,
5" 4b is arranged at the end of the piezoelectric substrate 52, and a capacitive type g155a, 55b is formed on the main surface on the opposite side facing each external extraction electrode 54a, 54b, and each external extraction electrode 54a, 54b A lead terminal is soldered to each of the capacitors 55a and 55b, and a ground terminal is soldered to both capacitors 55a and 55b.A resonator External lead electrodes 54a, 5 facing each other with the substrate 52 in between
4b and the capacitance electrodes 55a, 55b, the load capacitance C1, C
2 are configured.

The method of manufacturing the vibrating element 51 shown in FIG.
One is the simple manufacturing method shown in FIGS. 8(a) to (cl), and the other is the manufacturing method shown in FIGS. 10(a) to (g).

In the manufacturing method shown in FIGS. 8(a) to 8(d), first, an electrode film 56 is formed by vapor deposition or the like on the entire bidirectional surface of the piezoelectric substrate 52 of the ceramic product to be fired. A polarization voltage is applied to the piezoelectric substrate 52 to perform polarization treatment on the entire piezoelectric substrate 52 (FIG. 2(b)). After that, a resist film 57 is printed on the electrode film 56 to form a pattern for obtaining a vibrating electrode, an external lead electrode, a capacitor electrode, etc. (FIG. (C)), and the resist film 57 of the electrode film 56 is etched with an etching solution. The exposed portion from the resist film 57 is removed by etching, and then the resist film 57 is removed.
Vibrating electrodes 53a are formed on both main surfaces of the piezoelectric substrate 52.
+53b-External extraction electrodes 54a, 54b.

Capacitive electrodes 55a, 55b, etc. are formed, and the vibration element 6
1 ((d) in the same figure).

However, in vibrating elements manufactured using this method, the entire piezoelectric substrate is polarized, so slight vibrations occur even between the capacitive electrodes that make up the load capacitance and the external lead electrodes. (Piezoelectric vibration) was generated, and the vibration could not be completely suppressed even with the solder that fixed the lead terminals. Moreover, the polarization process of the piezoelectric substrate is not necessarily uniform over the entire piezoelectric substrate, the capacitive electrode part is located away from the vibrating electrode part, and the solder on the capacitive electrode acts as a mass load, so the load capacitive part The resonant frequency of the generated vibration deviates from the resonant frequency of the vibration of the resonator part, and as shown in the frequency characteristics of Fig. 9, the most important resonant frequency fr of the resonant characteristics
The spurious (or ripple) Z appeared between the anti-resonant frequency fa and the anti-resonant frequency fa. Due to this spurious excitation, when operated as an oscillation element, for example, the oscillation frequency may change abnormally or oscillation may stop, resulting in a decrease in performance.

In addition, other manufacturing methods shown in FIGS. 10(a) to (g) are as follows:
An electrode film 58 is formed on the entire bidirectional surface of the piezoelectric substrate 52 by vapor deposition or the like.
A resist film 59 is printed on top of the electrode film 58 to form the same pattern as the vibrating electrode (see FIG. 5(b)), and this is etched to form the resist film 5.
The electrode film 58 exposed from the electrode film 9 is removed, the resist film 59 is peeled off, and a polarization electrode 60 is provided at the position where the vibrating electrode is formed (FIG. 2(C)), and a polarization voltage is applied to this polarization electrode 80. Then, the piezoelectric substrate 52 is partially polarized (FIG. 4(d)).

After that, the polarization electrode θO is removed, and the electrode film 61 is again formed on the entire bidirectional surface of the piezoelectric substrate 52 by vapor deposition or the like.
e)), a resist film θ2 is printed on this electrode film 61 to form a pattern for obtaining a vibrating electrode, an external lead electrode, a capacitor electrode, etc. (f)), and the electrode film e1 is etched using an etching solution. The exposed portions of the resist film 82 are removed by etching, and then the resist film 62 is peeled off, and vibration electrodes 53a, 53b, external lead electrodes 54a, 54b, capacitor electrodes 55a, 55b, etc. are formed on both main surfaces of the piezoelectric substrate 52. , the vibration element 51 is being manufactured ((g) in the same figure).
).

If manufactured by the method shown in FIGS. 10(a) to (g), the piezoelectric substrate is partially polarized only at the vibrating electrodes and not at the capacitive electrodes, so the load capacitance can be reduced. Although piezoelectric vibration does not occur between the capacitive electrode and the external lead-out electrode, and spurious vibration does not occur, there is a problem in that the number of manufacturing steps is significantly increased.

[Problems to be Solved by the Invention] The present invention has been made in view of the drawbacks of the conventional examples described above, and its purpose is to solve the problem of complicating the manufacturing process in piezoelectric components with built-in load capacitance. The object of the present invention is to eliminate spurious noise caused by vibration in a load capacitance portion without using a partially polarized piezoelectric substrate.

Means for Solving Problem C] Therefore, the piezoelectric component of the present invention is a piezoelectric component with built-in load capacitance, which has load capacitances at both ends of a resonator, and traps energy on both main surfaces of the piezoelectric substrate. A type of vibrating electrode is formed, capacitive electrodes are provided on both main surfaces of the piezoelectric substrate in the vicinity of these vibrating electrodes, and an external lead electrode drawn from the vibrating electrode and an external lead electrode drawn from the capacitive electrode are connected to the piezoelectric substrate. A resonator is arranged between the two vibrating electrodes, one load capacity is constituted by the vibrating electrode and the capacitive electrode formed on one main surface, and the vibrating electrode and the capacitive electrode are formed on the other main surface. It is characterized in that the other load capacitor is formed by a capacitor electrode.

[Function] In the present invention, since the load capacitance is constituted by the capacitive electrode and the vibrating electrode that are provided close to each other on the same main surface of the piezoelectric substrate, even if piezoelectric vibration occurs between the capacitive electrode and the vibrating electrode, Vibration occurs at the same resonant frequency and anti-resonant frequency as the piezoelectric vibration between the vibrating electrodes, and even if the two vibrations overlap, they do not appear as spurious vibrations. Also, unlike the conventional example, spurious vibrations do not occur.

Furthermore, since a piezoelectric substrate that is entirely polarized can be used, the manufacturing process is simplified, and a load-accommodating, indoor-type piezoelectric component can be manufactured at low cost.

[Example code] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

What is shown in FIG. 1 is a vibrating element θ, in which a conductor pattern is formed on the surface of a ceramic piezoelectric substrate l by a thin film forming technique such as vapor deposition.

That is, vibrating electrodes 2a and 2b are formed in the center of both main surfaces of the piezoelectric substrate l so as to face each other, and arc-shaped electrodes 2a and 2b are formed in the vicinity of the vibrating electrodes 2a and 2b so as to surround the vibrating electrodes 2a and 2b. Capacitive electrode 3a.

3b is provided. Further, in the peripheral part of the piezoelectric substrate 1, an external lead electrode 5a is drawn out from the capacitive electrodes 3a and sb via lead parts 7a and 7b.

Vibrating electrodes 2a, 6b are arranged to face each other on both main surfaces, and vibrating electrodes 2a, 2b are connected to both sides of the externally drawn electrodes 5a, 5b via lead parts 8a, 8b so as not to face each other.
External lead electrodes 4a and 4b drawn out from 2b are provided. This vibrating element 6 is manufactured through a process similar to the conventional manufacturing method shown in FIG. 8, and is polarized in the thickness direction over the entire piezoelectric substrate 1. And vibrating electrodes 2a, 2b on both main surfaces
A resonator X is constructed between the vibrating electrodes 2 on the same main surface.
Load capacitances C+ and Cz are constituted by a, 2b and capacitive electrodes 3 a + 3 b.

As shown in FIG.
A ground terminal θ is attached to terminal b for common connection, and lead terminals 10 and 11 are attached to external extraction electrodes 4a and 4b, respectively. Thereafter, as shown in FIG.
A piezoelectric component is manufactured by coating the This piezoelectric component becomes a piezoelectric component with a built-in load capacitance that has both circuits equal to the portion within the broken line in FIG.

In such a piezoelectric component, since the load capacitance C1+C3 and the resonator X are arranged close to each other, the vibrating electrode 2
Also between the vibrating electrodes 2a, 2b and the capacitive electrodes 3a, 3b,
It vibrates at the same resonant frequency fr and anti-resonant frequency fa as between 2b, and even if the frequency characteristics of both are superimposed, no spurious occurs, and the spurious between the resonant frequency and the anti-resonant frequency can be eliminated. As shown in the figure, it is possible to obtain good frequency characteristics without spurious signals. Further, since a piezoelectric substrate whose entire structure is polarized can be used, the vibrating element can be manufactured by a manufacturing method similar to that shown in FIG. 8, and manufacturing can be simplified.

[Effects of the Invention] According to the present invention, the resonant frequency and anti-resonance frequency of the vibration generated in the load capacitance portion can be made equal to the vibration of the resonator portion, and the vibration generated in the load capacitance portion can be made equal to the frequency of the resonator. It is possible to prevent spurious vibrations from appearing in the characteristics, and it is possible to obtain good resonance characteristics. Furthermore, since a piezoelectric substrate whose entire structure is polarized can be used, the manufacturing process can be extremely simplified, and a piezoelectric component with internal load capacity can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a vibrating element according to an embodiment of the present invention, FIG. 2 is a perspective view of the same terminal attached afterward, FIG. 3 is a sectional view of a piezoelectric component covered with an exterior resin, and FIG. Figure 5 is a graph showing the impedance and phase frequency characteristics of the same piezoelectric component as above, Figure 6 is a circuit diagram of an oscillation circuit, and Figure 7 is a conventional piezoelectric component with built-in load capacitance. A perspective view showing the vibration element of FIG. 8(a) (
b) (c) (d) are explanatory views showing one manufacturing method of the vibrating element shown in Fig. 7, and Fig. 9 is an explanatory diagram showing one manufacturing method of the vibrating element shown in Fig. 8 (a) (b) (
c) Graphs showing the impedance and phase frequency characteristics of the vibration/vibration element manufactured by the manufacturing method of (d), Fig. 10 (a) (b) (c) (d) (e
) (f) (g) are explanatory diagrams showing another method of manufacturing the vibrating element of FIG. 7; X... Resonators C1, C2... Load capacitance 1... Piezoelectric substrates 2a, 2b... Vibration electrodes 3a, 3b... Capacitive electrodes 4a, 4b... External extraction electrodes 5a, 5b...・External extraction electrode

Claims (1)

[Claims] (1) A piezoelectric component with built-in load capacitance, which has a load capacitance at each end of a resonator, in which energy-trapping type vibrating electrodes are formed on both main surfaces of a piezoelectric substrate, and the piezoelectric substrate is placed near these vibrating electrodes. Capacitive electrodes are provided on both main surfaces of the piezoelectric substrate, and an external extraction electrode drawn from the vibrating electrode and an external extraction electrode drawn from the capacitive electrode are arranged on the outer edge of the piezoelectric substrate, and a resonator is formed between both the vibrating electrodes. A piezoelectric device characterized in that one load capacity is formed by a vibrating electrode and a capacitive electrode formed on one main surface, and the other load capacity is formed by a vibrating electrode and a capacitive electrode formed on the other main surface. parts.