JPS62203411A - Capacitor built-in type piezoelectric vibrator - Google Patents

Abstract

PURPOSE:To attain the miniaturization and cost reduction by using a common electrode of a capacitor as a supporting base of a piezoelectric vibrator and using an individual layer as a fixed terminal of the piezoelectric vibrator. CONSTITUTION:In a composite resonator of 3-terminal including at least one piezoelectric vibrator and two capacitors, the common electrode of the capacitor as the supporting base and the individual electrode of the capacitor formed via the dielectric layer on the electrode is used as the fixed terminal of the piezoelectric vibrator. A thick film capacitor is formed on the alumina base by the screen print method and in the resonator mounting the piezoelectric vibrator to the electrode of the thick film capacitor, the miniaturization and cost reduction are attained by eliminating the alumina base. That is, in forming the common electrode with a sufficient mechanical strength, the alumina base is removed.

Description

[Detailed Description of the Invention] [Summary] Instead of mounting two capacitors and one piezoelectric vibrator on a ceramic substrate, a capacitor is formed using a common electrode as a supporting substrate, and the capacitors are placed in opposite positions with a dielectric layer in between. A three-terminal piezoelectric vibrator with a built-in capacitor, in which the individual electrodes are the fixed positions of the piezoelectric vibrator.

[Industrial application field]

The present invention relates to improvements in piezoelectric vibrators with built-in capacitors.

A piezoelectric vibrator with a built-in capacitor is used in microcomputers as a clock signal generator in combination with an IC.

Figure 4 shows this equivalent circuit, which is a three-terminal composite resonator consisting of one piezoelectric vibrator 1 and two capacitors 2.3, where the piezoelectric vibrator 1 is lithium niobate (LiN).
b O3), lithium tantalate (LiTaO3)
Many are made using piezoelectric crystals such as.

The capacitors 2 and 3 are made of barium titanate (BaTi).
Many ceramic capacitors whose main component is O:+) are used.

FIG. 5 shows, as an application example, a clock oscillation circuit using a piezoelectric resonator (hereinafter referred to as a resonator) 4 with a built-in capacitor. An oscillation circuit is configured.

[Conventional technology]

Conventional resonators are formed with unique configurations depending on the manufacturer.

For example, a ceramic chip capacitor consisting of two capacitors and a piezoelectric vibrator are welded to lead terminals from both sides, and the lead terminal is also taken out from the midpoint of the two capacitors and molded in resin to create a three-terminal structure. be.

FIG. 6 shows an example of forming a thick film capacitor on an alumina substrate using screen printing technology, in which a conductive paste is screen printed on an alumina (α-^jl!zo:+) substrate 7. A common electrode 8 is formed by patterning, and a dielectric layer 9 is formed by screen printing a dielectric paste thereon.
Two capacitors are formed by forming individual electrodes 10 by screen printing a conductive paste thereon.

A resonator is completed by mounting a piezoelectric vibrator l using this individual electrode 10.

Note that lead terminals 11.
12.13 has been drawn out.

The resonator has such a configuration and is manufactured by molding the piezoelectric vibrator 1 with a resin mold while protecting the top of the piezoelectric vibrator 1 with a cap made of ceramic or the like.

However, since there is a need for further miniaturization and cost reduction, it has been desired to put into practical use improved products that meet these demands.

[Problem that the invention seeks to solve]

As described above, the resonator is composed of one piezoelectric vibrator and two capacitors, but the challenge is to put into practical use a new configuration that is compact and can reduce costs.

[Means for solving problems]

The above problem is solved in a three-terminal composite resonator comprising at least one piezoelectric vibrator and two capacitors, in which the piezoelectric vibrator uses the common electrode of the capacitor as a support substrate,
This can be realized by a capacitor built-in piezoelectric vibrator characterized in that the individual electrodes of a capacitor formed on the electrodes via a dielectric layer are configured as fixed terminals of the piezoelectric vibrator.

[Effect]

The present invention provides a resonator in which a thick film capacitor is formed on an alumina substrate by a screen printing method, and a piezoelectric vibrator is attached to the electrodes of this thick film capacitor. This realizes cost reduction.

In other words, in the past, an alumina substrate was used as a support and a resonator was formed on the support by a screen printing method, but the present invention focuses on the fact that the common electrode is formed over the entire area of the substrate. By forming the common electrode with sufficient mechanical strength, the alumina substrate can be removed.

In this case, there are various methods for forming the capacitor as described below.

■ A dielectric layer is created by screen-printing a ferroelectric paste mainly composed of BaTi01 over the entire area above the common electrode, and then a conductive paste is screen-printed over a certain area on top of this to form two layers. How to make a capacitor.

■ A method of creating two capacitors by screen-printing ferroelectric paste on the common electrode only at the capacitor formation position, and forming a fully bent electrode that also serves as a lead terminal on top of this.

■ A method of making two capacitors by screen printing ferroelectric paste only at the capacitor forming position on the common electrode, and then screen printing conductive paste on top of this.

There is.

According to the present invention, a capacitor is manufactured in this manner, and a piezoelectric vibrator is welded to the individual electrodes.

〔Example〕

Example 1: FIG. 1 is a front view (A), a plan view (B), and a perspective view (C) of a piezoelectric vibrator with a built-in capacitor according to the present invention.

That is, as the common electrode 15, a thin plate of nickel (Ni) plated iron (Fe) having a thickness of 0.8 In is used, and the size thereof is 10×4.5 mm.

A dielectric paste containing BaTi0= as a main component is screen printed over the entire area above this common electrode 15.
A dielectric layer 16 having a thickness of about 200 μm was formed by firing at 0°C.

The dielectric constant of this dielectric material is 100.

Next, a conductive paste is screen printed on top of this and then fired to form individual electrodes 17, which increases the capacitance by 2.
A 0 pF capacitor was formed.

Next, the lead terminal 1 is placed on the common electrode 15 and the individual electrode 17.
After soldering 8, 19 and 20, the piezoelectric vibrator 1 was welded to the lead terminal 19 and 20 of the individual electrode 17, thereby completing a resonator.

Embodiment 2: FIG. 2 is a front view (A), a plan view (B), and a perspective view (C) of a piezoelectric vibrator with a built-in capacitor according to the present invention.

Here, the difference from Embodiment 1 is that the lead terminal 21 is integrally stamped with the common electrode 22, and the individual electrodes 23 are also integrally molded with the lead terminals 24 and 25. It is also a Ni-plated Fe thin plate with a thickness of 0.8 mm.

The manufacturing method for this capacitor is to screen print a dielectric paste on the capacitor forming position on the common electrode 22, then glue the individual electrodes 23, and then pressurize the capacitor in the atmosphere.
A 20 pF capacitor was made by firing at 00°C.

Thereafter, a resonator was completed by welding the piezoelectric vibrator 1 onto the individual electrode 23.

Embodiment 3: FIG. 3 is a front view (A), a plan view (B), and a perspective view (C) of a piezoelectric vibrator with a built-in capacitor according to the present invention.

Here, the difference from Example 2 is that the individual electrodes 26 of the capacitor are formed by the screen printing method as in Example 1, and after soldering lead terminals 27 and 28 thereon, piezoelectric vibration The fabrication method was the same as that described in Example 1.2.

〔Effect of the invention〕

According to the present invention, it is not necessary to use alumina porcelain as a substrate, which makes it possible to reduce costs, and since the alumina substrate, which occupies most of the device volume, is eliminated, the resonator can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a front view (A), plan view (B), and perspective view (C) of a piezoelectric vibrator with a built-in capacitor according to the present invention, and FIG. 2 is a front view of a piezoelectric vibrator with a built-in capacitor according to the present invention. FIG. 3 is a front view (A), a plan view (B), and a perspective view (C) of a piezoelectric vibrator with a built-in capacitor according to the present invention. ), Figure 4 is an equivalent circuit of a piezoelectric resonator with a built-in capacitor, Figure 5 is a clock oscillation circuit, and Figure 6 is a front view of a conventional piezoelectric resonator with a built-in capacitor (
A) and a plan view (B). In the figure, 1 is a piezoelectric vibrator, 2.3 is a capacitor, 4 is a resonator, 7 is an alumina substrate, 8, 15.
22 is a common snow shovel, 9,16. are dielectric layers, 10, 17
, 23.26 are individual electrodes, 11.12.13.18.19, 20, 21, 24.2
5 is a lead terminal.

Claims (4)

[Claims] (1) In a three-terminal composite resonator comprising at least one piezoelectric vibrator and two capacitors, the piezoelectric vibrator has a common electrode of the capacitor as a support substrate, and a dielectric layer is placed on the electrode. A piezoelectric vibrator with a built-in capacitor, characterized in that the individual electrodes of the capacitor formed by the capacitor are configured as fixed terminals of the piezoelectric vibrator. (2) A piezoelectric device with a built-in capacitor according to claim 1, wherein the two capacitors are formed by forming a common electrode on one side of a dielectric layer and patterning individual electrodes on the other side. vibrator. (3) A claim characterized in that a dielectric layer is individually patterned on a metal electrode that serves as a common electrode for two capacitors, and a lead terminal is mounted on the dielectric layer as an electrode of the capacitor. A piezoelectric vibrator with a built-in capacitor as described in item 1. (4) A dielectric layer is individually patterned on a metal electrode that serves as a common electrode for two capacitors, and an individual electrode is patterned on the dielectric layer. The piezoelectric vibrator with a built-in capacitor as described in item 1.