JPH0722894A - Ceramic oscillation element and piezoelectric oscillator using the same - Google Patents

Abstract

PURPOSE:To provide a ceramic oscillation element comprised by forming conductor layers on the upper and lower planes of a piezoelectric ceramic element body in which oscillation stop and characteristic deterioration due to use environment, etc., can be prevented from occurring due to working environment by constituting a dielectric layer of two layers of chlome-gold or nickel chlomium alloy-gold. CONSTITUTION:The conductor layer 3 consisting of the two layers of a chrome layer 3a (for example, of layer thickness of around 0.3mum) and a gold layer 3b (for example, of layer thickness of around 0.3mum) is provided on the upper plane of a plate shape piezoelectric ceramic element body 2 extending over a center part from one end part and the conductor layer 4 consisting of the two layers of a chrome layer 4a and a gold layer 4b similarly as the conductor layer 3 is provided on the lower surface of the piezoelectric ceramic element body 2 extending over the center part from the other end part of the piezoelectric ceramic element body and so as to plane-polymerize a part of it at the upper and lower planes of the center part of the conductor layer 3 provided at the upper plane and the piezoelectric ceramic element body 2 in the ceramic oscillation element 1. Therefore, no migration occurs in the conductor layers 3, 4, and the ones hard to be oxidized can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic oscillator and a piezoelectric oscillator using the same as an oscillator.

[0002]

2. Description of the Related Art For example, a surface mount type piezoelectric oscillator is
As shown in FIG. 4, the base substrate 1 made of ceramic or the like
0, terminal electrodes 11 formed on both ends of the base substrate 10, and a ceramic oscillator 13 having both ends connected to the terminal electrode 11 with a conductive paste 12 at a predetermined distance from the base substrate 10. And a cap 14 that covers the ceramic oscillation element 13 and is attached to the peripheral portion of the base substrate 10 via an insulating layer such as glass frit.

Conventionally, as shown in FIGS. 5 and 6, the ceramic oscillation element 13 used in the above-described piezoelectric oscillator has silver or copper-silver on the upper and lower surfaces of a plate-shaped piezoelectric ceramic body 15. Conductive layer 1 composed of an alloy or two layers of copper-silver
Reference numerals 6 and 17 are provided in such a manner that a part of the piezoelectric ceramic body 15 is superposed in plan view in the central portion.

[0004]

However, although the conventional ceramic oscillating device as described above is hermetically sealed by being packaged with a cap or the like in the piezoelectric oscillator, it becomes hot and moisture When it penetrates into the package or is used in a high temperature or high humidity environment, silver, copper, or a copper-silver alloy, which is a component of the conductive layer of the ceramic oscillation element, can be absorbed inside and / or inside the piezoelectric ceramic body. Alternatively, there is a problem in that migration occurs on the side surface, which leads to deterioration of the characteristics of the ceramic oscillation element and further causes oscillation stop due to short circuit between the conductive layers on the upper and lower surfaces of the ceramic oscillation element or the opening due to disappearance of the conductive layer.

On the other hand, the silver layer or the copper-silver alloy layer, which is the surface layer of the conductive layer in the conventional ceramic oscillating device, may be easily oxidized during operation under high temperature or high humidity, resulting in poor conduction.

When the conductive layer is composed of two layers of copper-silver, copper or silver migrates at the interface between the copper layer and the silver layer, and the conduction state changes when a voltage is applied to the conductive layer. There was also a risk that characteristic deterioration would occur.

The present invention solves the above problems and does not cause oscillation stop due to a short circuit defect between the conductive layers on the upper and lower surfaces of the ceramic oscillation element or an open defect caused by disappearance of the conductive layer, and characteristic deterioration due to use environment. It is an object of the present invention to provide a piezoelectric oscillator having excellent reliability and environmental resistance.

[0008]

As a result of intensive studies to achieve the above object, the present inventor has found that when the conductive layer in a ceramic oscillation element is a double layer of chromium-gold or nickel-chromium alloy-gold. Found that migration of the conductive layer did not occur.

That is, the present invention is a ceramic oscillating device having a conductive layer formed on the upper surface and the lower surface of a piezoelectric ceramic body, wherein the conductive layer comprises two layers of chromium-gold or nickel-chromium alloy-gold. The present invention relates to a ceramic oscillating device.

Further, according to the present invention, there is provided a ceramic oscillating device comprising a piezoelectric ceramic body and conductive layers formed on the upper and lower surfaces thereof, wherein the conductive layer comprises three layers of chromium-nickel-gold. The present invention relates to a ceramic oscillation element.

Further, the present invention also includes a piezoelectric oscillator using the above ceramic oscillator.

[0012]

Since the gold layer is formed on the piezoelectric ceramic body through the chromium layer or the nickel-chromium alloy layer to provide the conductive layer, migration of the components of the conductive layer into the piezoelectric ceramic body is prevented. It can be resolved.

Further, gold, which is the surface layer of the conductive layer, is an extremely stable substance and is therefore unlikely to be oxidized, so that it is possible to prevent characteristic deterioration due to poor conduction.

Further, when the conductive layer is composed of three layers of chromium-nickel-gold, nickel can enhance the bonding force between chromium and gold, and can prevent the diffusion of chromium into gold. Therefore, it is more preferable.

[0015]

EXAMPLES Hereinafter, the features of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

1 and 2 are a plan view and a sectional view of a ceramic oscillating device according to a first embodiment of the present invention. First
The ceramic oscillating device 1 according to the embodiment of the present invention has a chrome layer 3a (for example, a layer thickness 0 .3 μm) and gold layer 3
b (for example, a layer thickness of about 0.3 μm) is provided as two conductive layers 3, and a chromium layer 4 a and a gold layer 4 are provided on the lower surface of the piezoelectric ceramic element body 2 in the same manner as the conductive layer 3.
The conductive layer 4 consisting of two layers of b extends from the other end of the piezoelectric ceramic element body 2 to the central portion thereof, and is formed on the upper surface and the conductive layer 3 provided on the upper surface of the piezoelectric ceramic element body 2 at the central portion. The parts are provided so as to overlap each other in a plan view.

In the first embodiment, the conductive layers 3 and 4 are used.
Similar effects can be obtained by using nickel-chromium alloy layers instead of the chromium layers 3a and 4a.

Next, FIG. 3 shows a sectional view of a ceramic oscillating device according to a second embodiment of the present invention. In the second embodiment, the ceramic oscillating device 5 includes the conductive layers 3 and 4 on the upper and lower surfaces of the ceramic oscillating device 1 of the first embodiment, a chromium layer 6a (for example, a layer thickness of about 0.15 μm), and a nickel layer 6b. (For example, the layer thickness is about 0.15 μm) and the gold layer 6c (for example, the layer thickness is about 0.3 μm) is replaced with the conductive layer 6 having a three-layer structure.

These ceramic oscillators 1 and 5 can be manufactured as follows. First, conductive layers 3, 4 and 6 are formed on the upper and lower surfaces of a ceramic substrate divided into a predetermined size to form a plurality of piezoelectric ceramic elements 2 by a sputtering method, a vapor deposition method or the like, and an etching process is performed. To a predetermined pattern. Examples of the etchant used in the above etching treatment include a cerium ammonium nitrate aqueous solution in the case of a chromium layer or a nickel layer, and a KCN aqueous solution in the case of a gold layer. Next, this is divided into a predetermined size to obtain individual ceramic oscillation elements.

Next, in order to compare the ceramic oscillating devices 1 and 5 of the first and second embodiments with a conventional ceramic oscillating device, a first comparative example using a silver layer as a conductive layer and a copper- Using the second comparative example with two layers of silver, a temperature of 121
A DC 5 V was applied under the conditions of ° C, humidity 100%, and atmospheric pressure 2 atm, and migration rates after 240 hours were compared. The number of samples was 15, respectively. As a result, the number of migration occurrences was 0 (occurrence rate 0%) in the first and second examples, 9 (occurrence rate 60%) in the first comparative example, and 15 (occurrence rate in the second comparative example). Rate 100%)
Met.

From the above results, it can be seen that the ceramic oscillating device of this embodiment is extremely superior to the conventional one.

The ceramic oscillating elements 1 and 5 of the first and second embodiments thus constructed are assembled into a piezoelectric oscillator having the structure shown in FIG. 4, for example.

[0023]

According to the ceramic oscillating device of the present invention, the conductive layer does not cause migration and is hard to oxidize. Therefore, the piezoelectric oscillator of the present invention using this ceramic oscillating element is less likely to cause oscillation stoppage and characteristic deterioration due to short-circuit defects, open defects, etc. of the conductive layer in the ceramic oscillating device, as compared with the conventional piezoelectric oscillator. It has excellent reliability and environmental resistance.

[Brief description of drawings]

FIG. 1 is a plan view showing a ceramic oscillator according to a first embodiment.

FIG. 2 is a sectional view taken along line I-I in FIG.

FIG. 3 is a cross-sectional view showing a ceramic oscillator according to a second embodiment.

FIG. 4 is a cross-sectional view showing the structure of a piezoelectric oscillator.

FIG. 5 is a plan view showing a conventional ceramic oscillator.

6 is a sectional view taken along line II-II in FIG.

[Explanation of symbols]

 1,5 Ceramic oscillation element 2 Piezoelectric ceramic element body 3,4,6 Conductive layer 3a, 4a, 6a Chromium layer 3b, 4b, 6c Gold layer 6b Nickel layer

Claims (3)

[Claims] 1. A ceramic oscillating device comprising a piezoelectric ceramic body having conductive layers formed on an upper surface and a lower surface thereof, wherein the conductive layer comprises two layers of chromium-gold or nickel-chromium alloy-gold. And a ceramic oscillator. 2. A ceramic oscillation element comprising a piezoelectric ceramic body and conductive layers formed on the upper and lower surfaces thereof, wherein the conductive layer comprises three layers of chromium-nickel-gold. . 3. A piezoelectric oscillator using the ceramic oscillator according to claim 1.