JPH05129874A - Crystal oscillator chip - Google Patents

Abstract

PURPOSE:To improve the accuracy and the reliability by providing an insulation film at least onto a plane electrode among the plane electrode and side face electrodes being electrodes of the chip so as to prevent an external gas or dust from being adsorbed by the plane electrode of the crystal oscillation chip. CONSTITUTION:An electrode of a crystal oscillation chip 11 consists of a plane electrode 21 made of a metallic film provided onto a crystal plane and of a side face electrode 31 made of a metallic film provided onto the crystal plane. Moreover, an insulation film 41 is deposited on the plane electrode 21 to prevent adsorption of an external gas or dust. Thus, the adsorption of a gas released from a plug, a case and an adhesives being components of the crystal vibrator onto the plane electrode 21 of the crystal oscillation chip 11 is prevented, resulting that the crystal vibrator with high accuracy is obtained without a characteristic deterioration in the change in the oscillation frequency and an increase in the CI or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure for a crystal oscillator.

[0002]

2. Description of the Related Art One embodiment of a conventional crystal oscillator piece will be described with reference to FIG. FIG. 6 is a sectional view of the vibrating portion of the tuning fork type crystal oscillating piece. The flat electrode 26 made of a metal film provided on the plane of the crystal plate and the side electrode 36 made of a metal film provided in the thickness direction of the crystal plate. The crystal oscillating piece 16 is made to oscillate. Further, after connecting the crystal oscillation piece 16 to the plug 57 shown in FIG. 7, cover the case 67,
It becomes the crystal oscillator 77.

[0003]

However, in the conventional technique, the gas released from the plug and the case is adsorbed on the flat electrode, and as a result, the shift of the oscillation frequency and the crystal impedance (hereinafter abbreviated as CI). And deterioration of characteristics such as increase in

Further, the dust emitted from the plug and the case and the dust emitted during the manufacturing process adhere between the flat electrode and the side electrode, and as a result, the electrodes are short-circuited and oscillation is stopped.

In recent years, crystal oscillators have been used as clock sources for information equipment such as computers and communication equipment such as pagers, and demands for high precision and high reliability are increasing. Among them, the characteristic deterioration such as the shift of the oscillation frequency and the increase of CI and the stop of the oscillation are fatal defects. In particular, stopping oscillation is a serious defect that completely stops the function of a product using a crystal oscillator, and a solution to the problem has been long awaited.

The present invention has been made to solve the above problems. An object of the present invention is to deposit an insulating film on at least a flat electrode of a quartz oscillator piece electrode so that gas is adsorbed to the electrode film from the outside. It is to provide a crystal oscillator piece with high accuracy and high reliability by preventing the above-mentioned phenomenon and further preventing a short circuit between the electrodes even if dust from the outside adheres between the electrodes.

[0007]

The crystal oscillator according to the present invention comprises:
In a crystal oscillation piece having a plane electrode made of a metal film provided on a plane of a crystal plate of a crystal oscillation piece made of one crystal plate and a side electrode made of a metal film provided in a thickness direction of the crystal plate, at least An insulating film is provided on the planar electrode.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the crystal oscillating piece of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of the vibrating portion of the tuning fork type crystal oscillating piece, the electrodes of which are flat electrodes 21 made of a metal film provided on the plane of the crystal plate and metal films provided in the thickness direction of the crystal plate. It is composed of the side electrode 31. further,
An insulating film 41 is deposited on the flat electrode 21 to prevent adsorption of gas and dust from the outside.

The metal film used here is Au, Ag or C.
r, etc., vacuum deposition, sputtering, plasma CV
It is formed by a dry film forming method such as D or a wet film forming method such as electroplating or electroless plating. The insulating film deposited on the flat electrode is an oxide film such as SiO ₂ , ZrO ₂ or Si ₃ N 2.
₄ , a nitride film of TiN or the like, which is formed by the above-mentioned dry or wet film deposition method like the metal film.

In the embodiment shown in FIG. 1, the insulating film is deposited only on the flat electrode, but the present invention is not limited to this. As shown in FIG. The insulating film may be deposited on the entire surface, or the same effect can be obtained by depositing the insulating film on both the planar electrode and the side surface electrode as shown in FIG. Since the area of the side surface electrode is much smaller than the area of the plane electrode, the above effect can be obtained if at least the insulating film is deposited on the plane electrode.

Further, the present invention is not limited to the shape of the flat electrode, and may have an electrode shape as shown in FIG. 4 which is different from the electrode shape shown in FIG. 1, for example.

When a crystal oscillator is incorporated in a crystal unit,
The crystal oscillator must be bonded to the plug and then covered with a case in vacuum. A metal paste such as solder or Ag is used for coupling the crystal oscillator piece and the plug, and a similar material is also used for coupling the plug and the case. In recent years, plugs and cases made of ceramics have been used for surface mounting, but adhesives such as solder and metal paste are also used for coupling with the crystal oscillator.
If the gas emitted from the plug, the case, or the adhesive is adsorbed on the electrode film of the crystal oscillation piece, the weight of the crystal oscillation piece increases, so that the oscillation frequency shifts or CI increases. Although the conventional electrode film is made of a metal film and gas is easily adsorbed, the present inventor has found that the gas adsorption amount of the insulating film is extremely lower than that of the metal film. Table 1 shows the comparison test results of the examples (Samples 1 to 3) of the present invention and the comparative examples (Samples 4 to 6). In the test, the amount of change in oscillation frequency (ΔTo) and the amount of change in CI (ΔCI) when left for 1000 hours at a temperature of 100 ° C. were investigated.

[Table 1] As is clear from Table 1, the crystal oscillator piece (Sample 1-3) according to the present invention shows almost no change in oscillation frequency and CI, and the accuracy is greatly improved even when compared with Comparative Examples (Samples 4 to 6). You can see that

Further, since the insulating film is deposited on the flat electrode, even if dust is attached between the flat electrode and the side electrode, the short circuit between the electrodes does not cause oscillation stop. In particular, it was extremely difficult to eliminate the dust generated from the above-mentioned plug and case adhesive and the dust generated during the manufacturing process, but it is easy to solve this problem by depositing an insulating film on the flat electrode. I was able to.

In this embodiment shown in Table 1, an oxide film was used as the insulating film. However, in addition to the oxide film, the insulating film such as the above-mentioned nitride film or fluoride film is similar to the result shown in Table 1. Good results were obtained.

The present invention is not limited to the outer shape of the crystal oscillating piece of this embodiment, but can be applied to crystal oscillating pieces of any shape. For example, FIG. 5 shows a cross-sectional view of the vibrating portion of the vertical vibrator, but the above-described result can be obtained by adopting the configuration of the present invention.

[0016]

As described above, according to the crystal oscillating piece of the present invention, since the insulating film is provided on at least the plane electrode among the plane electrode and the side surface electrode constituting the electrode, the plug forming the crystal resonator is formed. It is possible to prevent the gas emitted from the case, the case, and the adhesive from adsorbing onto the flat electrode of the crystal oscillation piece, and as a result, obtain a high-precision crystal resonator without characteristic deterioration such as a change in oscillation frequency or an increase in CI. be able to. Further, there is no short circuit due to adhesion of dust between the plane electrode and the side electrode, that is, oscillation stoppage is eliminated, and a highly reliable crystal oscillator can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a vibrating portion of a crystal oscillating piece of the present invention.

FIG. 2 is a cross-sectional view showing a vibrating portion of a crystal oscillator piece according to the present invention.

FIG. 3 is a cross-sectional view showing a vibrating portion of the crystal oscillator piece of the invention.

FIG. 4 is a cross-sectional view showing a vibrating portion of a crystal oscillator piece according to the present invention.

FIG. 5 is a cross-sectional view showing a vibrating portion of the crystal oscillator piece of the invention.

FIG. 6 is a cross-sectional view showing a vibrating portion of a conventional crystal oscillator piece.

FIG. 7 is a diagram showing a conventional crystal oscillator.

[Explanation of symbols]

11, 12, 13, 14, 15, 16, 17 Crystal oscillation piece 21, 22, 23, 24, 25, 26 Planar electrode 31, 32, 33, 34, 35, 36 Side electrode 41, 42, 43, 44, 45 Insulating film 57 Plug 67 Case 77 Crystal unit

Claims (1)

[Claims] 1. A crystal having a plane electrode made of a metal film provided on a plane of a crystal plate of a crystal oscillation piece made of one crystal plate and a side electrode made of a metal film provided in a thickness direction of the crystal plate. A crystal oscillator piece having an insulating film on at least the planar electrode.