JP3001856U - Crystal oscillator - Google Patents

Abstract

(57) [Summary] [Purpose] Stable resonance characteristics can be maintained for a long period of time by blocking the chemical reaction between the active gas such as oxygen remaining in the container and the metal forming the electrode. Provide a crystal unit. [Structure] A crystal resonator in which an electrode 2 is formed on a plate surface of a crystal plate 1 formed into a predetermined shape, and an oxide film 3 is deposited on the electrode, and an electrode in the crystal resonator. 2 is characterized in that it is formed by vapor deposition of silver or aluminum, and that the oxide film 3 is formed by sputtering in this crystal unit.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a crystal unit having stable vibration characteristics.

[0002]

[Prior art]

 Recently, piezoelectric vibrators have been used as a reference for frequency, time, etc. in various electronic devices. In particular, crystal oscillators that use quartz as a piezoelectric body have good electrical characteristics and high performance, but are inexpensive, and are used in many electronic devices. As a structure of such a crystal unit, for example, the crystal pieces are held by the tip portions of a pair of terminals implanted in the base. This crystal piece was formed by cutting artificial quartz crystal at a predetermined angle with respect to the crystal axis to form a strip shape, a round plate shape, etc., and forming electrodes by evaporating aluminum, silver, etc. on the front and back plate surfaces. It is a thing.

Then, the crystal piece is held by the terminals, and the electrodes formed on the plate surface are led out to the outside through the terminals. Then, the base is covered with a cylindrical metal cover having an opening on the lower surface, the opening edge is soldered to the outer peripheral edge of the base, and resistance welding is performed to hermetically seal the base.

However, in such a crystal oscillator, in order to maintain a stable state inside the container sealed by the base and the cover, for example, an inert gas may be filled in the container or a vacuum state may be set. It is being appreciated. However, since it is difficult to completely replace the gas in the container with an inert gas, it is inevitable that some impurities will be mixed in. Even if the gas can be completely replaced with an inert gas, the inert gas itself It is unavoidable that impurities contain trace amounts of impurities such as active oxygen.

Such oxygen reacts with aluminum, silver, etc., which composes the electrode formed on the plate surface of the crystal piece, and is chemically altered to change the resonance characteristics such as the resonance frequency of the crystal unit. There is a problem that impairs long-term stability. Particularly in recent high-stability, high-precision quartz oscillators, even if the resonance characteristics change due to the deterioration of the electrodes due to the action of a slight amount of oxygen remaining in the container, it becomes a serious problem.

[0006]

[Problems to be solved by the device]

 The present invention has been made in view of the above circumstances and provides stable resonance characteristics for a long period of time by preventing a chemical reaction between an active gas such as oxygen remaining in the container and a metal forming the electrode. The object is to provide a crystal unit that can be maintained.

[0007]

[Means for Solving the Problems]

 According to the present invention, a crystal resonator characterized in that an electrode is formed on a plate surface of a crystal plate molded into a predetermined shape, and an oxide film is deposited on the electrode, and the electrode in this crystal resonator is It is characterized in that silver or aluminum is vapor-deposited or formed by sputtering, and that in this crystal unit, the oxide film is formed by sputtering.

[0008]

【Example】

 An embodiment of the present invention will be described in detail below with reference to the sectional view of the crystal piece shown in FIG. 1 and the plan view of the crystal piece shown in FIG. In the figure, 1 is a crystal plate. This crystal plate 1 is formed by cutting artificial quartz crystal at a predetermined angle with respect to the crystal axis to form a plate shape, and further forming the external shape into a strip shape, a round plate shape, or the like, with both side plate surfaces being desired. It is ground to a thickness corresponding to the resonance frequency of. Then, the electrodes 2 are formed on both sides of the crystal plate 1 by, for example, vacuum vapor deposition. When the electrodes 2 are formed on the crystal plate 1 having a round plate shape, for example, the electrodes 2 are formed so as to face the central portions of both side plate surfaces, and the electrodes 2 are led out in opposite directions to the edges. I am trying.

When the electrode 2 is formed by vacuum vapor deposition, metal such as aluminum or silver is heated in a vacuum atmosphere to generate metal vapor. Then, the quartz plate 1 having a mask of a predetermined shape arranged on the front surface is exposed to metal vapor, and the metal is vapor-deposited on the plate surface to form the electrode 2. Then, an oxide film 3 is formed on the electrode 2 so as to cover it. Since the oxide forming the oxide film 3 generally has a high melting point, it is difficult to obtain the vapor of the oxide by means of resistance heating utilizing electric resistance, for example, by the same means as the electrode 2. Many. In such a case, the oxide film 3 can be easily formed by depositing an oxide so as to cover the electrode 2 by sputtering, for example.

As is well known in the art, the crystal piece having the oxide film 3 formed on the electrode 2 is sandwiched by, for example, the tips of a pair of terminals planted in the base and coated with a conductive adhesive or the like. The electrode and the terminal are electrically connected. Then, a small amount of metal is vapor-deposited on the electrode to adjust the resonance frequency accurately, and then the base is covered with a cover and hermetically sealed to complete the crystal unit.

With such a configuration, the surface of the electrode 2 is covered with the oxide film 3, so that the electrode 2 does not come into direct contact with the atmosphere gas. However, even if a gas having a strong activity such as oxygen remains in the sealed container, it does not react with the electrode 2, and the oxide film 3 is chemically stable and does not particularly react with oxygen. It can maintain a chemically stable state. Furthermore, since the surface of the electrode 2 is covered with the oxide film 3, the mechanically stable state can be maintained. Therefore, the crystal resonator using the above crystal piece can maintain stable resonance characteristics for a long period of time and can obtain good long-term stability.

[0012]

[Effect of device]

 As described in detail above, according to the present invention, the electrodes formed on the quartz plate can be maintained in a chemically and physically stable state, and thereby stable and good resonance characteristics can be obtained for a long period of time. It is possible to provide a crystal unit that can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of a quartz piece according to an embodiment of the present invention.

FIG. 2 is a plan view of the crystal piece of the embodiment shown in FIG.

[Explanation of symbols]

 1 Crystal plate 2 Electrode 3 Oxide film

Claims (3)

[Scope of utility model registration request] 1. A crystal resonator comprising: a crystal plate formed into a predetermined shape; an electrode formed on a plate surface of the crystal plate; and an oxide film deposited on the electrode. . 2. The crystal resonator according to claim 1, wherein the electrodes are formed by vapor-depositing silver or aluminum. 3. The crystal resonator according to claim 1, wherein the oxide film is formed by sputtering.