JPH08298425A - Crystal vibrator - Google Patents

Abstract

PURPOSE: To keep a crystal impedance low stably by using a stimulation electrode film made of a low resistance metal and a protection layer provided thereon so as to prevent solder on a support electrode film from flowing out onto the stimulation electrode film. CONSTITUTION: A stimulation metallic film 5 formed on a upper and side faces of two vibration branches 3 extended in parallel from a base 2, a frequency adjustment metallic film 6 at the tip of the vibration branch and two support metallic films 4 at the base are provided to a tuning fork shaped crystal chip 1. In the manufacture of the vibrator, a metallic layer 8 is made on the crystal chip 1 at first by an active material with a small electric resistance. A 1st support metallic layer 10 is formed with an active metal to the support metallic film 4 and the frequency adjustment metallic film 6, and a 2nd support metallic layer 11 is made by a stable metal. Then the surface of the active metallic layer 8 is oxidized and nitrided by a heat treatment or the like to form a protective layer 9. Since no reaction is produced to the stable metallic films 4, 6, soldering is made possible and the solder does not flow to the stimulation electrode film 5 protected by the protection film 9.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an X-cut or AT
This is due to the structure of the metal film electrode of the cut crystal unit.

[0002]

2. Description of the Related Art The structure of a metal film electrode of a conventional crystal resonator will be described with reference to FIGS. FIG. 3 is a plan view showing electrodes of a crystal resonator in a conventional example.
FIG. 7 is a cross-sectional view showing a structure of a support portion of a crystal unit in a conventional example.

As shown in FIG. 3, an exciting metal film 5 provided on the plane and side surfaces of the crystal blank 1, a supporting metal film 4 provided on the base 2, an exciting metal film 5 and a supporting metal film 4. The metal film 7 for extraction provided between the two and the metal film 6 for frequency adjustment provided at the tip of the vibrating branch 3.

As shown in FIG. 4, the support portion structure of the crystal unit has the same metal film structure as that of the exciting metal film 5 and the supporting metal film 4, and the chrome which is an active material is formed on the crystal piece 1. Alternatively, it has a two-layer film structure of a first metal layer 8 made of nickel and a second metal layer 14 made of chemically stable material gold or palladium. On the other hand, the extraction metal film 7 is composed of a single layer of the first metal layer 8 made of chromium or nickel.

In the metal film 7 for extraction, active materials such as chromium and nickel are exposed. Therefore, the surface of the metal film for extraction 7 is oxidized, nitrided, or carbonized to form the protective layer 9, and the protective layer 9 is connected to the lead wire
It has a role of preventing the solder 13 for joining the second metal layer 14 from flowing into the exciting metal film 5.

[0006]

As described above, in the metal film structure shown in FIGS. 3 and 4, the diffusion of the solder 12 is caused by the protective layer 9 on the surface of the first metal layer 8 which is the metal film 7 for extraction. And the solder 12 stays on the supporting metal film 4 and prevents the solder 12 from flowing to the exciting metal film 5.

When the solder 12 flows on the exciting metal film 5,
Since the crystal impedance (CI) value, which is a basic characteristic of the crystal unit, deteriorates, it is excellent in preventing the deterioration of the CI value.

However, the metal film for extraction 7 is a single layer of the first metal layer 8 and has a small film thickness, so that the electrical resistance is large and the crystal impedance is deteriorated due to the variation in the film thickness.

Since the first metal layer 8 has a role of enhancing the adhesion between the crystal blank 1 and the second metal layer 14, it is made of the above-mentioned active material such as chromium or nickel. In addition, since these chromium and nickel materials have high mechanical stress after the film formation, if the film is thick, it hinders vibration and the crystal impedance, which is a basic characteristic of the crystal resonator, increases. Therefore, the film thickness of the first metal layer 8 must be suppressed to several to several tens of nm, resulting in an increase in electrical resistance.

Therefore, it is difficult for the conventional technique described with reference to FIGS. 3 and 4 to stabilize the crystal impedance, which is the basic characteristic of the crystal unit, at a low level.

An object of the present invention is to solve the above problems and prevent the flow of solder to the excitation electrode film at the time of connecting the lead wire of the external electrode and the supporting metal film on the crystal piece, and further the crystal oscillator. It is to provide a structure of a crystal resonator which is excellent in stability of crystal impedance which is a basic characteristic of

[0012]

In order to achieve the above object, the crystal resonator of the present invention adopts the structure described below.

The crystal unit according to the present invention comprises an exciting metal film comprising a first metal layer and a protective layer provided on the plane and side surfaces of the crystal piece, a first metal layer provided on the base of the crystal piece, and a first metal layer. It has a supporting metal film composed of a first supporting metal layer and a second supporting metal layer on the metal layer, and a frequency adjusting metal film provided in the vibrating branch portion.

[0014]

In the crystal unit of the present invention, the first supporting metal layer and the second metal layer on the first metal film on the base of the crystal piece and the surface of the first metal layer of the exciting metal film are formed. It has a protective layer composed of an oxide layer, a nitride layer, or a carbonized layer. As a result, the protective layer prevents the solder on the supporting electrode film from diffusing into the area other than the supporting electrode film.
Therefore, the solder is prevented from flowing to the exciting metal film.

Further, a protective layer is provided on the surface of the first metal layer of the exciting metal film. Therefore, the electrical resistance can be reduced, and the crystal impedance, which is the basic characteristic of the crystal unit, is low and stable. Also, by providing a protective layer,
Since the electrode film for excitation is chemically stable, the change of the electrode film with time is small and the frequency aging is stable.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A metal film electrode structure of a crystal unit according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing a tuning fork type crystal unit according to an embodiment of the present invention.
FIG. 2 is a sectional view showing a supporting portion of a tuning fork type crystal unit according to an embodiment of the present invention. Hereinafter, description will be made with reference to FIG. 1 and FIG. 2 alternately.

As shown in FIG. 1, a crystal unit includes a crystal piece 1 in the shape of a tuning fork, and an excitation metal film 5 provided on the planes and side surfaces of two vibrating branches 3 extending in parallel from a base 2. ,
A frequency adjusting metal film 6 provided at the tip of the vibrating branch portion 3;
It has two supporting metal films 4 provided on the base 2.

The mutual relationship of the metal films is such that the exciting metal film 5 and the supporting metal film 4 are connected to each other at the base 2 of the crystal blank 1 and the frequency adjusting metal film 6 and the exciting metal film 5 are separated from each other. .

Next, the structure of the supporting portion of the crystal unit will be described with reference to FIG. As shown in FIG. 2, the structure of the supporting portion of the tuning fork type crystal unit includes a first metal layer 8 made of aluminum, titanium or copper, which is an active material having a small electric resistance, on the crystal piece 1. Set up.

The supporting portion for joining the lead wires 13 with solder is chemically stable with the first supporting metal layer 10 made of chromium or nickel which is an active material on the first metal layer 8. It is composed of a two-layer film with the second supporting metal layer 11 made of a material such as gold or palladium. Then, a protective layer 9 is further provided on the surface of the exciting metal film 5. This protective layer 9 is used as the protective layer 9 by oxidizing, nitriding, or carbonizing the excitation metal film 5.

Next, a method for manufacturing the electrodes of the crystal resonator of the present invention shown in FIGS. 1 and 2 will be briefly described.

First, as shown in FIG. 2, a first metal layer 8 is formed on a crystal piece by forming a metal film to be an electrode for excitation by a sputtering method or a vacuum evaporation method.

Next, only the supporting portion for the lead wire 13 is first
The first supporting metal layer 10 and the second supporting metal layer 10 of the supporting electrode film 4 are formed on the second metal layer 8 by using a sputtering method or a vacuum deposition method.
The supporting metal layer 11 is formed. At the same time, the frequency adjusting metal film 6 of the vibrating branch portion 3 is formed under the same conditions.

Thereafter, heat treatment or plasma treatment is performed in an oxidizing atmosphere, a nitriding atmosphere, or a carbonizing atmosphere to utilize that the first metal layer 8 is an active material,
The surface of the excitation metal film 5 is oxidized, nitrided, or carbonized to form the protective layer 9. Here, since the supporting metal film 4 and the frequency adjusting metal film 6 have the chemically stable second supporting metal layer 11, oxidation, nitriding, or carbonization reaction does not occur.

Next, a method of connecting the lead wire 13 of the external electrode and the supporting metal film 4 as shown in FIG. 2 will be described.

As described above, the lead wire 13 as an external electrode is connected to the formed first metal layer 8 using the solder 12. As the joining member, the solder 12 is generally used because of its advantages such as stability of connection and low cost.

When the amount of coating is large, the connection by the solder 12 flows into the metal film 5 for excitation, which hinders the excitation of the crystal piece 1.
The crystal impedance, which is a basic characteristic of the crystal unit, may deteriorate.

In order to prevent the flow of the solder 12 described above,
A protective layer 9 is provided on the surface of the first metal layer 8. The protective layer 9 made of oxidation, nitridation, or carbonization prevents diffusion when solder is melted.

Further, the area of the protective layer 9 is the supporting metal film 4.
It is fixed in the range of. Therefore, the connection range of the solder 12 becomes constant, and the crystal impedance becomes uniform.

Further, if the adhesion between the first metal layer 8 and the crystal blank 1 is weak, the first metal layer 8 is soldered when the solder melts.
2 may be diffused more than necessary, the first metal layer 8 may be partially thin and the resistance may be increased, and the crystal impedance may be deteriorated.

For this reason, in the supporting portion metal film 4, the first supporting metal layer 10 made of an active material such as chromium or nickel is provided on the first metal layer 8 to enhance the adhesion between the films and the first supporting metal layer 10. This structure prevents the solder 12 from diffusing into the metal layer 8.

Further, by providing the second supporting metal layer 11, the connection with the solder 12 and the first supporting metal layer 10 are formed.
Keeps close contact with.

In the above description, the tuning fork type crystal unit is explained, but the present invention can be applied to all crystal units such as AT cut crystal unit and BT cut crystal unit.

[0034]

As described above, according to the present invention, the first supporting metal layer and the second supporting metal layer are provided on the first metal layer, and the first supporting metal film other than the supporting metal film is provided. By providing a protective layer on the surface of the metal layer, the solder prevents the protective layer from flowing in the direction of the exciting metal film when connecting with the lead wire, which is an external electrode, and the solder is within the range of the supporting metal film. Therefore, the crystal impedance, which is the basic characteristic of the crystal unit, can be stabilized and made uniform.

Further, by providing the protective layer on the surface of the first metal layer, the frequency change of the crystal unit over time becomes small.

[Brief description of drawings]

FIG. 1 is a plan view showing electrodes of a crystal resonator according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a structure of a support portion of a crystal unit according to an embodiment of the present invention.

FIG. 3 is a plan view showing electrodes of a crystal resonator in a conventional example.

FIG. 4 is a cross-sectional view showing a structure of a supporting portion of a crystal unit in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystal piece 4 Metal film for support 5 Metal film for excitation 6 Metal film for frequency adjustment 7 Metal film for extraction 8 First metal layer 9 Protective layer

Claims (3)

[Claims] 1. An excitation metal film comprising a first metal layer and a protective layer provided on the plane and side surfaces of a crystal piece, a first metal layer provided on the base of the crystal piece, and a first metal layer on the first metal layer. A supporting metal film comprising a first supporting metal layer and a second supporting metal layer;
A crystal resonator having a frequency adjusting metal film provided on a vibrating branch portion. 2. The crystal unit according to claim 1, wherein the crystal piece is X-cut or AT-cut. 3. The crystal unit according to claim 1, wherein the protective layer is an oxide layer, a nitride layer, or a carbonized layer.