JPH06112758A - Crystal vibrator - Google Patents

Abstract

PURPOSE:To prevent an inconvenient case where Ag of an electrode layer evaporates and reacts to the gas of a conductive adhesive when the upper and lower bodies of a container are sealed and the frequency varies much before and after the sealing process. CONSTITUTION:A crystal vibrator piece 4 contains at least a pair of electrodes and a lead part formed on the surface of a crystal piece 5. Then the piece 4 is stored in a container 3 and at the same time the container is sealed at a high temperature. Then the lead part is connected to an external terminal of the container 3. In such a constitution of a crystal vibrator, the electrodes and the lead part are covered with a foundation metal skin layer 12, a silver or gold electrode layer 16 formed on the layer 12, and a nickel cover layer 17 formed on the layer 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal unit in which a crystal unit is housed in a container and the container is sealed.

[0002]

2. Description of the Related Art A crystal resonator to be soldered on the surface of a printed circuit board or the like is required to have a low mounting height on the printed circuit board.

For this reason, the crystal unit shown in FIG. 3 is used.

As shown in the figure, a crystal oscillator piece 4 is housed in a container 3 composed of an upper body 1 and a lower body 2 and made of alumina-based ceramics, glass, crystal or the like.
The crystal unit 4 is a disk-shaped crystal unit 5 as shown in FIG.
The electrodes 6a and 6b are attached to both main surfaces of the
Leads 7a and 7b are attached from 6b in opposite directions. As the crystal oscillator piece 4, there is also a crystal piece 5 having a substantially rectangular shape as shown in FIGS. 5 (a) and 5 (b). Both ends of the crystal oscillator piece 4 are supported by lead frames 8a and 8b serving as holders, and the lead frames 8a and 8b are sandwiched between the upper body 1 and the lower body 2 and supported in the container 3. The upper body 1 and the lower body 2 are abutted against each other with the crystal resonator piece 4 housed in the container 3 via the sealing material 9, and heat of 400 ° C. or more is applied for several minutes to be sealed to each other. As the sealing material 9, low temperature glass is used. The lead 7a and the lead frame 8a are made of a conductive adhesive 10a.
The lead 7b and the lead frame 8b are connected via a conductive adhesive 10b. The ends of the lead frames 8a and 8b are guided to the lower surface of the container 3 to form the external terminals 11a and 11b. In addition, the lead part 7
In some cases, a and 7b are led out in the same direction instead of the opposite direction.

FIG. 6 shows an enlarged view of a portion A in FIGS. 3 and 5 (b). In the figure, 13 is a base plating layer made of nickel (Ni), which has good bonding properties with the crystal piece 5, and 14 is an electrode layer made of silver (Ag). The lead portion 7a has the same structure.

As a method of forming these electrodes and the like,
For example, in a vacuum container, first, Ni is heated and vapor-deposited on a predetermined surface of a crystal piece to form a base plating layer, and then only Ag is heated and vapor-deposited to form an electrode layer having a predetermined thickness. Method is used.

[0007]

However, since the temperature of 400 ° C. or more is applied for several minutes or more in the process of sealing the upper body and the lower body as described above, the crystal oscillator piece in the container is in this process. The temperature of the electrodes and leads of the electrode rises to the same level as the temperature of the sealing part, and the gas contained in the conductive adhesive and low melting point glass is released and reacts with the exposed silver on the electrode surface before and after sealing. The frequency changes greatly. In addition, the vaporization of Ag causes the electrode layer to be consumed, the electrode layer becomes thin, and non-transmission occurs due to improper conduction of electricity. There is a problem that the oscillation frequency of the child piece fluctuates greatly (becomes higher) and ends up.

On the other hand, in consideration of vaporization and consumption of the electrode layer, it is possible to vapor-deposit and form Ag thicker by that amount,
A from the electrode layer when sealing the upper body and the lower body with a sealing material
Since it is difficult to keep the vaporization consumption of g constant,
There is a large variation difference in the oscillation frequency of each crystal unit after sealing, which exceeds the adjustable range, or there is a problem in stably producing a crystal unit with good oscillation frequency accuracy.

On the other hand, as shown in Japanese Utility Model Laid-Open No. 2-41510, Cr is used for the base plating layer and Ag is used for the electrode layer.
Alternatively, Au may be used and Ni may be used as the coating layer,
At least three types of metal films must be formed, and the equipment for forming the films becomes complicated.

Therefore, an object of the present invention is to provide a crystal resonator that solves the above problems.

[0011]

[Means for Solving the Problems] The structure of the present invention for attaining such an object is to store a crystal resonator piece, in which at least a pair of electrodes and lead portions are provided on the surface of the crystal piece, in a container. In a crystal unit in which a container is sealed at a high temperature with a lead portion and an external terminal provided outside the container are connected via a conductive adhesive, an electrode and a lead portion are provided with a base plating layer made of nickel, It is characterized in that it is formed by covering with an electrode layer made of silver or gold provided on the base plating layer and a coating layer made of nickel provided on the electrode layer.

[0012]

Since the coating layer covering the electrode layer is provided, the gas of the conductive adhesive does not directly react with silver or gold,
Little change in frequency before and after sealing. In addition, since the electrode layer does not evaporate, the electrode layer does not become thin so that non-transmission due to improper energization does not occur.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. Since the present embodiment is an improvement of a part of the conventional crystal resonator, the same parts as those of the conventional one are designated by the same reference numerals, and the description thereof will be omitted.

An embodiment of the crystal unit according to the present invention is shown in FIG.
A description will be given based on (a) and (b). FIG. 1 corresponds to FIG.

As shown in the figure, the base plating layer 12 made of nickel similar to the conventional one is provided at a predetermined position on the main surface of the crystal blank 5.
Is thinly formed, and the electrode layer 16 made of silver is formed thereon with a predetermined thickness. Then, the coating layer 17 made of nickel is further thinly formed on the electrode layer 16, and the electrode layer 16 is covered with the coating layer 17. In this embodiment, the thickness of the base plating layer 12 is 50 to 500Å, and the electrode layer 16 is
Has a thickness of 500 to 3000Å, and the coating layer 17 has a thickness of 10 to 300Å.

As shown in FIG. 1 (b), in the portion of the lead portion where the electrode layer 16 and the lead frame 8a are connected,
The electrode layer 16 is exposed and connection is possible.

Next, the operation of such a crystal oscillator will be described. Since the electrode layer 16 is covered with the coating layer 17 and the coating layer 17 is made of Ni that forms an oxide film, vaporization of Ag in the electrode layer 16 during the sealing process is prevented. Therefore, the gas generated from the conductive adhesive does not react with Ag. Therefore, the change in frequency generated by the crystal unit before and after sealing is smaller than before. When the change in frequency before and after the sealing between the conventional crystal unit and the crystal unit according to the present invention was examined, the frequency change of a conventional Ni base plate and Ag electrode layer was averaged. Is ± 100 ppm or more, and further N
The change in frequency of the crystal resonator of the present invention provided with the coating layer made of i was ± 10 ppm or less on average.

Further, since the Ag does not evaporate in this way, the crystal oscillator does not become untransmitted as in the conventional case. Ag evaporates and the electrode 6a and the lead portion 7a
Fig. 2 (b) shows a conventional crystal oscillator piece 4 in which a part of
2A shows the crystal resonator piece 4 according to the present invention in which the coating layer 17 is formed on the electrode layer 16 and the electrode layer 16 does not evaporate.

In this embodiment, Ag is used as the electrode layer, but Au may be used instead. In addition, even if a mixed layer made of nickel (Ni) and silver (Ag) or gold (Au) is provided between the base plating layer and the electrode layer or between the electrode layer and the coating layer, the same result as above is obtained. Obtainable.

[0020]

As can be seen from the above description, according to the crystal resonator of the present invention, since the coating layer covering the electrode layer is provided, Ag or Au as the electrode layer seals the upper body and the lower body. At this time, it does not react with the vaporized conductive adhesive gas, and therefore the change in the frequency of the crystal resonator before and after sealing can be reduced.

Further, since the electrode layer does not evaporate, the crystal oscillator does not stop transmitting.

Furthermore, since both the base plating layer and the coating layer are made of Ni, the equipment can be prevented from becoming complicated even with a three-layer structure, and the production efficiency is high. Moreover, the conventional equipment for forming two types of metal layers can be used as it is.

[Brief description of drawings]

1A and 1B relate to a crystal unit according to the present invention, FIG. 1A is a partial sectional view of a crystal unit, and FIG. 1B is a sectional view showing a connecting portion between a lead portion and a lead frame.

2A and 2B relate to a crystal unit according to the present invention, FIG. 2A is an operation explanatory diagram of the crystal unit according to the present invention, and FIG. 2B is an operation explanatory diagram of a conventional crystal unit.

FIG. 3 is a configuration diagram of a conventional crystal unit.

FIG. 4 is a plan view of a conventional crystal resonator element.

5A and 5B relate to a conventional crystal unit, FIG. 5A is a plan view, and FIG. 5B is a front view.

FIG. 6 relates to a conventional crystal unit, and is shown in FIGS.
The expanded sectional view of the A section in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Upper body 2 ... Lower body 3 ... Container 4 ... Crystal oscillator piece 5 ... Crystal piece 6a, 6b ... Electrode 7a, 7b ... Lead part 10a, 10b ... Conductive adhesive 11a, 11b ... External terminal 12 ... Base plating layer 16 ... Electrode layer 17 ... Coating layer

Claims (1)

[Claims] 1. A crystal resonator piece having at least a pair of electrodes and a lead portion provided on the surface of a crystal piece is housed in a container and the container is sealed at a high temperature, and the lead portion and the outside are provided outside the container. In a crystal unit in which a terminal is connected via a conductive adhesive, an electrode and a lead portion are provided with a base plating layer made of nickel, and an electrode layer made of silver or gold and provided on the base plating layer. A crystal unit provided on the electrode layer and covered with a coating layer made of nickel.