JP2000031773A - Crystal vibrator of surface mount type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent vibrating characteristics, to improve the yield in the assembling process and to reduce the cost by preventing a conductive adhesive from being flower toward a center of a crystal chip face in a process of adhering a crystal chip. SOLUTION: A crystal chip 14 whose plate middle part is formed with an exciting electrode 15 is supported by a support electrode 13 placed on an inner face in continuity with a mount electrode placed to an outer face of a ceramic- made base 11 by using a conductive adhesive and the exciting electrode is led out toward the mount electrode. A projected dam 16 to prevent spread of the conductive adhesive toward the center of the crystal chip is formed to an edge of the crystal chip toward the center of the chip.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-mount type crystal unit having a small shape and capable of obtaining good vibration characteristics.

[0002]

2. Description of the Related Art In recent years, various kinds of electronic devices often use a quartz oscillator as a reference for frequency and time. On the other hand, miniaturization and weight reduction of electronic equipment and automation of the assembly process are desired,
Surface mount components tend to be used extensively. For this reason, a crystal resonator of a surface mount type is also desired.

In such a surface-mount type crystal unit,
For example, as shown in the perspective view of FIG. 2, a holding electrode 2 is formed on an inner plate surface of a ceramic base 1, one end of a strip-shaped quartz piece 3 is placed thereon, and fixed using a conductive adhesive. At the same time, electrical conduction with the excitation electrode 4 formed at the center of the plate surface of the crystal blank 3 is achieved.

An annular seal ring 5 is fixed to the periphery of the base 1, and the upper surface of the seal ring 5 is hermetically sealed with a lid (not shown). Also, on the outer plate surface of the base 1,
The mounting electrode is formed by being electrically connected to the holding electrode 2, and the mounting electrode is soldered and mounted on a printed circuit board.

However, in the case of such a structure, if the conductive adhesive between the holding electrode and the lead-out end of the electrode of the crystal blank spreads toward the center of the plate surface of the crystal blank, the vibration characteristics are significantly impaired. . Therefore, the work of mounting and fixing the crystal blank on the holding electrode requires careful attention, and there has been a problem that the cost increases due to an increase in the number of steps and a decrease in the yield.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and prevents the conductive adhesive from flowing toward the center of the plate surface of the crystal piece in the step of holding the crystal piece. It is an object of the present invention to provide a surface-mount type crystal unit which can obtain excellent vibration characteristics and can improve the yield of the assembling process and reduce the cost.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a quartz crystal in which a mounting electrode provided on an outer plate surface of a ceramic base is electrically connected to a holding electrode provided on an inner plate surface and an excitation electrode is formed in the center of the plate surface. While holding the piece using a conductive adhesive and leading the excitation electrode to the mounting electrode, the holding electrode is located at the edge of the crystal piece in the direction of the plate surface center in the direction of the plate surface center of the crystal piece. The present invention is characterized in that a ridge for preventing spread of the conductive adhesive is formed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to an assembled perspective view of main parts shown in FIG. In the figure, reference numeral 11 denotes a substantially rectangular base made of a plate-like ceramic, and a metal seal ring 12
Is provided. The base 11 and the seal ring 12 form a box-shaped container as shown in FIG.

A mounting electrode (not shown) is formed on the outer bottom surface of the base 11, and the mounting electrode is soldered to a conductive pattern of a printed wiring board for mounting. The holding electrode 13 is formed on the inner plate surface of the base 11 so as to be electrically connected to the mounting electrode. This mounting electrode and holding electrode 1
Numeral 3 is obtained by plating nickel, gold or the like on a thick metal film formed by, for example, a metallizing process.

[0010] Then, a conductive adhesive is applied to the holding electrode 13, and the crystal blank 14 is placed and fixed. This crystal piece 14
Is, for example, an AT-cut crystal blank that excites thickness-shear vibration. Such a crystal blank 14 is formed by cutting an artificial quartz crystal at a predetermined angle with respect to the crystal axis, forming a plate shape, and polishing the crystal to a thickness corresponding to a desired resonance frequency. The external shape is formed into, for example, a strip shape, and the excitation electrode 15 is formed facing the front and back plate surfaces.

In the case where one end of the crystal blank 14 is held, the excitation electrodes 15 extend to one end of the crystal blank 14 in the longitudinal direction. Then, the holding electrode 13
Are, for example, substantially square and are provided on both sides of a center line along the longitudinal direction inside the base 11 and at predetermined intervals at longitudinal ends. The inner corner 13a of the holding electrode 13 on the center side of the base 11 is formed in an arc shape.

On the upper surface of the holding electrode 13, an inner corner 13a on the center side of the base 11 and the corner 1a
A convex bank 16 made of a metal thick film having a thickness of about 20 to 100 microns is formed along the side sandwiching 3a.
The convex ridge 16 may be formed by, for example, performing a metallizing process on the holding electrode 13.

The upper surface of the holding electrode 13 is provided with
6, for example, at the above-mentioned arc-shaped corner portion 13a
A convex portion 17 having the same height as the convex bank 16 may be provided in a bar shape toward. This convex portion 17 may be formed by metallization similarly to the above-mentioned convex bank 16.

Then, a conductive adhesive is applied to the holding electrode 13, and the lead-out end of the excitation electrode 15 of the crystal blank 14 is placed and fixed thereon, and the crystal blank is held. Are electrically conducted.
The upper surface of the seal ring is hermetically sealed with a lid (not shown).

In this way, when the conductive adhesive is applied to the holding electrode 13 and the lead-out end of the excitation electrode 15 of the crystal blank 14 is placed and fixed thereon, the conductive adhesive is Of the crystal blank 14 in the center direction can be prevented. Therefore, the crystal blank 14 is connected to the holding electrode 1.
The work of mounting and fixing to 3 can be easily performed, and good vibration characteristics can be obtained.

Therefore, the yield in the step of fixing the crystal blank to the holding electrode can be increased, and the variation in characteristics can be extremely reduced. In addition, when the convex portion 17 is provided, the crystal blank 1
The crystal blank 14 can be easily held parallel to the plate surface of the base 11 when the end of the base 4 is placed on the holding electrode 13.

Furthermore, since the upper surface of the holding electrode 13 is formed with complicated irregularities, there is an advantage that the adhesive force of the conductive adhesive can be increased. If the edge of the holding electrode 13 in the center direction of the plate surface of the base 11 is formed into an arc shape as shown in FIG. can do.

According to the above-described embodiment, the end of the crystal blank 14 is held at a position higher than the upper plate surface of the base 11 by the thickness of the ridge of the holding electrode 13. Therefore, even when the plate surface of the crystal blank 14 is formed into a convex lens shape, for example, when beveling is performed, there is an effect that the center of the plate surface of the crystal blank 14 can be prevented from contacting the base 11.

[0019]

As described in detail above, according to the present invention,
The conductive adhesive used for holding the crystal blank and leading the excitation electrode can be prevented from flowing out toward the center of the plate surface of the crystal blank, whereby uniform and good vibration characteristics can be obtained. It is possible to provide a surface-mount type crystal unit that can improve the yield and reduce the price of a product.

[Brief description of the drawings]

FIG. 1 is an assembled perspective view of a main part of an embodiment of the present invention.

FIG. 2 is a perspective view showing the inside of a conventional surface mount type crystal unit.

[Explanation of symbols]

 11 base 13 holding electrode 14 crystal blank 16 ridge 17 ridge

Claims (6)

[Claims] 1. A quartz chip having an excitation electrode formed at the center of the plate surface on a holding electrode provided on the inner plate surface and electrically connected to a mounting electrode provided on an outer plate surface of a ceramic base, using a conductive adhesive. Wherein the excitation electrode is led out to the mounting electrode, wherein the holding electrode has a projection on an edge of the base in the center of the plate surface to prevent the conductive adhesive from spreading in the center of the crystal blank in the plate surface. A surface-mount type crystal unit characterized by forming a bank. 2. The surface-mounted crystal resonator according to claim 1, wherein the edge of the holding electrode in the center direction of the plate surface of the base has an arc shape. 3. A surface-mounted crystal resonator according to claim 1, wherein the crystal piece is a strip. 4. A holding electrode according to claim 1, wherein the holding electrode is formed with a convex portion having the same height at a position away from the convex bank to hold the crystal blank parallel to the base plate surface. Surface mount type crystal unit. 5. A surface-mount type crystal resonator according to claim 1, wherein the crystal piece holds one end in a longitudinal direction of a strip shape. 6. A surface-mount type crystal unit according to claim 1, wherein the crystal piece holds both ends of the strip in the longitudinal direction.