JP2001102894A - Crystal vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal vibrator for preventing a ceramic container from being cracked or vibration characteristics from being lowered at the time of seam welding. SOLUTION: Concerning the crystal vibrator constituted by housing a crystal piece in the recessed main body of a container and welding a metal cover, the said metal cover is provided with a buffer band for preventing stretching caused by heat at the time of welding. Besides, welding is seam welding. Further, the buffer band is circulated around the outer periphery of the metal cover and made into groove on one main side and into projecting groove to be a projection on the other main side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal resonator for surface mounting in the technical technical field, and more particularly to a crystal resonator sealed by seam welding.

[0002]

2. Description of the Related Art A quartz resonator is widely used as a frequency and time reference source in various electronic devices because of its excellent resonance characteristics. In recent years, the surface mount type has become the mainstream under the lightness, shortness and small size, and one of these is a highly reliable seam welding sealing means.

(Example of Prior Art) FIG. 4 is a cross-sectional view of a quartz oscillator for explaining a conventional example. The crystal unit accommodates a crystal blank 2 in a concave ceramic container 1 and seals an opening surface of the metal cover 3 by seam welding. The ceramic container 1 has a two-layer structure of a bottom wall 1a and a frame wall 1b, and a metal ring 4 for welding is provided on an opening surface by an alloy solder of silver and copper. The metal cover 3 and the metal ring 4 are made of Kovar, and have nickel and gold plating on their joint surfaces (not shown). In seam welding, current is supplied by rotating rollers on both sides of the metal cover 3 to generate Joule heat in the abutting portion, particularly melting nickel plating, and joining by so-called resistance welding. Reference numeral 5 in the drawing is a conductive adhesive.

[0004]

[Problems to be Solved by the Invention]
However, the crystal resonator having the above configuration has the following problem due to heat generated during seam welding. That is,
The metal cover 3 expands due to the heat generated by seam welding, and contracts as the temperature decreases after welding. And
The metal cover 3 and the ceramic container 1 have different expansion coefficients. Therefore, stress is generated in the ceramic container 1 when the metal cover 3 expands and contracts during seam welding, and particularly, the bottom wall 1
There was a problem that the boundary (arrow P) of the frame wall 1b was chipped or cracked. In addition, there is a possibility that the bottom wall is bent by the stress to give a distortion to the crystal blank 2 to deteriorate the vibration characteristics. In particular, the effect is greater as the size is promoted and the thickness is reduced.

(Object of the Invention) It is an object of the present invention to provide a crystal resonator in which chipping of a ceramic container during seam welding and deterioration of vibration characteristics are prevented.

[0006]

The basic solution of the present invention is to provide a buffer band 6 on the metal cover 3 for preventing expansion and contraction due to heat during seam welding.

[0007]

According to the present invention, the buffer band 6 is provided on the metal cover 3 so that expansion and contraction due to heat during welding can be absorbed and the ceramic container 1 can be used.
To reduce the impact on Hereinafter, an embodiment of the present invention will be described.

[0008]

1 and 2 are views for explaining an embodiment of the present invention. FIG. 1 is a cross-sectional view of a quartz oscillator, and FIG. 2 is a plan view of a metal cover. The same parts as those in the prior art are denoted by the same reference numerals, and description thereof will be simplified or omitted. The crystal unit accommodates a crystal blank 2 in a ceramic container 1 having a concave shape as described above, and seals an opening surface of the metal cover 3 by seam welding. The metal cover 3 has a buffer band 6 for preventing expansion and contraction due to heat during seam welding. In this example, the buffer band 6 goes around the outer periphery of the metal cover 3, and has a groove on the outer surface and a projection groove on the inner surface. However,
The protrusion groove is located inside the ceramic container 1 and is formed by, for example, press working.

With such a configuration, expansion and contraction of the metal cover 3 during seam welding are absorbed by expansion and contraction of the projection groove. Therefore, the stress generated in the container body is reduced, and chipping or cracking is particularly prevented at the boundary between the bottom surface and the side surface. Also, the vibration characteristics are maintained satisfactorily by preventing bending of the bottom surface. The metal ring 4 also expands and contracts in the frame direction at the time of seam welding, but is hollow, so that the influence of expansion and contraction by the metal cover 3 is large.

Note that the buffer band 6 in this example is a metal cover 3
Of the ceramic container 1 during seam welding
And sealing leakage due to misalignment can be prevented.

In the above embodiment, the buffer band 6 has a groove on the outer surface and a protrusion on the inner surface. However, a protrusion groove on the outer surface and a groove on the inner surface may be used. Any projection groove having a surface as a projection may be used (not shown). In addition, although the projection groove circumscribes the outer periphery, for example, it may be provided only on four sides of the outer periphery (not shown), or may be formed in a cross shape at the center as shown in FIG. Further, it may be provided only in an oblique direction or one direction.

Although the buffer band 6 is formed as a projection groove, the effect can be expected even if the thickness is reduced by, for example, etching. In short, the buffer band 6 that absorbs expansion and contraction may be formed. In addition, although the seam welding is used for welding, for example, when welding is performed by irradiating an electron beam, heat is similarly generated, so that the present invention can be applied.

In the above-described embodiment, the crystal resonator in which only the crystal piece 2 is accommodated in the ceramic container 1 has been exemplified. However, the present invention can also be applied to a crystal oscillator in which an IC chip is accommodated. Is not excluded from the technical scope.

[0014]

According to the present invention, since the buffer band 6 for preventing expansion and contraction due to heat at the time of seam welding is provided on the metal cover 3, a crystal resonator in which chipping and cracking of the ceramic container 1 and deterioration of vibration characteristics are prevented is prevented. Can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a crystal unit illustrating one embodiment of the present invention.

FIG. 2 is a plan view of a metal cover illustrating one embodiment of the present invention.

FIG. 3 is a plan view of a metal cover for explaining another embodiment of the present invention.

FIG. 4 is a cross-sectional view of a crystal unit illustrating a conventional example.

[Explanation of symbols]

1 ceramic container, 2 crystal pieces, 3 metal cover, 4
Metal ring, 5 conductive adhesive, 6 buffer band.

Claims (3)

[Claims] 1. A crystal resonator in which a quartz piece is housed in a concave container body and a metal cover is welded, wherein a buffer band for preventing expansion and contraction due to heat during welding is provided on the metal cover. Crystal oscillator. 2. The crystal unit according to claim 1, wherein said welding is seam welding. 3. The crystal unit according to claim 1, wherein said buffer band is a projection groove which goes around the outer periphery of the metal cover and has a groove on one main surface and a protrusion on another main surface.