JP2023025498A - Crystal oscillator - Google Patents

Abstract

To provide a crystal oscillator that is sealed by a cold weld method, and provide a crystal oscillator using a bass that has the potential to reduce stress caused by the seal.SOLUTION: A crystal oscillator 10 includes a base 11 and a cover 53a sealed by a cold weld method, and a crystal oscillation piece 55 implemented in these bass and cover. Then, on the side wall of the base 11, a stress easing structure 11A is used. The stress easing structure may have an uneven structure formed on the side wall. The uneven structure has a continuous unevenness along the height direction (y direction), and the convex and concave are extended to the direction of the base height and orthogonal (X direction).SELECTED DRAWING: Figure 1

Description

The present invention relates to a crystal resonator sealed by the cold weld method.

In the application field of crystal oscillators, surface-mounted crystal oscillators using a ceramic base have become mainstream. However, in the case of high-stability crystal oscillators that require frequency stability on the order of ppb, crystal oscillators that are sealed using the cold-weld method are still often used for reasons such as hermetic reliability. .
FIG. 5 is a diagram for explaining a crystal oscillator 50 sealed and manufactured by the cold weld method. In particular, FIG. 5(A) is a front view showing a part of the crystal resonator 50 cut away, FIG. 5(B) is a side view showing a part thereof cut off, and FIG. 1 is a top view shown in FIG.
The crystal oscillator 50 is composed of a base 51 , a cover 53 , a crystal vibrating piece 55 and a conductive adhesive 57 .

The base 51 comprises a metal header 51a, a Kovar glass 51b filled in the metal header 51a, a lead 51c passing through the Kovar glass 51b, and a supporter 51d connected to the tip of the lead 51c. Typically, the metal header 51a is made of copper clad kovar and the cover 53 is made of oxygen-free copper or copper material. The crystal vibrating piece 55 is composed of an AT-cut crystal piece, an SC-cut crystal piece, or the like, and has an excitation electrode 55a and an extraction electrode 55b on the front and back.
The crystal vibrating piece 55 is fixed by a conductive adhesive 57 to the supporter 51d of the base 51 at the position of the extraction electrode 55b.
The base 51 and the cover 53 are joined together by pressing the flanges 51e and 53a of each other with a strong pressure to join them metal-to-metal.

JP 2009-55559 A Japanese Unexamined Patent Application Publication No. 2016-1788

In the case of a crystal oscillator for high stability, even if the residual stress generated at the time of sealing is slight, it adversely affects the crystal resonator element 55 over time. Therefore, for example, Patent Document 1 discloses a structure in which a through hole is formed in the edge region of the crystal vibrating piece 55 itself to prevent the stress from reaching the vibrating portion of the crystal vibrating piece 55 (the portion of the excitation electrode 55a). Proposed. Further, Patent Document 2 proposes a structure in which the shape of the supporter 51d is such that the stress is less likely to be transmitted. In this way, various measures have been conventionally taken to reduce the effects of residual stress.

However, in order to further improve the long-term stability of a highly stable crystal unit, we investigated the possibility of reducing the stress during sealing by the cold weld method, even for elements that have not been paid much attention so far. It is necessary to accumulate measures.
The inventor of this application focused on the header of the base used for sealing by the cold weld method and examined the possibility of reducing the stress.
This application has been made in view of the above points, and an object of the present invention is therefore to provide a crystal oscillator sealed by the cold weld method, which has the potential to reduce the stress caused by the sealing. The object of the present invention is to provide a crystal resonator using a base that has a thickness of 1.5 mm.

To achieve this goal, the inventors of this application have considered bases and covers that are sealed by the cold well method. That is, in the cold weld method, the base and the cover are fitted so as to cover the base with a predetermined gap G (see FIG. 5A) between the outer wall of the header of the base and the inner wall of the cover. are combined. Then, the flanges provided at the edges of the cover and the base (parts indicated by 51e and 53a in FIG. 5(A)) are pressurized for metal-to-metal joining. Therefore, it was thought that there is room for forming a stress relaxation structure using the gap G between the outer wall of the header of the base and the cover.
Therefore, according to the crystal resonator of the present invention, in the crystal resonator comprising a base and a cover sealed by a cold weld method, and a crystal resonator element mounted in the base and the cover, the base is provided with a stress relief structure on the side wall of the

In carrying out the present invention, it is preferable that the stress relieving structure is an uneven structure formed on the side wall.
Further, the uneven structure is a structure in which the unevenness is continuous along the height direction of the base, and each of the protrusions and the recesses extends in a direction perpendicular to the height direction of the base (hereinafter referred to as the first embodiment). (sometimes abbreviated as morphological structure) is preferable. With this structure, the unevenness of the stress relaxation structure is aligned along the direction in which the stress generated at the joint between the flange of the base and the flange of the cover extends to the crystal resonator element, so it is believed that the stress relaxation effect is likely to occur. .
However, even if the uneven structure has continuous unevenness along the direction perpendicular to the height direction of the base, and each of the unevenness and the unevenness extends in the height direction of the base, the stress is reduced. We believe that there will be a mitigating effect to some extent. That is, it is a concave image in which the arrangement of unevenness is orthogonal to the structure of the first embodiment. However, we believe that the structure of the first embodiment is preferable.
Further, it is considered that the uneven structure may be a circular, elliptical, or polygonal uneven structure randomly provided on the side wall.

Since the crystal oscillator of the present invention has the stress relaxation structure on the side wall of the base, it is considered that the stress generated at the joint between the flange of the base and the flange of the cover can be reduced as compared with the case without such a structure. Moreover, since the stress relief structure is provided at the predetermined gap G between the outer wall of the header of the base and the inner wall of the cover, it does not interfere with sealing. Therefore, it is possible to provide a novel structure that has the potential to alleviate the influence of the stress generated by cold-weld sealing on the crystal vibrating piece.

(A) to (C) are explanatory diagrams of the crystal resonator 10 of the first embodiment. (A) and (B) are explanatory diagrams of a crystal resonator 20 according to a second embodiment. (A) and (B) are explanatory diagrams of the crystal oscillator of the third embodiment, and are explanatory diagrams of the base 31 having another structural example 31a of the stress relaxation structure part in particular. (A) and (B) are explanatory diagrams of a crystal oscillator according to a fourth embodiment, and are explanatory diagrams of a base 41 having still another structural example 41a of a stress relaxation structure part in particular. (A) to (C) are diagrams for explaining conventional techniques and problems.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the crystal resonator of the present invention will be described below with reference to the drawings. It should be noted that each drawing used for explanation is only schematically shown to the extent that the present invention can be understood. In addition, in each drawing used for explanation, the same reference numerals are given to the same components in the conventional art and the present invention, and the explanation thereof may be omitted. Also, the shapes, dimensions, materials, etc. described in the following description are merely preferred examples within the scope of the present invention. Therefore, the present invention is not limited only to the following embodiments.

1. First Embodiment FIG. 1 is an explanatory diagram of a crystal resonator 10 according to a first embodiment. In particular, FIG. 1(A) is a front view showing a part of the crystal resonator 10 cut away, FIG. 1 is a top view shown in FIG.

The crystal resonator 10 of the first embodiment includes a base 11 and a cover 53 that are sealed by a cold weld method, and a crystal resonator element 55 mounted inside the base 11 and the cover 53. In the second embodiment, the side wall of the base 11 is provided with a stress relaxation structure 11a. In the example of FIG. 1, the present invention is applied to a so-called NC-18 type (HC-43/U type) crystal resonator.
In the case of the crystal resonator 10 of the first embodiment, the stress relaxation structure portion 11a is configured by an uneven structure formed on the side wall of the base 11. As shown in FIG. Moreover, in this uneven structure, the unevenness is continuous along the height direction of the base 11 (the Y direction in FIG. 1(A)), and each of the protrusions and recesses is perpendicular to the height direction of the base. It has a structure extending in the (X direction in FIG. 1(A)). The pitch of the unevenness is preferably an arbitrary pitch in consideration of the effect of reducing stress and the ease of manufacturing the base 11 itself. In addition, it is important to consider the gap G between the side wall of the base 51 and the inner wall of the cover 53 so that the convex portion does not come into contact with the inner wall of the cover 53 . Although the gap G is not limited to this, it is generally 0.01 to 0.02 mm.

In the crystal resonator 10 of the first embodiment, the flange 51e of the base 11 and the flange 53a of the cover 53 are sealed by applying a high pressure to produce metal-to-metal bonding. Since the unevenness of the stress relaxation structure portion 11a is aligned along the direction (the Y direction in FIG. 1A) in which the stress generated at the joint with the cover 53 extends to the crystal vibrating piece 55, the stress relaxation effect is likely to occur. Conceivable.

2. Second Embodiment FIGS. 2A and 2B are diagrams for explaining a crystal resonator 20 according to a second embodiment, particularly FIG. 2A being a plan view thereof and FIG. 2B being a front view thereof.
The crystal resonator 20 of the second embodiment is obtained by applying the stress relaxation structure portion 11a of the first embodiment to the crystal resonator 20 having a structure in which the crystal resonator plate 55 is horizontally mounted on the base 21 . That is, the present invention is applied to so-called TO5 (eg, HC-35/U) type structures.
Therefore, the base 21 has four supporters 51d arranged at an angle of 90 degrees in plan view. A side surface of the base 21 is provided with a stress relaxation structure 11a similar to that of the first embodiment. The crystal vibrating piece 55 is fixed with a conductive adhesive 57 to the four supporters 51d.

3. Third Embodiment FIG. 3 is an explanatory diagram of a crystal resonator according to a third embodiment. It is a diagram focusing particularly on the base 31 and the stress relaxation structure portion 31a according to the third embodiment. 3(A) is its plan view, and FIG. 3(B) is its front view. However, illustration of the supporters and the like shown in FIGS. 1 and 2 is omitted in FIG.
In the base 31 according to the third embodiment, the stress relaxation structure portion 31a has continuous unevenness along the direction perpendicular to the height direction of the base 31 (the X direction in FIG. 3B), and , the projections and the recesses extend in the height direction of the base (the Y direction in FIG. 3(B)). That is, the structure is such that the unevenness is arranged in a direction orthogonal to the uneven arrangement structure of the first embodiment.
The pitch of the unevenness is preferably an arbitrary pitch in consideration of the effect of reducing stress and the ease of manufacturing the base 31 itself. It is considered that even with the stress relaxation structure portion 31a of the third embodiment, the influence of the sealing stress can be reduced.

4. Fourth Embodiment FIG. 4 is an explanatory diagram of a crystal resonator according to a fourth embodiment. It is a diagram focusing particularly on the base 41 and the stress relaxation structure portion 41a according to the fourth embodiment. 4A is a plan view thereof, and FIG. 4B is a front view thereof. However, illustration of the supporters and the like shown in FIGS. 1 and 2 is omitted in FIG.
The base 41 according to the fourth embodiment is an example in which the stress relaxation structure portion 41a is configured by a circular, elliptical, or polygonal concave-convex structure randomly provided on the side wall of the base 41 . In the example of FIG. 4, the structure is such that circular protrusions are randomly provided on the sidewalls of the base 41 .
The planar size and number of the projections are preferably set to an arbitrary size and number in consideration of the effect of reducing stress and the ease of manufacturing the base 41 itself.

In the above-described embodiments, the stress relaxation structure provided on the side wall of the base is a structure in which the outer surface of the header is uneven (see, for example, the cross section of the header 51a in FIG. 1A). However, a stress relaxation structure in which the inner side surface of the header is an uneven surface, or a stress relaxation structure in which both the outer side surface and the inner side surface of the header are uneven surfaces may be used. However, considering the ease of forming the uneven surface, it is preferable that the outer surface of the header be the uneven surface.

10: crystal resonator of the first embodiment, 11: base, 11a: stress relaxation structure,
20: Crystal oscillator of the second embodiment 21: Base 30: Base according to the third embodiment 31: Base 31a: Stress relaxation structure 40: Base according to the third embodiment 41: Base 41a : Stress relaxation structure part 51a: Metal header 51b: Kovar glass 51c: Lead 51d: Supporter 51e: Flange 53: Cover 53a: Flange 55: Crystal vibrating piece 55a: Electrode for excitation 55b: Extraction electrode 57: Conductivity glue

Claims (5)

A crystal oscillator comprising a base and a cover sealed by a cold weld method, and a crystal resonator element mounted in the base and the cover, wherein a side wall of the base is provided with a stress relaxation structure. A crystal oscillator characterized by 2. The crystal oscillator according to claim 1, wherein the stress relaxation structure is a concave-convex structure formed on the side wall. The concave-convex structure is characterized in that the concave-convex structure is continuous along the height direction of the base, and each of the convexes and concaves extends in a direction perpendicular to the height direction of the base. The crystal oscillator according to claim 2. The concave-convex structure is characterized in that the concave-convex structure is continuous along a direction perpendicular to the height direction of the base, and each of the convexes and concaves extends in the height direction of the base. The crystal oscillator according to claim 2. 3. The crystal oscillator according to claim 2, wherein the concave-convex structure is a circular, elliptical, or polygonal concave-convex structure randomly provided on the side wall.

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