JP2007306068A - Crystal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crystal device, especially a tuning fork resonator, that blockades the penetration section of a vessel body for maintaining the degree of vacuum satisfactorily. <P>SOLUTION: In the crystal device, at least a crystal chip 1 is stored in the insulating vessel body 2 for covering, and the penetration section 7 that is provided in the vessel body 2 and has a step is blockaded by metal in a vacuum atmosphere for vacuum sealing. In this case, a metal film made of Au is provided on the surface of the step at the penetration section 7, an annular projection 9a that is provided at the periphery of a metal plate 9 plated with Ni and rotates around the metal plate 9 comes into contact with the metal film, the metal film is joined to the annular projection 9a of the metal plate 9 by resistance welding for energizing between the metal film and the metal plate 9, and the penetration section 7 is blockaded. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a crystal device that is vacuum-sealed (vacuum sealed), and more particularly to a tuning-fork crystal resonator (hereinafter referred to as a tuning-fork resonator) having a crystal piece as a tuning fork.

(Background of the Invention)
While the tuning fork vibrator is known as a reference source for measuring the rate, it is also used as a synchronization signal source. In such a case, since a pair of tuning fork arms vibrate in the horizontal direction, for example, when encapsulated in gas, a frictional resistance is generated, and crystal impedance (CI) is deteriorated. For this reason, the CI is reduced by vacuum sealing.

(Example of the first and second prior arts)
3A is a sectional view of a tuning fork vibrator showing an example of the second prior art, FIG. 3B is a front view of a crystal piece, and FIG.

  In both cases of the first and second prior arts, the tuning fork type vibrator accommodates a crystal piece 1 in the shape of a tuning fork in a container body 2. The container body 2 is made of a laminated ceramic and has an inner wall step portion as a concave shape. The crystal piece 1 is, for example, a Z-cut, and a pair of tuning fork arms 1 (ab) are extended from the tuning fork base 1c. Excitation electrodes 3 for exciting tuning fork vibration are formed on the four surfaces of each tuning fork arm.

  One main surface of the tuning fork base 1c has a pair of extraction electrodes (not shown) extending from the excitation electrode 3 and connected in common. One main surface of the tuning fork base portion 1 c extending from each extraction electrode is fixed to the inner wall step portion of the container body 1 by the conductive adhesive 4. Each extraction electrode is electrically connected to the mounting terminal 5 on the outer bottom surface of the container body 2 through the laminated surface.

(First prior art)
In the first prior art, the metal cover 6 is joined to the metal ring 2a provided on the opening end surface of the container body 2 by seam welding in a vacuum atmosphere. In the seam welding, a pair of electrode rollers (not shown) are pressed against both opposite sides of the metal cover 6 and energized between the pair of electrode rollers.

  Then, the metal roller is relatively advanced, and both sides of one set of the metal cover 6 are joined by Joule heat by energization, and then both sides of the other set are joined in the same manner. Normally, the base material of the metal cover 6 is Kovar whose expansion coefficient is close to the container body 2 (ceramic), and the surface is Ni plated. The Ni plating is melted and joined by Joule heat. Thereby, the crystal piece 1 is vacuum-sealed in the sealed container.

(Second conventional technology)
In the second prior art, the metal cover 6 is joined to the container body 2 by seam welding in the atmosphere. Then, the through-hole 7 provided on the bottom surface of the container body 2 is closed by the metal 8 in a vacuum atmosphere in which the air inside the container body 2 is exhausted. The through portion 7 includes a first through hole 7a on the outer surface side and a second through hole 7b on the inner bottom surface side having a smaller diameter, thereby forming a step. Then, a metal film familiar with ceramics such as W (tungsten) and Mo (molybdenum) is formed.

Then, a metal plate is joined by melting a sealant such as silver solder or solder. Alternatively, the metal itself is heated and melted to close it. These melt | dissolve a sealing agent and a metal with a heating apparatus by irradiation of a laser or an electron beam, for example. Thereby, the crystal piece 1 is vacuum-sealed in the sealed container.
Japanese Patent Laid-Open No. 11-312948 (paragraphs 0041 and 0076, FIGS. 1 and 10)

(Problems of conventional technology)
However, in the tuning fork vibrator according to the first prior art, seam welding is performed in a vacuum atmosphere in which a pair of metal rollers are rotated and sequentially joined. Therefore, the metal cover 6 is heated by Joule heat, and unnecessary gas is generated. And unnecessary gas was confined in the airtight container, and there existed a problem of reducing a vacuum degree.

  In the second prior art, the effect of unnecessary gas from the metal cover 6 during seam welding is reduced, but the sealant and the metal itself are melted. Accordingly, there is still a problem that the degree of vacuum is still lowered by the unnecessary gas generated from these. Accordingly, in any case, there is a problem that the CI of the tuning fork vibrator is increased.

(Object of invention)
An object of the present invention is to provide a crystal device, particularly a tuning fork type vibrator, in which a penetrating portion is closed to maintain a good degree of vacuum.

  In the present invention, as shown in the claims (Claim 1), at least a crystal piece is accommodated in a container body made of laminated ceramic and covered, and a through portion having a step provided in the container body is provided. In a quartz device sealed with metal in a vacuum atmosphere and vacuum sealed, a metal film made of Au is provided on the surface of the step in the penetrating portion, and a metal plate plated with Ni on the metal film An annular projection provided on the outer periphery of the metal plate is abutted, and the metal film and the annular projection of the metal plate are joined by resistance welding that energizes between the metal film and the metal plate, and the through portion is formed. The configuration is closed.

  In such a configuration, the Ni plating of the annular projections of the metal plate is melted and joined to the metal film by resistance welding, so compared with the case where the sealant such as silver solder or solder and the metal itself are heated and melted. Furthermore, the generation of unnecessary gas is further suppressed. Accordingly, the CI of the tuning fork vibrator can be reduced while maintaining a good degree of vacuum.

(Embodiment section)
According to claim 2 of the present invention, in claim 1, a protrusion for positioning is provided in a central region of the metal plate. In the third aspect of the present invention, in the first aspect, the container main body is a crystal resonator in which only a crystal piece is accommodated. In the fourth aspect of the present invention, in the third aspect, the crystal piece is a tuning fork type crystal resonator having a tuning fork shape. These make the present invention more concrete.

  FIG. 1 is a view for explaining an embodiment of the present invention. FIG. 1 (a) is a sectional view of a tuning fork type vibrator, FIG. 1 (b) is an enlarged sectional view of a portion indicated by a dotted circle, and FIG. ) Is a partially enlarged cross-sectional view illustrating resistance welding. In addition, the same number is attached | subjected to the same part as a prior art example, and the description is simplified or abbreviate | omitted.

  As described above, in the tuning fork vibrator, one main surface of the tuning fork base 1c with the extraction electrode extended is fixed to the inner wall step portion of the container body 2, and the metal cover 6 is joined by seam welding or the like. And in this invention, the penetration part 7 which has the level | step difference provided in the bottom face of the container main body 2 is obstruct | occluded by the resistance welding of the metal plate 9. FIG. As described above, the through portion 7 includes the first through hole 7a and the second through hole 7b, thereby forming a step.

  Here, the Ni and Au metal films 10 are laminated on the stepped surface of the penetrating portion 7 of the container body 2 using W or Mo as a base layer. The metal film 10 has an annular shape that goes around the through portion 7. The underlayer of W or Mo is formed by printing in the form of a green sheet forming a multilayer ceramic, and is fired integrally.

  The metal plate 9 is disc-shaped and has an annular protrusion 9a that circulates around the outer periphery of one main surface. And the protrusion part 9b below the diameter of the 2nd through-hole 7b is provided in the center part. These are formed by pressing or etching a metal flat plate. The surface of the metal plate 9 is Ni plating with the base material being Kovar.

  In such a case, first, the protruding portion 9 b of the metal plate 9 is inserted into the second through hole 7 b, and the outer peripheral annular protrusion 9 a is brought into contact with the metal film 10 on the stepped surface of the through portion 7. In this case, the metal plate 9 can be easily positioned by the protruding portion 9b. Next, the welding electrode rod 11 composed of the rod-shaped central electrode 11a and the cylindrical outer peripheral electrode 11b is pressed against the stepped surface of the penetrating portion 7 and energized. However, the tip of the central electrode 10 a of the welding electrode rod 11 is in contact with the metal plate 9, and the tip of the outer peripheral electrode 11 b is in contact with the metal film 10.

  As a result, a current is generated between the outer periphery of the metal plate 9 and the electrode film 10, and the current is concentrated particularly on the annular projection 9a, so that the Ni plating on the surface is melted by Joule heat. Then, the annular protrusion 9a of the metal plate 9 and the metal film 10 are joined. In this case, the Ni plating of the annular protrusion 9a is instantaneously melted and joined.

  Therefore, as in the conventional example, generation of unnecessary gas is suppressed as compared with the case where solder or silver solder as a sealing material is melted by heating or the metal itself is melted. Thereby, the degree of vacuum of the sealed container can be increased and the CI of the tuning fork vibrator can be reduced. As the outer diameter of the positioning projection 9b approaches the inner diameter of the second through-hole 7b, even if metal debris is generated by resistance welding, for example, entry into the sealed container can be prevented.

(Other matters)
In the above embodiment, the protrusion 9b for positioning is provided at the center of the metal plate 9. However, for example, it may be as shown in FIG. That is, the metal film 10 on the surface of the step is separated from the second through hole 7 b to form the electrodeless portion 10 a, and the first protruding portion 9 b and the second protruding portion 9 c are provided in the central region of the metal plate 9.

  And the 1st protrusion part 9b is inserted in the 2nd through-hole 7b, and the surface of the 2nd protrusion part 9c is contact | abutted to the electrodeless part 10a. If it does in this way, since the 2nd protrusion part 9c will contact | abut to the non-electrode part 10a and an electric current will not arise, a metal scrap will not generate | occur | produce from the 2nd protrusion part 9c. Therefore, the annular protrusion 9a is resistance-welded to the metal film 10, and even if metal scraps are generated from the annular protrusion 9a, entry into the sealed container can be prevented (so-called splash countermeasure).

  Although a tuning fork type vibrator has been described as an example, for example, an AT-cut thickness slip vibrator may be used, and any vibrator can be applied. Further, for example, an oscillator may be configured by hermetically enclosing the IC chip together with the crystal piece, and the present invention can be applied to a crystal device in which at least the crystal piece is hermetically sealed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an embodiment of the present invention, where FIG. 1A is a cross-sectional view of a tuning fork vibrator, FIG. 1B is an enlarged cross-sectional view of a portion indicated by a dotted circle, and FIG. It is a partially expanded sectional view explaining these. FIG. 6 is a partially enlarged cross-sectional view of a tuning fork vibrator for explaining another example of the present invention. FIG. 4A is a sectional view of a tuning fork vibrator showing an example of the first prior art, FIG. 2B is an example of the second prior art, and FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Crystal piece, 2 Container body, 3 Excitation electrode, 4 Conductive adhesive agent, 5 Mounting terminal, 6 Metal cover, 7 Penetration part, 8 Metal, 9 Metal plate, 10 Metal film, 11 Welding electrode rod

Claims (4)

  In a quartz crystal device in which at least a crystal piece is accommodated in a container body made of a multilayer ceramic and covered with a cover, a through portion having a step provided in the container body is closed with a metal in a vacuum atmosphere, and vacuum sealed, A metal film made of Au is provided on the surface of the step in the penetrating portion, and an annular projection provided on the outer periphery of a Ni-plated metal plate is brought into contact with the metal film, and the metal film and the A quartz crystal device characterized in that the metal film and an annular protrusion of the metal plate are joined by resistance welding that energizes between the metal plate and the penetrating portion is closed.   The quartz crystal device according to claim 1, wherein a protrusion for positioning is provided in a central region of the metal plate.   2. The quartz crystal device according to claim 1, wherein the container main body is a quartz crystal resonator in which only a crystal piece is accommodated.   4. The quartz crystal device according to claim 3, wherein the quartz crystal piece is a tuning fork type crystal resonator having a tuning fork shape.