JP2008294592A - Piezoelectric device for surface mounting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce height dimensions of a surface mounting crystal device hermetically sealed by seam welding. <P>SOLUTION: In the surface mounting piezoelectric device wherein at least a crystal piece 2 is stored in a recessed container main body 1 made of laminated ceramics and the extended outer peripheral part of a drawing electrode of the crystal piece 2 is fixed by a conductive adhesive 10 and a metallic cover 3 is joined to a metallic ring 6 provided to the opening end face of the container main body 1, the metallic ring 6 is partially buried in the opening end face of the container main body 1 and has its tip end side projected. Joining strength can be maintained same as conventional devices because of seam welding using the metallic ring. Since the metallic ring 6 is partially buried in the opening end face, height dimensions can be reduced. Since a part of the side face where the metallic ring 6 is buried is not exposed, electric short circuit to an excess portion of the conductive adhesive can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface mount piezoelectric device (hereinafter referred to as a surface mount device), and more particularly to a quartz crystal device hermetically sealed by seam welding.

(Background of the Invention)
Surface mount piezoelectric devices such as crystal resonators (hereinafter referred to as surface mount resonators) are small and light, so they are built into portable electronic devices such as mobile phones as a reference source for frequency and time. Is done. One of these is a surface-mounted vibrator that is hermetically sealed by seam welding.

(Example of conventional technology)
FIGS. 3A and 3B are diagrams for explaining a conventional example. FIG. 3A is a cross-sectional view of a surface mount vibrator, and FIG. 3B is a plan view of a crystal piece.

  The surface-mount oscillator is formed by housing a crystal piece 2 in a container body 1 having a concave shape and covering a metal cover 3 in a hermetically sealed manner. The container body 1 is made of a laminated ceramic of a bottom wall 1a and a frame wall 1b, and has a crystal holding terminal 4 on the inner bottom surface. The crystal holding terminal 4 is electrically connected to the mounting terminal 5 on the outer bottom surface which becomes a pair of diagonal portions, for example, through the laminated surface.

  A metal film (not shown) is provided on the opening end face of the container body 1, and a metal ring 6 for seam welding is joined by a silver solder 7. The metal film is connected to the mounting terminal 5 as the ground terminal on the outer bottom surface which is a diagonal portion of another set through the through hole 8 provided in the frame wall 1b of the container body 1 and the laminated surface.

The quartz crystal piece 2 has excitation electrodes 9a on both main surfaces, and extends extraction electrodes 9b on both sides of one end. Then, both ends of the extended end portion of the extraction electrode 9 b are fixed to the crystal holding terminal 4 of the container body 1 by the conductive adhesive 10. The metal cover 3 is joined to the metal ring 6 by seam welding using a pair of roller electrodes (not shown) to hermetically seal the opening surface. And it is set as the shield structure connected to the mounting terminal 5 as a ground terminal of an outer bottom face.
JP 2003-8288 A JP 11-31748 A JP 2004-297620 A

(Problems of conventional technology)
However, the surface-mounted vibrator having the above configuration has a problem that the height dimension becomes large because the metal ring 6 for seam welding is provided. From this, for example, it is conceivable to employ a direct seam using a metal thick film instead of the metal ring 6 (Patent Document 2). However, in this case, the bonding strength is reduced because of the bonding with the thick metal film. In addition, there is a problem that a pressing force is directly applied to the container main body 1 at the time of welding with the roller electrode to damage the container main body 1.

  Moreover, although there exists what used the frame wall 1b of the container main body 1 as a metal frame (patent document 3), the surplus of the conductive adhesive 10 adheres to a metal frame, and an electrical short circuit is produced in this case. There was a problem.

(Object of invention)
An object of this invention is to provide the surface mount device which can make a height dimension small.

  According to the present invention, at least a crystal piece is accommodated in a concave container body made of a laminated ceramic, and an outer peripheral portion of the extraction electrode of the crystal piece is fixed by a conductive adhesive, and provided on the opening end surface of the container body. In the surface mounting piezoelectric device in which a metal cover is bonded to the metal ring thus formed, a part of the metal ring is embedded in the opening end surface of the container body, and the tip side is projected.

  With such a configuration, since the seam welding uses a metal ring, the joining strength is maintained as usual. And since a part of metal ring is embed | buried in an opening end surface, a height dimension can be made small. In addition, since a part of the side surface where the metal ring is embedded is not exposed, an electrical short circuit with an excess of the conductive adhesive is prevented.

(Embodiment section)
In Claim 1, the outer peripheral part which the extraction electrode of the said crystal piece extended is made into a position lower than the opening end surface of the said container main body. Thereby, the electrical short circuit by the excess part of an electroconductive adhesive agent is prevented reliably.

  FIG. 1 is a view for explaining an embodiment of the present invention. FIG. 1 (a) is a cross-sectional view of a surface-mounted vibrator, and FIG. 1 (b) is a plan view of a container body. 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, the surface mount vibrator is made of the laminated ceramic of the bottom wall 1a and the frame wall 1b, and the crystal piece in which the extraction electrode 9b extends to the crystal holding terminal 4 provided on the inner bottom surface of the concave container body 1. Both sides of one end of 2 are fixed by the conductive adhesive 10. The crystal holding terminal 4 is connected to a mounting terminal 5 provided on the outer bottom surface of a pair of diagonal portions.

  And the metal cover 3 is joined to the metal ring 6 provided in the opening end surface of the container main body 1 by seam welding. The metal cover 3 is connected to a mounting terminal 5 as a ground terminal of another set of diagonal portions.

  The metal ring 6 for seam welding here is partially embedded in the opening end surface (frame wall end surface) of the container body 1 and the surface side protrudes from the opening end surface. Specifically, an annular groove 11 that circulates around the upper surface of the frame wall 1b is provided on the end surface of the frame wall 1b of the container body 1 by a mold, and through holes 12 are provided in the other diagonal portions. For example, tungsten (W) as a base electrode is printed on the inner surface of the groove 11 and the through hole 12 (so-called through hole 8).

  Then, a frame wall 1b in which tungsten is formed on the inner surface and has an annular groove 11 and a through hole 12 is laminated and fired on the bottom wall 1a on which the crystal holding terminal 4 and the base electrode made of W as a mounting electrode are formed. To do. After firing, for example, nickel (N) and gold (Au) are formed on the exposed tungsten by electrolytic plating. Thereafter, silver solder 7 is poured into the annular groove 11, and a part of the metal ring 6 is buried and joined.

  Then, both ends of one end portion of the crystal piece 2 from which the extraction electrode 9b extends are fixed to the crystal holding terminal 4 on the inner bottom surface by the conductive adhesive 10 as described above. In this case, the height of both sides of one end of the crystal piece 2 is lower than the upper surface of the frame wall 1b of the container body 1 (laminated ceramic), and here the conductive adhesive 10 and the upper surface of the frame wall 1b are also included. Lower position. Then, the metal cover 3 is joined to the metal ring 6 by seam welding using a pair of electrode rollers.

  With such a configuration, as described in the column of the effect of the invention, seam welding using the metal ring 6 is performed, so that the bonding strength with the metal ring 6 is maintained as usual. And since a part of metal ring 6 is embed | buried in the opening end surface of the container main body 1, a height dimension can be made small.

  Further, since some of the side surfaces embedded with the metal ring 6 are not exposed within the frame, an electrical short-circuit with the surplus of the conductive adhesive 10 is basically prevented. Here, since the extended outer peripheral portion of the extraction electrode 9b of the crystal piece 2 is positioned lower than the opening end surface of the container body 1 including the conductive adhesive 10, the electrical conductivity due to the excess of the conductive adhesive 10 Make sure to prevent short circuit.

(Other matters)
In the above embodiment, the metal ring 6 is embedded in the opening end surface. However, as shown in FIG. 2, for example, the outer surface of the metal ring 6 may be exposed. Here, it is assumed to be buried including this case. Further, although the surface mount vibrator has been described as an example, for example, a surface mount oscillator in which the crystal piece 2 is housed together with an IC chip that forms an oscillation circuit can be applied. In this case, the same applies to the case where the concave portions are provided on both main surfaces, the crystal piece 2 is accommodated in one concave portion, and the IC chip is accommodated in the other concave portion.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining one Embodiment of this invention, The figure (a) is sectional drawing of a surface mount vibrator | oscillator, The figure (b) is a top view of a container main body. It is sectional drawing of the surface mount vibrator explaining the other example of one Embodiment of this invention. It is a figure explaining one prior art example, the figure (a) is a sectional view of a surface mount vibrator, and the figure (b) is a top view of a crystal piece.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Container body, 2 Crystal piece, 3 Metal cover, 4 Crystal holding terminal, 5 Mounting terminal, 6 Metal ring, 7 Silver brazing, 8 Through hole, 9 Electrode, 10 Conductive adhesive, 11 Annular groove, 12 Through-hole .

Claims (2)

  A metal ring provided on the opening end surface of the container body, in which at least a crystal piece is accommodated in a concave container body made of a multilayer ceramic, and an outer peripheral portion of the crystal piece with the lead electrode extended is fixed by a conductive adhesive. A surface mounting piezoelectric device having a metal cover bonded to a surface thereof, wherein a part of the metal ring is embedded in the opening end surface of the container body and the tip side protrudes. .   2. The surface-mount piezoelectric device according to claim 1, wherein an extended outer peripheral portion of the extraction electrode of the crystal piece is located at a position lower than an opening end surface of the container body.

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