JP2005229340A - Vessel for piezoelectric vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vessel for piezoelectric vibrators which is more inexpensive than before though having high vacuum and high airtightness. <P>SOLUTION: The vessel for piezoelectric vibrators is provided with a base which is made of laminated ceramics and forms a cavity structure and a lid which is sealed on the base and is made of metal, ceramics, or glass, and a piezoelectric vibrating piece is to be stored in the vessel for piezoelectric vibrators. A bottom of the base has a sealing hole connecting to the inside and the outside of the vessel for piezoelectric vibrators, and the sealing hole is provided in such a position that its aperture on the inside of the vessel for piezoelectric vibrators is partially closed by a part forming a side wall of the base, and the sealing hole is sealed up with a sealant. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a container for a piezoelectric vibrator that houses a piezoelectric vibrating piece.

  In recent years, electronic components used in these devices have been downsized and surface-mounted due to the reduction in thickness, weight, size and automatic mounting of small information devices and mobile communication devices such as PDAs, mobile phones, and digital cameras. It is progressing rapidly. Against this background, the number of SMD type piezoelectric vibrators that are sealed by covering a ceramic package with a lid such as metal is increasing (for example, see Patent Document 1 and Patent Document 2).

  3A and 3B are diagrams showing a conventional piezoelectric vibrator. FIG. 3A is a plan view, and FIG. 3B is a front sectional view. The piezoelectric vibrating reed 21 is aligned and mounted on electrode portions 24a and 24b formed on a base 22 made of a laminated ceramic body having a three-layer structure, and is electrically connected and fixed by a conductive adhesive. Next, the glass or metal lid 23 is aligned with the base 22 and is sealed with a sealing material 25 such as brazing material or low-melting glass by an electric furnace, a heating furnace or the like of the heating means (first sealing). Stop process). When the sealing material 25 in the first sealing process is heated and melted, the gas occluded in the sealing material 25 and the conductive adhesive or the gas adsorbed on the surface of the sealing material 25 is released, and this gas is piezoelectric. Residual inside the vibrator container 27 may deteriorate the characteristics of the piezoelectric vibrator. In order to prevent the deterioration of the characteristics due to the gas, the bottom plate of the base 22 is provided with a stepped hole 22a for discharging gas. Thereafter, a sealing material 26 made of a metal ball or the like is mounted in a gas discharge stepped hole 22a provided in the bottom plate of the base 22 in a vacuum atmosphere, and a laser device is formed in the same manner as in the first sealing step. Then, the sealing material 26 is melted by an electron beam device or the like to perform hermetic sealing (second sealing step). Here, the stepped hole 22a for gas discharge need not have a stepped shape only for gas discharge, but after sealing in the second sealing step, a sealing material 26 such as a metal ball is formed. In order not to drop off from the bottom plate of the base 22, the shape is stepped.

JP 2000-106515 A Japanese Patent Laid-Open No. 2002-9577

  The structure of a conventional container for a piezoelectric vibrator is hermetically sealed by providing a stepped hole in a base bottom plate for gas discharge and finally sealing the stepped hole. This stepped hole is formed by forming a base bottom plate made of a multilayer ceramic with a ceramic two-layer structure, and providing and overlapping through holes having different inner diameters in each layer. The base bottom plate having the ceramic two-layer structure has a disadvantage of high cost.

  The present invention has been made to solve the above-described drawbacks, and an object of the present invention is to provide a container for a piezoelectric vibrator that is less expensive than the conventional one while being highly vacuum and highly airtight.

  A piezoelectric vibrator container that includes a base made of a multilayer ceramic and forms a cavity structure, and a lid that is sealed with a sealing material at the top of the base, and stores a piezoelectric vibrating piece therein. Has a sealing hole that communicates the inside and the outside of the piezoelectric vibrator container, and the opening on the inner side of the piezoelectric vibrator container is partially blocked by the portion that forms the side wall of the base. The piezoelectric vibrator container is provided at a position and the sealing hole is sealed with a sealing material.

  According to the present invention, it is possible to obtain a structure in which the sealing material does not fall off from the bottom plate of the base after hermetic sealing, while the base plate of the multilayer ceramic has a single layer structure instead of a two-layer structure as in the past. A high-vacuum, air-tight and inexpensive piezoelectric vibrator container can be provided.

  The gist of the present invention is that a base plate made of a single layer ceramic is provided with a through hole for gas discharge, and a single layer ceramic that forms a base side wall is overlapped so as to be part of the through hole to form a cavity structure. The base structure is intended to provide a high-vacuum, air-tight and inexpensive piezoelectric vibrator container.

  Hereinafter, a container for a piezoelectric vibrator and a piezoelectric vibrator of the present invention will be described with reference to the drawings. 1A and 1B are diagrams showing a structure of a piezoelectric vibrator according to an embodiment of the present invention, in which FIG. 1A is a plan view, FIG. 1B is a front sectional view, and FIG. 1C is a side sectional view. FIG. 2 is an enlarged view of a portion A in FIG.

  Reference numeral 11 denotes a tuning-fork type piezoelectric vibrating piece provided with an excitation electrode, reference numeral 12 denotes a base for a piezoelectric vibrator container, and reference numeral 13 denotes a lid for hermetically sealing the piezoelectric vibrator container. The base 12 is made of a multilayer ceramic having a two-layer structure, and has a cavity structure in which a base bottom plate 12a is formed by a first ceramic layer and a base side wall portion 12b is formed by a second ceramic layer. A through hole is formed in the base bottom plate 12a, and a sealing hole 12c is formed by arranging the base side wall portion 12b so as to partially cover the through hole of the base bottom plate 12a. On the inner wall of the sealing hole 12c, a metal metallized layer and a Ni plating and Au plating layer 18 formed on the surface thereof are formed. The base bottom plate 12a is provided with electrodes 14a and 14b for establishing electrical connection between the tuning fork type piezoelectric vibrating piece 11 and the outside.

  First, the tuning fork type piezoelectric vibrating piece 11 is mounted in alignment on the electrodes 14a and 14b of the base 12, and is electrically connected and fixed with a conductive adhesive.

Thereafter, the oscillation frequency of the tuning fork type piezoelectric vibrating piece 11 is adjusted so as to obtain a desired oscillation frequency.
The adjustment of the oscillation frequency is performed by a method in which a metal electrode part is provided on the tuning fork type piezoelectric vibrator piece 11 and the weight of the tuning fork type piezoelectric vibration piece is reduced by evaporating the metal electrode part with a laser beam or the like. Next, the lid 13 made of metal, ceramic, or glass is aligned with the upper portion of the base 12, and the sealing material 15 such as brazing material or low melting point glass is melted by a laser device, an electron beam device, a heating furnace, or the like, Sealing (first sealing step). Here, the first sealing process and the adjustment process of the oscillation frequency may be mixed before and after the first sealing process as long as the material of the lid 13 is glass, etc. Absent.

  In the first sealing step, the gas adsorbed on the surface of the sealing material 15 and the gas occluded in the sealing material 15 remain in the piezoelectric vibrator container 17. This gas is a factor that deteriorates the characteristics of the piezoelectric vibrator. In order to remove this gas, the piezoelectric vibrator container 17 is heated to a high temperature in a vacuum atmosphere and discharged to the outside from the sealing hole 12c provided in the base bottom plate 12a. Thereafter, the sealing material 12 such as a metal ball is heated and melted in the sealing hole 12c, and the piezoelectric vibrator container 17 is hermetically sealed. When the sealing material 16 is placed in the sealing hole 12c, the sealing material 16 abuts against the base side wall portion 12a applied to the sealing hole 12c, and does not slip through the sealing hole 12c. The thing of the magnitude | size which does not protrude outside from the lower surface is used. This step becomes the second sealing step, and the piezoelectric vibrator is completed.

It is a figure which shows the structure of the piezoelectric vibrator in one Embodiment of this invention, (a) is a top view, (b) is front sectional drawing, (c) is side sectional drawing. The A section enlarged view of FIG.1 (c). It is a figure which shows the conventional piezoelectric vibrator, (a) is a top view, (b) is front sectional drawing.

Explanation of symbols

11 Tuning Fork Type Piezoelectric Vibrating Piece 12 Base 12a Base Bottom Plate 12b Base Side Wall 12c Sealing Hole 13 Lid 14a Electrode 14b Electrode 15 Sealing Material 16 Sealing Material 17 Piezoelectric Vibrator 18 Ni, Au Plated Layer 21 Tuning Fork Type Piezoelectric Vibration Piece 22 Base 22a Stepped hole 23 Lid 24a Electrode 24b Electrode 25 Sealing material 26 Sealing material 27 Piezoelectric vibrator container

Claims (1)

A piezoelectric vibrator container that includes a base made of a multilayer ceramic and forms a cavity structure, and a lid that is sealed with a sealing material at the top of the base, and in which a piezoelectric vibrating piece is housed. Has a sealing hole that communicates the inside and the outside of the piezoelectric vibrator container, and the opening on the inner side of the piezoelectric vibrator container is partially blocked by the portion that forms the side wall of the base. A piezoelectric vibrator container provided at a position, wherein the sealing hole is sealed with a sealing material.

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