JP2001237665A - Surface mount container and crystal resonator using the same - Google Patents

Abstract

(57) [Summary] [Object] To provide a crystal resonator for surface mounting which prevents a frequency change upon impact. A surface mount container provided with a pair of terminal electrodes forming a gap with a crystal piece on both sides of one end of a bottom surface of the container, and a pillow provided on the other end of the bottom surface of the container to maintain the horizontality of the crystal piece. , The pillow portion is formed from an insulator.
Further, both ends of the extended quartz piece extending from the excitation electrode to the extraction electrode on the pair of terminal electrodes are electrically and mechanically connected to each other by a conductive bonding material, and the excitation electrode is close to an outer peripheral edge. The other end of the crystal piece is arranged on the pillow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mountable container and a crystal unit using the same in the industrial technical field, and more particularly, to a quartz crystal piece which is electrically and mechanically connected at both ends to a quartz piece. Related to a vibrator.

[0002]

BACKGROUND OF THE INVENTION Quartz resonators are widely used in various electronic devices, including communication devices, as frequency and time reference sources. In recent years, with the miniaturization of electronic devices, further reduction in the size of quartz resonators has been required.

(Example of Prior Art) FIG. 2 is a cross-sectional view of a quartz oscillator for explaining a conventional example. The crystal unit is formed by sealing a crystal blank 2 in a surface mount container 1. The surface mount container 1 is obtained by covering a container body 3 made of a multilayer ceramic with a cover 4 by resistance welding and glass or resin sealing. A pair of terminal electrodes 5 are provided on the bottom surface of the container body 3 on both sides at one end.
The other end has a pillow portion 6. These are formed by adding tungsten (W) to a ceramic green sheet when the container body 3 is formed.
Is formed integrally by printing and baking.

The crystal blank 2 is, for example, AT-cut, has excitation electrodes 7 on both main surfaces, and extends extraction electrodes 8 on both sides of one end (FIG. 3). Then, a pair of terminal electrodes 5 of the container body 3
The two ends of the crystal blank 2 are electrically and mechanically connected and held by a conductive adhesive 9. At this time, crystal piece 2
Is placed on the pillow section 6.

In such a device, the gap between the bottom surface of the container and the crystal blank 2 is provided by the thickness of the pair of terminal electrodes 5, so that the height dimension is smaller than that in the case where a step is provided on the side surface of the container. it can. In addition, since the other end of the crystal blank 2 is placed on the pillow portion 6, the work of applying the conductive adhesive 9 is facilitated, and at the time of impact, the swing width of the other end can be reduced to prevent breakage. .

[0006]

[Problems to be Solved by the Invention]
However, the crystal resonator having the above configuration has the following problem due to downsizing. That is, as the size of the crystal unit is reduced, the size of the crystal piece 2 sealed in the container body 3 is naturally reduced. On the other hand, the smaller the plate area, the more difficult the crystal blank 2 is to vibrate, and the larger the crystal impedance (hereinafter referred to as CI). Normally, as the crystal blank 2 becomes smaller, the area of the excitation electrode 7 is increased, and
Decrease I. Therefore, the excitation electrode 7 is formed close to the outer peripheral edge of the other end (FIG. 4).

However, such a method has a problem that a frequency change occurs at the time of impact or the like. That is, the other end of the crystal blank 2 swings up and down at the time of impact or the like, and repeats contact and non-contact with the pillow portion 6 on the bottom surface of the container. In this case, when the excitation electrode 7 is close to the outer peripheral edge of the other end, the excitation electrode 7 contacts the pillow portion 6. In addition, non-contact ones come in contact. Therefore, since the pillow portion 6 is a metallized layer made of tungsten and is conductive, the parallel capacitance (capacity between electrodes) C0 changes, causing a frequency change.

(Object of the Invention) It is an object of the present invention to provide a crystal resonator in which a frequency change is prevented.

[0009]

The basic solution of the present invention is that the pillow portion 6 on the bottom surface of the container is formed of an insulator.

[0010]

In the present invention, since the pillow portion 6 is made of an insulator, even if the other end of the crystal blank 2 changes contact or non-contact state, the charge between the pillow portion 6 and the excitation electrode 7 changes. Since no movement occurs, the capacitance between the electrodes is prevented from changing and is kept constant. Hereinafter, an embodiment of the present invention will be described.

FIG. 1 is a view of a crystal unit for explaining an embodiment of the present invention. The same parts as those in the prior art are denoted by the same reference numerals, and description thereof will be simplified or omitted. In the same manner as described above, both ends of the crystal piece 2 from which the extraction electrode 8 extends are connected to the pair of terminal electrodes 5 on the bottom surface of the container by the conductive adhesive 9.
Electrically and mechanically, the excitation electrode 7 is disposed on the pillow 6 at the other end formed near the outer peripheral edge.
The dashed line in the figure indicates the crystal blank 2. In this embodiment, the pillow 6 formed at the other end of the crystal blank 2 is an insulator made of ceramic. Specifically, a metallized layer made of tungsten as a terminal electrode 5 is formed on both sides of one end of a ceramic green sheet, and an insulating layer is formed as a pillow portion 6 on the other end, and integrally fired. The insulating layer is formed by mixing ceramic powder into a liquid. Further, in this example, the pillow portion 6 is formed at a central portion that does not face the mounting terminal 10 formed on the back surface.

With such a configuration, even if the contact state between the other end of the crystal blank 2 and the pillow portion 6 at the time of impact or the like changes, the movement of electric charges between the excitation electrode 7 and the pillow portion 6 can be achieved. There is no change in the capacitance between the electrodes. Therefore, a change in the vibration frequency is prevented. Further, in this example, the pillow portion 6 does not face the terminal on the back surface, so that almost no capacitance occurs between the terminal and the excitation electrode 7 having the bottom wall of the container as a dielectric. Therefore, a change in the vibration frequency is further prevented. This effect increases as the thickness of the bottom wall of the container decreases due to the reduction in thickness.

[0013]

[Other Matters] In the above embodiments, a quartz oscillator has been described. However, the present invention can also be applied to a case where a concave portion is provided on the back surface of the container body to accommodate a circuit element such as an IC and a crystal oscillator (not shown) is formed. In addition, the pillow portion 6 is formed integrally by applying and baking an insulating material. However, for example, after forming the container body, an insulating material such as a molten glass or an adhesive may be applied and cured.

[0014]

According to the present invention, since the pillow portion on the bottom of the container is made of an insulating material, it is possible to provide a crystal resonator in which a frequency change is prevented.

[Brief description of the drawings]

FIG. 1 is a plan view of a crystal unit, particularly a container body, for explaining an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a crystal unit illustrating a conventional example.

FIG. 3 is a plan view of a crystal piece illustrating a conventional example.

FIG. 4 is a plan view of a crystal blank for explaining a conventional example.

[Explanation of symbols]

1 surface mount container, 2 crystal pieces, 3 container body, 4 covers, 5 terminal electrodes, 6 pillows, 7 excitation electrodes, 8 extraction electrodes, 9 conductive adhesive, 10 mounting terminals.

Claims (2)

[Claims] 1. A surface provided with a pair of terminal electrodes forming a gap with a crystal blank on both sides of one end of a bottom surface of a container, and a pillow provided on the other end of the bottom surface of the container to maintain horizontality of the crystal blank. In a mounting container, the pillow portion is formed from an insulator. 2. The excitation electrode according to claim 1, wherein both ends of an extended crystal piece extending from the excitation electrode to the pair of terminal electrodes are electrically and mechanically connected by a conductive bonding material. Wherein the other end of the crystal piece close to the outer peripheral edge is arranged on the pillow portion.