JP2003060473A - Surface-mounted quartz oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-mounted quartz oscillator which can select its optimum holding position, regardless of the cutting direction or the kind of its quartz piece. SOLUTION: The surface-mounted quartz oscillator has a surface-mounting type base, having a rectangular storing portion; at least a pair of holding portions formed along the opposite sides to each other of the storing portion; holding electrodes formed on the holding portions; and a rectangular quartz piece, corresponding to the storing portion and supported by the holding portions, where its excitation electrodes formed on its plate surfaces are fixed and made to have continuity with the holding electrodes in at least two symmetrical places, relative to the center of the storing portion so as to obtain its proper stress sensitivity characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type crystal unit capable of selecting an optimum holding position in accordance with a cutting direction of a crystal piece with respect to a crystal axis or a type of a vibration mode of a crystal unit. .

[0002]

2. Description of the Related Art Generally, in a crystal oscillator, an electrode is formed on a plate surface of a crystal piece cut out in a plate shape at a predetermined angle with respect to a crystal axis of a crystal of an artificial crystal, and a lead end of the electrode is electrically conductively bonded. It is fixed with an agent to achieve mechanical retention and electrical continuity. On the other hand, in a crystal resonator, there is a phenomenon called a so-called stress sensitivity characteristic in which the amount of change in the resonance frequency with respect to external stress changes in accordance with the relationship between the crystal axis of the crystal piece and the holding position.

For this reason, in the crystal resonator, the direction in which the frequency change amount is smallest with respect to external stress is held. Also, in the case of a rectangular crystal piece, it is generally 2
From the viewpoint of stress sensitivity, it is desirable that the direction that holds the corners of the place and that connects the holding positions coincide with the direction in which the frequency change is smallest with respect to external stress. Therefore, the holding member provided in the container for storing the crystal piece is arranged at a position corresponding to the corner of the crystal piece.

However, in the case of a small crystal oscillator, a relatively large crystal of artificial quartz is cut into a plate shape and polished into a single crystal plate having a predetermined thickness, and the crystal plate is further cut into a plurality of pieces. Thus, a plurality of crystal pieces can be efficiently obtained. In such a case, when cutting the crystal plate into a plurality of crystal pieces, if the effective use of the area of the crystal plate is prioritized, the direction connecting the corners of the crystal piece, which is the holding site, becomes a desirable direction from the viewpoint of stress sensitivity. Inconsistencies may occur.

Further, depending on the type of crystal piece, that is, the vibration mode, the direction in which good stress sensitivity characteristics can be obtained also differs.
For example, in an AT-cut thickness-slip crystal oscillator, as shown in FIG.
It is desirable to hold the crystal piece at the intersection of the straight line rotated by 8 ° and the edge of the crystal piece. Similarly, in the SC cut crystal unit, as shown in Fig. 4, Z'is passed through the center of the plate surface.
It is desirable to hold the quartz crystal at a position where the straight line rotated about 8 ° from the axis to the X ′ axis intersects with the edge of the quartz crystal.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a surface mount type crystal resonator capable of selecting an optimum holding position regardless of the cutting direction or the type of the crystal piece. It is intended to provide.

[0007]

According to a first aspect of the present invention, there is provided a surface mount type base having a rectangular accommodating portion, and at least a pair of holding portions formed along sides of the base facing the accommodating portion. , The holding electrode formed on the holding portion and the excitation electrode carried on the holding portion and formed on the plate surface are fixed to the holding electrode at at least two points symmetrical with respect to the center with good stress sensitivity characteristics. And a rectangular crystal piece corresponding to the above-mentioned accommodating portion that is electrically connected to the surface mount type crystal resonator.

According to a second aspect of the present invention, in the structure according to the first aspect, the position where good stress sensitivity characteristics can be obtained is within ± 3 ° of the best position of stress sensitivity characteristics. A third aspect of the present invention is a surface mount type crystal unit, wherein the crystal element is A.
It is a T-cut, and the crystal piece is fixed to the holding electrode at the intersection of a straight line passing through the center of the plate surface of the crystal piece and rotated about 28 ° from the Z'axis in the X-axis direction to one edge of the crystal piece. It is a characteristic surface mount type crystal unit.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the crystal piece is SC cut and passes through the center of the plate surface of the crystal piece about 8 ° from the Z'axis to the X'axis direction. It is a surface-mount type crystal unit in which a crystal piece is fixed to a holding electrode at a portion where a rotated straight line intersects with one edge of the crystal piece.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described in detail with reference to an assembly perspective view shown in FIG. 1 and a plan view shown in FIG. 2 by taking a case using a square container and a crystal piece as an example. To do.

In the figure, reference numeral 1 is a square base made of ceramic. This base is provided with a square storage part 2 having an open top surface. And the holding | maintenance part 3 is provided in four circumferences along the inner wall of the accommodating part 2.

Then, on the upper surfaces of the pair of holding portions 3 facing each other,
The holding electrodes 4 are formed so as to be insulated from each other. The holding electrode 4 is electrically connected to a mounting electrode formed on the bottom surface of the base 1. The crystal piece 5 is carried on the upper surface of the holding portion 3. The crystal piece 5 has an excitation electrode 6 formed at the center of the front and back plate surfaces, the excitation electrodes 6 are led out in opposite directions to the plate surface end portion, and are further extended over the entire length of the side of the lead-out end. .

Therefore, as shown in the plan view of FIG. 2, for example, the excitation electrodes 6 of the crystal blank 5 are formed over substantially the entire length of the sides facing each other. Here, the holding position where good stress sensitivity characteristics can be obtained differs depending on the type of the crystal piece 5, that is, the vibration mode, the cutting direction from the crystal plate, or the like.

For example, when the crystal piece 5 is an AT-cut thickness slip oscillator, it is most desirable from the viewpoint of stress sensitivity to hold the quartz piece 5 in a direction rotated by about 28 ° from the Z'axis as shown in FIG. If the crystal piece 5 is an SC cut crystal unit,
From the viewpoint of stress sensitivity, it is most desirable to hold in the direction rotated by about 8 ° from the Z'axis as shown in FIG.

Therefore, the holding electrodes 4 provided in the housing portion 2 are formed over substantially the entire length of the sides facing each other. Therefore, by applying the conductive adhesive 7 to any position on this side, it can be fixed at any position. In this case, in actual products, it is difficult to maintain the stress sensitivity characteristics in the most desirable direction due to errors in manufacturing and assembling.

Then, the top opening of the base is hermetically sealed with a lid (not shown) in an atmosphere of vacuum, an inert gas or the like. Then, the mounting electrodes on the bottom surface of the base can be mounted on the conductive pattern of the printed board by soldering or the like for use.

With this configuration, the frequency change can be minimized with respect to the external stress applied to the crystal unit, and the best frequency stability can be obtained. In addition, it is possible to store various types of crystal pieces at the optimal holding position with one type of base, and by sharing the base part, it is possible to use high-quality and inexpensive members and reduce costs. it can.

The present invention is not limited to the above-described embodiment. For example, the storage part of the base and the crystal piece are not limited to the square shape, and it is sufficient if the crystal piece can be stored in the storage part. It may be rectangular.

[0019]

As described in detail above, according to the present invention,
A single type of base can hold a wide variety of crystal pieces at the best holding position for stress sensitivity characteristics, and the cost can be reduced by using common parts and using high-quality, inexpensive members. It is possible to provide a surface mountable crystal unit that can be manufactured.

[Brief description of drawings]

FIG. 1 is an assembled perspective view of an embodiment of the present invention.

FIG. 2 is a plan view of an embodiment of the present invention.

FIG. 3 is a diagram illustrating a stress sensitivity characteristic of an AT-cut crystal piece.

FIG. 4 is a diagram illustrating stress sensitivity characteristics of SC-cut crystal pieces.

[Explanation of symbols]

1 ... Base 2 ... Storage section 3 ··· Holding part 4 ・ ・ Holding electrode 5 · · Crystal pieces

Claims (4)

[Claims] 1. A surface-mounting type base having a rectangular housing portion, at least a pair of holding portions formed along sides of the base facing the housing portion, holding electrodes formed on the holding portion, and A rectangular shape corresponding to the storage part in which the excitation electrode, which is carried by the holding part and formed on the plate surface, has good stress sensitivity characteristics and is fixed to the holding electrode at at least two points symmetrical with respect to the center to make it conductive. 2. A surface mount type crystal unit, comprising: 2. The device according to claim 1, wherein the position where good stress sensitivity characteristics are obtained is within ± 3 ° of the position where the stress sensitivity characteristics are the best. Surface mount crystal unit. 3. The crystal piece according to claim 1, wherein the crystal piece is AT-cut, and a straight line passing through the center of the plate surface of the crystal piece and rotated by about 28 ° from the Z ′ axis to the X axis direction. A surface-mount type crystal resonator, wherein the crystal piece is fixed to a holding electrode at a portion intersecting with a peripheral portion of the crystal piece. 4. The straight line according to claim 1, wherein the crystal piece is SC-cut, and a straight line is passed through the center of the plate surface of the crystal piece and is rotated about 8 ° from the Z ′ axis to the X ′ axis direction. A surface-mount type crystal resonator, wherein the crystal piece is fixed to a holding electrode at a portion where the edge of the crystal piece intersects with the edge portion of the crystal piece.