JP2003133886A - Crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mounted oscillator whose impact resistivity is satisfactory capable of preventing frequency change before and after drop impact. SOLUTION: The both sides of one edge of a crystal piece whose outlet electrode is extended from an excitation electrode are fixed by conductive adhesive to the bottom face of a recessed container body, and the opening face of the container body is sealed with a cover so that a crystal oscillator can be constituted. In this case, the central region of the crystal bar whose outlet electrode is extended between the conductive adhesive for fixing the both sides of one edge of the crystal bar is fixed by insulating adhesive. Also, a metallic cove is used for the cover, and the conductive adhesive is applied only to the lower face including the side faces of the crystal bar.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial technical field of a crystal resonator for surface mounting (referred to as a surface mount resonator), and particularly, a surface mount resonator in which both ends of a crystal piece are fixed and held. Regarding

[0002]

(Background of the Invention) Surface mount oscillators are small
Because of its light weight, it is used as a frequency source and a time reference source especially in electronic devices including portable communication devices. In recent years, there has been a problem of impact resistance as the height of the body is reduced.

(Example of Prior Art) FIG. 4 (ab) is a diagram of a crystal unit for explaining a conventional example. FIG. 4 (a) is a sectional view and FIG. 4 (b) is a plan view excluding a cover. is there. The surface mount oscillator is formed by hermetically sealing a crystal piece 2 in a surface mount container 1. The surface mount container 1 includes a concave container body 3 made of laminated ceramics and a metal cover 4. The container body 3 has crystal terminals 5 on both sides of one end of the bottom surface of the recess, and at least a pair of mounting electrodes 6 electrically connected to the crystal terminals 5 are provided on the bottom surface and side surfaces of the outer surface. It also has a mounting electrode 6 which is electrically connected to the metal cover 4 and has a ground potential. The pillow 7 is provided on the other end of the bottom surface of the recess.

The crystal piece 2 is, for example, AT-cut, and the extraction electrodes 9 are formed on both sides of one end of the excitation electrode 8 formed on both main surfaces.
Extend. Each extraction electrode 9 is formed by folding back on the opposite surface. Then, the conductive adhesive 1 is attached to the crystal terminals 5 on the bottom surface of the recess on both sides of one end of the crystal piece 2 from which the extraction electrode 9 extends.
It is fixedly held by 0 and connected electrically and mechanically. Further, the other end portion is arranged on or in close contact with the pedestal 7.

The conductive adhesive 10 is applied to the bottom surface of the container body 3 and one end thereof is placed, and then applied from the top surface of the crystal piece 2 and is fixed by thermosetting. The metal cover 4 is joined to the metal ring or the metal film 11 formed on the upper surface of the side wall of the container body 3 by, for example, seam welding, and seals the opening surface.

In such a structure, since both ends of the crystal piece 2 are held, the generation of stress in the longitudinal direction caused by the curing shrinkage of the conductive adhesive 10 is prevented. This allows
Particularly, the frequency-temperature characteristic of the cubic piece 2 which is a cubic curve is favorably maintained. A flexible adhesive is selected as the conductive adhesive 10. Moreover, when the crystal piece 2 is made into a convex shape or the both ends are beveled, the pillow 7 has the crystal piece 2
Is formed because the central region of the is not in contact with the bottom surface of the recess.
Further, due to the commonality of parts, it is used even when the crystal piece 2 is flat.

[0007]

Problems to be Solved by the Invention (Problems of Prior Art)
However, the crystal oscillator having the above configuration has a problem in that the vibration frequency changes after a drop impact. That is, there is a problem that the vibration frequency changes when the crystal resonator completed by covering the metal cover 4 is dropped onto concrete, for example.

(Elucidation and Consideration of Problems) As a result of elucidation of the above problems, the following facts were found. That is, the other end, which is the free end of the crystal blank 2, fluctuates (vibrates) at the time of a drop impact, affecting the conductive adhesive 10 on both sides of the one end, for example, the strain during thermosetting is eliminated, and Change. Therefore, since the holding state changes before and after the impact, the vibration frequency changes due to the holding system.

The other end of the crystal piece 2 is moved between the pedestal 7 and the metal cover 4 and the conductive adhesive 10 is deformed, so that the other end of the crystal piece 2 is moved to the metal cover 4. It moves to the side and is held diagonally upward at a minute angle. Therefore, the substantial gap between the excitation electrode 8 on the upper surface of the crystal piece 2 and the metal cover 4 becomes smaller than that before the drop impact, the stray capacitance between them increases, and the vibration frequency changes due to the electric system. It has been found.

A further consideration of these points causes the following. That is, in order not to impair the vibration characteristics including the frequency temperature characteristics of the crystal unit on both sides of one end of the crystal piece 2,
It is fixed by a flexible conductive adhesive 10. Accordingly, the state of the conductive adhesive 10 on both sides of the one end changes due to the swinging of the other end during the drop impact.

From these facts, the distance between the crystal piece 2 and the metal cover 4 is reduced to limit the swinging width of the other end, so that the conductive adhesive 10 on both sides of the one end of the crystal piece 2 is subjected to a drop impact. It was considered that no stress was generated. However, in this case, the conductive adhesive 10 may come into contact with the metal cover 4. Therefore, it has been considered to apply the conductive adhesive 10 only to the lower surface of the crystal blank 2, but in this case, there is a problem that the connection strength is impaired.

(Object of the Invention) It is an object of the present invention to provide a surface-mounted oscillator having good impact resistance in which the frequency change before and after a drop impact is prevented.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a conductive adhesive 10 is formed by fixing both ends of one end of a crystal piece 2 from which an output electrode extends.
The basic solution is to fix the central region of the crystal element 2 between the two parts with the insulating adhesive 12 (corresponding to claim 1, FIG. 1). Further, the cover is the metal cover 4, and the conductive adhesive 10 is applied only to the lower surface including the side surface of the crystal piece 2 (corresponding to claim 2, FIG. 2).

[0014]

In the present invention, since the central regions on both sides of the extended one end of the extraction electrode 9 are fixed by the insulating adhesive 12,
Basically, the fixing strength at the time of drop impact is maintained (Claim 1). Further, since the conductive adhesive 10 is only on the lower surface including the side surface of the crystal blank 2, the gap between the crystal blank 2 and the metal cover 4 is reduced to suppress the swing width of the other end of the crystal blank 2, and An electrical short circuit with the metal cover 4 is prevented (Claim 2).
An embodiment of the present invention will be described below.

[0015]

[First Embodiment] FIG. 1 is a plan view of a surface mount vibrator excluding a cover for explaining a first embodiment of the present invention. In addition,
The same parts as those of the conventional example are given the same numbers, and the description thereof will be simplified or omitted. As described above, the surface-mounted oscillator has one end of the crystal piece 2 in which the other end abuts or approaches the pedestal 7 on the bottom surface of the recess of the container body 3 having the mounting electrode 6 and the extraction electrode 9 extends. Fix both sides with conductive adhesive 10,
The metal cover 4 is seam welded and hermetically sealed. Then, in this embodiment, the insulating adhesive 12 is applied to the central region where the crystal blank 2 (material) in the middle of both ends of the crystal blank 2 is exposed. The insulating adhesive 12 is selected to have a higher adhesive strength than the conductive adhesive 10, and is applied from the lower surface and the upper surface of the crystal piece 2 like the conductive adhesive 10.

With such a structure, since the central regions on both sides of one end are coated with the insulating adhesive 12, the holding strength is increased. Therefore, even if the other end sways during drop impact, the state change of the conductive adhesive 10 is prevented and the initial state is maintained. As a result, changes in the state of the conductive adhesive 10 on both sides of the one end are reduced, so that changes in the vibration frequency due to the holding system are prevented.

Further, since the state change of the conductive adhesive 10 is reduced, the other end of the crystal piece 2 does not come close to the metal cover 4 after the impact and the stray capacitance increases (electrical system). It also prevents changes in vibration frequency.

Since the insulating adhesive 12 is applied to the central regions on both sides of the one end, the stress generated in the crystal blank 2 is reduced even if heat shrinkage occurs at the time of fixing, and the vibration characteristic including the frequency temperature characteristic is reduced. Prevent deterioration. For example, when applied to both ends of one end, stress (stretching force) acts from both ends in the width direction, but since it is the central region (dotted region), the stress stays within the dotted region and the vibration characteristics deteriorate. To prevent. Moreover, since it is applied to the exposed surface of the crystal piece 2, it is well-known and enhances the adhesive strength.

Further, the conductive adhesive 10 can be used in a small amount as an electrical connection, and the insulating adhesive 12 can provide mechanical strength. In this case, since the amount of the conductive adhesive 10 at both ends is small, the change in state at the time of a drop impact is small, and the stretching force generated between both ends is also reduced to reduce the influence on the vibration characteristics.

In this embodiment, the metal cover 4 may be replaced with an insulating material such as ceramic, which may be sealed with glass or resin. Even in this case, since the state change of the conductive adhesive 10 is reduced, the frequency change caused by the holding system before and after the drop impact is prevented. In this case, since it is an insulating cover, no stray capacitance is generated between it and the crystal piece 2, so that no frequency change occurs even if the other end approaches the insulating cover.

[0021]

[Second Embodiment] Fig. 2 (ab) is a diagram of a crystal resonator for explaining a second embodiment of the present invention. Fig. 2 (a) is a plan view and Fig. 2 (b) is the same figure (a). FIG. The description of the same parts as those in the first embodiment will be omitted or simplified. Previous 1st
In the embodiment, the insulating adhesive 12 is applied to the central region between the conductive adhesives 10 applied on both sides of the one end of the crystal piece 2, but in the second embodiment, the conductive adhesive 10 on both sides of the one end is applied. Mainly for electrical connection only as the lower surface including the side surface of the crystal piece 2. Then, the height dimension is reduced and the distance between the upper surface of the crystal blank 2 and the metal cover 4 is reduced. Insulating adhesive 12
Is applied to the upper and lower surfaces of the crystal piece 2 as a central region on both sides of one end in the same manner as described above for mechanical connection.

With such a structure, as in the first embodiment, since the central regions on both sides of the one end are coated with the insulating adhesive 12, the holding strength is increased. Therefore, even if the other end sways during a drop impact, the state change of the conductive adhesive 10 is reduced and the other end of the crystal blank 2 does not approach the metal cover 4. Prevents changes in vibration frequency due to the system.

Further, in the second embodiment, since the distance between the upper surface of the crystal piece 2 and the metal cover 4 is made small, the other end of the crystal piece 2 is restricted to the metal cover 4 at the time of a drop impact, and the other end of the crystal piece 2 is restricted. Reduce the swing range. Therefore, as compared with the first embodiment, the influence on the conductive adhesive 10 on both sides of the one end is reduced. This further prevents changes in the vibration frequency.

In this case, the conductive adhesive 1 on both ends of one end
Since 0 is only the lower surface including the side surface of the crystal piece 2, an electrical short circuit does not occur even if the distance to the metal cover 4 is reduced.
Then, even if the insulating adhesive 12 applied to the upper surface of the crystal piece 2 comes into contact with the metal cover 4, there is no problem. Since the insulating adhesive 12 is applied to the central regions on both sides of the one end, the influence on the vibration characteristics including the frequency temperature characteristics is small as described above.

Although the insulating adhesive 12 is applied to the upper and lower surfaces of the crystal blank 2 in the second embodiment, it may be applied only to the lower surface including the side surfaces. Further, although the conductive adhesive 10 is only the lower surface including the side surface, it refers to only the lower surface and the side surface, the lower surface, and the side surface, and the point is that the surface is the surface excluding the upper surface.

[0026]

[Other Matters] In the above embodiment, both sides and the central region of one end of the crystal blank 2 are fixed to the bottom surface of the recess of the container body 3. For example, a step is formed on the side wall of the recess to form the other end of the crystal blank 2. May be brought into contact with or brought close to each other to hold both ends of the one end on the step. In this case, for example, as shown in FIG. 3, the crystal oscillator may be configured by accommodating the IC chip 13 in which the oscillation circuit is integrated in the bottom surface of the recess, and the present invention does not exclude this. The mounting electrodes in this case are the power supply, the output,
It becomes earth etc.

[0027]

According to the present invention, the central region of the crystal piece, which is between the conductive adhesives fixed to both ends of the crystal piece from which the extraction electrode is extended, is fixed with an insulating adhesive. Since the cover is a metal cover and the conductive adhesive is applied only to the lower surface including the side surface of the crystal piece, it provides a surface mount resonator with good impact resistance that prevents frequency changes before and after a drop impact. it can.

[Brief description of drawings]

FIG. 1 is a plan view of a crystal unit for explaining a first embodiment of the present invention.

2A and 2B are diagrams illustrating a second embodiment of the present invention, in which FIG. 2A is a plan view and FIG. 2B is a sectional view taken along line AA.

FIG. 3 is a cross-sectional view of a crystal oscillator illustrating another application example of the present invention.

4A and 4B are diagrams of a crystal resonator for explaining a conventional example, in which FIG. 4A is a plan view and FIG. 4B is a sectional view.

[Explanation of symbols]

1 surface mount container, 2 crystal pieces, 3 container body, 4 metal cover, 5 crystal terminals, 6 mounting electrodes, 7 pillows, 8
Excitation electrode, 9 Extraction electrode, 10 Conductive adhesive, 12
Insulating adhesive, 13 IC chip.

Claims (2)

[Claims] 1. A bottom surface of a concave container body is fixed on both sides of one end of a crystal piece from which an extraction electrode extends from an excitation electrode with a conductive adhesive, and an opening surface of the container body is sealed with a cover. In the crystal unit, the central region of the crystal piece, which is between the conductive adhesives that are fixed to both ends of the crystal piece from which the extraction electrode is extended, is fixed with an insulating adhesive. Characteristic crystal unit. 2. The crystal unit according to claim 1, wherein the cover is a metal cover, and the conductive adhesive is applied only to a lower surface including a side surface of the crystal piece.