JPS62247614A - Chip type piezoelectric vibrator - Google Patents

Abstract

PURPOSE:To set a piezoelectric resonator at a proper position and also to prevent a conductive adhesive from flowing into a vibrating part owing to a capillary phenomenon, by forming banks to the inner walls at both ends of a cylindrical insulated case to support a piezoelectric vibrator. CONSTITUTION:As shown in the diagrams, the thick electrodes 14 are formed at both ends of a cylindrical and hollow insulated case 10 so that they enclosed the corners 10a of a cap 12. The thickness of the electride 14 set at such value that prevents a case where a conductive adhesive 22 moves up by a capillary phenomenon produced between the case 10 and a piezoelectric resonator 16. In such a way, the electrodes 14 are formed and the resonator 16 is put into the case 10. Thus both ends of the resonator 16 are supported by those electrodes 14. Then the cap 12 is set. In this case, a space is secured between the surface of the resonator 16 and the inner wall of the hollow part of the case 10. Therefore the adhesive never flows into the vibrating part.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a chip-type piezoelectric resonator, and in particular, a rectangular piezoelectric resonator is arranged in a hollow part of a hollow cylindrical insulating case. The present invention relates to a chip-type piezoelectric vibrator having a structure in which it is fixed in place.

(Conventional technology) This type of chip-type piezoelectric vibrator is already known.

(Problems to be Solved by the Invention) Conventionally, conductive adhesives are used to connect and fix piezoelectric resonators, which makes it difficult to arrange the piezoelectric resonators in an appropriate state within an insulating case. They were often arranged as shown in Figures 6A and 6B.

In the case shown in FIG. 6A, the piezoelectric resonator 2 is completely lowered so as to come into contact with the bottom of the inner wall of the hollow part of the insulating case 1, while in the case shown in FIG. 6B, one end of the piezoelectric resonator 2 It will descend and be placed diagonally. In both cases, the gap between the piezoelectric resonator 2 and the inner wall surface of the insulating case 1 becomes smaller.

Therefore, in this gap, until the conductive paste 4 hardens due to capillarity, the molten conductive paste) 4a
and 4b enter more than necessary. If this happens, the conductive paste I-4a or 4b will adhere to the vibrating part, making it impossible to vibrate properly, and in some cases, causing a short circuit between the conductive base 4a and the electrode 3, or between the conductive paste 4b and the electrode 5. turn into.

Therefore, the main object of the present invention is to provide a chip-type piezoelectric vibrator that is less likely to produce defective products due to capillary action.

(Means for Solving the Problems) Simply put, the present invention includes a cylindrical insulating case and a piezoelectric substrate having an energy-trapping vibrating part, and the piezoelectric resonator is arranged in a hollow part of the insulating case. In a chip-type piezoelectric vibrator, the piezoelectric resonator is provided with a cap that is placed on both ends of an insulating case, and in which the end of the piezoelectric resonator is fixed to the end of the insulating case with a conductive adhesive and is electrically connected to the cap, This is a chip-type piezoelectric vibrator characterized in that a weir made of a conductive material is formed on at least the inner wall of a hollow portion at the end of an insulating case.

(Function) Weirs made of a conductive material such as porcelain are formed at least on the inner walls of the hollow portion at both ends of the hollow cylindrical insulating case.

By appropriately selecting the height of this weir, capillarity between the piezoelectric resonator and the inner wall of the hollow portion of the insulating case due to the conductive adhesive is suppressed.

(Effects of the Invention) According to the present invention, weirs are formed on the inner walls at both ends of the insulating case, and the piezoelectric resonator is supported by the weirs, so the piezoelectric resonator can be easily placed inside the insulating case without using complicated jigs. can be placed at the appropriate location. Furthermore, if the weirs formed on the inner walls at both ends of the insulating case are set to a height that does not cause capillary action between the piezoelectric resonator and the insulating case, the conductive adhesive can be applied to the piezoelectric resonator due to capillary action. It does not extend to the vibrating part. Therefore, according to the present invention, the occurrence of defective products can be reduced as much as possible.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Embodiment) Fig. 1A shows a sectional view of an embodiment of the present invention, and Fig. 1B shows a sectional view of an embodiment of the present invention.
The figure shows an external view. Caps 12 made of a conductive material such as aluminum are press-fitted into both ends of the hollow cylindrical insulating case 10 . The insulating case 10 is made of ceramic such as alumina, for example. Appropriate radiuses are formed at the outer corners 10a of both ends of the cylindrical insulating case 10 so that the cap 12 can be easily press-fitted therein. It is desirable that the curvature of this corner 10a be smaller than the curvature of the inner radius of the cap 12 that is placed thereon. Insulating case 10 for the radius of cap 12
If the radius is larger than the rounded radius, not only will it be easier to press-fit the camp 12, but also the cap 12 and the electrode 14 (Fig. 1A) will be reliably electrically connected on both rounded surfaces, and the continuity of the conduction will be improved. This is because it will be improved.

As shown in FIG. 4, relatively thick electrodes 14 are formed at both ends of the insulating case 10 so as to surround the rounded corners 10a. This electrode 14 is made of a metal such as Ag or Ni, and is formed by baking, for example. In the embodiment, the thickness t (FIG. 4) of the electrode 14 from the inner wall of the hollow part of the insulating case 10 is set to 3.
It was set to 0 μm or more. This t=30 μm is a result obtained through experiments assuming that capillary action, which will be described later, does not occur.

FIG. 2 is an illustrative diagram for explaining the capillary phenomenon of conductive adhesive, and the gap between the insulating case 1 and the piezoelectric resonator 2 is t.
FIG. 3 shows a graph where h is the height of the conductive adhesive 4 rising due to capillary action. This third
As is clear from the figure, when the gap t' becomes 30 μm or less, the height h of the conductive paste 4 rises due to capillary action.
increases rapidly. Therefore, if the thickness t of the electrode 14 formed on the insulating case 10 is set to 30 μm or more, even if the conductive adhesive is filled after the piezoelectric resonator is arranged in a later process, the conductive adhesive will be formed by capillary action. The agent can be effectively prevented from advancing inwardly more than necessary.

The thickness p of the electrode 14 from the outer surface of the insulating case 10 is the first
It is set according to the distance q between the insulating case 10 and the camp 12 shown in Figure A. However, it is better that this thickness p is not too large. This is because if the thickness p is too large, the above-mentioned interval q becomes too large, making the chip shape unfavorable.

Note that in order to reduce the wall thickness p of the electrode 14 on the outside of the insulating case 10, it is effective to round the corners 10a of the insulating case 10 described above. If such a radius is formed, when applying conductive paste for the electrodes 14 to both ends of the insulating case 10 using, for example, a roller, the inner wall of the hollow portion will be thicker (but the outer surface will be thinner).

After forming the electrode 14 shown in FIG. 4, the piezoelectric resonator 16 is then placed in the insulating case IO as shown in FIG. 1A. At this time, both ends of the piezoelectric resonator 16 are supported by the electrodes 14. Note that, like the conventional piezoelectric resonator 16, vibrating electrodes 18 and 20 are formed on the upper and lower surfaces of the piezoelectric resonator 16, partially overlapping each other. Energy trap type vibration occurs in the overlapping portion of the vibrating electrodes 18 and 20.

After placing the piezoelectric resonator 16, caps 12 whose insides are coated with conductive adhesive 22 (FIG. 1A) are fitted to both ends of the insulating case 10, as shown in FIG. 5. At this time, a sufficient gap is maintained between the surface of the piezoelectric resonator 16 and the inner wall of the hollow part of the insulating case IO by the electrode 14, and the conductive adhesive 22 is applied to the piezoelectric resonator 1 by capillary action.
It does not advance to the above-mentioned vibrating part of No.6. That is,
The electrode 14 on the inner wall of the hollow part of the insulating case 10 prevents capillary action of the conductive adhesive 22 and also functions as a dam. In addition, on the inner corner 12a of the cap 12,
As described above, a radius having the same center of curvature as the radius provided at the corner 10a of the insulating case 10 but having a different curvature is provided.

When the press-fitting of the cap 12 is completed, the outer thickness p of the electrode 14 is deformed by the press-fitting, and becomes as shown in FIG. 1A. Then, the insulating case 10 and the cap 12 are completely fixed together. Then, when the conductive adhesive 22 hardens, the piezoelectric resonator 16 is fixedly held within the insulating case 10. At the same time, the electrodes 18 and 20 of the piezoelectric resonator 16 are fully electrically connected to the cap 12 via the conductive adhesive 22, respectively.

[Brief explanation of drawings]

FIG. 1A is a sectional view showing an embodiment of the present invention. FIG. 1B is an external perspective view of this embodiment. FIG. 2 is an illustrative diagram for explaining capillary phenomenon. FIG. 3 is a graph showing the relationship between the gap and the advancement height in capillary action. FIG. 4 is an illustrative cross-sectional view showing a state in which electrodes are formed at both ends of the insulating case. FIG. 5 is an illustrative cross-sectional view for explaining a state in which a cap is press-fitted into an insulating case in which electrodes are formed. FIGS. 6A and 6B show cross-sectional views of a conventional chip-type piezoelectric vibrator. In the figure, 1o is an insulating case, 16 is a piezoelectric resonator, 2
2 is a conductive paste, 12 is a cap, and 14 is an electrode. Patent applicant Murata Manufacturing Co., Ltd. Agent Patent attorney Yama 1) Yoshito (and 1 other person) Figure 1A Figure 118 Figure 2 Figure 3 Figure 4 Figure 5 Figure 116A j 4D

Claims (1)

[Claims] It includes a cylindrical insulating case, a piezoelectric substrate having an energy trap type vibrating part, a piezoelectric resonator disposed in a hollow part of the insulating case, and a cap placed on both ends of the insulating case, and a conductive In a chip-type piezoelectric vibrator in which an end of the piezoelectric resonator is fixed to an end of the insulating case with an adhesive and electrically connected to the cap, at least the inner wall of the hollow portion at the end of the insulating case is conductive. It is characterized by having a weir made of a flexible material.
Chip type piezoelectric vibrator.