JPH02174413A - Thin profile piezoelectric vibrator - Google Patents

Abstract

PURPOSE:To make the profile of a vibrator thin and to improve the vibration- proof and shock resistance by supporting a piezoelectric substance with one end of a thin metallic plate of nearly a rectangular shape from both sides. CONSTITUTION:A connection electrode 11b of a piezoelectric substance 11 is connected electrically to one end 12d of a lead plate 12 formed to be of a rectangular shape to provide a buffer effect with a conductive adhesives or the like. Then the plate 12 is clipped from both sides with a rectangular shaped sheet 14 made of a material such as glass fiber, clipped with the circumferential part of a metallic thin plate shell 13 having a recessed part 13a in the middle from both upper and lower faces, adhered and sealed air-tightly. The width of the plate 12 and the shell 13 is made equal and the plate thickness of the plate 12 at the outside of the shell 11 is made thicker than that of the other part, the alignment at assembling is facilitated. Thus, the vibration-proof and shock resistance of a thin piezoelectric vibrator usable for a card type electronic device is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention allows the overall thickness to be significantly reduced,
Vibration resistance, resistance? The present invention relates to a thin piezoelectric vibrator with good gj impact characteristics.

(Technical background of the invention and its problems) In general, piezoelectric vibrators are used in large quantities in the wide field of electronic technology, and in particular, crystal vibrators using crystal pieces as piezoelectric bodies have high frequency stability. It is widely used as a time and frequency reference source for communication equipment, digital control equipment, etc.

In particular, the demand for piezoelectric vibrators has increased in recent years as electronic devices have become smaller and more sophisticated, and their price and size have been rapidly reduced.Also, with advances in surface mounting technology, they have become thinner and can be mounted on surfaces. A piezoelectric vibrator is desired.

For this reason, piezoelectric vibrators have been put into practical use, for example, in which a crystal piece is held on a plate-shaped base made of ceramic or the like, and a cover is placed over the crystal piece.

FIG. 8 is a side sectional view showing an example of such a piezoelectric vibrator, in which a metal holding piece 2 is fixed to a plate-shaped base l made of ceramic, and both ends of a crystal piece 3 are attached to this holding piece 2. hold.

Then, the crystal piece 3 is attached to the plate surface of the base 1 through a conductive pattern 4 formed by, for example, metallization processing.
The electrode formed on the surface is led out. A box-shaped ceramic lid 5 with an open bottom is placed over the base 1 to airtightly seal it.

In this way, the heat resistance of the ceramic used for the base 1 and the lid 5 is good, and the base 1 and the lid 5 are
If they are made of the same material, they have the same coefficient of thermal expansion, and even if they are heated for soldering when mounted on a printed circuit board, no damage such as cracks or chips will occur, and reliability can be improved.

However, as shown in FIG. 8, the container made of ceramic cannot be made very thin, so it cannot be used for card-type electronic equipment with a thickness of about 1 mm.

For this purpose, Utility Application No. 1983 filed by the same applicant as the present invention.
-161494, patent application No. 63-4348,
It has been considered that electrodes are led out from both ends of a piezoelectric body and connected to a thin plate-like lead plate, and the lead plate is sandwiched from both sides of the plate surface via a sheet impregnated with an adhesive.

By the way, in this type of device, the lead plate is held at the longitudinal end of the piezoelectric body by extending parallel to the longitudinal direction. Therefore, if an external shock is applied, the lead plate itself has little cushioning effect and the piezoelectric body There was a problem that it was easy to cause damage.

For this reason, when an IC card was assumed to be used as the application for such a crystal resonator, a drop test was performed by mounting the crystal resonator on a 30 g (Durham) board, and it was found that there was a problem with reliability.

(Object of the invention) The present invention has been made in view of the above circumstances, and has vibration resistance,
The object of the present invention is to provide a thin piezoelectric vibrator that can significantly improve impact resistance.

(Summary of the Invention) The present invention provides a holding part that bridges the ends of arm parts protruding in parallel from a base part with a bridge part, and holds a longitudinal end of a rectangular piezoelectric body in the center part of the bridge part. A pair of lead plates made of thin metal plates formed with a The piezoelectric body is hermetically sealed by sandwiching the lead plate.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 5.

FIG. 1 is an assembled perspective view, and reference numeral 11 in the figure shows, for example, a quartz crystal cut at a predetermined angle, formed into a rectangular plate shape, and provided with electrodes 11a on both sides of the plate. This is a piezoelectric body led out to the connection electrodes 11b at both ends of the .

Both ends of the piezoelectric body 11 are fixed to the lead plate 12 with a conductive adhesive or the like to mechanically hold them, and the connection electrode 11b is electrically connected to the lead plate 12. The lead plate 12 is made of a thin metal plate, such as nickel silver, and is formed into a roughly square shape.

That is, FIG. 2 is a plan view showing the lead plate 12, and FIG. 3 is a side view, in which arm portions 12b protrude in parallel from both sides of the base portion 12a, and a bridge portion 12c bridges the tips of the arm portions 12b. At the same time, a holding portion 12 is provided at the center of this bridging portion 12C.
d.

Then, as shown in the perspective view of FIG.
2 are arranged facing each other, and the ends of the rectangular piezoelectric body 11 in the longitudinal direction are held by the holding portion 12d. The surface of the lead plate 12 is roughened by, for example, being lightly etched on the entire surface in order to improve its adhesion to adhesives.

A pair of rectangular shells 13 are provided on both sides of the lead plate 12, facing each other. This shell 13 is made of a thin metal plate such as 5US304, for example,
The width dimension is the same as that of the lead plate, and a recess 13a is formed in the center of the opposing surface.

Then, as shown in the sectional view shown in FIG.
Seats 14 are interposed between both side plate surfaces of the shell 13 and each shell 13. This sheet 14 is located in the recess 1 of the shell 13.
3a, a through hole 14a is formed in the center thereof, and the sheet is made of, for example, glass fiber, and is impregnated with an adhesive.
Then, the lead plate 12 is sandwiched and bonded from both sides at the peripheral edge of the shell 13 via this sheet 14 to airtightly seal it. The sheet 14 impregnated with adhesive in this manner is non-conductive, and serves to fix the peripheral edge of the shell 13 and the lead plate 12 and to electrically insulate them.

Since the external width dimensions of the shell 13 and the lead plate 12 are made equal, positioning can be easily performed by aligning the edges of both in the width direction.

Further, in the above embodiment, as shown in the side view of the lead plate 12 shown in FIG.
The lead plate 12 located outside the shell 13 compared to l.
The plate thickness t2 is increased. Therefore, the lead plate 12 can be easily positioned in the longitudinal direction of the shell 13, which has the advantage of improving productivity.

Note that the width of the lead plate 1 is smaller than the width of the recess 13a of the shell 13.
If the width of the part located inside the recess in No. 2 is widened,
The adhesive exuding from the sheets 14 on both sides of the lead plate 12 directly solidifies with each other, and a sealing effect is also obtained by the adhesive.

In this way, for example, the thickness of the lead plate 12 and the sheet 14 can be set to 0.05 mm, and the thickness of the shell 13 can be set to 0.05 mm.
．． It is possible to reduce the thickness to about 5 mrn, and the overall thickness after assembly can be made as thin as about 1 mm.

Therefore, it can be used for card-type electronic devices, etc.
It is possible to provide a piezoelectric vibrator that is easy to assemble and is inexpensive.

FIG. 6 compares the results of a drop test between the piezoelectric vibrator according to the above embodiment and the piezoelectric vibrator in which the piezoelectric body 11 is held by a lead plate 15 having no bridging portion as shown in the perspective view of FIG. This is a graph shown as follows.

The size of the sample shell 13 is 11. 0mmX5.
0, the size of the piezoelectric body 11 is 8. 0mmX2. Om
The m common imaging frequency is 8.64MH2.

The solid line in the figure indicates the amount of frequency shift and the range of variation in shift after the drop test of the piezoelectric vibrator according to the above example,
The broken line indicates the amount of frequency shift and the range of variation in frequency when a piezoelectric vibrator having a holding structure as shown in FIG. 7 is subjected to a drop test.

Note that one drop in each of the three orthogonal axes X, Y, and Z is one cycle.

During this drop test, the holding structure shown in Figure 7 was
Of the 0, 1 stopped oscillating after 30 cycles, and 3 stopped oscillating after 50 cycles, but none of the above examples stopped oscillating even after 50 cycles of the drop test.

As is clear from the above results, in the above examples, the amount of frequency shift was small and there was no damage, and extremely good vibration resistance and impact resistance were obtained.

Note that the present invention is not limited to the above embodiments,
For example, the shell 13 may be made of glass, ceramic, etc., and it goes without saying that these surfaces may be coated with metal to provide shielding.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to significantly reduce the thickness of the piezoelectric vibration device, which can be used in card-type electronic equipment, and which has good vibration resistance and impact resistance. Child can be provided.

[Brief explanation of the drawing]

Fig. 1 is an assembled perspective view showing one embodiment of the present invention. Fig. 2 is a plan view of the lead plate of the above embodiment. Fig. 3 is a side view of the lead plate of the above embodiment. Fig. 4 is a lead plate. Figure 5 is a side cross-sectional view of the assembled state, Figure 6 is a graph showing the results of a drop test, and Figure 7 is an example of a previously considered holding structure. FIG. 8 is a side sectional view showing an example of a conventional thin vibrator. 11...Piezoelectric body 12...Lead plate 12c...Bridging portion 12d...Holding portion 13◆φ@Medium shell 14・φ...Seat drop cycle times 11 momme

Claims (1)

[Scope of Claims] A rectangular piezoelectric body with electrodes formed on both side plate surfaces and led out to both ends in the longitudinal direction, and an arm protruding in parallel from the base to bridge the ends of the arms. a pair of lead plates made of thin metal plates arranged opposite to each other, forming a holding part for holding the longitudinal ends of the piezoelectric body in the center of the bridging part; A pair of rectangular shells having a width equal to the lead plate and having a recess in the center thereof and sandwiching the lead plate from both sides of the plate, and a pair of rectangular shells having a width equal to that of the lead plate; What is claimed is: 1. A thin piezoelectric vibrator comprising: a sheet interposed between the inner and outer walls and having a through hole formed in the center corresponding to the recess.