JPS5899021A - Piezoelectric resonance component - Google Patents

Abstract

PURPOSE:To obtain the case construction hoving excellent sealing effects, by providing a projection for the positioning of internal elements to one major plane of a base of a piezoelectric resonance component and mounting the internal elements to the base from the upper side of the projection. CONSTITUTION:In a base 14 of a piezoelectric resonance component, walls 20, 20 are provided from both long sides of a rectangular plate 19, and walls 21, 21 are provided at the one end of the plate 19. A pair of pillar projections 22, 22 and four pillar projections (as one set) are provided at the inside surrounded with the walls 20, 21. A rubber sheet 16 is mounted to a part surrounded with the projections 23 from the upper side. A piezoelectric resonance element 1 is guided with the projections 22, 23 an mounted from the upper side. An input/output terminal board 15 is inserted to the clearance between the walls 20 and 21, and between the projections. A lead part of an earth terminal board 17 is inserted to a recess 201 at the middle of the lower side wall 20. The opening of a case 18 is sealed with a resin 35, and since the wall chokes most part of the opening 32, sealing can be done surely and excessive resins can not be infilterated to the inside.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to piezoelectric resonant components such as piezoelectric filters.

For example, the center frequency of a piezoelectric filter for an AM receiver is several hundred kiloliters, for example 450 kilohertz,
From various viewpoints such as mass productivity, there are the following three types of filter structures. The first is a Yurmann-shaped filter. This filter requires an IFT, and has drawbacks such as: 1) It is difficult to match the IFT and the piezoelectric resonator, 2) The reliability of the coil is low, 2) It is large, and 2) It is expensive.

The second type is a three-terminal filter that uses the spreading vibration mode of a square plate and the radial vibration mode of a disc. This filter is: ■ Relatively large, especially when using a disk with a third-order high wave, the size is the same. ■ When using a square plate, spurious vibrations due to circular vibration mode are strongly excited. be done,
There are drawbacks such as. The third type is a filter that utilizes dual modes of longitudinal vibration of a rectangular plate. This filter is: ■Difficult to adjust the two resonators, ■Complicated structure,■
It has disadvantages such as being expensive.

This invention has various features. The present invention relates to a method of manufacturing a piezoelectric resonant component having a structure completely different from that of the conventional structure, and has the following objectives.

An object of this invention is to provide an inexpensive piezoelectric resonant component.

Another object of the present invention is to provide a piezoelectric resonant component in which the variation in characteristics between products is small by 4°.

Another object of the present invention is to provide a piezoelectric resonant component with excellent manufacturing efficiency.

Another object of the present invention is to provide a piezoelectric resonant component having a case structure with excellent sealing effect.

Another object of the invention is to provide a piezoelectric resonant component having a structure that allows automatic assembly.

Another object of the invention is to provide a piezoelectric resonant component having a structure that is easy to assemble.

That is, the gist of the present invention is to provide a piezoelectric resonant component in which at least a part of an internal element is mounted on a substantially plate-shaped base, the base is housed in a case from the mouth of the case, and the opening is sealed with resin. The base has a protrusion for positioning the internal element on one of the main planes of the base so that the internal element can be attached to the base from above the protrusion, and the base has a wall portion that blocks the opening of the case. It is a piezoelectric resonant component characterized by having:

Embodiments of the invention will be described below with reference to the drawings.

Figure 1 shows the components of a piezoelectric resonant component, piezoelectric resonant element 1.
shows. In the figure, 2 is a piezoelectric ceramic substrate, and a groove 3 along the length β direction is provided on the surface of the substrate 2, and one main surface is divided into two equal parts in the length β direction by the groove 3. Further, grooves 4 and 5 are formed in the direction intersecting the length Q direction, each being 1/3 from the center of the length β direction! It is installed in the position of Therefore, on one main surface of the substrate 2, an input electrode 6,
An output electrode 7 and independent electrodes 8 to 11 are provided separated by grooves 3 to 5. Furthermore, a full-surface electrode 12 is provided on the other main surface of the substrate 2 . Then, we will use a length vibration mode that expands and contracts in the length direction, and the dimensions of each part of the board 2 are, for example, when the center frequency is 450k)lz, the length is about 4.0511IIG and the width is 0.611
111, thickness is 0.3111R1, depth of groove 3 is 0.
151+1 wire, the width of groove 3 is 0.1511, and the depth and width of groove 4.5 may be arbitrary as they are only for electrically separating electrode 6.7 from electrode 8 or 9.10 or 11. . FIG. 2 shows an electrical symbol of the piezoelectric resonant element 1 shown in FIG. In this way, the piezoelectric resonant element 1 shown in FIG. 1 can be used as a filter element using single mode vibration in the longitudinal direction.

A method of manufacturing this piezoelectric resonant element 1 will be explained below. - Rectangular plate-shaped ceramic sintered body 101 with sides on the order of several cm
Prepare the surface by wrapping. Electrodes are provided on the opposing main surfaces. This electrode is an electrode for polarization processing, and also serves as electrodes 6 to 12. As shown in FIG. 3, the ceramic sintered body 101 imparted with piezoelectricity by polarization treatment is assembled into a large number of piezoelectric resonant elements 1 of a predetermined size using a dicing saw 13 in order to increase manufacturing efficiency.
At the same time as cutting out, form 3-5. That is,
According to dicing saw 13, the cutting accuracy is ±2μm.
Since the piezoelectric resonant element 1 can be cut out with an accurate length 2, steps such as frequency selection and frequency adjustment can be omitted compared to conventional manufacturing methods. For example, when we wanted to obtain one with a center frequency of 455 kHz, the variation in center frequency was kept within a maximum of 1.2 kHz. Further, by forming 1II3 to 5, the input electrode 6 and the output electrode 7 having the necessary external dimensions can be obtained by reusing the polarized electrodes. In this regard, in the conventional manufacturing method, after polarization, a pattern of vibrating electrodes is printed on the polarized electrode with resist ink.
It can be said that the present invention is obviously simpler since it involves a process such as etching. 4.5 is input electrode 6
, the squareness in the length β direction of the output electrode 7 is reduced to 2/3, and has the effect of suppressing the third harmonic. Therefore, electrodes 8 to 11 are idle. The dicing saw 13 has a blade that rotates at high speed and moves in the six directions of the arrows in FIG. 4, and although it cannot cut deeply, it is sufficiently useful for cutting the thickness of the piezoelectric plate targeted by the present invention.

Further, by moving the dicing saw 13 in the eight directions indicated by the arrows in FIG. 4 and setting appropriate values, it is possible to perform cutting and to form grooves of arbitrary depth. Therefore, one method for cutting or forming grooves is to temporarily fix a plurality of piezoelectric elements 1 together and form grooves or cutting them in the horizontal direction in the figure, as shown in FIG. However, it is more efficient to form and cut the grooves in the downward direction of F in the figure.

5 to 7 show the base 14, and the base 14 includes an input/output terminal plate 15, a conductive rubber sheet 16, which will be described later.
The piezoelectric resonant element 1 and the ground terminal plate 17 are mounted with their mutual positional relationship regulated. As will be described later, when inserting these internal elements into the case 18, the ground terminal plate 17 is designed to have an appropriate contact pressure with the piezoelectric resonant element 1 by adjusting the shape and dimensions of the ground terminal plate 17 relative to the inner wall surface of the case 18. I'm trying to get it. The base 14 has the following structure. @20,2 from both long sides of the rectangular plate-shaped part 19
0 is provided integrally with the portion 19, and the low l is provided from both short sides.
21, 21 are provided integrally. In addition, these walls 20,
20, 21. Inside surrounded by 21, there is a pair of columnar bodies 2.
2, 22, and a set of four columnar bodies 23, 23.2323 are provided integrally with the portion 19, respectively. Then, the input/output terminal board 15 is symbolically shown by the dashed line in the figure. do.

As shown more clearly in FIG. 8, the input/output terminal board 15 is
Between the right end of the wall 20 having the input terminal portion 24 and the output terminal portion 25 and the lower end of the right low 121, between the right column 22 and the right low 121, and between the upper wall 20 and the upper right column. 2
3, and the upper left columnar body 23 and the upper right columnar body 23
It is fitted into each gap between the

The output terminal portion 25 is located on the left side of the low wall 21 in FIG.
Between the lower end of and the left end of the lower 1120, the lower left columnar body 2
3 and the lower wall 20, and between the lower left columnar body 23 and the lower right columnar body 23. As is clear from the figure, tapers are provided at all locations to facilitate fitting.

Next, in FIG. 5, four columnar bodies 23, 23°2
A conductive rubber sheet 16 as shown in FIG. 9 is placed in the area surrounded by 3.23. Further, the piezoelectric resonant element 1 is placed on the rubber sheet 16 with the third to fifth sides facing down.

The piezoelectric resonant element 1 is restrained by a pair of columnar bodies 22 and four columnar bodies 23 of the base 14. Then, the tips 26 and 27 of the input terminal portion 24 and output terminal portion 25 of the input/output terminal plate 15 come into contact with the input electrode 6 and output electrode 7 of the piezoelectric resonant element 1 via the conductive rubber sheet 16. It is. This rubber sheet 16 is called an anisotropically conductive rubber sheet, and is composed of, for example, graphite fibers or thin metal lines embedded in the thickness direction of a silicone rubber sheet. It exhibits conductivity in the thickness direction and insulation in the lateral direction. Therefore, the piezoelectric resonant element
The input electrode 6 and the output electrode 7 of 1 come into contact with the tip 26 of the input terminal portion 24 and the tip 27 of the output terminal portion 25 via the anisotropically conductive rubber sheet 16, respectively, without mutual short circuit.

The ground terminal plate 17 is shown more clearly in FIGS. 10-12. The ground terminal plate 17 has a substantially H-shaped tip 29 integrally formed with a lead portion 28, and has a contact protrusion 291 at the center. The tip 81129 is arcuately shaped to provide necessary elasticity, as shown in FIGS. 10 and 12. Further, a portion of the lead portion 28 that is accommodated in the case 18 has a bent portion 30 in a substantially crank shape. Depending on the bending condition, the tip portion 29 and the lead portion 28 are not parallel, but their extension lines intersect (for example, at an intersection angle of θ-10°).

The shape of the case 18 is shown more clearly in FIGS. 13-15. As shown in the figure, an opening 32 is formed on the bottom surface of the approximately box-shaped molded body having a taper 31 to improve the directionality, that is, the surface where the input/output terminal board 15 and the ground terminal board 17 are guided. has. The inner space 33 has a convex cross-section expanding toward the back to resemble the outer shape of the base 14. The edge of the opening 32 has a taper 34 to facilitate insertion of the internal element.

FIG. 16 shows the base 1 in relation to this invention.
4, the human/output terminal board 15, the rubber sheet 16, and the piezoelectric resonant element 1 are stacked, and the jJ-de frame of the ground terminal board 17 is stacked on the lead frame connection part of the input/output terminal board 15, and the ground terminal This figure shows the state before the plate 17 is pressed into contact with the contact protrusion 291 on the entire surface of the piezoelectric resonator 1 at the center of the electrode 12 before being inserted into the case 18. As shown in the figure, when the internal elements assembled into the case 18 are viewed from the side, the ground terminal plate 17 has a wedge-like shape due to its T5 shape. When the internal element is inserted into the case 18 in this state, the end portion 29 and the bent portion 30 of the ground terminal plate 17 are pressed against the inner wall surface of the case 18, and the reaction force causes the ground terminal plate 11 to remain in contact with the ground terminal plate 11 even from the beginning to the end of insertion. base 14
the piezoelectric resonant element 1, the conductive rubber sheet 16,
Appropriate pressure is applied to the input/output terminal plate 15, and after the insertion is completed, piezoelectric Since the contact pressure necessary to hold the resonant element 1 is obtained, the case 18 is removed without any misalignment of each component.
contained within.

Note that FIGS. 17 to 19 show the state of the finished product. The lead portion 28 of the ground terminal plate 17 is located in the recess 2 in the center of the lower wall 20 of the base 14 in FIG.
I'm hooked on 01.

The opening 32 of the case 18 is made of a general sealing resin 35.
sealed by. At this time, since the lower wall 20 of the base 14 in FIG. 5 covers most of the opening 32, the sealing is ensured and the size is reduced by preventing excess resin from going around inside. It is natural that small culms are made reliably. However, the smaller the opening, the more difficult it becomes to insert internal components through the opening of the case. As described above, in the present invention, the entire internal parts are assembled into a crib shape before being inserted, so even if the opening is small, insertion is easy and assembly by machine is possible, which makes automatic assembly possible. This has the synergistic effect of being easy to assemble and ensuring reliable sealing.

FIG. 20 shows a selection characteristic curve of a filter using one piezoelectric resonant element according to the present invention. FIG. 21 shows the selection characteristic curve of a device in which one IFT is further connected in cascade. FIG. 22 shows a selection characteristic curve of two piezoelectric resonant elements according to the present invention directly connected in cascade without using a coupling capacitor. FIG. 23 shows the selection characteristic curve of a device in which one IFT is further connected in cascade. FIG. 24 shows spurious characteristics of a filter in which two piezoelectric resonant elements and an IFT-piece are connected in cascade according to the present invention.

As is clear from the above description, in the present invention, at least a part of an internal element is attached to a substantially plate-shaped base, and this base is accommodated in a case through a narrow opening on the case surface, and the opening is closed. In a piezoelectric resonant component that is sealed with resin, one of the principal planes of the base has a convex portion for positioning the internal element so that the internal element can be attached to the base from above the convex portion, and the opening of the case Since this is a piezoelectric resonant component characterized in that the base has a wall portion that extends over the isl portion, it has the following effects.

According to this invention, since the elements and the like are housed in the case from the side of the case, that is, the side from which the bow 1 lead is pulled out, the sealing period is short and the sealing period is easily damaged. However, since there is a wall part that prevents the resin from entering the internal base, the resin will not get around to the inside.

Note that it goes without saying that the present invention can be applied even if the type of piezoelectric resonant element, the holding structure of the piezoelectric resonant element, etc. are different from those of the above-described embodiments.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a piezoelectric resonant element, FIG. 2 is an electrical symbol diagram of the one shown in FIG. 1, FIG. 3 is a front view of a plurality of ceramic sintered bodies, and FIG. FIG. 5 is a front view of the base, FIG. 6 is a cutaway view from the bottom, FIG. 7 is a cutaway view from the side, and FIG. A front view of the input/output terminal board, FIG. 9 is a front view of rubber seams 1 to 1, FIG. 10 is a top view of the ground terminal board, FIG. 11 is a front view of the same, and FIG. 12 is a += +
, a side view, FIG. 13 is a side view of the case, and FIG. 14 is a side view of the case.
15 is a bottom view, FIG. 16 is an exploded sectional view of the piezoelectric resonant component according to the present invention, and FIG. 17 is a front view, and FIG. Figure 19 is a broken view seen from the bottom, Figures 20 to 23 are selection characteristic curve diagrams, and Figure 24 is a spurious characteristic curve diagram. 1...Piezoelectric resonant element , 2...Piezoelectric ceramic substrate, 3 to 55...groove, 6...
・Input electrode, 7...Output electrode, 8-11...
...Independent electrode, 12...Full surface electrode, 13...
...Dancing Saw, 14...Base, 1
5... Input/output terminal board, 1G... Conductive rubber sheet, 17... Earth terminal board, 18.
...Case, 19...Rectangular plate-shaped part,
20...Wall, 21...Low wall, 22...
... Column, 23... Column, 24...
...Input terminal part, 25...Output terminal part,
26...Tip, 27...Tip, 28.
...Lead part, 29...Tip part, 30
...Bending part, 31...Taper,
32...Opening, 33...Inner space, 3
4...Taper, 35...Sealing resin, 101...Ceramic sintered body, 291...
...Contact protrusion. Patent application Murata Manufacturing Co., Ltd.M1 Figure ZFigure M1O figure

Claims (1)

[Claims] In a piezoelectric resonant component in which at least a part of the internal element is mounted on a substantially plate-shaped base, this base is housed in the case 4 through a narrow opening on the case surface, and the opening is sealed with resin. One side has a convex part for positioning the internal element so that the internal element can be attached to the base from above the convex part, and the base has a wall part that blocks the opening of the case. Piezoelectric resonant components.