JPH0749860Y2 - Chip type piezoelectric resonator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a sealing structure for a chip-type piezoelectric resonator.

[Conventional technology]

Conventionally, as this type of chip-type piezoelectric resonator, for example, one disclosed in Japanese Utility Model Laid-Open No. 61-136630 is known. This piezoelectric resonator is one in which an adhesive is applied to both sides of a piezoelectric substrate having an energy trap type thickness longitudinal vibration mode structure, and is sandwiched between two insulating substrates from the outside. A vibrating space is formed around the vibrating electrode, and the terminal electrode of the piezoelectric substrate and the external connection electrode formed on the outer surface of the insulating substrate are electrically connected by the conductive film formed on the end surface.

[Problems to be solved by the device]

The interval between the piezoelectric resonators makes it difficult to obtain a reliable sealing property of the vibration space formed around the vibration electrode of the piezoelectric substrate. That is, in the above case, the adhesive also serves as the spacer, and the vibrating space is obtained only by the thickness of the adhesive. Therefore, when the insulating substrates on both sides are strongly pressed, the adhesive is crushed and the vibrating electrode is formed. There is a risk of contact with the insulating substrate. Therefore, the pressure applied to the insulating substrate cannot be increased so much, and the sealing performance becomes insufficient.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a chip type piezoelectric resonator capable of enhancing the sealing property of a vibration space by sufficiently applying a pressure to an insulating substrate.

[Means for Solving the Problems]

To achieve the above object, the present invention comprises a piezoelectric substrate and two insulating substrates having substantially the same shape as the piezoelectric substrate and sandwiching the piezoelectric substrate from both sides. Opposing vibrating electrodes are formed, and terminal electrodes respectively connected to the vibrating electrodes are formed at opposite ends of both main surfaces, and the inner surface of the insulating substrate facing the main surface of the piezoelectric substrate is formed. Has a first concave portion at a portion corresponding to the vibrating electrode and a second concave portion opening at a side end surface of the insulating substrate at a portion corresponding to the terminal electrode, and both ends of an outer surface not facing the main surface. An external connection electrode is formed in the portion, and a portion of the surface opposite to the piezoelectric substrate and the insulating substrate, other than the first and second recesses, is bonded and fixed via an adhesive,
The terminal electrode of the piezoelectric substrate and the external connection electrode of the insulating substrate are
It is characterized in that the second recess is electrically connected by a conductive film continuously formed on the side end surface of the opening and the inner surface of the second recess.

[Action]

That is, when the insulating substrate is pressure-bonded to both sides of the piezoelectric substrate via the adhesive, the portions other than the first and second recesses of the insulating substrate are pressure-bonded to the piezoelectric substrate, and the vibration space is formed around the vibrating electrode by the first recess. Is formed. At this time, the vibrating space does not depend on the thickness of the adhesive and is given by the depth of the first recess. Therefore, even if the pressure of the insulating substrate is increased, the insulating substrate does not come into contact with the vibrating electrode. Therefore, it is possible to obtain a high sealing property of the vibration space.

In addition, by continuously forming a conductive film on the inner surface and the side end surface of the second recess of the insulating substrate, the terminal electrodes of the piezoelectric substrate and the external connection electrodes of the insulating substrate are electrically connected, and the chip type A piezoelectric resonator can be obtained.

〔Example〕

1 and 2 show a chip type piezoelectric resonator 1 according to the present invention.
An example of this is shown in FIG.
It has a structure in which it is sandwiched between a plurality of insulating substrates 10, 10.

In the drawing, the piezoelectric substrate 2 is made of a rectangular thin plate ceramic or the like, and electrodes 3 and 4 symmetrical to each other are formed on both front and back main surfaces as shown in FIG. It has a structure. The electrode 3 on the front main surface is a circular vibrating electrode 3a located in the center of the substrate 2,
A terminal electrode 3b formed on one end of the substrate 2 and a vibrating electrode
3a and two lead electrodes 3c connecting the terminal electrode 3b, and the electrode 4 on the back side is also the vibrating electrode 4a and the terminal electrode 4b.
And the extraction electrode 4c. The vibrating electrodes 3a, 4
By providing two lead electrodes 3c and 4c each connecting a and the terminal electrodes 3b and 4b, disconnection of the lead electrodes 3c and 4c can be prevented. Further, since the electrodes 3 and 4 have the same shape and are formed at 180 ° symmetrical positions on the front and back surfaces of the substrate 2, there is no directionality and the assembly by an automatic machine is easy.

The upper and lower insulating substrates 10 and 10 are insulating plates having the same shape as the piezoelectric substrate 2, and are made of a known material such as glass epoxy resin or ceramic material. As shown in FIG. 4, a vibrating electrode is provided at the center of the inner surface facing the piezoelectric substrate 2.
A circular first concave portion 11 larger than 3a, 4a is formed, and a semicircular second concave portion 12, which partially corresponds to the terminal electrodes 3b, 4b, is formed at both ends.
12 are formed. The second recesses 12, 12 are open on the side end surfaces of the insulating substrates 10, 10. Strip-shaped external connection electrodes 13 and 13 are formed over the entire width at both ends on the outer surface opposite to the surface where the recesses 11 and 12 are formed and corresponding to the back side of the second recess 12. .

The adhesive 20 is made of a thin insulating adhesive sheet as shown in FIG. 5, and has holes 2 at positions corresponding to the recesses 11 and 12 of the insulating substrate 10.
1 and a notch 22 are provided. In order to improve mass productivity, it is preferable that the adhesive 20 is printed on the upper and lower insulating substrates 10, 10 by a squeegee printing method. The piezoelectric substrate 2 and the insulating substrates 10 and 10 are bonded to each other with the adhesive 20 in between.
The sealed vibration spaces 5 and 6 are formed between and the insulating substrates 10 and 10. As shown in FIG. 2, conductive films 7 and 7 are sputtered on the side end faces on which the external connection electrodes 13 and 13 are formed so as to be continuous with the inner surface of the second recess 12. , 7 electrically connect the terminal electrodes 3b, 4b of the piezoelectric substrate 2 and the external connection electrodes 13, 13 to each other.

Here, a specific method for manufacturing the chip-type piezoelectric resonator 1 having the above configuration will be described.

First, as shown in FIG. 6, a piezoelectric substrate base material 2A having a large number of electrodes 3 and 4 formed thereon, and an insulating substrate having a large number of recesses 11 and 12 formed on one surface thereof and an external connection electrode 13 formed on the other surface thereof. Base material 10A,
Then, the adhesive sheet base material 20A having a large number of holes 21 and 22 is laminated on each other, and the insulating substrate base material 10A is pressed to produce the resonator base material 1A as shown in FIG. In this state, between the piezoelectric substrate base material 2A and the insulating substrate base material 10A, a large number of vibration spaces due to the concave portions 11 and a large number of spaces due to the concave portions 12 are formed. In order to improve mass productivity, an adhesive layer may be previously formed on the insulating substrate base materials 10A, 10A by a squeegee printing method instead of the adhesive sheet base material 20A. After that, when the resonator base material 1A is cut as shown by the broken line in FIG. 7,
A large number of chip type piezoelectric resonators 1 as shown in FIG. 1 are obtained. At this time, the vibration space defined by the first recess 11 is not exposed to the outside in a sealed state, but the space defined by the second recess 12 is cut in half, so that the terminal electrodes 3b and 4b of the piezoelectric substrate 2 are exposed to the outside. In this state, when the conductive film 7,7 is sputtered on the end face of the side portion on which the external connection electrodes 13,13 are formed,
A part of the conductive film 7 is also formed on the inner surface of the second recess 12, and the terminal electrodes 3b and 4b and the external connection electrodes 13 and 13 are electrically connected through the conductive film 7. After the conductive films 7 and 7 are sputtered as described above, Ni + Sn plating or solder Dip is applied to the outer surface.
By performing the processing, the chip type piezoelectric resonator 1 is completed.

In the piezoelectric resonator 1, the vibrating spaces 5 and 6 are the insulating substrate 10 and
Since it is formed by the first concave portion 11 of 10, there is no need to increase or decrease the pressure applied to the insulating substrate 10 unlike the conventional one in which the vibration space is formed by the thickness of the adhesive, and a large pressure is applied. You can Therefore, the adhesive 20
Between the piezoelectric substrate 2 and the insulating substrate 10 or the adhesive 20
Since there are no air holes inside, the sealing performance of the vibrating spaces 5, 6 is significantly improved. Further, since the adhesive 20 only needs to have a function of sealing, it can be configured by a thin adhesive sheet. As a result, the compression margin at the time of pressurization can be reduced, the air accumulated in the vibrating space is hardly compressed, and it is possible to prevent the generation of air leak holes due to the compressed air leaking to the outside.

Further, when the chip-type piezoelectric resonator 1 is manufactured from the base materials 2A and 10A as shown in FIG. 6, a large number of first recesses 11 and second recesses 12 can be simultaneously press-formed on one surface of the insulating substrate base material 10A. Therefore, the positional relationship between the recesses 11 and 12 can be set in advance with high precision by the press die. Therefore, the final piezoelectric resonator 1
In this stage, the positional relationship between the concave portion 11 for forming the vibration space and the concave portion 12 for external connection is small, and the high quality chip type piezoelectric resonator 1 can be obtained.

It is needless to say that the present invention is not limited to the piezoelectric resonator using the thickness extensional vibration mode.

[Effect of device]

As is apparent from the above description, according to the present invention, the vibrating space is formed around the vibrating electrode by the first recess of the insulating substrate, so that the insulating substrate contacts the vibrating electrode even if the pressure of the insulating substrate is increased. There is no danger of Therefore, it becomes possible to obtain a high sealing property of the vibration space as compared with the conventional case.

Further, by continuously forming the conductive film on the inner surface and the side end surface of the second recess of the insulating substrate, the terminal electrode of the piezoelectric substrate and the external connection electrode of the insulating substrate can be surely conducted.

Furthermore, since only the first and second recesses are formed in the insulating substrate, both recesses can be easily formed by press molding, and the positions of these recesses can be set with high accuracy. Therefore, there is no variation in the positions of the vibration space and the second recess, and a high quality chip-type piezoelectric resonator can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view of an example of a chip type piezoelectric resonator according to the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is a plan view of a piezoelectric substrate, and FIG. 4 is an insulating substrate. A perspective view, FIG. 5 is a perspective view of the adhesive sheet, FIG. 6 is an exploded perspective view of the resonator base material, and FIG. 7 is a perspective view of the crimped state. 1 ... Piezoelectric resonator, 2 ... Piezoelectric substrate, 3,4 ... Electrode, 3a,
4a ... vibrating electrode, 3b, 4b ... terminal electrode, 5,6 ... vibrating space, 7 ... conductive film, 10 ... insulating substrate, 11 ... first recess,
12 …… Second recess, 20 …… Adhesive.

Claims (1)

[Scope of utility model registration request] 1. A piezoelectric substrate, and two insulating substrates having substantially the same shape as the piezoelectric substrate and sandwiching the piezoelectric substrate from both sides, and vibrating electrodes facing each other are formed in the central portions of both main surfaces of the piezoelectric substrate. , Terminal electrodes connected to the vibrating electrode are formed at opposite ends of both main surfaces, and the inner surface of the insulating substrate facing the main surface of the piezoelectric substrate corresponds to the vibrating electrode. A first concave portion is formed in a portion corresponding to the terminal electrode, and a second concave portion opening in a side end surface of the insulating substrate is formed in a portion corresponding to the terminal electrode, and external connection electrodes are formed at both end portions of an outer surface that does not face the main surface. Is formed on the opposing surface of the piezoelectric substrate and the insulating substrate, and parts other than the first and second recesses are bonded and fixed with an adhesive, and the terminal electrodes of the piezoelectric substrate and the outside of the insulating substrate are formed. The connection electrode is
A chip-type piezoelectric resonator characterized in that the second recess is electrically connected by a conductive film continuously formed on the side end surface on which the second recess is opened and on the inner surface of the second recess.