JP3261923B2 - Manufacturing method of built-in capacity type piezoelectric vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a piezoelectric vibrator with a built-in capacitor, and more particularly to a method of manufacturing a surface mount type piezoelectric vibrator.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional piezoelectric vibrator with a built-in capacitor used in a Colpitts type oscillation circuit. This vibrator includes an alumina substrate 1, a first capacitance electrode 2 is formed in the center of the upper surface, and external electrodes 3 are formed on both sides. The first capacitor electrode 2 and the external electrode 3 are formed in a headband shape on the peripheral surface of the substrate 1. A paste-like dielectric 4 is applied on the first capacitance electrode 2, and two second capacitance electrodes 5 are formed on the dielectric 4.
The main part is formed so as to oppose with the dielectric 4 interposed therebetween, and a part thereof is electrically connected to the external electrode 3. Two capacitors C are formed by the upper and lower capacitance electrodes 2 and 5 with the dielectric 4 interposed therebetween.
₁ and C ₂ are configured. A piezoelectric element 6 is mounted on the second capacitance electrode 5 with a conductive paste 9. After attaching the piezoelectric element 6 to the substrate 1, an alumina cap 7 is adhered to the substrate 1 with an adhesive 8 so as to cover the piezoelectric element 6, and the inside is sealed. FIG. 2 is a sectional view of the piezoelectric vibrator, and FIG. 3 shows an electric circuit thereof.

[0003]

In the case of the above-mentioned piezoelectric vibrator, when the piezoelectric element 6 is fixed to the substrate 1, the conductive paste 9 is used.
Flowed between the piezoelectric element 6 and the second capacitor electrode 5, and a stable vibration space S could not be secured. Therefore, the vibration characteristics may be unstable.

In order to solve this problem, a second capacitor electrode 5 is provided.
A method of securing a vibration space by providing a protruding spacer on the substrate may be considered. However, this method requires a separate step for forming the spacer, and has the disadvantage of increasing the number of steps and increasing the cost.

Accordingly, an object of the present invention is to provide a method of manufacturing a piezoelectric vibrator with a built-in capacitor that can stably secure a vibration space for a piezoelectric element without increasing the number of steps.

[0006]

To achieve the above object , the invention according to claim 1 is directed to a piezoelectric vibrator with a built-in capacitor.
A method of manufacturing, wherein a first material is provided on a substrate made of an insulating material.
Forming a capacitor electrode and two external electrodes, forming a dielectric layer on the first capacitor electrode to a constant thickness,
Providing a pair of spacers for forming a vibrating space made of a conductive material on the external electrodes, and forming a first portion on the spacers and on the dielectric layer with the main portion interposed between the dielectric layers. So that it faces the capacitor electrode and partly swells on the spacer
A step of applying a conductive paste to be a second capacitor electrode to two places, and a step of applying a piezoelectric element to the conductive paste before curing so that the electrode and the conductive paste on the spacer are electrically connected to each other. Attachment process and curing the conductive paste
A second capacitor electrode, and a piezoelectric element is formed on the second capacitor electrode by curing.
The second capacitor electrode and the first capacitor electrode
A step you form two capacitors between, is intended to include. Further, the invention according to claim 3 is a pressure-integrated pressure type.
A method for manufacturing an electric vibrator, comprising: a substrate made of an insulating material.
Forming a first capacitor electrode and two external electrodes thereon
And a dielectric layer having a constant thickness on the substrate including the first capacitance electrode.
And forming a pair of vibration spaces on the dielectric layer.
Providing a spacer, and a dielectric including the spacer
On the layers and on the external electrodes of the substrate, the main part is a dielectric layer
And the first capacitor electrode is opposed to the first capacitor electrode, and a part of each is an external electrode.
2 and a portion is raised on the spacer.
A step of applying a conductive paste to be a second capacitor electrode to a location
And a piezoelectric element on the conductive paste before curing
And the conductive paste on the spacer is electrically connected
Mounting the conductive paste and curing the conductive paste.
A two-capacitance electrode, and a piezoelectric element on the second capacitance electrode by curing
While fixing the second capacitor electrode and the first capacitor electrode.
Forming two capacitors between them.
is there. Further, the invention according to claim 5 is characterized in that the capacity built-in type
A method for manufacturing an electric vibrator, comprising: a substrate made of an insulating material.
Work to integrally form a pair of spacers for forming a vibration space on top
And a first capacitor electrode and two external electrodes on the substrate.
Forming and a constant thickness on the substrate including the first capacitance electrode
Forming a dielectric layer, on the spacer, the dielectric
On the layers and on the external electrodes of the substrate, the main part is a dielectric layer
And the first capacitor electrode is opposed to the first capacitor electrode, and a part of each of the first
2 and a portion is raised on the spacer.
A step of applying a conductive paste to be a second capacitor electrode to a location
And a piezoelectric element on the conductive paste before curing
And the conductive paste on the spacer is electrically connected
Mounting the conductive paste and curing the conductive paste.
A two-capacitance electrode, and a piezoelectric element on the second capacitance electrode by curing
While fixing the second capacitor electrode and the first capacitor electrode.
Forming two capacitors between them.
is there.

In the case of the first aspect, the first capacitor electrode and the second capacitor electrode are provided on the substrate.
After forming the external electrodes, a dielectric layer having a constant thickness is formed on the first capacitor electrode. And on the external electrode of the substrate
Is provided with a pair of spacers made of a conductive material, and a conductor serving as a second capacitor electrode is provided at two places on the spacer and on the dielectric layer.
Apply electric paste . The main part of conductive paste is
The first capacitor electrode is opposed to the first capacitor electrode with a dielectric layer therebetween, and a part thereof is
Make it rise on the spacer. This conductive paste
Before but to cure, the two ends of the piezoelectric element on the spacer
Place on the conductive paste and adhere. Due to the thickness of the spacer, a vibration space is formed between the piezoelectric element and the conductive paste (second capacitance electrode) . After bonding the piezoelectric element, Shirubedenpe
When the paste is cured, the second capacitance electrode is formed.
In particular, the piezoelectric element is fixed to the second capacitance electrode, and a capacitor is formed between the second capacitance electrode and the first capacitance electrode. This
As described above, since the second capacitance electrode has not only the capacitance forming electrode but also the function as the adhesive for fixing the piezoelectric element, the number of steps is not increased, and the increase in cost can be suppressed. In addition,
Since the capacitor is a conductor, the spacer and the second capacitance electrode
The electrodes of the piezoelectric element and the external electrodes are electrically connected via
It is. In the case of claim 3, the spacer is formed on the external electrode.
Instead of forming it on a dielectric. Therefore,
The pacer need not be a conductor, but may be an insulator.
No. Then, on the dielectric including the spacer and the substrate
Apply conductive paste to be the second capacitor electrode on the external electrode
I do. That is, in this case, the spacer is outside the piezoelectric element.
There is no function to connect the external electrodes. Similar to claim 1,
By bonding the piezoelectric element before the electric paste hardens,
The conductive paste to be the second capacitor electrode is only the capacitor forming electrode
Function as an adhesive for fixing the piezoelectric element.
One. Further, in the case of claim 5, the spacer is integrated with the substrate.
By forming it on the body, it has the same effect as in claims 1 and 3.
And must be formed later on external electrodes and dielectrics
There is no workability.

As a desirable method of forming the spacer, a paste-like resin or a conductive paste may be applied to positions on the dielectric layer corresponding to both ends of the piezoelectric element so as to be thicker than the thickness of the second capacitor electrode, and then cured. . In this case, since the spacers can be formed by a technique such as pattern printing similarly to the electrodes and the dielectric layers, high positional accuracy is obtained and mass productivity is improved. In the manufacturing method of the present invention, a first capacitor electrode, an external electrode, a dielectric layer, a spacer, and a second capacitor electrode are formed on a substrate at a stage of a mother substrate, and after a piezoelectric element is fixed, 1
A method of cutting each element is desirable in terms of productivity and positional accuracy.

[0009]

4 and 5 show a piezoelectric oscillator with a built-in capacitor according to an embodiment of the present invention. This oscillator has one piezoelectric element and two capacitors used in a Colpitts oscillation circuit, and its electric circuit is the same as that in FIG.

The substrate 10 has a thickness of 0.3 to 0.7 m formed by sheet or tableting of alumina ceramics.
In this example, a thin plate having a thickness of 0.5 mm was used. A first capacitor electrode 11 is formed at the center of the upper surface of the substrate 10, and two external electrodes 12 and 13 are formed at both ends of the upper surface. These electrodes 11 to 13 are formed by a known method such as sputtering, vapor deposition, printing, and thermal spraying. In this embodiment, in consideration of the fixing strength and the solderability,
Ag / Pd baking type conductive paste is 5-20μ
m, and baked at 850 ° C./10 minutes. The terminal portions 11a to 13a of the electrodes 11 to 13 are drawn out to the concave through-hole portions 10a formed on both side edges of the substrate 10, and are electrically connected to the electrodes formed on the inner surface of the through-hole portions 10a. Although not shown in FIG. 4, strip-shaped electrodes that are electrically connected to the electrodes 11 to 13 are also formed in a headband shape on the lower surface of the substrate 10.

On the first capacitor electrode 11 of the substrate 10 and on a portion corresponding to a cap bonding portion described later, a dielectric layer 15 is formed with a constant thickness. As a material of the dielectric layer 15, a resin-based paste or a glass-based paste is used. In this embodiment, a glass-based paste is used in consideration of insulation, moisture resistance, and the like. As a method for forming the dielectric layer 15, there are printing, transfer, dispensing, etc., but a pattern printing method capable of accurately controlling the thickness of the layer is desirable. The thickness of the dielectric layer 15 varies depending on the desired capacitance value. However, the thickness of the dielectric layer 15 is set so that unevenness due to the electrodes 11 to 13 is reduced, and sufficient insulation between the cap 25 described below and the electrodes 11 to 13 is ensured. For example, 20-1
It was about 00 μm. After printing, a drying process was performed, and a firing process was further performed at 700 to 850 ° C./10 minutes. In the dielectric layer 15 of this embodiment, a capacitance portion 15a that covers the first capacitance electrode 11 is formed in the center portion, and a frame-shaped bonding portion 15b corresponding to the cap bonding portion is formed in the outer peripheral portion. Two window holes 15c exposing a part of the external electrodes 12 and 13 are formed in the vicinity. Note that, instead of the above-described shape, the capacitance portion 15a and the bonding portion 15b may be separated.

Two spacers 18 and 19 are formed on the dielectric layer 15, particularly on the window hole 15c, by applying a predetermined thickness by pattern printing or the like, and then drying and curing. The spacers 18 and 19 are made of a conductive material such as a conductive paste. The thickness of the spacers 18 and 19 is set so that the spacers 18 and 19 are not buried when forming the second capacitance electrodes 16 and 17 described later and do not hinder the formation of the second capacitance electrodes 16 and 17. It is desirable to make the thickness larger than the thickness of the two capacitance electrodes 16 and 17. Specifically, the thickness is desirably about 0.01 to 0.50 mm.

Dielectric layer 1 including spacers 18 and 19
The second capacitor electrodes 16 and 17 made of conductive paste are applied on the layer 5 by a known method such as pattern printing. The material of the second capacitance electrodes 16 and 17 is preferably a material that is cured at a temperature at which the piezoelectric element 20 described below does not depole, or a material that is cured by drying. The main parts of the second capacitance electrodes 16 and 17 are opposed to the first capacitance electrode 11 with the capacitance part 15a of the dielectric layer 15 interposed therebetween.
Part of it is on the spacers 18,19. Therefore, the second capacitance electrodes 16 and 17 are respectively connected to the spacers 18 and
Conduction with the external electrodes 12, 13 via 19.

The piezoelectric element 20 to which the damping material 24 has been applied in advance is bonded to the second capacitor electrodes 16 and 17 before curing. The piezoelectric element 20 of this embodiment is a known thickness-shear vibration mode vibrator, and includes a piezoelectric substrate 21 made of piezoelectric ceramics or piezoelectric single crystal. An electrode 22 is formed over a region of about ／ from one end of the front surface of the piezoelectric substrate 21, and the electrode 2 is formed over a region of about ／ from the other end of the back surface.
3 are formed. One ends of the two electrodes 22 and 23 are opposed to each other at an intermediate portion with the piezoelectric substrate 21 therebetween, and constitute a vibrating portion. The vibrating portion is formed between the second capacitance electrodes 16 and 17 by the thickness of the spacers 18 and 19. A certain vibration space S is ensured so as not to contact. The other ends 22a and 23a of the electrodes 22 and 23 extend to the other surface via the end surface of the piezoelectric substrate 21. By adhering to the second capacitor electrodes 16 and 17 before curing as described above, the electrodes 22 and 23 of the piezoelectric element 20 are electrically connected to the second capacitor electrodes 16 and 17, respectively. After bonding, the second capacitance electrodes 16 and 17 are dried and cured.

The cap 25 is adhered to the substrate 10 by an adhesive 26 so as to cover the piezoelectric element 20. As a material of the cap 25, there are ceramics such as alumina, a resin, and a metal. In this embodiment, a metal material is used in order to reduce the size of the product and secure dimensional accuracy. The choice of metal material is arbitrary as long as the product strength and adhesiveness can be obtained, but in this case, nickel silver (Ni-Cu alloy) with a thickness of 0.15 mm
Press-molded was used. As the adhesive 26, an epoxy-based adhesive was applied by transfer to the bottom surface of the opening of the cap 25 by transfer, and then adhered onto the adhesive portion 15b of the dielectric layer 15 and cured.

As described above, the spacers 18 and 19 are formed on the dielectric layer 15, and the second capacitor electrodes 16 and 1 are formed thereon.
7 are formed, and the piezoelectric elements 2 and 17 are applied to the electrodes 16 and 17 before curing.
0 is bonded and fixed, so that the spacers 18 and 19 are fixed.
As a result, a stable vibration space S can be secured, and a piezoelectric vibrator having stable vibration characteristics can be obtained. Further, the total number of manufacturing steps does not increase as compared with the conventional case (see FIG. 1) and can be realized by the same processing as the conventional case, so that the manufacturing cost does not increase.

FIG. 6 shows a second embodiment of the present invention. In this embodiment, the same parts as those in FIG. In this embodiment, the spacers 18, 19
Is formed on the dielectric layer 15 and in a portion other than the window hole 15c and the first capacitance electrode 11, and a vibration space S is secured between the piezoelectric element 20 and the second capacitance electrodes 16 and 17. In this case, it is not necessary to use a conductive paste as the spacers 18 and 19, and a simple adhesive or a dielectric paste may be used.
The second capacitor electrodes 16 and 17 are applied on the dielectric layer 15 including the spacers 18 and 19, and a part thereof is also applied on the external electrodes 12 and 13 through the window hole 15c. for that reason,
The electrodes 22 and 23 of the piezoelectric element 20 are the second capacitance electrodes 16 and 1
7 and conduct with the external electrodes 12 and 13. As the spacer, a protrusion may be integrally formed on the substrate in advance, or a resin piece or a ceramic piece may be fixed on the substrate or the dielectric layer, instead of applying the paste.

When actually manufacturing the oscillator shown in FIG. 4, for example, electrodes 11 to 13 and a dielectric layer 1 are formed on a mother substrate.
5, electrodes 16, 17 and spacers 18, 19, etc. are simultaneously formed for a plurality of elements, and a plurality of piezoelectric elements 2 are formed on the mother substrate.
After attaching the 0 and the cap 25, the mother board may be cut one element at a time at the position of the through hole 10a to form the board 10. Also, the electrodes 11 to 1 are provided on the mother substrate.
3. After the dielectric layer 15, the electrodes 16, 17 and the like are formed simultaneously for many elements, the mother substrate is cut one element at a time, and the cut substrate 10 is provided with the piezoelectric element 20 and the cap 25.
May be attached one by one. Either method enables efficient mass production.

[0019]

As is apparent from the above description, claim 1
According to the invention, the conductive material on the external electrode on the substrate
Is provided on the spacer and the dielectric layer.
After applying the conductive paste for forming the second capacitor electrode, Shirubedenpe
Before the paste hardens, the two ends of the piezoelectric element are bonded together with the spacer placed on the spacer.Thus, the thickness of the spacer ensures a stable vibration space between the piezoelectric element and the substrate. A piezoelectric vibrator having stable characteristics can be obtained. In addition, since the conductive paste serving as the second capacitor electrode has both a function as a capacitor forming electrode and a function as an adhesive for fixing the piezoelectric element, the above effects can be achieved without increasing the number of steps and without increasing the cost. . Claim 3
According to the disclosure, a spacer is provided on the dielectric layer, and this space is provided.
Conductive pace that becomes the second capacitance electrode so that it rises above the substrate
The piezoelectric element is fixed on it.
Thus, the same effect as the first aspect can be achieved. Claim 5
According to the invention, the spacer is integrally formed on the substrate.
In addition, together with the effect of the invention according to claims 1 and 3, the spacer
Need not be formed on the external electrodes or the dielectric layer,
The manufacturing process is further simplified.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a conventional built-in capacity type piezoelectric vibrator.

FIG. 2 is a sectional view of the piezoelectric vibrator shown in FIG.

FIG. 3 is an electric circuit diagram of the piezoelectric vibrator shown in FIG.

FIG. 4 is an exploded perspective view of an example of a built-in capacitance type piezoelectric vibrator according to the present invention.

5 is a cross-sectional view of the piezoelectric vibrator shown in FIG.

FIG. 6 is a sectional view of another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 11 1st capacitor electrode 12, 13 External electrode 15 Dielectric layer 16, 17 2nd capacitor electrode 18, 19 Spacer 20 Piezoelectric element 25 Cap 26 Adhesive

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-140865 (JP, A) JP-A-57-178011 (JP, A) 38126 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H03H 3/00-3/04

Claims (5)

(57) [Claims] 1. A method of manufacturing a built-in capacitor type piezoelectric vibrator, comprising: forming a first capacitor electrode and two external electrodes on a substrate made of an insulating material; A step of forming a dielectric layer to a constant thickness, a step of providing a pair of spacers for forming a vibration space made of a conductive material on external electrodes of the substrate , and a main part on the spacers and the dielectric layer. dielectric layer opposite the first capacitor electrode and between the, and partially spacer
Conductivity that becomes the second capacitance electrode in two places so as to swell up
A step of applying a paste; a step of attaching a piezoelectric element to the conductive paste before curing so that the electrode and the conductive paste on the spacer are electrically connected; and a step of curing the conductive paste to form a second capacitor electrode. And cured
By fixing the piezoelectric element to the second capacitor electrode,
Two capacitors between the second capacitance electrode and the first capacitance electrode
Method of manufacturing a capacitor built-in piezoelectric vibrator comprising the steps that form a. 2. The manufacturing method according to claim 1, wherein the spacer induces a conductive paste on an external electrode of the substrate.
After coating thicker than the thickness of the electric conductor layer and the second capacitance electrode,
A manufacturing method characterized by being formed by curing. 3. A method for manufacturing a built-in capacity type piezoelectric vibrator.
A first capacitor electrode and two outer electrodes on a substrate made of an insulating material.
And forming a dielectric layer to a constant thickness on the substrate including the first capacitor electrode.
And providing a pair of spacers for forming a vibration space on the dielectric layer
On the dielectric layer including the spacer and on the external electrode of the substrate.
The main part is opposed to the first capacitor electrode with a dielectric layer in between.
Some of them are electrically connected to the external electrodes, and some are
The second capacitance electrode is formed in two places so that it rises above the capacitor
A step of applying a conductive paste and a step of applying a piezoelectric element to the conductive paste before curing with its electrodes.
Make sure that the conductive paste on the pacer is electrically conductive.
And curing the conductive paste to form a second capacitor electrode.
By fixing the piezoelectric element to the second capacitor electrode,
Two capacitors between the second capacitance electrode and the first capacitance electrode
Forming a piezoelectric vibrator with a built-in capacitor
Method. 4. The manufacturing method according to claim 3, wherein said spacer is a dielectric layer corresponding to both ends of the piezoelectric element.
A paste-like resin or conductive paste on the second capacitor
After applying it thicker than the thickness of the electrode,
A manufacturing method characterized by being formed. 5. A method of manufacturing a built-in capacity type piezoelectric vibrator.
To form a pair of vibration spaces on a substrate made of an insulating material.
Forming a pacer integrally, and forming a first capacitor electrode and two external electrodes on the substrate.
And that step, forming a dielectric layer at a constant thickness on a substrate comprising a first capacitor electrode
And on the spacer, the dielectric layer and the external electrode of the substrate.
The main part is opposed to the first capacitor electrode with a dielectric layer in between.
Some of them are electrically connected to the external electrodes, and some are
The second capacitance electrode is formed in two places so that it rises above the capacitor
A step of applying a conductive paste and a step of applying a piezoelectric element to the conductive paste before curing with its electrodes.
Make sure that the conductive paste on the pacer is electrically conductive.
And curing the conductive paste to form a second capacitor electrode.
By fixing the piezoelectric element to the second capacitor electrode,
Two capacitors between the second capacitance electrode and the first capacitance electrode
Forming a piezoelectric vibrator with a built-in capacitor
Method.