JP3236334B2 - Manufacturing method of piezoelectric actuator - 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 for manufacturing an electrode structure of a piezoelectric element constituting a piezoelectric actuator.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 59-96881.
According to the technology described in the publication, the effective electrode area for driving the piezoelectric body is only about 67% because the electrode connection pattern occupies the plane of the piezoelectric body, and sufficient characteristics cannot be obtained. FIG. 2 (d) shows a structure for solving this problem.
In the structure shown in (1), electrodes cannot be provided on the outermost peripheral portion and the innermost peripheral portion of one surface of the piezoelectric element. This is because a space for arranging a pattern for connecting to each other by using the outermost and innermost peripheral portions of the piezoelectric element so as to operate the twelve electrodes is provided.

Further, no electrodes are disposed on the outermost and innermost portions on the other surface facing the electrode connection pattern in order to prevent harmful vibration modes and characteristic deterioration (FIGS. 2 (a) to 2 (a)).
(b)) Therefore, there is a portion where the electric field is almost nonexistent in the thickness direction of the piezoelectric element, that is, in the direction connecting the front surface and the back surface.
That is, the innermost peripheral portion and the outermost peripheral portion of the piezoelectric element do not function when used as an actuator. This sacrifices the characteristics of the actuator.

Further, as shown in FIG. 3, the electrode pattern and the electrode connection pattern in a limited area in the plane of the piezoelectric body are determined by the electrode pattern area and the piezoelectric actuator performance, and the line width and the wiring resistance of the electrode connection pattern. Although the design is made based on the optimum value based on the correlation, in particular, in order to reduce the size of the piezoelectric element, the line width of the electrode connection pattern becomes relatively thin, and the wiring resistance increases. That is, the applied voltage is also increased, and the size of the peripheral parts of the piezoelectric actuator is required to be increased. The structure in which the electrode pattern and the electrode connection pattern in the piezoelectric body are arranged in the same plane is a bad effect in miniaturization. It is clear that they also have

A general manufacturing method for the electrode structure on these piezoelectric elements will be described below with reference to the process chart of FIG .
First, a plurality of divided electrode patterns 12a to 12n are formed on the same surface of the piezoelectric element 1 by vapor deposition of a metal thin film using a metal mask having a desired electrode shape (FIG. 2).
(a), (b)). Next, the electrode patterns 12a to 12n
The probe for voltage application is brought into contact with each other to perform each polarization process. Thereafter, a metal mask for forming the outermost peripheral electrode connection pattern 24c and the innermost peripheral electrode connection pattern 24a on which no electrodes are formed during the above-mentioned vapor deposition on the same plane as the electrode patterns 12a to 12n. Then, a metal thin film is deposited by using a metal mask (FIG. 2C), and then the outermost wiring electrode connection pattern 24b is formed by a metal thin film using a metal mask (FIG. 2D). . This manufacturing method is characterized in that a desired electrode pattern and electrode connection pattern structure can be obtained only by a technique of forming a metal thin film on a piezoelectric element.

[0006]

However, in the conventional method, the outermost and innermost peripheral portions for arranging the electrode connection patterns cannot be subjected to the polarization treatment.
The efficiency as an actuator or a motor is reduced due to the inability to operate due to the piezoelectric effect or the piezoelectric inverse effect. Further, in a structure in which an electrode pattern and an electrode connection pattern are arranged in the same plane, it is difficult to reduce the size of an actuator or a motor due to electrical problems such as wiring resistance. In order to avoid this problem, it is possible to arrange the electrode patterns in all possible ranges in terms of characteristics and to connect the electrodes with wires.

However, the presence of a large number of wires on the displaced actuator causes deterioration in characteristics, and also causes deterioration in characteristics due to the weight of the wires themselves.
Further, contact between wires may cause an obstacle such as a short circuit. That is, the problem that the piezoelectric element generated from the manufacturing method of the electrode formation of the piezoelectric actuator cannot sufficiently function originally has become apparent, and the problem of improving the characteristics and miniaturizing the piezoelectric actuator and the piezoelectric motor is presented. Was.

Accordingly, an object of the present invention is to solve the above-mentioned conventional problems by providing a new piezoelectric element for coupling arbitrary electrodes without deterioration in characteristics as an actuator and advantageous for miniaturization of the actuator. An object of the present invention is to provide a method for manufacturing an electrode of an actuator and obtain an improvement in characteristics of a piezoelectric actuator or a piezoelectric motor.

[0009]

According to the present invention, a piezoelectric element is adhered or fixed to an elastic body such as a metal, and a voltage is applied between a plurality of electrodes provided on the piezoelectric element. In the actuator for displacing the elastic body to move or rotate an object in contact with the elastic body, the electrodes are divided into a plurality of pieces on the same plane, and electrodes for selectively connecting each divided electrode are provided. The connection pattern is configured such that the electrically conductive wiring is formed with the electrode pattern requiring connection while the insulating pattern is insulated on the electrode pattern that is not electrically connected. Are arranged in a way. Further, as another example, without providing a three-dimensional wiring structure of the electrode pattern and the insulating material, the electrode connection pattern, the inner circumference different from the surface on which the electrode pattern of the piezoelectric element is arranged as shown in FIG.
A structure in which an electrode connection pattern is arranged on the outer side surface is also conceivable.

In these manufacturing methods, a piezoelectric material, a conductive material, and an insulating material are formed, or are formed by precipitation forming to correspond to an arbitrary piezoelectric element shape of various piezoelectric actuators.
The electrode pattern and the insulating pattern, the three-dimensional arrangement of the electrode connection pattern, and the electrode pattern and the electrode connection by combining the processes of application molding, deposition molding of the piezoelectric material and the conductive material and the insulating material on the elastic body, or combination of the processes of the application molding. The pattern can be arranged on different surfaces and side surfaces.

[0011]

In the piezoelectric actuator constructed as described above, a space of 100% of the plane of the piezoelectric material can be arranged as an electrode pattern, and an electrode for producing a desired piezoelectric effect can be added. In addition, the restriction on the line width of the electrode connection pattern is eliminated, and the wiring resistance is reduced, so that the characteristics of the piezoelectric actuator can be improved and the size of the piezoelectric actuator can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a method for manufacturing a piezoelectric actuator according to the present invention will be described below with reference to FIG.
In this embodiment, twelve divided electrode patterns are provided on the upper surface of the piezoelectric element of the piezoelectric motor, and the respective electrode wiring patterns are electrode patterns 2a, 2c, 2e, 2g, 2i, 2m.
And short-circuiting is performed, and the electrode patterns 2b, 2d, 2f,
2h, 2k, 2n, alternate wiring for short-circuit wiring,
An example of the entire conductive electrode 2p structure on the back surface of the piezoelectric element (FIG. 1 (j)).

1 is a piezoelectric element (Pb [Zr, Ti])
O ₃ ), a metal film (Cr, Ni, Au) formed on the surface of the piezoelectric element by a vapor deposition method using a metal mask at a substrate temperature of 1
At 40 ° C., an electrode pattern of 2a to 2n and a 2p electrode pattern on the back surface of the piezoelectric element were simultaneously deposited, and the thickness of the metal film at this time was controlled to 0.2 μm (FIGS. 1A to 1C). . Next, a voltage applying probe is brought into contact with the electrode patterns 2a to 2n, and the electrode patterns 2p on the back surface of the piezoelectric element are used as ground electrodes. Then, the Si
O ₂ is coated on the entire surface at a substrate temperature of 120 ° C. with a thickness of 1 μm, and the insulating material 13 is entirely coated (FIG. 1).
(b)-(e)).

Next, a resist pattern is formed in a desired shape by photolithography.
The shape is formed by etching using an HF etchant to form the insulating material 3 (FIGS. 1F and 1G). After this,
A coating having a thickness of 0.5 μm is applied to the entire surface of the Al electrode connecting material 14 for selectively connecting the electrode patterns by sputtering at a substrate temperature of 120 ° C. (FIGS. 2H and 2I). ). Next, a resist pattern is formed in a desired shape by photolithography, and the electrode connection material 14 is simultaneously formed into the electrode connection patterns 4a to 4b by etching using an etching solution of phosphoric acid.

By the above process, the electrode pattern 2a
2n, an insulating material 3, and a three-dimensional electrode structure of a piezoelectric element including the electrode connection patterns 4a and 4b (FIG. 1 (j)). FIG. 5 shows a second embodiment of the present invention, in which the shape of the piezoelectric element 11 of the piezoelectric actuator and the electrode patterns 32a to 32f are formed, and a raw material of the piezoelectric element is obtained by mixing PbO, TiO, and ZrO with a resin as an additive. In addition, Ag, C
And resin were mixed, and injection molding was performed at a constant time lag (FIG. 5 (a)). Thereafter, polarization processing was performed on each electrode pattern, and then a three-dimensional electrode structure of the piezoelectric element shown in FIG. 5B was formed through the same process as in FIGS. 1D to 1J.

FIG. 6 shows a third embodiment of the present invention.
The AlN powder and the resin as the insulating raw material are mixed with the piezoelectric element raw material obtained by mixing the powder and the resin and the electrode raw material obtained by mixing Ag, C and the resin, and injection molding is performed. 42f, conduction window 1 for short-circuiting an arbitrary electrode pattern and an electrode connection pattern to be formed thereafter
5 were formed simultaneously (FIG. 6A).
). Thereafter, polarization processing was performed on each of the electrode patterns 42a to 42f, and the three-dimensional electrode structure of the piezoelectric element of FIG. 5B was formed through the same process as in FIGS. 1H to 1J.

FIG. 7 shows a fourth embodiment of the present invention, in which the electrode patterns 2a to 2n are formed on the piezoelectric element 1 of the piezoelectric motor by sputtering (FIG. 7A). A varnish as a raw material of an insulating material is applied on the electrode patterns 2a to 2n by a spin coater, and the varnish is heated to 80 ° C and 120 ° C in a furnace.
Prebaking under the conditions of minutes, then exposure using a mask pattern for photolithography, continuous development, curing through heating in a furnace from 120 ° C to 400 ° C, conduction An insulating pattern 43 (polyimide) having a window 25 was formed (FIG. 7B). Thereafter, the piezoelectric element is placed in a furnace at 200 ° C. in an electrode pattern 2.
A voltage was applied to each of a to 2n to perform a polarization process.
Further, by the same process as in FIGS. 1 (h) to 1 (j), FIG.
(c) The three-dimensional electrode structure of the piezoelectric element was constructed.

FIG. 8 shows a fifth embodiment of the present invention, in which Al is used as a target and sputtering is performed on the front and back surfaces of the piezoelectric element 31 at a temperature of 120 ° C. to coat an Al thin film. I do. Next, a resist is formed in the shape of the electrode patterns 51a to 51n by photolithography, and the shape of the Al thin film is formed using phosphoric acid as an etchant (FIGS. 8A and 8B). Thereafter, each polarization process is performed using the electrode pattern. Further, FIG.
(a) Sputtering of an Al thin film on the front and back surfaces, the outer peripheral side surface, and the inner peripheral side surface by sputtering under the same conditions as in (a). A photolithography mask conforming to the inner peripheral shape was contact-fixed to the piezoelectric element 31, and exposure was performed.

Thereafter, development and post-baking treatments are performed to protect the entire surface of the electrode patterns 51a to 51n on the piezoelectric element and the entire surface of the electrode pattern 51p with the resist, thereby forming a resist having the shape of the electrode connection patterns 34a and 34b. The shape of the Al thin film was formed using phosphoric acid as an etchant to form the electrode structure of the piezoelectric element (FIGS. 8C to 8E). FIG. 4 shows a perspective view of the structure thus obtained.

In the embodiments of the present invention shown in FIGS. 1 and 5 to 7, all the insulating patterns and the electrode connection patterns are arranged at the vibration nodes in the plane of the piezoelectric element.
In the examples of FIGS. 4 and 8, it was confirmed that the line width of the electrode connection patterns on the inner peripheral side surface and the outer peripheral side surface was changed, and the vibration of the piezoelectric element was not suppressed at any line width.

When the torque, which is one of the characteristics of the piezoelectric actuator, was measured for all of the piezoelectric elements of the present invention constituted by the above-described manufacturing method, the piezoelectric actuator obtained by the conventional piezoelectric element manufacturing method (FIG. 2) was measured. Compared to
This resulted in a torque improvement of 26% to 31%. When the wiring resistance of the electrode connection pattern formed on the piezoelectric element was measured, the width of the conventionally designed electrode connection pattern could be set to 2 to 10 times in each embodiment. The result was 1/2 to 1/10 compared to. In addition, the yield in the production has conventionally been such that a defect often occurs due to short-circuit due to the overlap of the electrode pattern and the electrode connection pattern, and the yield of the electrode connection step is 68%. The occurrence of defects caused by short-circuits caused by overlapping electrode connection patterns has been eliminated. For this reason, in the embodiment of FIGS. 1, 4, 5, and 8, the yield of the electrode connecting step is 92%.
Up to 94%. Also, in the embodiment of FIGS. 6 and 7, the insulating pattern formed on the electrode pattern in the polarization process causes charge charging, resulting in a defect rate of 5% as compared with the other embodiments. In the other examples, the insulation failure of the insulation pattern that caused the failure was reduced, and the yield of the electrode connecting step was 99% to 99.5%.

[0022]

According to the present invention, as described above, the electrode connection patterns are eliminated from the same plane as the electrode patterns of the piezoelectric element, and the desired electrode patterns can be connected to each other without reducing the area of the electrode patterns to be connected. Since the connection is made, the characteristics of the piezoelectric vibrator can be maximized, and the characteristics of the piezoelectric actuator can be improved. Further, since the line width of the connection electrode pattern can be freely selected, the wiring resistance can be reduced, the electric efficiency of the piezoelectric vibrator can be improved, and the size of the piezoelectric actuator can be reduced. Further, in the manufacturing process of the piezoelectric actuator, there is an effect that the yield of the electrode connecting step which causes a reduction in the yield is improved, and an inexpensive piezoelectric actuator can be manufactured.

[Brief description of the drawings]

FIG. 1 is a process diagram showing a manufacturing process of a piezoelectric element electrode structure according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a manufacturing process of a conventional piezoelectric element electrode structure.

FIG. 3 is an explanatory diagram showing characteristics of a conventional piezoelectric element electrode pattern and electrode connection pattern structure.

FIG. 4 is a perspective view of a piezoelectric element electrode structure obtained according to another embodiment of the present invention.

FIG. 5 is a process chart of a second embodiment of the present invention.

FIG. 6 is a process chart of a third embodiment of the present invention.

FIG. 7 is a process chart of a fourth embodiment of the present invention.

FIG. 8 is a process chart of a fifth embodiment of the present invention.

[Explanation of symbols]

1, 11, 21, 31, 41 Piezoelectric materials 2a to 2n, 12a to 12n, 22a to 22n, 32a to 32f, 42
a to 42f electrode pattern 3, 13, 23, 33, 43 insulating material 4a, 4b, 24a, 24b, 24c, 34a, 34b electrode connection pattern

Claims (5)

(57) [Claims] A plurality of electrode patterns provided on an elastic body;
Piezoelectric element that displaces the elastic body by applying a voltage between them
In the method for manufacturing a piezoelectric actuator having a child, spa on the same surface of the piezoelectric element having a plane and any curved
One or more copies by
A step of forming a number of electrode patterns, a step of performing a polarization treatment according to each electrode pattern, a step of forming a shape of the insulating material by sputtering or CVD, thermal spraying, coating, printing, and a step of photolithographically etching the insulating material. Shape
A step of forming an electrode connection pattern for selectively connecting each electrode pattern by sputtering or vapor deposition, and forming the electrode connection pattern by photolithography etching.
Forming a piezoelectric actuator. 2. The process according to claim 1, further comprising the step of: simultaneously forming the piezoelectric element and the electrode pattern by injection molding or press molding in the process, and performing a polarization process in accordance with each electrode pattern. A method for manufacturing a piezoelectric actuator. 3. A process for simultaneously forming the electrode pattern and the insulating material, which are divided into a plurality of pieces on the same surface as the piezoelectric element, in the process, performing each polarization process, 2. The method for manufacturing a piezoelectric actuator according to claim 1, comprising the step of forming a pattern. 4. In the process, a step of forming a shape of the insulating material by sputtering or CVD, thermal spraying, coating and printing, and a step of forming the insulating material by photolithography and etching.
Ri and a step of shape forming, 130 ° C. ~ for insulating material secured
2. The method for manufacturing a piezoelectric actuator according to claim 1, comprising a step of performing a polarization treatment in accordance with each electrode pattern after a step of performing a heat treatment at 800 ° C. and a step of forming an electrode connection pattern. 5. An electrode connection pattern for selectively connecting the electrode pattern to the outer peripheral side surface and the inner peripheral side surface through a step of performing a polarization process using a plurality of electrode patterns provided on the piezoelectric element, and forming the shape by sputtering, vapor deposition, or printing. Process and shape forming by photolithography and etching
The method for manufacturing a piezoelectric actuator according to claim 1, comprising: