JPH05267743A - Manufacture of laminated piezoelectric actuator - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a laminated piezoelectric actuator, wherein the thickness of an electrodeposited coating (an insulating layer) on each one end part of internal electrodes formed every other layer is substantially ensured sufficiently and which has a high withstand voltage and an improved reliability. CONSTITUTION:A method of manufacturing a laminated piezoelectric actuator 17 comprises a process, in which piezoelectric ceramic plates 11 formed respectively with an internal electrode 12 are superposed, an etching is performed on each one end part of the electrodes 12 every other layer, an electrodeposited coating (an insulator) 15 is formed closely on the etched end parts of the electrodes 12 and the end parts, which are not etched, of the electrodes 12 are respectively connected with an external electrode 16.

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 laminated piezoelectric actuator, and more particularly to a method of manufacturing a laminated piezoelectric actuator used in fields such as tracking adjustment in a VTR or driving an auto focus lens in a camera. ..

[0002]

2. Description of the Related Art In response to demands for miniaturization and high functionality of electronic products, research and development for utilizing a laminated piezoelectric actuator in the field of mechatronics are being actively conducted. The laminated piezoelectric actuator has excellent controllability for minute displacements, high rigidity, and low power consumption. Currently, it is used for driving the autofocus lens of cameras and tracking adjustment for discs in CDs, VTRs, etc. Has been done.

The structure of a conventional laminated piezoelectric actuator is disclosed in, for example, Japanese Patent Publication No. Sho 63-17354, and the internal electrodes are formed on the entire surface of a piezoelectric ceramic plate to form an internal layer on the end surface of the laminated body. A structure is disclosed in which an insulating material that insulates electrodes every other layer is formed asymmetrically in a stacking direction by a pair of stacking end faces, and the internal electrodes are connected to external electrodes every other layer.

A method of manufacturing a laminated piezoelectric actuator is disclosed in Japanese Examined Patent Publication No. 2-34449 or Japanese Patent Laid-Open No. 63-6.
It is disclosed in Japanese Patent No. 5688. The process disclosed in Japanese Patent Laid-Open No. 63-65688 is shown in FIG.
(A) (b) (c) (d) (e) (f) (g).
First, the raw material powder is press-formed into a plate shape and sintered to form a piezoelectric ceramic plate 31 (FIG. 2A), and plating methods such as leaving internal electrode non-adhered portions 32a on both surfaces of the piezoelectric ceramic plate 31 Thus, the internal electrode 32 is formed (FIG. 2B), and the piezoelectric ceramic plates 31 on which the internal electrode 32 is formed are laminated and adhered to each other to form a laminated body 33 (FIG. 2C).
Next, a pair of laminated bodies 33 located at a position opposite to the laminated body 33.
Temporary external electrodes 34 are formed on the end faces (FIG. 2D), and an insulating layer 35 is formed in the inner electrode 32 portion and its vicinity at every other end face of the laminate 33 where the temporary external electrodes 34 are not formed by electrophoresis. Formed (FIG. 2E). External electrodes 36 that connect the exposed internal electrodes 32 are formed in the stacking direction (FIG. 2F), and the stacked body 33 is cut into a required width dimension to form a stacked piezoelectric actuator 37 (FIG. 2).
(G)).

[0005]

However, when the insulating layer 35 is formed by depositing an insulator by electrophoresis in a solution as in the method described above, depending on the insulator, a larger amount is deposited in the width direction than in the thickness direction. Some have the property to do. When such an insulator is used, there is a problem in that a sufficient thickness of the insulating layer cannot be maintained and the withstand voltage decreases.

The present invention has been invented in view of the above problems, in which the thickness of the insulating layer is substantially secured.
The internal electrode contacts both external electrodes, causing a short circuit,
It is an object of the present invention to provide a method for manufacturing a laminated piezoelectric actuator that does not lower the withstand voltage.

[0007]

In order to achieve the above-mentioned object, a method of manufacturing a laminated piezoelectric actuator according to the present invention comprises laminating and laminating plate-shaped piezoelectric ceramics having internal electrodes formed on a part of the surface thereof. After forming a body and forming two temporary external electrodes for electrically connecting the internal electrodes of the laminate alternately, and etching the end portions of the internal electrodes on one side surface of the laminate every other layer , After attaching an insulator for insulating the end of the internal electrode and etching the end of the internal electrode where one end of the internal electrode on the other side surface of the laminate is not insulated, Attach an insulator to insulate the ends of the internal electrodes,
It is characterized in that external electrodes are formed on both side surfaces of the laminate to connect ends of the internal electrodes not covered with the insulator, and then the temporary external electrodes are cut and removed.

[0008]

In the laminated body, the end portions of the internal electrodes are exposed on the end faces,
And every other layer is connected to a temporary external electrode. One side surface of the laminated body on which the temporary external electrode is not formed is masked with an insulating tape, and the laminated structure is immersed in an electrolytic solution that weakly etches the internal electrode. At this time, if an electrolytic substance that strongly corrodes the internal electrode is used, the internal electrode is totally damaged. Therefore, it is necessary to select an appropriate electrolytic substance, and a weak acid is generally preferable. ..

Next, the temporary external electrode is used as an anode, and a platinum plate or the like is used as a counter electrode, and this is used as a cathode for energization. As a result, the internal electrode on the side connected to the temporary external electrode is eluted as ions into the electrolytic solution from the exposed portion on the surface. On the other hand, the internal electrodes on the side not connected to the temporary external electrodes are hardly etched, and thus the internal electrodes exposed on the side surfaces are selectively etched.

When the laminated body is energized in the liquid in which the insulating material is dispersed to the same temporary external electrode as used in the etching to attach the insulating material, the internal electrode is etched by the insulating material. The resulting hollow portion is filled, and the thickness of the insulating layer is increased only in this portion, so that a highly reliable laminated piezoelectric actuator having a high withstand voltage can be obtained.

Further, the insulating tape on the side surface masked in the above step is removed, and the side surface on which the insulating layer is formed is newly masked by the insulating tape, and the temporary external electrode on the side different from the side used in the above step. Etching and electrophoresis are performed in the same manner as in the above steps. As a result, a laminated body is obtained in which the internal electrodes and the layers in which the internal electrodes are etched and the insulating material is attached to the surface layer portion are alternately repeated every other layer.

That is, according to the above-mentioned method, the end portion of the internal electrode is etched, and then the insulator is attached by the electrophoretic method, and the etched portion is filled with the insulator. The withstand voltage between the external electrode and the external electrode is improved, and dielectric breakdown during energization is prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a laminated piezoelectric actuator according to the present invention will be described below with reference to the drawings. Figure 1
(A)-(f) is a perspective view and a sectional view showing a manufacturing process of a lamination type piezoelectric actuator.

First, a piezoelectric ceramic containing lead zirconate titanate as a main component is sintered, and this sintered body has a width of 5 mm.
The piezoelectric ceramic plate 11 was formed by processing on a thin plate having a length of 60 mm and a thickness of 0.1 mm. Internal electrodes 12 made of nickel are formed by electroless plating on both main surfaces of the piezoelectric ceramic plate 11 so that the internal electrode non-adhered portions 12a of 3 mm are left symmetrically on the front and back sides (FIG. 1A). While applying the adhesive so that the non-adhered portions 12a are aligned with each other, 1
00 sheets (6 sheets in the figure) are laminated to form a laminated body 13.
Next, a conductive paste is applied to both side surfaces of the laminate 13 in the width direction to form temporary external electrodes 14, so that the internal electrodes 12 are electrically connected to the temporary external electrodes 14 every other layer. Lead wires (not shown) are connected to the temporary external electrodes 14 as lead electrodes (see FIG. 1).
(B)).

One of the side surfaces of the laminated body 13 on which the external electrodes 14 are not formed is masked with an insulating tape, and platinum of 3 cm square is placed as a counter electrode in 0.05 N hydrochloric acid so as to be parallel to each other. A voltage of 10 V was applied for 10 minutes with one of the extraction electrodes connected to the laminate 13 as a positive electrode and the platinum plate as a negative electrode. As a result, the exposed surface of the internal electrode 12 connected to the extraction electrode is etched by 20 μm on the surface not masked (FIGS. 1C and 1C ′).

Then, with this mask 13 being masked, a platinum plate of 3 cm square was placed as a counter electrode in an aqueous solution of an ultraviolet curing type electrodeposition paint so as to be parallel to each other, and an extraction electrode used for etching. Is used as a positive electrode, the platinum plate is used as a negative electrode, and a voltage of 5 V is applied for 10 minutes.
As a result, the electrodeposition coating material 15 is filled in the voids 18 formed by etching the internal electrodes 12, and the electrodeposition coating material 15 partially adheres to the surface. The electrodeposition paint 15 is irradiated with ultraviolet rays to be fixed (FIG. 1 (d)).

Next, the masking tape is peeled off, the surface to which the electrodeposition coating material 15 is attached is masked with the tape, and the other side of the extraction electrode is also used to perform etching and electrodeposition in the same manner to fix it by ultraviolet irradiation. (Fig. 1
(E)).

Further, silver paste is applied to one surface of the two side surfaces on which the temporary external electrode 14 is not formed, and the external electrode 1
6 is formed. After attaching a lead wire as an extraction electrode (not shown) from the external electrode 16, the temporary external electrode 14 is attached.
To remove. Through the above steps, the laminated piezoelectric actuator 17 in which the internal electrodes 12 are alternately electrically connected to or insulated from the external electrodes 16 is formed (FIG. 1).
(F)).

Table 1 shows the evaluation of withstand voltage between the thus-formed laminated piezoelectric actuator 17 and the conventional laminated piezoelectric actuator in which the exposed portion of the internal electrode 12 is not etched. This evaluation was performed by applying a voltage of 400 V at maximum between the two external electrodes 16 and measuring the current flowing there.

[0020]

[Table 1]

As is clear from Table 1, the withstanding voltage of the example is significantly higher than that of the comparative example.

Therefore, when the laminated piezoelectric actuator is formed by using the method according to this embodiment, the thickness of the electrodeposition paint 15 (insulating layer) is substantially secured, the withstand voltage is improved, and the reliability is high. A laminated piezoelectric actuator can be provided.

[0023]

As described above in detail, in the method of manufacturing the laminated piezoelectric actuator according to the present invention, the end portions of the internal electrodes are etched before the electrophoretic step of attaching the insulator. Since the steps are introduced, it is possible to provide a laminated piezoelectric actuator in which the thickness of the insulating layer of the insulating material is substantially secured and the withstand voltage is improved. Therefore, if the laminated piezoelectric actuator manufactured by the manufacturing method according to the present invention is used for an auto focus lens mechanism of a camera or the like, the reliability of the device can be improved.

[Brief description of drawings]

1A to 1F are a perspective view and a sectional view showing a manufacturing process in an embodiment of a method of manufacturing a laminated piezoelectric actuator according to the present invention.

2A to 2G are perspective views showing steps in a conventional method for manufacturing a laminated piezoelectric actuator.

[Explanation of symbols]

 11 Piezoelectric Ceramic Plate 12 Internal Electrode 13 Laminated Body 14 Temporary External Electrode 15 Electrodeposition Paint (Insulator) 16 External Electrode 17 Laminated Piezoelectric Actuator 18 Void

Claims (1)

[Claims] 1. Two temporary external devices for forming a laminated body by laminating plate-shaped piezoelectric ceramics having internal electrodes formed on a part of the surface thereof and electrically connecting the internal electrodes of the laminated body alternately. An electrode is formed, and after the end portions of the internal electrodes on one side surface of the laminate are etched by one layer, an insulator for insulating the end portions of the internal electrodes is attached,
After one end of the internal electrode on the other side surface of the laminate is not insulated, the end of the internal electrode is etched, and then an insulator is attached to insulate the end of the internal electrode. A method of manufacturing a laminated piezoelectric actuator, comprising forming external electrodes on both side surfaces of a body, connecting ends of the internal electrodes not covered with the insulator, and then cutting and removing the temporary external electrodes.