JP2508323B2 - Method of manufacturing laminated piezoelectric actuator - Google Patents

Description

The present invention relates to a method for manufacturing a laminated piezoelectric actuator, and more particularly to a method for manufacturing a full-surface electrode type laminated piezoelectric actuator.

[Conventional technology]

A piezoelectric element having a multilayer capacitor structure is an excellent actuator that generates large strain at low voltage. For this reason, this piezoelectric actuator is used in a manufacturing apparatus for various electronic components such as semiconductors that are subjected to microfabrication, an optical apparatus that requires fine positioning, and the like. Further, a laminated piezoelectric actuator in which such a piezoelectric element and an electrode plate are alternately laminated to generate a large amount of strain has been put into practical use, and in recent years, the laminated type actuator has been used for a control part such as a head for a dot printer. Piezoelectric actuators are being used.

Among such laminated piezoelectric actuators, there is also a laminated piezoelectric actuator having a structure in which internal electrodes are provided by printing electrodes on the entire laminated surface of a piezoelectric plate composed of piezoelectric elements.
In this structure, the ends of the internal electrodes appear on the side surfaces of the laminate with a width of several microns. And conventionally, this internal electrode was connected to the external electrode by the method as shown in FIGS. 12 to 14.

That is, on the exposed surface of the internal electrode 2 of the laminated body in which the piezoelectric plate 1 and the internal electrode 2 are laminated, the plating layers 20 are provided every other layer in FIG. 12, and these are connected to the power source by the lead wire 21. , First
In FIG. 13, an electrically conductive printed layer 32 is provided on the exposed surface and an electrically conductive printed layer 32 is provided on every other layer, and this is connected to a power source.
In FIG. 14, a glass layer 41 is provided on every other exposed surface for insulation, and then a plated layer 42 is provided.
Is applied and is connected to a power source (the method of FIG. 14 is disclosed in JP-A-61-234579).

However, no matter how the external electrode is attached to the linear internal electrode that appears on the side surface of the laminated body from the outside, the external electrode is temporarily coupled to the internal electrode. Does not bond very well, and the external electrodes are easily peeled off. Even if the external electrode and the internal electrode are well coupled, the width of the internal electrode end portion in the thickness direction is only a few microns, so when the external electrode is peeled off from the ceramic, It is difficult to endure external vibrations and other disturbances without tearing only at the width. As described above, it is a difficult technique to attach a lead-out port to the external electrode that is reliable and highly reliable, to the linear internal electrode that appears on the side surface of the laminated body.

Therefore, as shown in FIGS. 15 and 16, the piezoelectric plate 1
There is also a laminated piezoelectric actuator having a structure in which piezoelectric pellets 3 each having an internal electrode 2 having a conductive agent printed on only one surface thereof are laminated while being displaced by a slight amount (for example, 0.1 to 1.0 mm) in the left-right direction. In the laminated piezoelectric actuator having this structure, the internal electrode 2 projects from the laminated body and has a large area at the exposed end of the internal electrode 2, so that the external electrode can be taken out easily and reliably.

[Problems to be Solved by the Invention]

However, in the laminated piezoelectric actuator having the structure shown in FIGS. 15 and 16, the piezoelectric plate 1 at the portion where the upper surface (eg, the positive electrode) and the lower surface (eg, the negative electrode) face each other normally expands and contracts. The protrusion 1a of the formed piezoelectric plate 1 does not expand or contract normally because the internal electrodes 2 are not printed on both sides thereof. Therefore, since unreasonable stress is generated at the boundary with the normal operation part, a crack is generated in the part during repeated operation, and the cavity of the crack has a small dielectric strength, so that high-voltage discharge is generated there. There is a problem of running and catastrophic destruction.

In order to solve such a problem, the present invention provides a full electrode type laminated body which is capable of reliably and firmly bonding the outer peripheral end (exposed end) of an internal electrode and an external electrode formed by plating or printing. It is an object of the present invention to provide a method of manufacturing a laminated piezoelectric actuator having the outer peripheral edge (exposed edge) shape of the internal electrode.

[Means for solving the problem]

The laminated piezoelectric actuator of the present invention to achieve the above object, the entire circumference or a part of the outer peripheral side surface of the plate-shaped piezoelectric element,
A step of forming a non-piezoelectric element of a bearing by fixing a metal or resin bearing whose position in the height direction at least partially coincides with the upper surface of the piezoelectric element by means such as plating or bonding, and the piezoelectric element with the bearing. A step of making a piezoelectric element pellet with a support by forming a thin film internal electrode on one side of the element by printing a conductive agent, plating of multi-electrode metal, or vapor deposition, and a plurality of piezoelectric element pellets with this support Is divided into a positive electrode and a negative electrode, and a step of forming a laminated body by using an adhesive while aligning the respective external electrode lead-out portions on the same side, and a plurality of side surfaces of the laminated body. The support is removed by electrodissolution, chemical dissolution, dissolution with an organic solvent, etc., and a part of the internal electrode is projected to the side surface of the laminate, and a part of the internal electrode projecting on the same side is electrically connected. Combine It is characterized by comprising a step of forming a part electrode.

[Action]

According to the method for manufacturing a laminated piezoelectric actuator of the present invention, the inner electrode is extended to the outer side more than the outermost peripheral side wall position of the piezoelectric element supporting the inner electrode in the entire outer periphery or a part of the outer periphery. And a protruding stack is obtained. That is, the internal electrode has a thin plate protruding portion that slightly extends into the hollow not supported by the piezoelectric plate, and the protruding length is 0.05 to
The thickness is 0.5 mm, and the thickness is a few microns to several tens of microns. Therefore, the thin plate projecting portions can be used as individual external terminal portions, and every other one of them can be electrically coupled to form an external electrode.

〔Example〕

An embodiment of a method for manufacturing a laminated piezoelectric actuator of the present invention will be described in detail below with reference to the accompanying drawings.

1 to 8 are views for explaining a method of manufacturing a laminated piezoelectric actuator according to an embodiment of the present invention.

When manufacturing piezoelectric laminates, lead zirconate titanate Pb
A small amount of an organic binder was added to a piezoelectric material calcined powder containing (Ti _x Zri _-x ) O ₃ [molar ratio at x = 0.4 to 0.6] as a main component, and this was dispersed in an organic solvent. Prepare the slurry first. Then, the slurry is applied to a mylar film to a thickness of 600 μm and dried by a casting film forming apparatus used for manufacturing a usual monolithic ceramic capacitor. Subsequently, this is peeled from the film to manufacture a piezoelectric material green sheet. Cut this green sheet into a circle with a diameter of 30mm.
A piezoelectric plate 1 having a uniform size as shown in the figure is produced. Next, the circular green sheet is fired at about 1250 ° C., and if necessary, the upper and lower planes are processed by grinding or lapping to finish.

As shown in FIG. 2, a support 4 is formed by plating on the cylindrical side surface of the piezoelectric plate 1 thus manufactured, and a piezoelectric element 5 with a support is manufactured. Since the plating method is used in this embodiment, the support 4 is formed substantially uniformly from the upper surface to the lower surface of the piezoelectric plate 1. Further, excessive adhesion of plating on the upper surface and the lower surface is removed by grinding or lapping. Copper is used as the metal to be plated, for example.
The thickness of the support 4 is 0.05 to 0.5 mm. Generally, this thickness is set thin when the thickness of the internal electrode in the subsequent step is thin, and set thick when it is thick.

The support 4 may be formed by coating the side surface of the piezoelectric plate 1 with a resin material that is easily dissolved by a solvent. In this case, some kind of pretreatment, for example, resin etching treatment, is performed as necessary in order to ensure the adhesion of the internal electrodes in the subsequent step.

Next, as shown in FIG. 3, the internal electrodes 2 are formed by plating on the entire upper surface of the piezoelectric element 5 with the supporting body to manufacture the piezoelectric element pellet 6 with the supporting body. When a thin metal film is attached as a base of plating by vapor deposition and then plating is performed, a good plating layer can be obtained. At this time, if necessary, the upper surface of the piezoelectric element 5 with a support is subjected to pretreatment such as liquid honing, shot blasting, etching and the like. At this time, the plating layer may contain reinforcing fibers.

Then, the piezoelectric element pellets 6 with bearings manufactured in this manner are coated with a conductive adhesive 7 on the laminated surface, and then the other piezoelectric element pellets 6 with bearings are laminated and adhered thereon. After stacking the required number of sheets, shims made of piezoelectric material may be stacked on the top and bottom. The laminated piezoelectric plate 1 and internal electrode 2 are pressure-bonded and integrated by hot pressing, and then a conductive adhesive is baked at about 550 ° C. and fixed to form a laminated body 8.

After that, the metal of the support 4 is electrochemically or chemically dissolved to form a space 9 having no support on the side surface of the laminate 8. Due to the disappearance of the support 4, the internal electrode 2
The end portion of is formed with a protruding portion 2A which is a thin metal piece protruding into the air. At this time, even if the protruding portion 2A of the internal electrode 2 is a thin piece, it is generated by a melting action without external force, so that a desired protruding shape can be obtained without causing inconvenient deformation. Further, when the support 4 is made of a resin material, the same protrusion 2A can be obtained by removing the support 4 with an organic solvent.

The protruding portion 2A made as described above may be plated more intensively on the protruding portion 2A so as to be thickened to increase the strength.

After this, as shown in FIG. 6, the external electrode forming portions of the protruding portions 2A are covered with an insulating agent 11 every other layer, and the insulating agent 11 and the exposed protruding portions 2A are both covered from above as shown in FIG. The external electrode 12 is covered with the external electrode 12, and the exposed protruding portion 2A is electrically coupled with the external electrode 12. The external electrode 12 can be formed by plating. FIG. 8 shows an external view of the laminated piezoelectric actuator 10 manufactured by the manufacturing method of the present invention. The external electrodes 12 may be connected to a positive power source and a negative power source, respectively.

In addition, the protrusion 2A of the internal electrode 2 is formed by electroplating,
As a method of connecting the negative terminal of the plating power supply to the internal electrode 2 when covering with a plating layer with a thickness of 0.05 to 0.3 mm to increase the thickness, use a portion of the protruding portion 2A that does not require thickening. Alternatively, a minus jig connected to the minus terminal may be pressed to apply the plating current in a state in which the protruding portion 2A at that portion is pressed against the jig and crushed.

Further, as shown in FIG. 17, the glass layer 13 selectively adhering only to the piezoelectric plate 1 is provided on the side surface of the piezoelectric plate 1 within such a range that half or more of the protruding length of the protruding portion 2A is not buried. In the inside, it is applied to the side surface of the piezoelectric plate 1 with a sufficient thickness, and at this time, the glass layer 13 is thinnest in the vicinity of the protruding portion 2A by utilizing the characteristics of selective application, while the other one piezoelectric material is used. It is formed as a mountain-shaped glass layer that becomes the thickest in the vicinity of the central height in the thickness direction of the plate 1, and then the plus-side protrusion 2A (+)
The negative side internal electrode exposed end in the vicinity of or the negative side protruding portion 2A (-) is insulation-coated with the insulating agent 11, and then the conductive paint is vertically printed in a strip shape from above. An external electrode (not shown) that electrically connects the above-mentioned plus-side protruding portion 2A (+) may be configured.

9 to 11 show another embodiment of the method for manufacturing a laminated piezoelectric actuator according to the present invention.
3 shows a manufacturing method in which the protruding portion 2A is partially provided. In this embodiment, as shown in FIG. 9, a resin-made bearing 4 having a portion equal to the height of the piezoelectric plate 1 and another portion lower than the height of the piezoelectric plate 1 is prepared. The piezoelectric plate 1 is fitted into the inner peripheral portion of the above to prepare a piezoelectric element 5 with a bearing as shown in FIG. Then, as shown in FIG. 11, an internal electrode 2 is formed on a part of the piezoelectric plate 1 and a part of the supporting body 4 which are flush with each other to form a piezoelectric element pellet 6 with a supporting body. The layers are alternately laminated so as to face the opposite side to form a laminated body 8 in the same state as that shown in FIG.

Then, after that, the resin of the support body 4 is removed with an organic solvent, so that the laminated body 8 in which the protruding portions 2A are present at alternate layers on both sides of the side surface is formed. Then, the electrode on the opposite side is exposed flush with the side surface of the laminate. Therefore, in this case, a glass layer that easily adheres to the piezoelectric plate 1 is formed as an insulating layer on the surface of the laminated body 8 that is lower than the height of the protrusion 2A,
An external electrode can be formed on it.

〔The invention's effect〕

As described above, according to the manufacturing method of the present invention, in the laminated body that does not use the internal electrode plate, the extraction of the external electrode is surely made firm, and the reliability of the joint is improved.
Also, when setting the process by combining the coating of the glass layer and the application of the insulating agent, the outer peripheral edge of the internal electrode is
Trouble of being buried by mistake is greatly reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a piezoelectric plate used in the manufacturing method of the present invention,
2 (a) and 2 (b) are a perspective view and a front sectional view of a piezoelectric element with a support, and FIGS. 3 (a) and 3 (b) are a perspective view and a front sectional view of a piezoelectric element pellet with a support. Fig. 4 is a cross-sectional view of a laminated body in which the piezoelectric element pellets with the support are laminated, Fig. 5 is a side view of the laminated body with the support removed, and Fig. 6 is one layer of the internal electrode 2 of the laminated body of Fig. 5. FIG. 7 is a partial sectional view showing a state of being insulated with an insulating agent, FIG. 7 is a partial sectional view showing a state of forming an external electrode on the laminated body of FIG. 6, and FIG.
FIG. 9 is a perspective view showing the appearance of a laminated piezoelectric actuator manufactured by the manufacturing method shown in FIG. 9, FIG. 9 is a perspective view of a piezoelectric plate and a support used in a manufacturing method of another embodiment of the present invention, and FIG. Perspective view of the piezoelectric plate shown in the figure and the support fitted together.
FIG. 11 is a perspective view of a piezoelectric element pellet with a support obtained by forming internal electrodes on the piezoelectric element with a support of FIG. 10, and FIG.
FIG. 14 is a partial sectional view showing an external electrode structure in a conventional full-surface electrode type laminated piezoelectric actuator, and FIGS. 15 and 16 are partial sectional views showing a structure of a conventional partial electrode type laminated piezoelectric actuator. FIG. 17 is a partial sectional view showing the structure of still another embodiment of the present invention. 1 ... Piezoelectric plate, 2 ... Internal electrode, 2A ... Projection part, 4 ...
Support, 5 ... Piezoelectric element with support, 6 ... Piezoelectric element pellet with support, 7 ... Conductive adhesive, 8 ... Laminated body, 10
...... Multilayer piezoelectric actuator manufactured by the manufacturing method of the present invention, 11 …… Insulating agent, 12 …… External electrode.

Claims (1)

(57) [Claims] 1. A metal or resin bearing body, at least a portion of which in the height direction corresponds to the upper surface of the piezoelectric element, is plated or bonded to the entire circumference or a part of the outer peripheral side surface of the plate-shaped piezoelectric element. The step of making a piezoelectric element with a support by fixing it by means of, and forming a thin film internal electrode on one side of this piezoelectric element with a support by printing conductive agent, plating metal for electrodes, or vapor deposition. , The step of making the piezoelectric element pellet with the support, and the multiple piezoelectric element pellets with the support are divided into positive electrode and negative electrode, and the adhesive is applied while aligning the external electrode extraction parts on the same side. A step of forming a laminated body by using the laminated body, and removing a plurality of supporting bodies located on the side surface of the laminated body by electrodissolution, chemical dissolution, dissolution with an organic solvent, etc. Project to the side of the body Floors and, phase and method for manufacturing a piezoelectric laminate to produce a piezoelectric laminate by forming the electrically coupled to the external electrode portions protruding on the same side of the internal electrode.