JP2014072260A - Method of manufacturing piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a piezoelectric actuator capable of improving positional accuracy of an internal electrode and a recess without increasing warpage and deformation of a piezoelectric element.SOLUTION: A method of manufacturing a piezoelectric actuator 1 including a piezoelectric element 2 which ultrasonically vibrates and a friction member 4 which is fixed at a recess 3 formed on one surface 2a of a piezoelectric element 2 and transmits ultrasonic vibrations comprises the steps of: forming a ceramic green sheet in which a plurality of pre-burning piezoelectric element regions 15 serving as a rectangular piezoelectric element after burning are arranged in a lattice shape and forming a conductor layer serving as an internal electrode 10 after burning in the pre-burning piezoelectric element region 15; forming a ceramic green sheet laminate 16 by laminating a plurality of ceramic green sheets; and forming a recess 3 in a direction equivalent to a width direction of the pre-burning piezoelectric element region 15 by grinding an outer surface of the ceramic green sheet laminate 16.

Description

  The present invention relates to a method for manufacturing a piezoelectric actuator, and more particularly, to a method for manufacturing a piezoelectric actuator provided with a friction member for driving a driven body.

As a piezoelectric actuator, a piezoelectric element, and a friction member that is fixed in part in a recess formed on one surface of the piezoelectric element and that makes contact with the driven body to generate a frictional force between the driven body, The one with is known.
6 shows the structure of such a piezoelectric actuator, FIG. 6 (a) is a perspective view thereof, and FIG. 6 (b) is a sectional view taken along line XX of FIG. 6 (a). In the figure, a piezoelectric actuator 51 has two recesses 53 formed on one surface 52 a of a piezoelectric element 52 in parallel with the width direction of the piezoelectric element 52, and a rod-shaped friction member 54 is fixed to each recess 53. . A part of the friction member 54 is embedded in the recess 53, the other part protrudes from the one surface 52 a, and the uppermost part is pressed against one surface of the flat plate as the driven body 55. The piezoelectric element 52 is configured as a laminated body in which a ceramic insulating layer 62, an internal electrode 60, and a ground electrode 63 are laminated. The internal electrode 60 is connected to a power supply terminal 61 on the other surface 52b of the piezoelectric element 52 through a through conductor (not shown), and the ground electrode 63 is connected to a ground terminal 64 on the other surface 52b of the piezoelectric element 52 through a through conductor (not shown). Connected to.
In such a configuration, when a voltage is applied from the outside to the power supply terminal 61 and the ground terminal 64 and the piezoelectric element 52 vibrates, a frictional force is generated between the friction member 54 and the driven body 55, and the driven body 55 is Will move.

A general manufacturing method of the piezoelectric actuator 51 will be described with reference to FIGS.
(1) Firing ceramic parent substrate forming step A raw material powder made of PbO, TiO ₂ , ZrO ₂ or the like is kneaded together with an organic solvent and a binder. This is formed into a sheet shape to produce a plurality of ceramic green sheets. Next, a through hole is formed in the ceramic green sheet as necessary, and the through hole is filled with a conductor paste for a through conductor serving as a through conductor, and an internal electrode 60 and a ground electrode 63 are formed on one main surface of the ceramic green sheet. A conductor layer to be formed is deposited. In addition, a conductor layer serving as the power terminal 61 and the ground terminal 64 is formed on the ceramic green sheet constituting the other surface 52 b of the piezoelectric element 52.
The ceramic green sheets thus formed are laminated to produce a ceramic green sheet laminate. The obtained ceramic green sheet laminate is fired at a firing temperature of 800 to 1200 ° C. to form a fired ceramic parent substrate 57 in which a plurality of piezoelectric element regions 56 shown in FIG. Next, in order to make the polarities of the piezoelectric materials uniform, a polarization process is performed by a known method.
(2) Concave Forming Step Next, the dicing saw 59 that rotates at a high speed shown in FIG. The cross section of the recess 53 is formed in a shape corresponding to the embedded portion of the friction member 54. In FIG. 7B, the recess 53 has a semicircular cross section.
(3) Cutting / Friction Member Adhering Step Thereafter, the fired ceramic parent substrate 57 is cut along the boundary line 58 into individual pieces. Finally, the friction member 54 is fixed to the recess 53 with an adhesive.

When the ceramic green sheet laminate is fired, shrinkage occurs, but the shrinkage is not uniform and deformed. That is, as shown in FIG. 8 (a), even if it is a square ceramic green sheet laminate, the center portion of each side is greatly shrunk as shown in FIG. 8 (b) by firing it. In other words, as shown in FIG. 8C, a sintered ceramic parent substrate 57 in which the vicinity of both ends of each side is greatly shrunk is obtained. Due to such irregular shrinkage, the arrangement of the internal electrodes formed by firing changes correspondingly.
However, since the dicing saw is moved linearly, as shown in FIGS. 8B and 8C, a linear recess 53 is formed in the sintered ceramic parent substrate 57 that has been deformed and deformed. Since the recess is formed in such a state, the position of the recess 53 with respect to the internal electrode 60 is displaced. Such a positional shift is not preferable because it causes disturbance in the vibration mode of the piezoelectric element 52.
Furthermore, in the method of forming the concave portion 53 by dicing on a brittle and hard ceramic sintered body, there is a problem that a running cost due to wear of the dicing saw occurs.

Patent Document 1 discloses an invention aimed at addressing such problems.
The invention described in Patent Document 1 includes a piezoelectric / electrostrictive ceramic laminate including an electrode film therein, and a sliding body provided on the surface of the piezoelectric / electrostrictive ceramic laminate for sliding an object. A method of manufacturing a sonic motor, wherein (a) a plurality of green sheets whose movement in a spreading direction is restricted with respect to a protrusion of a stacking jig on which a protrusion is formed are directed toward a protrusion forming surface of the stacking jig. A step of pressing, (b) a step of firing the pressure-bonded body of the plurality of green sheets obtained in the step (a) to obtain the piezoelectric / electrostrictive ceramic laminate, and And fitting the sliding body into a groove formed on the surface of the piezoelectric / electrostrictive ceramic laminate by pressing.
According to the invention of Patent Document 1 described above, the groove is formed by pressing the green sheet toward the projection forming surface in a state where movement of the green sheet in the spreading direction with respect to the stacking jig is restricted. The position shift of the sliding body for sliding the object can be suppressed.
Furthermore, the above method does not generate running costs due to wear of the dicing saw.

JP 2009-247115 A

In the green sheet press-bonded body pressed by the manufacturing method of Patent Document 1, the density of the portion compressed by the protrusion during pressing is higher than the density of the other portions. When a green sheet pressure-bonded body having different density depending on the location is fired, warpage and deformation of the fired piezoelectric / electrostrictive ceramic product increase. Variations in the size and shape of the piezoelectric / electrostrictive ceramics affect the resonance frequency of the piezoelectric / electrostrictive ceramics. Therefore, if the size and shape of the piezoelectric / electrostrictive ceramics vary, the resonance frequency of the piezoelectric / electrostrictive ceramics There is a problem of variation.
The present invention provides a method of manufacturing a piezoelectric actuator that can improve the positional accuracy of internal electrodes and recesses without increasing the warpage or deformation of the piezoelectric element, and can suppress variations in the resonance frequency of the piezoelectric element. Objective.

A method of manufacturing a piezoelectric actuator according to claim 1 of the present invention for solving the above-described problem is to transmit a piezoelectric element that vibrates ultrasonically and the ultrasonic vibration that is fixed to a recess formed on one surface of the piezoelectric element. A method of manufacturing a piezoelectric actuator having a friction member
Forming a ceramic green sheet in which a plurality of pre-fired piezoelectric element regions to be rectangular piezoelectric elements after firing are arranged in a grid, and forming a conductor layer to be an internal electrode after firing in the pre-fired piezoelectric element regions; ,
Laminating a plurality of the ceramic green sheets to form a ceramic green sheet laminate;
A method for manufacturing a piezoelectric actuator comprising the step of grinding the outer surface of the ceramic green sheet laminate to form the recess in a direction corresponding to the width direction of the piezoelectric element region before firing.

According to the method for manufacturing a piezoelectric actuator according to claim 1 of the present invention, since the concave portion is formed by grinding the outer surface of the ceramic green sheet laminate before shrinkage, the conductor layer and the concave portion serving as the internal electrode The position accuracy of the is improved. Moreover, since the green sheet laminated body is not pressed during the formation of the recess, the density in the vicinity of the recess does not become higher than the density of other portions. Therefore, warping and deformation of the fired piezoelectric element due to the formation of the recess can be prevented. For this reason, the dispersion | variation in the resonant frequency of a piezoelectric element can be suppressed.
Furthermore, since the outer surface of the ceramic green sheet laminate is ground, it is possible to prevent the occurrence of chipping and cracking that are problematic during processing of the fired body.
In addition, the grinding speed can be improved and the dicing saw can be prevented from being damaged or worn, so that the processing time can be reduced and the processing cost can be reduced.

(A) The perspective view of the piezoelectric actuator manufactured by the manufacturing method of this invention, (b) Sectional drawing along the AA of (a). The figure for demonstrating the ceramic green sheet laminated body formation process among Example 1 of this invention. The figure for demonstrating a recessed part formation process among Example 1 of this invention. The figure for demonstrating an individualization and baking process among Example 1 of this invention. The figure for demonstrating Example 2 of this invention. (A) The perspective view of the piezoelectric actuator of a prior art example, (b) Sectional drawing along the XX line of (a). (A) The figure for demonstrating the baking ceramic parent substrate formation process among the manufacturing methods of the piezoelectric actuator of a prior art example, (b) For describing the recessed part formation process among the manufacturing methods of the piezoelectric actuator of a prior art example Figure. (A) Plan view showing a ceramic green sheet laminate for explaining deformed contraction, (b) Plan view showing an example of a fired ceramic parent substrate obtained by firing the ceramic green sheet laminate, (c) Ceramic The top view which shows the other example of the sintered ceramic parent board | substrate obtained by baking a green sheet laminated body.

FIG. 1A is a perspective view of a piezoelectric actuator manufactured by the manufacturing method of the present invention, and FIG. 1B is a cross-sectional view taken along line AA of FIG. In this piezoelectric actuator 1, two concave portions 3 are formed in parallel on one surface 2 a of the piezoelectric element 2, and a rod-like friction member 4 is fixed to each concave portion 3. A part of the friction member 4 is embedded in the recess 3, the other part protrudes from the one surface 2 a, and the uppermost part is pressed against one surface of the flat plate as the driven body 5. The piezoelectric element 2 is configured as a laminated body in which a ceramic insulating layer 12, an internal electrode 10, and a ground electrode 13 are laminated. The internal electrode 10 is connected to the power supply terminal 11 on the other surface 2b of the piezoelectric element 2 through a through conductor (not shown), and the ground electrode 13 is connected to the ground terminal 14 on the other surface 2b of the piezoelectric element 2 through a through conductor (not shown). Connected to. As the material of the ceramic insulating layer 12, a ceramic material such as barium titanate or lead zirconate titanate is used. As materials for the internal electrode 10, the ground electrode 13, the power supply terminal 11, and the ground terminal 14, a metal material such as nickel, silver, tungsten, bell, or an alloy thereof is used.
In such a configuration, when a voltage is applied from the outside to the power supply terminal 11 and the ground terminal 14 of the piezoelectric element 2 and the piezoelectric element 2 vibrates, a frictional force is generated between the friction member 4 and the driven body 5, The drive body 5 will move.

Example 1
Next, a manufacturing method to which the present invention is applied will be described with reference to FIGS.
(1) a ceramic green sheet laminated body formation step _PbO, kneaded with an organic solvent and binder material powder consisting of TiO _2, ZrO 2. This is formed into a sheet shape to produce a plurality of ceramic green sheets. The thickness of the ceramic green sheet is formed such that the thickness of the ceramic insulating layer after firing is, for example, 50 to 200 μm.
Next, a through-hole is formed in the ceramic green sheet as necessary, and the through-hole is filled with a conductive paste for a through-conductor that becomes a through-conductor, and a conductor that becomes an internal electrode or a ground electrode on one main surface of the ceramic green sheet A layer is deposited. In addition, a conductor layer serving as a power supply terminal or a ground terminal is deposited on one main surface of the ceramic green sheet disposed in the uppermost layer when laminated.
The ceramic green sheets thus formed are laminated to produce a ceramic green sheet laminate 16 in which a plurality of pre-fired piezoelectric element regions 15 shown in FIG. 2 are arranged vertically and horizontally.
(2) Recess Forming Step Then, as shown in FIG. 3, the one surface 16 a of the ceramic green sheet laminate 16 is ground to form the recess 3 in the width direction of the piezoelectric element region 15 before firing. This grinding is performed by rotating the dicing saw 9 whose tip cross-sectional shape is an arc shape at high speed. Thus, since the recessed part 3 is formed by grinding the outer surface of the ceramic green sheet laminate 16 before deformed, the displacement of the recessed part 3 and the conductor layer that becomes the internal electrode 10 after firing can be suppressed. In addition, it is possible to prevent the occurrence of chipping and cracking, which are problems when processing the ceramic fired body. Further, the grinding speed can be improved and the dicing saw 9 can be prevented from being damaged or worn, so that the processing time can be shortened and the processing cost can be reduced.
(3) Individualization and firing step The ceramic green sheet laminate 16 formed with the recesses 3 is cut along the boundary line 18 to be individualized. The separated unfired piezoelectric element 19 is fired at a temperature of 1000 to 1300 ° C. to form the piezoelectric element 2. Due to the shrinkage of the unfired piezoelectric element 19 due to this firing, the conductor layer and the recess 3 that become the internal electrode 10 also shrink. However, since the shrinkage rate of the conductor layer and the recess 3 is the same, The position does not shift.
(4) Polarization / cutting / inspection step The piezoelectric element 2 is subjected to polarization processing by a known method in order to align the polarity of the piezoelectric material. Finally, the friction member 4 is bonded and fixed to the recess 3 to complete the piezoelectric actuator 1.

(Example 2)
This example is similar to Example 1 up to the ceramic green sheet laminate forming step and the recess forming step. However, after firing the ceramic green sheet laminate 16 in which the recesses 3 are formed, individual piezoelectric elements are separated into individual pieces. This is different from the first embodiment.
In this case, the ceramic green sheet laminate 16 in which the recesses 3 are formed is fired at a firing temperature of 1000 to 1300 ° C., and a fired ceramic parent substrate in which a plurality of piezoelectric element regions 20 as shown in FIG. 21 is formed. Next, in order to make the polarities of the piezoelectric materials uniform, a polarization process is performed by a known method.
Thereafter, the fired ceramic parent substrate 21 is cut along the boundary line 22 to be separated into individual piezoelectric elements 2. Finally, the friction member 4 is fixed to the recess 3 of the piezoelectric element 2 with an adhesive to complete the piezoelectric actuator 1.
Also in this embodiment, the outer surface of the ceramic green sheet laminate 16 before deforming the deformed shape is still ground to form the recess 3, so that the position of the recess 3 and the conductor layer that becomes the internal electrode 10 after firing is shifted. Can be suppressed.

DESCRIPTION OF SYMBOLS 1 Piezoelectric actuator 2 Piezoelectric element 2a 1 surface 2b Other surface 3 Concave part 4 Friction member 5 Driven body 9 Dicing saw 10 Internal electrode 11 Power supply terminal 12 Ceramic insulating layer 13 Ground electrode 14 Ground terminal 15 Piezoelectric element area | region 16 before firing Laminate 16a 1 side 18 boundary line 19 unfired piezoelectric element 20 piezoelectric element region 21 fired ceramic parent substrate 22 boundary line

Claims (1)

A method of manufacturing a piezoelectric actuator having a piezoelectric element that vibrates ultrasonically, and a friction member that transmits the ultrasonic vibration fixed to a recess formed on one surface of the piezoelectric element,
Forming a ceramic green sheet in which a plurality of pre-fired piezoelectric element regions to be rectangular piezoelectric elements after firing are arranged in a grid, and forming a conductor layer to be an internal electrode after firing in the pre-fired piezoelectric element regions; ,
Laminating a plurality of the ceramic green sheets to form a ceramic green sheet laminate;
A method of manufacturing a piezoelectric actuator comprising the step of grinding the outer surface of the ceramic green sheet laminate to form the recess in a direction corresponding to the width direction of the piezoelectric element region before firing.