JPH0750803B2 - Method for manufacturing composite piezoelectric body - Google Patents

Description

The present invention relates to a method for manufacturing a composite piezoelectric body.

<Prior Art> Ferroelectric ceramic particles (powder) such as lead zirconate titanate (PZT) and lead titanate (PT) are dispersed and mixed in a polymer material such as synthetic resin or synthetic rubber to have a predetermined shape. It is known that a composite piezoelectric body is formed by molding, and further, electrodes are formed on the upper and lower surfaces and polarized to form a composite piezoelectric body.

By the way, in such a composite piezoelectric body, as shown in FIG. 6, each ceramic particle b is distributed independently of each other in a polymer matrix a, and there is no polymer between the upper and lower electrodes c, c. It is continuous. Therefore, during the polarization treatment, the polarization voltage is not sufficiently applied to the ceramic particles b, and the desired performance cannot be obtained. Further, if the polarization voltage is excessively increased to obtain the desired performance, dielectric breakdown will occur.

Therefore, as shown in FIG. 7, a holding sheet d having a large number of through holes e formed in advance from a synthetic rubber or synthetic resin material.
A large number of piezoelectric particles f formed of a ferroelectric ceramic and formed in a columnar shape such as a cylindrical shape or a rectangular shape are embedded in the through holes e, and the piezoelectric particles f are formed on the front and back surfaces of the holding sheet. A composite piezoelectric body was proposed in which the front surface and the back surface of the holding sheet were covered with electrodes g, g while exposing the.

In this structure, since the piezoelectric particles f are continuous between the electrodes g, the polarization voltage can be directly applied, and the above-mentioned defects can be eliminated.

On the other hand, in such a configuration, the piezoelectric particles f are not tightly embedded in the through holes e of the holding sheet d due to variations in the shape of the piezoelectric particles f, irregular embedding state, etc. There was a gap inside and it sometimes fell off.

It is an object of the present invention to provide a manufacturing method capable of removing the defects of the piezoelectric composite material having such a structure.

<Means for Solving Problems> The present invention is a method for manufacturing a composite piezoelectric body including the following steps.

A) An alignment plate having a large number of through holes arranged in line is arranged on a substrate having an adhesive layer formed on the upper surface thereof.

B) After the columnar piezoelectric particles are embedded in the through holes of the alignment plate, the alignment plate is removed and only the piezoelectric particles are held on the substrate.

C) A substrate is covered in the molding frame with the piezoelectric particles inside, and a molding chamber having a depth corresponding to the thickness of the alignment plate is formed by the substrate and the molding frame.

D) Inject the pasty polymer into the molding chamber.

E) A plate-shaped molded body formed by consolidating a polymer,
Separate from the substrate and molding frame.

F) Electrodes are formed on the upper and lower surfaces of the plate-shaped compact, and a voltage is applied between the electrodes to polarize the piezoelectric particles of the plate-shaped compact in the thickness direction.

<Function> Since the piezoelectric particles are held in an aligned state and then the polymer is injected into the lattice-shaped voids formed around the piezoelectric particles, the piezoelectric particles are retained in the holding sheet irrespective of variations in the shape of each piezoelectric particle. Will be buried integrally and closely.

<Example> The method of the present invention is preferably carried out based on the following steps.

First Step In FIG. 1, reference numeral 1 denotes a substrate having an adhesive tape 2 arranged on one side thereof, on which an alignment plate 3 is mounted and joined by the adhesive tape 2. The adhesive tape 2 is an example of an adhesive layer, and the adhesive layer may be directly formed on the substrate 1 by coating.

Rectangular through holes 4 are arranged in the alignment plate 3 vertically and horizontally.

Then, each through hole 4 is filled with a rectangular columnar piezoelectric particle 5 of about 1 mm square. The shape of the through hole 4 may be various shapes such as a cylindrical shape corresponding to the shape of the embedded piezoelectric particles 5.

The piezoelectric particles 5 are formed by press-molding powder particles, and Japanese Patent Application No. 61-2041 of the same applicant as the present applicant.
By the means disclosed in No. 99, the large single crystal particles formed can be used as they are.

That is, based on the composition formula Pb _{1 + x} TiO _{3 + x} (where 0 <x), TiO ₂ and PbO are mixed at a predetermined ratio, and this is mixed at 1150 ° C to 1
It was confirmed that the lead titanate particles obtained by heating and calcining in the range of 300 ° C. had a large particle size and had a cubic shape with developed c-axis. This particle size is about 30 μm to 1.5 mm. Here, x represents the excess rate of lead oxide PbO.

Therefore, the lead titanate particles formed by such means can be used as the piezoelectric particles 5 as they are.

Second Step Next, the alignment plate 3 is removed from the substrate 1 as shown in FIG. After the removal, the piezoelectric particles 5 are left on the upper surface of the substrate 1, and the bonding force of the adhesive tape 2 causes the alignment plate 3 to move.
Based on the arrangement of the through-holes 4 in FIG. That is, the lattice-shaped voids are formed around the piezoelectric particles 5.

The third step 6 is a rectangular dish-shaped molding frame having a depth equivalent to the thickness of the alignment plate 3 and having an internal space 7 of the same plane shape, and one side edge thereof has the internal space. A resin supply port 8 communicating with the inside of 7 is formed. Then, the substrate 1 is turned over and adhered to the upper surface of the molding frame 6, and the piezoelectric particles 5
Is stored in the internal space 7. In such a state,
A closed molding chamber 9 is formed between the molding frame 6 and the substrate 1.

In the above configuration, the peripheral edge of the molding chamber 9 is constituted by the peripheral brim of the molding frame 6, but the shape of the substrate 1 may be dish-shaped.

Fourth Step A paste-like polymer 10 such as synthetic rubber or synthetic resin material is injected from the hopper 11 into the molding chamber 9 through the resin supply port 8 to fill the lattice-shaped voids around the piezoelectric particles 5.

-Fifth step The substrate 1 and the molding frame 6 are separated, and the plate-shaped molded body 11 formed by consolidating the polymer 10 is taken out. And this molded body
11 is a holding sheet 12 made of synthetic rubber or synthetic resin material
In addition, the piezoelectric particles 5 are embedded in an array.

-Sixth step: Electrodes 13 and 13 are formed on the upper and lower surfaces of the plate-shaped compact 11, and a voltage is applied between the electrodes 13 and 13 to polarize the piezoelectric particles 5 of the plate-shaped compact 11 in the thickness direction. .

The electrodes 13 and 13 can be used as they are as input / output electrodes.

<Effects of the Invention> As described above, the present invention provides a composite piezoelectric body in which piezoelectric particles 5 are embedded in an array in a holding sheet 12 made of synthetic rubber or synthetic resin. Since it is formed by injecting a polymer into the peripheral part later, the piezoelectric particles 5 can be embedded tightly and integrally in the holding sheet 12, and the holding is strong, which is an excellent effect. There is.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 5 show respective manufacturing steps of a preferred embodiment of the method of the present invention, and FIG. 1 shows a state in which an alignment plate 3 is held on a substrate 1. In perspective view and FIG. 2, the alignment plate 3 is removed,
Fig. 3 is a perspective view showing a state where the piezoelectric particles 5 are held on the substrate 1, Fig. 3 is a vertical sectional side view showing the molding means, Fig. 4 is a perspective view of the molded body 11, and Fig. 5 shows polarization treatment of the molded body 11. It is a vertical side view. Further, FIGS. 6 and 7 are longitudinal side views showing the structure of a composite piezoelectric body having a conventional structure, respectively. 1; Substrate, 2; Adhesive tape, 3; Alignment plate, 4; Through hole, 5; Piezoelectric particles, 6; Molding frame, 7; Internal space, 8; Resin supply port, 9; Molding chamber, 10; Polymer, 11 Molded body, 12; holding sheet, 13,13;
electrode

Claims (1)

[Claims] 1. A method of manufacturing a composite piezoelectric body comprising the following steps. A) An alignment plate having a large number of through holes arranged in line is arranged on a substrate having an adhesive layer formed on the upper surface thereof. B) After the columnar piezoelectric particles are embedded in the through holes of the alignment plate, the alignment plate is removed and only the piezoelectric particles are held on the substrate. C) A substrate is covered in the molding frame with the piezoelectric particles inside, and a molding chamber having a depth corresponding to the thickness of the alignment plate is formed by the substrate and the molding frame. D) Inject the pasty polymer into the molding chamber. E) A plate-shaped molded body formed by consolidating a polymer,
Separate from the substrate and molding frame. F) Electrodes are formed on the upper and lower surfaces of the plate-shaped compact, and a voltage is applied between the electrodes to polarize the piezoelectric particles of the plate-shaped compact in the thickness direction.