JPH01244682A - Manufacture of compound piezoelectric body - Google Patents

Abstract

PURPOSE:To enable easy and efficient manufacture of a compound piezoelectric body of high performance and high precision wherein electro-mechanical coupling-coefficient is large and acoustic impedance is small, by forming a piezoelectric board as a pillar type piezoelectric members of minute dimension, and retaining the pillar type piezoelectric members in an integrated body with an organic body compound of organic material. CONSTITUTION:On the upper surface of a PZT plate 10 of t0 thick, a plurality of trenches 11 intersecting each other in the form of a mesh are formed, whose width and depth are (w) and d1 (d1<t0), respectively. The pitch of row is (p), and that of column is 2p. Thus, a plurality of pillar type piezoelectric members 12 are formed. The trenches 11 are filled with resin, which is hardened and processed in a specified thickness (t). Electrode layers 13 composed of conductive metal material are formed on the surface and the rear of the PZT plate 10. Organic bodies 14 are formed so as to retain a plurality of piezoelectric members 12. In the intermediate part of the organic bodies 14 arranged with pitches 2p, out of the above organic bodies, a plurality of trenches 15 (w) in width and d2(d2<t+t1) in depth are formed with pitches 2p, and a group form arranged compound piezoelectric body 16 composed of a plurality of piezoelectric members 12 are formed. By the processing to obtain a dimension of T+t1, from a substrate surface, the organic bodies 14 to retain the group form arranged compound piezoelectric body 16 is exposed on the processed surface. After the processed surface is washed, an electrode layer 17 of t2 thick is stuck thereon.

Description

[Detailed description of the invention] [Industrial application field] The present invention is a composite piezoelectric material commonly called 1-3 type.

In other words, it relates to a method for producing a composite piezoelectric material having a structure in which a large number of piezoelectric materials made of one-dimensionally connected ceramics are embedded in a three-dimensionally connected organic material, and has a particularly high electromechanical coupling coefficient and low acoustic impedance. The present invention relates to a method for manufacturing a composite piezoelectric body.

(Prior Art) Conventionally, in the medical field, ultrasound diagnostic equipment has been effectively used to display and observe biological tissues as tomographic images.Such diagnostic equipment can generate tomographic images in real time by transmitting and receiving ultrasonic waves. Ultrasonic diagnosis has become rapidly popular in recent years because it can be used for diagnosis and is extremely safe.However, as ultrasonic diagnosis requires considerable skill, sensitivity - 2 resolution, etc. It is desired to improve the diagnostic function by improving the performance of A low value close to that of a living body is desirable.

The above piezoelectric materials include inorganic piezoelectric materials such as lead zirconate titanate ceramics (hereinafter referred to as PZT) and lead titanate ceramics (hereinafter referred to as PTO), as well as polyvinylidene fluoride (hereinafter referred to as PVF). ) and other organic piezoelectric materials.

However, among the above-mentioned materials, PZT and PTO have extremely high electromechanical coupling coefficients, but have the disadvantage that they also have high acoustic impedance. On the other hand, PVF has a low acoustic impedance, but also has a low electromechanical coupling coefficient, and there is no material that satisfies both characteristic values at the same time.

Recently, composite piezoelectric bodies have been proposed that are made by combining the above-mentioned inorganic piezoelectric materials with organic materials. An ultrasonic probe for medical use is being considered as an ultrasonic probe for medical use.

FIG. 2(a) (bl) is a diagram illustrating means for manufacturing the above-mentioned conventional composite piezoelectric bodies. First, what is shown in FIG. 2 (tal) is a piezoelectric plate 1 made of, for example, PZT.

A plurality of grooves 3 are formed in a mesh pattern to a depth halfway in the thickness direction via a rotating blade 2, and after filling and hardening resin (not shown) in these grooves 3, cutting and polishing to an appropriate thickness is performed. A composite piezoelectric material is obtained by combining the two.

In addition, in the case shown in FIG. 2 fbl, a thin piezoelectric plate l made of the same material as described above is temporarily adhered to a smooth polished substrate 4, and then cut into a mesh shape using a cutting tool such as a cutting tool. and completely cut in the thickness direction to form a plurality of columnar piezoelectric bodies 5, and a plurality of grooves 3 formed by cutting.
A composite piezoelectric body is obtained by filling and hardening the resin 6 inside the body and then peeling it off from the substrate 4.

[Problem to be solved by the invention]

In the conventional method described above, first, in the method shown in FIG. However, there is a problem in that it is almost impossible to cut into thin pieces.

Further, reducing the width of the groove 3 requires reducing the width of the cutting tool or the cutting blade, which naturally has a limit in terms of strength. - In the case shown in Fig. 2 (bl), the columnar piezoelectric body 5 formed by cutting not only collapses or peels off, but also causes defects such as chips.Also, peeling after resin filling occurs. There are problems such as difficulty in

In addition, when the above-mentioned composite piezoelectric material is used as a component of a medical ultrasonic probe, for example, the culm image quality is high because the number of arrays constituting a unit element is large.

Of course, it is possible to improve performance.

In such a composite piezoelectric body, the columnar piezoelectric body has extremely small dimensions, and the effective displacement portion due to the width dimension of the cut groove becomes extremely small. Furthermore, since the electrodes provided on the front and back surfaces of these columnar piezoelectric bodies are generally made by vapor deposition,
Soldering cannot be used to attach lead wires for signal extraction, and adhesives or the like must be used. Therefore, attaching the lead wires is extremely difficult.

There is a problem in that the reliability after installation is lowered. Furthermore, in the case where the above electrodes are provided only by masking means, it is physically impossible to significantly reduce the width dimension of the masking material, so the area of the effective displacement portion of the columnar piezoelectric body decreases and There is a problem in that the inherent characteristics of piezoelectric materials having a mechanical coupling coefficient cannot be utilized.

The present invention solves the problems existing in the above-mentioned prior art, and provides a high-performance, high-precision composite piezoelectric material with a high electromechanical coupling coefficient and low acoustic impedance.

The purpose is to provide a method that can be manufactured easily and efficiently.

[Means to solve the problem]

One aspect of the present invention is to solve the problems existing in the conventional teeth described above.

A. In a method for manufacturing a composite piezoelectric material having a thickness T in which a plurality of piezoelectric materials are arranged at pitches p+, p1, and p2 in the perpendicular direction via an organic material.

B. Thickness [. 1 width w, (w, <pl), W2 on the top surface of a piezoelectric plate made of a piezoelectric material (to > t > T)
(wx<pz), depth dl (dt<to), and one side is pl or I'2, and the other is pl or I'2,
The other one is bored at a pitch of 2pz or 2p+ to form a plurality of piezoelectric bodies.

C0 The plurality of grooves are filled with an organic material and solidified to form an organic material that holds the piezoelectric material.

D. Processing and forming the piezoelectric plate to a predetermined thickness from its upper surface.

E. Form an electrode layer on both the front and back surfaces of the piezoelectric plate with a thickness of .

F, 1 width w or Wt + depth d2 (
d2 < t + L1), and 7 grooves 2 pz
Alternatively, a 2p+ hole is formed to form a group-aligned composite piezoelectric body consisting of a plurality of piezoelectric bodies.

G. Filling and solidifying an organic material in the plurality of grooves to form an organic body that holds the group-aligned composite piezoelectric material.

H. Process and mold this cluster-aligned composite piezoelectric material to a predetermined thickness T from the upper surface of the organism.

J. An electrode layer 17st2 is formed on this processed and formed surface.

This technical method was adopted.

[Effect]

With the above configuration, it is possible to form a piezoelectric body plate made of a piezoelectric material into a columnar piezoelectric body of minute dimensions, and to obtain a composite piezoelectric body in which these columnar piezoelectric bodies are integrally supported by an organic body made of an organic material. It is.

〔Example〕

Figures 1 (tal) to (dl) are enlarged perspective views showing the main parts of the manufacturing process of the composite piezoelectric material in the embodiments of the present invention. First, a PZT plate IO of thickness Lo as shown in Figure 1 (al) is #! Prepared. In this case, the thickness to of the PZT plate is made slightly larger than the thickness t when it is made into a composite piezoelectric material. Next, this PZT plate 1 sheet metal 0 smooth substrate (not shown) Temporarily adhered to the top with wax or other heat-softening resin, as shown in Figure 1 (
As shown in b), the width W and the depth dl are set on the 0th side of the PZT plate 1 sheet metal.
(dl < Lo), a plurality of grooves 11 intersecting in a mesh shape are bored at a pitch of p on one side and 2p on the other side,
A plurality of columnar piezoelectric bodies 12 are formed. Since the plurality of piezoelectric bodies 12 are connected together at the bottom of the PZT plate IO, they will not collapse or peel off even if the groove 11 is bored. Next, a polyurethane-based or epoxy-based resin is filled and cured in the groove It to form an organic body (not shown) that holds the piezoelectric body 12, and then heated to melt the wax and form a PZT plate. Peel off the IO,
It is turned over and temporarily bonded onto the substrate again in the same manner as described above, and processed and formed to a predetermined thickness t. Note that the depth d of the groove ll.

is preferably selected so that d>t.

Thickness

As shown in FIG. 1 (cl), an electrode layer 13 made of a conductive metal material such as Ni is formed by, for example, metal plating, and then temporarily placed on a substrate (not shown) via wax in the same manner as described above. Next, among the organic bodies 14 formed to hold a plurality of piezoelectric bodies 12, a 9-width W, depth d, (d, <t
+t, ) are drilled at a pitch of 2p,
A group-aligned composite piezoelectric body 16 consisting of a plurality of piezoelectric bodies 12 is formed. Note that the groove 15 is filled with resin and cured in the same manner as described above to fill the organic body (
(not shown). After the resin has hardened, the pzT temporary 10 is peeled off from the substrate, turned over once, and then affixed to the substrate again. Next, T tent from the board surface (however, Tkut,'r+t,<a,)
The organic body 14 holding the group-aligned composite piezoelectric body 16 appears on the machined surface. After cleaning the processed surface, an electrode layer 17 with a thickness of tz is formed as shown in FIG.
By depositing the above, it is possible to obtain a composite piezoelectric body containing a micro-column-shaped piezoelectric body 12 having upper and lower electrode layers. In this case, the electrode layer 17 forms a common electrode for the plurality of micro-column-shaped piezoelectric bodies 12.

By the above manufacturing method, 80mm x 80mm, thickness 1mm
By providing a groove of 35 to 40 μm on the PZT plate,
A composite piezoelectric material having a thickness of 0.4 mm was obtained in which minute columnar piezoelectric materials each having a size of 80 μm×80 μm were arranged at a pitch of 110 μm in the perpendicular direction. Note that the thickness of the N+ electrode layer was 2 μm on each of the front and back surfaces. In addition, the electromechanical coupling coefficient and acoustic impedance Z1 of the composite piezoelectric material described above are as shown in the table, and although there are slight differences depending on the organic material forming the organic body that holds the piezoelectric material, each is compared with the conventional one. It shows a much better value.

In this example, the case where the piezoelectric material is pz"r is described, but piezoelectric materials other than PZT can be used. Also, in order to form an organic body for supporting the piezoelectric material, a piezoelectric material plate is used. The grooves intersecting each other in the form of a mesh to be provided may have different widths w, , wz, and the piezoelectric bodies may be arranged at different pitches p+, pz in the orthogonal direction.

Furthermore, the intersecting angle of the mesh may be any angle other than a right angle. Furthermore, even if the electrode layer in which the conductive portion for causing the piezoelectric body to perform the piezoelectric action is formed of a conductive metal material other than Ni, the same effect will be obtained. Although an example has been shown in which one of the electrode layers is formed as a common electrode, a structure in which the two front and back surfaces are each divided may also be used. In addition, multiple piezoelectric bodies are
Not only are they arranged at a pitch of l, pt, but also
Even with the structure shown in Figure fbl, the same effect can be expected as long as the dimension d2 in Figure 1 (C1) is sufficiently large. I described the case where .

It may also be formed by silver paste coating or other forming means.

〔Effect of the invention〕

Since the present invention has the structure and operation as described above,
The following effects can be expected.

(1) In order to form a piezoelectric plate with a thickness close to the final wall thickness without cutting into thin plates from a block-shaped piezoelectric plate, the organic body that holds the micro-column-shaped piezoelectric body is For the organic materials that make up the product.

For example, it is highly flexible and has low acoustic impedance.
Material A can be freely selected, and a composite piezoelectric body with high performance and high precision can be manufactured.

(2) When forming multiple micro-column-shaped piezoelectric bodies from a piezoelectric plate, the piezoelectric bodies do not collapse or peel off, and there are no defects such as cracks, which increases the reliability of the composite piezoelectric body. can be significantly improved, and the manufacturing yield is high.

(3) Since the piezoelectric plate used as the material is relatively thin, the width of the grooves drilled in the piezoelectric plate to form the organic body can be made extremely small, resulting in high yield and high Efficiency production is possible.

(4) Since the electrode layers formed on both the front and back sides of the piezoelectric body are formed by plating, there is no erosion by solder unlike in conventional vapor-deposited films, and lead wires can be attached easily and reliably. Become.

[Brief explanation of the drawing]

FIG. 1 (al to (di) are enlarged perspective views showing the main parts of the manufacturing process of the composite piezoelectric material in the embodiments of the present invention, and FIG. 2 t
a+ (b) are diagrams each illustrating means for manufacturing a conventional composite piezoelectric body. tt, ts: groove, 12: piezoelectric material, 13. I7: electrode layer,
14: Organism.

Claims (7)

[Claims] (1) In a method for manufacturing a composite piezoelectric material having a thickness T in which a plurality of piezoelectric materials are arranged at pitches p_1 and p_2 in the perpendicular direction via an organic material, a piezoelectric material having a thickness t_0 (t_0>t>T) A width w_1 (w_1
<p_1), w_2(w_2<p_2), depth d_1(
d_1<t_0), which intersects in a mesh pattern,
A plurality of piezoelectric bodies are formed by drilling one groove at a pitch of p_1 or p_2 and the other groove at a pitch of 2p_2 or 2p_1, and the plurality of grooves are filled with an organic material and solidified to form an organic body that holds the piezoelectric body. Then, the piezoelectric plate was processed and formed to have a predetermined thickness t from its upper surface, and electrode layers having a thickness of t_1 were formed on both the front and back surfaces of the piezoelectric plate, and the electrode layers were arranged on the piezoelectric plate at a pitch of 2p_2 or 2p_1. In the middle of the organism,
Width w_1 or w_2, depth d_2 (d_2, t+t
_1) A plurality of grooves with a pitch of 2p_2 or 2p_
1 to form a group-aligned composite piezoelectric body made up of a plurality of piezoelectric bodies, and fill and solidify an organic material in the plurality of grooves to form an organic body that holds the group-aligned composite piezoelectric body. death,
A method for manufacturing a composite piezoelectric material, characterized in that the group-aligned composite piezoelectric material is processed and formed to a predetermined thickness T from the upper surface of the organic body, and an electrode layer having a thickness t_2 is formed on this processed and formed surface. (2) The method for manufacturing a composite piezoelectric body according to claim 1, wherein the material constituting the piezoelectric body is a lead zirconate titanate ceramic or a lead titanate ceramic. (3) The method for manufacturing a composite piezoelectric body according to claim 1 or 2, wherein the organic material constituting the organic body is a polyurethane resin or an epoxy resin. (4) The method for manufacturing a composite piezoelectric material according to any one of claims 1 to 3, wherein the intersecting angle of the grooves is a right angle. (5) The method for manufacturing a composite piezoelectric body according to any one of claims 1 to 4, wherein the arrangement pitch of the piezoelectric bodies is P_1=P_2. (6) The method for manufacturing a composite piezoelectric material according to any one of claims 1 to 5, wherein the width of the groove forming the organic body is w_1=w_2. (7) Width w_1 and/or w of the groove forming the organism
The method for manufacturing a composite piezoelectric material according to any one of claims 1 to 6, wherein _2 is 75 μm or less.