JPH046999A - Manufacture of ultrasonic probe - Google Patents

Abstract

PURPOSE:To improve electric isolation state among components by forming a laminator comprising an acoustic matching layer, an electrode, a composite piezoelectric body of half-finished state, an electrode, and a packing layer and slitting the layer so as to form the arrangement of the pillar shaped piezoelectric body and component electrodes simultaneously. CONSTITUTION:A flat piezoelectric ceramic 1 is cut off unidirectionally at a prescribed interval, an organic material 3 is packed in gaps 2, and both faces are polished to form a composite piezoelectric body 4 in half-finished state. After silver electrodes 5, 6 are formed entirely on both faces of the piezoelectric body 4, an acoustic matching layer 7 is formed on the surface of the electrode 5, a packing member 8 is adhered on the surface of the electrode 6 to form an intermediate laminator. Then the laminator is cut off for all the layers simultaneously in a direction in crossing with the 1st cutting direction and a material 9 with low acoustic coupling is packed in produced gaps. Thus, the electric and acoustic isolation state among adjacent components is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method of manufacturing an ultrasonic probe using a composite piezoelectric material.

(Prior Art) Composite piezoelectric bodies have been developed that have a structure in which a columnar piezoelectric body made of an inorganic material is covered with an organic material. Due to its structure, such composite piezoelectric materials have two characteristics: a high electromechanical coupling coefficient that is unique to inorganic piezoelectric materials, and a low acoustic impedance that is unique to organic materials.
It is applied to various ultrasonic probes used in ultrasonic diagnostic equipment and the like.

FIG. 2 shows an example of such a composite piezoelectric body.

In the figure, 21 is a columnar piezoelectric body formed of an inorganic material such as piezoelectric ceramics, and 22 is an organic material surrounding the columnar piezoelectric body 21. This composite piezoelectric material is attracting particular attention because it can be easily manufactured by the following method (dicing method). That is, first, an inorganic piezoelectric material such as a piezoelectric ceramic plate is cut in the thickness direction at predetermined intervals in two intersecting directions to form fine columnar bodies 21 . Next, by filling the gap formed by the cutting with an organic material 22, the composite piezoelectric body shown in FIG. 2 is obtained.

In the conventional method of manufacturing an ultrasonic probe, the second
After forming a composite piezoelectric body having the structure shown in the figure, a plurality of electrodes are formed on the upper and lower surfaces of the composite piezoelectric body to be separated from each other. In that case, each electrode may include, for example] a row or a column of piezoelectric columns 2
1..., one electrode and each row or column of columnar piezoelectric bodies 21 covered with the electrode constitute a transducer element.

(Problem to be Solved by the Invention) After forming the composite piezoelectric body shown in FIG. 2 as described above, an ultrasonic probe having a large number of transducer elements is formed by forming a plurality of mutually separated electrodes. The manufacturing method has the following problems.

That is, when applied to the manufacture of an ultrasonic probe in which the pitch interval of individual transducer elements is very small, the positions of the columnar piezoelectric bodies and the electrodes formed on the top thereof do not match well, and the columnar piezoelectric bodies are adjacent to each other. It is easy to cause a situation where the electrode straddles the two electrodes.

When such a situation occurs, it becomes difficult to electrically isolate each element.

Further, since the electrodes formed by this method are simply separated structurally, there is also a drawback that acoustic separation between each element is insufficient.

The present invention has been made in view of the above problems, and its purpose is to provide a method that can improve electrical and acoustic isolation between each element when manufacturing an ultrasonic probe using a composite piezoelectric material. That's true.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the manufacturing method according to the present invention includes the following five steps.

In the first step, a flat inorganic piezoelectric material is cut in the thickness direction at predetermined intervals in only one direction to form gaps of a predetermined width.

In the second step, a semi-finished composite piezoelectric body is formed by filling the gap formed in the first step with an organic material. The composite piezoelectric body formed in this step has only one of the vertical and horizontal organic materials 22 filled in the completed composite piezoelectric body of FIG. This is why the composite piezoelectric body formed in this process is called "semi-finished." If necessary, the thickness is adjusted by polishing both the front and back surfaces of the semi-finished composite piezoelectric body.

In the third step, metal films for electrodes are laminated on both the front and back surfaces of this semi-finished composite piezoelectric body. The metal film formed here is not equally divided but has integrity.

In the fourth step, the laminate formed up to the third step is simultaneously cut in the thickness direction at a predetermined element interval in a direction crossing the cutting direction in the first step, and a predetermined width is set between each element. Gaps are formed to separate the individual elements from each other.

In the fifth step, by filling the gap formed in the fourth step with a material having low acoustic coupling,
At the same time as forming the completed composite piezoelectric body, acoustic isolation between each element is performed.

In addition, in the laminate formed up to the third step,
forming an acoustic matching layer on the surface after the step;
At least one of the steps of forming a backing layer on the back surface of the laminate may be performed, and the laminate thus formed may be subsequently processed in the fourth and subsequent steps.

In addition, in order to further improve the electrical and acoustic isolation between the respective elements, a material with low acoustic coupling that is filled in the fifth step is a material that is different from the organic material that is filled in the second step. A flexible material may also be used.

(Function) As described above, the composite piezoelectric body obtained at the end of the second step of the present invention is in a semi-finished state. Then, in the fourth step, the arrangement of each columnar piezoelectric body and each electrode constituting the composite piezoelectric body are simultaneously separated and formed. Therefore, the columnar piezoelectric bodies and electrodes constituting each element are formed in self-alignment, and their positions necessarily coincide.

In addition, in the gaps between each element formed in the fourth step,
In the fifth step, a material with low acoustic coupling is filled. As a result, a composite piezoelectric body similar to that shown in FIG. 2 is completed, and at the same time, since the material is also filled between the electrodes, acoustic isolation between each element is also achieved.

Furthermore, by employing the above method, the filler filled in the fifth step, that is, the material filled in each element gap, is a material with low acoustic coupling that is more effective in terms of acoustic isolation between each element. be able to freely choose.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIGS. 1A to 1E.

First, a flat piezoelectric ceramic 1 is cut in the thickness direction only in one direction at predetermined intervals, and gaps 2 of a predetermined width are cut.
(as shown in FIG. 1A).

The gap 2 thus formed is filled with an organic material 3 such as an epoxy resin, and the thickness is adjusted by polishing both the front and back surfaces to form a composite piezoelectric body 4 in a semi-finished state (FIG.
(Illustrated).

Next, silver electrodes 5.6 are formed over both the front and back surfaces of the semi-finished composite piezoelectric body (as shown in C in the figure). Also,
Here, electrodes are drawn out from positions corresponding to each transducer element. However, this electrode extraction is possible even after all steps are completed.

Next, an acoustic matching layer 7 made of epoxy resin or the like is formed on the surface of the upper electrode 5 (as shown in the figure). Further, a backing material 8 is adhered to the surface of the lower electrode 6.

In this way, an intermediate laminate consisting of acoustic matching layer 7/silver electrode 5/semi-finished composite piezoelectric material 4/silver electrode 6/backing material 8 is constructed.

Next, the laminate is simultaneously cut in the thickness direction at a predetermined element pitch in a direction intersecting (not necessarily orthogonal to) the first cutting direction of the piezoelectric ceramic, up to a part of the surface layer of the backing material layer. In some cases, the resulting gap is filled with a material 9 with low acoustic coupling (
(Illustrated in E of the same figure).

Here, the material 9 is desirably filled with an organic material that is more flexible than the organic material 3 constituting the composite 4.

A desired ultrasonic probe is manufactured in the manner described above.

In the method of the above embodiment, after forming a laminate having the structure of acoustic matching layer 7/electrode 5/semi-finished composite piezoelectric material 4/electrode 6/backing layer 8, this is layered over all layers to form a desired element. By cutting at intervals, the array of columnar piezoelectric bodies constituting the composite piezoelectric body and each element electrode are formed at the same time, and the positions of both can be easily matched. Therefore, the columnar piezoelectric body does not exist straddling the two electrodes as in the prior art, and the state of electrical isolation between each element of the ultrasonic probe can be improved.

Further, after the above-described elements are formed, the separated electrode gaps are also filled with a material having low acoustic coupling, so that the acoustic isolation between the elements of the ultrasonic probe is also improved.

Furthermore, the material filled in each element gap can be freely selected to be a material with low acoustic coupling that is more effective in terms of acoustic isolation between each element, resulting in reduced acoustic coupling and other acoustic isolation. The condition is further improved and the reliability of the function of the ultrasonic probe is ensured.

Note that, for example, in the case of a linear electronic scan probe or the like, it is not necessary to cut and separate the acoustic matching layer 7. In such a case, after forming the electrodes in the state shown in Figure C, first cut at each element pitch and fill the gaps with a material with low acoustic coupling, and then form the acoustic matching layer. do it. Alternatively, form an acoustic matching layer in the same state 1
7, cutting from the back surface at each element pitch (excluding the acoustic matching layer) and filling with a material with low acoustic coupling may be performed.

In addition, if the acoustic matching layer is unnecessary, the acoustic matching layer 7
The step of forming (D in the same figure) can be omitted.

〔Effect of the invention〕

As detailed above, the present invention is extremely effective in easily realizing electrical and acoustic isolation between adjacent elements in an ultrasound probe (mainly an array type ultrasound probe) that applies a composite piezoelectric material. This has the following effects.

[Brief explanation of drawings]

FIGS. 1A to 1E are explanatory diagrams showing an embodiment of the present invention along the manufacturing process, and FIG. 2 is a perspective view showing a composite piezoelectric body used in a conventional manufacturing method. DESCRIPTION OF SYMBOLS 1... Flat piezoelectric ceramic, 2... Gap formed by cutting the flat piezoelectric ceramic, 3... Organic material (for composite piezoelectric body composition), 4... Composite piezoelectric body in a semi-finished state , 5... Surface silver electrode, 6... Back surface silver electrode,
7... Acoustic matching layer, 8... Backing layer (material), 9
... Material with low acoustic coupling, 21 ... Column piezoelectric material, 22 ... Organic material (for composite piezoelectric material composition) Applicant's representative Patent attorney Takehiko Suzue Figure 2 Figure 1

Claims (3)

[Claims] (1) A first step of cutting a flat inorganic piezoelectric material in the thickness direction at predetermined intervals in only one direction to form gaps of a predetermined width, and applying an organic material to the gaps formed in the first step. a second step of forming a semi-finished composite piezoelectric body by filling; a third step of laminating an integral metal film for an electrode on both the front and back surfaces of the semi-finished composite piezoelectric body; and the third step. simultaneously cutting all layers of the laminate formed in the above steps in the thickness direction at a predetermined element interval in a direction crossing the cutting direction of the first step;
A fourth step of forming a gap of a predetermined width between each element to separate the individual elements from each other, and filling the gap formed in the fourth step with a material with low acoustic coupling to produce a finished composite. A fifth layer that forms a piezoelectric material and at the same time provides acoustic isolation between each element.
A method for manufacturing an ultrasonic probe, comprising the steps of: (2) Between the third step and the fourth step, a step of forming an acoustic matching layer on the surface of the laminate obtained in the third step and/or a step of forming a backing layer on the back surface of the laminate. The method for manufacturing an ultrasonic probe according to claim 1, comprising: (3) Manufacturing the ultrasonic probe according to claim 1 or 2, wherein the material with low acoustic coupling filled in the fifth step is a flexible material different from the organic material filled in the second step. Method.