JPS61754A - Laminated high polymer piezo-electric type ultrasonic probe - Google Patents

Abstract

PURPOSE:To obtain a laminated high polymer piezo-electric type ultrasonic probe with a higher resolution and the like, by providing a groove section on one side of a high polymer piezo-electric body having electrodes on both sides thereof along the crease thereof to position the electrode patterns on both sides thereof accurately with an easier bending. CONSTITUTION:A strips-shaped electrode 15 is provided on one side of a high polymer based piezo-electric body 14 made of polyvinylidene fluoride (PVF2), a copolymer of the polyvinylidene fluoride and ethylene trifluoride and a groove 17 is provided on one side thereof with a common electrode 16 formed on the other side thereof, for example, at a part along the crease on the electrode 16 side thereof to obtain a piezo-electric body 14. The piezo-electric body 14 thus obtained is bent and laminated at the groove 17, which then, is covered with a conductive paste 18 to eliminate electric separation of the common electrode 16. Otherwise, a connection metal 23 is applied in the groove 17 by evaporation or the like to obtain a laminated piezo-electric body 13. Then, the electrode 16 is connected to a copper electrode 12 on a support 11 while leads 19a and 19b are connected respectively to the electrode 15 and the copper electrode 12, then, they are entirely covered with a polyester film 20 and an epoxy resin 21 is injected to solidify. Thus, a highly reliable ultrasonic probe is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a laminated polymer piezoelectric ultrasonic probe formed by folding and laminating a polymer piezoelectric material a plurality of times.

[Technical background of the invention and its problems]

BACKGROUND ART Conventionally, linear array type ultrasonic probes used in linear electronic scanning systems have been array type ultrasonic probes in which a ceramic piezoelectric material such as lead titanate or titanium/lead zirconate is cut into strips. However, such ceramic piezoelectric bodies are hard and brittle, and are prone to chipping and cracking when cut and divided, making it difficult to precisely form many strip-shaped itts, and from the viewpoint of cost 1. There were also many problems.

On the other hand, polyvinylidene fluoride (hereinafter referred to as PVF2)
Fluorine-containing polymers such as polyvinylidene fluoride-ethylene trifluoride copolymer (hereinafter abbreviated as PVF2 and TrFE) or other organic synthetic polymers are polarized under high humidity and high electric field. It is known that by doing so, it exhibits piezoelectricity and pyroelectricity. Further, in recent years, development of ultrasonic probes using the thickness vibration of the piezoelectric polymer has been actively conducted. These polymer piezoelectric materials have a specific acoustic impedance close to that of a living body and a small elastic modulus, so when applying a polymer piezoelectric material to a linear array type ultrasound probe, it is best to use ceramic piezoelectric materials as an example. In contrast, it is said that it is not necessarily necessary to cut and separate the polymer piezoelectric material itself into strips.

However, the dielectric constant of polymer piezoelectric materials is generally about 10 orders of magnitude, which is significantly lower than that of ceramic piezoelectric materials, and furthermore, because the drive element area of linear array ultrasonic probes is small, the electrical impedance is significantly lower. Usually, electrical matching with a 50Ω power supply (emitting/receiving circuit) is poor, and the loss of the ultrasonic probe is significantly reduced.

For this reason, it has been proposed to appropriately laminate a plurality of polymeric piezoelectric materials to make the thickness substantially equivalent to that of a thick film and to lower the electrical impedance. As an example, as shown in FIG. 4, a plurality of polymer piezoelectric materials 3 each having a strip-shaped electrode 1 and a common electrode 2 formed on both sides are prepared.
Fa
A laminated polymer whose electrical impedance is lowered by connecting identical electrodes that are layered and facing each other (for example, the first layer and the second layer are strip-shaped electrodes 1 to each other) via solder or conductive adhesive 4. Piezoelectric ultrasonic probes are known. For example, if the electrical impedance of a single layer with a thickness having a resonant frequency f is Zo, then in the laminated structure shown in Figure 4, Z=Zo/n2 (where n1. is the number of laminated layers).
It is expressed as 1/4 for two-layer laminate and 1/9 for three-layer laminate.
This improves the electrical impedance and electrical matching with the power supply. However, in the 11* structure shown in FIG. 4, the leads Ii+5a,
When taking out the wire 5b and connecting it, it is very difficult in practical terms.

Therefore, as shown in Fig. 5, a single continuous polymeric piezoelectric material 3- is appropriately folded to form a laminate with a desired thickness, thereby reducing electrical impedance and making it easier to take out lead wires. A child is proposed. Although such an ultrasonic probe is simple and expected to have great practical effects, it has the following problems.

That is, when folding one continuous polymeric piezoelectric material 3', it is difficult to align the strip-shaped electrodes 1 with each other accurately;
The electrode 1 shifts vertically.

If such a shift occurs, a difference in electrical impedance of the driving elements may occur or a short circuit between the driving elements may occur. This problem becomes more noticeable as the number of folds (the number of stacked layers) of the polymer piezoelectric material 3- increases.

[Purpose of the invention]

The present invention provides a laminated polymer piezoelectric superstructure that allows a polymer piezoelectric material to be easily folded, and furthermore, when the polymer piezoelectric material is folded, electrode shape patterns formed on both sides of the polymer piezoelectric material can be easily and accurately aligned. The aim is to provide a sonic probe.

[Summary of the Invention] The present invention provides a laminated polymer piezoelectric ultrasonic probe formed by folding a polymer piezoelectric material having electrodes formed on both sides to form at least two or more W4 layers. It is characterized by providing a groove on one side along the body fold. According to the present invention, as described above, it is possible to easily fold the polymeric piezoelectric material, and when folding the polymeric piezoelectric material, it is possible to easily and accurately shape the electrode shape pattern U formed on both surfaces of the polymeric piezoelectric material. It is possible to obtain a laminated polymer piezoelectric ultrasonic probe that can perform

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 and 2.

Reference numeral 11 in the figure is a support made of, for example, acrylic resin, and on the support 11 is fixed a copper plate 12 having a thickness of, for example, 2.0 μm and serving both as an acoustic reflection plate and an electrode portion of the common electrode. On this copper plate 12, a laminated piezoelectric body 13 which is folded once is arranged. This laminated piezoelectric unit is PVF2
A piezoelectric body 14 is provided. A silver strip-shaped electrode 15 is formed on one surface of the piezoelectric body 14, and a silver common electrode 16 is formed on the other surface. A V-shaped groove 17 is provided on the common 1ff 116 side of the PVF2 piezoelectric body 14 so as to be orthogonal to the length direction of the strip-shaped electrode 15. Then, the piezoelectric body 14 is fixed in the V-shaped groove 17 so that the groove 17 becomes the outer side, and the strip-shaped N pole 15
The laminated piezoelectric body 13 is constructed by folding and stacking the piezoelectric elements once so that they face each other. By placing the laminated piezoelectric body LL on the copper plate 12, the common electrode 16 of the laminated piezoelectric body 13 comes into contact with the copper plate 12. Further, the groove portion 17 is coated with, for example, a conductive paste 18, and the common electrodes 16 separated by the formation of the V-shaped groove portion 17 are interconnected.

The laminated piezoelectric body unit is manufactured by the following method.

First, silver layers with a thickness of about 1 μm are deposited on both sides of a uniaxially stretched PVF2 film with a thickness of 50 μm, for example, by vacuum evaporation method, and after polarization is performed for 1 hour at a temperature of 100° C. under an electric field of 6 kV, the film is heated at room temperature. Cool the PVF2 piezoelectric body 14 to
Create.

As shown in FIG. 2, the silver layer on one side of the PVF2 piezoelectric body 14 is patterned to be parallel to its uniaxial stretching direction to form a strip-shaped electrode 15.

These strip-shaped electrodes 15 have a unit element electrode width of 0.9 mm, an electrode length of 35 #, and a unit element gap of 0.1 m, forming 64 elements. Next, the silver layer on the side opposite to the strip-shaped electrode 15 is patterned as necessary to form a common electrode 1.
6, a V-shaped groove 17 having a depth of about 30 μm and a width of about 0.2 rtrm is formed using a cutter or the like at a location corresponding to the folded portion of the common electrode 16. Then, the PV
The F2 piezoelectric body 14 is folded once along the groove portion 17. After this, the V-shaped groove 17 located on the outside of the folded portion
Conductive paste (product name: D-750 manufactured by Fujikura Kasei Co., Ltd.)
18 is applied, dried, and the groove 1 is formed as shown in FIG. 1.
The common electrodes 16 separated by 7 are interconnected to fabricate a laminated piezoelectric body 12.

A lead wire 19a is connected to the copper plate 12, and a lead wire 19b is connected to each strip-shaped electrode 15 of the two front laminated piezoelectric bodies. Further, a polyester film 20 having a thickness of 12 μm is applied to the entire body including the laminated piezoelectric body 13.
is coated, and an epoxy resin layer 21 manufactured by Evotech Co., Ltd. under the trade name 301-2 is injected into the film 20,
The length of the laminated piezoelectric body is fixed to the support body 11 with the piezoelectric body 14 folded over.

According to the present invention, the V-shaped groove 17 is formed on one side of the PVF2 piezoelectric body 14 to be folded, for example, on the common electrode 16 side.
, the piezoelectric body 14 can be easily folded, and the opposing strip-shaped electrodes 15 can be vertically aligned accurately by folding. As a result, it is possible to prevent differences in the electrical impedance of the driving elements due to misalignment of the strip electrodes 15 and short circuits between the driving elements, resulting in a highly reliable linear array type ultrasonic probe. can have a child. In fact, in the linear array type ultrasonic probe of this embodiment, there is no difference in electrical impedance between the unit elements, and moreover, there is no pulse between the 8 elements of the unit element part of the probe and the common electrode 16. When a voltage was applied, it was confirmed that the device operated at a low frequency of 5 MHz.

Further, even when the PVF2 piezoelectric body 14 is folded many times to obtain a linear array type ultrasonic probe with low electrical impedance, the folding operation can be performed extremely easily.

Furthermore, a V-shaped groove 17 is provided in the piezoelectric body 14, and the groove 1
By folding the piezoelectric body 14 along the lines 7, it is possible to prevent the folded portion from bulging out excessively. As a result, when the ultrasonic probe is operated, the effects of acoustic coupling and electrical strokes in the non-voltage applied portion of the strip electrode 15 adjacent to the eight elements of the strip electrode 15 are reduced. It can be done very little. Therefore, a probe with excellent performance can be obtained.

Further, by providing a groove 17 on one surface of the piezoelectric body 14, for example, on the side of the common electrode 16, the common electrode 16 is electrically isolated. By coating the paste 18, electrical isolation of the common electrode can be eliminated.

In addition, in the above embodiment, the PV separated by the V-shaped groove
Although the separated common electrodes were connected by applying a conductive paste to the groove portion of the common electrode on one side of the F2 piezoelectric body, the present invention is not limited to connection using the paste. For example, as shown in FIG. 3(a), a connection metal film 22 may be provided in the groove portion 17 after folding by vapor deposition or sputtering. On the other hand, as shown in FIG. 5(b), due to the structure of the ultrasonic probe, the strip-shaped electrode 15 is disposed outside along the groove 17 provided on the common electrode 16 side of the piezoelectric body 14. When folded, conductive paste 18 may be inserted into the groove 17 inside the folded portion of the piezoelectric body 14 to connect the separated common electrodes. Further, in such a case, a conductive substrate 23 such as a metal thin film may be interposed between the opposing common electrodes 16 as shown in FIG. 3(C).

In the above example, a PVF2 piezoelectric material was used as the polymer piezoelectric material, but fluorine-containing synthetic polymers such as PVF2 and TrFE, other organic polymers exhibiting piezoelectricity, or lead titanate, titanium, etc. A so-called composite piezoelectric material in which a ceramic piezoelectric material powder such as lead zirconate is mixed into a polymer resin can also be used.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to easily fold a polymer piezoelectric material, and when folding the polymer piezoelectric material, it is possible to easily and accurately match the electrode shape patterns formed on both sides of the polymer piezoelectric material. , which in turn improves manufacturability,
It is possible to provide a laminated polymer piezoelectric ultrasonic probe that achieves improved resolution by suppressing the effects of electrical impedance variations, acoustic and electrical coupling, and crosstalk.

[Brief Description of the Drawings] Fig. 1 is a sectional view of a linear array type ultrasonic probe showing an embodiment of the present invention, and Fig. 2 illustrates the production of a laminated piezoelectric material of the ultrasonic probe. Perspective view of Figure 3(a)-(
C) is a sectional view of a main part of an ultrasound probe showing another embodiment of the present invention, and FIGS. 4 and 5 are sectional views of main parts of a conventional ultrasound probe, respectively. 11...Support, Y...Laminated piezoelectric material, 14...P
VF2 piezoelectric body, 15... Strip-shaped electrode, 16... Common electrode, 17... V-shaped groove, 18... Conductive paste, 20... Film, 22... Metal film, 23・・・
・Conductive substrate. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 1L Figure 3

Claims (1)

[Claims] In a laminated polymer piezoelectric ultrasonic probe formed by folding and laminating at least two layers of a polymer piezoelectric material having electrodes formed on both sides, a groove is provided on one surface along the fold line of the polymer piezoelectric material. A laminated polymer piezoelectric ultrasonic probe characterized by being provided with.