KR101753492B1 - The ultrasonic transducer having backing layer comprising materials having different acoustic impedances and method for manufacturing thereof - Google Patents

The ultrasonic transducer having backing layer comprising materials having different acoustic impedances and method for manufacturing thereof Download PDF

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KR101753492B1
KR101753492B1 KR1020150170791A KR20150170791A KR101753492B1 KR 101753492 B1 KR101753492 B1 KR 101753492B1 KR 1020150170791 A KR1020150170791 A KR 1020150170791A KR 20150170791 A KR20150170791 A KR 20150170791A KR 101753492 B1 KR101753492 B1 KR 101753492B1
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ultrasonic transducer
acoustic impedance
layer
piezoelectric element
width
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KR20170064830A (en
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정종섭
지선미
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동국대학교 산학협력단
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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    • A61B8/4483—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer
    • A61B8/4494—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer characterised by the arrangement of the transducer elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
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Abstract

The present invention relates to an ultrasonic transducer having a backside layer composed of a plurality of materials having different acoustic impedances and a method of manufacturing the same. More particularly, the backside layer includes a first material, a second material, and a third material having different acoustic impedances Wherein the first material is bonded to a portion of the bottom surface of the piezoelectric element, the second material is bonded to the rest of the bottom surface of the piezoelectric element and disposed in side-by-side contact with the first material, And the first material, the second material, and the third material may be joined together to form a back layer. According to the rear layer structure of the ultrasonic transducer according to the present invention, since the reflected echo signals at the boundaries of the plurality of materials having different acoustic impedances are canceled by the phase difference, the acoustic energy incident through the rear layer can be attenuated, It is possible to manufacture an ultrasonic transducer for weight reduction or miniaturization.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an ultrasonic transducer having a back layer composed of materials having different acoustic impedances, and an ultrasonic transducer having a back layer composed of materials having different acoustic impedances,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transducer for industrial or medical use, and a manufacturing method for manufacturing an ultrasonic transducer that is lighter or smaller, and an ultrasonic transducer manufactured by the manufacturing method. More particularly, And a method of manufacturing the same.

The general structure of the ultrasonic transducer is a stack structure composed of a piezoelectric layer, a matching layer, and a backing layer. A piezoelectric element is a key component of an ultrasonic transducer that generates a piezoelectric effect and a reverse piezoelectric effect. When an electric signal is applied to the piezoelectric element, mechanical vibration occurs in the piezoelectric element, and acoustic energy is transmitted to the medium. When the reflected energy in the medium returns to the element, it is converted into an electrical signal to image the internal structure of the medium.

The matching layer of the ultrasonic transducer is attached to the front surface of the piezoelectric element to reduce the difference in acoustic impedance between the piezoelectric element and the medium, and is manufactured to have a thickness of 1/4 of the wavelength, .

The piezoelectric element can transmit or receive acoustic energy in both directions of the piezoelectric element. In order for the ultrasonic transducer to have high performance, it is necessary to transmit and receive a large amount of energy in the direction of the medium, . In order to obtain such an effect, a back layer is attached to the back surface of the piezoelectric element, that is, the opposite side of the medium. Therefore, the back layer attenuates the acoustic energy generated in the rear direction of the piezoelectric element and shortens the reverberation, thereby enhancing the resolution of the ultrasound image.

The ideal backing layer material is a material similar to the acoustic impedance of a piezoelectric element and having a high attenuation characteristic. As the acoustic impedance of the back layer has a value similar to the acoustic impedance of the piezoelectric element, the energy reflected at the boundary between the piezoelectric element and the back layer material is small, so that the pulse length of the signal can be shortened, However, there is a problem that the sensitivity of the signal is reduced. Thus, the back layer material of a typical medical ultrasound transducer has an acoustic impedance of about 3 to 8 Mrayl.

Generally, the back layer is made thick to maximize the attenuation of the incoming acoustic energy. However, miniaturized transducers such as transducers, IVUS transducers, and cMUTs, which are used in systems where portability is important, such as wireless ultrasonic probes, can not make the thickness of the backing layer sufficiently thick, so that the thickness is made thin. In this case, Can not be sufficiently attenuated and is reflected by the back layer and the air layer and returns to the piezoelectric element and is coupled to the transmission / reception signal, thereby causing a problem that the waveform is distorted.

In addition, in the case of applying the rear layer material having a high acoustic impedance, since the energy of the transducer is lowered and the energy transferred to the inside of the rear layer is relatively larger than the energy transferred to the medium, The problem of insufficient damping due to the reduction of the thickness of the back layer becomes more remarkable.

The rear layer structure of the ultrasonic transducer according to an embodiment of the present invention effectively suppresses the acoustic energy transferred to the inside of the back layer and minimizes the echo signals that may occur in the back layer due to the thickness reduction of the ultrasonic transducer. The rear surface layer structure of the ultrasound transducer according to an embodiment of the present invention can cancel the phase of the echo signal generated in the back layer by using the relative acoustic impedance relationship of the material to mitigate the distortion of the transmission / reception signal due to the echo signal And the thickness of the back layer can be minimized.

The ultrasonic transducer backside layer structure according to an embodiment of the present invention is characterized in that an ultrasonic echo signal progressing from a high acoustic impedance material to a low acoustic impedance material and an ultrasonic echo signal progressing from a low acoustic impedance material to a high acoustic impedance material A phase difference of 180 degrees (°) can be generated. That is, it is the rear layer structure of the ultrasonic transducer proposed in an embodiment of the present invention to have an interface at which two echo signals whose phases are opposite to each other can occur due to the relative acoustic impedance vertical relationship of materials. More specifically, the rear layer structure of the ultrasonic transducer according to an embodiment of the present invention is such that two kinds of materials having high acoustic impedance and low acoustic impedance are separated from each other at half the area of the bottom surface of the piezoelectric element and bonded to the bottom surface of the piezoelectric element, Is a structure in which a substance having an intermediate acoustic impedance is attached to two kinds of materials. The material attached to the back of the back layer of the ultrasonic transducer according to an embodiment of the present invention should be a material having relatively high sound absorption characteristics.

According to the rear surface layer of the ultrasonic transducer according to an embodiment of the present invention, an echo signal generated at the inner boundary surface of the rear layer can be suppressed by the phase cancellation action, and the energy transmitted behind the boundary surface, It can be absorbed by the material attached to the most backside. Therefore, since the acoustic energy entering the back layer can be minimized without increasing the thickness of the back layer of the ultrasonic transducer, the distortion of the transmission and reception signals due to the echo signal can be mitigated and the thickness of the back layer can be minimized.

In addition, according to the structure of the rear surface layer of the ultrasonic transducer according to the embodiment of the present invention, by attaching a substance having a high acoustic impedance and a substance having a low acoustic impedance to the bottom surface of a piezoelectric element, bandwidth and sensitivity can be improved, . As a result, by applying the translucent backside layer structure according to an embodiment of the present invention to the ultrasonic transducer, it is possible to lighten the ultrasonic transducer and contribute to improvement of the performance of the ultrasonic transducer.

As an embodiment of the present invention, an ultrasonic transducer may be provided in which a back layer is formed on the bottom surface of the piezoelectric element and includes a plurality of materials having different acoustic impedances. According to the ultrasonic transducer according to the embodiment of the present invention, the echo signals reflected at the boundaries of the plurality of materials having different acoustic impedances are canceled by the phase difference, so that the acoustic energy incident through the rear layer can be attenuated.

The rear surface layer of the ultrasonic transducer according to an embodiment of the present invention may include a first material, a second material, and a third material having different acoustic impedances. The first material is bonded to a portion of the bottom surface of the piezoelectric element, The material is bonded to the rest of the bottom surface of the piezoelectric element and disposed in side-by-side contact with the first material, the third material is continuously bonded to the bottom surface of the first material and the second material and the first material, 3 material can form a back layer by bonding.

In one embodiment of the present invention, the acoustic impedance of the first material is greater than the acoustic impedance of the second material and the third material, the acoustic impedance of the second material is less than the acoustic impedance of the first material and the third material, 3 The acoustic impedance of the material may have an intermediate value of the acoustic impedance of the first and second materials.

In one embodiment of the present invention, the first material may have a value such that the acoustic impedance is greater than or equal to about 10 Mrayl and less than or equal to 20 Mrayl, and the second material may have a value such that the acoustic impedance is less than or equal to about 2 Mrayl and less than or equal to 10 Mrayl.

In the rear surface layer of the ultrasonic transducer according to an embodiment of the present invention, any one of the first material, the second material, and the third material may have a thickness adjusted so that the generation times of the echo signals are the same at the respective joint surfaces.

The thickness of any one of the first material, the second material and the third material of the back layer according to an embodiment of the present invention can be determined by the following equation.

Figure 112015118048349-pat00001
(d: thickness, t: constant, c: sound velocity of each material)

According to an embodiment of the present invention, the acoustic impedance difference between the first material and the third material and the acoustic impedance difference between the second material and the third material may be about 2 Mrayl or more and 10 Mrayl or less.

The back layer structure of the ultrasound transducer according to one embodiment of the present invention can be applied to any one of a single-element type ultrasonic transducer, an ultrasonic transducer of an array type, and an ultrasonic transducer in the form of a composite .

As an embodiment of the present invention, a method of manufacturing a back layer of an ultrasonic transducer can be provided. A method according to an embodiment of the present invention includes the steps of attaching a first material and a third material to form a back layer of an ultrasonic transducer in bulk form to a bottom surface of a first material, Dicing the first material from the top surface to the bottom surface direction to form a tooth width, filling the formed tooth width with the second material, and curing. Also, some of the first and third materials may be diced using a blade having a predetermined width.

The width of the blade according to an embodiment of the present invention can be set so that the sum of the width of the first remaining material and the width of the width of the tooth after dicing is equal to the device pitch P of the ultrasonic transducer of the multi-element type. The width of the blade according to an embodiment of the present invention may also be set to be equal to half of the width of the ultrasonic transducer of the single element type.

The back layer of the ultrasonic transducer fabricated by the method according to an embodiment of the present invention may be attached to the back surface of the piezoelectric element for the multi-element converter or attached to the rear surface of the piezoelectric element for the converter in the form of a single element or a composite , And optionally cutting corresponding to the size of the production target ultrasound transducer.

Since the structure of the rear surface layer of the ultrasonic transducer according to an embodiment of the present invention can effectively suppress the acoustic energy transmitted to the back surface layer, the performance of the ultrasonic transducer can be improved even when a thin layer of back surface is applied have. Therefore, the ultrasound transducer according to an embodiment of the present invention contributes to weight reduction of a converter for a general B-mode image, or may be applied to a small converter such as an IVUS converter, a cMUT, etc., to improve the performance of an ultrasonic converter.

Fig. 1 shows a conventional cross-sectional structure of a medical ultrasound transducer, in which (a) shows a single-element type transducer structure and (b) shows a multi-element type transducer structure.
FIG. 2 shows a simulation result of an FEM (finite element method) for an echo signal generated when the thickness of the back layer of the conventional ultrasonic transducer is reduced.
3 illustrates a back layer structure of an ultrasonic transducer according to an embodiment of the present invention.
FIG. 4 illustrates a mechanism by which the acoustic energy transmitted to the back layer is attenuated by the back layer structure according to an embodiment of the present invention.
FIG. 5 shows a result of a finite element method (FEM) simulation that confirms that a phase difference of a signal occurs according to a relative acoustic impedance of a material.
FIG. 6 illustrates the time axis and frequency axis waveforms that may occur when a back layer according to an embodiment of the present invention is applied.
FIG. 7 shows a simulation result of a finite element method (FEM) comparing the case where the conventional back layer is applied to the ultrasonic transducer with a thin thickness and the case where the back layer according to the embodiment of the present invention is applied with the same thickness.
FIG. 8 illustrates a structure in which a back layer according to an embodiment of the present invention can be applied to various types of ultrasonic transducers, wherein (a) is applied to a multi-element type ultrasonic transducer, (b) Type ultrasonic wave conversion is designed as a composite type.
FIG. 9 is a view illustrating a method of manufacturing a rear layer structure of an ultrasonic transducer according to an embodiment of the present invention. Referring to FIG. 9, when the sum of the widths of the remaining first material and the width of the tooth width after dicing the blade width is larger than that of the multi- And the device pitch is set equal to the device pitch (Pitch).
FIG. 10 illustrates a method of fabricating a back layer structure of an ultrasonic transducer according to an embodiment of the present invention, in which the blade width is set to be equal to half the width of a single-element type ultrasonic transducer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

The terms used in this specification will be briefly described and the present invention will be described in detail.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Also, in certain cases, there may be a term selected arbitrarily by the applicant, in which case the meaning thereof will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term, not on the name of a simple term, but on the entire contents of the present invention.

When an element is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements, without departing from the spirit or scope of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a conventional cross-sectional structure of a medical ultrasound transducer, in which (a) shows a single-element transducer structure and (b) shows a multi-element type transducer structure. The ultrasonic transducer is generally composed of a matching layer 1, a piezoelectric element 2 and a backside layer 3 and has a sequentially stacked structure such as a single element type transducer shown in Fig. 1 (a) have. The transducer of the multi-element type shown in FIG. 1 (b) is formed by dicing a single piezoelectric element 2 to have a constant width to form a Kerf 4, and then forming an acoustic impedance, such as an epoxy, And then separated into a plurality of multiple elements by a non-conductive material having a low damping characteristic and a low damping characteristic. Then, a matching layer 1 is formed on the piezoelectric element 2, a flexible printed circuit board (FPCB) Are sequentially stacked so that the devices can be operated independently.

FIG. 2 shows a simulation result of an FEM (finite element method) for an echo signal generated when the thickness of the back layer of the conventional ultrasonic transducer is reduced. In the simulation, a single-element ultrasound transducer with a center frequency of 5.5 MHz with a conventional bulk structure backside layer 3 was used. The center frequency used in the simulation is arbitrarily determined, and the applicable frequency range is not limited in the present invention. The simulation results of Figs. 2 (a) and 2 (b) show the results of the simulation with epoxy epoxy / 20% tungsten mixture (E-solder3022, acoustic impedance: 5.9 Mrayl, damping coefficient: 110 dB / Epotek301 / 20% tungsten powder composite, acoustic impedance: 8.6 Mrayl, damping coefficient: 31 dB / mm @ 30 MHz) as back layer (3) material. The back layer (3) material is one of the materials commonly used to construct the back layer (3) of the ultrasonic transducer.

In FIG. 2, a solid line indicates a received signal when the rear layer is applied to a thickness of about 10 mm (37?), And a dotted line indicates a reverberation signal (Ripple) generated when the rear layer thickness is reduced to 1 ?. The result is that the acoustic energy delivered into the backside layer 3 due to the reduced thickness of the backside layer 3 is not sufficiently attenuated and the signal is reflected and distorted by being mixed with the received signal. Further, as the acoustic impedance is applied to the rear layer 3 material, the acoustic energy generated in the element is transmitted to the rear layer 3 in a relatively greater amount than in the medium. Therefore, sensitivity of the received signal is lowered, (3) the problem of insufficient damping increases.

3 illustrates a back layer structure of an ultrasonic transducer according to an embodiment of the present invention. The rear surface layer of the ultrasonic transducer according to an embodiment of the present invention includes a plurality of materials formed on the bottom surface of the piezoelectric element 2 having different acoustic impedances and the acoustic energy incident through the rear surface layer has a plurality of acoustic impedances The echo signals reflected at the boundaries of the materials of the first and second electrodes can be attenuated by being canceled by the phase difference.

Referring to FIG. 3, a plurality of materials having different acoustic impedances constituting the rear layer include a first material 6, a second material 7, and a third material 8, Can be joined to a part of the bottom surface of the piezoelectric element 2. The second material 7 is bonded to the rest of the bottom surface of the piezoelectric element 2 and can be disposed in side by side contact with the first material 6 and the third material 8 can be in contact with the first material 6, 2 material 7, as shown in Fig. Thus, the first material 6, the second material 7, and the third material 8 may form a backside layer by bonding.

The acoustic impedance of the first material 6 according to an embodiment of the present invention is greater than the acoustic impedance of the second material 7 and the third material 8 and the acoustic impedance of the second material 7 is greater than the acoustic impedance of the first material 6. [ Is less than the acoustic impedance of the first material 6 and the third material 8 and the acoustic impedance of the third material 8 may have a median value of the acoustic impedance of the first material 6 and the second material 7. [ . Meanwhile, the third material 8 may be made of a material having excellent sound absorption properties.

The back layer structure according to an embodiment of the present invention shown in FIG. 3 includes a structure for utilizing a fixed / free-end reflection principle in which the phase of a wave reflected at a boundary between materials is changed according to a relative up- to be. The phases of the echo signals reflected at the boundary between the second material 7 and the third material 8 and the echo signals reflected at the boundary between the first material 6 and the third material 8 are 180 ° out of phase with each other And the two reflected signals can be canceled each other.

In other words, the specific mechanism in which the acoustic energy is attenuated by the back layer structure according to the embodiment of the present invention is as shown in FIG.

The acoustic energy transmitted and received through the piezoelectric element 2 is transmitted to the rear layer 9 and the echo signals reflected from the inner boundary surface due to the difference in thickness of the rear layer material and the acoustic impedance difference are 180 ° out of phase with each other (10). The remaining energy transmitted in the backward direction without being reflected at each interface is absorbed by the third material 8, which is the rear material (11). As a result, most of the acoustic energy transferred into the back layer is suppressed and the echo signal returning to the piezoelectric element 2 can be minimized.

FIG. 5 shows a result of a finite element method (FEM) simulation that confirms that a phase difference of a signal occurs according to a relative acoustic impedance of a material.

5 (a) shows a result of observing an echo signal reflected at two material boundaries when a low acoustic impedance material is attached to the rear surface of the piezoelectric element 2 and a high acoustic impedance material is attached to the rear surface of the piezoelectric element 2, 5 (b) shows a case in which a high acoustic impedance material is attached to the rear surface of the piezoelectric element 2 and a low acoustic impedance material is attached to the rear surface of the piezoelectric element 2, contrary to FIG. 5 (a) . The dotted lines in the graphs (a) and (b) show the echo signals reflected at the inner boundary of the back layer containing two materials of different acoustic impedances. The two echo signals shown in (a) and (b) Can be confirmed that the phases are opposite to each other.

Meanwhile, the first material 6 according to an embodiment of the present invention has an acoustic impedance of approximately 10 Mrayl or more and 20 Mrayl or less, and the second material 7 has a value of approximately 2 Mrayl or more and 10 Mrayl or less Lt; / RTI > This is not a fixed range of values and, in some cases, materials with acoustical impedance values outside the range of presentation may be used.

The difference in acoustic impedance between the first material 6 and the third material 8 and between the second material 7 and the third material 8 is less than about 2 Mrayl and less than 10 Mrayl, The more similar the acoustic impedance difference at each joint surface is, the more effectively the cancellation of the echo signal can be made possible. The values may also use materials with acoustical impedance values that are outside the presentation range, as the case may be. When the amplitudes of the two generated echo signals show a large difference in acoustic impedance difference between the two bonding surfaces or due to the nature of the materials, by adjusting the ratio of the first material 6 and the third material 8, ≪ / RTI >

Any one of the first material 6, the second material 7, and the third material 8 according to an embodiment of the present invention may have a thickness adjusted so that the generation times of the echo signals in the respective bonding surfaces are the same . Because the sound speed is different for each material, it is necessary to control the thickness of the material in order for the echo signals at each boundary to occur at the same time. The thickness d of the material contained in the back layer up to each boundary can be expressed as the product of the sound velocity c of each material and the time t of the echo signal generation at the inner boundary of the back layer.

Figure 112015118048349-pat00002

However, the echo signal generation time t is a constant that can be arbitrarily determined. If the sound velocities of the first material 6 and the second material 7 are 1000 m / s and 2000 m / s, respectively, according to an embodiment of the present invention, the echo signals of the two materials occur at the same time of 1 μs The first material 6 should have a thickness of 0.5 mm and the second material 7 should have a thickness of 1 mm in order for the two echo signals to cancel each other out.

FIG. 6 illustrates the time axis and frequency axis waveforms that may occur when a back layer according to an embodiment of the present invention is applied. 6 (a) is a waveform for each of the first material 6 and the third material 8, FIG. 6 (b) is a waveform for the case where only the second material 7 and the third material 8 are applied, 6 (c) shows the resultant waveform when the first material 6, the second material 7, and the third material 8 are applied to the entire back layer structure according to an embodiment of the present invention. 6 (a) and 6 (b) is canceled out and minimized in the waveform of FIG. 6 (c). Further, by applying the back layer structure according to an embodiment of the present invention, the sensitivity of the frequency band is improved and the signal of -6 dB bandwidth (BW) is improved than that of FIG. 6 (b) . As an embodiment of the present invention, the back layer thickness applied to the simulation is about 1 mm (5?), The first material 6 is an epoxy / tungsten mixture having a density of 5105 kg / m 3 and a sonic velocity of 1865 m / s, (7) has a density of 1150 kg / m 3 and a sound velocity of 2650 m / s. The third material (8) has a density of 3200 kg / m 3 , a sound velocity of 1850 m / Lt; / RTI > was applied.

FIG. 7 shows a simulation result of a finite element method (FEM) in which a conventional back layer is applied to an ultrasonic transducer and a back layer according to an embodiment of the present invention is compared. In FIG. 7, the above graph is a simulation result when a conventional bulk layer type back layer is applied, and the following graph shows a simulation result when a back layer structure according to an embodiment of the present invention is applied. For comparison, the back layer thickness and the final acoustic impedance in both cases are the same. Referring to the graph shown in the dotted line, it can be seen that the echo signal generated in the conventional back layer structure is minimized in the back layer structure according to the embodiment of the present invention.

The structure of the rear surface layer of the ultrasonic transducer according to an embodiment of the present invention can be applied to any one of a single element type ultrasonic transducer, an ultrasonic transducer of an array type, and an ultrasonic transducer in the form of a composite . As shown in FIG. 8 (a), the present invention can be applied to a multi-element type ultrasonic transducer in which one rear layer structure according to an embodiment of the present invention is applied to one element. The present invention is also applicable to a case where a single element converter is designed in the form of a composite as shown in FIG. 8 (b). The back layer according to an exemplary embodiment of the present invention can be applied to various types of structural ultrasound transducers.

As shown in FIGS. 9 and 10, a method for manufacturing a rear layer of an ultrasonic transducer according to an embodiment of the present invention includes a first material 6 and a third material 8 for constituting a rear layer of an ultrasonic transducer (12) of attaching a third material (8) in bulk form to the bottom surface of the first material (6), dicing the first material (6) with the third material (8) A step 13 of forming the tooth width 4 and a step 14 of filling and curing the second material 7 on the formed tooth 4.

According to an embodiment of the present invention, the rear surface layer of the ultrasonic transducer fabricated by the method (12, 13, 14) is attached (15) to the rear surface of the piezoelectric element for multi- Or attaching to the back surface of a piezoelectric element for a transducer in the form of a single element or a composite, and cutting 17 corresponding to the size of the production target ultrasound transducer.

According to one embodiment of the present invention, a portion of the first material 6 and the third material 8 may be diced using a blade 19 having a predetermined width. In the case of FIG. 9, the width of the blade 19 according to the embodiment of the present invention is such that the sum of the width of the remaining first material 6 after dicing and the width of the width 4 is larger than that of the multi- Width, and in the case of FIG. 10, it can be set to be equal to half of the width of the ultrasonic transducer of the single-element type. On the other hand, the width of the blade 19 set in Figs. 9 and 10 can be adjusted by repeating the operation of the thin blade 19 several times in succession.

In addition, the rear block structure according to an embodiment of the present invention can be manufactured through various processes such as molding a mold or using various precision machines.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

1: matching layer
2: piezoelectric element
3: Conventional backside layer
4: Kerf
5: FPCB (Flexible Printed Circuit Board)
6: First material of the back layer
7: Second material of the back layer
8: Third material in the back layer
9: Mechanism of rear layer structure I
10: Mechanism of rear layer structure II
11: Mechanism of back layer structure III
12: Fabrication process of back layer I
13: Fabrication process of back layer II
14: Fabrication process of back layer III
15: Fabrication process of rear layer IV (for multi-element transducer)
16: Fabrication process of back layer IV (for single device converter)
17: Fabrication process of back layer V (for single device converter)
18: Back layer for single-element transducer
19: Blade

Claims (12)

In the ultrasonic transducer,
Wherein the rear surface layer of the ultrasonic transducer is formed on the bottom surface of the piezoelectric element and includes a first material, a second material and a third material having different acoustic impedances,
Wherein the first material is bonded to only a part of the bottom surface of the piezoelectric element, the second material is bonded to the rest of the bottom surface of the piezoelectric element, and the first material and the second material are adjacent to each other, And the third material is bonded to both the bottom surface of the first material and the bottom surface of the second material,
The acoustic energy incident through the rear layer is canceled by a phase difference with an echo signal reflected at a boundary between the second material and the third material and an echo signal reflected at a boundary between the first material and the third material Wherein the ultrasonic transducer is attenuated.
delete The method according to claim 1,
Wherein the acoustic impedance of the first material is greater than the acoustic impedance of the second material and the third material and the acoustic impedance of the second material is less than the acoustic impedance of the first material and the third material, Wherein the acoustic impedance of the material has an intermediate value between the acoustic impedance of the first material and the acoustic impedance of the second material.
The method of claim 3,
Wherein the first material has an acoustic impedance of 10 Mrayl or more and 20 Mrayl or less and the second material has a value whose acoustic impedance is 2 Mrayl or more and 10 Mrayl or less, Of the acoustic impedance of the ultrasonic transducer.
The method according to claim 1,
Wherein the first material, the second material, and the third material have a thickness adjusted so that the generation times of the two echo signals are the same.
6. The method of claim 5,
Wherein the thickness is determined by the following equation.
Figure 112015118048349-pat00003

(d: thickness, t: constant, c: sound velocity of each material)
The method of claim 3,
Wherein an acoustic impedance difference between the first material and the third material and a difference between the acoustic impedance of the second material and the acoustic impedance of the third material are respectively not less than 2 Mrayl and not more than 10 Mrayl.
8. The method according to any one of claims 1 to 7,
Wherein the structure of the rear surface layer of the ultrasonic transducer is applicable to any one of a transducer of a single-element type ultrasonic transducer, an ultrasonic transducer of an array type, and an ultrasonic transducer in the form of a composite. .
A method of manufacturing a back layer of an ultrasonic transducer,
Attaching a first material and a third material to constitute a rear layer of the ultrasonic transducer in a bulk form on the bottom surface of the first material;
Dicing the first material to which the third material is attached from the upper surface to the lower surface to form a tooth width; And
Filling the formed tooth with a second material and curing,
Wherein a portion of the first material and the third material is diced using a blade having a predetermined width,
Wherein the first material, the second material, and the third material have different acoustic impedances, and the back layer of the ultrasonic transducer fabricated according to the steps is attached to the bottom surface of the piezoelectric element,
Wherein the first material is bonded to only a part of the bottom surface of the piezoelectric element, the second material is bonded to the rest of the bottom surface of the piezoelectric element, and the first material and the second material are adjacent to each other, And the third material is bonded to both the bottom surface of the first material and the bottom surface of the second material,
The acoustic energy incident through the rear layer is canceled by a phase difference with an echo signal reflected at a boundary between the second material and the third material and an echo signal reflected at a boundary between the first material and the third material Wherein the ultrasonic transducer is attenuated.
10. The method of claim 9,
Wherein the width of the blade is a width set such that the sum of the width of the first remaining material after dicing and the width of the width of the first material is the same as the element spacing of the multi-element type ultrasonic transducer.
10. The method of claim 9,
Wherein the width of the blade is set to be equal to one-half of the width of the single-element type ultrasonic transducer.
12. The method according to any one of claims 9 to 11,
Attaching the back surface layer of the ultrasonic transducer fabricated according to the above method to the rear surface of the piezoelectric element for the multi-element converter or attaching it to the back surface of the single-element or composite-type transducer piezoelectric element; And
Further comprising the step of cutting the ultrasound transducer to correspond to the size of the ultrasound transducer.

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