JP3806349B2 - Ultrasonic probe backing and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a backing for an ultrasonic probe and a method for manufacturing the same, and more particularly to a technique for improving the acoustic characteristics of the backing.
[0002]
[Prior art and problems]
As the ultrasonic transducer, various ultrasonic transducers such as a single transducer, a one-dimensional array transducer, and a two-dimensional array transducer are known. A backing (back side load member) for attenuating and absorbing unnecessary ultrasonic waves radiated backward from the ultrasonic transducer is provided on the back side of such an ultrasonic transducer. The backing may be used as a support member for the ultrasonic transducer. When the acoustic characteristics (physical properties) of the backing are not good, the ultrasonic wave cannot be sufficiently absorbed in the backing, and as a result, the image quality of the ultrasonic image is deteriorated. In particular, it is desirable that the acoustic impedance in the backing is a value as designed and the acoustic impedance is uniform as a whole.
[0003]
Conventionally, a rubber material in which ferrite powder is mixed is used as a backing. However, such a backing has a problem that it is difficult to increase the attenuation rate of ultrasonic waves. In addition, such a backing cannot exhibit sufficient rigidity in relation to processing such as element cutting, and for this reason, it is difficult to apply it to, for example, an array vibrator composed of a large number of minute vibration elements. There is a problem.
[0004]
Conventionally, a backing formed by mixing powder (particles) such as tungsten and glass microballoons (particles) with an epoxy resin is also known. According to this backing, high rigidity and high damping characteristics can be obtained. However, as is well known, particles such as tungsten have a very large weight (density) per unit volume, so when they are mixed into an epoxy resin or the like, the particles settle to the lower part, and in the vertical direction (thickness In the direction), the number of particles per unit volume is non-uniform. That is, there is a problem that the acoustic properties (especially acoustic impedance) of the backing cannot be made uniform in the vertical direction. For the same reason, there is a problem that it is difficult to manufacture a backing having acoustic properties as designed (reproducibility cannot be ensured).
[0005]
An object of the present invention is to improve acoustic properties of a backing.
[0006]
Another object of the present invention is to provide a backing having uniform acoustic properties and a method for manufacturing the same.
[0007]
Another object of the present invention is to improve reproducibility in the manufacture of backings.
[0008]
[Means for Solving the Problems]
(1) In order to achieve the above object, the present invention provides a backing for an ultrasonic probe that is provided behind an ultrasonic transducer and attenuates the ultrasonic wave radiated backward from the ultrasonic transducer. A base material and a plurality of composites mixed in the base material, each of the composites being put into the first material as a base material having a first acoustic impedance, and the first material Different from the first material , a second material having a second acoustic impedance, and a material contained in the first material, the third material being different from the first material. look including a third material having a second acoustic impedance and the third acoustic impedance is characterized by each different from the first acoustic impedance.
[0009]
According to the said structure, a some composite_body | complex is put in a base material, The composite_body | complex is comprised as what put the 2nd material and the 3rd material with respect to the base material (1st material). Therefore, the second material and the third material can always be handled integrally. As a result, for example, the second material and the third material are prevented from being unevenly distributed in the base material due to the difference in weight per unit volume between the second material and the third material. Reproducibility can be improved.
[0010]
Nozomu Mashiku, said second acoustic impedance is higher than the first acoustic impedance, said third acoustic impedance is lower than said first acoustic impedance.
[0011]
Preferably, the weight per unit volume of the second material is different from the weight per unit volume of the third material. Preferably, the weight per unit volume of the second material is larger than the weight per unit volume of the third material. In the composite, effective scattering and absorption of ultrasonic waves can be exhibited with the difference in acoustic impedance of each material.
[0012]
Desirably, the weight per unit volume of the composite corresponds to the weight per unit volume of the base material. According to this configuration, each composite can be more evenly dispersed in the base material.
[0013]
Preferably, the second material is composed of at least one component of tungsten and tantalum. Preferably, the third material has a minute hollow body structure.
[0014]
Preferably, the base material is made of an insulating material, and the first material is made of an insulating material. Preferably, the base material and the first material are made of the same material.
The present invention is a backing for an ultrasonic probe that is provided behind an ultrasonic transducer and attenuates ultrasonic waves radiated backward from the ultrasonic transducer, and is mixed with the matrix and the matrix. A plurality of composites, wherein each composite is a first material as a base material having a first acoustic impedance, and a material placed in the first material, the first material and A second material having a second acoustic impedance and a material placed in the first material, the third material having a third acoustic impedance unlike the first material, The weight per unit volume of the second material is different from the weight per unit volume of the third material. The present invention also provides an ultrasonic probe backing that is provided behind an ultrasonic transducer and attenuates ultrasonic waves radiated backward from the ultrasonic transducer. A plurality of composites mixed with each other, wherein each composite is a first material as a base material having a first acoustic impedance, and a material placed in the first material, and a second acoustic A second material having an impedance; and a third material having a third acoustic impedance, the material being placed in the first material, wherein a weight per unit volume of the composite is a unit of the base material It corresponds to the weight per volume.
[0015]
(2) Moreover, in order to achieve the said objective, this invention is provided in the back of an ultrasonic transducer | vibrator, and is in the backing for ultrasonic probes which attenuates the ultrasonic wave radiated | emitted back from the ultrasonic transducer | vibrator. A base material and a plurality of composites uniformly dispersed and mixed in the base material, wherein each composite is made of a material different from the base material and the base material, and an acoustic impedance And a plurality of types of particles that are different from each other in weight per unit volume.
[0016]
(3) Moreover, in order to achieve the said objective, in this invention, the manufacturing method of the backing for ultrasonic probes WHEREIN: The pre-process which manufactures several composite_body | complex, and said several composite_body | complex with respect to a base material And a post-process for manufacturing the backing by mixing, wherein the pre-process includes an addition process for adding the second material and the third material to the fluid first material, the second material and A curing step of curing the first material to which the third material is added to generate an original composite material; and a pulverizing step of pulverizing the original composite material to generate the plurality of composites. And
[0017]
According to the above configuration, after adding the second material and the third material to the first material, they are pulverized to produce a plurality of composites (usually powders), which are mixed into the base material. A backing is manufactured.
[0018]
Preferably, the method includes a removing step of removing the upper layer after the raw composite material is cured, and the raw composite material from which the upper layer has been removed is pulverized in the pulverizing step.
[0019]
Preferably, the method includes a sorting step of sorting out a plurality of composites generated by the pulverization and having a size within a predetermined range, and the plurality of composites sorted in the sorting step are used in the subsequent step. Is done.
[0020]
Desirably, the weight per unit volume of the second material is greater than the weight per unit volume of the first material, and per unit volume of the third material than the weight per unit volume of the first material. The weight of is smaller.
[0021]
Desirably, the acoustic impedance of the second material is higher than the acoustic impedance of the first material, and the acoustic impedance of the third material is lower than the acoustic impedance of the first material.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 shows a preferred embodiment of an ultrasonic probe according to the present invention, and FIG. 1 is an explanatory view showing the main part thereof. FIG. 1A shows a cross-sectional view of the main part of the ultrasonic probe, and FIG. 1B schematically shows an enlarged view of a portion indicated by reference numeral 100 in FIG. Has been shown. In FIG. 1A, the array transducer 12 is a one-dimensional array transducer or a two-dimensional array transducer. The array transducer 12 includes a plurality of transducer elements 12A. A matching layer 18 is formed on the upper side of the array transducer 12. Specifically, the matching layer 18 includes a first matching layer 14 and a second matching layer 16. The first matching layer 14 is constituted by a plurality of matching elements 14A, and similarly, the second matching layer 16 is also constituted by a plurality of matching elements 16A. An acoustic lens or the like is disposed above the matching layer 18 as necessary.
[0024]
On the other hand, a backing 10 is provided below the array transducer 12, that is, on the back side. The backing 10 functions as a back load material and scatters and absorbs unnecessary ultrasonic waves radiated rearward from the array transducer 12. The structure itself shown in FIG. 1A is known, but in this embodiment, the composition of the backing 10 is different from the conventional one. Incidentally, in FIG. 1A, signal electrodes and ground electrodes provided on the upper surface and the lower surface of the vibration element 12A are not shown. The present invention can also be applied to the case where the lead 20 is provided for each vibration element 12A in the backing 10.
[0025]
FIG. 1B shows an enlarged view of a region indicated by reference numeral 100 in FIG. The composition of the backing 10 will be described with reference to FIG.
[0026]
In the present embodiment, a large number of composites (powder) 24 are added in a substantially uniform manner in the base material 22. The composite 24 includes a base material 26 as a first material, and particles 28 as a second material and particles 30 as a third material added to the base material 26. The acoustic impedance of the particles 28 is larger than the acoustic impedance of the substrate 26, and the density (weight per unit volume) of the particles 28 is larger than the density of the substrate 26. On the other hand, the acoustic impedance of the particles 30 is smaller than the acoustic impedance of the substrate 26, and the density of the particles 30 is smaller than the density of the substrate 26. That is, the ultrasonic wave is scattered and absorbed by the acoustic impedance relationship of the three materials. In the present embodiment, particles having a high density and particles having a low density are added in a composite manner in the composite 24, so that the dispersion uniformity is higher than when the particles 28 and the particles 30 are simply added to the base material 22. Can be improved. In other words, the density of the composite is higher than the density of the base material by combining particles with a higher density and particles with a lower density so that the density of the composite is higher than the density of the base. Close to the density of the material. Therefore, the problem of density gradient that occurs when they exist alone can be reduced. Desirably, the density of the composite 24 as a whole corresponds to or close to the density of the base material 22.
[0027]
FIG. 2 shows an example of each material. As the base material 22 shown in FIG. 1, for example, a thermosetting adhesive such as an epoxy resin can be used. As the first material shown in FIG. 1, for example, an adhesive having rubber elasticity such as silicone rubber or urethane resin or a thermosetting adhesive such as epoxy resin can be used. Here, the base material and the first material can be made of the same material.
[0028]
As the second material constituting the particles 28 shown in FIG. 1, for example, tungsten, tungsten carbide, tungsten silicide, tantalum, or the like can be used. Moreover, as a 3rd material which comprises the particle | grains 30 shown in FIG. 1, micro hollow structures, such as glass microballoons and resin microballoons, can be used.
[0029]
The composite 24 in FIG. 1 is manufactured by a pulverization process as will be described later, and its particle size is preferably 50 to 250 μm, for example, but of course, the particle size can be set to other values. The base material and the first material are materials having electrical insulation, and electrical insulation between the leads can be ensured even when a plurality of leads are inserted into the backing 10.
[0030]
The addition amount of the composite 24 with respect to the base material 22 and the addition amounts of the second material and the third material with respect to the first material can be set to desired amounts. Specifically, the acoustic properties necessary for the backing What is necessary is just to determine each addition amount so that (acoustic impedance, attenuation coefficient), etc. may become a desired value. In addition, since the backing 10 does not use the ferrite powder as described in the conventional example, high rigidity can be ensured. Therefore, it is possible to enhance the rigidity while enhancing the damping characteristics, and to configure a backing having a high practical value.
[0031]
Next, an example of the manufacturing method of the backing according to the present embodiment will be described with reference to FIGS. FIG. 3 shows a manufacturing process of the composite 24 shown in FIG. 1 as a flowchart, and FIG. 4 shows a manufacturing process of the backing by adding the composite to the base material. 3 and 4, epoxy resin is used as the base material 22 shown in FIG. 1, silicone rubber is used as the base material 26, tungsten particles are used as the second material, and third A glass microballoon is used as a material.
[0032]
In step S101 of FIG. 3, first, in order to create a silicone rubber as a fluid, a main agent and a curing agent are mixed in advance and stirred sufficiently. A predetermined amount of tungsten particles is added to the silicone rubber as a fluid. Further, a predetermined amount of glass microballoon is added. After the addition, the silicone rubber is sufficiently stirred. In this case, for example, ultrasonic vibration may be applied together with stirring.
[0033]
In S102, a defoaming process is performed to expel bubbles taken in the composite material created in S101 under a vacuum environment. Incidentally, when the step S101 is performed in a vacuum, the step S102 can be omitted.
[0034]
In S103, the composite material after the defoaming treatment is cured as a thin layer under normal temperature and humidity conditions. In this case, the thickness of the thin layer is 4 mm, for example.
[0035]
In S104, after the hardening process in S103, the supernatant layer in the composite material solidified as a thin layer is removed using, for example, a cutter. As a result, parts that are difficult to use as a complex are removed. In this case, the thickness of the supernatant layer to be removed is 1 mm, for example. In addition, what is necessary is just to determine suitably about said hardening conditions, the removal conditions of a supernatant layer, etc. according to the composition of a composite_body | complex or the material used for it.
[0036]
In S105, the composite material from which the supernatant layer has been removed is applied to a pulverizer, and a pulverization process is performed. Here, the particle size of the powder obtained by the pulverization is preferably, for example, 50 to 250 μm. In order to make the particle diameters more uniform, it is desirable to perform a sieving process using a sieve or the like in S106. Through the above steps, the composite 24 shown in FIG. 1 is manufactured as a powder.
[0037]
Next, in FIG. 4, a main agent as an epoxy resin and a curing agent are mixed in advance and sufficiently stirred. Then, a predetermined amount of the powder produced in the step shown in FIG. 3 is added to the epoxy resin as the fluid and sufficiently stirred. Incidentally, when a lead array is provided in the backing, the lead array can be embedded at the same time in the step S201.
[0038]
In S202, the material created in S201 is placed in a vacuum and the defoaming process is performed in the same manner as described above. Of course, when the process of S201 is performed in a vacuum, the process of S202 can be omitted. In S203, the material after the defoaming treatment is allowed to stand for a predetermined time (for example, 5 hours) at a constant high temperature such as 80 ° C., thereby curing the material. In step S204, the cured material is subjected to outer shape processing and finished in a desired shape. As a result, the backing 10 shown in FIG. 1 is created.
[0039]
As described above, according to the present embodiment, there is an advantage that the acoustic properties such as the acoustic impedance and the attenuation characteristic can be made uniform in the backing 10 and the backing can be easily created with reproducibility. Further, there is an advantage that it can be easily changed so as to be able to cope with a wide range of required acoustic impedances while substantially maintaining the damping coefficient of the backing.
[0040]
【The invention's effect】
As described above, according to the present invention, the acoustic properties of the backing can be improved. Further, there is an advantage that a backing having uniform acoustic properties can be manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a backing according to the present invention.
FIG. 2 is an explanatory view showing an example of each material.
FIG. 3 is a flowchart showing a manufacturing process of a composite.
FIG. 4 is a flowchart showing a manufacturing process of a backing.
[Explanation of symbols]
10 backing, 12 array transducer, 18 matching layer, 22 matrix, 24 composite, 26 substrate (first material), 28 particles (second material), 30 particles (third material).

Claims (17)

An ultrasonic probe backing that is provided behind the ultrasonic transducer and attenuates the ultrasonic wave radiated backward from the ultrasonic transducer,
With the base material,
A plurality of composites mixed in the base material;
Including
Each of the complexes is
A first material as a substrate having a first acoustic impedance;
A material contained in the first material, unlike the first material , a second material having a second acoustic impedance;
A material contained in the first material, unlike the first material , a third material having a third acoustic impedance;
Only including,
The backing for an ultrasonic probe, wherein the second acoustic impedance and the third acoustic impedance are different from the first acoustic impedance . The backing of claim 1 ,
The second acoustic impedance is higher than the first acoustic impedance;
The backing for an ultrasonic probe, wherein the third acoustic impedance is lower than the first acoustic impedance. The backing of claim 1,
The backing for an ultrasonic probe, wherein the weight per unit volume of the second material is different from the weight per unit volume of the third material. The backing of claim 3 ,
The backing for an ultrasonic probe, wherein the weight per unit volume of the second material is larger than the weight per unit volume of the third material. The backing of claim 1,
The backing for an ultrasonic probe, wherein the second material is composed of at least one component of tungsten and tantalum. The backing of claim 1,
The backing for an ultrasonic probe, wherein the third material has a micro hollow body structure. The backing of claim 1,
The backing for an ultrasonic probe, wherein the base material is made of an insulating material. The backing of claim 1,
The backing for an ultrasonic probe, wherein the first material is made of an insulating material. The backing of claim 1,
The backing for an ultrasonic probe, wherein the base material and the first material are made of the same material. An ultrasonic probe backing that is provided behind the ultrasonic transducer and attenuates the ultrasonic wave radiated backward from the ultrasonic transducer,
With the base material,
A plurality of composites mixed in the base material;
Including
Each of the complexes is
A first material as a substrate having a first acoustic impedance;
A material contained in the first material, unlike the first material, a second material having a second acoustic impedance;
A material contained in the first material, different from the first material; A third material having a dance;
Including
The backing for an ultrasonic probe, wherein the weight per unit volume of the second material is different from the weight per unit volume of the third material. An ultrasonic probe backing that is provided behind the ultrasonic transducer and attenuates the ultrasonic wave radiated backward from the ultrasonic transducer,
With the base material,
A plurality of composites mixed in the base material;
Including
Each of the complexes is
A first material as a substrate having a first acoustic impedance;
A material contained in the first material, the second material having a second acoustic impedance;
A material contained in the first material, the third material having a third acoustic impedance;
Including
A backing for an ultrasonic probe, wherein a weight per unit volume of the composite corresponds to a weight per unit volume of the base material. In the backing for an ultrasonic probe that is provided behind the ultrasonic transducer and attenuates the ultrasonic wave emitted backward from the ultrasonic transducer,
With the base material,
A plurality of composites uniformly dispersed and mixed in the base material;
Including
Each of the composites includes a base material and a plurality of types of particles that are made of a material different from the base material and have different acoustic impedance and weight per unit volume. Backing for the probe. In the manufacturing method of the backing for an ultrasonic probe,
A pre-process for producing a plurality of composites;
A post-process for producing the backing by mixing the plurality of composites with a base material;
Including
The pre-process includes
An addition step of adding the second material and the third material to the fluid first material;
A curing step of curing the first material to which the second material and the third material are added to produce an original composite material;
Crushing step of crushing the raw composite material to produce the plurality of composites;
The manufacturing method of the backing for ultrasonic probes characterized by including these. 14. The method of claim 13, wherein
A removal step of removing the upper layer after curing of the raw composite material,
A method of manufacturing a backing for an ultrasonic probe, wherein the raw composite material from which the upper layer has been removed is pulverized in the pulverizing step. 14. The method of claim 13, wherein
Including a sorting step of sorting out a plurality of composites generated by the pulverization having a predetermined range of size,
In the post-process, a plurality of composites selected in the selection process are used. A method for manufacturing an ultrasonic probe backing. 14. The method of claim 13, wherein
The weight per unit volume of the second material is greater than the weight per unit volume of the first material;
A method for manufacturing a backing for an ultrasonic probe, wherein the weight per unit volume of the third material is smaller than the weight per unit volume of the first material. 14. The method of claim 13, wherein
The acoustic impedance of the second material is higher than the acoustic impedance of the first material,
A method for manufacturing a backing for an ultrasonic probe, wherein the acoustic impedance of the third material is lower than the acoustic impedance of the first material.

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