JP2022131315A - Ultrasonic transducer, ultrasonic probe, and ultrasonic diagnostic apparatus - Google Patents

Abstract

To provide an ultrasonic transducer having high mechanical strength and excellent directivity.SOLUTION: An ultrasonic transducer comprises: a piezoelectric member including a piezoelectric material; and matching layers arranged on the piezoelectric member. The piezoelectric member includes at least one first groove for dividing the piezoelectric material into a plurality of areas. The first groove of the piezoelectric member is filled with a filling material containing an epoxy resin and an organic filler, and a value at a cumulative percentage of 10% in cumulative particle distribution of the organic filler is equal to or more than 0.9 μm.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ultrasonic transducer, an ultrasonic probe, and an ultrasonic diagnostic apparatus.

Ultrasound diagnostic equipment diagnoses by applying ultrasound probes to or inserting an ultrasound probe into an object to be inspected, including humans and other animals, to irradiate ultrasound waves, and receiving and analyzing the reflected waves. It is a device that performs According to the ultrasonic diagnostic apparatus, it is possible to obtain, for example, the shape and movement of tissue of a living body as an image or video. An ultrasonic diagnostic apparatus has the advantage of being able to perform examinations repeatedly because of its high safety.

An ultrasonic probe used in the ultrasonic diagnostic apparatus incorporates an ultrasonic transducer or the like for transmitting and receiving ultrasonic waves. The ultrasonic transducer receives an electrical signal (transmission signal) from the diagnostic apparatus, converts the received transmission signal into an ultrasonic signal, and transmits the ultrasonic signal. Also, it receives the ultrasonic waves reflected in the object to be inspected, converts them into electric signals (received signals), and transmits them to the diagnostic apparatus.

An ultrasonic transducer consists of a piezoelectric material for converting a signal into an ultrasonic wave or converting a received ultrasonic wave into an electrical signal, and a matching device for matching the acoustic impedance between the piezoelectric material and the object under test. layers, acoustic lenses, etc. to focus the ultrasound waves to the desired location. In order to improve the directivity of such an ultrasonic transducer, conventionally, the piezoelectric material in the piezoelectric material is divided into a plurality of regions, and the spaces between the regions are filled with a filling material. The filler can reduce damage to the piezoelectric material due to external impact and crosstalk between adjacent piezoelectric materials.

For example, Patent Literature 1 proposes filling an epoxy resin having a predetermined bulk elastic modulus between piezoelectric materials. In addition, Patent Document 2 proposes filling silicone resin between piezoelectric materials.

JP 2016-25611 A JP-A-63-164700

As a result of studies by the inventors of the present invention, as in Patent Document 1, placing a relatively hard resin such as epoxy resin between piezoelectric materials enhances the mechanical strength of the ultrasonic transducer and makes it resistant to external impact. sexuality increases. However, there is a problem that the directivity of the ultrasonic transducer tends to decrease. On the other hand, when a relatively soft resin such as silicone resin is placed between piezoelectric materials as in Patent Document 2, the directivity of the ultrasonic transducer is good, but the mechanical strength of the ultrasonic transducer is sufficiently increased. There was a problem that it could not be done.

The present invention has been made in view of such problems. An object of the present invention is to provide an ultrasonic transducer having high mechanical strength and excellent directivity, an ultrasonic probe including the same, and an ultrasonic diagnostic apparatus.

The present invention provides the following ultrasonic transducer.
1. An ultrasonic transducer comprising: a piezoelectric material comprising a piezoelectric material; and a matching layer disposed on said piezoelectric material, said piezoelectric material dividing said piezoelectric material into at least one region. 1 groove, the first groove of the piezoelectric material is filled with a filler containing an epoxy resin and an organic filler, and the cumulative 10% value of the cumulative particle size distribution of the organic filler is 0 .9 μm or greater, an ultrasonic transducer.

The present invention also provides an ultrasonic probe including the ultrasonic transducer described above. Furthermore, the present invention also provides an ultrasonic diagnostic apparatus including the above ultrasonic probe.

According to the present invention, it is possible to provide an ultrasonic transducer having high mechanical strength and good directivity, an ultrasonic probe including the same, and an ultrasonic diagnostic apparatus.

FIG. 1 is a cross-sectional view showing an example of the overall structure of an ultrasonic transducer according to one embodiment of the present invention. 2 is a plan view for explaining the structure of the piezoelectric material of the ultrasonic transducer shown in FIG. 1. FIG. FIG. 3 is a diagram showing a configuration of an ultrasonic diagnostic apparatus including ultrasonic transducers according to one embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic transducer for use in an ultrasonic diagnostic apparatus having an ultrasonic probe, which will be described later. The ultrasonic transducer of the present invention may have at least a piezoelectric material and a matching layer, but usually has a backing material, an electrical terminal extracting layer, an acoustic lens, and the like. FIG. 1 is a cross-sectional view showing an example of the overall structure of an ultrasonic transducer 100 according to one embodiment of the invention. As shown in FIG. 1 of the present embodiment, the ultrasonic transducer 100 includes a backing material 110, an electrical terminal take-out portion (flexible printed circuit board) 120 arranged on the backing material 110, and an electric terminal take-out portion 120. , a matching layer 140 disposed on the piezoelectric material 130 , and an acoustic lens 150 disposed on the matching layer 140 . The piezoelectric material 130 also includes a piezoelectric material 130a and at least one first groove 130b that divides the piezoelectric material 130a into a plurality of regions. Material 160 is filled. Further, in the present embodiment, the matching layer 140 is composed of three layers, part of which (the first matching layer 140a and the second matching layer 140b) is the second layer connected to the first groove 130b. The second groove 140d is also filled with the filler 160. As shown in FIG. Signal electrodes 170a and 170b are arranged on the electrical terminal lead-out portion 120 side and the matching layer 140 side of the piezoelectric material 130, respectively.

As described above, in conventional ultrasonic transducers, it has been proposed to fill the space between piezoelectric materials divided into a plurality of regions with epoxy resin, silicone resin, or the like. However, when the epoxy resin is filled, the hardness of the filler is high and ultrasonic waves are easily transmitted, so the directivity of the obtained ultrasonic transducer tends to be low. On the other hand, when filled with silicone resin, the strength of the filler is not sufficient, and it easily deforms when receiving a mechanical impact such as being dropped, so there is a problem that the piezoelectric material cannot be sufficiently protected. rice field.

Therefore, in the present embodiment, a filling material 160 containing an epoxy resin and an organic filler is placed in the first groove 130b of the piezoelectric material 130 and the second groove 140d of the matching layer 140. FIG. Also, at this time, the cumulative percentage 10% value in the cumulative particle size distribution of the organic filler is adjusted to be 0.9 μm or more.

When the filler 160 contains the epoxy resin in this way, the hardness of the filler 160 is sufficiently hard, and the piezoelectric material 130 is less susceptible to external impact. On the other hand, if the filler 160 has an organic filler having the above cumulative particle size distribution, the organic filler attenuates or scatters ultrasonic waves. Therefore, ultrasonic waves are less likely to be transmitted between adjacent piezoelectric materials 130a, and directivity as well as mechanical strength is improved.

Each configuration of the ultrasonic transducer 100 of this embodiment will be described below. In this specification, the acoustic lens 150 side of the ultrasonic transducer is also referred to as the upper surface side, and the backing material 110 side is also referred to as the rear surface side.

(backing material)
The backing material 110 is a member for supporting an electrical terminal extracting portion 120, which will be described later, the piezoelectric member 130, and the like, and also functions as a member for attenuating ultrasonic waves traveling from the piezoelectric member 130 toward the back side.

Although the backing material 110 is composed of a single layer in the present embodiment, the backing material 110 may be composed of a plurality of layers. In addition, the backing material 110 of this embodiment has a plurality of grooves (not shown) on the interface side with the electrical terminal extraction portion 120 . The planar view shape of the groove is the same as the planar view shape of a first groove 130b formed in the piezoelectric material 130, which will be described later, and the groove communicates with the first groove 130b. Further, the grooves of the backing material 110 are filled with a filling material 160 which will be described later. However, the backing material 110 may not have grooves. On the other hand, the groove may extend from the electrical terminal extraction portion 120 side to the back side of the backing material 110 .

The material of the backing material 110 is not particularly limited, and examples thereof include synthetic rubber filled with a material for adjusting acoustic impedance, natural rubber, epoxy resin, silicone resin, organic material such as thermoplastic resin, Macor glass, and the like. inorganic materials, organic-inorganic composite materials, and the like. Also, the backing material 110 may be made of a porous material or the like having fine voids inside.

Here, the shape of the backing material 110 is not particularly limited as long as it can attenuate transmitted ultrasonic waves.

(Electrical terminal extraction part)
The electric terminal extracting portion 120 is a member for transmitting signals to the piezoelectric material 130a in the piezoelectric material 130 via the signal electrodes 170a and 170b and for receiving signals from the piezoelectric material 130 via the signal electrodes 170a and 170b. is. The electric terminal extracting portion 120 is arranged between the backing material 110 and a piezoelectric material 130 which will be described later. It is also electrically connected to an external power supply, diagnostic equipment, and the like.

In this embodiment, the electrical terminal extracting portion 120 includes a flexible printed circuit board (hereinafter also referred to as “FPC”), and the FPC is divided by a plurality of grooves (not shown). The FPC has wiring that serves as electrodes for the piezoelectric material 130 . The FPC may be commercially available as long as it has the appropriate pattern. The plan view shape of each groove is the same as the plan view shape of the first groove 130b of the piezoelectric material 130 described later, and the groove communicates with the first groove 130b. In addition, the grooves are filled with a filler 160, which will be described later.

(piezoelectric material)
The piezoelectric material 130 includes a piezoelectric material 130a arranged on the electric terminal extraction portion 120 (on the electric terminal extraction portion 120 via the signal electrode 170a in this embodiment), and the piezoelectric material 130a divided into a plurality of regions. and a first groove 130b.

A plan view shape of the piezoelectric material 130 is shown in FIG. 2 shows the shape of the piezoelectric material 130 when the signal electrode 170b, matching layer 140, and acoustic lens 150 are removed from the ultrasonic transducer 100. FIG. The piezoelectric material 130 is provided with first grooves 130b so as to divide the piezoelectric material 130a. The first groove 130b dividing the piezoelectric material 130a means that the first groove 130b divides the region of the piezoelectric material 130a on the matching layer 140 side into a plurality of regions. may be connected on the electrical terminal extracting portion 120 side.

In this embodiment, all of the plurality of piezoelectric materials 130a divided by the first grooves 130b have the same shape. However, the shape of each piezoelectric material 130a is appropriately selected according to the application of the ultrasonic transducer 100, and all of them may not have the same shape. Further, in the present embodiment, the shape of the piezoelectric material 130a divided by the first grooves 130b is a rectangular parallelepiped shape, but the shape of the piezoelectric material 130a divided by the first grooves 130b is not limited to a rectangular parallelepiped shape. The shape is not particularly limited as long as it can oscillate ultrasonic waves in a desired direction.

The thickness of the piezoelectric material 130 is appropriately selected according to the type of ultrasonic transducer and the frequency at which the ultrasonic transducer oscillates.

The width of each first groove 130b of the piezoelectric material 130 is 15-45 μm. As for the depth, if the piezoelectric material 130a is not completely divided by the first grooves 130b, the depth 130b of the first grooves is preferably about 80 to 90% of the thickness of the piezoelectric material 130. FIG. On the other hand, when the piezoelectric material 130a constituting the piezoelectric material 130 is completely divided by the first grooves 130b and no grooves are provided in the matching layer 140, the first grooves 130b are formed in the electrical terminal lead-out portion 120. It is preferable that the combined depth of the groove (not shown) formed in the backing material 110 and the groove formed in the backing material 110 is 10 to 100 μm longer than the thickness of the piezoelectric material 130a. On the other hand, when the piezoelectric material 130a constituting the piezoelectric material 130 is completely divided by the first grooves 130b and the matching layer 140 is also provided with grooves, the first grooves 130b, the second grooves 140d described later, The combined depth of the grooves (not shown) formed in the electrical terminal extraction part 120 and the grooves formed in the backing material 110 is 10 to 100 μm greater than the thickness of the piezoelectric material 130a and the thickness of the matching layer to be cut. It is preferable to make it longer. Also, the interval between adjacent first grooves 130b is 150 to 600 μm, but can be changed as appropriate.

Examples of the piezoelectric material 130a include piezoelectric ceramics such as lead zirconate titanate (PZT); lead magnesium niobate/lead titanate solid solution (PMN-PT); lead zinc niobate/lead titanate solid solution ( piezoelectric single crystals such as PZN-PT); and composite piezoelectric materials obtained by combining these materials with polymer materials.

A plurality of signal electrodes 170 a and 170 b arranged on both sides of the piezoelectric material 130 are electrodes for applying voltage to the piezoelectric material 130 . The signal electrodes 170a and 170b are not particularly limited as long as they are electrically connected to the electrical terminal extraction portion 120 described above and can sufficiently transmit and receive signals to and from the piezoelectric material 130. For example, gold, silver, copper, etc. It can be a layer consisting of

(matching layer)
The matching layer 140 is a layer arranged on the piezoelectric material 130 (in this embodiment, on the signal electrode 170b of the piezoelectric material 130a), and matches the acoustic characteristics between the piezoelectric material 130 and the acoustic lens 150. It is a layer for The matching layer 140 may be composed of a single layer, but is normally composed of multiple layers with different acoustic impedances. The number of matching layers is not particularly limited, and is generally two or more layers. As shown in FIG. 1, in this embodiment, the matching layer 140 is a laminate including a first matching layer 140a, a second matching layer 140b and a third matching layer 140c.

The acoustic impedance of each layer forming the matching layer 140 can be appropriately adjusted by the components forming each layer. For example, when each matching layer 140a, 140b, 140c is a layer containing resin and filler, the acoustic impedance of each layer can be adjusted by adjusting the type and amount of these fillers. The matching layers 140a, 140b, and 140c may be layers containing the same resin and the same filler, or layers containing different resins and/or different fillers. Furthermore, the thickness of each layer may be the same or different.

The type of resin and the type of filler contained in matching layer 140 are not particularly limited. Examples of resins include epoxy resins and the like. On the other hand, examples of fillers include inorganic fine particles such as ferrite; organic fine particles such as silicone fine powder; and the like. In the present embodiment, the composition of third matching layer 140c is different from the composition of filler 160, which will be described later. However, the composition of the third matching layer 140 c may be the same as the composition of the filler 160 .

Also, in this embodiment, the first matching layer 140a and the second matching layer 140b have second grooves 140d connected above the first grooves 130b of the piezoelectric material 130 described above. The plan view shape of the second groove 140d is the same as the plan view shape of the first groove 130b. On the other hand, the uppermost layer of the matching layer 140 closest to the acoustic lens 150 (third matching layer 140c in the present embodiment) does not have the second groove 140d. However, the present invention is not limited to this embodiment, and the uppermost layer (third matching layer 140c) may have the second grooves 140d. Also, the uppermost layer may have grooves that communicate with only some of the plurality of second grooves 140d. In this case, the groove may be filled with the filler 160 , for example, may be a void, or may be filled with a filler having a composition different from that of the filler 160 .

(acoustic lens)
Acoustic lens 150 is a member for converging ultrasonic waves transmitted from piezoelectric material 130 . As shown in FIG. 1, in this embodiment, the acoustic lens 150 is a cylindrical acoustic lens extending in the Y direction of FIG. 1 and protruding in the Z direction. All cross-sectional shapes perpendicular to the X direction are the same. Further, the acoustic lens 150 converges the ultrasonic waves oscillated by the piezoelectric materials 130 a in the Z direction and emits them to the outside of the ultrasonic transducer 100 .

The acoustic lens 150 is made of a material having acoustic properties suitable for an object to be inspected, for example, a living body. For example, the acoustic lens 150 is preferably made of a material, such as silicone rubber, that has an acoustic impedance relatively close to that of the object under test.

(filler)
The filling material 160 is a member that fills the first groove 130b of the piezoelectric material 130, the second groove 140d of the matching layer 140, the grooves of the backing material 110 and the electrical terminal extraction part 120, and the like. A member for suppressing the interference of ultrasonic waves between the piezoelectric materials 130a to increase the directivity of the ultrasonic transducer 100, and for increasing the strength of the ultrasonic transducer 100 and increasing the mechanical resistance to external impact. be.

The filling material 160 is filled without gaps in the first groove 130b of the piezoelectric material 130, the second groove 140d of the matching layer 140, the groove of the backing material 110, and the groove of the electrical terminal lead-out portion 120. preferable. However, there may be some gaps as needed. Further, the first groove 130b of the piezoelectric material 130, the second groove 140d of the matching layer 140, the groove of the backing material 110, and part of the groove of the electrical terminal lead-out portion 120 contain the epoxy resin and the organic filler. A filler having a composition different from that of the filler 160 may be filled.

The filler 160 includes an epoxy resin and an organic filler having a cumulative 10% percentage value of 0.9 μm or more in cumulative particle size distribution. The epoxy resin serves as a binder in the filler 160, and the organic filler is dispersed in the binder.

The epoxy resin contained in the filler 160 is not particularly limited, and examples thereof include bisphenol type epoxy resins such as bisphenol A type and bisphenol F type; novolac type epoxy resins such as resol novolac type and phenol-modified novolac type; naphthalene structure. Polycyclic aromatic type epoxy resins such as containing type, anthracene structure containing type, fluorene structure containing type, etc.; hydrogenated alicyclic type epoxy resins; liquid crystalline epoxy resins and the like are included. The filler 160 may contain only one type of epoxy resin, or may contain two or more types.

Among the above epoxy resins, epoxy resins having a plurality of epoxy groups are preferable from the viewpoint of chemical resistance, and the number of epoxy groups in one molecule can be, for example, 3 to 4. Further, those having a high glass transition temperature (Tg) and those having a high crosslink density are also preferable. Therefore, among the above, the novolak type epoxy resin is preferable.

The amount of the epoxy resin in the filler 160 is preferably 40 parts by mass or more and 60 parts by mass or less, more preferably 40 parts by mass or more and 55 parts by mass or less, with respect to the total amount of the filler 160 of 100 parts by mass. Part by mass or more and 50 parts by mass or less is more preferable. When the proportion of the epoxy resin is 40 parts by mass or more, the strength of the ultrasonic transducer increases. On the other hand, when the proportion of the epoxy resin is 60 parts by mass or less, the amount of the organic filler is relatively increased, and the directivity of the ultrasonic transducer 100 is improved.

On the other hand, the organic filler is not particularly limited as long as it is a particle containing an organic resin and having a predetermined particle diameter, but the organic filler is preferably an elastomer particle. Examples of elastomers that the elastomer particles contain include silicones, urethanes, acrylics, butadiene, and the like.

Here, the 10% cumulative percentage value in the cumulative particle size distribution of the organic filler is 0.9 μm or more. When the 10% cumulative percentage value of the organic filler is 0.9 μm or more, as described above, excellent directivity can be obtained while maintaining the durability (mechanical strength) of the ultrasonic transducer.

The cumulative particle size distribution is calculated based on the measurement results obtained by measuring the particle diameters of about 200 particles with a scanning electron microscope (SEM). Examples of the method for separating the organic filler from the filler composition before curing include a method of removing the epoxy resin in the filler composition by dissolving it in an organic solvent such as ethanol and taking out only the organic filler. be done. On the other hand, when measuring the cumulative particle size distribution from the filler 160, a cross section is cut out from the ultrasonic transducer 100 along the Y direction using a dicing saw, a diamond cutter, or the like, and energy dispersive X-ray analysis (EDS) or wavelength dispersion is performed. Elemental analysis of the filler 160 is performed by type X-ray spectroscopy (WDS). As a result, the element derived from the organic filler (Si in the case of silicone) is mapped to identify the organic filler. Then, the particle size of the specified organic filler is measured with a scanning electron microscope (SEM) to calculate the cumulative particle size distribution. The 10% cumulative percentage value refers to the particle diameter at a cumulative frequency of 10% from the smaller particle size side in the cumulative particle size distribution measured by the above method (hereinafter also referred to as “D ₁₀ ”). Furthermore, when the filler 160 contains a plurality of organic fillers, the cumulative particle size distribution is measured in a state in which all of these are mixed.

Moreover, in the present embodiment, it is preferable that the particle size distribution of the organic filler is wide. When the particle size distribution of the organic filler is wide, a large number of large particles and small particles are present, so small particles are easily filled between large particles. As a result, the path of ultrasonic waves transmitted from one piezoelectric material 130a to the adjacent piezoelectric material 130a is likely to be cut off. As a result, it becomes difficult for the ultrasonic waves to be transmitted between the adjacent piezoelectric materials 130a, and the directivity of the ultrasonic transducer 100 tends to be high.

A cumulative percentage value of 50% and a cumulative percentage value of 90% in the cumulative particle size distribution are indicators of the wide particle size distribution of the organic filler. It can be said that the larger the difference between the 50% cumulative percentage value or 90% cumulative percentage value and the 10% cumulative percentage value, the wider the particle size distribution. The 90% cumulative percentage value is preferably 1.5 μm or more and 3.5 μm or less, more preferably 1.75 μm or more and 3.0 μm or less, and more preferably 2.0 μm or more and 2.5 μm or less. When the 90% cumulative percentage value falls within this range, it becomes easier to obtain excellent directivity while maintaining the durability (strength) of the ultrasonic transducer.

Here, the filler 160 may contain only one kind of organic filler, but preferably contains two or more kinds of organic fillers. When the filler 160 contains two or more kinds of organic fillers, it becomes easier to satisfy the cumulative percentage value of 10%, the cumulative percentage value of 50%, and the cumulative percentage value of 90%.

At least one of the plurality of organic fillers is preferably an organic filler having a structure capable of reacting with the epoxy resin (hereinafter also referred to as "reactive organic filler"). Here, the structure capable of reacting with an epoxy resin means an epoxy group, an amino group, or the like. When the filling material 160 contains a reactive organic filler, the organic filler in the filling material 160 has good dispersibility, and the directivity of the ultrasonic transducer is improved. Whether or not the filler 160 contains a reactive organic filler, that is, whether or not the organic filler has a structure capable of reacting with the epoxy resin is determined by observing the cross section of the filler 160 with a scanning electron microscope (SEM) or the like. can be confirmed by For example, when the filler 160 contains a reactive organic filler, the epoxy resin and the reactive organic filler are in close contact with each other and no gap is observed. On the other hand, when the filler 160 does not have a structure capable of reacting with the epoxy resin, a gap is observed between the epoxy resin and the filler.

The filler 160 may contain only one type of reactive organic filler, or may contain two or more types.

The particle size of the reactive organic filler is preferably 0.1 μm or more and 5.5 μm or less, more preferably 0.1 μm or more and 5.0 μm or less, and even more preferably 0.1 μm or more and 4.5 μm or less. Average particle size is measured by scanning electron microscopy. On the other hand, when the average particle size of the reactive organic filler is 1.2 μm or more, the cumulative particle size distribution described above is easily satisfied.

The reactive organic filler is preferably 10 parts by mass or more and 30 parts by mass or less, more preferably 10 parts by mass or more and 25 parts by mass or less, and further 10 parts by mass or more and 20 parts by mass or less. preferable. When the proportion of the reactive organic filler is 10 parts by mass or more, the dispersibility of the organic filler in the filler 160 is improved. On the other hand, when the proportion of the reactive organic filler is 30 parts by mass or less, the viscosity of the filler composition when producing the filler 160 does not excessively increase, and the first groove 130b and the second The groove 140d and the like can be filled without gaps.

As described above, since the reactive organic filler has a high affinity with the binder resin, it may become difficult to fill the first grooves 130b and the like with the filler 160 when used in large amounts. Therefore, the organic filler, together with the reactive organic filler, has no reactivity with the epoxy resin and has a particle size different from that of the reactive organic filler (hereinafter also referred to as "non-reactive organic filler"). is preferably included.

Examples of non-reactive organic fillers include silicone particles, urethane particles, acrylic particles, butadiene, and the like. Among these, silicone particles are particularly preferable from the viewpoint that the elastic modulus of rubber can be maintained even at low temperatures. The filler 160 may contain only one type of non-reactive organic filler, or may contain two or more types.

The particle diameter of the non-reactive organic filler is preferably 0.3 μm or more and 10.0 μm or less, more preferably 0.5 μm or more and 7.5 μm or less, and preferably 0.7 μm or more and 5.0 μm or less. Average particle size is measured by scanning electron microscopy. When the average particle size of the non-reactive organic filler is 2.0 μm or more, it becomes easier to satisfy the above-described cumulative particle size distribution.

The non-reactive organic filler is preferably 70 parts by mass or more and 90 parts by mass or less, more preferably 75 parts by mass or more and 90 parts by mass or less, and 80 parts by mass or more and 90 parts by mass or less with respect to the total amount of 100 parts by mass of the organic filler. More preferred. When the ratio of the non-reactive organic filler is 90 parts by mass or more, the viscosity of the filler composition when producing the filler 160 does not excessively increase, and the first groove 130b and the second groove described above do not increase. It becomes easy to form the filler 160 on 140d and the like without gaps. On the other hand, when the ratio of the non-reactive organic filler is 70 parts by mass or less, the amount of the reactive organic filler is sufficiently large, and the organic filler is easily dispersed uniformly in the filler 160 .

In addition, the content ratio (total amount) of the organic filler is preferably 40 parts by mass or more and 60 parts by mass or less, more preferably 45 parts by mass or more and 60 parts by mass or less, and 50 parts by mass or more and 60 parts by mass with respect to 100 parts by mass of the filler. Part or less is more preferable. When the proportion of the organic filler is 60 parts by mass or more, the directivity of the ultrasonic transducer 100 is enhanced. On the other hand, when the proportion of the organic filler is 40 parts by mass or less, the proportion of the epoxy resin is sufficiently increased, and the strength of the ultrasonic transducer 100 is increased.

Filler 160 may contain other components, if necessary, in addition to the epoxy resin and organic filler as long as the objects and effects of the present invention are not impaired. Examples of other ingredients include coupling agents. When filler 160 contains a coupling agent, the dispersibility of the non-reactive organic filler described above is enhanced. Examples of coupling agents include silane coupling agents containing epoxy groups and amino groups, titanium coupling agents, and the like.

Coupling agents may be commercially available, examples of which include A-186, A-187, A-1871, A-1100, A-1110, A-1120, A-2120, Y-9669 (any are also trade names, manufactured by Momentive); -402, KBE-403 (both trade names, manufactured by Shin-Etsu Chemical Co., Ltd.); DOWSIL Z-6610 Silane, DOWSIL Z-6011 Silane, XIAMETER OFS-6020 Silane, DOWSIL Z-6094 Silane, DOWSIL Z-6883 Silane, XIAMETER OFS-6032 Silane, DOWSIL Z-6269 Silane, DOWSIL SZ 6032 Silane, XIAMETER OFS-6040 Silane, DOWSIL Z-6044 Silane, DOWSIL Z-6043 Silane ); S310, S320, S330, S340, S350, S510, S530 (all trade names, manufactured by JNC); and Plenact amino group-containing 44 (manufactured by Ajinomoto Fine-Techno Co., Ltd.).

The filler 160 may contain a small amount of inorganic particles, but the amount of the inorganic particles is preferably 10 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the total amount of the filler 160 . When the amount of the inorganic particles in the filler 160 is 1 part by mass or less, the amount of the epoxy resin and the organic filler becomes relatively sufficient, and the above-mentioned degree and directivity can be easily obtained.

(Method for manufacturing ultrasonic transducer)
The method for manufacturing the above-described ultrasonic transducer is not particularly limited as long as the above-described structure can be obtained. An example is shown below, but the method is not limited to this method.

In this manufacturing method, a backing material having no groove, a flat plate-shaped electrical terminal lead-out portion having no groove, signal electrodes formed on both sides, and a flat plate having no first grooves. Bonding piezoelectric materials together (bonding process). Then, a matching layer is formed on the piezoelectric material (signal electrode) (matching layer forming step), and a plurality of grooves are formed from the matching layer side toward the backing material (groove forming step). Thereafter, the grooves formed in the groove forming step are filled with a filler composition, cured (filler forming step), and an acoustic lens is attached onto the matching layer (acoustic lens attaching step). If necessary, steps other than these may be included.

・Bonding process In the bonding process, a plate-shaped backing material without grooves, an electric terminal extraction part without grooves, and a desired circuit etc. are arranged on one sheet of film, and both sides and a plate-shaped piezoelectric material having a signal electrode formed on the substrate and having no first groove. The bonding order is not particularly limited, and the backing material and the electrical terminal extraction portion may be bonded first, or the piezoelectric material and the electrical terminal extraction portion may be bonded together. There is no particular limitation on the method of adhering these together, and for example, they may be adhered with an adhesive or the like.

Also, the method of forming the signal electrodes on the surface of the piezoelectric material is not particularly limited. Alternatively, silver may be baked onto the piezoelectric material. Furthermore, a conductor such as copper may be attached to the piezoelectric material and patterned.

Matching Layer Forming Step In the matching layer forming step, a matching layer is formed on the piezoelectric material (here, one signal electrode). The method of forming the matching layer is not particularly limited, and prefabricated matching layers may be laminated one by one, or a plurality of matching layers may be laminated in advance and laminated to the piezoelectric material. Furthermore, the process of applying the matching layer composition onto the piezoelectric material and curing the composition may be repeated. The matching layer formed in the matching layer forming step does not have the second groove.

Although all the matching layers may be formed in the matching layer forming step, only the matching layer in which the grooves are to be formed is formed when the second grooves are formed only in part of the matching layers.

- Groove forming step In the groove forming step, grooves are formed from the matching layer side to the backing material. A method for forming the groove is not particularly limited, and is appropriately selected according to the width of the first groove and the second groove, the thickness of the piezoelectric material, and the like. For example, it may be cut with a dicing saw or a diamond cutter, or may be cut by Micro Electro Mechanical Systems (MEMS) processing.

Filler Forming Step In the filler filling step, a filler composition is introduced into the grooves formed in the groove forming step and cured. At this time, the grooves are not only filled with the filler composition, but also the filler composition is applied on the matching layer and cured to form a part of the matching layer (for example, the above-mentioned third layer). It may be a matching layer 140c). In this case, the matching layer (for example, the third matching layer 140c described above) formed in the filling material forming step does not have the second groove 140d.

The method of filling the grooves with the filler composition is not particularly limited, and the filler composition may be injected using a spatula or the like, for example. Also, the method of forming the filler composition on the matching layer is not particularly limited.

The filler composition is a composition containing the epoxy resin precursor (hereinafter also referred to as "prepolymer"), the above-described organic filler, and, if necessary, a curing agent, a coupling agent, and the like. .

Examples of prepolymers include the above-mentioned epoxy resin monomers and oligomers. Moreover, the organic filler and the coupling agent are the same as those described above.

On the other hand, examples of curing agents for curing the prepolymer include ethylenediamine, triethylenediamine, hexamethylenediamine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine. triazine compounds such as; 1,8-diazabicyclo[5,4,0]undecene-7 (DBU); triethylenediamine; benzyldimethylamine; triethanolamine; linear aliphatic polyamines; aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone; and modified amines such as amine adducts and ketimine.

Examples of such linear aliphatic polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine and diethylaminopropylamine.

Examples of such cycloaliphatic polyamines include N-aminoethylpiverazine, Ramiron C-260, Araldit HY-964, mencenediamine, isophorone diamine, SCure 211, SCure 212, Wandamine HM, and 1.3BAC (all from ThreeBond company) are included.

Examples of the above aliphatic aromatic polyamines include m.xylylenediamine, Shoramine X, Amine Black, Shoramine Black, Shoramine N, Shoramine 1001 and Shoramine 1010 (all manufactured by ThreeBond).

The method for curing the filler composition is appropriately selected according to the type of the curing agent in the filler composition, but it is usually preferable to solidify the filler composition by heating. A heating temperature is appropriately selected. Heating can be performed by a known method, such as a heater or a constant temperature bath.

Acoustic lens attaching step After the filling material forming step, an acoustic lens is attached on the matching layer. The method of attaching the acoustic lens is not particularly limited, and for example, it can be attached with an adhesive or the like.

2. Ultrasonic Probe and Ultrasonic Diagnostic Apparatus The above-described ultrasonic transducer can be used in an ultrasonic probe 100a, an ultrasonic diagnostic apparatus 10, etc., as shown in FIG. 3, for example. The ultrasonic diagnostic apparatus 10 includes an ultrasonic probe 100a having the above-described ultrasonic transducer, a body section 11, a connector section 12, a display 13, and the like.

The ultrasonic probe 100a only needs to include the ultrasonic transducer (not shown), and is connected to the main body 11 via the cable 14 connected to the connector 12. As shown in FIG.

An electrical signal (transmission signal) from the main body 11 is transmitted through the cable 14 to the piezoelectric material of the ultrasonic probe 100a. This transmitted signal is converted into ultrasonic waves by the piezoelectric material and transmitted into the object to be inspected. The transmitted ultrasound waves are reflected within the object to be examined. A part of the reflected wave is received by the piezoelectric material, converted into an electric signal (received signal), and transmitted to the main body 11 . The received signal is converted into image data in the main unit 11 of the ultrasonic diagnostic apparatus 10 and displayed on the display 13 .

The ultrasonic diagnostic apparatus provided with the ultrasonic transducers of the above-described embodiments has high directivity and can perform accurate diagnosis. Furthermore, since the above-described ultrasonic transducer has high strength and can withstand impact caused by dropping, it can be used for ultrasonic diagnostic apparatuses in various fields.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these.

1. Fabrication of ultrasonic transducer Comparative example 1
A backing material and a flexible printed circuit board (electric terminal extraction part) were adhered in this order onto the fixing plate with an adhesive. A piezoelectric material made of lead zirconate titanate (PZT) and having a size of 4.6 mm×42.5 mm with signal electrodes arranged on both sides was also prepared. Then, the piezoelectric material and the flexible printed circuit board were adhered so that one signal electrode was adjacent to the flexible printed circuit board.

Next, using a dicing saw, the piezoelectric material and the flexible printed circuit board were provided with grooves perpendicular to the laminated surface of each member. The piezoelectric material was formed by forming a plurality of grooves so that the grooves were parallel when viewed from above and positioned at equal intervals. The width of the groove was set to 20 μm. Also, at this time, the depth of the groove was adjusted so that the backing material was not cut completely.

A filler composition was then prepared as follows. Epoxy resin 1 (trade name: C1163A, manufactured by Tesque), organic filler-containing epoxy resin 2 (trade name: EP2240, manufactured by Evonik (including a structure that can react with the epoxy resin on the surface of the organic filler), particle size of the filler : 0.1 to 3 μm), amine curing agent 1 (trade name: C1163B, manufactured by Tesque), and amine curing agent 2 (trade name: ST12, manufactured by Mitsubishi Chemical Corporation) at a mass ratio of 33:37. :17:13.

Then, the filling material composition was applied onto the piezoelectric material with a spatula, and vacuum defoaming was performed for 3 minutes. Three matching layers (a first matching layer, a second matching layer, and a third matching layer) were formed on the signal electrode of the piezoelectric material. Each matching layer was a cured product of a kneaded mixture of epoxy resin and ferrite or silicone fine powder. After heating at 60° C. for 4 hours, an acoustic lens was adhered onto the third matching layer with an adhesive to obtain an ultrasonic transducer 1 .

The above filler composition was put into ethanol to remove the epoxy resin in the filler composition, and only the organic filler was taken out. Then, the particle size of about 200 particles of the organic filler was measured with a scanning electron microscope (SEM), and the cumulative percentage 10% value in the cumulative particle size distribution of the organic filler was calculated based on the measurement results. As a result, it was 0.4 μm.

・Comparative example 2
A backing material and a flexible printed circuit board (electric terminal extraction part) were adhered in this order onto the fixing plate with an adhesive. A piezoelectric material made of lead zirconate titanate (PZT) and having a size of 4.6 mm×42.5 mm with signal electrodes arranged on both sides was also prepared. Then, the piezoelectric material and the flexible printed circuit board were adhered so that one signal electrode was adjacent to the flexible printed circuit board. Similar to Comparative Example 1, two matching layers (a first matching layer and a second matching layer) were formed on the signal electrode of the piezoelectric material.

Next, using a dicing saw, grooves were formed in the matching layers (the first matching layer and the second matching layer), the piezoelectric material layer, and the flexible printed circuit board perpendicular to the lamination plane of each member. In addition, a plurality of grooves were formed so as to be parallel when viewed from above and positioned at equal intervals. The width of the groove was set to 20 μm. Also, at this time, the depth of the groove was adjusted so that the backing material was not cut completely.

A filler composition was then prepared as follows. A silicone resin (trade name: KE-1604, manufactured by Shin-Etsu Chemical Co., Ltd.) and amine curing agent 3 (trade name: CAT1604, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed at a mass ratio of 90:10.

Then, the grooves were filled with the filler composition by applying with a spatula and vacuum defoaming for 3 minutes. Further, a third matching layer was adhered and heated at 60° C. for 2 hours, and then an acoustic lens was adhered onto the matching layer (third matching layer) with an adhesive to obtain an ultrasonic transducer 2 .

・Comparative example 3
The filler composition is composed of epoxy resin 1 (trade name: C1163A, manufactured by Tesque) and organic filler-containing epoxy resin 2 (trade name: EP2240, manufactured by Evonik (the organic filler has a structure capable of reacting with the epoxy resin on the surface). )), amine curing agent 1 (trade name: C1163B, manufactured by Tesque), and amine curing agent 2 (trade name: ST12, manufactured by Mitsubishi Chemical Corporation) at a mass ratio of 33:37:17:13. An ultrasonic transducer 3 was obtained in the same manner as in Comparative Example 2, except that the composition was mixed with and heated at 60° C. for 4 hours.

In the same manner as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and taken out, and the cumulative percentage value of 10% in the cumulative particle size distribution of the organic filler was compared with a scanning electron microscope (SEM). When specified in the same manner as in Example 1, it was 0.4 μm.
・Comparative example 4
A composition obtained by adding 30 parts by mass of tungsten trioxide powder to 100 parts by mass of the filler composition of Comparative Example 3 was used as a filler composition, and was heated at 60 ° C. for 4 hours. An ultrasonic transducer 4 was produced in the same manner.

In the same manner as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and taken out, and the cumulative percentage value of 10% in the cumulative particle size distribution of the organic filler was compared with a scanning electron microscope (SEM). When measured by the same method as in Example 1, it was 0.4 μm.

・Comparative example 5
To 100 parts by mass of the filler composition of Comparative Example 3, 50 parts by mass of silicone composite powder (trade name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd., particle size: 0.7 to 5 μm) was added. An ultrasonic transducer 5 was produced in the same manner as in Comparative Example 2, except that the filler composition was used and heated at 60° C. for 4 hours.

In the same manner as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and taken out, and the cumulative percentage value of 10% in the cumulative particle size distribution of the organic filler was compared with a scanning electron microscope (SEM). When measured by the same method as in Example 1, it was 0.8 μm.

・Example 1
To 100 parts by mass of the filler composition of Comparative Example 3, 75 parts by mass of silicone composite powder (trade name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd., particle size: 0.7 to 5 μm) was added. An ultrasonic transducer 6 was produced in the same manner as in Comparative Example 2, except that the filler composition was used and heated at 60° C. for 4 hours.

By the same method as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and taken out, and the cumulative percentage value of 10% in the cumulative particle size distribution of the organic filler was compared with a scanning electron microscope (SEM). When measured by the same method as in Example 1, it was 0.9 μm.

・Example 2
To 100 parts by mass of the filler composition of Comparative Example 3, 100 parts by mass of silicone composite powder (trade name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd., particle size: 0.7 to 5 μm) was added. An ultrasonic transducer 7 was produced in the same manner as in Comparative Example 2, except that the filler composition was used and heated at 60° C. for 4 hours.

By the same method as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and taken out, and the cumulative percentage value of 10% in the cumulative particle size distribution of the organic filler was compared with a scanning electron microscope (SEM). When measured by the same method as in Example 1, it was 1.0 μm.

2. Evaluation The directivity and intensity of each of the above ultrasonic transducers were evaluated by the following methods. Table 1 shows the results.

(1) Directivity Evaluation Method An ultrasonic probe including the above-described ultrasonic transducer was placed near the water surface of a water tank in which a spherical target was placed. A pulser receiver and an oscilloscope were electrically connected to the ultrasonic probe. The pulser receiver was Olympus ultrasonic pulser receiver: MODEL5900PR, and the oscilloscope was TFF oscilloscope: TDS5032.

Then, the directivity of the ultrasonic probe was obtained by transmitting ultrasonic waves from the probe head portion of the ultrasonic probe immersed in water toward a spherical target and receiving the reflected waves. The angles between the spherical target and the elements in the ultrasonic probe to be measured are -40°, -30°, -20°, -10°, 0°, +10°, +20°, +30°, +40°. The presence or absence of ripples was evaluated in the directivity at each angle, specifically in the transmission/reception frequency characteristics at each angle. The angle was set to 0° when the spherical target and the element in the ultrasonic probe to be measured were positioned on a straight line. Evaluation was based on the following criteria.
(Evaluation criteria)
○: The maximum sensitivity S _MAX and the minimum ripple part in the transmission and reception frequency characteristics when the angle between the spherical target and the measurement target element of the ultrasonic probe to be measured is ±40°. The absolute value of the difference ΔS of the sensitivity S _MIN is less than 10 dB △: Maximum transmission and reception frequency characteristics when the angle between the spherical target and the measurement target element of the ultrasonic probe to be measured is ±40 ° The absolute value ΔS of the difference between the sensitivity S _MAX and the minimum sensitivity S _MIN of the rippled portion is 10 dB or more and less than 20 dB ×: between the spherical target and the measurement target element of the ultrasonic probe to be measured In the transmission and reception frequency characteristics when the angle is ±40°, the absolute value ΔS of the difference between the maximum sensitivity S _MAX and the minimum sensitivity S _MIN of the ripple portion is 20 dB or more

(2) Drop test evaluation method An ultrasonic probe having the ultrasonic transducer described above was prepared. Then, a weight having a steel ball at the tip and having the same weight as the ultrasonic probe (excluding cables and connectors) was dropped onto the top surface of the acoustic lens of the ultrasonic probe. The height from which the weight was dropped was started at a position 10 cm higher than the acoustic lens and increased in 10 cm increments. Each time, the capacitance of the ultrasonic probe was evaluated, and the test was continued until a decrease in capacitance was observed, up to a maximum of 122 cm.
(Evaluation criteria)
◯: The difference between the capacitance Sa of the ultrasonic transducer after dropping the weight from a height of 122 cm and the capacitance Sb before the test is -5 pF or less. If not ×: The capacitance Sa of the ultrasonic transducer after dropping the weight from a height of 122 cm is compared with the capacitance Sb before the test, and the difference Sa-Sb = ΔSc is -5 pF or less. When there are 1ch or more elements

3. result

As shown in Table 1 above, the piezoelectric material has grooves (first grooves) separating the piezoelectric materials, and the grooves contain an epoxy resin and an organic filler. When the 10% value (D ₁₀ ) was 0.9 μm or more, the directivity of ultrasonic waves was good and the drop test results were good (Examples 1 and 2).

On the other hand, even if the filler contained an organic filler, when the cumulative percentage of 10% (D ₁₀ ) in the cumulative particle size distribution was less than 0.9 μm, the directivity was likely to be low (Comparative Example 1, 3-5). In addition, when the filler was a silicone resin containing no organic filler, although the directivity was good, the result of the drop test was low (Comparative Example 2).

The ultrasonic transducer of the present invention has high mechanical strength and excellent directivity. Therefore, it is useful for various ultrasonic diagnostic apparatuses and the like.

REFERENCE SIGNS LIST 10 ultrasonic diagnostic apparatus 11 main body 12 connector 13 display 14 cable 100 ultrasonic transducer 100a ultrasonic probe 110 backing material 120 electrode terminal extraction part 130 piezoelectric material 130a piezoelectric material 130b first groove 140 matching layer 140a first matching Layer 140b Second matching layer 140c Third matching layer (top layer)
140d Second groove 150 Acoustic lens 160 Filler 170a, 170b Signal electrode

Claims (11)

a piezoelectric material comprising a piezoelectric material;
at least one matching layer disposed on the piezoelectric material;
An ultrasonic transducer comprising
the piezoelectric material further comprising at least one first groove dividing the piezoelectric material into a plurality of regions;
the first groove of the piezoelectric material is filled with a filler containing an epoxy resin and an organic filler;
The cumulative percentage 10% value in the cumulative particle size distribution of the organic filler is 0.9 μm or more.
ultrasonic transducer. the matching layer having a second groove connected to the first groove of the piezoelectric material;
The second groove is filled with the filler,
The ultrasonic transducer according to claim 1. wherein the matching layer is a laminate of multiple layers, a top layer of the multiple layers not having the second groove;
The ultrasonic transducer according to claim 2. the top layer has the same composition as the filler;
The ultrasonic transducer according to claim 3. The organic filler is elastomer particles.
The ultrasonic transducer according to any one of claims 1-4. The organic filler contains at least one resin selected from the group consisting of silicone, urethane, acrylic, and butadiene,
The ultrasonic transducer according to any one of claims 1-5. The organic filler contains two or more types of elastomer particles,
The ultrasonic transducer according to any one of claims 1-6. The organic filler has a structure on its surface that can react with the epoxy resin,
The ultrasonic transducer according to any one of claims 1-6. wherein the filler comprises a coupling agent;
The ultrasonic transducer according to any one of claims 1-8. comprising the ultrasonic transducer according to any one of claims 1 to 9,
ultrasound probe. Including the ultrasonic probe according to claim 10,
Ultrasound diagnostic equipment.

Images