Ultrasonic transducer, ultrasonic probe, and ultrasonic diagnostic device

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

[Technical field]

[0001] The present invention relates to an ultrasonic transducer, an ultrasonic probe, and an ultrasonic diagnostic device. [Background technology]

[0002] An ultrasound diagnostic device is a device that performs diagnosis by applying an ultrasound probe to or inserting it into a subject to be examined, including humans and other animals, irradiating the subject with ultrasound, receiving the reflected waves, and analyzing them. With this ultrasound diagnostic device, it is possible to obtain images or videos of, for example, the shape and movement of tissues of a living body. The ultrasound diagnostic device has the advantage that it is highly safe and can be used for repeated examinations.

[0003] The ultrasonic probe used in the ultrasonic diagnostic device includes an ultrasonic transducer for transmitting and receiving ultrasonic waves. The ultrasonic transducer receives an electric signal (transmission signal) from the diagnostic device, converts the received transmission signal into an ultrasonic signal, and transmits it. It also receives ultrasonic waves reflected from the object under test, converts the reflected signal into an electric signal (reception signal), and transmits it to the diagnostic device.

[0004] An ultrasonic transducer includes a piezoelectric material for converting signals into ultrasonic waves and converting received ultrasonic waves into electrical signals, a matching layer for matching the acoustic impedance between the piezoelectric material and the object to be inspected, and an acoustic lens for focusing ultrasonic waves at a desired position. In order to improve the directivity of such ultrasonic transducers, the piezoelectric material in the piezoelectric material has been conventionally divided into a plurality of regions and a filler material is filled between the regions. The filler material can reduce damage to the piezoelectric material due to external impact and crosstalk between adjacent piezoelectric materials.

[0005] For example, Patent Document 1 proposes filling the gaps between piezoelectric materials with an epoxy resin having a predetermined bulk modulus, and Patent Document 2 proposes filling the gaps between piezoelectric materials with a silicone resin. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-25611 A [Patent Document 2] Japanese Patent Publication No. 63-164700 Summary of the Invention [Problem to be solved by the invention]

[0007] As a result of the study by the present inventors, when a relatively hard resin such as epoxy resin is placed between the piezoelectric materials as in Patent Document 1, the mechanical strength of the ultrasonic transducer is increased and durability against external impact is improved. However, there is a problem that the directivity of the ultrasonic transducer is easily reduced. On the other hand, when a relatively soft resin such as silicone resin is placed between the piezoelectric materials as in Patent Document 2, although the directivity of the ultrasonic transducer is good, there is a problem that the mechanical strength of the ultrasonic transducer cannot be sufficiently increased.

[0008] The present invention has been made in view of the above problems, and has an object to provide an ultrasonic transducer having high mechanical strength and good directionality, and an ultrasonic probe and ultrasonic diagnostic device including the same. [Means for solving the problem]

[0009] The present invention provides the following ultrasonic transducer. An ultrasonic transducer comprising a piezoelectric material including a piezoelectric material and a matching layer disposed on the piezoelectric material, wherein the piezoelectric material further has at least one first groove dividing the piezoelectric material into a plurality of regions, the first groove of the piezoelectric material being filled with a filler including an epoxy resin and an organic filler, and the 10% cumulative percentage value in a cumulative particle size distribution of the organic filler is 0.9 μm or more.

[0010] The present invention also provides an ultrasonic probe including the ultrasonic transducer described above.Furthermore, the present invention also provides an ultrasonic diagnostic device including the ultrasonic probe described above. Effect of the Invention

[0011] According to the present invention, it is possible to provide an ultrasonic transducer having high mechanical strength and good directionality, an ultrasonic probe including the same, and an ultrasonic diagnostic device. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the overall structure of an ultrasonic transducer according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view illustrating the structure of the piezoelectric material of the ultrasonic transducer shown in FIG. [Diagram 3] FIG. 3 is a diagram showing the configuration of an ultrasonic diagnostic apparatus including an ultrasonic transducer according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] 1. Ultrasonic transducer The present invention relates to an ultrasonic transducer for use in an ultrasonic diagnostic device having an ultrasonic probe 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 electric terminal take-out 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 an embodiment of the present invention. As shown in FIG. 1 of this embodiment, the ultrasonic transducer 100 includes at least a backing material 110, an electric terminal take-out portion (flexible printed circuit board) 120 arranged on the backing material 110, a piezoelectric material 130 arranged on the electric terminal take-out portion 120, a matching layer 140 arranged on the piezoelectric material 130, and an acoustic lens 150 arranged on the matching layer 140. The piezoelectric material 130 has a piezoelectric material 130a and at least one first groove 130b that divides the piezoelectric material 130a into a plurality of regions, and the first groove 130b is filled with a filler 160. In this embodiment, the matching layer 140 is made up of three layers, some of which (the first matching layer 140a and the second matching layer 140b) have a second groove 140d connected to the first groove 130b, and the second groove 140d is also filled with the filler 160. Signal electrodes 170a and 170b are disposed on the electrical terminal lead-out portion 120 side and the matching layer 140 side of the piezoelectric material 130, respectively.

[0015] As mentioned above, in the conventional ultrasonic transducer, it has been proposed to fill the spaces between the piezoelectric material divided into a plurality of regions with epoxy resin, silicone resin, or the like. However, when epoxy resin is filled, the hardness of the filler is high and ultrasonic waves are easily transmitted, so that the directionality of the obtained ultrasonic transducer is likely to be low. On the other hand, when silicone resin is filled, the strength of the filler is insufficient, and it easily deforms when subjected to mechanical shock such as dropping, and there is a problem that the piezoelectric material cannot be sufficiently protected.

[0016] Therefore, in this embodiment, the filler 160 containing an epoxy resin and an organic filler is disposed in the first groove 130b of the piezoelectric material 130 and the second groove 140d of the matching layer 140. In addition, the cumulative percentage 10% value in the cumulative particle size distribution of the organic filler is adjusted to be 0.9 μm or more.

[0017] When the filler 160 contains epoxy resin in this way, the hardness of the filler 160 becomes sufficiently hard, and even if it receives an external impact, the piezoelectric material 130 is not easily affected. On the other hand, when the filler 160 contains an organic filler having the above-mentioned cumulative particle size distribution, the ultrasonic waves are attenuated or scattered by the organic filler. Therefore, the ultrasonic waves are not easily transmitted between adjacent piezoelectric materials 130a, and not only the mechanical strength but also the directionality is improved.

[0018] Hereinafter, each component of the ultrasonic transducer 100 of this embodiment will be described. In this specification, the acoustic lens 150 side of the ultrasonic transducer is also referred to as the upper side, and the backing material 110 side is also referred to as the back side.

[0019] (Backing material) The backing material 110 is a member for supporting an electric terminal outlet 120, which will be described later, the piezoelectric material 130, etc., and also functions as a member for attenuating ultrasonic waves traveling from the piezoelectric material 130 to the rear surface side.

[0020] In this embodiment, the backing material 110 is configured as a single layer, but the backing material 110 may be configured as 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 lead-out portion 120. The planar shape of the groove is the same as the planar shape of the first groove 130b formed in the piezoelectric material 130 described below, and the groove communicates with the first groove 130b. In addition, the groove of the backing material 110 is filled with a filler 160 described below. However, the backing material 110 does not have to have a groove. On the other hand, the groove may extend from the electrical terminal lead-out portion 120 side to the back side of the backing material 110.

[0021] The material of the backing material 110 is not particularly limited, and examples thereof include organic materials such as synthetic rubber, natural rubber, epoxy resin, silicone resin, and thermoplastic resin filled with a material for adjusting acoustic impedance, inorganic materials such as Macol glass, organic-inorganic composite materials, etc. Furthermore, the backing material 110 may be made of a porous material having minute voids therein.

[0022] Here, the shape of the backing material 110 is not particularly limited as long as it can attenuate the transmitted ultrasonic waves.

[0023] (Electrical terminal outlet) The electrical terminal lead-out portion 120 is a member for transmitting signals to the piezoelectric material 130a in the piezoelectric material 130 via the signal electrodes 170a, 170b, and for receiving signals from the piezoelectric material 130 via the signal electrodes 170a, 170b. The electrical terminal lead-out portion 120 is disposed between the backing material 110 and the piezoelectric material 130 described below. It is also electrically connected to an external power source, a diagnostic device, and the like.

[0024] In this embodiment, the electrical terminal outlet 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 an electrode for the piezoelectric material 130. The FPC may be a commercially available product as long as it has an appropriate pattern. The planar shape of each groove is the same as the planar shape of a first groove 130b of the piezoelectric material 130 described below, and the grooves communicate with the first groove 130b. The grooves are filled with a filler 160 described below.

[0025] (Piezoelectric material) The piezoelectric material 130 includes a piezoelectric material 130a arranged on the electrical terminal outlet 120 (in this embodiment, on the electrical terminal outlet 120 via the signal electrode 170a) and a first groove 130b dividing the piezoelectric material 130a into multiple regions.

[0026] The planar shape of the piezoelectric material 130 is shown in Fig. 2. Fig. 2 shows the shape of the piezoelectric material 130 when the signal electrode 170b, the matching layer 140, and the acoustic lens 150 are removed from the ultrasonic transducer 100. In the piezoelectric material 130, a first groove 130b is provided 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 area of ​​the piezoelectric material 130a on the matching layer 140 side into a plurality of areas, and for example, the divided piezoelectric materials 130a may be connected to each other on the electrical terminal lead-out portion 120 side.

[0027] In this embodiment, the shapes of the plurality of piezoelectric materials 130a divided by the first grooves 130b are all the same. However, the shape of each piezoelectric material 130a is appropriately selected according to the application of the ultrasonic transducer 100, and all of them do not have to be the same shape. In this embodiment, the shape of the piezoelectric material 130a divided by the first grooves 130b is a rectangular parallelepiped, but the shape of the piezoelectric material 130a divided by the first grooves 130b is not limited to a rectangular parallelepiped, and is not particularly limited as long as it is possible to oscillate ultrasonic waves in a desired direction.

[0028] The thickness of the piezoelectric material 130 is appropriately selected depending on the type of ultrasonic transducer and the frequency at which the ultrasonic transducer oscillates, and is, for example, 50 μm or more and 400 μm or less.

[0029] The width of each of the first grooves 130b in the piezoelectric material 130 is 15 to 45 μm. When the piezoelectric material 130a is not completely divided by the first grooves 130b, the depth of the first grooves 130b is preferably about 80 to 90% of the thickness of the piezoelectric material 130. 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, it is preferable that the total depth of the grooves including the first grooves 130b, the grooves (not shown) formed in the electrical terminal lead-out portion 120, and the grooves 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 groove 130b and a groove is also provided in the matching layer 140, it is preferable that the total depth of the grooves including the first groove 130b, the second groove 140d described below, the groove (not shown) formed in the electrical terminal outlet 120, and the groove formed in the backing material 110 is 10 to 100 μm longer than the thickness of the piezoelectric material 130a and the thickness of the matching layer to be cut. The interval between adjacent first grooves 130b is 150 to 600 μm, but can be changed as appropriate.

[0030] Examples of the piezoelectric material 130a include piezoelectric ceramics such as lead zirconate titanate (PZT) system; piezoelectric single crystals such as lead magnesium niobate-lead titanate solid solution (PMN-PT) and lead zinc niobate-lead titanate solid solution (PZN-PT); and composite piezoelectric materials combining these materials with polymeric materials.

[0031] Furthermore, the multiple signal electrodes 170a and 170b disposed on both sides of the piezoelectric material 130 are electrodes for applying a 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 above-mentioned electrical terminal outlet portion 120 and can sufficiently transmit and receive signals between the piezoelectric material 130, and can be layers made of, for example, gold, silver, copper, or the like.

[0032] (matching layer) The matching layer 140 is a layer disposed on the piezoelectric material 130 (in this embodiment, on the signal electrode 170b of the piezoelectric material 130a) and is a layer for matching acoustic characteristics between the piezoelectric material 130 and the acoustic lens 150. The matching layer 140 may be composed of a single layer, but is usually composed of multiple layers with different acoustic impedances. There is no particular limit to the number of layers in the matching layer, and typically two or more layers are used. 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.

[0033] The acoustic impedance of each layer constituting the matching layer 140 can be adjusted as appropriate depending on the components constituting each layer. For example, when each of the matching layers 140a, 140b, and 140c is a layer containing a resin and a filler, the acoustic impedance of each layer can be adjusted by adjusting the type and amount of the filler. Note that each of the matching layers 140a, 140b, and 140c may be a layer containing the same resin and the same filler, or may be a layer containing different resins and / or different fillers. Furthermore, the thickness of each layer may be the same or different.

[0034] The type of resin and the type of filler contained in the matching layer 140 are not particularly limited. Examples of the resin include epoxy resin. On the other hand, examples of the filler include inorganic fine particles such as ferrite; and organic fine particles such as silicone fine powder. In this embodiment, the composition of the third matching layer 140c is different from the composition of the filler 160 described below. However, the composition of the third matching layer 140c may be the same as the composition of the filler 160.

[0035] In this embodiment, the first matching layer 140a and the second matching layer 140b have a second groove 140d connected to the first groove 130b of the piezoelectric material 130 described above. The shape of the second groove 140d in plan view is the same as the shape of the first groove 130b in plan view. On the other hand, the top layer of the matching layer 140 closest to the acoustic lens 150 (the third matching layer 140c in this embodiment) does not have the second groove 140d. However, this is not limited to this embodiment, and the top layer (the third matching layer 140c) may have the second groove 140d. Also, the top layer may have a groove that communicates with only a part of the multiple second grooves 140d. In this case, the groove may be filled with the filler 160, may be a void, or may be filled with a filler having a composition different from that of the filler 160.

[0036] (acoustic lens) The acoustic lens 150 is a component for focusing ultrasonic waves transmitted from the piezoelectric material 130. As shown in Fig. 1, in this embodiment, the acoustic lens 150 is a cylindrical acoustic lens that extends in the Y direction in Fig. 1 and protrudes in the Z direction. The cross-sectional shapes perpendicular to the X direction are all the same. Furthermore, in the acoustic lens 150, ultrasonic waves oscillated by each piezoelectric material 130a are focused in the Z direction and emitted to the outside of the ultrasonic transducer 100.

[0037] The acoustic lens 150 is made of a material having acoustic properties suitable for an object to be inspected, such as a living body. For example, the acoustic lens 150 is preferably made of a material, such as silicone rubber, having an acoustic impedance relatively close to that of the object to be inspected.

[0038] (filling material) The filler 160 is a material filled in the first groove 130b of the piezoelectric material 130 described above, the second groove 140d of the matching layer 140, and the grooves of the backing material 110 and the electrical terminal outlet portion 120, and is a material for suppressing ultrasonic interference between adjacent piezoelectric materials 130a to increase the directionality of the ultrasonic transducer 100, increasing the strength of the ultrasonic transducer 100, and increasing the mechanical resistance to external impacts.

[0039] The filler 160 is preferably 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. However, there may be some voids if necessary. Furthermore, 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 a portion of the groove of the electrical terminal lead-out portion 120 may be filled with a filler having a composition different from that of the filler 160, which includes the epoxy resin and organic filler.

[0040] The filler 160 contains an epoxy resin and an organic filler having a cumulative percentage 10% value in a cumulative particle size distribution of 0.9 μm or more. In the filler 160, the epoxy resin acts as a binder, and the organic filler is dispersed in the binder.

[0041] 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, polycyclic aromatic type epoxy resins such as naphthalene structure-containing type, anthracene structure-containing type, and fluorene structure-containing type, hydrogenated alicyclic epoxy resins, liquid crystalline epoxy resins, etc. The filler 160 may contain only one type of epoxy resin, or may contain two or more types.

[0042] Among the above epoxy resins, from the viewpoint of chemical resistance, epoxy resins having a plurality of epoxy groups are preferred, and the number of epoxy groups in one molecule can be, for example, 3 to 4. Also, those having a high glass transition temperature (Tg) and those having a high crosslinking density are preferred. Therefore, among the above, novolac type epoxy resins are preferred.

[0043] 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, and even more preferably 40 parts by mass or more and 50 parts by mass or less, relative to 100 parts by mass of the total amount of the filler 160. When the ratio of the epoxy resin is 40 parts by mass or more, the strength of the ultrasonic transducer is increased. On the other hand, when the ratio of the epoxy resin is 60 parts by mass or less, the amount of the organic filler becomes relatively large, and the directionality of the ultrasonic transducer 100 becomes good.

[0044] On the other hand, the organic filler is not particularly limited as long as it contains an organic resin and is a particle having a predetermined particle size, but the organic filler is preferably an elastomer particle. Examples of the elastomer contained in the elastomer particles include silicone, urethane, acrylic, butadiene, etc.

[0045] 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, the durability (mechanical strength) of the ultrasonic transducer is maintained and excellent directivity is obtained.

[0046] The cumulative particle size distribution is calculated based on the results of measuring the particle diameters of about 200 particles using a scanning electron microscope (SEM). As a method for separating the organic filler from the filler composition before curing, a method is available in which the epoxy resin in the filler composition is dissolved or removed with an organic solvent such as ethanol, and only the organic filler is taken out. On the other hand, when measuring the cumulative particle size distribution from the filler 160, the ultrasonic transducer 100 is cut out along the Y direction using a dicing saw, diamond cutter, or the like, and the filler 160 is subjected to elemental analysis using energy dispersive X-ray analysis (EDS) or wavelength dispersive X-ray analysis (WDS). As a result, the elements derived from the organic filler (Si in the case of silicone) are mapped, and the organic filler is identified. Then, the particle diameter of the identified organic filler is measured using a scanning electron microscope (SEM), and the cumulative particle size distribution is calculated. The cumulative percentage 10% value refers to the particle diameter at a cumulative frequency of 10% from the smallest particle size side in the cumulative particle size distribution measured by the above method (hereinafter, referred to as "D 10 Furthermore, when the filling material 160 contains a plurality of organic fillers, the cumulative particle size distribution is measured with all of these mixed together.

[0047] In addition, in this 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 that small particles are easily filled between the large particles. As a result, the path of the ultrasonic wave transmitted from one piezoelectric material 130a to the adjacent piezoelectric material 130a is easily cut off. As a result, it becomes difficult for the ultrasonic wave to be transmitted between the adjacent piezoelectric materials 130a, and the directivity of the ultrasonic transducer 100 is easily increased.

[0048] As an index showing that the particle size distribution of the organic filler is broad, there are the 50% cumulative percentage value and the 90% cumulative percentage value in the cumulative particle size distribution. The larger the difference between the 50% cumulative percentage value and the 90% cumulative percentage value and the 10% cumulative percentage value, the broader the particle size distribution can be said to be. 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 is within the range, it becomes easier to obtain excellent directivity while maintaining the durability (strength) of the ultrasonic transducer.

[0049] Here, the filler 160 may contain only one type of organic filler, but preferably contains two or more types of organic fillers. When the filler 160 contains two or more types of organic fillers, it becomes easier to satisfy the above-mentioned 10% cumulative percentage, 50% cumulative percentage, and 90% cumulative percentage.

[0050] At least one of the organic fillers is preferably an organic filler having a structure capable of reacting with an epoxy resin (hereinafter, also referred to as a "reactive organic filler"). Here, the structure capable of reacting with an epoxy resin refers to an epoxy group, an amino group, or the like. When the filler 160 contains a reactive organic filler, the dispersibility of the organic filler in the filler 160 is improved, and the directionality of the ultrasonic transducer is improved. Whether the filler 160 contains a reactive organic filler, that is, whether the organic filler has a structure capable of reacting with an epoxy resin, can be confirmed by observing a cross section of the filler 160 using a scanning electron microscope (SEM) or the like. 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 confirmed. On the other hand, when the filler 160 does not have a structure capable of reacting with an epoxy resin, a gap is confirmed between the epoxy resin and the filler.

[0051] The filler 160 may contain only one type of reactive organic filler, or may contain two or more types.

[0052] 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. The average particle size is measured by a scanning electron microscope. On the other hand, if the average particle size of the reactive organic filler is 1.2 μm or more, it is easy to satisfy the above-mentioned cumulative particle size distribution.

[0053] The amount of 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 even more preferably 10 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the total amount of the organic filler. When the amount 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 amount of the reactive organic filler is 30 parts by mass or less, the viscosity of the filler composition when preparing the filler 160 does not increase excessively, and the above-mentioned first groove 130b, second groove 140d, etc. can be filled without gaps.

[0054] As described above, since the reactive organic filler has a high affinity with the binder resin, if a large amount is used, it may become difficult to fill the first grooves 130b etc. with the filler 160. Therefore, it is preferable that the organic filler contains, together with the reactive organic filler, a filler that is not reactive with the epoxy resin and has a particle size different from that of the reactive organic filler (hereinafter, also referred to as a "non-reactive organic filler").

[0055] Examples of the non-reactive organic filler include silicone particles, urethane particles, acrylic particles, butadiene, etc. Among these, silicone particles are particularly preferred from the viewpoint of maintaining the elastic modulus of rubber even at low temperatures. The filler 160 may contain only one type of non-reactive organic filler, or may contain two or more types.

[0056] The particle size 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. The average particle size is measured by a scanning electron microscope. If the average particle size of the non-reactive organic filler is 2.0 μm or more, it is easy to satisfy the above-mentioned cumulative particle size distribution.

[0057] 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 even more preferably 80 parts by mass or more and 90 parts by mass or less, relative to 100 parts by mass of the total amount of the organic filler. When the ratio of the non-reactive organic filler is 90 parts by mass or more, the viscosity of the filler composition when preparing the filler 160 does not increase excessively, and the filler 160 can be easily formed without gaps in the above-mentioned first groove 130b and second groove 140d. 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 becomes sufficiently large, and the organic filler is easily dispersed uniformly in the filler 160.

[0058] The content (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 even more preferably 50 parts by mass or more and 60 parts by mass or less, relative to 100 parts by mass of the filler. When the content of the organic filler is 60 parts by mass or more, the directionality of the ultrasonic transducer 100 is increased. On the other hand, when the content of the organic filler is 40 parts by mass or less, the content of the epoxy resin becomes sufficiently high, and the strength of the ultrasonic transducer 100 is increased.

[0059] In addition to the epoxy resin and organic filler, the filler 160 may contain other components as necessary within the scope of the purpose and effect of the present invention. Examples of other components include a coupling agent. When the filler 160 contains a coupling agent, the dispersibility of the non-reactive organic filler described above is improved. Examples of coupling agents include a silane coupling agent containing an epoxy group or an amino group, a titanium coupling agent, and the like.

[0060] The coupling agent may be a commercially available product, and examples thereof include A-186, A-187, A-1871, A-1100, A-1110, A-1120, A-2120, and Y-9669 (all trade names, manufactured by Momentive Corporation); KBM-602, KBM-603, KBM-903, KBE-903, KBE-9103P, KBM-573, KBM-575, KBM-303, KBM-402, KBM-403, KBE-402, and KBE-403 (all 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, and XIAMETER OFS-6032. Silane, DOWSIL Z-6269 Silane, DOWSIL SZ 6032 Silane, XIAMETER OFS-6040 Silane, DOWSIL Z-6044 Silane, DOWSIL Z-6043 Silane (all trade names, DOWSIL and XIAMETER are registered trademarks, manufactured by Dow Corning Toray); S310, S320, S330, S340, S350, S510, S530 (all trade names, manufactured by JNC Corporation); and PLENACT amino group-containing 44 (manufactured by Ajinomoto Fine-Techno Co., Ltd.).

[0061] Furthermore, the filler 160 may contain a small amount of inorganic particles, but the amount of inorganic particles is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, relative to 100 parts by mass of the total amount of the filler 160. When the amount of inorganic particles in the filler 160 is 1 part by mass or less, the amount of epoxy resin and organic filler becomes relatively sufficient, making it easier to obtain the polarity and directionality described above.

[0062] (Method of manufacturing ultrasonic transducer) The method for manufacturing the ultrasonic transducer described above is not particularly limited as long as it can form the above-mentioned structure. An example is shown below, but the method is not limited to this method.

[0063] In this manufacturing method, a backing material without a groove, a flat-plate-shaped electrical terminal lead-out portion without a groove, and a flat-plate-shaped piezoelectric material having signal electrodes formed on both sides and no first groove are bonded together (bonding process). Then, a matching layer is formed on the piezoelectric material (signal electrodes) (matching layer forming process), and multiple grooves are formed from the matching layer side toward the backing material (groove forming process). After that, the grooves formed in the groove forming process are filled with a filler composition and cured (filler forming process), and an acoustic lens is attached onto the matching layer (acoustic lens attaching process). If necessary, other processes may be included.

[0064] · Bonding process In the lamination step, a flat backing material without a groove, an electric terminal lead-out part having a desired circuit or the like arranged on a single film without a groove, and a flat piezoelectric material having signal electrodes formed on both sides and having no first groove are laminated together. The order of lamination is not particularly limited, and the backing material and the electric terminal lead-out part may be laminated first, or the piezoelectric material and the electric terminal lead-out part may be laminated together. The method of lamination is not particularly limited, and for example, they may be bonded with an adhesive or the like.

[0065] The method of forming the signal electrodes on the surface of the piezoelectric material is not particularly limited, and may be, for example, formed by evaporating or sputtering gold or silver, etc., or by baking silver onto the piezoelectric material, or by attaching a conductor such as copper to the piezoelectric material and patterning it.

[0066] ·Matching layer formation process In the matching layer forming step, a matching layer is formed on the piezoelectric material (here, one of the signal electrodes). The method of forming the matching layer is not particularly limited, and previously prepared matching layers may be attached one by one, or multiple matching layers may be previously stacked and then attached to the piezoelectric material. Furthermore, the step of applying a matching layer composition onto the piezoelectric material and curing it may be repeated. The matching layer formed in the matching layer forming step does not have a second groove.

[0067] Although the entire matching layer may be formed in the matching layer forming step, when the second groove is provided only in a part of the matching layer, only the matching layer in which the groove is provided is formed.

[0068] ·Groove formation process In the groove forming step, grooves are formed from the matching layer side to the backing material. The method of forming the grooves is not particularly limited, and is appropriately selected depending on the width of the first groove and the second groove, the thickness of the piezoelectric material, etc. For example, cutting may be performed with a dicing saw or a diamond cutter, or cutting may be performed by Micro Electro Mechanical Systems (MEMS) processing.

[0069] ·Filling material formation process In the filler filling step, a filler composition is introduced into the groove formed in the above-mentioned groove forming step and hardened. At this time, in addition to filling the groove with the filler composition, the filler composition may be applied to the above-mentioned matching layer and hardened to form a part of the matching layer (for example, the above-mentioned third matching layer 140c). In this case, the matching layer formed in the filler forming step (for example, the above-mentioned third matching layer 140c) does not have the second groove 140d.

[0070] The method for filling the grooves with the filler composition is not particularly limited, and for example, the filler composition may be injected with a spatula, etc. Furthermore, the method for forming the filler composition on the matching layer is also not particularly limited, and for example, the filler composition may be applied with a spatula, etc., which is used when injecting the filler composition into the grooves.

[0071] The filler composition is a composition containing the above-mentioned epoxy resin precursor (hereinafter also referred to as "prepolymer"), the above-mentioned organic filler, and, if necessary, a curing agent, a coupling agent, etc.

[0072] Examples of the prepolymer include the above-mentioned epoxy resin monomers and oligomers, etc. The organic filler and coupling agent are the same as those described above.

[0073] On the other hand, examples of curing agents for curing the prepolymer include triazine compounds such as ethylenediamine, triethylenediamine, hexamethylenediamine, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine; 1,8-diazabicyclo[5,4,0]undecene-7 (DBU); triethylenediamine; benzyldimethylamine; triethanolamine; linear aliphatic polyamines; aliphatic polyamines such as cyclic aliphatic polyamines and aliphatic aromatic polyamines; aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone; and modified amines such as amine adducts and ketimines.

[0074] Examples of the above-mentioned chain aliphatic polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine and diethylaminopropylamine.

[0075] Examples of the cycloaliphatic polyamines include N-aminoethylpiperazine, Lamiron C-260, Araldit HY-964, menthene diamine, isophorone diamine, SCure 211, SCure 212, Wondamin HM, and 1.3BAC (all manufactured by Three Bond Co., Ltd.).

[0076] Examples of the aliphatic aromatic polyamines include m-xylylenediamine, Shawamine X, Amine Black, Shawamine Black, Shawamine N, Shawamine 1001 and Shawamine 1010 (all manufactured by ThreeBond Co., Ltd.).

[0077] The method for curing the filler composition is appropriately selected depending on the type of curing agent in the filler composition, but it is usually preferable to solidify the composition by heating. The heating temperature is appropriately selected. Heating can be performed by a known method, for example, by using a heater or a thermostatic bath.

[0078] Acoustic lens attachment process After the filling material forming step, an acoustic lens is attached onto the matching layer. There are no particular limitations on the method for attaching the acoustic lens, and it can be attached, for example, by an adhesive or the like.

[0079] 2. Ultrasound probe and ultrasound diagnostic device The above-mentioned ultrasonic transducer can be used in, for example, an ultrasonic probe 100a or an ultrasonic diagnostic device 10 as shown in Fig. 3. The ultrasonic diagnostic device 10 includes an ultrasonic probe 100a having the above-mentioned ultrasonic transducer, a main body 11, a connector 12, a display 13, and the like.

[0080] The ultrasonic probe 100a is only required to include the ultrasonic transducer (not shown) described above, and is connected to the main body 11 via a cable 14 connected to a connector section 12.

[0081] An electric signal (transmission signal) from the main body 11 is transmitted to the piezoelectric material of the ultrasonic probe 100a through the cable 14. This transmission signal is converted into ultrasonic waves by the piezoelectric material and transmitted into the object to be inspected. The transmitted ultrasonic waves are reflected within the object to be inspected. A part of the reflected waves is then 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 body 11 of the ultrasonic diagnostic device 10 and displayed on the display 13.

[0082] The ultrasonic diagnostic device equipped with the ultrasonic transducer of the above embodiment has high directivity and can perform accurate diagnosis. Furthermore, the ultrasonic transducer has high strength and can withstand impacts such as dropping, so it can be used in ultrasonic diagnostic devices in various fields. EXAMPLES

[0083] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these.

[0084] 1. Fabrication of Ultrasound Transducer Comparative Example 1 A backing material and a flexible printed circuit board (electrical terminal extraction part) were attached in that order on top of the fixed plate with adhesive. A piezoelectric material made of lead zirconate titanate (PZT) measuring 4.6 mm x 42.5 mm with signal electrodes arranged on both sides was also prepared. The piezoelectric material and the flexible printed circuit board were then bonded together so that one of the signal electrodes was adjacent to the flexible printed circuit board.

[0085] Next, a dicing saw was used to create grooves perpendicular to the laminated surfaces of the piezoelectric material and the flexible printed circuit board. The piezoelectric material was formed by forming multiple grooves so that they were parallel when viewed in a plan view and were positioned at equal intervals. The width of the groove was 20 μm. The depth of the groove was adjusted so that the backing material was not completely cut.

[0086] Next, a filler composition was prepared as follows: Epoxy resin 1 (trade name: C1163A, manufactured by Tesque), organic filler-containing epoxy resin 2 (trade name: EP2240, manufactured by Evonik (organic filler surface contains a structure capable of reacting with epoxy resin), filler particle size: 0.1 to 3 μm), amine-based curing agent 1 (trade name: C1163B, manufactured by Tesque), and amine-based curing agent 2 (trade name: ST12, manufactured by Mitsubishi Chemical) were mixed in a mass ratio of 33:37:17:13.

[0087] The filler composition was then applied onto the piezoelectric material with a spatula, and vacuum degassed for 3 minutes. Three matching layers (first matching layer, second matching layer, and third matching layer) were formed on the signal electrode of the piezoelectric material. Each matching layer was a cured product of a mixture of epoxy resin and ferrite or silicone fine powder. After heating at 60°C for 4 hours, an acoustic lens was bonded onto the third matching layer with an adhesive to obtain the ultrasonic transducer 1.

[0088] The above filler composition was put into ethanol, the epoxy resin in the filler composition was removed, and only the organic filler was taken out.Then, the particle diameter of about 200 particles of the organic filler was measured by 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, and it was 0.4 μm.

[0089] Comparative Example 2 A backing material and a flexible printed circuit board (electrical terminal extraction portion) were adhered in this order on the fixed plate with an adhesive. A piezoelectric material made of lead zirconate titanate (PZT) measuring 4.6 mm x 42.5 mm and having signal electrodes on both sides was prepared. The piezoelectric material and the flexible printed circuit board were then adhered together so that one of the signal electrodes was adjacent to the flexible printed circuit board. As in Comparative Example 1, two matching layers (first matching layer and second matching layer) were formed on the signal electrodes of the piezoelectric material.

[0090] Next, a dicing saw was used to make grooves perpendicular to the lamination surface of each component in the matching layers (first matching layer and second matching layer), the piezoelectric material layer, and the flexible printed circuit board. The grooves were formed so that they were parallel when viewed in a plane and were positioned at equal intervals. The groove width was 20 μm. The depth of the groove was adjusted so that the backing material was not completely cut.

[0091] Next, a filler composition was prepared as follows: Silicone resin (product name: KE-1604, manufactured by Shin-Etsu Chemical Co., Ltd.) and amine-based curing agent 3 (product name: CAT1604, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed in a mass ratio of 90:10.

[0092] The groove was filled with the filler composition by applying with a spatula and vacuum degassing for 3 minutes. A third matching layer was then attached and heated at 60°C for 2 hours. After that, an acoustic lens was attached with an adhesive onto the matching layer (third matching layer) to obtain an ultrasonic transducer 2.

[0093] Comparative Example 3 The filler composition was prepared by mixing epoxy resin 1 (product name: C1163A, manufactured by Tesque), organic filler-containing epoxy resin 2 (product name: EP2240, manufactured by Evonik (the organic filler surface contains a structure capable of reacting with epoxy resin)), amine-based curing agent 1 (product name: C1163B, manufactured by Tesque), and amine-based curing agent 2 (product name: ST12, manufactured by Mitsubishi Chemical Corporation) in a mass ratio of 33:37:17:13, and heating the mixture at 60°C for 4 hours. Except for this, ultrasonic transducer 3 was obtained in the same manner as in Comparative Example 2.

[0094] In the same manner as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and extracted, and the 10% cumulative percentage value in the cumulative particle size distribution of the organic filler was determined by a scanning electron microscope (SEM) in the same manner as in Comparative Example 1, and was found to be 0.4 μm. Comparative Example 4 A filler composition was prepared by adding 30 parts by mass of tungsten trioxide powder to 100 parts by mass of the filler composition of Comparative Example 3, and ultrasonic transducer 4 was produced in the same manner as in Comparative Example 2, except that the filler composition was heated at 60°C for 4 hours.

[0095] In the same manner as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and extracted, and the 10% cumulative percentage value in the cumulative particle size distribution of the organic filler was measured using a scanning electron microscope (SEM) in the same manner as in Comparative Example 1, and was found to be 0.4 μm.

[0096] Comparative Example 5 A filler composition was prepared by adding 50 parts by mass of silicone composite powder (product name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd., particle size: 0.7 to 5 μm) to 100 parts by mass of the filler composition of Comparative Example 3. The ultrasonic transducer 5 was produced in the same manner as in Comparative Example 2, except that the filler composition was heated at 60°C for 4 hours.

[0097] In the same manner as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and extracted, and the 10% cumulative percentage value in the cumulative particle size distribution of the organic filler was measured using a scanning electron microscope (SEM) in the same manner as in Comparative Example 1, and was found to be 0.8 μm.

[0098] Example 1 A filler composition was prepared by adding 75 parts by mass of silicone composite powder (product name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd., particle size: 0.7 to 5 μm) to 100 parts by mass of the filler composition of Comparative Example 3. The ultrasonic transducer 6 was produced in the same manner as in Comparative Example 2, except that the filler composition was heated at 60°C for 4 hours.

[0099] Using the same method as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and extracted, and the 10% cumulative percentage value in the cumulative particle size distribution of the organic filler was measured using a scanning electron microscope (SEM) using the same method as in Comparative Example 1, and was found to be 0.9 μm.

[0100] Example 2 An ultrasonic transducer 7 was produced in the same manner as in Comparative Example 2, except that a filler composition was prepared by adding 100 parts by mass of silicone composite powder (product name: KMP-605, manufactured by Shin-Etsu Chemical Co., Ltd., particle size: 0.7 to 5 μm) to 100 parts by mass of the filler composition of Comparative Example 3, and heating the composition at 60° C. for 4 hours.

[0101] Using the same method as in Comparative Example 1, only the organic filler in the obtained filler was diluted with an organic solvent and extracted, and the 10% cumulative percentage value in the cumulative particle size distribution of the organic filler was measured using a scanning electron microscope (SEM) using the same method as in Comparative Example 1, and was found to be 1.0 μm.

[0102] 2. Evaluation The directivity and intensity of each of the ultrasonic transducers were evaluated by the following methods. The results are shown in Table 1.

[0103] (1) Directivity evaluation method An ultrasonic probe including the ultrasonic transducer described above was placed near the water surface of the tank in which the spherical target was placed. A pulser receiver and an oscilloscope were electrically connected to the ultrasonic probe. The pulser receiver was an ultrasonic pulser receiver: MODEL5900PR manufactured by Olympus, and the oscilloscope was an oscilloscope: TDS5032 manufactured by TFF.

[0104] Then, ultrasonic waves were transmitted from the probe head of the ultrasonic probe immersed in water toward a spherical target, and the reflected waves were received to determine the directivity of the ultrasonic probe. The directivity was evaluated when the angles between the spherical target and the element in the ultrasonic probe to be measured were set to -40°, -30°, -20°, -10°, 0°, +10°, +20°, +30°, and +40°, specifically, the presence or absence of ripples in the transmission and reception frequency characteristics at each angle. The case where the spherical target and the element in the ultrasonic probe to be measured are located on a straight line was set as 0°. The evaluation was based on the following criteria. (Evaluation Criteria) ○: The maximum sensitivity S 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° MAX and the minimum sensitivity S of the ripple part MIN The absolute value of the difference ΔS is less than 10 dB. △: The maximum sensitivity S 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° MAX and the minimum sensitivity S of the ripple part MIN The absolute value of the difference ΔS is 10 dB or more and less than 20 dB. ×: The maximum sensitivity S 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° MAX and the minimum sensitivity S of the ripple part MIN The absolute value of the difference ΔS is 20 dB or more.

[0105] (2) Drop test evaluation method An ultrasonic probe having the ultrasonic transducer described above was prepared. A weight with a steel ball at the tip and the same weight as the ultrasonic probe (excluding the cable and connector) was dropped onto the top surface of the acoustic lens of the ultrasonic probe. The weight was dropped from a height 10 cm higher than the acoustic lens, and was 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) ○: When there is no element with an ultrasonic transducer whose capacitance Sa after a weight is dropped from a height of 122 cm is compared with the capacitance Sb before the test, the difference Sa-Sb = ΔSc is -5 pF or less. ×: When the capacitance Sa of the ultrasonic transducer after a weight is dropped from a height of 122 cm is compared with the capacitance Sb before the test, the difference Sa-Sb=ΔSc is -5 pF or less for one or more channels.

[0106] 3.Results [Table 1]

[0107] As shown in Table 1 above, the piezoelectric material has grooves (first grooves) that separate the piezoelectric materials, and the grooves contain epoxy resin and organic filler. Furthermore, the cumulative percentage 10% value (D 10 ) was 0.9 μm or more, the directionality of the ultrasonic waves was good, and the results of the drop test were also good (Examples 1 and 2).

[0108] On the other hand, even if the filler contains organic fillers, the cumulative percentage in the cumulative particle size distribution is 10% (D 10 ) was less than 0.9 μm, the directionality was likely to be low (Comparative Examples 1, 3 to 5). Also, when the filler was a silicone resin not containing an organic filler, the directionality was good, but the drop test results were low (Comparative Example 2). [Industrial Applicability]

[0109] The ultrasonic transducer of the present invention has high mechanical strength and excellent directionality, and is therefore useful for various ultrasonic diagnostic devices and the like. [Explanation of symbols]

[0110] 10. Ultrasound diagnostic equipment 11 Main body 12 Connector part 13. Display 14 Cable 100 Ultrasonic Transducer 100a Ultrasound Probe 110 Backing material 120 Electrode terminal outlet 130 Piezoelectric material 130a Piezoelectric materials 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 Filling material 170a, 170b signal electrode

Claims

1. A piezoelectric material including a piezoelectric material; at least one matching layer disposed on the piezoelectric material; An ultrasonic transducer comprising: the piezoelectric material further comprises at least one first groove dividing the piezoelectric material into a plurality of regions; The width of the first groove is 15 to 45 μm; the first groove of the piezoelectric material is filled with a filler including an epoxy resin and an organic filler; The organic filler is an elastomer particle, and includes a reactive organic filler having a particle size of 0.1 to 3 μm and a non-reactive organic filler having a particle size of 0.7 to 10.0 μm; The total amount of the organic filler is 50 parts by mass or more and 60 parts by mass or less relative to 100 parts by mass of the filler, The 10% cumulative percentage in the cumulative particle size distribution of the organic filler is 0.9 μm or more; Ultrasonic transducer.

2. the matching layer has a second groove connected to the first groove in the piezoelectric material; The second groove is filled with the filler.

2. The ultrasonic transducer of claim 1.

3. the matching layer is a stack of multiple layers, and a top layer of the multiple layers does not have the second groove; 3. The ultrasonic transducer according to claim 2.

4. The composition of the top layer is the same as the composition of the filler.

4. The ultrasonic transducer according to claim 3.

5. 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 to 4.

6. the reactive 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 to 5.

7. The filler comprises a coupling agent. The ultrasonic transducer according to any one of claims 1 to 6.

8. A method comprising the steps of: Ultrasound probe.

9. The ultrasonic probe according to claim 8, Ultrasound diagnostic equipment.

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