Ultrasonic probe, ultrasonic diagnostic device, and method for manufacturing ultrasonic probe

Abstract

The present invention provides an ultrasonic probe adaptive to high-frequency driving, a method for manufacturing the ultrasonic probe, and an ultrasonic diagnosis device.　An ultrasonic probe (100) is provided with an acoustic matching part (20) disposed on a plurality of piezoelectric elements (10), and a conductive member (30Fr) disposed on the plurality of piezoelectric elements (10) adjacently to the acoustic matching part (20). The conductive member (30Fr) includes a conductor layer having a multilayer structure, the conductor layer being disposed on the front-side of the acoustic matching part (20) in a front-rear direction FR. This conductor layer having a multilayer structure includes a plurality of first conductor layers (32F) respectively joined to second conductive parts (13) of the piezoelectric elements (10), and a second conductor layer (31F) laminated on the plurality of first conductor layers (32F) and electrically connecting the plurality of first conductor layers (32F). Regarding the first conductor layers (32F), the ratio of the thickness HF in the up-down direction UD to the width D1 in the left-right direction LR is less than or equal to 1.6.

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic probe, an ultrasonic diagnostic device, and a method for manufacturing an ultrasonic probe. [Background technology]

[0002] In the medical field, ultrasound diagnostic devices using ultrasound images have been put to practical use. This type of ultrasound diagnostic device transmits an ultrasound beam from an ultrasound probe toward a subject, receives ultrasound echoes from the subject with the ultrasound probe, and generates an ultrasound image by electrically processing the received signals.

[0003] In the field of ultrasound diagnosis, the need for ever higher-resolution ultrasound images is increasing as the range of objects to be observed expands. Acquiring high-resolution ultrasound images requires the transmission and reception of high-frequency ultrasound, but unless the element pitch of the piezoelectric elements is made fine enough to match the ultrasound frequency, grating lobes will occur, affecting the quality of the ultrasound images.

[0004] Patent Document 1 describes an ultrasonic probe that aims to suppress a decrease in sensitivity when the element pitch of the piezoelectric elements is made finer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 070159 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 states that when the driving frequency of the piezoelectric element exceeds 15 MHz, it is preferable that the element pitch be 150 μm or less, but does not mention driving at higher frequencies.

[0007] An object of the present invention is to provide an ultrasonic probe that can be driven at high frequencies, a method for manufacturing the same, and an ultrasonic diagnostic apparatus. [Means for solving the problem]

[0008] An ultrasonic probe according to one embodiment of the present invention is an ultrasonic probe having a plurality of piezoelectric elements arranged in a first direction, and comprises: a support member supporting the plurality of piezoelectric elements; an acoustic matching unit arranged on the plurality of piezoelectric elements; and a conductive member arranged on the plurality of piezoelectric elements adjacent to the acoustic matching unit, wherein the plurality of piezoelectric elements are each formed as a laminate in which a first conductive portion, a piezoelectric portion, and a second conductive portion are sequentially stacked above the support member, and the conductive member includes a multi-layered conductive layer arranged on at least one end side of the acoustic matching unit in a second direction that intersects with the first direction, and the multi-layered conductive layer includes a plurality of first conductive layers respectively joined to the second conductive portions of the piezoelectric elements, and a second conductive layer stacked on the plurality of first conductive layers and electrically connecting the plurality of first conductive layers, and the ratio of the thickness to the width, which is the length in the first direction, of the first conductive layer is 1.6 or less.

[0009] An ultrasonic diagnostic apparatus according to one aspect of the present invention includes the ultrasonic probe described above.

[0010] A method for manufacturing an ultrasonic probe according to one aspect of the present invention includes a plurality of piezoelectric elements arranged in a first direction, and the piezoelectric elements have a width, which is a length in the first direction, of a predetermined value. The method includes a step of fixing a sheet-like laminate, which is perpendicular to the third direction and in which a first conductive portion, a piezoelectric portion, and a second conductive portion are sequentially laminated, to a support member; and a step of fixing a sheet-like laminate, which is perpendicular to the third direction and in which a first conductive portion, a piezoelectric portion, and a second conductive portion are sequentially laminated, to a support member. forming an acoustic matching portion in a partial region of the upper surface of the laminate; forming a first conductor layer on at least one end side in the second direction of the acoustic matching portion on the upper surface of the laminate, the first conductor layer having a thickness in the third direction that is 1.6 times or less the predetermined value; dividing the laminate on which the acoustic matching portion and the first conductor layer are formed into a plurality of pieces in the first direction by cutting to form the plurality of piezoelectric elements; and forming a second conductor layer on the divided first conductor layers so as to span the plurality of first conductor layers. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an ultrasonic probe that can be driven at high frequencies, a method for manufacturing the same, and an ultrasonic diagnostic apparatus. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic plan view showing a general configuration of an ultrasonic probe 100 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG. [Figure 3] 2 is a schematic cross-sectional view taken along the arrows BB and CC in FIG. 1. [Figure 4] FIG. 2 is a cross-sectional schematic view taken along the arrow DD in FIG. 1. [Figure 5] FIG. 2 is a schematic plan view showing the state after the first step is completed. [Figure 6] FIG. 6 is a schematic cross-sectional view taken along the line A1-A1 in FIG. 5. [Figure 7]6A and 6B are cross-sectional schematic views taken along the arrows A2-A2 and A3-A3 in FIG. 5. [Figure 8] FIG. 10 is a schematic plan view showing the state after completion of the second step that follows the first step. [Figure 9] FIG. 9 is a schematic cross-sectional view taken along the line A1-A1 in FIG. 8. [Figure 10] FIG. 9 is a cross-sectional view taken along the line A4-A4 in FIG. 8. [Figure 11] FIG. 10 is a schematic plan view showing the state after completion of the third step that follows the second step. [Figure 12] FIG. 12 is a schematic cross-sectional view taken along the line A1-A1 in FIG. [Figure 13] 12A and 12B are cross-sectional schematic views taken along the arrows A2-A2 and A3-A3 in FIG. 11. [Figure 14] FIG. 10 is a schematic plan view showing the state after the fourth step, which is the next step after the third step, is completed. [Figure 15] 15A and 15B are cross-sectional schematic views taken along the arrows A2-A2 and A3-A3 in FIG. 14. [Figure 16] FIG. 15 is a schematic cross-sectional view taken along the line A4-A4 in FIG. [Figure 17] FIG. 10 is a schematic plan view showing the state after completion of the fifth step, which is the next step after the fourth step. [Figure 18] 18A and 18B are cross-sectional schematic views taken along the arrows A2-A2 and A3-A3 in FIG. 17. [Figure 19] FIG. 18 is a schematic cross-sectional view taken along the line A4-A4 in FIG. [Figure 20] FIG. 10 is a schematic plan view showing the state after the seventh step, which is performed after the fifth step, is completed. [Figure 21] FIG. 2 is a diagram showing a first modified example of the ultrasonic probe 100, and is a cross-sectional schematic diagram corresponding to the cross section taken along the arrow AA in FIG. [Figure 22] FIG. 2 is a diagram showing a second modified example of the ultrasonic probe 100, and is a cross-sectional schematic diagram corresponding to the cross section taken along the arrow AA in FIG. [Figure 23] FIG. 10 is a diagram showing the verification results of an ultrasonic probe. DETAILED DESCRIPTION OF THE INVENTION

[0013] FIG. 1 is a schematic plan view showing the general configuration of an ultrasonic probe 100, which is one embodiment of the ultrasonic probe of the present invention. FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG. 1. FIG. 3 is a schematic cross-sectional view taken along the line BB and CC in FIG. 1. FIG. 4 is a schematic cross-sectional view taken along the line DD in FIG. 1. The ultrasonic probe 100 is an image generating device included in an ultrasonic diagnostic apparatus. Ultrasonic diagnostic apparatuses include a device that generates and records ultrasonic images while bringing the ultrasonic probe 100 close to the outer surface of a subject, and a device that generates and records ultrasonic images while bringing the ultrasonic probe 100, which is built into the tip of an insertion portion of an endoscope, close to an organ of the subject.

[0014] In this specification, the right direction of the paper in Fig. 1 is referred to as the forward direction Fr of the ultrasonic probe 100, and the left direction of the paper in Fig. 1 is referred to as the rearward direction Rr of the ultrasonic probe 100, and these are collectively referred to as the front-rear direction FR. The upward direction of the paper in Fig. 1 is referred to as the rightward direction R of the ultrasonic probe 100, and the downward direction of the paper in Fig. 1 is referred to as the leftward direction L of the ultrasonic probe 100, and these are collectively referred to as the left-right direction LR. The direction perpendicular to the front-rear direction FR and the left-right direction LR is referred to as the up-down direction UD. Of the up-down directions UD, the direction from the front to the back of the paper in Fig. 1 is referred to as the downward direction D of the ultrasonic probe 100, and the direction from the back to the front of the paper in Fig. 1 is referred to as the upward direction U of the ultrasonic probe 100.

[0015] [Overall configuration of the ultrasound probe] The ultrasonic probe 100 includes a backing material 50, a front FPC (Flexible Printed Circuits) 60Fr and a rear FPC 60Rr (see FIG. 1) supported by the backing material 50, a plurality of (eight in the example of FIG. 1) piezoelectric elements 10 (see FIGS. 3 and 4) supported by the backing material 50 and arranged in the left-right direction LR, an acoustic matching section 20 (see FIG. 4) provided on each of the piezoelectric elements 10, a first conductive layer 32F and a first conductive layer 32R (see FIG. 3) provided on each of the piezoelectric elements 10, and a second conductive layer 31F and a second conductive layer 31R (see FIGS. 1 and 3) provided in common to all of the piezoelectric elements 10. The first conductive layer 32F, the first conductive layer 32R, the second conductive layer 31F, and the second conductive layer 31R are each made of a conductive material such as a metal or a metal compound.

[0016] 1 and 2, the front-side FPC 60Fr and the rear-side FPC 60Rr are aligned at a distance in the front-rear direction FR and fixed to the backing material 50 with an adhesive Ad such as epoxy resin. As shown in Fig. 1, an electrode pattern formation region 61Fr is provided at the rear end of the front-side FPC 60Fr. Also, an electrode pattern formation region 61Rr is provided at the front end of the rear-side FPC 60Rr.

[0017] As shown in the CC cross section of Fig. 3, in the electrode pattern forming region 61Fr, line electrodes 72 corresponding to each piezoelectric element 10 are arranged in the left-right direction LR. Also, as shown in the BB cross section of Fig. 3, in the electrode pattern forming region 61Rr, line electrodes 71 corresponding to each piezoelectric element 10 are arranged in the left-right direction LR.

[0018] As shown in FIGS. 3 and 4 , multiple piezoelectric elements 10 are arranged in the left-right direction LR above a backing material 50 at a predetermined arrangement pitch P. Each piezoelectric element 10 is configured as a laminate in which a first conductive portion 12 made of a conductive material, a piezoelectric body portion 11 made of a piezoelectric material, and a second conductive portion 13 made of a conductive material are sequentially stacked above the backing material 50. The first conductive portion 12 is fixed to the surface (lower surface) of the piezoelectric body portion 11 facing the backing material 50 by vapor deposition or the like, and the second conductive portion 13 is fixed to the surface (upper surface) of the piezoelectric body portion 11 opposite the backing material 50 by vapor deposition or the like. The first conductive portion 12 functions as a signal electrode of the piezoelectric element 10. The second conductive portion 13 functions as a ground electrode for obtaining a reference potential relative to the potential of the first conductive portion 12.

[0019] 2 and 3 , the first conductive portion 12 of the piezoelectric element 10 is disposed above the line electrodes 71 and 72 corresponding to the piezoelectric element 10 and is electrically connected to the line electrodes 71 and 72 by a conductive material (not shown) such as silver. The front FPC 60Fr and the rear FPC 60Rr are provided with connectors (not shown) connected to the line electrodes 71 and 72, and these connectors are electrically connected to the main body of the ultrasonic diagnostic device. Therefore, the potential of the first conductive portion 12 of the piezoelectric element 10 can be controlled or acquired from the main body of the ultrasonic diagnostic device via the line electrodes 71 and 72.

[0020] As shown in FIG. 2, the acoustic matching section 20, the first conductive layer 32F, and the first conductive layer 32R are disposed on the second conductive section 13 of the corresponding piezoelectric element 10. The acoustic matching section 20 is fixed onto the second conductive section 13 by adhesive or the like. The first conductive layer 32F is disposed adjacent to the acoustic matching section 20 on the front side thereof. The first conductive layer 32R is disposed adjacent to the acoustic matching section 20 on the rear side thereof. The first conductive layer 32F and the first conductive layer 32R corresponding to each piezoelectric element 10 are electrically connected to the second conductive section 13 of that piezoelectric element 10 and function as ground electrodes.

[0021] A portion including the piezoelectric element 10, the corresponding acoustic matching portion 20, the first conductive layer 32F, and the first conductive layer 32R will be referred to as a sensing unit. Gaps are formed between the sensing unit and adjacent sensing units, and these sensing units are separated from each other via these gaps. As shown in Figures 3 and 4, the gaps between adjacent sensing units are filled with insulating filler 40, which fixes the positions of the multiple sensing units.

[0022] The width D1 of the detection unit in the left-right direction LR is uniform across the up-down direction UD. In other words, the widths in the left-right direction LR of the piezoelectric elements 10, acoustic matching section 20, first conductive layer 32F, and first conductive layer 32R that make up the detection unit are all the same. The width D2 of the insulating filler 40 in the left-right direction LR is uniform across the up-down direction UD. The sum of widths D1 and D2 is the arrangement pitch P of the multiple piezoelectric elements 10. From the perspective of obtaining high-resolution ultrasonic images and suppressing the occurrence of grating noise, it is effective to make this arrangement pitch P small.

[0023] 1 and 3, the second conductive layer 31F has a long, narrow rectangular shape extending in the left-right direction LR, and is disposed on top of the first conductive layers 32F disposed on each of the piezoelectric elements 10, straddling these eight first conductive layers 32F. In other words, the second conductive layer 31F is electrically connected to the first conductive layers 32F corresponding to each of the piezoelectric elements 10, and functions as a ground electrode.

[0024] 1 and 3, the second conductive layer 31R has a long, narrow rectangular shape extending in the left-right direction LR, and is disposed on top of the first conductive layers 32R disposed on each of the piezoelectric elements 10, straddling these eight first conductive layers 32R. That is, the second conductive layer 31R is electrically connected to the first conductive layer 32R corresponding to each of the piezoelectric elements 10, and functions as a ground electrode. The second conductive layer 31F and the second conductive layer 31R are connected to the ground (not shown).

[0025] 1 and 2, the first conductive layer 32F corresponding to the piezoelectric element 10 and the second conductive layer 31F disposed on this first conductive layer 32F constitute a multi-layer conductive member 30Fr disposed on the second conductive portion 13 of the piezoelectric element 10 adjacent to the acoustic matching section 20 corresponding to that piezoelectric element 10. Furthermore, the first conductive layer 32R corresponding to the piezoelectric element 10 and the second conductive layer 31R disposed on this first conductive layer 32R constitute a multi-layer conductive member 30Rr disposed on the second conductive portion 13 of the piezoelectric element 10 adjacent to the acoustic matching section 20 corresponding to that piezoelectric element 10.

[0026] [Details of each component of the ultrasound probe] The backing material 50 supports the plurality of piezoelectric elements 10 and absorbs ultrasonic waves emitted from the piezoelectric elements 10 in the downward direction D. The backing material 50 is formed of a rubber material such as ferrite rubber.

[0027] The piezoelectric portion 11 of the piezoelectric element 10 is made of a piezoelectric material, such as piezoelectric ceramics such as PZT (lead zirconate titanate) or polymer materials such as PVDF (polyvinylidene fluoride).

[0028] The acoustic matching section 20 is intended to match the acoustic impedance between the piezoelectric body section 11 of the piezoelectric element 10 and the subject to facilitate the incidence of ultrasound waves into the subject. The acoustic matching section 20 can be formed from a material having an acoustic impedance smaller than that of the piezoelectric body section 11 and larger than that of the subject. The acoustic matching section 20 can also be formed by stacking multiple layers made of such materials. For example, by stacking an acoustic matching layer made of a material having an acoustic impedance lower than that of an acoustic matching layer arranged on the second conductive section 13 of the piezoelectric element 10, a layer structure is formed in which the acoustic impedance decreases stepwise from the piezoelectric body section 11 toward the subject.

[0029] The first conductive layer 32F, the first conductive layer 32R, the second conductive layer 31F, and the second conductive layer 31R are each preferably made of silver, although there are no particular restrictions on the material as long as they are conductive. The first conductive layer 32F, the first conductive layer 32R, the second conductive layer 31F, and the second conductive layer 31R are each preferably made of a conductive material having an acoustic impedance that is smaller than the acoustic impedance of the piezoelectric portion 11 and larger than the acoustic impedance of the subject.

[0030] The insulating filler 40 is made of an insulating resin material, etc. Examples of the resin material include silicone resin and epoxy resin.

[0031] Although not shown in FIG. 1, the ultrasonic probe 100 may have acoustic lenses fixed to the upper surfaces of the conductive member 30Fr, the conductive member 30Rr, the acoustic matching section 20, and the insulating filler 40.

[0032] [Ultrasonic probe operation] By applying a pulsed or continuous-wave voltage between the first conductive portions 12 of the plurality of piezoelectric elements 10 and the conductive members 30Rr and 30Fr connected to the second conductive portions 13 of the plurality of piezoelectric elements 10, the piezoelectric portions 11 expand and contract, generating pulsed or continuous-wave ultrasonic waves. When these ultrasonic waves are incident on the subject via the acoustic matching unit 20, they are combined to form an ultrasonic beam that propagates through the subject. When ultrasonic echoes propagating through the subject and reflected are incident on the respective piezoelectric portions 11 via the acoustic matching unit 20, the respective piezoelectric portions 11 deform, and a signal voltage is generated between the first conductive portion 12 and the second conductive portion 13 in response to this deformation. The signal voltage generated in the plurality of piezoelectric elements 10 is extracted from between the first conductive portion 12 of each piezoelectric element 10 and the conductive members 30Fr and 30Rr, and received as a received signal. An ultrasound image is generated based on this received signal.

[0033] [Preferred embodiments of the first conductive layer 32R and the first conductive layer 32F] As mentioned above, it is effective to reduce the array pitch P from the viewpoint of obtaining high-resolution ultrasonic images and suppressing the occurrence of grating noise. The gaps between the detection units are formed by cutting using a dicing saw, which will be explained in the manufacturing process below. Currently, the lower limit of the width of a dicing blade mounted on a dicing saw is approximately 15 μm. In other words, since the width D2 shown in FIGS. 3 and 4 cannot be made smaller than 15 μm, in order to reduce the array pitch P, it is necessary to reduce the width D1 of the detection units.

[0034] When the width D1 is reduced, for example, the adhesive area between the piezoelectric element 10 and the acoustic matching unit 20 and the adhesive area between the piezoelectric element 10 and the backing material 50 are reduced. Therefore, in order to alleviate thermal strain caused by differences in thermal expansion coefficients between the components constituting the detection unit, it is effective to prevent the ultrasonic probe 100 from being placed in a high-temperature environment during the manufacturing process. Furthermore, in order to ensure the performance of the ultrasonic probe 100, it is important to prevent the ultrasonic probe 100 from being exposed to a high-temperature environment during the manufacturing process. When the ultrasonic probe 100 is not placed in a high-temperature environment during the manufacturing process, the hardness of the first conductive layer 32R and the first conductive layer 32F of the detection unit may become smaller than the hardness of the acoustic matching unit 20 and the piezoelectric element 10.

[0035] Furthermore, in the detection unit, the first conductive layer 32R and the first conductive layer 32F may have a smaller volume than the acoustic matching section 20 and the piezoelectric element 10, respectively. Therefore, when the width D1 is reduced, the bonding area between the first conductive layer 32R and the first conductive layer 32F and other components is reduced.

[0036] In this way, if the width D1 is reduced, the bonding area between the first conductive layer 32R and the first conductive layer 32F and other components becomes smaller, or the hardness of the first conductive layer 32R and the first conductive layer 32F becomes smaller, during the dicing process to form the detection unit, the first conductive layer 32R and the first conductive layer 32F may fall in the left-right direction LR due to the force acting from the dicing blade and the water flow for cooling and removing cutting debris, and the acoustic matching section 20 and the piezoelectric element 10 may also be dragged and fall.

[0037] As a result of the verification, it was found that by setting the ratio (HF / D1) of the thickness (thickness HF shown in FIG. 3) which is the length in the up-down direction UD of the first conductive layer 32F to the width (width D1 shown in FIG. 3) which is the length in the left-right direction LR of the first conductive layer 32F to 1.6 or less (in other words, setting the thickness HF to 1.6 times the width D1 or less), it is possible to suppress tilt of the first conductive layer 32F in the left-right direction LR even if the width D1 is small or the hardness of the first conductive layer 32F is reduced. Specifically, it was found that by setting the ratio (HF / D1) to 1.6 or less, it is possible to suppress tilt of the first conductive layer 32F in the left-right direction LR even if the width D1 is set to a small value of 25 μm or more and less than 40 μm (equivalent to an ultrasonic probe 100 that can be driven at 20 MHz to 23 MHz). Furthermore, it was found that by setting the ratio (HF / D1) to 1.6 or less, even if the Shore D hardness (hardness measured using a D-type testing machine (durometer type D) specified in JIS (Japanese Industrial Standards) Z 2246) of the first conductive layer 32F is in the range of 80 or more and 85 or less, that is, even if the ultrasonic probe 100 is not placed in a high-temperature environment during the manufacturing process, it is possible to suppress the first conductive layer 32F from falling in the left-right direction LR.

[0038] Similarly, it was found that by setting the ratio (HR / D1) of the thickness (thickness HR shown in FIG. 3) which is the length in the up-down direction UD of the first conductive layer 32R to the width (width D1 shown in FIG. 3) which is the length in the left-right direction LR of the first conductive layer 32R to 1.6 or less (in other words, setting the thickness HR to 1.6 times the width D1 or less), it is possible to suppress tilt of the first conductive layer 32R in the left-right direction LR even if the width D1 is small or the hardness of the first conductive layer 32R is reduced. Specifically, it was found that by setting the ratio (HR / D1) to 1.6 or less, it is possible to suppress tilt of the first conductive layer 32R in the left-right direction LR even if the width D1 is set to a small value of 25 μm or more and less than 40 μm (equivalent to an ultrasonic probe 100 that can be driven at 20 MHz to 23 MHz). Furthermore, it was found that by setting the ratio (HR / D1) to 1.6 or less, even if the Shore D hardness of the first conductive layer 32R is in the range of 80 or more and 85 or less, i.e., even if the ultrasonic probe 100 is not placed in a high-temperature environment during the manufacturing process, it is possible to suppress the first conductive layer 32R from falling in the left-right direction LR.

[0039] Considering the materials and structures generally used for the acoustic matching part 20, the Shore D hardness of the acoustic matching part 20 is greater than 85.

[0040] From the viewpoints of conductive performance and ease of manufacture, each of the first conductive layers 32F and 32R is preferably made of a heat-treated hardened silver paste. A preferred example of a heat-treated hardened silver paste is "LOCTITE ABLESTIK 2902" silver paste manufactured by LOCTITE, but this is not limited to this. This silver paste has a Shore D hardness of 80 when fired at 65°C for two hours, which is the firing condition for obtaining sufficient conductivity.

[0041] [Ultrasonic probe manufacturing process] The ultrasonic probe 100 described above is manufactured by sequentially performing the following first to seventh steps. The manufacturing process for the ultrasonic probe 100 will be described below with reference to Figures 5 to 20. An overview of each step will be described below first, followed by examples of each step.

[0042] <First step> (overview) A sheet-like piezoelectric element 10S perpendicular to the up-down direction UD is formed, and the formed piezoelectric element 10S is bonded to the front FPC board 60Fr and the rear FPC board 60Rr using a conductive material. The bonded assembly of the front FPC board 60Fr, the rear FPC board 60Rr, and the piezoelectric element 10S is then fixed to the backing material 50 using adhesive Ad. FIG. 5 is a schematic plan view showing the state after the first step. FIG. 6 is a schematic cross-sectional view taken along the arrows A1-A1 in FIG. 5. FIG. 7 is a schematic cross-sectional view taken along the arrows A2-A2 and A3-A3 in FIG. 5. The piezoelectric element 10S is the basis for multiple piezoelectric elements 10, and as shown in FIGS. 6 and 7, is a laminated body formed by stacking a first conductive portion 12S, a piezoelectric body portion 11S, and a second conductive portion 13S. (Example) Fuji Ceramics' "C91H" piezoelectric material was used, and this piezoelectric material was polished to a thickness of 60 μm using a polishing sheet to form a piezoelectric body portion 11S of a piezoelectric element 10S. A first conductive portion 12S made of a titanium film and a gold film was formed by sputter deposition on one surface of this piezoelectric body portion 11S. A second conductive portion 13S made of a titanium film and a gold film was formed by sputter deposition on the other surface of this piezoelectric body portion 11S. The piezoelectric element 10S thus formed was trimmed to the desired size using a dicing saw, and then ultrasonically cleaned and plasma cleaned to complete the sheet-like piezoelectric element 10S. Furthermore, a silver paste "LOCTITE ABLESTIK 2902" manufactured by LOCTITE was applied using a dispenser to the electrode pattern forming region 61Fr of the front FPC board 60Fr and the electrode pattern forming region 61Rr of the rear FPC board 60Rr. The piezoelectric element 10S was placed on this silver paste with the first conductive portion 12S in contact with the silver paste, and the silver paste was hardened by heat treatment (at 65°C for 2 hours), thereby bonding the piezoelectric element 10S to the front FPC board 60Fr and the rear FPC board 60Rr.

[0043] <Second process> (overview) As shown in Fig. 8, a sheet-like acoustic matching section 20S perpendicular to the up-down direction UD is formed in the center in the front-rear direction FR on the top surface of the piezoelectric element 10S shown in Fig. 5. Fig. 9 is a schematic cross-sectional view taken along the arrows A1-A1 in Fig. 8. Fig. 10 is a schematic cross-sectional view taken along the arrows A4-A4 in Fig. 8. The example in Fig. 10 shows the acoustic matching section 20S as a laminate of a first layer 21, a second layer 22, and a third layer 23. (Example) The first layer 21 was formed to a thickness of 25 μm from a mixture of epoxy resin "Epotek-330" manufactured by Epoxy Technology and iron powder with a particle size of 5 μm. The second layer 22 was formed to a thickness of 30 μm from a mixture of epoxy resin "Epotek-330" manufactured by Epoxy Technology and alumina powder with a particle size of 5 μm. The third layer 23 was formed with an epoxy resin "Epotek-330" manufactured by Epoxy Technology Co., Ltd., and had a thickness of 20 μm. After the first step, DER (registered trademark) 332 was applied as an epoxy resin to the upper surface of the piezoelectric element 10S, a first layer 21 was placed on top of that, DER (registered trademark) 332 was applied to the first layer 21, a second layer 22 was placed on top of that, DER (registered trademark) 332 was applied to the second layer 22, and a third layer 23 was placed on top of that, and then pressure was applied from the third layer 23 side to form a three-layer acoustic matching section 20S and bond the acoustic matching section 20S to the piezoelectric element 10S.

[0044] <Third step> (overview) A conductive material is applied to a region adjacent to the front side of the acoustic matching section 20S on the top surface of the piezoelectric element 10S in the state shown in Fig. 8, and a conductive material is applied to a region adjacent to the rear side of the acoustic matching section 20S on the top surface of the piezoelectric element 10S shown in Fig. 8. These conductive materials are hardened by heat treatment to form a first conductive layer 32FS extending in the left-right direction LR and a first conductive layer 32RS extending in the left-right direction LR, as shown in Fig. 11. Fig. 12 is a schematic cross-sectional view taken along the A1-A1 arrows in Fig. 11. Fig. 13 is a schematic cross-sectional view taken along the A2-A2 arrows and the A3-A3 arrows in Fig. 11. In the third step, the first conductive layer 32RS is formed so that the thickness HR, which is the length in the up-down direction UD of the first conductive layer 32RS shown in Fig. 13, is 1.6 times or less the width D1 described above, which is determined by the design values ​​of the ultrasonic probe 100. In addition, the first conductive layer 32FS is formed so that the thickness HF, which is the length in the up-down direction UD of the first conductive layer 32FS shown in Fig. 13, is 1.6 times or less the width D1 described above, which is determined by the design values ​​of the ultrasonic probe 100. (Example) Using a dispenser, silver paste "LOCTITE ABLESTIK 2902" manufactured by LOCTITE was applied to the piezoelectric element 10S after the second process, adjacent to the front side of the acoustic matching portion 20S. Using a dispenser, silver paste "LOCTITE ABLESTIK 2902" manufactured by LOCTITE was applied to the piezoelectric element 10S after the second process, adjacent to the rear side of the acoustic matching portion 20S. Thereafter, the silver paste was hardened by heat treatment (at 65° C. for 2 hours) to form the first conductive layers 32FS and 32RS.

[0045] <Fourth process> (overview) The piezoelectric element 10S, on whose upper surface the acoustic matching section 20S, the first conductive layer 32FS, and the first conductive layer 32RS are formed in the third step, is then divided into multiple pieces in the left-right direction LR by cutting to form multiple piezoelectric elements 10. FIG. 14 is a schematic plan view showing the state after the fourth step is completed. As shown in FIG. 14, the piezoelectric element 10S on which the acoustic matching section 20S, the first conductive layer 32FS, and the first conductive layer 32RS are formed is cut by moving the dicing blade from the rearward direction Rr to the forward direction Fr. By repeatedly cutting while changing the position of the dicing blade in the left-right direction LR, multiple detection units with a width D1 are arranged in the left-right direction LR at an arrangement pitch P. The cut area 40a shown in FIG. 14 indicates the area cut by the dicing blade. Fig. 15 is a schematic cross-sectional view taken along the arrows A2-A2 and A3-A3 in Fig. 14. Fig. 16 is a schematic cross-sectional view taken along the arrows A4-A4 in Fig. 14. As shown in Figs. 15 and 16, the cutting region 40a reaches the backing material 50. This results in electrical isolation between the multiple line electrodes 71 and between the multiple line electrodes 72. (Example) The piezoelectric element 10S, on whose upper surface the acoustic matching portion 20S, the first conductive layer 32FS, and the first conductive layer 32RS were formed in the third step, was divided into a plurality of pieces in the left-right direction LR by cutting to form 256 piezoelectric elements 10. The dicing conditions were as follows: Dicing conditions: Pitch (arrangement pitch P in Figure 14): 40 μm Number of cuts: 280 Feed speed: 1.5 mm / sec Rotational speed: 30,000 rpm Dicing blade: 15μm width Z09-SD2500-Y1-60 51.0 x 0.015 (Disco) Dicing saw: DAD 323 (Disco) Since the first conductive layer 32FS and the first conductive layer 32RS have a low Shore D hardness, the load on the dicing blade during dicing can be reduced, thereby extending the life of the dicing blade. Furthermore, the soft first conductive layer 32FS and the first conductive layer 32RS can also serve as a countermeasure against chipping during dicing.

[0046] <Fifth process> (overview) The cut region 40a formed in the fourth step is filled with an insulating filler 40. Fig. 17 is a schematic plan view showing the state after the fifth step. Fig. 18 is a schematic cross-sectional view taken along the arrows A2-A2 and A3-A3 in Fig. 17. Fig. 19 is a schematic cross-sectional view taken along the arrows A4-A4 in Fig. 17. (Example) The cutting area 40a formed in the fourth step was filled with silicone resin "RTV630" manufactured by Momentive Inc. The filling was performed to eliminate air bubbles inside the cutting area 40a by evacuating the inside of the vacuum chamber using a rotary pump for about 10 minutes.

[0047] <Sixth step> (overview) The upper surfaces of the first conductive layers 32F and 32R in Fig. 17 are activated. The upper surfaces of the first conductive layers 32F arranged in the left-right direction LR and the insulating filler 40 between them are cut with a dicing blade, thereby activating the upper surfaces of the first conductive layers 32F. Similarly, the upper surfaces of the first conductive layers 32R arranged in the left-right direction LR and the insulating filler 40 between them are cut with a dicing blade, thereby activating the upper surfaces of the first conductive layers 32R. In the sixth step, the upper surfaces of the first conductive layers 32F and 32R are slightly removed to such an extent that the thicknesses of the first conductive layers 32F and 32R in the up-down direction UD (thicknesses HR and HF shown in FIG. 15) do not substantially change. In other words, even after the sixth step, the thicknesses of the first conductive layers 32F and 32R are substantially the same as they were after the third step (1.6 times the width D1 or less). Furthermore, this sixth step is not essential and may be omitted. (Example) After the fifth step, the upper surfaces of the first conductive layers 32F and 32R were cut and activated with the dicing saw used in the fourth step.

[0048] <Seventh process> (overview) 20, a second conductive layer 31F is formed on the upper surfaces of the activated first conductive layers 32F so as to straddle these layers. Also, a second conductive layer 31R is formed on the upper surfaces of the activated first conductive layers 32R so as to straddle these layers. (Example) Silver paste "LOCTITE ABLESTIK 2902" manufactured by LOCTITE was applied to the upper surfaces of the activated first conductive layers 32F using a dispenser. Silver paste "LOCTITE ABLESTIK 2902" manufactured by LOCTITE was applied to the upper surfaces of the activated first conductive layers 32R using a dispenser. Thereafter, the silver paste was hardened by heat treatment (at 65° C. for 2 hours) to form second conductive layers 31F and 31R. Thereafter, the upper surfaces of the second conductive layer 31F and the second conductive layer 31R were cut using the dicing saw used in the fourth step so that the upper surfaces of the second conductive layer 31F and the second conductive layer 31R were aligned with the upper surface of the acoustic matching section 20.

[0049] [First Modification] Fig. 21 is a diagram showing a first modified example of the ultrasonic probe 100, and is a schematic cross-sectional view corresponding to the cross section taken along the line AA in Fig. 1. The modified example shown in Fig. 21 is the same as Fig. 2 except that the first conductive layer 32R of the conductive member 30Rr having a multi-layer structure is omitted, and only the second conductive layer 31R is formed behind the acoustic matching unit 20. When manufacturing the ultrasonic probe of the modified example shown in Fig. 21, the first conductive layer 32RS is not formed in the third step (Fig. 11) described above, and the fourth step (Fig. 14) and the fifth step (Fig. 17) are performed, and then, in the seventh step, the second conductive layer 31R is formed behind the acoustic matching unit 20, spanning multiple piezoelectric elements 10.

[0050] [Second Modification] Fig. 22 is a diagram showing a second modified example of the ultrasonic probe 100, and is a schematic cross-sectional view corresponding to the cross section taken along the line AA in Fig. 1. The modified example shown in Fig. 22 is the same as Fig. 2 except that the multi-layered conductive member 30Rr has been removed and the acoustic matching unit 20 has been formed up to the region where the multi-layered conductive member 30Rr had been formed. When manufacturing the ultrasonic probe of the modified example shown in Fig. 22, in the second step (Fig. 8) described above, the acoustic matching unit 20S is formed up to the region where the first conductive layer 32RS had been formed, and then in the third step (Fig. 11), only the first conductive layer 32FS is formed, and then the fourth step (Fig. 14) and the fifth step (Fig. 17) are performed, and then in the seventh step, the second conductive layer 31F is formed on the front side of the acoustic matching unit 20.

[0051] [Verification results] 23 is a diagram showing the verification results of the ultrasonic probe manufactured according to the example of the manufacturing process described above. The details of Examples 1 to 4, Reference Examples 1 and 2, and Comparative Examples 1 and 2 shown in FIG. 23 will be described below.

[0052] Example 1 An ultrasonic probe compatible with 23 MHz driving was fabricated with the configuration shown in Figures 1 to 4. The total number of piezoelectric elements 10 was 256, and the width D1 of the piezoelectric elements 10 was 25 µm. The ratio (HR / D1) of the first conductive layer 32R formed in the third process was 0.4, and the ratio (HF / D1) of the first conductive layer 32F formed in the third process was 0.4.

[0053] Example 2 An ultrasonic probe was fabricated in the same manner as in Example 1, except that the ratio (HF / D1) of the first conductive layer 32F formed in the third step was changed to 1.4.

[0054] Example 3 An ultrasonic probe having the modified configuration shown in Fig. 22 was fabricated. The total number of piezoelectric elements 10 was 256, and the width D1 of the piezoelectric elements 10 was 25 µm. The ratio (HF / D1) of the first conductive layer 32F formed in the third step was 1.4.

[0055] Example 4 An ultrasonic probe was fabricated in the same manner as in Example 1, except that the ratio (HF / D1) of the first conductive layer 32F formed in the third step was changed to 1.6.

[0056] (Reference example 1) An ultrasonic probe was fabricated in the same manner as in Example 1, except that the width D1 of the piezoelectric element 10 was changed to 40 μm, the ratio (HR / D1) of the first conductive layer 32R formed in the third process was changed to 2.6, and the ratio (HF / D1) of the first conductive layer 32F formed in the third process was changed to 2.6.

[0057] (Reference example 2) An ultrasonic probe was fabricated in the same manner as in Example 1, except that the width D1 of the piezoelectric element 10 was changed to 63 μm, the ratio (HR / D1) of the first conductive layer 32R formed in the third process was changed to 2.3, and the ratio (HF / D1) of the first conductive layer 32F formed in the third process was changed to 2.3.

[0058] (Comparative Example 1) An ultrasonic probe was fabricated in the same manner as in Example 1, except that the ratio (HF / D1) of the first conductive layer 32F formed in the third step was changed to 1.8.

[0059] (Comparative Example 2) An ultrasonic probe was fabricated in the same manner as in Example 1, except that the ratio (HF / D1) of the first conductive layer 32F formed in the third step was changed to 1.7.

[0060] The "Tilt / Fall Rate" shown in Figure 23 indicates the percentage of detection units that have fallen or tilted left or right out of 256 detection units. The evaluation "OK" shown in Figure 23 indicates that the detection unit has not fallen or tilted at all and is a good product with no performance issues. The evaluation "NG" shown in Figure 23 indicates that the detection unit has fallen or tilted and cannot be used as a product.

[0061] As can be seen from comparing Examples 1 to 4 with Comparative Examples 1 and 2, when the ratio (HF / D1) exceeds 1.6, tipping or tilting occurs. Furthermore, as shown in the results of Example 1, when the ratio (HR / D1) and the ratio (HF / D1) are set to 0.4, tipping or tilting does not occur. This indicates that the cause of the tipping or tilting in Comparative Examples 1 and 2 is due to the value of the ratio (HF / D1). These verification results show that tipping or tilting can be prevented by setting the ratio (HF / D1) to 1.6 or less. Furthermore, since the first conductive layer 32F and the first conductive layer 32R are formed of the same material and in the same manufacturing process, tipping or tilting can also be prevented by setting the ratio (HR / D1) to 1.6 or less.

[0062] According to the results of Reference Examples 1 and 2, when the width D1 is large, tilting or falling does not occur even when the ratio (HF / D1) and the ratio (HR / D1) exceed 1.6. One reason for this is the large bonding area between each of the first conductive layer 32F and the first conductive layer 32R and other components. However, even when the width D1 is large, tilting or falling is less likely to occur if the ratio (HF / D1) and the ratio (HR / D1) are set to 1.6 or less. Therefore, regardless of the width D1, setting the ratio (HF / D1) and the ratio (HR / D1) to 1.6 or less is effective in preventing tilting or falling. As shown in FIG. 23, setting the ratio (HF / D1) and the ratio (HR / D1) to 1.6 or less can prevent tilting or falling even when the width D1 is less than 40 μm. As a result, it becomes possible to efficiently manufacture ultrasonic probes that can be driven at high frequencies.

[0063] This specification describes at least the following items. Note that the components in parentheses correspond to those in the above-described embodiment, but are not limited to these.

[0064] (1) An ultrasonic probe (ultrasonic probe 100) having a plurality of piezoelectric elements (piezoelectric elements 10) arranged in a first direction (left-right direction LR), a support member (backing material 50) for supporting the plurality of piezoelectric elements; an acoustic matching unit (acoustic matching unit 20) disposed on the plurality of piezoelectric elements; conductive members (conductive member 30Fr, conductive member 30Rr) disposed adjacent to the acoustic matching unit and on the plurality of piezoelectric elements, Each of the plurality of piezoelectric elements is formed by a laminate in which a first conductive portion (first conductive portion 12), a piezoelectric body portion (piezoelectric body portion 11), and a second conductive portion (second conductive portion 13) are sequentially laminated above the support member, the conductive member includes a conductive layer having a multi-layer structure arranged on at least one end side of the acoustic matching portion in a second direction (front-rear direction FR) that is a direction intersecting the first direction, the conductive layer of the multi-layer structure includes a plurality of first conductive layers (first conductive layer 32F, first conductive layer 32R) respectively joined to the second conductive portions of the piezoelectric elements, and second conductive layers (second conductive layer 31F, second conductive layer 31R) stacked on the plurality of first conductive layers and electrically connecting the plurality of first conductive layers, The ultrasonic probe has the first conductive layer having a ratio of thickness (HF, HR) to width (D1) which is the length in the first direction of 1.6 or less.

[0065] (2) The ultrasound probe according to (1), The ultrasonic probe, wherein the first conductive layer is formed from a heat-treated hardened silver paste having a Shore D hardness in the range of 80 to 85.

[0066] (3) The ultrasound probe according to (1) or (2), The ultrasonic probe, wherein the width of the first conductive layer is 25 μm or more and less than 40 μm.

[0067] (4) An ultrasonic probe according to any one of (1) to (3), An ultrasonic probe in which the width of each of the plurality of piezoelectric elements, which is the length in the first direction, is the same as the width of the first conductor layer.

[0068] (5) An ultrasound probe according to any one of (1) to (4), The conductive member is an ultrasonic probe disposed on both ends in the second direction.

[0069] (6) An ultrasound probe according to any one of (1) to (5), The ultrasonic probe has a Shore D hardness of the first conductive layer that is smaller than a Shore D hardness of the acoustic matching portion.

[0070] (7) An ultrasonic diagnostic device comprising the ultrasonic probe according to any one of (1) to (6).

[0071] (8) A method for manufacturing an ultrasonic probe (ultrasonic probe 100) having a plurality of piezoelectric elements (piezoelectric elements 10) arranged in a first direction (left-right direction LR), wherein the width of the piezoelectric elements, which is the length in the first direction, is a predetermined value (D1), The direction intersecting the first direction is defined as a second direction (front-rear direction FR), and the direction perpendicular to the first direction and the second direction is defined as a third direction (up-down direction UD), a step (first step, FIG. 5) of fixing a sheet-like laminate (piezoelectric element 10S) perpendicular to the third direction and including a first conductive portion (first conductive portion 12S), a piezoelectric portion (piezoelectric portion 11S), and a second conductive portion (second conductive portion 13S) laminated in that order to a support member (backing material 50); a step (second step, FIG. 8) of forming an acoustic matching portion (acoustic matching portion 20S) in a partial region in the second direction on an upper surface of the laminate, which is a surface opposite to the support member side; a step (third step, FIG. 11 ) of forming first conductive layers (first conductive layers 32FS, 32RS) having thicknesses (HF, HR) in the third direction that are 1.6 times or less of the predetermined value on at least one end side of the acoustic matching portion in the second direction on the upper surface of the laminate; a step (fourth step, FIG. 14 ) of dividing the laminate, on which the acoustic matching portion and the first conductive layer are formed, into a plurality of pieces in the first direction by cutting, to form the plurality of piezoelectric elements; and forming, on the plurality of divided first conductive layers (first conductive layer 32F, first conductive layer 32R), second conductive layers (second conductive layer 31F, second conductive layer 31R) that span the plurality of first conductive layers (seventh step, FIG. 20).

[0072] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0073] This application is based on a Japanese patent application (Patent Application No. 2021-063176) filed on April 1, 2021, the contents of which are incorporated by reference into this application. [Explanation of symbols]

[0074] 10S,10 Piezoelectric element 11S, 11 Piezoelectric body 12S, 12 First conductive part 13S, 13 Second conductive part 20S,20 Acoustic matching section 21 First layer 22 Second layer 23 Third layer 30Fr, 30Rr Conductive material 31F,31R 2nd conductor layer 32F,32FS,32RS,32R 1st conductor layer 40a cutting area 40 Insulating filler 50 Backing material 60Fr front FPC 60Rr Rear FPC 61Fr, 61Rr electrode pattern forming area 71,72 Line electrodes 100 Ultrasound Probe

Claims

1. An ultrasonic probe having a plurality of piezoelectric elements arranged in a first direction, a support member for supporting the plurality of piezoelectric elements; an acoustic matching unit disposed on the plurality of piezoelectric elements; a conductive member disposed adjacent to the acoustic matching portion and on the plurality of piezoelectric elements, each of the plurality of piezoelectric elements is formed by a laminate in which a first conductive portion, a piezoelectric portion, and a second conductive portion are sequentially laminated above the support member; the conductive member includes a conductive layer having a multi-layer structure that is arranged on at least one end side of the acoustic matching section in a second direction that intersects with the first direction, the conductive layer of the multi-layer structure includes a plurality of first conductive layers respectively joined to the second conductive portions of the piezoelectric elements, and a second conductive layer stacked on the plurality of first conductive layers and electrically connecting the plurality of first conductive layers, The first conductive layer has a ratio of thickness to width, which is the length in the first direction, of 1.6 or less.

2. 2. The ultrasonic probe according to claim 1, The ultrasonic probe, wherein the first conductive layer is formed from a heat-treated hardened silver paste having a Shore D hardness in the range of 80 to 85.

3. 3. The ultrasonic probe according to claim 1, An ultrasonic probe, wherein the width of the first conductive layer is equal to or greater than 25 μm and less than 40 μm.

4. 4. The ultrasonic probe according to claim 1, An ultrasonic probe in which the width of each of the plurality of piezoelectric elements, which is the length in the first direction, is the same as the width of the first conductor layer.

5. 5. The ultrasonic probe according to claim 1, The conductive member is an ultrasonic probe disposed on both ends in the second direction.

6. 6. The ultrasonic probe according to claim 1, The ultrasonic probe has a Shore D hardness of the first conductive layer that is smaller than a Shore D hardness of the acoustic matching portion.

7. An ultrasonic diagnostic apparatus comprising the ultrasonic probe according to claim 1 .

8. A method of manufacturing an ultrasonic probe having a plurality of piezoelectric elements arranged in a first direction, the piezoelectric elements having a width, which is a length in the first direction, of a predetermined value, comprising: a direction intersecting the first direction is defined as a second direction, and a direction perpendicular to the first direction and the second direction is defined as a third direction; a step of fixing a sheet-like laminate, which is perpendicular to the third direction and in which a first conductive portion, a piezoelectric portion, and a second conductive portion are laminated in this order, to a support member; forming an acoustic matching portion in a partial region in the second direction on an upper surface of the laminate, the upper surface being a surface opposite to the support member side; forming a first conductor layer on at least one end side of the acoustic matching section in the second direction on the upper surface of the laminate, the first conductor layer having a thickness in the third direction that is 1.6 times or less of the predetermined value; a step of dividing the laminate, on which the acoustic matching portion and the first conductive layer are formed, into a plurality of pieces in the first direction by cutting, to form the plurality of piezoelectric elements; and forming a second conductor layer on the first conductor layer divided into a plurality of parts, the second conductor layer spanning the plurality of first conductor layers.

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