Patent Publication Number: US-2021186461-A1

Title: Convex-type ultrasound probe

Description:
TECHNICAL FIELD 
     The present invention relates to a convex ultrasonic probe. Particularly, the invention relates to a convex ultrasonic probe that includes a backing including a plurality of leads that electrically connect a plurality of vibration elements that are arranged two-dimensionally and a plurality of electronic devices. 
     BACKGROUND ART 
     An ultrasonic diagnostic device is used in a medical field. The ultrasonic diagnostic device is a device that transmits and receives an ultrasonic wave to and from a test object, and forms an ultrasonic image based on a reception signal obtained thereby. The ultrasonic wave is transmitted and received by an ultrasonic probe connected to a device main body. 
     Various types of ultrasonic probes are known, including a convex ultrasonic probe. In the convex ultrasonic probe, a plurality of vibration elements are arranged in an arc shape in one direction (usually longitudinal direction) of two-dimensional arrangement directions of a vibration element array, and an surface of the vibration element array has a curved shape (U shape). By using the convex ultrasonic probe, it is possible to observe with a wide angle at a deep portion of an ultrasonic irradiation region while keeping a certain field of view in a shallow portion of the ultrasonic irradiation region. 
     An ultrasonic probe including the convex ultrasonic probe may have a configuration including a vibration element array that includes a plurality of vibration elements and transmits and receives an ultrasonic wave, a backing that is provided on a lower side (side opposite to a transmission and reception surface) of the vibration element array and prevents excessive vibration of the vibration element array, and an electronic device further provided on a lower side of the backing. Examples of the electronic device include an IC that exhibits a channel reduction function for reducing the number of wirings contained in a cable that connects an ultrasonic probe and a device main body. 
     In the related art, in an ultrasonic probe having the above-described configuration, a backing including a plurality of leads (conductive wires) that electrically connect a plurality of vibration elements and an electronic device is proposed (for example, PTL 1). As disclosed in PTL 1, in a two-dimensional ultrasonic probe in which a vibration element array is two-dimensionally arranged, the plurality of leads of the backing are also two-dimensionally arranged. Further, in the related art, also in a convex two-dimensional ultrasonic probe, a backing including a plurality of leads that electrically connect a plurality of vibration elements and an electronic device is used (for example, PTL 2 and PTL 3). 
     PRIOR ART LITERATURE 
     Patent Literature 
     PTL 1: JP-A-2015-228932 
     PTL 2: JP-T-2008-526343 
     PTL 3: JP-A-2002-28159 
     SUMMARY OF INVENTION 
     Technical Problem 
     In an ultrasonic probe including a plurality of vibration elements that are arranged two-dimensionally, a backing including a plurality of leads and an electronic device, a relay substrate may be further provided between the backing including the plurality of leads and the electronic device. For example, after the electronic device is mounted on the relay substrate, the relay substrate and the plurality of leads of the backing are electrically connected to each other. Accordingly, the plurality of leads of the backing and the electronic device are electrically connected to each other via the relay substrate. 
     Here, a connection position of each of the plurality of leads of the backing with respect to the relay substrate and a terminal position of each terminal of the electronic device with respect to the relay substrate do not correspond to each other, which may cause a problem that a wiring pattern of the relay substrate may be complicated. For example, considering a case where the plurality of leads of the backing are connected to an upper side surface of the relay substrate and the electronic device is mounted on a lower side surface of the relay substrate, when the connection position of each of the plurality of leads on the upper side surface of the relay substrate and the terminal position of each terminal of the electronic device on the lower side surface of the relay substrate do not correspond to each other, the wiring pattern of the relay substrate is long and complicated so as to correct a deviation between the connection position and the terminal position. Particularly, the problem is significant when a plurality of electronic devices are provided. 
     An object of the invention is to simplify a wiring pattern of a relay substrate in a convex ultrasonic probe that includes a plurality of vibration elements that are arranged two-dimensionally, a backing including a plurality of leads, a plurality of electronic devices, and a relay substrate provided between the backing and the plurality of electronic devices. 
     Solution to Problem 
     The invention provides a convex ultrasonic probe including a vibration element array that includes a plurality of vibration elements that are arranged two-dimensionally in a curved direction corresponding to a longitudinal direction and a short direction perpendicular to the longitudinal direction; a backing that is provided on a lower side of the vibration element array and includes a lead array including a plurality of leads electrically connected to the plurality of vibration elements, wherein an upper side surface of the backing is a curved surface defined by the curved direction and the short direction; a plurality of electronic devices that are provided on a lower side of the backing; and a relay substrate that is a substrate extending in the longitudinal direction and the short direction and electrically connects the lead array and the plurality of electronic devices, in which lower end portions of the plurality of leads are grouped into a plurality of dense groups according to an arrangement of the plurality of electronic devices at least in the longitudinal direction. 
     According to the above-described configuration, the lower end portions of the plurality of leads of the backing are grouped into the plurality of dense groups according to the arrangement of the electronic devices at least in the longitudinal direction. That is, the lower end portion of each lead is gathered at a position corresponding to each electronic device. In the related art, when a deviation between a contact position of each lead of the backing and the relay substrate and a position (terminal) of the electronic device is corrected by a wiring pattern of the relay substrate, at least a length of the wiring pattern of a relay substrate  26  in the longitudinal direction can be reduced by grouping. That is, the wiring pattern of the relay substrate  26  is simplified. As described above, in the above-described configuration, each lead of the backing at least supplementarily corrects the deviation between the contact position of each lead of the backing and the relay substrate, and the position of the electronic device. 
     Preferably, an inter-group gap exists between two adjacent dense groups in the longitudinal direction, an inter-device gap exists between two adjacent electronic devices in the longitudinal direction, and an arrangement of a plurality of inter-group gaps existing on an upper side of the relay substrate corresponds to an arrangement of a plurality of inter-device gaps on a lower side of the relay substrate. 
     Preferably, the lead array includes a plurality of lead rows arranged in the short direction, each of the lead rows includes a plurality of leads arranged in the longitudinal direction, and a pitch between the plurality of lead rows in the short direction is constant. 
     In the convex ultrasonic probe, a length in the short direction is usually considerably shorter than a length in the longitudinal direction. Therefore, since the wiring pattern of the relay substrate in the longitudinal direction is likely to be long, that is, is likely to be complicated, it can be said that a demand for simplification in the longitudinal direction is particularly strong. On the other hand, difficulty of manufacturing the backing may be increased by grouping the plurality of leads not only in the longitudinal direction but also in the short direction. Therefore, by grouping the plurality of leads in the longitudinal direction and making the pitch between the leads constant in the short direction (not grouping) , simplification of the relay substrate in the longitudinal direction is achieved, and the difficulty of manufacturing the backing can be kept low. For example, by making the pitch of each lead in the short direction constant, it is possible to adopt a method of laminating a lead sheet in which the plurality of leads arranged in the longitudinal direction are embedded in a sheet-shaped backing base portion at the time of manufacturing the backing, and according to the method, the backing can be easily formed. 
     Preferably, each of the lead rows includes a plurality of sections arranged in an upper-lower direction with different wiring patterns, and a plurality of dense groups are formed by the wiring pattern in any one of the plurality of sections. 
     Preferably, the plurality of sections includes an upper end section that is an upper end portion of a lead row and has a radial pattern corresponding to the vibration element array; an intermediate section that is an intermediate portion of the lead row in the upper-lower direction and has a main wiring pattern which is a parallel wiring pattern; a lower end section that is a lower end portion of the lead row and has a grouping pattern including the plurality of dense groups which is a parallel wiring pattern; an upper transition section that is a section between the upper end section and the intermediate section and has an upper transition pattern that connects the radial pattern and the main wiring pattern; and a lower transition section that is a section between the intermediate section and the lower end section and has a lower transition pattern that connects the main wiring pattern and the grouping pattern. 
     Preferably, the radial pattern includes a plurality of lead upper end portions perpendicular to the curved surface. Preferably, the grouping pattern includes a plurality of lead lower end portions perpendicular to a horizontal plane defined by the longitudinal direction and the short direction. 
     Preferably, the plurality of lead lower end portions are grouped into a plurality of dense groups according to the arrangement of the plurality of electronic devices also in the short direction. 
     Preferably, the vibration element array is formed on an intermediate portion excluding both end portions of an upper side surface of the backing, and an electrode sheet that is laminated on an upper side of the vibration element array and is electrically connected to the leads at both ends of the upper side surface of the backing is provided. According to the configuration, the electrode sheet laminated on the upper side of the vibration element array can be electrically connected to the relay substrate via the lead. Accordingly, for example, the electrode sheet can be suitably connected to a ground potential. 
     Advantageous Effect 
     According to the invention, in the convex ultrasonic probe that includes a plurality of vibration elements that are arranged two-dimensionally, a backing including a plurality of leads, a plurality of electronic devices, and a relay substrate provided between the backing and the plurality of electronic devices, the wiring pattern of the relay substrate can be simplified. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a partial cross-sectional perspective view of a vibrator unit according to an embodiment. 
         FIG. 2  is a front cross-sectional view of a backing, a relay substrate, and ICs. 
         FIG. 3  is a side cross-sectional view of the backing, the relay substrate, and the ICs. 
         FIG. 4  is a horizontal cross-sectional view of the backing. 
         FIG. 5  is an enlarged view of an end portion in an X-axis direction which is an upper end portion of the backing. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an ultrasonic probe according to an embodiment will be described. The ultrasonic probe according to the present embodiment is connected to an ultrasonic diagnostic device and transmits and receives an ultrasonic wave to and from a test object. The ultrasonic probe according to the present embodiment is a convex two-dimensional ultrasonic probe. 
       FIG. 1  is a partial cross-sectional perspective view of a vibrator unit  10  incorporated in the ultrasonic probe according to the present embodiment. 
     As shown in  FIG. 1 , the vibrator unit  10  is formed by laminating members. In  FIGS. 1 to 5 , a lamination direction of the members in the vibrator unit  10  is defined as a Z-axis direction and directions orthogonal to the Z-axis are an X-axis direction and a Y-axis direction. In  FIG. 1 , an ultrasonic wave is transmitted toward a Z-axis positive direction side. That is, the Z-axis positive direction side is a transmission and reception surface side of the ultrasonic wave (test object side). In this specification, the Z-axis positive direction side is referred to as an “upper side” and a Z axis lower direction side is referred to as a “lower side”. A plane defined by the X axis and the Y axis is referred to as a “horizontal plane”. As a matter of course, since a posture of the ultrasonic probe changes, the terms “upper side”, “lower side”, and “horizontal plane” in this specification indicate relative directions or planes. 
     A vibration element array  12   a  is configured by two-dimensionally arranging a plurality of vibration elements  12 . As described above, since the ultrasonic probe according to the present embodiment is a convex two-dimensional ultrasonic probe, the plurality of vibration elements  12  are two-dimensionally arranged in a curved direction (direction indicated by X′ in  FIG. 1 ) corresponding to the X-axis direction and the Y-axis direction. In the present embodiment, the vibration element array  12   a  according to the present embodiment has a rectangular shape in a plan view, that is, the X-axis direction is a longitudinal direction, and the Y-axis direction is a short direction. In the present embodiment, one hundred and tens of vibration elements  12  are arranged in the curved direction, and several tens of vibration elements  12  are arranged in the short direction. 
     Each vibration element  12  is formed of such as a ceramic such as PZT (zircon and lead titanate) or a single crystal such as PMT-PT (lead magnesium niobate and lead titanate solid solution). A signal electrode (hereinafter referred to as a “lower electrode”) is provided on a lower side surface of each vibration element  12 . A signal electrode (hereinafter, referred to as an “upper electrode”) is also provided on an upper side surface of each vibration element  12 . In the present embodiment, the upper electrode of each vibration element  12  is connected to a ground potential, and a drive signal is applied to the lower electrode of each vibration element  12 . Accordingly, each of the vibration elements  12  vibrates. When the drive signal is supplied to each vibration element  12 , each vibration element  12  vibrates and an ultrasonic beam is transmitted. Each vibration element  12  receives a reflected echo that is reflected from the test object, and outputs a reception signal based on the received reflected echo. 
     An acoustic matching layer  14   a  laminated on the upper side of the vibration element array  12   a  is provided to prevent reflection of an ultrasonic wave on a surface of the test object by matching acoustic impedances between the vibration elements  12  and the test object. The acoustic matching layer  14   a  includes a plurality of acoustic matching elements  14  corresponding to the vibration elements  12 . The acoustic matching layer  14   a  is formed of, for example, a resin, a carbon atom, and a carbon. The acoustic matching layer  14   a  also has a curved shape in accordance with the curved shape of the vibration element array  12   a.  Although only one acoustic matching layer  14   a  is shown in  FIG. 1 , the acoustic matching layer  14   a  may be configured with a plurality of layers. 
     An electrode sheet  16  is laminated on an upper side of the acoustic matching layer  14   a.  The electrode sheet  16  is formed of, for example, a metal film such as a copper foil. The electrode sheet  16  is connected to a ground potential by a method to be described later, and is in contact with an upper side surface of the acoustic matching layer  14   a  (each acoustic matching element  14 ). As described above, since the acoustic matching layer  14   a  is a conductor, the upper electrode of each vibration element  12  is connected to the ground potential by laminating the electrode sheet  16  on an upper side of the acoustic matching layer  14   a.    
     A protective layer  18  is laminated on the upper side of the electrode sheet  16 . The protective layer  18  protects layers below the acoustic matching layer  14   a.  The protective layer  18  is formed of, for example, silicone rubber. The protective layer  18  also has a curved shape in accordance with the vibration element array  12   a  and the acoustic matching layer  14   a  which have the curved shape. An upper side surface of the protective layer  18  is a surface to be in contact with the test object, that is, a transmission and reception surface. 
     A backing  20  is provided on a lower side of the vibration element array  12   a.  The backing  20  includes a backing base portion  22  that prevents unnecessary vibration of the vibration element array  12   a,  and a lead array  24   a  that is formed of a plurality of leads  24  that electrically connect the lower electrodes of the vibrating elements  12  and a relay substrate  26  to be described later. In accordance with the vibration element array  12   a  having a curved shape, an upper side surface of the backing  20  is a curved surface defined by the curved direction (direction indicated by an arrow X′) and the short direction (Y-axis direction). 
     The backing base portion  22  is formed by mixing a damping material filler with a resin, for example, epoxy, urethane, or acrylic. The damping material filler is formed of a ceramic or a metal, for example, tungsten. 
     The plurality of leads  24  are two-dimensionally arranged in the X-axis direction and the Y-axis direction in accordance with the two-dimensional arrangement of the vibration elements  12 . Each of the plurality of leads  24  is electrically connected to the vibration element  12  on an upper end portion thereof, and is electrically connected to the relay substrate on a lower end portion thereof. Each lead  24  may be formed of a metal such as copper or phosphor bronze, but from the viewpoint of further reducing crosstalk between the leads  24 , a material between the leads  24  is preferably formed of a material having a low dielectric constant, for example, a polymer material such as epoxy or polyimide. 
     The details of the backing  20 , particularly, a wiring pattern of the leads  24  will be described later. 
     In  FIG. 1 , an XZ cross-section and a YZ cross-section of a laminated body including the backing  20 , the vibration element array  12   a,  the acoustic matching layer  14   a,  the electrode sheet  16 , and the protective layer  18  are shown. In  FIG. 1 , hatching of the backing  20 , the vibration element array  12   a,  and the acoustic matching layer  14   a  is omitted (the same applies to the subsequent drawings). 
     The relay substrate  26  extending in the horizontal plane is provided on a lower side of the backing  20 . The relay substrate  26  is a multilayer build-up substrate, and is a hard substrate formed of, for example, glass epoxy having a low dielectric constant. Alternatively, the relay substrate  26  may be a rigid flexible substrate in which a flexible cable is sandwiched by a rigid substrate. 
     A plurality of conductor pads are provided on an upper side surface of the relay substrate  26 , and the conductor pads and the leads  24  are electrically connected to each other. Connectors  28  are provided on side end portions of the upper side surface of the relay substrate  26 . A flexible cable  30  is connected to the connectors  28 . The flexible cable  30  is connected to a wire in a cable connected to an ultrasonic diagnostic device via a connector (not shown). That is, the relay substrate  26  (that is, an IC  32  to be described later) is electrically connected to an ultrasonic diagnostic device main body by the flexible cable  30 . 
     A plurality of ICs  32  serving as a plurality of electronic devices are mounted on a lower side surface of the relay substrate  26 . Accordingly, the relay substrate  26  serves as a substrate that relays an electrical connection between the vibration elements  12  or the lead array  24   a  and the plurality of ICs  32 . The IC  32  functions as a transmission sub-beamformer and a reception sub-beamformer. As the transmission sub-beam former, the IC  32  transmits a drive signal to the plurality of vibration elements  12  based on a transmission signal from the ultrasonic diagnostic device main body. As the reception sub-beamformer, the IC  32  performs phasing addition processing on reception signals from the plurality of vibration elements  12 , generates a processed reception signal, and transmits the processed reception signal to the ultrasonic diagnostic device main body. As described above, the IC  32  exhibits a function (channel reduction function) for reducing the number of signal lines between the vibration element array  12   a  and the ultrasonic diagnostic device main body. 
     An outline of the vibrator unit  10  according to the present embodiment is as described above. Hereinafter, the backing  20 , the relay substrate  26 , and the IC  32  will be described in detail. 
       FIG. 2  shows a front cross-sectional view (XZ cross-sectional view) of the backing  20 , the relay substrate  26 , and the ICs  32 . As shown in  FIG. 1 , the plurality of leads  24  are arranged two-dimensionally, and in  FIG. 2 , one lead row  24   b  including a plurality of leads  24  arranged in the longitudinal direction (X-axis direction) is shown. By arranging the lead row  24   b  as shown in  FIG. 2  in the short direction (Y-axis direction) , the lead array  24   a  in which the plurality of leads  24  are two-dimensionally arranged is formed. 
     On an upper curved surface of the backing  20 , a plurality of bumps  40  electrically connected to the leads  24  are formed. The bump  40  is a protruding portion formed of a metal and protruding from a surface of the upper curved surface, and is provided to further ensure electrical contact between each lead  24  and the lower electrode of each vibration element  12 . Similarly, on a lower horizontal surface of the backing  20 , a plurality of bumps  42  electrically connected to the leads  24  are formed. The bump  42  is also a protruding portion formed of a metal and protruding from a surface of the lower horizontal surface, and is provided to further ensure electrical contact between each lead  24  and the conductor pad provided on the upper side surface of the relay substrate  26 . 
     In the present embodiment, the IC  32  is a surface mount type package, and the IC  32  has a plurality of ball-shaped terminals  44  on an upper side surface thereof. The plurality of ball-shaped terminals  44  are connected to the conductor pads provided on the lower side surface of the relay substrate  26  by a method such as soldering, so that the IC  32  is mounted on the relay substrate  26 . In the present embodiment, six ICs  32  are provided. That is, as shown in  FIG. 2 , an IC row including three ICs  32  arranged in the longitudinal direction is formed, and two such IC rows are aligned in the short direction. As a matter of course, the number of ICs  32  may be changed as appropriate according to the number of the vibration elements  12  or the characteristics of each IC  32 . 
     Due to a difference between a pitch between the vibration elements  12  in the longitudinal direction and a pitch between the ball-shaped terminals  44  of the IC  32 , or the like, when the leads  24  of the backing  20  are linearly extended in an upper-lower direction (Z-axis direction), the contact position of each lead  24  and the relay substrate  26  (it can also be said a lower end position of each lead  24  and a position of each bump  42 ) and a position of each ball-shaped terminal  44  do not correspond to each other, and a deviation between both positions needs to be corrected in the wiring pattern of the relay substrate  26 , and as a result, the wiring pattern of the relay substrate  26  is complicated. Therefore, in the present embodiment, a lower end position of each lead  24  in at least the longitudinal direction is set to a position corresponding to the position of each IC  32  (each ball-shaped terminal  44 ) by the wiring pattern of the lead array  24   a.  That is, in the present embodiment, each lead  24  of the backing  20  supplementarily corrects the deviation between the lower end position of each lead  24  and the position of each ball-shaped terminal  44 . Details will be described below. 
     In the present embodiment, in the backing  20 , the lower end portions of the plurality of leads  24  contained in the lead rows  24   b  are grouped into a plurality of dense groups  46  according to the arrangement of the ICs  32  in the longitudinal direction. In  FIG. 2 , the lower end portions of the plurality of leads  24  are grouped into three dense groups  46 , a dense group  46   a,  a dense group  46   b,  and a dense group  46   c.  Each dense group  46  corresponds to each IC  32 . That is, the dense group  46   a  corresponds to an IC  32   a,  the dense group  46   b  corresponds to an IC  32   b,  and the dense group  46   c  corresponds to an IC  32   c.    
     Grouping means that the lower end portions of the plurality of leads  24  belonging to the same dense group  46  are disposed close to each other, and are disposed to be isolated from the lower end portions of the leads  24  belonging to another dense group. By grouping the lower end portions of the plurality of leads  24 , inter-group gaps  48  are generated between the dense groups  46  at the lower end portions of the plurality of leads  24 . Specifically, as shown in  FIG. 2 , an inter-group gap  48   a  is generated between the dense group  46   a  and the dense group  46   b,  and an inter-group gap  48   b  is generated between the dense group  46   b  and the dense group  46   c.    
     Although the inter-group gaps  48  are necessarily arranged in the longitudinal direction, an arrangement of the inter-group gaps  48  corresponds to an arrangement of inter-device gaps  50  in the longitudinal direction. The inter-device gaps  50  similarly exist between the ICs  32  arranged in the longitudinal direction. Specifically, the inter-group gap  48   a  corresponds to an inter-device gap  50   a,  and the inter-group gap  48   b  corresponds to an inter-device gap  50   b.  The inter-group gap  48  may not necessarily be located directly above the corresponding inter-device gap  50 . 
     Grouping of the lower end portions of the plurality of leads  24  is realized by the wiring pattern of the leads  24 . Specifically, as shown in  FIG. 2 , the lead row  24   b  includes a plurality of sections (regions) arranged in the upper-lower direction. That is, the lead row  24   b  includes an upper end section  52  which is an upper end portion of the lead row  24   b,  an intermediate section  54  which is an intermediate portion of the lead row  24   b  in the upper-lower direction, a lower end section  56  which is a lower end portion of the lead row  24   b,  an upper transition section  58  that is provided between the upper end section  52  and the intermediate section  54  and a lower transition section  60  that is provided between the intermediate section  54  and the lower end section  56 . The lower end portions of the leads  24  are grouped into a plurality of dense groups  46  by the wiring pattern of any one of the plurality of sections of the lead row  24   b.    
     As described above, the upper side surface of the backing  20  is a curved surface, and an upper end of the backing  20  is curved in an arc shape in the XZ cross-section as shown in  FIG. 2 . The upper end section  52  has a radial pattern in which a plurality of lead portions (lead upper end portions) are arranged radially according to the curved surface of the backing  20 . Specifically, each lead portion contained in the upper end section  52  extends in a direction perpendicular to the curved surface of the backing  20 . Since the pitch between the vibration elements  12  in the curved direction is constant, the pitch between the lead upper end portions contained in the radial pattern in the upper end section  52  is also constant. 
     The intermediate section  54  has a parallel wiring pattern in which a plurality of lead portions are arranged in parallel in the upper-lower direction (Z-axis direction). The intermediate section  54  is a section having a longer wiring length than other sections, that is, the parallel wiring pattern contained in the intermediate section  54  is the main wiring pattern. In the intermediate section  54 , the pitch between the lead portions contained in the main wiring pattern is preferably constant. Accordingly, crosstalk generated between the lead portions can be reduced as an overall intermediate section  54 . 
     The lower end section  56  has a parallel wiring pattern in which the plurality of lead portions (lead lower end portions) are arranged perpendicular to the horizontal plane which is the lower side surface of the backing  20 , that is, parallel in the upper-lower direction (Z-axis direction). As shown in  FIG. 2 , the lower end section  56  includes the plurality of dense groups  46 . That is, the lower end section  56  has a grouping pattern including the plurality of dense groups  46  formed by the parallel wiring pattern. The pitch between the lead portions in the lower end section  56  and the pitch between the lead portions in the intermediate section  54  may be different from each other. 
     The upper transition section  58  has an upper transition pattern formed by the plurality of lead portions that respectively connect the lower end of each lead portion contained in the radial pattern of the upper end section  52  and the upper end of each lead portion contained in the main wiring pattern of the intermediate section  54 . 
     The lower transition section  60  has a lower transition pattern formed by the plurality of lead portions that respectively connect the lower end of each lead portion contained in the main wiring pattern of the intermediate section  54  and the upper end of each lead portion contained in the grouping pattern of the lower end section  56 . 
     In the present embodiment, in the intermediate section  54 , an interval between the lead portions contained in the main wiring pattern is constant, whereas in the lower end section  56 , the plurality of dense groups  46  are formed so as to correspond to the ICs  36 . That is, in the present embodiment, grouping of the lower end portions of the leads into the dense groups  46  is realized by the lower transition pattern in the lower transition section  60  that connects the intermediate section  54  and the lower end section  56 . 
     Although only one lead row  24   b  is shown in  FIG. 2 , similarly for others lead rows  24   b  arranged in the short direction, the lower end portions of the plurality of leads  24  are grouped so as to correspond to the respective ICs  32 . 
       FIG. 3  shows a side cross-sectional view (YZ cross-sectional view) of the backing  20 , the relay substrate  26 , and the ICs  32 . As shown in  FIG. 3 , in the present embodiment, the pitch between the leads  24  in the short direction is constant, that is, the leads  24  are not grouped corresponding to the ICs  32  in the short direction, but for the short direction, the lower end portions of the leads  24  may also be grouped corresponding to the arrangement of the ICs  32  in the short direction. In the present embodiment, the deviation between the lower end position of each lead  24  in the short direction and the position of each ball-shaped terminal  44  is corrected by the wiring pattern of the relay substrate  26 . 
       FIG. 4  shows a horizontal cross-sectional view of the intermediate section  54  of the backing  20 . As described above, in the lead array  24   a,  the lead rows  24   b  are arranged in the short direction, and in at least the intermediate section  54 , the positions in the longitudinal direction (X-axis direction) of the leads  24  contained in an adjacent lead rows  24   b  are different from each other. That is, the plurality of leads  24  in at least the intermediate section  54  are in a staggered arrangement. Accordingly, a distance between the adjacent leads  24  can be increased, and the crosstalk between the leads  24  can be reduced. 
       FIG. 5  shows an enlarged view of an end portion in the longitudinal direction which is an upper end portion of the backing  20 . The vibration element array  12   a  and the acoustic matching layer  14   a  are laminated on an upper side of an intermediate portion excluding both end portions in the longitudinal direction on the upper side surface of the backing  20 . That is, as shown in  FIG. 5 , the upper side surface of the backing  20  has, on an end portion thereof in the longitudinal direction, an exposed portion  72  on which the vibration element array  12   a  and the acoustic matching layer  14   a  are not laminated. Also in the exposed portion  72 , a bump  40   a  connected to the lead  24  is formed. The bump  40   a  and the lead  24  connected to the bump  40   a  are connected to the ground potential of the relay substrate  26 . 
     In the present embodiment, the electrode sheet  16  laminated on the upper side of the acoustic matching layer  14   a  wraps around side surfaces of the vibration element array  12   a  and the acoustic matching layer  14   a  at the end portion in the longitudinal direction, and is in contact with the bump  40   a  located on the exposed portion  72 . Accordingly, the electrode sheet  16  is connected to the ground potential. Although there is one bump  40   a  (lead  24 ) that is in electrical contact with the electrode sheet  16  in  FIG. 5 , a plurality of bumps  40   a  may exist in the exposed portion  72 , and the plurality of bumps  40   a  may be in contact with the electrode sheet  16 . As shown in  FIG. 5 , the protective layer  18  extends in the longitudinal direction so as to cover the end portion of the backing  20  in the longitudinal direction. An adhesive is injected into a gap between the electrode sheet  16  in contact with the exposed portion  72  and the protective layer  18 . 
     The outline of the configuration of the ultrasonic probe according to the present embodiment is as described above. In the present embodiment, the lower end portions of the plurality of leads  24  are grouped so as to correspond to the ICs  32 , so that the lower end position of each lead  24  (position of the bump  42 ) and the position of the ball-shaped terminal  44  of the IC  32  are close to each other. Accordingly, the length of the wiring pattern of the relay substrate  26  in the longitudinal direction can be shortened. That is, the wiring pattern of the relay substrate  26  is simplified. Ideally, if the pitch of each lead  24  (bump  42 ) in the dense group  46  and the pitch of each ball-shaped terminal  44  are the same, the wiring pattern does not need to be drawn in the longitudinal direction in the relay substrate  26 . 
     In general, in the convex two-dimensional ultrasonic probe, since the length in the short direction is considerably shorter than the length in the longitudinal direction, the wiring pattern of the relay substrate  26  is likely to be long, particularly in the longitudinal direction, that is, the wiring pattern of the relay substrate  26  is likely to be complicated. On the other hand, by grouping the leads  24 , a degree of difficulty in manufacturing the backing  20  is increased. Therefore, in the present embodiment, by grouping the leads  24  only in the longitudinal direction, the length of the wiring pattern of the relay substrate  26  in the longitudinal direction that is highly demanded for simplification particularly is shortened, and the grouping is not performed in the short direction, thereby preventing an increase in manufacturing difficulty of the backing  20 . Particularly, by setting the pitch of each lead in the short direction to be constant, a manufacturing method of a sheet laminated type can be adopted at the time of manufacturing the backing  20 . Specifically, the backing  20  can be formed by laminating the sheet-shaped backing base portion  22  in which the lead row  24   b  having the wiring pattern as shown in  FIG. 2  is embedded in the short direction. 
     Although the embodiment according to the invention has been described above, the invention is not limited to the above embodiment, and various changes may be made without departing from the spirit of the invention. 
     REFERENCE SIGN LIST 
       10  vibrator unit,  12  vibration element,  12   a  vibration element array,  14  acoustic matching element,  14   a  acoustic matching layer,  16  electrode sheet,  18  protective layer,  20  backing,  22  backing base portion,  24  lead,  24   a  lead array,  26  relay substrate,  28  connector,  30  flexible cable,  32  IC,  40 ,  42  bump,  44  ball-shaped terminal,  46 ,  46   a,    46   b,    46   c  dense group,  48 ,  48   a,    48   b  inter-group gap,  50 ,  50   a,    50   b  inter-device gap,  52  upper end section,  54  intermediate section,  56  lower end section,  58  upper transition section,  60  lower transition section,  72  exposed portion.