Abstract:
An ultrasonic probe is provided with a CMUT chip having a plurality of transducer elements that change electromechanical coupling coefficients or sensitivities in accordance with a bias voltage to transmit and receive ultrasonic waves, an electric conducting layer formed on the ultrasonic irradiation side of the CMUT chip, an acoustic lens arranged on the ultrasonic irradiation side of the CMUT chip, an insulating layer formed in the direction opposite to the ultrasonic irradiation side of the acoustic lens, a housing unit that stores the CMUT chip in which the electric conducting layer and the insulating layer are fixed with an adhesive and the acoustic lens, wherein the insulating layer is formed by the material that includes at least either silicon oxide or paraxylene to prevent a solvent of the adhesive from soaking into the adhered portion.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to an ultrasonic probe, method for manufacturing the ultrasonic probe and ultrasonic diagnostic apparatus. 
       DESCRIPTION OF RELATED ART 
       [0002]    An ultrasonic diagnostic apparatus is for imaging a diagnostic image based on the reflected echo signals outputted from an ultrasonic probe. The ultrasonic probe has a plurality of ultrasonic transducers disposed therein. Ultrasonic transducers convert driving signals into ultrasonic waves to transmit them to an object to be examined, and receive the reflected echo signals produced from the object and convert them into electrical signals. 
         [0003]    In recent years, ultrasonic probes using a CMUT (Capacitive Micromachined Ultrasonic Transducer) have been developed. The CMUT is an ultrafine capacity-type ultrasonic transducer manufactured by semiconductor microfabrication process. In CMUT, transmission/reception sensitivity of ultrasonic waves, i.e. electromechanical coupling coefficient varies according to a bias voltage. A bias voltage is applied being overlapped with the driving signal provided from an ultrasonic-wave transmitting/receiving unit (for example, refer to [Patent Document 1]). 
       Prior Art Document 
     Patent Document 
       [0004]    Patent Document 1: U.S. Pat. No. 5,894,452 
         [0005]    However, in the CMUT probe disclosed in [Patent Document 1], a DC voltage is applied to the lower electrode as a bias voltage with respect to a silicon substrate. Therefore, there is a need to dispose an insulating layer so as to prevent the part for applying to the object from contacting the upper electrode of the CMUT chip. The insulating layer is formed on an acoustic lens using a method such as vacuum deposition, sputtering or CVD (Chemical Vapor Deposition). On the other hand, an electric conductive layer is formed on the CMUT chip. Then the insulating layer and the electric conducting layer are attached by adhesive agent. Such configured CMUT probe has a problem that when it is immersed in antiseptic solution such as alcohol, the antiseptic solution turns to solvent of adherent agent. The solvent melts adherent agent, and the melted adherent agent penetrate into the CMUT chip. The penetrated adherent agent hardens a frame body and a film body of the CMUT chip, whereby leading to dysfunction in transmission/reception of ultrasonic waves in the inner space segmented by the hardened frame body and film body. Such dysfunction of a CMUT chip caused by penetration of adherent agent still remains unsolved. 
         [0006]    The objective of the present invention is to provide the ultrasonic probe, the method for manufacturing the ultrasonic probe and the ultrasonic diagnostic apparatus capable of preventing dysfunction of CMUT chips due to penetration of adherent agent. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The ultrasonic probe related to the present invention comprises: 
         [0008]    a CMUT chip having a plurality of transducers that change electromechanical coupling coefficients or sensitivities in accordance with a bias voltage, configured to transmit/receive ultrasonic waves; 
         [0009]    an electric conducting layer formed on the ultrasonic-wave irradiation side of the uMUT chip; 
         [0010]    an acoustic lens disposed on the ultrasonic-wave irradiation side of the CMUT chip; 
         [0011]    an insulating layer formed in the direction opposite from the ultrasonic-wave irradiation side of the acoustic lens; and 
         [0012]    a housing unit configured to store the CMUT chip in which the electric conducting layer and the insulating layer are adhered with adhesive agent and the acoustic lens, 
         [0013]    wherein the insulating layer includes at least one of silicon oxide or paraxylene, and is formed by material which prevents the solvent of adhesive agent from penetrating into an adhesive part. 
         [0014]    In this manner, it is possible to provide an ultrasonic probe capable of preventing dysfunction of a CMUT chip due to penetration of adhesive agent. 
         [0015]    The method of manufacturing the ultrasonic probe related to the present invention comprising: 
         [0016]    a CMUT chip having a plurality of transducers that change electromechanical coupling coefficients or sensitivities in accordance with a bias voltage, configured to transmit/receive ultrasonic waves; 
         [0017]    an acoustic lens provided on the ultrasonic-wave irradiation side of the CMUT chip; 
         [0018]    a backing layer provided on the back surface side of the CMUT chip, configured to absorb transmission of the ultrasonic waves; 
         [0019]    an electric wiring unit provided on the side surface of the backing layer from the peripheral border of the CMUT chip, in which the signal pattern connected with an electrode of the CMUT chip is arranged; and 
         [0020]    a housing unit configured to store the CMUT chip, the acoustic lens, the backing layer and the electric wiring unit, 
         [0021]    is characterized in having: 
         [0022]    a step that adheres the CMUT chip on the top surface of the backing layer; 
         [0023]    a step that adheres the electric wiring unit to the peripheral border of the top surface of the backing layer; 
         [0024]    a step that connects the electric wiring unit and the CMUT chip via a wire; 
         [0025]    a step that fills a sealant around the wire; 
         [0026]    a step that forms electric conducting layer capable of connecting to the ground, on the ultrasonic-wave irradiation side of the CMUT chip; and 
         [0027]    a step that adheres the acoustic lens on the ultrasonic-wave irradiation side of the CMUT chip. 
         [0028]    In this manner, it is possible to provide the method for manufacturing an ultrasonic probe capable of preventing dysfunction of a CMUT chip due to penetration of adhesive agent. 
         [0029]    The ultrasonic diagnostic apparatus related to the present invention comprises: 
         [0030]    an ultrasonic probe configured to transmit/receive ultrasonic waves to/from an object; 
         [0031]    an image processing unit configured to construct an ultrasonic image based on the ultrasonic reception signal outputted from the ultrasonic probe; and 
         [0032]    a display unit configured to display the ultrasonic image, 
         [0033]    wherein the ultrasonic probe is a first ultrasonic probe. 
         [0034]    The first ultrasonic probe comprises: 
         [0035]    a CMUT chip having a plurality of transducers that change electromechanical coupling coefficients and sensitivities in accordance with a bias voltage, configured to transmit/receive ultrasonic waves; 
         [0036]    an electric conducting layer formed on the ultrasonic-wave irradiation side of the CMUT chip; 
         [0037]    an acoustic lens disposed on the ultrasonic-wave irradiation side of the CMUT chip; 
         [0038]    an insulating layer formed in the direction opposite from the ultrasonic-wave irradiation side of the acoustic lens; and 
         [0039]    a housing unit configured to store the CMUT chip in which the electric conducting layer and the insulating layer are adhered with adhesive agent and the acoustic lens, 
         [0040]    wherein the insulating layer includes at least one of silicon oxide or paraxylene, and formed by the material capable of preventing penetration of solvent of the adhesive agent into the adhesive agent part. 
         [0041]    In this manner, it is possible to provide an ultrasonic diagnostic apparatus capable of preventing dysfunction of a CMUT chip due to penetration of adhesive agent. 
         [0042]    In accordance with the present invention, it is possible to provide an ultrasonic probe, the method for manufacturing the ultrasonic probe and ultrasonic diagnostic apparatus capable of preventing dysfunction of a CMUT chip due to penetration of adhesive agent. 
     
    
     
       BRIEF DESCRIPTION OF THE DIAGRAMS 
         [0043]      FIG. 1  is a configuration diagram of ultrasonic diagnostic apparatus  1 . 
           [0044]      FIG. 2  is a configuration diagram of ultrasonic probe  2 . 
           [0045]      FIG. 3  is a configuration diagram of transducer  21 . 
           [0046]      FIG. 4  is a configuration diagram of transducer element  28 . 
           [0047]      FIG. 5  shows ultrasonic probe  2   a  related to first embodiment  1 . 
           [0048]      FIG. 6  is a pattern diagram showing the connection between ultrasonic diagnostic apparatus  1  and ultrasonic probe  2 . 
           [0049]      FIG. 7  shows ultrasonic probe  2   a  related to second embodiment. 
           [0050]      FIG. 8  shows wiring of ultrasonic probe  2 . 
           [0051]      FIG. 9  shows ground connection of base plate  40  in CMUT chip  20 . 
           [0052]      FIG. 10  shows manufacturing process of ultrasonic probe  2  illustrated in  FIG. 5 . 
           [0053]      FIG. 11  shows ultrasonic probe  2   f  related to fifth embodiment. 
           [0054]      FIG. 12  is a detailed drawing of an electric cable illustrated in  FIG. 11 . 
           [0055]      FIG. 13  shows ground connection of base plate  40  viewed from the top-surface side of CMUT chip  20 . 
           [0056]      FIG. 14  shows ground connection of base plate  40  viewed from the under-surface side of CMUT chip  20 . 
           [0057]      FIG. 15  is a schematic cross-sectional view showing ultrasonic probe  2   c  related to a seventh embodiment. 
           [0058]      FIG. 16  is a top view of a CMUT wafer related to an eighth embodiment. 
           [0059]      FIG. 17  is a top view of CMUT chip related to the eighth embodiment. 
           [0060]      FIG. 18  shows the method for forming an electric conducting layer related to a ninth embodiment. 
           [0061]      FIG. 19  shows the method for forming an electric conducting layer related to a tenth embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0062]    Preferable embodiments of the ultrasonic probe and ultrasonic diagnostic apparatus related to the present invention will be described below referring to the attached diagrams. In the following description, the same function parts are represented by the same reference numerals, and the duplicative description thereof is omitted. 
       (1. Configuration of the Ultrasonic Diagnostic Apparatus) 
       [0063]    First, configuration of ultrasonic diagnostic apparatus  1  will be described referring to  FIG. 1 . 
         [0064]      FIG. 1  is a configuration diagram of ultrasonic diagnostic apparatus  1 . 
         [0065]    Ultrasonic diagnostic apparatus  1  is configured by ultrasonic probe  2 , transmission/reception separating unit  3 , transmitting unit  4 , bias unit  6 , receiving unit  8 , phasing and adding unit  10 , image processing unit  12 , display unit  14 , control unit  16  and operation unit  18 . 
         [0066]    Ultrasonic probe  2  transmits/receives ultrasonic waves to/from an object to be examined while being applied to the object. Ultrasonic waves are transmitted to the object from ultrasonic probe  2 , and the reflected echo signals from the object are received by ultrasonic probe  2 . 
         [0067]    Transmitting unit  4  and bias unit  6  are the devices that provide driving signals to ultrasonic probe  2 . 
         [0068]    Receiving unit  8  receives the reflected echo signals outputted from ultrasonic probe  2 . Receiving unit  8  further executes processes such as analogue digital conversion to the received reflected echo signals. 
         [0069]    Transmission/reception separating unit  3  switches and separates the transmission and reception of ultrasonic waves so as to send the driving signals from transmitting unit  4  to ultrasonic probe  2  upon transmission, and to send the receiving signals from ultrasonic probe  2  to receiving unit  8 . 
         [0070]    Phasing and adding unit  10  executes phasing and adding of the received reflected echo signals. 
         [0071]    Image processing unit  12  constructs a diagnostic image (for example, a tomographic image or blood flow image) based on the phased and added reflected echo signals. 
         [0072]    Display  18  displays the image processed diagnostic image. 
         [0073]    Control unit  16  controls the above-mentioned respective components. 
         [0074]    Operation unit  18  gives commands to control unit  16 . Operation unit  18  is an input device such as a trackball, keyboard or mouse. 
       (2. Ultrasonic Probe  2 ) 
       [0075]    Next, ultrasonic probe  2  will be described referring to  FIG. 2˜FIG .  4 . 
       (2-1. Configuration of Ultrasonic Probe  2 ) 
       [0076]      FIG. 2  is a configuration diagram of ultrasonic probe  2 .  FIG. 2  is a partially-notched perspective view of ultrasonic probe  2 . 
         [0077]    Ultrasonic probe  2  comprises CMUT chip  20 . CMUT chip  20  is a group of one-dimensional array type transducers in which a plurality of transducers  21 - 1 ,  21 - 2 , . . . are disposed in strips. In transducer  21 - 1 , transducer  21 - 2 , . . . , a plurality of transducer elements  28  are disposed. Other types of transducer group such as the 2-dimensional array type or convex type may also be used instead. 
         [0078]    Backing layer  22  is provided on the back-surface side of CMUT chip  20 . Acoustic lens  26  is provided on the ultrasonic-wave irradiation side of CMUT chip  20 . CMUT chip  20  and backing layer  22 , etc. are contained in ultrasonic probe cover  25 . 
         [0079]    CMUT chip  20  converts the driving signals from transmitting unit  4  and bias unit  6  into ultrasonic waves, and transmits the ultrasonic waves to the object. Receiving unit  8  converts the ultrasonic waves produced from the object into electronic signals, and receives them as reflected echo signals. 
         [0080]    Backing layer  22  absorbs the transmission of ultrasonic waves projected from CMUT chip  20  to the back-surface side for suppressing superfluous vibration. 
         [0081]    Acoustic lens  26  converges the ultrasonic beams transmitted from CMUT chip  20 . Curvature of acoustic lens  26  is specified based on one focal distance. 
         [0082]    A matching layer may also be provided between acoustic lens  26  and CMUT chip  20 . The matching layer interfaces CMUT chip  20  and acoustic impedance of the object whereby improving transmission efficiency of ultrasonic waves. 
       (2-2. Transducer  21 ) 
       [0083]      FIG. 3  is a configuration diagram of transducers  21 . 
         [0084]    Upper electrode  46  of transducer element  28  is connected for each transducer  21  sectioned in major-axis direction X. In other words, upper electrode  46 - 1 , upper electrode  46 - 2 , . . . are juxtaposed in major-axis direction X. 
         [0085]    Lower electrode  48  of transducer element  28  is connected for each transducer  21  sectioned in minor-axis direction Y. In other words, upper electrode  48 - 1 , upper electrode  48 - 2 , . . . are juxtaposed in minor-axis direction Y. 
       (2-3. Transducer Element  28 ) 
       [0086]      FIG. 4  is a configuration diagram of transducer element  28 .  FIG. 4  is a cross-sectional view of one transducer element  28 . 
         [0087]    Transducer element  28  is configured by base plate  40 , film body  44 , film body  45 , upper electrode  46 , frame body  47  and lower electrode  48 . Transducer element  28  is formed by semiconductor microfabrication process. Transducer element  28  is equivalent to one element of a CMUT. 
         [0088]    Base plate  40  is a semiconductor substrate such as silicon. 
         [0089]    Film body  44  and frame body  47  are formed by semiconductor compound such as silicon compound. Film body  44  is provided on the ultrasonic-wave irradiation side of frame body  47 . Upper electrode  46  is provided between film body  44  and frame body  47 . Lower electrode  48  is provided on film body  45  formed on base plate  40 . Inner space  50  sectioned by frame body  47  and film body  45  is vacuated or filled with a predetermined gas. 
         [0090]    Upper electrode  46  and lower electrode  48  are connected to transmitting unit  4  for providing AD high-frequency voltage as a driving signal and bias unit  6  for applying AD voltage as a bias voltage respectively. 
         [0091]    When an ultrasonic wave is transmitted, AD bias voltage (Va) is applied to transducer element  28  via upper electrode  46  and lower electrode  48 , and an electric field is generated by bias voltage (Va). Film body  44  is under tension due to the generated electric field and has a predetermined electromechanical coupling coefficient (Sa). When a driving signal is provided from transmitting unit  4  to upper electrode  46 , an ultrasonic wave is projected from film body  44  based on the electromechanical coupling coefficient (Sa). 
         [0092]    Also, when AD bias voltage (Vb) is applied to transducer element  28  via upper electrode  46  and lower electrode  48 , an electric field is generated by bias voltage (Vb). Film body  44  is under tension due to the generated electric field, and has predetermined electromechanical coupling coefficient (Sb). When a driving signal is provided from transmitting unit  4  to upper electrode  46 , an ultrasonic wave is projected based on electromechanical coupling coefficient (Sb). 
         [0093]    Here, when bias voltage is “Va&lt;Vb”, electromechanical coupling coefficient is “Sa&lt;Sb”. 
         [0094]    On the other hand, in the case of receiving an ultrasonic wave, film body  44  is excited by the reflected echo signal generated from the object, and capacity of inner space  50  changes. According to the variation of inner space  50 , an electric signal is detected via upper electrode  46 . 
         [0095]    Electromechanical coupling coefficient of transducer element  28  is determined by the tension of film body  44 . Therefore, by controlling the tension of film body  44  by changing the bias voltage to be applied to transducer element  28 , even when the driving signal of the same amplitude is inputted, acoustic pressure (for example, amplitude) of the ultrasonic wave projected from transducer element  28  can be changed. 
       (3. First Embodiment) 
       [0096]    Next, the first embodiment will be described referring to  FIG. 5  and  FIG. 6 . 
       (3-1. Configuration Member of Ultrasonic Probe  2 ) 
       [0097]      FIG. 5  shows ultrasonic probe  2  related to the first embodiment.  FIG. 5  is a cross-sectional view of plane A of ultrasonic probe  2  shown in  FIG. 2 . 
         [0098]    Electric conducting layer  76  is formed along the ultrasonic-wave irradiation side of CMUT chip  20  and the side surface of flexible substrate  72  and backing layer  22 , and insulating film  78  which is an insulating layer is formed on the inner surface of acoustic lens  26 . Electric conducting layer  76  and insulating layer  78  are formed by the method such as vacuum deposition, sputtering or CVD, and electric conducting layer  76  is formed by Cu or AI film having electrical conductivity. Insulating layer  78  is attached to electric conducting layer  76  by adhesive. Insulating layer  78  is formed by silicon oxide film or paraxilene film, etc. and is chemical resistant. Being chemical resistant here means that is to suppress penetration of, for example, adherent used for adhering acoustic lens  26  into CMUT chip  20 . Electric conducting layer  76  is connected to ground  120  which is on the side of a main body via terminal area  82  connected by soldering or conductive adhesive and ground  84 . 
         [0099]    In this manner, since electric conducting layer  76  is provided on the ultrasonic-wave irradiation side of CMUT chip  20  as the ground layer, electrical safety of ultrasonic probe  2  with respect to the object can be improved. Also, since insulating film  78  is formed as insulating layer between acoustic lens  26  and CMUT chip  20 , the space between acoustic lens  26  and CMUT chip  20  can be protected by double insulation by acoustic lens  26  and insulating layer  78 . Therefore, safety of ultrasonic probe  2  can be improved. By providing more than two layers of insulating layers rather than one layer of insulating layer  78 , electrical safety can be further improved. 
         [0100]    Since electric conducting layer  76  is formed on the ultrasonic-wave irradiation side of CMUT chip  20 , it is not necessary to form the electrical conducting layer on the inner side of acoustic lens  26 . Also, since electric conducting layer  76  is formed along the side surface of flexible substrate  72  and backing layer  22 , electric conducting layer  76  and ground wire  84  can be connected directly via terminal area  82  by having backing layer  22  as the base. 
         [0101]    CMUT chip  20  is adhered on the top surface of backing layer  22  via adhesive layer  70 . Flexible substrate  72  (Flexible Printed Circuits: FPC) is provided along the peripheral border of the top surface and the side surfaces in four-directions of backing layer  22 . Flexible substrate  72  is adhered on the peripheral border of the top surface of backing layer  22  via adhesive layer  71 . 
         [0102]    Adhesive layer  70  and adhesive layer  71  are made of, for example, epoxide resin. By arbitrarily adjusting the thickness of adhesive layer  70  and adhesive layer  71 , the height and directional position of CMUT chip  20  and flexible substrate  72  can be adjusted. 
         [0103]    Flexible substrate  72  and CMUT chip  20  are electrically connected via wire  86 . Wire  86  is connected using the wire-bonding method. As for wire  86 , an Au wire, etc. can be used. Around the wire  86 , material such as photo curing resin  88  is filled as a sealant. Heat-hardening resin also may be used as the sealant. As for the thermal-hardening resin, the material having the same thermal expansion coefficient as the base material of the semiconductor should be used. By using thermal-hardening resin, material strength by thermal expansion can be improved more than the case of using photo curing resin. In place of the wire-bonding method, the flip-chip bonding method which enables attachment between pads may be used. By using the flip chip bonding method, limit in mounting such as chip size can be modified, compared to the internal connection by the wire bonding method. 
         [0104]    Acoustic lens  26  is adhered to CMUT chip  20  via adhesive layer  90  between insulating layer  78  formed on the inner surface and electric conducting layer  76  formed on the ultrasonic-wave irradiation side of CMUT chip  20 . As for the material for acoustic lens  26 , for example, silicon rubber is used. As for the material for adhesive layer  90 , it is desirable to use a material similar to the adhesive layer used for acoustic lens  26  (for example, silicon resin). 
         [0105]    The ultrasonic-wave irradiation surface of acoustic lens  26  is convex in the ultrasonic-wave irradiating direction within the range of at least region  23 . In CMUT chip  20 , transducer element  28  is disposed within the range corresponding at least to region  23 . Ultrasonic waves are irradiated from the convex part of acoustic lens  26 . 
         [0106]    The back surface of acoustic lens  26  has a concave portion at the position corresponding to the peripheral border of CMUT chip  20 . In this concave portion, a terminal area (the part of photo curing resin  88 ) of CMUT chip  20  and flexible substrate  72  is fitted. 
         [0107]    Ultrasonic probe cover  25  is provided to the side surfaces in the four direction of ultrasonic probe  2 . Ultrasonic probe cover  25  is fixed on the side surfaces in the four directions of acoustic lens  26 . An examiner operates ultrasonic probe  2  by holding ultrasonic probe cover  25  with his/her hand. Sealant  27  is filled in the gap between ultrasonic probe cover  25  and acoustic lens  26 . 
         [0108]    It is desirable that the upper end of ultrasonic probe cover  25  is positioned in the part above CMUT chip  20 . In this manner, even in an unexpected contingency such as dropping of the probe should occurred, CMUT chip  20  can be protected by restraining direct impact shock. 
       (3-2. Connection of Ultrasonic Probe  2 ) 
       [0109]      FIG. 6  is a pattern diagram showing the connection between ultrasonic diagnostic apparatus  1  and ultrasonic probe  2 . Ultrasonic diagnostic apparatus  1  and ultrasonic probe  2  are connected via cable  82 . Cable  82  has a plurality of coaxial cables  96 . 
         [0110]    Upper electrode  46  of transducer  28  is connected to wiring  85 . Wiring  85  is connected to wiring  91  in ultrasonic diagnostic apparatus  1  via an inner conductor of coaxial cable  96 . Wiring  91  is connected to receiving amplifier  100  in receiving unit  8  and transmitting unit  4  via transmission/reception separating circuit  98 . 
         [0111]    Lower electrode  48  of transducer element  28  is connected to wiring  66 . Wiring  66  is connected to wiring  62  in ultrasonic diagnostic apparatus  1  via an inner conductor of coaxial cable  96 . Wiring  62  is connected to bias unit  6 . 
         [0112]    The number of coaxial cables  36  is to be the sum of upper electrodes  46  and lower electrodes  48  commonly disposed in a plurality of transducer elements  28 . 
         [0113]    Substrate  40  of transducer element  28  is connected to wiring  87 . Wiring  87  is connected to wiring  93  of ultrasonic diagnostic apparatus  1  via an outer conductor of coaxial cable  96 . Wiring  93  is connected to ground  108  via a chassis ground of the main body (not shown in the diagram). 
         [0114]    Condenser  112  is disposed between wiring  66  and wiring  87 . This condenser  112  is a capacitative element for bypassing the electrical current from lower electrode  48 . 
         [0115]    Resistor  110  is disposed between wiring  91  and wiring  93 . This resistor  110  is a resistance element for stabilizing the DC potential of upper electrode  46  as the ground electrode in the case that AC current flows from upper electrode  46  to lower electrode  48 . 
         [0116]    Bias unit  6  is disposed between wiring  62  and wiring  93 . This bias unit  6  is for generating electric potential difference between upper electrode  46  and lower electrode  48 . Also, transmitting unit  4  causes upper electrode  46  to apply an AD high-frequency voltage as a driving signal. Concretely, DC=ground (reference potential) and AC=Vpp in upper electrode  46 , and DC=Vdc and AC=0 in lower electrode  48 . 
         [0117]    Electric conducting layer  76  of transducer element  28  is connected to wiring  84 . Wiring  84  is formed to cover inner circuits (wiring  85 , wiring  66 , condenser  112 , etc.) of ultrasonic probe  2 , and is connected to wiring  99  in ultrasonic diagnostic apparatus  1  via outer circumference of cable  82 . Wiring  99  is formed to cover inner circuits (wiring  91 , wiring  62 , resistor  110 , etc.) of ultrasonic diagnostic apparatus  1 , and is connected to ground  120 . Therefore, DC=0 and AC=0 in electric conducting layer  76 , wiring  84 , outer circumference of cable  82  and wiring  99 . 
         [0118]    Electric conducting layer  76 , wiring  84 , outer circumference of cable  82 , wiring  99  and ground  120  form a protection circuit, prevent penetration of electromagnetic waves from outside into inner circuits of ultrasonic diagnostic apparatus  1  and ultrasonic probe  2 , and also prevent discharge of electricity generated inside of ultrasonic diagnostic apparatus  1  and ultrasonic probe  2  to the outside. 
       (3-3. Effect of the First Embodiment) 
       [0119]    In this manner, insulating layer  78  is provided on the ultrasonic-wave irradiation side of CMUT chip  20  in ultrasonic probe  2  of the first embodiment. Thus it is possible to prevent dysfunction of CMUT chip due to penetration of adhesive. 
         [0120]    Since electric conducting layer  76  is disposed on the ultrasonic-wave irradiation side of CMUT chip  20  and electric conducting layer is a ground potential, it is possible to prevent electrification even when acoustic lens  26  on the irradiation side is damaged, whereby improving electrical safety of the ultrasonic probe with respect to an object. 
         [0121]    Also, by electric conducting layer  76 , ground wiring  84  and the chassis ground of the main device, an enclosed space of the ground potential is formed. In other words, since the main components or main body circuits of ultrasonic probe  2  are contained in the enclosed space having the ground potential, negative influence due to extraneous electrical waves or the electromagnetic waves produced from ultrasonic probe  2  to the outer device can be prevented. 
         [0122]    Also, ultrasonic probe  2  in the first embodiment, electric conducting layer  76  is formed along the inner surface and the outer surface of acoustic lens  26 , and is connected to ground  120  via highly-reliable electric conducting member  80  and ground wiring  84 . 
         [0123]    By such configuration, electric conducting layer  76  formed along the inner and outer surfaces of acoustic lens  26 , not the in-mold formed sheet-like electric conducting layer to be pulled out, can be easily and surely connected to ground wire  84  via electric conducting member  80 , thereby improving its mounting reliability and workability. 
         [0124]    Also, by using highly-reliable electric conducting layer  80 , it is possible to prevent electric conducting member  80  from being damaged upon being fixed on flexible substrate  72 . 
         [0125]    Also, while electric conducting member  80  and ground wire  84  are illustrated only on the left side surface of flexible substrate  72  in  FIG. 5 , they can be disposed in any one or more side surfaces in four directions of flexible substrate  72 . 
       (4. Second Embodiment) 
       [0126]    Next, the second embodiment will be described referring to  FIG. 7 . 
         [0127]      FIG. 7  shows ultrasonic probe  2   a  related to the second embodiment.  FIG. 7  is equivalent to the cross-sectional view of plane A in  FIG. 2 . 
         [0128]    While electric conducting layer  76  is formed along the ultrasonic-wave irradiation side of CMUT chip  20  and the side surfaces of flexible substrate  72  and backing layer  22  and connected to ground wire  84  via adhesive portion  82  in the first embodiment, insulating film  78   a  is to be formed as an insulating layer between CMUT chip  20  and electric conducting layer  76  in the second embodiment. In the same manner as embodiment 1, insulating film  78  is formed as an insulating layer on the inner surface of acoustic lens  26 . 
         [0129]    In accordance with the second embodiment, dysfunction of CMUT chip due to penetration of adhesive can be prevented as in the first embodiment. Also, since electric conducting layer  76  is provided as the ground layer on the ultrasonic-wave irradiation side of CMUT chip  20 , electrical safety of ultrasonic probe  2   a  can be improved with respect to an object, and voltage endurance can be improved between electric conducting layer  76  and wiring  86  and also between electric conducting layer  76  and CMUT chip  20  by providing insulating film  78   a.    
       (5. Third Embodiment) 
       [0130]    Next, the third embodiment will be described referring to  FIG. 8  and  FIG. 9 . 
         [0131]      FIG. 8  is a pattern diagram showing the wiring of ultrasonic probe  2 . 
         [0132]      FIG. 9  shows the ground connection of base plate  40  in CMUT chip  20 , and is the cross-sectional view of the B-B line illustrated in  FIG. 8 . 
         [0133]    In the periphery border of the top surface of CMUT chip  20 , upper electrode  46  of CMUT chip  20  and signal pattern  38  of flexible substrate  72  are connected by wire  86 - 1 , and lower electrode  48  of CMUT chip  20  and signal pattern  41  of flexible substrate  72  are connected by wire  86 - 2 . Photo curing resin  88  is filed around wire  86  and the terminal area is sealed. 
         [0134]    In a corner portion of CMUT chip  20 , electric conducting resin  89  is filled between CMUT chip  20  and flexible substrate  72 . Electric conducting resin  89  is equivalent to the terminal area between base plate  40  of CMUT chip  20  and ground wire  94 . Ground wire  94  is disposed between flexible substrate  72  and backing layer  22  in the corner portion of CMUT chip  20 . 
         [0135]    Base plate  40  is provided at the bottom surface of CMUT chip  20 . Base plate  40  is electrically connected to electric conducting resin  89 . Base plate  40  is connected to ground  108  via electric conducting resin  89  and ground wire  94 . 
         [0136]    Ground wire  94  in  FIG. 9  is equivalent to wiring  87  in  FIG. 6 . Electric conducting resin  89  is provided to the terminal area between base plate  40  and wiring  87 . 
         [0137]    In this manner, in accordance with the third embodiment, it is possible to prevent dysfunction of CMUT chip due to penetration of adhesive. 
         [0138]    Also, while there is wire  86  for connecting signal pattern  38  and signal pattern  41  of flexible substrate  72  and CMUT chip  20  in the periphery border of CMUT chip except the corner portion, base plate  40  of CMUT chip  20  and ground wire  94  are connected via electric conducting resin  89  which is filled in the corner portion of CMUT chip  20 . In this manner, a signal pattern connecting portion and a base plate ground connecting portion can be provided in the separate places, which makes its manufacturing easier. 
         [0139]    Since base plate  40  itself is a semiconductor, there is a possibility that high voltage is generated by base plate  40  in abnormal situations. In the third embodiment, base plate can be maintained in the ground potential by ground-connecting base plate  40  even in abnormal situations, to maintain safety of ultrasonic probe  2 . 
       (6. Fourth Embodiment) 
       [0140]    Next, the fourth embodiment will be described referring to  FIG. 10 . The fourth embodiment relates to the manufacturing method of ultrasonic probe  2  shown in  FIG. 5 .  FIG. 10  shows the manufacturing process of ultrasonic probe  2  illustrated in  FIG. 5 . 
         [0141]    CMUT chip  20  is adhered on the top surface of backing layer  22  by adhesive layer  70  (step S 1 ). 
         [0142]    Flexible substrate  72  is adhered to the periphery border of the top surface of backing layer  22  by adhesive  71  (step S 2 ). 
         [0143]    Flexible substrate  72  and CMUT chip  20  are electrically connected via wire  86 . Wire  86  is connected using the wire bonding method or flip chip bonding method (step S 3 ). 
         [0144]    Photo curing resin  88  is filled around wire  86  as a sealant (step S 4 ). 
         [0145]    Electric conducting layer  76  is formed (step S 5 ). 
         [0146]    Acoustic lens  26  is formed (step S 6 ), and insulating layer  78  is formed on the inner surface of acoustic lens  26  (step S 7 ). 
         [0147]    Acoustic lens  26  is adhered to the ultrasonic-wave irradiation surface of CMUT chip  20  by adhesive layer  90 . Electric conducting layer  76  is connected to ground wire  84 . Ultrasonic probe cover  25  is attached onto an ultrasonic probe. Sealant  27  is filled in the gaps between acoustic lens  26  or flexible substrate  72  and ultrasonic probe cover  25  (step S 8 ). 
         [0148]    According to the process described above, ultrasonic probe  2  shown in  FIG. 5  is manufactured. 
         [0149]    Also, insulating layer  78   a  may be formed before forming electric conducting layer  76  in the process of step S 5 . In this case, ultrasonic probe  2   a  shown in  FIG. 7  is manufactured. 
         [0150]    As for the forming of a layer, there are methods such as in-mold forming an insulating sheet attached with an electric conducting layer at the same time with the forming of acoustic lens  26 , or forming an insulating layer or electric conducting layer by physical or chemical vapor deposition. The in-mold forming method can form a layer with low cost, but the limit in thickness in forming the layer is about 10 μm. On the other hand, the vapor deposition method can form the layer as thin as about 1 μm in thickness. 
       (7. Fifth Embodiment) 
       [0151]    Next, the fifth embodiment will be described referring to  FIG. 11  and  FIG. 12 . The fifth embodiment relates to the electrical connection between CMUT chip  20  and flexible substrate  72 . 
         [0152]      FIG. 11  shows ultrasonic probe  2   f  related to the fifth embodiment.  FIG. 11  is equivalent to the cross-sectional view of plane A in  FIG. 2 . 
         [0153]      FIG. 12  is a detailed diagram of the electric terminal area shown in  FIG. 11 . 
         [0154]    While flexible substrate  72  and CMUT chip  20  are electrically connected via wire  86  using wire bonding method in the first embodiment, they are electrically connected via through hole  161  or through hole  171  in the fifth embodiment. 
         [0155]    The signal pattern of flexible substrate  72  is electrically connected with the electrode of CMUT chip  20  in the periphery border portion of the back surface of CMUT chip  20 . In the electric terminal area, notch portion  168  is provided on the periphery border portion of the top surface of backing layer  22  according to the thickness of flexible substrate  72 , adhesive layer  71  and adhesive layer  70 . 
         [0156]    Through hole  161  is a conducting path between upper electrode  46  of CMUT chip  20  and pad terminal  163  provided on the back surface of CMUT chip  20 . Through hole  171  is a conducting path between lower electrode  48  of CMUT chip  20  and pad terminal  173  provided on the back surface of CMUT chip  20 . 
         [0157]    In through hole  161  and through hole  171 , metal is filled or a metal layer is formed on their inner wall. In the part of base plate  40  in CMUT chip  20 , insulating portion  162  and insulating portion  172  are provided around through hole  161  and through hole  171 . It is preferable to provide insulating portion  167  also on the back surface of base plate  40 . 
         [0158]    Pad terminal  165  and pad terminal  175  provided to flexible substrate  72  are electrically connected to pad terminal  163  and pad terminal  173  provided to the under surface of CMUT chip  20  respectively by electric conducting adhesive  164  and electric conducting adhesive  174  such as anisotropic conducting adhesive sheets. 
         [0159]    Signal pattern  38  of flexible substrate  72  is electrically connected to upper electrode  46  of CMUT chip  20  via pad terminal  165 , electric conducting adhesive  164 , pad terminal  163  and through hole  161 . Signal pattern  41  of flexible substrate  72  is electrically connected to lower electrode  48  of CMUT chip  20  via pad terminal  175 , electric conducting adhesive  174 , pad terminal  173  and through hole  171 . 
         [0160]    In this manner, in the fifth embodiment, flexible substrate  72  and CMUT chip  20  are electrically connected via through hole  161  and through hole  171 . By such configuration, flexible substrate  72  and CMUT chip  20  can be electrically connected only by positioning the pad terminals without wires for electrical connection. 
         [0161]    While electrical connection is executed via a through hole on the back surface of CMUT chip in  FIG. 12 , it may be executed via a through hole on the ultrasonic-wave irradiation side of CMUT chip  20 . 
         [0162]    Also, in the case of connecting the electrode of CMUT chip  20  and the signal wire of flexible substrate  72  using the wire bonding method illustrated in  FIG. 5 , since wire  86  having high potential and electric conducting layer  76  having ground potential come close to each other, there are cases that ground potential of electric conducting layer  76  cannot be maintained since short-circuit is caused between electric conducting layer  76  and wire  86  due to defect of sealant such as photo curing resin  88  or pinhole defect of insulating layer  78 . On the other hand, in the case that the electrode of CMUT chip  20  and the signal wire of flexible substrate  72  are connected by the through hole shown in  FIG. 11  and  FIG. 12 , since the connecting wire and electric conducting layer  76  are not close to each other, short-circuit can be prevented and the ground potential of electric conducting layer  76  can be maintained, which leads to improvement in safety. 
         [0163]    Also, since wire  86  used in the wire bonding method shown in  FIG. 5  is a thin metal wire, it is subject to damage by acting force thus difficult to handle. On the other hand, in connection by the through holes shown in  FIG. 11  and  FIG. 12 , the process for connecting wires in the wire bonding method is not necessary, which makes it easier to handle. 
         [0164]    Also, in the connection using the wire bonding method shown in  FIG. 5 , etc., a sealant such as photo curing resin  88  is necessary for filling around wire  86 . The resin used as a sealant and wire  86  have different linear expansion coefficients. Generally, the linear expansion coefficient of the resin to be used for a sealant is greater than the one of metal. Thus alteration of temperature caused by expansion of the resin used for a sealant could lead to damage of wire  86 . Also, in the case that impure substance is included in the resin used for a sealant, electrical migration could lead to short-circuit between wire  86  and electric conducting layer  76 . On the other hand, in the connection using through holes shown in  FIG. 11  and  FIG. 12 , problems due to impure substances included in the resin will not be posed since wires or sealant are not necessary. 
         [0165]    In this manner, in the fifth embodiment, by executing connection using through holes in place of the connection by the wire bonding method, safety of ultrasonic probe  2  can be improved. 
       (8. Sixth Embodiment) 
       [0166]    Next, the sixth embodiment will be described referring to  FIG. 13  and  FIG. 14 . The sixth embodiment relates to the ground connection of substrate  40  in CMUT chip  20 . 
         [0167]    While substrate  40  is ground-connected via electric conducting resin  89  from the side surface of CMUT chip  20  in the third embodiment, substrate  40  is to be ground-connected from the top surface side (ultrasonic-wave irradiation side) or the lower surface side (back surface side) of CMUT chip  20  in the sixth embodiment. 
         [0000]    (8-1. Ground Connection from Top Surface Side of CMUT Chip) 
         [0168]      FIG. 13  shows the ground connection of substrate  40  from the top surface side of CMUT chip  20 . 
         [0169]    Through hole  181  is a conducting path between substrate  40  of CMUT chip  20  and pad terminal  182  provided on the top surface of CMUT chip  20 . Through hole  185  is a conducting path between ground wire  94  provided on the inner surface of flexible substrate  72  and pad terminal  184  provided on the top surface. Through hole  181  and through hole  185  are filled with metal, or a metal layer is formed on the inner walls thereof. 
         [0170]    Pad terminal  182  and pad terminal  184  are electrically connected via wire  183  using the wire bonding method. Substrate  40  of CMUT chip  20  is connected to ground  108  via through hole  181 , pad terminal  182 , wire  183 , pad terminal  184 , through hole  185  and ground wire  94 . 
         [0000]    (8-2. Ground Connection from Bottom Surface Side of a CMUT Chip) 
         [0171]      FIG. 14  shows the ground connection of substrate  40  from the bottom surface side of CMUT chip  20 . 
         [0172]    Through hole  191  is a conducting path between substrate  40  of CMUT chip  20  and pad terminal  192  provided to the bottom surface of CMUT chip  20 . Through hole  195  is a conducting path between ground wire  94  provided on the inner surface of flexible substrate  72  and pad terminal  194  provided on the top surface. Through hole  191  and through hole  195  are filled with metal, or a metal layer is formed on the inner walls thereof. 
         [0173]    Pad terminal  192  and pad terminal  194  are electrically connected by electric conducting adhesive  193  such as an anisotropic conducting adhesive sheet  193 . Substrate  40  of CMUT chip  20  is ground connected via through hole  191 , pad terminal  192 , electric conducting adhesive  193 , pad terminal  194 , through hole  195  and ground wire  94 . 
       (8-3 Effect of Sixth Embodiment) 
       [0174]    In this manner, in the sixth embodiment, substrate  40  of CMUT chip  20  can be ground-connected from the top surface or the bottom surface of CMUT chip  20  via through holes. By such configuration, ground connection of substrate  40  in CMUT chip  20  can be executed only by implementing the connection using the wire bonding method or positioning of the pad terminals, as substitute for filling electric conducting resin for ground-connection. By setting substrate  40  as the ground potential, the electric potential of CMUT chip can be stabilized which leads to stabilization of ultrasonic characteristics. 
         [0175]    In addition, there are upper electrode  46  and lower electrode  48  to which more than 100V of high voltage is applied, on substrate  40  of CMUT chip  20 . Since substrate  40  itself is a semiconductor, there is a possibility that substrate  40  will have a high voltage in abnormal circumstances. In the sixth embodiment, it is possible to maintain substrate  40  in the ground potential even in abnormal circumstances by ground-connecting substrate  40  via through holes, which leads to improvement in safety of ultrasonic probe  2 . 
       (9. Seventh Embodiment) 
       [0176]    Next, the seventh embodiment will be described referring to  FIG. 15 . 
         [0177]    Electric conducting layer  201  is formed in CMUT chip  20 , and it is formed in the process of manufacturing the CMUT wafer before segmentizing it into a number of CMUT chips. Since the CMUT wafer is manufactured using the semiconductor processing, this electric conducting layer  201  is formed in the wafer condition. While Al, Al—Cu alloy or Cu is used for the electric conducting layer in the above-mentioned semiconducting process, electrically conductive substance such as Ti, Cr, Au, Pt, TiN, TiW, or Si3N4 can be applied. 
         [0178]    As for the layer manufacturing method, there are methods such as vacuum deposition, sputtering and CVD. Also, while it is possible to form the above-mentioned electric conducting layer  201  after completing the manufacturing process of the CMUT wafer, it is preferable to form electric conducting layer  201  in the wafer condition before segmentizing the CMUT wafer using a method such as dicing, so as to avoid remnant of extraneous substances. In this case, electric conducting layer  201  can be formed using the method to spin-coat or spray-coat the electrically conductive coating material. 
         [0179]    Electric conducting layer  203  is formed on flexible substrate  204 , and is formed upon manufacturing flexible substrate  204 . In this regard, however, it is possible to form electric conducting layer  203  by sticking metal coat or Cu tape after forming flexible substrate  204 . Electric conducting layer  201  of CMUT chip  20  and electric conducting layer  203  of flexible substrate  204  are electrically connected by electric conducting layer  202 . Electric conducting layer  202  is formed using an electrically conductive tape such as a Cu tape or Al tape, or electrically conductive paste, etc. impregnated with Ag-particles or C-particles. 
         [0180]    Since electric conducting layer  201  is formed in the manufacturing process of a CMUT wafer as mentioned above, there is no engulfment of extraneous substances into an electric conducting layer while mounting CMUT chip  20  or flexible substrate  204 , or during the wire bonding process or the mounting process such as filling process of photo curing resin, thus there is no influence due to application of pressure in the acoustic lens bonding process, which leads to improvement in forming a safe ultrasonic probe. 
       (10. Eighth Embodiment) 
       [0181]    Next, the outline of the relationship between the CMUT wafer and the CMUT chip using  FIG. 16  and  FIG. 17 .  FIG. 16  shows the layout of a plurality of CMUT chips  30  in a plane of CMUT wafer  301 . The CMUT wafer  301  is manufactured using a wafer of, for example, 8 inches, 6 inches or 12 inches. After completing the manufacture of CMUT wafer  301 , it is diced along scribe lines  310 , and the respective CMUT chips  302  are segmented. 
         [0182]      FIG. 17  is a schematic diagram in which one CMUT chip  302  is enlarged. In CMUT chip  302 , electrode pad  303  is formed for electrically connecting to the outside. 
       (Ninth Embodiment) 
       [0183]    Next, the forming method of an electric conducting layer to CMUT wafer  301  will be described referring to  FIG. 18 .  FIG. 18  shows a D-D cross-section illustrated in  FIG. 17 . Electric conducting layer  202  is formed by CVD or sputtering on CMUT wafer  301  in which vibratory elements (not shown in the diagram) are completed (a). 
         [0184]    Next, photoresist  304  is formed by a spin coater or a spray (b). Next, photoresist aperture  305  is formed in photo resist  304  (c) by the photo lithography method. 
         [0185]    Then electric conducting layer aperture  306  of an electrode pad is formed on electric conducting layer  202  by dry etching or wet etching (d). Finally, by removing and cleansing photoresist  304 , forming of electric conducting layer  202  and electric conducting layer aperture  306  of electrode pad  303  for securing a conducting path to the outside by the wire bonding are completed. 
       (12. Tenth Embodiment) 
       [0186]    Next, other methods for manufacturing an electric conducting layer to CMUT wafer  301  will be described using FIG.  19 .  FIG. 19  shows a cross-sectional view of D-D plane shown in  FIG. 17 . The layer is formed by spin-coating or spray-coating photoresist  304  on CMUT wafer  301  in which a vibration elements (not shown in the diagram) are completed (a). 
         [0187]    Next, photoresist aperture  307  is formed on photoresist  304  using the photo lithography method (b). Then electric conducting layer  308  is formed by CVD or sputtering (c). 
         [0188]    Finally, by removing and cleansing photoresist  304 , electric conducting layer  308  on electrode pad  303  is removed, and electric conducting layer aperture  309  is formed (d). Compared to the method illustrated in  FIG. 18 , the advantage of this method is that there is no process for etching an electric conducting layer which makes it easier to form electric conducting layer aperture  309 . 
         [0189]    However, after removing the last photoresist  304 , burrs, etc. tend to remain on electric conducting layer  308  which remains on CMUT wafer  301 . This happens when the thickness of electric conducting layer  308  is thicker than the one of photoresist  304 , and also when electric conducting layer  308  is thicker than photoresist  304  while electric conducting layer  308  is connected by the edge portion of photoresist  304 . In order to prevent burrs from remaining, it is significant that the thickness of photoresist  304  is sufficiently thicker than the one of electric conducting layer  308 . 
         [0190]    It is known that the ultrasonic probes having configuration that an electric conducting layer is directly formed on a CMUT chip which is described in the first to the tenth embodiments have better acoustic characteristics compared to the conventional ultrasonic probes having the configuration that an electric conducting layer is formed on the side of an acoustic lens. In the case that an electric conducting layer is formed on the side of an acoustic lens, due to an adhesive layer for adhering the acoustic lens existing between the CMUT chip and the electric conducting layer and the distance between the sound source of ultrasonic waves and the electric conducting layer, there are cases that the ultrasonic waves reflected by the electric conducting layer return to the CMUT chip and are further reflected by the CMUT chip, whereby inducing multiple reflections. 
         [0191]    In accordance with the present invention, due to the configuration that an electric conducting layer is directly formed on a CMUT chip which makes the electric conducting layer itself to be the sound source to vibrate with transducer elements of ultrasonic waves, it is possible to provide an ultrasonic probe having excellent acoustic characteristic without generating the above-described multiple reflections. 
       (13. Other Matters) 
       [0192]    The above-described embodiments may be appropriately combined to configure an ultrasonic probe and ultrasonic diagnostic apparatus. 
         [0193]    Also, in the above-described embodiments, it is preferable to set the thickness of an electric conducting layer as about 0.1 μm, and the thickness of an insulating layer as about 1 μm. By making the thickness of the insulating layer and the electric conducting layer thin, the influence on the ultrasonic waves transmitted and received by the CMUT chip (influence to or attenuation of pulses and frequency property) can be restrained. 
         [0194]    The preferable embodiments of the ultrasonic probe and ultrasonic diagnostic apparatus according to the present invention have been described. However, the present invention is not limited to these embodiments. It is obvious that persons skilled in the art can make various kinds of alterations or modifications within the scope of the technical idea disclosed in this application, and it is understandable that they belong to the technical scope of the present invention. 
       DESCRIPTION OF REFERENCE NUMERALS 
       [0195]      1 : ultrasonic diagnostic apparatus,  2 : ultrasonic probe,  3 : transmission/reception separating unit,  4 : transmitting unit,  6 : bias unit,  8 : receiving unit,  10 : phasing and adding unit,  12 : image processing unit,  14 : display unit,  16 : controller,  18 : operation unit,  20 : CMUT chip,  21 - 1 ,  21 - 2 , . . . : transducer,  22 : backing layer,  25 : ultrasonic probe cover,  26 : acoustic lens,  27 : sealant,  28 : transducer element,  38  &amp;  41 : signal pattern,  40 : substrate,  46 : upper electrode,  48 : lower electrode,  72 : flexible substrate,  70 ,  71  &amp;  90 : adhesive layer,  76 : electric conducting layer (ground layer),  78  &amp;  78   a : insulating film (insulating layer),  84  &amp;  94 : ground wire (cable shielding wire),  86  &amp;  183 : wires,  88 : photo curing resin,  108  &amp;  120 : ground,  161 ,  171 ,  181 ,  185 ,  191  &amp;  195 : through hole,  163 ,  165 ,  173 ,  175 ,  182 ,  184 ,  192  &amp;  194 : pad terminal,  164 ,  174  &amp;  193 : electric conducting adhesive (anisotropic conducting adhesive sheet),  201 ,  202 ,  203  &amp;  308 : electric conducting layer,  204 : flexible substrate,  301 : CMUT wafer,  302 : CMUT chip,  303 : electrode pad,  304 : photoresist,  305  &amp;  307 : photoresist aperture,  306  &amp;  309 : electric conducting layer aperture.