JP2010154382A - Piezoelectric vibrator for ultrasonic probe, ultrasonic probe, ultrasonic diagnosis apparatus, and method of manufacturing piezoelectric vibrator for ultrasonic probe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator for an ultrasonic probe in which the dimension of the ultrasonic probe in thickness direction can be reduced by making a ground electrode shorter than the prior arts and a surface of a signal electrode can be smoothed as much as possible. <P>SOLUTION: A second filling part 34 provided in a piezoelectric body 26 of the piezoelectric vibrator 15 is formed with a filling material that is not ground but is to be protruded, rather than a piezoelectric material part 32, on a surface of the piezoelectric body 26 when the surface of the piezoelectric body 26 is ground, and has a protrusion 34a protruded from the surface of the piezoelectric body 26. On the other hand, a first filling part 33 is formed with a filling material of which grindability in grinding the surface of the piezoelectric body 26 is superior to that of the filling material forming the second filling part 34, and a protruding part 35 is formed on a surface of a ground electrode 29 by protruding a conductive layer 27 on the projection 34a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piezoelectric vibrator of an ultrasonic probe that transmits / receives ultrasonic waves to / from a subject, an ultrasonic probe, an ultrasonic diagnostic apparatus, and a method of manufacturing a piezoelectric vibrator in an ultrasonic probe.

  In an ultrasonic diagnostic apparatus that irradiates a subject with ultrasonic waves and images reflected echoes (echo) thereof, an ultrasonic probe that transmits and receives ultrasonic waves is connected to the main body of the ultrasonic diagnostic apparatus. The ultrasonic probe includes a piezoelectric vibrator made of a piezoelectric material such as PZT (lead zirconate titanate), an acoustic matching layer disposed on the ultrasonic irradiation side with respect to the piezoelectric vibrator, and the piezoelectric vibrator. In contrast, a backing material layer disposed on the opposite side of the ultrasonic irradiation side, and a flexible substrate sandwiched between the backing material and the piezoelectric vibrator and connected to the electrodes of the piezoelectric vibrator. Yes.

  As the piezoelectric vibrator, a piezoelectric vibrator having a so-called wraparound electrode structure in which a ground electrode is formed on the same surface as the signal electrode on the surface opposite to the surface on which the signal electrode is formed. (For example, refer to Patent Document 1). In the piezoelectric vibrator, on the surface on which the signal electrode is formed, ground electrodes are formed at both ends so as to sandwich the signal electrode. When a voltage is applied to the piezoelectric vibrator, the signal electrode The intermediate portion having the elastic vibrations. The piezoelectric vibrator having the wraparound electrode structure has an advantage that the connection structure can be simplified because the ground electrode, the signal electrode, and the flexible substrate can be connected on the same surface. Yes.

  Further, as the piezoelectric vibrator, a composite piezoelectric body in which a gap formed in a piezoelectric body made of PZT or the like is filled with a resin as a filler is known (for example, see Patent Document 2). This composite piezoelectric body has an effect that the acoustic impedance becomes smaller than PZT and approaches the acoustic impedance of the acoustic matching layer, and the electromechanical coupling coefficient can be increased. In the case where the piezoelectric vibrator having the wraparound electrode structure as described above is a composite piezoelectric body, an intermediate portion where the signal electrode is formed is filled with resin.

  Furthermore, a reflective layer formed of tungsten or the like may be adhered to the surface of the piezoelectric vibrator opposite to the ultrasonic wave irradiation side. The reflection layer reflects ultrasonic waves generated by elastic vibration of the piezoelectric vibrator toward the direction of the subject (on the acoustic matching layer side). When the resonance vibration by the piezoelectric vibrator is excited, the reflection layer A standing wave with a fixed end is formed.

Incidentally, the reflection layer is bonded to the signal electrode and the ground electrode when the piezoelectric vibrator has a wraparound electrode structure. Here, the tungsten forming the reflective layer has conductivity, and the flexible substrate is connected to the reflective layer, and is electrically connected to the electrodes via the reflective layer.
JP 2007-167445 A Japanese Patent Laid-Open No. 2002-232929

  By the way, in the ultrasonic probe, when the piezoelectric vibrators arranged in the ultrasonic scanning direction become long, the thickness of the ultrasonic probe increases. When the ultrasonic probe becomes thick, particularly in the sector type ultrasonic probe, when scanning from the intercostal space, the contact with the body surface of the subject becomes insufficient, which is not preferable for imaging. Therefore, it is not preferable that the piezoelectric vibrator becomes long. However, in the piezoelectric vibrator having the wraparound electrode structure, the piezoelectric vibrator becomes longer by the amount of the ground electrode in addition to the signal electrode on one surface. Here, in the piezoelectric vibrator having a wraparound electrode structure, both end portions where the ground electrode is formed are portions that do not vibrate when transmitting and receiving ultrasonic waves, and are portions that do not directly contribute to transmission and reception of ultrasonic waves. is there. Therefore, conventionally, the length of the piezoelectric vibrator is suppressed by making the ground electrode as short as possible.

  The signal electrode and the ground electrode of the piezoelectric vibrator are connected to the conductor such as the flexible substrate or the reflective layer by pressure bonding using an epoxy resin adhesive or the like. In such a connection structure, the raised portions of the surface of each electrode of the piezoelectric vibrator and the surface of the conductor of the flexible substrate or the surface of the reflective layer come into contact with each other so that conduction is established. Yes. For this reason, in the related art, the length of the ground electrode formed on the same surface as the signal electrode is such that a minimum area can be ensured for electrical connection with the flexible substrate. Yes. Therefore, the length of the ground electrode cannot be shortened any more, and if the length of the piezoelectric vibrator is to be shortened, the length of the signal electrode must be shortened and the sensitivity is deteriorated. It will be.

  In addition, when the reflective layer is bonded to the piezoelectric vibrator, if there are irregularities on the bonding surfaces of the piezoelectric vibrator and the reflective layer that face each other, an adhesive accumulates in the concave portion, resulting in a thick adhesive layer. Here, when the adhesive layer becomes thick, the reflective layer cannot function sufficiently as a fixed end in the resonance vibration excited by the piezoelectric vibrator. As a result, the power of the ultrasonic wave radiated to the subject side is impaired. Further, even during reception of ultrasonic waves, if the reflective layer does not function sufficiently as a fixed end, an echo signal is transmitted to the reflective layer side, and the echo signal received by the piezoelectric vibrator is reduced. Therefore, in order to make the adhesive layer between the piezoelectric vibrator and the reflective layer as thin and uniform as possible, the opposing adhesive surfaces of the piezoelectric vibrator and the reflective layer are both mirror-finished by grinding to form irregularities. Can be suppressed to less than micron order.

  However, when the piezoelectric vibrator is formed of a composite piezoelectric body, the resin and the piezoelectric material, which are fillers, have different elastic moduli. Therefore, when the piezoelectric vibrator is mirror-finished, the resin portion is compressed during grinding. As a result, stress concentrates on the portion of the piezoelectric material. Accordingly, the piezoelectric material portion is ground rather than the resin portion, and after the grinding, the stress is released and the resin portion expands and protrudes. As a result, the unevenness of the surface of the signal electrode, which is an adhesive surface with the reflective layer in the piezoelectric vibrator, becomes larger than a micron order, and the adhesive layer between the reflective layer has a thin and uniform thickness. I can't. Accordingly, it is desired to make the surface of the signal electrode as smooth as possible, particularly in a piezoelectric vibrator formed of a composite piezoelectric material.

  The present invention has been made in view of such circumstances, and the problem to be solved is that the length of the ground electrode is made shorter than before and the dimension in the thickness direction of the ultrasonic probe is made smaller. It is also possible to provide a piezoelectric vibrator of an ultrasonic probe, an ultrasonic probe, an ultrasonic diagnostic apparatus, and a method of manufacturing the piezoelectric vibrator in the ultrasonic probe that can make the surface of a signal electrode as smooth as possible.

  The present invention has been made in order to solve the above-mentioned problems. In the invention of the first aspect, the signal electrode constituted by the conductive layer provided on the surface of the piezoelectric body and the ground electrode are identical in the piezoelectric body. A piezoelectric vibrator of an ultrasonic probe formed on the surface of the piezoelectric probe, wherein the piezoelectric body comprises a filling portion formed by filling a gap formed in the piezoelectric body with a filler and a piezoelectric material. A first filling portion provided in a portion of the piezoelectric vibrator having the signal electrode as the filling portion, and the grounding formed on the same plane as the signal electrode in the piezoelectric vibrator. A second filling portion provided in a portion having an electrode, and the second filling portion is not ground more than the piezoelectric material portion when the surface of the piezoelectric body is ground. Depending on the filler material that will protrude The first filling portion has a grindability when the surface of the piezoelectric body is ground, and the second filling portion has a protrusion protruding from the surface of the piezoelectric body. The conductive layer is formed on a surface of the ground electrode by projecting the conductive layer on the protrusion in the second filling portion. This is a piezoelectric vibrator of an ultrasonic probe.

  The invention of the second aspect is characterized in that, in the invention of the first aspect, the filler of the first filling portion and the filler of the second filling portion are resins having different grindability from each other. It is a piezoelectric vibrator of an ultrasonic probe.

  According to a third aspect of the invention, in the first or second aspect of the invention, a conductor for applying a voltage to the piezoelectric vibrator is surface-bonded to the signal electrode and the ground electrode. It is a piezoelectric vibrator of an ultrasonic probe.

  The invention according to a fourth aspect is the invention according to any one of the first to third aspects, wherein the ground electrode is formed on the same surface as the signal electrode at both ends of the piezoelectric body and has the protrusion. One portion, a second portion formed on a surface opposite to the surface on which the first portion is formed in the piezoelectric body, and the first portion and the second portion of the piezoelectric body. And the signal electrode is sandwiched between the first part of the ground electrode on the surface of the intermediate part between both ends of the piezoelectric body. The first filling portion is provided at an intermediate portion between both end portions of the piezoelectric body, while the second filling portion is provided at both end portions of the piezoelectric body. The piezoelectric transducer of the ultrasonic probe.

  The invention according to a fifth aspect is the invention according to any one of the first to fourth aspects, wherein each of the first filling portion and the second filling portion has a plurality, and an interval between the adjacent second filling portions is set. The piezoelectric vibrator of the ultrasonic probe is narrower than an interval between the adjacent first filling portions.

  The invention according to a sixth aspect is the invention according to any one of the first to fifth aspects, wherein a surface of the piezoelectric vibrator on which the signal electrode and the ground electrode are formed is formed on the surface generated by the piezoelectric vibrator. A piezoelectric vibrator of an ultrasonic probe, characterized in that a reflective layer that reflects sound waves is adhered.

  A seventh aspect of the invention is an ultrasonic probe comprising the piezoelectric vibrator according to any one of the first to sixth aspects of the invention.

  An eighth aspect of the invention is the ultrasonic irradiation according to the seventh aspect of the invention, wherein the piezoelectric vibrator is opposite to a surface of the piezoelectric vibrator on which the signal electrode and the ground electrode are formed. An acoustic matching layer disposed on the side, a backing material layer disposed on a surface side on which the signal electrode and the ground electrode are formed with respect to the piezoelectric vibrator, the backing material layer, and the piezoelectric vibrator; An ultrasonic probe comprising: a flexible substrate disposed between and connected to the signal electrode and the ground electrode.

  According to a ninth aspect of the present invention, in the eighth aspect of the invention, the piezoelectric vibrator is bonded to a surface on which the signal electrode and the ground electrode are formed, and is generated by elastic vibration of the piezoelectric vibrator. An ultrasonic probe comprising a conductive reflective layer that reflects sound waves, wherein the flexible substrate is connected to the signal electrode and the ground electrode through the reflective layer.

  A tenth aspect of the invention is an ultrasonic diagnostic apparatus including the ultrasonic probe according to any one of the seventh to ninth aspects.

  According to an eleventh aspect of the present invention, there is provided a first groove forming step of forming a first groove having a predetermined depth in a piezoelectric body made of a piezoelectric material, and filling the first groove with a filler to provide a first filling portion. A first filling portion forming step to be formed; a second groove forming step of forming a second groove having a predetermined depth in a portion different from the portion in which the first groove is formed in the piezoelectric body; A second filling portion forming step of filling the second groove with a filler to form a second filling portion, and grinding for grinding the surface of the piezoelectric body on which the first filling portion and the second filling portion are formed A conductive layer forming step of forming a conductive layer to be a signal electrode and a ground electrode on the surface of the piezoelectric body that has undergone the grinding step, and in the second filling portion forming step, the second groove When the surface of the piezoelectric body is ground in the grinding step, the filler filled in is ground more than the piezoelectric material portion. The filler that fills the first groove in the first filling portion forming step is the surface of the piezoelectric body in the grinding step. The material to be ground is superior to the filler forming the second filling portion, and in the grinding step, a part of the second filling portion protrudes from the surface of the piezoelectric body. The first filling portion is ground so as not to protrude from the surface of the piezoelectric body, and in the conductive layer forming step, the conductive layer is protruded above the protrusion. A method for manufacturing a piezoelectric vibrator in an ultrasonic probe, characterized in that a protrusion is formed on the surface of the piezoelectric body, and the portion of the conductive layer where the protrusion is formed is a ground electrode. It is.

  According to the present invention, the surface of the piezoelectric body is ground after the gap is formed in the piezoelectric body and the filler is filled, and before the conductive layer is provided on the surface of the piezoelectric body. The protrusion of the second filling portion can be formed. Then, by providing the conductive layer on the surface of the piezoelectric body on which the protrusion of the second filling portion is formed in this way, the conductive layer on the protrusion protrudes and the protrusion on the surface of the ground electrode The part can be formed. Since this protrusion can ensure conduction between the ground electrode and a conductor to be crimped in order to apply a voltage to the piezoelectric vibrator, the length of the ground electrode can be made shorter than before. it can. Therefore, the piezoelectric vibrator can be made shorter than before without degrading the sensitivity, and thereby the thickness dimension of the ultrasonic probe can be reduced.

  The piezoelectric body is a composite piezoelectric body in which a first filling portion is formed in a portion having the signal electrode. The first filling portion has a grindability when the surface of the piezoelectric body is ground. The first filler is formed by grinding the surface of the piezoelectric body before providing the conductive layer because the filler is made of a material superior to the filler forming the second filler. It can be formed so as not to protrude from the surface of the piezoelectric body. Accordingly, since the surface of the signal electrode constituted by the conductive layer formed on the surface of the piezoelectric body can be made as smooth as possible, an adhesive layer between the signal electrode and the conductor to be pressure-bonded by an adhesive can be formed as much as possible. Thin and uniform.

  Further, the smoothness of the surface of the signal electrode is high, while the protrusion is formed on the surface of the ground electrode, so that the average thickness of the piezoelectric vibrator is smaller than the portion having the signal electrode. Also, the portion having the ground electrode is thicker. Thereby, the stress when the conductor is crimped to the signal electrode and the ground electrode formed on the same surface of the piezoelectric vibrator can be concentrated on the ground electrode, and the ground electrode, the conductor, Can be firmly bonded. Therefore, it can be said that the length of the ground electrode can be made shorter than before.

  The first filling portion and the second filling portion each have a plurality, and the interval between the adjacent second filling portions is made smaller than the interval between the adjacent first filling portions. The space | interval of the projection part formed on the protrusion part of a 2 filling part becomes narrower. As a result, the average thickness in the portion having the ground electrode in the piezoelectric vibrator becomes thicker, so that the signal electrode and the ground electrode and the conductor for applying a voltage to the piezoelectric vibrator are surface-bonded. In this state, the stress applied to the crimping surface is concentrated on the ground electrode. Accordingly, the pressure-bonding force between the ground electrode and the conductor can be enhanced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
A first embodiment will be described. FIG. 1 is a block diagram showing a schematic configuration of an example of an embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 2 is a partially cutaway perspective view showing the appearance of an ultrasonic probe in the ultrasonic diagnostic apparatus shown in FIG. 3 is a perspective view showing an appearance of a functional element unit in the ultrasonic probe of the first embodiment, FIG. 4 is a cross-sectional view of the functional element unit shown in FIG. 3, and FIG. 5 is a functional element unit. FIG. 6 to FIG. 11 are schematic explanatory views of the manufacturing process of the piezoelectric vibrator.

  First, a schematic configuration of an example of an embodiment of an ultrasonic diagnostic apparatus according to the present invention will be described with reference to FIG. As shown in FIG. 1, the ultrasonic diagnostic apparatus 100 includes an ultrasonic probe 101 and an ultrasonic diagnostic apparatus main body 102 to which the ultrasonic probe 101 is connected.

  As shown in FIG. 2, the ultrasonic probe 101 is a sector type probe in this example, and transmits an ultrasonic wave to a subject, and an ultrasonic echo obtained in response to the transmission of the ultrasonic wave. Receive. The detailed configuration of the ultrasonic probe 101 will be described later.

  The ultrasonic diagnostic apparatus main body 102 includes a transmission / reception unit 103, an image processing unit 104, a display unit 105, a control unit 106, and an operation unit 107. The transmission / reception unit 103 drives the ultrasonic probe 101 to transmit ultrasonic waves, and performs signal processing such as phasing addition processing on the ultrasonic echoes received by the ultrasonic probe 101.

  The image processing unit 104 creates an ultrasonic image such as a B-mode image based on the echo signal subjected to signal processing by the transmission / reception unit 103. The ultrasonic image created by the image processing unit 104 is displayed on the display unit 105.

  In the operation unit 107, various instructions are input by the operator. When there is an instruction input, the operation unit 107 outputs an instruction signal to the control unit 106. The control unit 106 controls each unit of the ultrasonic diagnostic apparatus main body 102 based on an instruction signal from the operation unit 107 and a program (program) stored in advance.

  The ultrasonic probe 101 will be described in detail. As shown in FIG. 2, the ultrasonic probe 101 has an acoustic lens unit 10 at the tip. The ultrasonic probe 101 includes a probe housing 11 and a connection cable 12 for connecting to the ultrasonic diagnostic apparatus main body 102.

  A functional element unit 13 is provided in the probe housing 11. The functional element unit 13 will be described in detail with reference to FIGS. The functional element unit 13 includes an acoustic matching layer 14, a piezoelectric vibrator 15, an adhesive layer 16, a reflective layer 17, a backing material layer 18, and a flexible substrate 19. The acoustic matching layer 14, the piezoelectric vibrator 15, and the reflective layer 17 having a rectangular parallelepiped shape that is long in the x-axis direction are stacked in the z-axis direction, which is a direction along the ultrasonic irradiation direction, to form the stacked body 20. Constitute. A plurality of the stacked bodies 20 are arranged in the y-axis direction.

  The acoustic matching layer 14 is bonded to the plate surface on the ultrasonic irradiation direction side of the piezoelectric vibrator 15 (the adhesive layer is not shown). The acoustic matching layer 14 has an acoustic impedance intermediate between the piezoelectric vibrator 15 and the acoustic lens unit 10. The acoustic matching layer 14 has a thickness of approximately ¼ wavelength of the transmitted ultrasonic wave, and suppresses reflection at a boundary surface having different acoustic impedance. The acoustic matching layer 14 is shown as an example of one layer in this example, but may be two layers or multiple layers. The acoustic matching layer 14 is an example of an embodiment of an acoustic matching layer in the present invention.

  The reflective layer 17 is pressure-bonded to the surface of the piezoelectric vibrator 15 opposite to the acoustic matching layer 14 by the adhesive layer 16 made of an epoxy resin adhesive or the like. The reflection layer 17 reflects ultrasonic waves generated toward the reflection layer 17 by elastic vibration of the piezoelectric vibrator 15 in the direction of the subject. The reflective layer 17 is an example of an embodiment of a reflective layer in the present invention.

  Incidentally, when resonance vibration by the piezoelectric vibrator 15 is excited by a voltage applied between a signal electrode 28 (to be described later) of the piezoelectric vibrator 15 and the ground electrode 29, the stationary layer having the reflecting layer 17 as a fixed end is excited. A wave is formed. This standing wave is a standing wave in which the thickness of the piezoelectric vibrator 15 is ¼ wavelength.

  The material of the reflection layer 17 is preferably a material having high acoustic impedance for the purpose of reflecting ultrasonic waves, and tungsten or the like is used. The tungsten has conductivity, and the reflective layer 17 includes a first copper foil layer 22 and a second copper foil layer 23 described later of the flexible substrate 19, a signal electrode 28 of the piezoelectric vibrator 15, and a ground. It has a function of electrically connecting the electrode 29. Thereby, the voltage supplied from the first copper foil layer 22 and the second copper foil layer 23 is applied to the piezoelectric vibrator 15 via the reflective layer 17. In the present invention, the reflective layer 17 is an example of an embodiment of a conductor that is pressure-bonded to a signal electrode and a ground electrode and applies a voltage to a piezoelectric vibrator.

  The reflective layer 17 is mirror-polished on the adhesive surface 17a with the piezoelectric vibrator 15 in order to make the adhesive layer 16 as thin and uniform as possible.

  Excavation holes 21 and 21 are formed at both ends in the length direction of the reflective layer 17, the adhesive layer 16, and the piezoelectric vibrator 15. The excavation holes 21 and 21 are formed by, for example, cutting using a diamond grindstone or the like from the reflective layer 17 side after bonding the piezoelectric vibrator 15 and the reflective layer 17 with the adhesive layer 16.

  The flexible substrate 19 is pressure-bonded to the surface of the reflective layer 17 opposite to the adhesive surface 17a with the piezoelectric vibrator 15 with the backing material layer 18 using an adhesive (adhesive layer). Is omitted). The flexible substrate 19 is pulled out along the side surface in the thickness direction of the backing material layer 18 and connected to the connection cable 12 (the connection structure is not shown).

  The configuration of the flexible substrate 19 will be described. The flexible substrate 19 includes a first copper foil layer 22, a second copper foil layer 23, a first polyimide film layer 24, and a second polyimide as shown in FIG. The film layer 25 is composed of four layers. The first copper foil layer 22 and the second copper foil layer 23 are insulated from each other by the first polyimide film layer 24. The first copper foil layer 22 is formed so as to be positioned closer to both ends of the reflective layer 17 than the excavation holes 21 and 21 in a state where the first copper foil layer 22 is bonded to the reflective layer 17. In addition, the second copper foil 23 is laminated between the first polyimide film layer 24 and the second polyimide film layer 25, and is closer to the center of the reflective layer 17 than the excavation holes 21 and 21. Is also present on the same surface as the first copper foil layer 22 through a through hole H. The first copper foil layer 22 and the second copper foil layer 23 existing on the same surface are insulated from each other by the dividing groove G. The dividing grooves G are formed so as to be located at the excavation holes 21 and 21 in a state where the flexible substrate 19 is bonded to the reflective layer 17. Thereby, said 1st copper foil layer 22 is electrically connected with the edge part side rather than the said excavation holes 21 and 21 in the said reflection layer 17 which has electroconductivity, On the other hand, said 2nd copper foil layer 23 is The reflective layer 17 is electrically connected to an intermediate portion between the excavation holes 21 and 21. Accordingly, the first copper foil layer 22 is electrically connected to the later-described first portions 29a, 29a of the ground electrode 29 in the piezoelectric vibrator 15 via the reflective layer 17, and the second copper foil. The layer 23 is electrically connected to the signal electrode 28 of the piezoelectric vibrator 15 via the reflective layer 17.

  Incidentally, the first copper foil layer 22 connected to the ground electrode 29 is formed on the entire surface of the flexible substrate 19, and the ground electrodes 29 of all the piezoelectric vibrators 15 arranged in the y-axis direction. These are commonly connected. On the other hand, the second copper foil layer 23 is divided into a plurality of pieces in the y-axis direction by copper foil layer dividing grooves (not shown) and has a plurality of copper foil patterns (not shown) formed in the flexible substrate 19. The copper foil pattern is formed for each of the laminates 20 arranged in the y-axis direction.

  The backing material layer 18 is bonded to the flexible substrate 19 or directly formed on the back surface of the flexible substrate 19 to hold the flexible substrate 19. The backing material layer 18 is an example of an embodiment of the backing material layer in the present invention.

  Next, the piezoelectric vibrator 15 will be described with reference to FIG. 5 in addition to FIGS. The piezoelectric vibrator 15 has a conductive layer 27 formed on the surface of the piezoelectric body 26 by sputtering or the like, and the conductive layer 27 constitutes a signal electrode 28 and a ground electrode 29. The piezoelectric body 26, the conductive layer 27, the signal electrode 28, and the ground electrode 29 are examples of embodiments of the piezoelectric body, the conductive layer, the signal electrode, and the ground electrode in the present invention, respectively.

  The signal electrode 28 is formed in an intermediate portion 26 a between the excavation holes 21 and 21 in the piezoelectric body 26. The ground electrode 29 includes first portions 29a and 29a formed on the same surface at the end portions 26b and 26b of the piezoelectric body 26 with the signal electrode 28 and the excavation holes 21 and 21 therebetween. In the piezoelectric body 26, a second portion 29b formed on the surface opposite to the surface on which the first portions 29a, 29a are formed, and in the piezoelectric body 26, the first portions 29a, 29a and the second portion. The third portion 29c is formed on the side surface between the portions 29b. The signal electrode 28 is formed so as to be sandwiched between first portions 29 a and 29 a of the ground electrode 29, and both the electrodes 28 and 29 are electrically insulated by the excavation holes 21 and 21. Yes. The first portions 29 a and 29 a of the signal electrode 28 and the ground electrode 29 are pressure-bonded to the reflective layer 17. The first portion 29a, the second portion 29b, and the third portion 29c are an example of an embodiment of the first portion, the second portion, and the third portion in the present invention. .

  The piezoelectric body 26 includes a filling portion 31 formed by filling a gap 30 with a filling material, and a piezoelectric material portion 32 made of a piezoelectric material such as PZT. The piezoelectric body 26 has a first filling portion 33 described later as the filling portion 31 in the intermediate portion 26a having the signal electrode 28, and is a composite piezoelectric body. The filling portion 31 and the piezoelectric material portion 32 are examples of embodiments of the filling portion and the piezoelectric material portion in the present invention, respectively.

  The filling portion 31 includes a first filling portion 33 provided at an intermediate portion 26a of the piezoelectric body 26, and a second filling portion 34 provided at both ends of the piezoelectric body 26, that is, end portions 26b and 26b. have. The first filling portion 33 and the second filling portion 34 are examples of embodiments of the first filling portion and the second filling portion in the present invention, respectively. A plurality of the first filling portions 33 and the second filling portions 34 are formed, and in this example, the interval T1 between the adjacent first filling portions 33 and the interval between the adjacent second filling portions 34. T2 is equal.

  The first filling part 33 and the second filling part 34 will be further described. First, the second filling portion 34 will be described. When the surface of the piezoelectric body 26 is ground, the second filling portion 34 protrudes on the surface of the piezoelectric body 26 without being ground than the piezoelectric material portion 32. The protrusions 34 a and 34 a are formed by a filler of a material to be formed and project from the surface of the piezoelectric body 26. The protrusions 34a, 34a are an example of the embodiment of the protrusions in the present invention.

  The first filling portion 33 is formed of a filler material that is more excellent in grinding ability than the filler forming the first filling portion 33 when the surface of the piezoelectric body 26 is ground. Unlike the second filling portion 34, the first filling portion 33 does not protrude from the surface of the piezoelectric body 26. Therefore, the surface of the intermediate portion 26a in the piezoelectric body 26 is smooth.

  Here, the filler forming the filling portions 33 and 34 will be specifically described. As the filler forming the filling portions 33 and 34, resins having different grindability are used, and in this example, epoxy resins having different grindability are used. That is, as the filler forming the second filling portion 34, when the surface of the piezoelectric body 26 is ground, the protrusion protruding from the surface of the piezoelectric body 26 without being ground than the piezoelectric material portion 32. The epoxy resin in which 34a and 34a are formed is used. On the other hand, as the filler forming the first filling portion 33, the elastic modulus is lower than the filler forming the second filling portion 34, and the grindability when the surface of the piezoelectric body 26 is ground is as follows. An epoxy resin that is superior to the epoxy resin that forms the second filling portion 34 is used. Further, regarding the filler of the first filling portion 33, the epoxy resin forming the first filling portion 33 is the first resin from the surface of the piezoelectric body 26 when the surface of the piezoelectric body 26 is ground. It is an epoxy resin made of a material having grindability that can suppress the protrusion of the filling portion 33.

  The conductive layer 27 protrudes above the protrusions 34 a and 34 a, and the first portion 29 a and the second portion 29 b of the ground electrode 29 have protrusions 35. This protrusion 35 is an example of the embodiment of the protrusion in the present invention. Here, the adhesive layer 16 is interposed between the piezoelectric vibrator 15 and the reflective layer 17, but the adhesive layer 16 is not interposed between the protrusion 35 and the reflective layer 17. Thus, the protrusion 35 and the reflective layer 17 are in contact with each other and are electrically connected.

  Now, a method for manufacturing the piezoelectric vibrator 15 having the above-described configuration will be described with reference to FIGS. First, as shown in FIG. 6, a first groove 40 having a predetermined depth is formed in the intermediate portion 26a of the piezoelectric body 26 (first groove forming step). The first groove 40 constitutes the gap 30 (see FIGS. 4 and 5) in the piezoelectric vibrator 15. Next, as shown in FIG. 7, the first filling portion 33 is formed by filling the first groove 40 with a filler made of an epoxy resin (first filling portion forming step).

  Next, as shown in FIG. 8, a second groove 41 having a predetermined depth is formed in the end portions 26b, 26b of the piezoelectric body 26 (second groove forming step). This second groove 41 also constitutes the gap 30. Then, as shown in FIG. 9, the second filling portion 34 is formed by filling the second groove 41 with an epoxy resin different from the epoxy resin filled in the first groove 40 as a filler. (Second filling portion forming step). However, at this time, the second filling portion 34 does not have the protrusions 34a and 34a.

  After the epoxy resin constituting each of the filling portions 33 and 34 is cured, as shown in FIG. 10, both surfaces of the piezoelectric body 26 are ground (grinding step). At this time, the second filling portion 34 is compressed because the elastic modulus is lower than that of the piezoelectric material portion 32 and the first filling portion 33, and the piezoelectric material portion 32 and the first filling portion 34 are compressed rather than the second filling portion 34. A large stress is applied to the filling portion 33. Therefore, the piezoelectric material portion 32 and the first filling portion 33 are ground rather than the second filling portion 34, and after the grinding, the second filling portion 34 expands and protrudes on the surface of the piezoelectric body 26, Projections 34a, 34a are formed. On the other hand, the first filling portion 33 is ground in the same manner as the piezoelectric material portion 32. In the piezoelectric body 26, the intermediate portion 26a having the first filling portion 33 has a smooth surface.

  After the grinding step, as shown in FIG. 11, a conductive layer 27 is formed on the surface of the piezoelectric body 26 by sputtering or the like (conductive layer forming step). The conductive layer 27 is formed so that the protrusion 35 is formed on the protrusions 34a and 34a.

  Incidentally, after the piezoelectric vibrator 15 obtained through each of the above steps is bonded by the reflective layer 17 and the adhesive layer 16, cutting is performed from the reflective layer 17 side to form the excavation holes 21 and 21 (FIG. 11). In this case, the signal electrode 28 and the ground electrode 29 are formed. In addition, the piezoelectric vibrator 15 obtained through the above steps is a plate-like body having substantially the same length in the vertical direction and the horizontal direction, and the piezoelectric vibrator 15 made of this plate-like body is replaced with the backing material layer 18. And after laminating | stacking on the said flexible substrate 19, the strip-shaped piezoelectric vibrator 15 arranged in the y-axis direction is formed by dividing | segmenting to a y-axis direction.

  According to the present example described above, the protrusion 35 formed on the ground electrode 29 can ensure conduction between the ground electrode 29 and the reflective layer 17. The lengths of the first portions 29a and 29a of the ground electrode 29 formed on the surface can be made shorter than before. Therefore, the piezoelectric vibrator 15 can be made shorter than before without deteriorating the sensitivity, and thereby the thickness direction (x-axis direction) dimension of the ultrasonic probe 101 can be reduced.

  The first filling portion 33 does not protrude from the surface of the piezoelectric body 26, and the surface of the intermediate portion 26a of the piezoelectric body 26 can be smoothed. Thereby, the unevenness of the surface of the signal electrode 28 can be suppressed to less than a micron order and can be made as smooth as possible, so that the adhesive layer 16 can be made as thin and uniform as possible. Thereby, the adhesive layer 16 does not hinder the function as the fixed end of the reflection layer 17 in the resonance vibration excited by the piezoelectric vibrator 15, and the power of the ultrasonic wave radiated to the subject side is increased. can do. In addition, even when receiving an ultrasonic wave, the adhesive layer 16 does not hinder the function of the reflecting layer 17 as a fixed end. Therefore, an echo signal to be transmitted to the reflecting layer 17 side is transmitted to the piezoelectric vibrator 15. The echo signal received by the piezoelectric vibrator 15 can be increased.

  Furthermore, the smoothness of the surface of the signal electrode 28 is high, while the protrusion 35 is formed on the surface of the ground electrode 29, so that the average thickness of the piezoelectric vibrator 15 is determined by the signal electrode. The end portions 26 b and 26 b having the ground electrode 29 are thicker than the intermediate portion 26 a having 28. Thereby, the stress when the reflective layer 17 is pressure-bonded to the first portion 29a of the signal electrode 28 and the ground electrode 29 can be concentrated on the first portion 29a of the ground electrode 29, and the grounding is performed. The electrode 29 and the reflective layer 17 can be firmly bonded. Therefore, it can be said that the length of the ground electrode 29 can be made shorter than that of the prior art.

(Second embodiment)
Next, a second embodiment will be described. FIG. 12 is a cross-sectional view of a functional element portion in the ultrasonic probe of the second embodiment. In addition, about the structure same as 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the piezoelectric vibrator 50 of this example shown in FIG. 12, the interval T2 between the adjacent second filling portions 34 is narrower than the interval T1 between the adjacent first filling portions 33. Since the interval T1 between the adjacent first filling portions 33 is the same as that in the first embodiment, the interval T2 between the adjacent second filling portions 34 is narrower than that in the first embodiment.

  The piezoelectric vibrator 50 of this example is also manufactured through the same manufacturing process as the manufacturing process of the piezoelectric vibrator 15 of the first embodiment. However, in the second groove forming step, as shown in FIG. 13, the interval T2 between the adjacent second grooves 41 is narrower than the interval T1 between the adjacent first grooves 40. The second groove 41 is formed.

  According to the piezoelectric vibrator 50 of this example, the interval T2 between the adjacent second filling portions 34 is narrower than the interval T1 between the adjacent first filling portions 33, and is adjacent to the first embodiment. Since the interval T2 between the second filling portions 34 is narrow, the interval between the adjacent projecting portions 35 is narrower than in the first embodiment. As a result, the average thickness of both end portions of the piezoelectric vibrator 15 where the first portions 29a, 29a of the ground electrode 29 are formed can be increased, so that the first portion of the ground electrode 29 can be increased. 29a and the reflective layer 17 can be more firmly bonded.

  As mentioned above, although this invention was demonstrated by each said embodiment, of course, this invention can be variously implemented in the range which does not change the main point. For example, the protrusion 35 may be provided only on the first portion 29 a side of the ground electrode 29 formed on the same surface as the signal electrode 28.

  Further, the functional element unit 13 may not have the reflective layer 17. In this case, the flexible substrate 19 is bonded to the surface of the piezoelectric vibrator 15 opposite to the acoustic matching layer 14 using an adhesive.

  The second filling portion 34 may be thicker than the first filling portion 33 so that the tip of the second filling portion 34 can easily protrude from the surface of the piezoelectric body 26 by grinding. In this case, since the thickness of the first filling portion 33 is thinner than that of the second filling portion 34, the surface of the intermediate portion 26 in the piezoelectric body 26 can be easily smoothed by grinding.

1 is a block diagram showing a schematic configuration of an example of an embodiment of an ultrasonic diagnostic apparatus according to the present invention. FIG. 2 is a partially cutaway perspective view showing an appearance of an ultrasonic probe in the ultrasonic diagnostic apparatus shown in FIG. 1. It is a perspective view which shows the external appearance of the functional element part in the ultrasonic probe of 1st embodiment. It is sectional drawing of the functional element part shown in FIG. It is a perspective view which shows the piezoelectric vibrator which comprises a functional element part. It is a schematic explanatory drawing which shows the 1st groove | channel formation process in the manufacturing process of a piezoelectric vibrator. It is a schematic explanatory drawing which shows the 1st filling part formation process in the manufacturing process of a piezoelectric vibrator. It is a schematic explanatory drawing which shows the 2nd groove | channel formation process in the manufacturing process of a piezoelectric vibrator. It is a schematic explanatory drawing which shows the 2nd filling part formation process in the manufacturing process of a piezoelectric vibrator. It is a schematic explanatory drawing which shows the grinding process in the manufacturing process of a piezoelectric vibrator. It is a schematic explanatory drawing which shows the conductive layer formation process in the manufacturing process of a piezoelectric vibrator. It is sectional drawing of the functional element part in the ultrasonic probe of 2nd embodiment. It is a schematic explanatory drawing which shows the 2nd groove | channel formation process in the manufacturing process of the piezoelectric vibrator in 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 Acoustic matching layer 15,50 Piezoelectric vibrator 17 Reflective layer 18 Backing material layer 19 Flexible substrate 26 Piezoelectric body 26a Middle part 26b End part 27 Conductive layer 28 Signal electrode 28a First part 28b Second part 28c Third part DESCRIPTION OF SYMBOLS 29 Ground electrode 30 Gap 31 Filling part 32 Piezoelectric material part 33 First filling part 34 Second filling part 34a Projection part 35 Projection part 40 First groove 41 Second groove 100 Ultrasonic diagnostic apparatus 101 Ultrasonic probe

Claims (11)

A piezoelectric vibrator of an ultrasonic probe in which a signal electrode composed of a conductive layer provided on the surface of a piezoelectric body and a ground electrode are formed on the same surface of the piezoelectric body,
The piezoelectric body is composed of a filling portion formed by filling a gap formed in the piezoelectric body with a filler, and a piezoelectric material portion made of a piezoelectric material,
As the filling portion, a first filling portion provided in a portion having the signal electrode in the piezoelectric vibrator and a portion having the ground electrode formed on the same surface as the signal electrode in the piezoelectric vibrator. A second filling portion formed,
The second filling portion is formed of a filler made of a material that protrudes on the surface of the piezoelectric body without being ground than the piezoelectric material portion when the surface of the piezoelectric body is ground. The first filling portion is more groundable than the filler forming the second filling portion when the surface of the piezoelectric body is ground. It is formed by a filler of excellent material,
The conductive layer on the protrusion in the second filling portion protrudes to form a protrusion on the surface of the ground electrode.
A piezoelectric vibrator of an ultrasonic probe.   2. The piezoelectric vibrator of an ultrasonic probe according to claim 1, wherein the filler in the first filler and the filler in the second filler are resins having different grindability.   3. The piezoelectric vibrator of an ultrasonic probe according to claim 1, wherein a conductor for applying a voltage to the piezoelectric vibrator is surface-bonded to the signal electrode and the ground electrode. The ground electrode is formed on the same surface as the signal electrode at both ends of the piezoelectric body and has a first portion having the protrusion, and on the opposite side to the surface of the piezoelectric body on which the first portion is formed. A second portion formed on the surface, and a third portion formed on a side surface between the first portion and the second portion in the piezoelectric body,
Further, the signal electrode is formed on a surface of an intermediate portion between both end portions of the piezoelectric body so as to be sandwiched between first portions of the ground electrode,
The first filling portion is provided at an intermediate portion between both end portions of the piezoelectric body, while the second filling portion is provided at both end portions of the piezoelectric body. The piezoelectric vibrator of the ultrasonic probe as described in any one of -3.   2. The plurality of first filling portions and the second filling portions, respectively, wherein an interval between the adjacent second filling portions is narrower than an interval between the adjacent first filling portions. The piezoelectric vibrator of the ultrasonic probe as described in any one of -4.   6. A reflection layer for reflecting ultrasonic waves generated by the piezoelectric vibrator is bonded to a surface of the piezoelectric vibrator on which the signal electrode and the ground electrode are formed. A piezoelectric vibrator of the ultrasonic probe according to claim 1.   An ultrasonic probe comprising the piezoelectric vibrator according to claim 1. An acoustic matching layer disposed on the ultrasonic irradiation side opposite to the surface on which the signal electrode and the ground electrode of the piezoelectric vibrator are formed with respect to the piezoelectric vibrator;
A backing material layer disposed on a surface side on which the signal electrode and the ground electrode are formed with respect to the piezoelectric vibrator;
A flexible substrate disposed between the backing material layer and the piezoelectric vibrator and connected to the signal electrode and the ground electrode;
The ultrasonic probe according to claim 7, comprising:   The piezoelectric vibrator includes a conductive reflective layer that is bonded to a surface on which the signal electrode and the ground electrode are formed and reflects ultrasonic waves generated by elastic vibration of the piezoelectric vibrator. The ultrasonic probe according to claim 8, wherein the flexible substrate is connected to the signal electrode and the ground electrode.   An ultrasonic diagnostic apparatus comprising the ultrasonic probe according to claim 7. A first groove forming step of forming a first groove of a predetermined depth in a piezoelectric body made of a piezoelectric material;
A first filling part forming step of filling the first groove with a filler to form a first filling part;
A second groove forming step of forming a second groove having a predetermined depth in a portion different from the portion in which the first groove is formed in the piezoelectric body;
A second filling portion forming step of filling the second groove with a filler to form a second filling portion;
A grinding step of grinding a surface of the piezoelectric body on which the first filling portion and the second filling portion are formed;
A conductive layer forming step of forming a conductive layer to be a signal electrode and a ground electrode on the surface of the piezoelectric body that has undergone the grinding step,
In the second filling portion forming step, the filler filled in the second groove is not ground than the piezoelectric material portion when the surface of the piezoelectric body is ground in the grinding step. It is a material that will protrude on the surface,
Further, in the first filling portion forming step, the filler filled in the first groove has the grindability when the surface of the piezoelectric body is ground in the grinding step to form the second filling portion. Is a material that is better than the filler
In the grinding step, a part of the second filling portion is protruded from the surface of the piezoelectric body to form a protrusion, while grinding is performed so that the first filling portion does not protrude from the surface of the piezoelectric body. ,
In the conductive layer forming step, the conductive layer is formed on the surface of the piezoelectric body so as to project on the projecting portion to form a projecting portion, and the projecting portion of the conductive layer is formed. Is a ground electrode. A method of manufacturing a piezoelectric vibrator in an ultrasonic probe.

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