JP4633571B2 - Array type ultrasonic transducer and manufacturing method thereof - Google Patents

Description

  The present invention relates to an array type ultrasonic transducer using a piezoelectric vibrator.

  2. Description of the Related Art In recent years, an ultrasonic diagnostic method has been widely used in which an ultrasonic endoscope apparatus is used to irradiate a body cavity with ultrasonic waves, and the obtained echo signal is used to image and diagnose a state inside the body. In order to acquire an image in the body cavity by ultrasonic diagnostic methods, an insertion part with an ultrasonic transducer attached to the tip that generates ultrasonic waves or receives ultrasonic waves reflected in the body cavity is inserted into the body cavity. Must.

Conventional array-type ultrasonic transducers are manufactured, for example, by dicing a piezoelectric transducer with an acoustic matching layer bonded thereto to form a plurality of transducer elements and soldering a common ground wiring between the transducer elements. Was. The following document shows an example of a conventional method for manufacturing an array type ultrasonic transducer.
JP 7-298396 A JP 7-298397 A JP 2001-309493 A

  However, in the case of the conventional manufacturing method, the adhesive at the time of bonding protrudes to the portion connecting the common ground line of the piezoelectric vibrator, the protruding adhesive covers the electrode surface, and soldering becomes impossible. When the protruding adhesive is removed before curing, the adhesive at the end is sucked out and the adhesive strength at the end is reduced. If the amount of the adhesive is adjusted in order to prevent such harmful effects, the bonded portion is easily peeled off during dicing processing for forming the ultrasonic transducer element during dicing. Further, after the dicing process, the vibrator element formed by the dicing is easily peeled off. As a result, the yield is greatly reduced.

  In view of the above problems, the present invention provides an array-type ultrasonic transducer configured to prevent the adverse effect of adhesion or to facilitate the wiring of a normal ground line, and a method for manufacturing the same.

According to the first aspect of the present invention, there is provided the piezoelectric element, the first electrode disposed on one surface of the piezoelectric element, and the other surface of the piezoelectric element. And the acoustic matching member bonded to the upper surface of the first electrode with an adhesive, and the upper surface of the first electrode so as to be separated from the acoustic matching member by a predetermined distance. A solder member soldered to the surface, a groove extending from the acoustic matching member to the second electrode and provided at a predetermined interval, and upper surfaces of the plurality of solder members divided by the cutting groove A ground line arranged in close contact with the solder member so as to be connected to the solder member, and the adhesive protruding from between the acoustic matching member and the first electrode, and disposed between the acoustic matching member and the solder member. A reinforcing member, and the reinforcing portion There sites are in close contact can be achieved by providing an ultrasonic transducer, characterized in that the side surface of the acoustic matching member, an upper surface of the first electrode, and a side of the solder member.

According to the second aspect of the present invention, the problem is that, as the portion where the reinforcing member is in close contact, the portion of the upper surface of the solder member where the ground wire is not disposed This can be achieved by providing an ultrasonic transducer according to claim 1 .

According to the third aspect of the present invention, the above-described problem further includes, as the portion where the reinforcing member is in close contact, the side surface of the grounding wire among the upper surface of the solder member. This can be achieved by providing an ultrasonic transducer according to claim 1 or 2 .

The ultrasonic transducer according to any one of claims 1 to 3 , wherein the subject is according to the invention described in claim 4 of the claims, wherein the solder member is made of a lead-free metal. Can be achieved by providing.

According to the invention described in claim 5, the above-described problem is the method of manufacturing an ultrasonic transducer according to claim 1, wherein the first electrode is provided on one surface and the first electrode is provided on the other surface. Preparing a piezoelectric element in which two electrodes are arranged, forming a solder member in a line shape on both ends of the upper surface of the first electrode, and bonding an acoustic matching member at a predetermined distance from the both ends Adhering to the upper surface of the first electrode with an agent, and pressurizing the piezoelectric element and the acoustic matching member so that the adhesive acts on the side surface of the acoustic matching member, the upper surface of the first electrode, and the solder member. A step of protruding the adhesive until it contacts the side surface; a step of curing the adhesive; and a step of removing the adhesive adhered to the upper surface of the solder member to expose the upper surface of the solder member. Ultrasonic Tran characterized by It can be achieved by providing a inducers manufacturing method.

According to the invention as set forth in claim 6 of the present invention, the method of manufacturing an ultrasonic transducer according to claim 5 is characterized in that the removal of the adhesive is performed by grinding. Can be achieved.

According to the seventh aspect of the present invention, after the upper surface of the solder member is exposed , the subject is cut at a predetermined interval from the acoustic matching member to the second electrode. The method of claim 5, further comprising: forming a plurality of transducer elements; and disposing a common ground line so as to be continuous with the upper surfaces of the plurality of cut solder members. This can be achieved by providing a method for manufacturing an ultrasonic transducer .

According to the invention described in claim 8, the above-described problem is the ultrasonic transducer according to any one of claims 1 to 4 or the manufacturing method according to any one of claims 5 to 7. This can be achieved by providing an ultrasonic endoscopic apparatus comprising an ultrasonic transducer manufactured by the above.

  By using the present invention, the acoustic matching layer can be bonded after the solder line is drawn on the electrode, and the surface of the solder layer together with the adhesive can be ground after the adhesive is cured. Further, since the adhesive can be sufficiently applied between the members, it is possible to prevent the bonded members constituting the vibrator element from being peeled off. Also, since the solder layer is ground to eliminate surface irregularities, there is no need to grind the electrodes, and since there are no irregularities on the solder surface, there is no transducer element that is not connected to the common ground wire, and defective transducer elements are generated. It becomes possible to suppress.

  FIG. 1 shows a cross section of an array-type ultrasonic transducer in this embodiment. FIG. 2 shows a top view of FIG. 1 (however, the acoustic lens is omitted). The array-type ultrasonic transducer 1 includes a piezoelectric vibrator 2, electrodes 3 (3a, 3b), a first acoustic matching layer 4, a second acoustic matching layer 5, a solder layer 6, a reinforcing portion 7, a common ground line 8, and an acoustic lens. 9, a flexible printed circuit board (FPC) 10, and a damping layer 11.

  The damping layer 11 is for holding the piezoelectric vibrator 2 on the back surface and for attenuating ultrasonic vibration to obtain a broadband ultrasonic pulse. The FPC 10 is disposed from the side surface to the upper surface of the damping layer 11. Note that a cable for transmitting and receiving signals is provided on the surface of the FPC 10, but it is omitted in the figure. An electrode 3 a is formed on the lower surface of the piezoelectric vibrator 2, and an electrode 3 b is formed on the upper surface.

  In FIG. 2, there are a plurality of grooves (dicing grooves) 21 formed by dicing. As a result of the dicing, portions that are not diced between the dicing grooves 21 are referred to as transducer elements (also simply referred to as elements) 20. The transducer element 20 mainly includes an electrode 3 a, a piezoelectric transducer 2, an electrode 3 b, a first acoustic matching layer 4, a second acoustic matching layer 5, and a common damping layer 11. In FIG. 2, there are transducer elements 20a, 20b, 20c, 20d, and 20e.

When a voltage signal is applied between the electrodes 3a and 3b, the piezoelectric vibrator 2 vibrates and generates ultrasonic waves. The voltage signal is input for each transducer element.
Here, when the first acoustic matching layer 4 and the second acoustic matching layer 5 emit ultrasonic waves as they are in the air, water, living body, etc., the acoustic impedance difference between the piezoelectric vibrator and the air, water, living body, etc. Therefore, the ultrasonic wave bounces off the interface and is not released efficiently, so that it is possible to suppress it and release it efficiently.

  A plurality of transducer elements 20 (20a, 20b, 20c, 20d, 20e) are disposed on the damping layer 11. Solder layers 6 are disposed on the upper left and right ends of the piezoelectric vibrator 2. A reinforcing portion (adhesive) 7 is formed across the first acoustic matching layer 4 and the second acoustic matching layer 5, the electrode 3 b and the solder layer 6. A common ground line 8 is formed adjacent to the reinforcing portion 7. The solder layer 6, the reinforcing portion (adhesive) 7, and the common ground line 8 are provided across the transducer elements 20.

  The solder layer 6 is provided at a location located in the elevation direction of each transducer element (the direction perpendicular to the scanning direction (for example, the direction of scanning from right to left)). A common ground line 8 is provided so as to connect these transducer elements (FIG. 2).

  As described above, a plurality of transducer elements 20 are formed on the damping layer 11, and the acoustic lens 9 is provided so as to cover these transducer elements 20. The acoustic lens 9 not only functions as an acoustic lens, but also functions as a member that covers and protects the array type ultrasonic transducer 1 from the outside.

  3 and 4 show the manufacturing process of the array-type ultrasonic transducer in this embodiment. First, the first acoustic matching layer 4 and the second acoustic matching layer 5 are joined (FIG. 3A). Below, what joined this 1st acoustic matching layer 4 and the 2nd acoustic matching layer 5 is called acoustic matching layer 30. FIG.

  Next, the piezoelectric vibrator 2 having the electrode 3a on the lower surface and the electrode 3b on the upper surface is formed (FIG. 3B). The FPC 10 is adhered to the lower surface of the electrode 3a, and the damping layer 11 is further adhered (FIG. 3C). Also, solder lines 6 are formed on both ends of the upper surface of the electrode 3b to form the solder layer 6 (FIG. 3B). The solder used here is preferably a lead-free metal material in consideration of the burden on the environment.

  Next, an adhesive 31 (for example, epoxy resin) is applied to the upper surface of the electrode 3b to bond the acoustic matching layer 30 (FIG. 3D). When the acoustic matching layer 30 and the electrode 3 b are bonded together while being pressed, an excessive adhesive 31 protrudes, and the reinforcing portion 7 is formed across the side surface of the acoustic matching layer 30, the electrode 3 b, and the solder layer 6. As the adhesive forming the reinforcing portion 7, the same member as the adhesive 31 can be used.

  Thereafter, dicing is performed to form a vibrator element. As a result of the dicing process, a plurality of transducer elements are formed, and grooves generated by the dicing process are formed between the transducer elements.

  Next, the process of FIG. 5 described later is performed to form a common ground line 8 at both ends of each transducer element (end portions in the elevation direction of the transducer elements) (FIG. 4E). The common ground line 8 used here is preferably made of a lead-free metal material in consideration of the burden on the environment.

  After forming the common ground line 8, the acoustic lens 9 is formed on the upper surface of the array-type ultrasonic transducer (FIG. 4 (f)). The acoustic lens 9 also functions as a member that covers the array type ultrasonic transducer 1 from the outside. Therefore, a portion of the acoustic lens 9 other than the portion that actually functions as the acoustic lens (for example, the side surface portion of the array type ultrasonic transducer 1) functions as the protective film 9a. The acoustic lens 9 may also serve as a groove filling member that fills a groove between the transducer elements. In this case, the adhesive 31 and the reinforcing portion 7 are made of the same polymer material (for example, epoxy resin), and the acoustic lens material fills the gap between the transducer elements. Reinforcement to prevent falling.

  FIG. 5 shows details of the manufacturing process of the array-type ultrasonic transducer described in FIGS. 3 and 4. First, a piezoelectric vibrator 2 with a baked Ag electrode is prepared (FIG. 5A). This piezoelectric vibrator 2 is baked with Ag electrodes on the upper and lower surfaces.

  Next, solder lines (also referred to as spare solder) 6 are spread on both ends of the upper surface of the piezoelectric vibrator 2 (FIG. 5B). The solder line 6 can be patterned by a screen printing method. This solder line 6 is for facilitating joining a common ground line to be joined in a later process to the first electrode of the piezoelectric vibrator 2. The solder 6 used here is preferably a lead-free solder, for example, Sn-Ag-Cu type (for example, trade name “LFSOLDER LF-204-1”, manufactured by Tamura Kaken), Sn-Ag type, Sn-Cu system can be used.

  Next, an adhesive 31 is applied to the portion of the upper surface of the piezoelectric vibrator 2 having the solder lines 6 at both ends of the upper surface to be bonded to the acoustic matching layer 30 to bond the acoustic matching layer 30 (FIG. 5). (C)). Due to the pressurization at the time of bonding, excess adhesive 31 protrudes from both the lower surface of the acoustic matching layer 30 and the upper surface of the piezoelectric vibrator 2 to both end portions of the upper surface of the piezoelectric vibrator 2 and covers the periphery of the protruding portion. . The protruding adhesive 31 adheres to the solder line 6, a part of the electrode on the upper surface of the piezoelectric vibrator 2, and the side surface of the acoustic matching layer 30 and fixes them together.

  Next, the portion of the protruding adhesive 31 that covers the solder line 6 is ground using the grinding blade 40 to expose the solder line 6 (FIG. 5D). At this time, the surface of the solder line 6 is also ground. Thereby, the surface of the solder line 6 can be made into a uniform plane.

  Thereafter, dicing is performed to form a plurality of transducer elements, and a common ground line is joined to the upper surfaces of the solder lines 6 at both ends of each transducer element. In the above, the surface of the solder line 6 is formed by grinding into a plane that is substantially parallel to the upper surface of the piezoelectric vibrator 2, and therefore the common ground line joined to the solder line 6 is also the piezoelectric vibrator. It is formed substantially parallel to the upper surface of the.

  By doing so, the side surface of the acoustic matching layer, the surface of the piezoelectric vibrator, and the solder line can be fixed together with the same material at the end of the array type ultrasonic vibrator element in the elevation direction.

  As described above, after the solder line is drawn on the electrode, the acoustic matching layer can be adhered, and the surface of the solder layer together with the adhesive can be ground. Further, since the adhesive can be sufficiently applied between the members, it is possible to prevent the bonded members constituting the vibrator element from being peeled off. Further, since the solder layer is ground, it is not necessary to grind the electrodes, and the height of the solder surface does not become uneven, so that a stable solder line can be formed.

The cross section of the array type ultrasonic transducer in this embodiment is shown. FIG. 2 shows a top view of FIG. 1. The manufacturing process (the 1) of the array type ultrasonic transducer in this embodiment is shown. The manufacturing process (the 2) of the array type ultrasonic transducer in this embodiment is shown. The details of the manufacturing process of the array-type ultrasonic transducer described in FIGS. 3 and 4 are shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Array type ultrasonic transducer 2 Piezoelectric vibrator 3 (3a, 3b) Electrode 4 1st acoustic matching layer 5 2nd acoustic matching layer 6 Solder layer 7 Reinforcement part 8 Common ground line 9 Acoustic lens 10 FPC
11 Damping layer 20 (20a, 20b, 20c, 20d, 20e) Transducer element 30 Acoustic matching layer 31 Adhesive 40 Grinding blade

Claims (8)

  A piezoelectric element;
  A first electrode disposed on one surface of the piezoelectric element;
  A second electrode disposed on the other surface of the piezoelectric element;
  An acoustic matching member adhered to the upper surface of the first electrode by an adhesive;
  A solder member soldered to the upper surface of the first electrode so as to be separated from the acoustic matching member by a predetermined distance;
  A groove extending from the acoustic matching member to the second electrode and provided at a predetermined interval; and
  A grounding wire disposed in close contact with the solder member so as to be continuous with the upper surfaces of the plurality of solder members divided by the cutting grooves;
  A reinforcing member made of the adhesive protruding from between the acoustic matching member and the first electrode, and disposed between the acoustic matching member and the solder member;
  The site where the reinforcing member is in close contact is:
    A side surface of the acoustic matching member;
    An upper surface of the first electrode; and
    An ultrasonic transducer which is a side surface of the solder member.   As a portion where the reinforcing member is in close contact,
  The ultrasonic transducer according to claim 1, further comprising a portion of the upper surface of the solder member where the ground line is not disposed.   As a portion where the reinforcing member is in close contact,
  The ultrasonic transducer according to claim 1, wherein the ultrasonic transducer includes a side surface of the grounding wire in an upper surface of the solder member.   The ultrasonic transducer according to claim 1, wherein the solder member is made of a lead-free metal.   It is a manufacturing method of the ultrasonic transducer according to claim 1,
  Providing a piezoelectric element having a first electrode on one side and a second electrode on the other side;
  Forming a solder member in a line shape on both ends of the upper surface of the first electrode;
  Adhering an acoustic matching member to the upper surface of the first electrode with an adhesive at a predetermined distance from both ends;
  Pressing the piezoelectric element and the acoustic matching member to cause the adhesive to protrude until the adhesive contacts the side surface of the acoustic matching member, the upper surface of the first electrode, and the side surface of the solder member;
  Curing the adhesive; and
  Removing the adhesive bonded to the upper surface of the solder member to expose the upper surface of the solder member;
An ultrasonic transducer manufacturing method comprising:   The method of manufacturing an ultrasonic transducer according to claim 5, wherein the removal of the adhesive is performed by grinding.   After exposing the upper surface of the solder member,
  Cutting at predetermined intervals from the acoustic matching member to the second electrode to form a plurality of transducer elements;
  The method of manufacturing an ultrasonic transducer according to claim 5, further comprising: arranging a common ground line so as to be continuous with the upper surfaces of the plurality of cut solder members.   The ultrasonic transducer according to any one of claims 1 to 4, or
  An ultrasonic endoscope apparatus comprising the ultrasonic transducer manufactured by the manufacturing method according to claim 5.