JP2007158377A - Ultrasonic vibrator and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an ultrasonic vibrator which can easily connect lead wires even if a piezoelectric element is divided to avoid bad influence on a longitudinal vibration due to overlap lateral vibration over the longitudinal vibration, and manufacture a highly reliable ultrasonic vibrator; and also to provide an ultrasonic vibrator manufactured by this method. <P>SOLUTION: The ultrasonic vibrator is manufactured by a step of forming first dicing grooves on an acoustically matched layer and a piezoelectric element plate joined, and dividing them into a plurality of piezoelectric elements; a process of joining the individual divided piezoelectric elements to substrates; a process of coating the surface near the joined portions of the piezoelectric elements and substrates joined, with a conductive film; and a process of forming second dicing grooves between the first dicing groove and the first dicing groove, in the piezoelectric element and the substrate coated with the conductive film, and in the acoustically matched layer, thereby forming a plurality of vibrator elements. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic transducer for transmitting / receiving ultrasonic waves and a method for manufacturing the same.

  Conventionally, in a medical diagnosis, an ultrasonic pulse is repeatedly transmitted from an ultrasonic transducer into a living tissue, and the echo of the ultrasonic pulse reflected from the living tissue is transmitted with the same or separate ultrasonic transducer. An ultrasonic diagnostic apparatus is used that receives information and displays information collected from a plurality of directions in a living body as an ultrasonic tomographic image of a visible image by gradually shifting the direction in which the ultrasonic pulse is transmitted and received. ing. This ultrasonic diagnostic apparatus includes an ultrasonic diagnostic apparatus main body and an ultrasonic transducer for transmitting and receiving ultrasonic waves.

  This ultrasonic vibrator has a piezoelectric vibrator, and this piezoelectric vibrator is divided into strip-like vibrator elements by dicing a plate-like piezoelectric element (piezoelectric vibration material). An acoustic matching layer for matching acoustic impedance is provided on the acoustic radiation surface side of the piezoelectric element, and an acoustic lens is provided on the surface of the acoustic matching layer. Further, a backing material made of rubber or the like having excellent sound absorbing properties is joined to the back side of the piezoelectric element.

  An example of an ultrasonic transducer that transmits and receives ultrasonic waves in the ultrasonic diagnostic apparatus is an array type transducer. The general shape of the piezoelectric element included in the array type vibrator is formed with a width W, a thickness T, and a length L, and electrodes (ground electrodes and signal electrodes) are arranged on the upper and lower surfaces of the width W.

  When a pulse voltage is applied to the electrode, longitudinal vibration corresponding to the thickness T dimension is mainly generated, and lateral vibration corresponding to the width W dimension is also generated secondary. That is, if the width W dimension is constant, lateral vibration is strongly generated, and depending on the shape, it may be superimposed on the longitudinal vibration and adversely affect the longitudinal vibration. For this reason, the piezoelectric element is divided into a plurality of pieces so that the resonance frequency of the lateral vibration does not become a specific frequency.

Here, a general manufacturing process of an ultrasonic transducer in which the piezoelectric element is divided so that the resonance frequency of the lateral vibration does not become a specific frequency will be described (for example, see Patent Document 1).
(1) A backing layer is molded into a predetermined shape (backing material molding step).
(2) Before or after the backing material molding step, a lead wire made of, for example, an FPC (flexible printed circuit) is connected to an electrode provided in a piezoelectric element having a predetermined shape (electrode wiring step).
(3) A piezoelectric element and a backing layer are joined to form a first laminate (piezoelectric vibrator joining step).
(4) The first acoustic matching layer is bonded to the piezoelectric elements constituting the first stacked body to form a vibrator unit set which is the second stacked body (first matching layer bonding step).
(5) A dicing groove is processed from the first acoustic matching layer side of the vibrator unit set to divide the piezoelectric element into a plurality of pieces to produce a vibrator element (dicing step).
(6) The dicing groove is filled with a groove filling material and reinforced (groove filling step).
(7) Joining the second acoustic matching layer to the first acoustic matching layer to form a third laminate (second acoustic matching layer joining step).
(8) An acoustic lens is cast on the third laminate (lens casting step).
(9) The 3rd laminated body which provided the acoustic lens is integrated in a case (case integration process).

The ultrasonic transducer was manufactured through the above steps.
JP 2001-46368 A

  However, if the transducer element is divided so that the resonance frequency of the transverse vibration does not become a specific frequency so that the transverse vibration is not superimposed on the longitudinal vibration and does not adversely affect the longitudinal vibration, it is inevitably divided. As a result, the width of one of the divided transducer elements becomes narrow, which makes it difficult to connect the lead wires.

  In addition, if the width of one of the divided transducer sub-elements is narrow, the reliability of the ultrasonic transducer is reduced because the elasticity of the FPC remains as residual stress when the FPC is directly joined to the sub-element. There was a problem.

  The present invention has been made in view of the above circumstances, and can manufacture a highly reliable ultrasonic transducer that can easily connect lead wires even if the transducer element is finely divided. It is an object of the present invention to provide a method of manufacturing an ultrasonic transducer that can be used, and an ultrasonic transducer manufactured by the manufacturing method.

The present invention employs the following configuration in order to solve the above problems.
That is, according to one aspect of the present invention, the ultrasonic transducer manufacturing method of the present invention is an ultrasonic transducer manufacturing method including a plurality of transducer elements each including a plurality of transducer sub-elements.

  The ultrasonic transducer manufacturing method includes a first dividing step in which a first dicing groove is provided in the bonded acoustic matching layer and the piezoelectric element plate to divide the piezoelectric element into a plurality of piezoelectric elements, and the first division is performed. Piezoelectric element substrate bonding step for bonding each piezoelectric element divided by the process and the substrate, and a conductor film coating for covering the surface in the vicinity of the bonding portion between the piezoelectric element and the substrate bonded by the piezoelectric element substrate bonding step with a conductive film And the piezoelectric element and the substrate covered by the conductor film and the acoustic matching between the first dicing groove and the first dicing groove provided by the first dividing step and the conductor film coating step A second dividing step of forming the plurality of vibrator elements by providing a second dicing groove in the layer.

  The ultrasonic transducer manufacturing method includes a first dividing step in which a first dicing groove is provided in the bonded backing material and the piezoelectric element plate to divide the piezoelectric element into a plurality of piezoelectric elements, and the first dividing step. A piezoelectric element substrate bonding step for bonding each piezoelectric element divided by the substrate and the substrate, and a conductor film coating step for covering the surface in the vicinity of the bonded portion between the piezoelectric element and the substrate bonded by the piezoelectric element substrate bonding step with a conductive film And the piezoelectric element, the substrate, and the backing material, which are covered between the first dicing groove and the first dicing groove provided by the first dividing step and covered with the conductor film by the conductor film coating step, And providing a second dicing groove to form a plurality of transducer elements in the second division step.

  In addition, the method for manufacturing an ultrasonic transducer according to the present invention includes a piezoelectric element bonded to the substrate by the piezoelectric element substrate bonding step after the piezoelectric element substrate bonding step and before the conductor film coating step. It is desirable to further include a masking step for masking the first dicing groove provided on the surface of the first dicing step.

In the method for manufacturing an ultrasonic transducer according to the present invention, it is desirable that the conductor film has a viscosity that does not enter the first dicing groove provided by the first dividing step.
In the method for manufacturing an ultrasonic transducer according to the present invention, the conductor film is preferably a thin film.

  Further, according to one aspect of the present invention, the ultrasonic transducer of the present invention is an array type ultrasonic transducer including a transducer element composed of a plurality of transducer sub-elements, Electrically connecting a piezoelectric element, a substrate bonded adjacent to the piezoelectric element, an electrode formed on one main surface of the piezoelectric element, and an electrode pattern formed on one main surface of the substrate The piezoelectric element is divided into the vibrator sub-element units, and the substrate is divided into the element vibrator units.

  According to the present invention, even if the width of one transducer sub-element is narrow, the degree of freedom in setting the extraction position of the wiring terminal is expanded, so that an ultrasonic transducer can be easily manufactured. .

Further, according to the present invention, since wiring for each transducer element can be performed collectively for all transducer sub-elements, it is possible to easily manufacture an ultrasonic transducer.
In addition, according to the present invention, since a thick film or a thin film (conductive film) of conductive resin is used as a conductive wire, it is possible to manufacture an ultrasonic vibrator with a reduced wiring space.

  Further, according to the present invention, since no bending stress or the like of FPC remains, it is possible to manufacture a highly reliable ultrasonic vibrator.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a first embodiment to which the present invention is applied will be described with reference to FIGS.
FIG. 1 is a flowchart showing a procedure of a method of manufacturing an ultrasonic transducer in the first embodiment, and FIG. 2 is a perspective view for explaining an acoustic matching layer piezoelectric element joining step. FIG. 4 is a perspective view for explaining the first dividing step, FIG. 4 is a top view for explaining the first dividing step, and FIG. 5 is for explaining the piezoelectric element substrate bonding step. FIG. 6 is a top view for explaining a piezoelectric element substrate bonding step, FIG. 7 is a perspective view for explaining a masking step, and FIG. 8 is a first embodiment. 9 is a top view for explaining the conductor film coating step in FIG. 9, FIG. 9 is a top view for explaining the second dividing step in the first embodiment, and FIG. 10 is a view after removing the mask member. It is a top view which shows a state.

  First, in the acoustic matching layer piezoelectric element joining step in step S11 of FIG. 1, the acoustic matching layer 21 and the piezoelectric element 22 are joined as shown in FIG. In the piezoelectric element 22, for example, a piezoelectric element radiation surface electrode (an electrode to which a ground lead wire is connected) and a piezoelectric element back electrode (an electrode to which a drive lead wire is connected) are formed by silver baking.

  In the first dividing step of step S12 of FIG. 1, as shown in FIGS. 3 and 4, the acoustic matching layer 21 and the piezoelectric element 22 joined by the acoustic matching layer piezoelectric element joining step of step S11 are combined with a dicing machine. The first dicing grooves 31 having a predetermined pitch are provided using As a result, the bonded acoustic matching layer 21 and the piezoelectric element 22 are divided into a plurality of piezoelectric elements 32.

  Then, in the piezoelectric element substrate bonding step in step S13 in FIG. 1, as shown in FIGS. 5 and 6, ultrasonic waves are transmitted to each piezoelectric element 32 divided in the first division step in step S12. For example, a transmission cable for transmitting a drive signal for receiving a received signal generated by the received ultrasonic wave or a substrate 51 to which another substrate such as an FPC is connected is joined. The substrate 51 can be a three-dimensional substrate, an alumina substrate, a glass epoxy substrate, a rigid flexible board, an FPC, or the like. Electrode patterns 52 are formed on the substrate 51 at a predetermined pitch (a pitch corresponding to the arrangement pitch of transducer elements 82 described later). The electrode pattern 52 may be only on the front side of the substrate 51, or may be formed from the back surface to the front surface via the side surface. The height of the conductor surface of the substrate 51 shown in FIG. 5 is substantially the same as that of each piezoelectric element 32. However, when using a conductive resin, a conductive thin film, a thin (for example, about 8 micrometers) metal foil, or a flexible printed circuit board using this, the height between each piezoelectric element 32 and the surface of the conductor surface of the substrate 51 is: It does not matter if there is a difference of about several tens of micrometers (whichever is higher).

  Next, in the masking process of step S14 in FIG. 1, as shown in FIG. 7, the surface of each piezoelectric element 32 bonded to the substrate 51 in the piezoelectric element substrate bonding process of step S13, and the first of step S12. The mask member 121 masks the first dicing groove 31 provided by the dividing step. As the mask member 121, a printing screen represented by a metal mask or a mesh mask, a metal plate such as stainless steel, steel, nickel, or a copper alloy, polyimide, PTFE (polytetrafluoroethylene), PET (polyethylene terephthalate), or the like. Materials such as tape, PET, quartz glass, ceramics, and FRP (Fiber Reinforced Plastic) using a resin as a base material can be used.

  Next, in the conductor film coating process in step S15 in FIG. 1, as shown in FIG. 8, the vicinity of the joint portion of both the piezoelectric element 32 and the substrate 51 joined in the piezoelectric element substrate joining process in step S13. The surface in the vicinity of the portion masked by the mask member 121 in step S14 is covered with the conductor film 71 made of a conductor thick film or a conductor thin film.

  When the conductor film 71 is formed, in the second dividing step of step S16 in FIG. 1, as shown in FIG. 9, the first dicing groove 31 provided in the first dividing step of step S12 and A dicing machine is used to connect the piezoelectric element 32, the substrate 51, and the acoustic matching layer 21 covered with the conductor film 71 by the conductor film coating process in step S15 between the first dicing groove 31 and a predetermined pitch. A plurality of transducer elements 151 are formed by providing the second dicing grooves 81.

  Finally, in the mask member removing process in step S17 of FIG. 1, as shown in FIG. 10, the mask member 121 is removed, thereby providing a plurality of transducer elements 151 each including two transducer sub-elements. An ultrasonic transducer can be manufactured.

  Next, a second embodiment to which the present invention is applied will be described with reference to FIGS. The description will focus on the differences from the first embodiment, and the description of common parts will be omitted.

  FIG. 11 is a flowchart showing the procedure of the method of manufacturing an ultrasonic transducer in the second embodiment, and FIG. 12 is a perspective view for explaining a conductor film coating process in the second embodiment. FIG. 13 is a perspective view for explaining the second dividing step in the second embodiment, and FIG. 14 is a top view for explaining the second dividing step in the second embodiment. FIG. 15 is a perspective view showing one transducer element.

  The flowchart shown in FIG. 11 differs from the flowchart shown in FIG. 1 in that the masking process in step S14 and the mask member removing process in FIG. 17 shown in FIG. That is, one feature of the method for manufacturing an ultrasonic transducer in the second embodiment is that no masking process is required.

  Specifically, following the piezoelectric element substrate bonding step of step S13, in the conductor film coating step of step S15, as shown in FIG. 12, the piezoelectric element 32 and the substrate bonded by the piezoelectric element substrate bonding step of step S13. The surface in the vicinity of both joint portions with 51 is covered with a conductor film 71. The conductive film 71 is formed of a conductive thin film made of conductive paint, conductive resin, conductive adhesive, etc., a conductive thin film by plating or sputtering, vapor deposition, CVD (Chemical Vapor Deposition), etc. Is possible.

  When the conductor film 71 is cured, in the second dividing step of step S16 in FIG. 11, as shown in FIGS. 13 and 14, the first dicing provided by the first dividing step of step S12 is performed. A dicing machine is used between the groove 31 and the first dicing groove 31 and the piezoelectric element 32, the substrate 51, and the acoustic matching layer 21 covered with the conductor film 71 by the conductor film coating process of step S15. A plurality of transducer elements 82 are formed by providing second dicing grooves 81 having a predetermined pitch.

  Thus, two vibrations connected to one transmission cable (not shown) for transmitting a drive signal for transmitting an ultrasonic wave or receiving a reception signal generated by the received ultrasonic wave An ultrasonic transducer including a plurality of transducer elements 82 composed of child sub-elements can be manufactured.

FIG. 15 is a perspective view showing one transducer element.
In FIG. 15, the transducer element 82 is divided by the second division step in step S <b> 16 of FIG. 11, and the divided acoustic matching layer 21, piezoelectric element 22, substrate 51 having electrode pattern 52, conductor The film 71 is formed, and the first dicing groove 31 has two piezoelectric element sub-elements.

  If the viscosity of the conductive adhesive or conductive paint is 3000 cps or more and the width of the first dicing groove 31 is 100 micrometers or less, the conductor film 71 is formed in the first dicing groove 31. Since it becomes difficult to enter, there is no need to cover the first dicing groove 31 with any means. In particular, when the conductive film 71 is formed by a printing method using a thixotropic conductive adhesive or conductive paint, it is possible to reliably prevent the first dicing groove 31 from entering.

  The embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the above-described embodiments, and various changes, modifications, and the like can be made without departing from the scope of the present invention. Is possible.

  For example, in each of the above-described embodiments, a transducer element including two transducer sub-elements is used as an example. However, the transducer element includes three or more transducer sub-elements. May be.

  In addition, the electrode material of the piezoelectric element is not limited to the silver electrode, and an electrode formed by a technique such as sputtering, vapor deposition, CVD, plating using a metal material such as gold, chromium, copper, nickel, etc. can be used. It is.

  Similarly, the shape of the mask is limited to the shape shown in the present application as long as it has a shape or function that covers the portion of the first dicing groove where the conductor film is formed as shown in the above embodiment. For example, a shape used as a printing mask or a thin film mask, such as a comb-like shape, is applicable.

  Similarly, in each of the above embodiments, an example in which the piezoelectric element plate and the substrate are placed on the acoustic matching layer is described. However, a backing material that is another main acoustic member, a temporary fixing plate that is removed when completed, etc. Even if the piezoelectric element and the substrate are placed on a member other than the acoustic matching layer, the same process and structure can be taken.

It is the flowchart which showed the procedure of the manufacturing method of the ultrasonic transducer | vibrator in 1st Embodiment. It is a perspective view for demonstrating an acoustic matching layer piezoelectric element joining process. It is a perspective view for demonstrating a 1st division | segmentation process. It is a top view for demonstrating a 1st division | segmentation process. It is a perspective view for demonstrating a piezoelectric element board | substrate joining process. It is a top view for demonstrating a piezoelectric element board | substrate joining process. It is a perspective view for demonstrating a masking process. It is a top view for demonstrating the conductor film coating process in 1st Embodiment. It is a top view for demonstrating the 2nd division | segmentation process in 1st Embodiment. It is a top view which shows the state after mask member removal. It is the flowchart which showed the procedure of the manufacturing method of the ultrasonic transducer | vibrator in 2nd Embodiment. It is a perspective view for demonstrating the conductor film coating process in 2nd Embodiment. It is a perspective view for demonstrating the 2nd division | segmentation process in 2nd Embodiment. It is a top view for demonstrating the 2nd division | segmentation process in 2nd Embodiment. It is a perspective view which shows one vibrator | oscillator element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Acoustic matching layer 22 Piezoelectric element board 31 1st dicing groove 32 Piezoelectric element 51 Substrate 52 Electrode pattern 71 Conductive film 81 2nd dicing groove 82 Transducer element 121 Mask member 151 Transducer element

Claims (6)

In the manufacturing method of an ultrasonic transducer provided with a plurality of transducer elements composed of a plurality of transducer sub-elements,
A first dividing step in which a first dicing groove is provided in the bonded acoustic matching layer and the piezoelectric element plate to divide into a plurality of piezoelectric elements;
A piezoelectric element substrate bonding step of bonding each piezoelectric element divided by the first dividing step and the substrate;
A conductor film coating step of covering the surface in the vicinity of the bonded portion of the piezoelectric element and the substrate bonded by the piezoelectric element substrate bonding step with a conductor film;
Between the first dicing groove and the first dicing groove provided by the first dividing step, and between the piezoelectric element covered by the conductor film by the conductor film coating step, the substrate, and the acoustic matching layer A second dividing step of forming the plurality of transducer elements by providing a second dicing groove;
A method for manufacturing an ultrasonic transducer, comprising: In the manufacturing method of an ultrasonic transducer provided with a plurality of transducer elements composed of a plurality of transducer sub-elements,
A first dividing step in which a first dicing groove is provided in the bonded backing material and the piezoelectric element plate and divided into a plurality of piezoelectric elements;
A piezoelectric element substrate bonding step of bonding each piezoelectric element divided by the first dividing step and the substrate;
A conductor film coating step of covering the surface in the vicinity of the bonded portion of the piezoelectric element and the substrate bonded by the piezoelectric element substrate bonding step with a conductor film;
Between the first dicing groove and the first dicing groove provided in the first dividing step, and on the piezoelectric element covered with the conductor film by the conductor film coating step, the substrate, and the backing material. A second dividing step of forming the plurality of transducer elements by providing two dicing grooves;
A method for manufacturing an ultrasonic transducer, comprising: After the piezoelectric element substrate bonding step, before the conductor film coating step,
A masking step of masking a first dicing groove provided by the first dividing step on the surface of each piezoelectric element bonded to the substrate by the piezoelectric element substrate bonding step;
The method for manufacturing an ultrasonic transducer according to claim 1, further comprising:   The method of manufacturing an ultrasonic transducer according to claim 1, wherein the conductive film has a viscosity that does not enter a first dicing groove provided in the first division step.   The method for manufacturing an ultrasonic transducer according to claim 1, wherein the conductor film is a thin film. An array-type ultrasonic transducer comprising a transducer element composed of a plurality of transducer sub-elements,
The transducer element is
The piezoelectric element;
A substrate bonded adjacent to the piezoelectric element;
An electrode formed on one main surface of the piezoelectric element;
A conductive film that electrically connects the electrode pattern formed on one main surface of the substrate;
The piezoelectric element is divided into the vibrator sub-element units,
The ultrasonic transducer, wherein the substrate is divided into transducer elements.