JP2004056504A - Ultrasonic probe and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely connect a lead to each piezoelectric element even when a back intermediate layer is provided in an ultrasonic probe. <P>SOLUTION: The back intermediate layer 10B is provided on a back side of each piezoelectric element 26. A backing 22 is provided on the back side of each back intermediate layer 10B. A conductor 18 is provided piercing the backing and each back intermediate layer 10B. The conductor 18 functions as a signal lead. The back intermediate layer 10B functions as a back side matching layer or a back side reflection layer. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic probe and a method of manufacturing the same, and more particularly, to an ultrasonic probe having a backing having a built-in lead array and a method of manufacturing the same.
[0002]
[Prior art]
For example, in a 2D array vibrator including a plurality of vibrating elements, a backing with a built-in lead array is used to connect leads (signal leads) to each vibrating element (for example, see Japanese Patent No. 3279375). Here, a plurality of electrode pads connected to a plurality of leads are formed on the upper surface and the lower surface of the backing. Each electrode pad on the upper surface is joined to the electrode surface (lower surface) of each piezoelectric element. Thus, each lead is electrically connected to each piezoelectric element.
[0003]
Conventionally, a matching layer is provided on the front side of each piezoelectric element. This is for matching the acoustic impedance of the piezoelectric element with the acoustic impedance of the living body. On the other hand, it has been proposed to provide a back intermediate layer on the back side for each piezoelectric element. Here, it is considered that the back intermediate layer can function as a back side matching layer or a back side reflecting layer depending on its characteristics.
[0004]
[Problems to be solved by the invention]
However, when the back intermediate layer is provided, it is impossible to electrically connect a plurality of leads provided in the backing to each piezoelectric element as it is. Also, a rational manufacturing process for providing such a back intermediate layer is required.
[0005]
An object of the present invention is to ensure that leads can be connected to each piezoelectric element even when a back intermediate layer is provided.
[0006]
It is another object of the present invention to provide a process for manufacturing an ultrasonic probe having a plurality of back intermediate layers and a backing with a built-in lead array.
[0007]
[Means for Solving the Problems]
(1) In order to achieve the above object, the present invention provides a plurality of piezoelectric elements and a back side of the plurality of piezoelectric elements, which absorbs ultrasonic waves radiated from the plurality of piezoelectric elements to the back side. A backing, a plurality of back intermediate layers provided between the respective piezoelectric elements and the backing, and a plurality of back intermediate layers electrically connected to the plurality of piezoelectric elements through the backing and the plurality of back intermediate layers. And a lead.
[0008]
According to the above configuration, a plurality of leads are provided so as to penetrate the backing and the plurality of back intermediate layers, whereby a signal can be supplied to each piezoelectric element or a ground can be connected. The present invention can be applied to various array transducers such as a 1D array transducer, a 1.5D array transducer, and a 2D array transducer (including a sparse array transducer).
[0009]
Preferably, each of the leads includes a first lead portion inserted into the backing and a second lead portion inserted into each of the back intermediate layers, and the first lead portion and the second lead The part consists of one conductor. According to this configuration, there is no need to connect the first lead portion and the second lead portion.
[0010]
Preferably, when the acoustic impedance of each of the piezoelectric elements is Z1, the acoustic impedance of each of the back intermediate layers is Z2, and the acoustic impedance of the backing is Z3,
Z1>Z2> Z3 (1)
Holds, and each of the back intermediate layers functions as a back side matching layer.
[0011]
According to this configuration, the back intermediate layer functions as a matching layer for matching acoustic impedance, that is, it is possible to further enhance the ultrasonic wave absorbing action in the backing.
[0012]
Preferably, when the acoustic impedance of each of the piezoelectric elements is Z1, the acoustic impedance of each of the back intermediate layers is Z2, and the acoustic impedance of the backing is Z3,
Z1>Z3> Z2 (2)
Holds, and each of the rear intermediate layers functions as a rear reflective layer.
[0013]
According to this configuration, the back intermediate layer functions as a reflective layer that actively utilizes the difference in acoustic impedance. That is, a part of the ultrasonic wave radiated to the back side is reflected forward, and the sound pressure of the ultrasonic wave radiated forward from the piezoelectric element can be increased. In any case, in order for the back intermediate layer to function as a matching layer or a reflecting layer, it is desirable to make the thickness appropriate in relation to the wavelength of the ultrasonic wave.
[0014]
Preferably, each of the rear intermediate layers is formed of a conductive member, and each of the rear intermediate layers is also used as an electrode pad of each of the piezoelectric elements. According to this configuration, it is not necessary to separately provide an electrode pad for each piezoelectric element, so that the structure can be simplified and the manufacturing cost can be reduced.
[0015]
(2) Further, the present invention provides a plurality of piezoelectric elements, a backing provided on the back side of the plurality of piezoelectric elements and absorbing ultrasonic waves radiated from the plurality of piezoelectric elements to the back side, The semiconductor device is characterized by including a plurality of back intermediate layers functioning as electrode pads provided between the element and the backing, and a plurality of leads electrically connected to the plurality of back intermediate layers.
[0016]
In the above configuration, each lead may penetrate both the backing and each rear intermediate layer, or may penetrate only the backing and be electrically connected to the lower surface of each rear intermediate layer. In any case, each lead is electrically connected to each back intermediate layer.
[0017]
(3) The present invention also provides a step of bridging a plurality of conductors between the rear intermediate member and the substrate, a step of providing a backing between the rear intermediate member and the substrate, and an upper surface of the rear intermediate member. A step of providing a piezoelectric member on the side, and a step of cutting the piezoelectric member and the rear intermediate member to thereby form a plurality of piezoelectric elements and a plurality of rear intermediate layers.
[0018]
According to the above configuration, the backing is formed in a state where a plurality of conductive wires are bridged between the rear intermediate member and the substrate, and the piezoelectric member and the rear intermediate member are cut together. Each back intermediate layer desirably has insulating properties.
[0019]
Desirably, between the step of providing the backing and the step of providing the piezoelectric member, the method includes a step of providing an electrode member on the upper surface of the rear intermediate member, and the cutting allows the plurality of piezoelectric elements, the plurality of electrode pads and The plurality of back intermediate layers are formed.
[0020]
Preferably, in the step of providing the backing, a liquid backing material is filled between the back intermediate member and the substrate, and is cured, and at this time, the back intermediate member and the substrate are separated from each other. It functions as a positioning member for the plurality of conductors. According to this configuration, the positioning of each conductor can be easily performed.
[0021]
Preferably, a plurality of through-holes are formed in the rear intermediate member in advance, and each of the conductive wires is inserted into each of the through-holes.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a flowchart showing a main part of a manufacturing process of an ultrasonic probe according to the present invention. Hereinafter, the manufacturing process will be described with reference to the drawings, and the structural characteristics of the ultrasonic transducer included in the ultrasonic probe according to the present embodiment will also be described.
[0024]
The ultrasonic probe according to the present embodiment is connected to an ultrasonic diagnostic apparatus main body via a cable. In addition, during use, it is used in contact with the body surface of a living body, and in that state, ultrasonic waves are transmitted and received. Of course, the ultrasonic probe according to the present embodiment may be inserted into a body cavity.
[0025]
The step of S101 shown in FIG. 1 will be described. In FIG. 2, the rear intermediate member 10 and the substrate 12 are positioned at a predetermined interval. Here, the rear intermediate member 10 is a member for forming a rear intermediate layer for each vibration element, and the rear intermediate member 10 is configured as a plate-shaped member in the example shown in FIG. The rear intermediate member 10 can be made of, for example, a material in which an inorganic powder or the like is mixed into an epoxy resin. A plurality of through holes 10A are formed in the rear intermediate member 10 so as to correspond to the two-dimensional arrangement of the vibration elements. The through-hole 10A can be formed by using, for example, laser processing or an ultra-fine drill. The rear intermediate member 10 is a member having an insulating property in the example shown in FIG. 2, but may be formed of a conductive member as described later. The thickness of the back intermediate member 10 is set in relation to the wavelength of the ultrasonic wave, and preferably, the thickness is set to an odd multiple of the quarter wavelength.
[0026]
The above-described substrate 12 is configured as a plate-like member having an insulating property. Also, a plurality of through holes 12A are formed in the substrate 12 in the same arrangement as the plurality of through holes 10A formed in the rear intermediate member 10. Of course, a plurality of through holes 12A may be formed in the substrate 12 in an arrangement different from the plurality of through holes 10A formed in the rear intermediate member 10. A plurality of electrode pads 14 are provided on the back side of the substrate 12, that is, on the lower side in the figure, corresponding to the plurality of through holes 12A. This electrode pad 14 is formed of a conductive member. A through hole 14A is formed at the center of each electrode pad 14, and each through hole 12A formed in the substrate 12 and the through hole 14A formed in the electrode pad 14 communicate with each other.
[0027]
In the step of S101 shown in FIG. 1, as shown in FIG. 2, in a state where the back intermediate member 10 and the substrate 12 are positioned at a predetermined interval, a plurality of conductive wires 18 are laid between them. Specifically, one end of the conducting wire 18 is pierced into each through hole 10A formed in the rear intermediate member 10, and the other end of the conducting wire 18 is pierced into each through hole 12A (and the through hole 14A) of the substrate 12. Passed through.
[0028]
Then, after performing, for example, soldering or the like to the through hole 14A of each electrode pad 14, a portion of each conductive wire 18 that is drawn downward from the electrode pad 14 is cut. FIG. 2 shows this state, and reference numeral 16 denotes a soldered portion. Of course, such cutting of the drawn-out portion of the conductive wire 18 may be performed in a later step.
[0029]
In S102 of FIG. 1, the space 20 between the rear intermediate member 10 and the substrate 12 shown in FIG. 2 is surrounded by a frame (not shown), and the space 20 is filled with a backing material. FIG. 2 does not show the positioning member holding the rear intermediate member 10 and the substrate 12.
[0030]
In FIG. 2, the through-hole 10A, the through-hole 12A, and the through-hole 14A are shown in large size for understanding of the invention. Is set to be slightly larger than the diameter of. The through holes 10A, 12A, and 14A are not shown in FIGS.
[0031]
Here, the backing material will be described. In the present embodiment, for example, a material in which an epoxy resin is mixed with tungsten powder or the like can be used as the backing material. Here, the purpose of mixing tungsten powder or the like into the epoxy resin is to obtain a desired acoustic impedance and a desired attenuation rate. In the above-mentioned S102, after the filled backing material is vacuum-degassed, the backing material is cured, for example, at 80 ° C. for 5 hours. Then, the backing material is processed so as to obtain a predetermined outer shape.
[0032]
In S103 of FIG. 1, the electrode member 24 is formed on the upper surface of the rear intermediate member 10, as shown in FIG. Although the electrode member 24 is configured as a plate-like member in the example shown in FIG. 3, an electrode member 24, that is, an electrode pad may be provided for each vibration element at this stage. The electrode member 24 can be formed by using, for example, an electroless plating method, a vapor deposition method, a sputtering method, or application of a conductive paint.
[0033]
As shown in FIG. 3, the electrode member 24 is electrically connected to the upper end of the conductor 18 which functions as a signal lead later. Each conducting wire 18 is roughly divided into a first portion 18A and a second portion 18B, and the first portion 18A passes through the backing 22 and the second portion 18B passes through the back intermediate member 10. . Compared to the case where the conductors are individually buried for each of these portions, in the present embodiment, there is an advantage that the conductors can be collectively provided for both the back intermediate member 10 and the backing 22. .
[0034]
In the step of S104 shown in FIG. 1, a plate-shaped piezoelectric member (piezoelectric plate) is adhered to the upper surface of the block body shown in FIG. In this case, for example, a conductive adhesive or a non-conductive adhesive is used. The piezoelectric member has a lower electrode layer functioning as a signal electrode and an upper electrode layer functioning as a ground electrode, as described later. These electrode layers can be formed in a film shape using, for example, an evaporation method or a sputtering method.
[0035]
Next, in the step of S105 in FIG. 1, a plurality of divided grooves are formed in a matrix along the vertical and horizontal directions from the upper surface side of the workpiece after the piezoelectric member is bonded.
[0036]
Due to the formation of the division grooves, the back intermediate member 10 is divided into a plurality of back intermediate layers, and the electrode member 24 shown in FIG. 3 is also divided into a plurality of electrode pads. Further, the above-described piezoelectric member is also divided into a plurality of piezoelectric elements.
[0037]
In S106 of FIG. 1, ground leads are provided on the upper surface side of the plurality of piezoelectric elements. This ground lead is made of, for example, a copper foil having a planar shape. An upper electrode layer provided on each piezoelectric element is electrically connected to the ground lead. Thereafter, a plate-shaped alignment member is bonded to the upper surface side of the ground lead. Then, in S107, a division groove is formed in the alignment member in a matrix along the vertical and horizontal directions, whereby a plurality of matching layers are formed corresponding to the plurality of vibration elements. Become.
[0038]
FIG. 4 shows a state after the process of S107 is performed. In the above-described step S105, the dividing groove 100 is formed using, for example, a dicing saw, and in the above-described step S107, the dividing groove 102 is formed using a dicing saw in the same manner as described above. Looking at each vibration element, a back intermediate layer 10B is provided on the upper surface side of the backing 22, and an electrode pad 24A is formed on the upper surface side. A piezoelectric element 26 is provided on the upper surface side of the electrode pad 24A. The lower electrode layer 26B of the piezoelectric element 26 is electrically connected to the electrode pad 24A. A ground lead 28 is provided on the upper surface side of the piezoelectric element 26, and the ground lead 28 is electrically connected to the upper electrode layer 24A of the piezoelectric element 26. A matching layer 30 is provided on the upper surface side of the ground lead 28.
[0039]
That is, by performing each of the above-described steps, for example, a 2D array vibrator can be configured. The above-mentioned division groove 100 functions as a groove for electrically and acoustically separating the transducer elements from each other, and has electric and acoustic isolation in the separation groove 100 as necessary. The member may be filled. This is the same for the dividing groove 102.
[0040]
Next, the function of each back intermediate layer 10B will be described. The acoustic impedance of the piezoelectric element 26 is Z1, the acoustic impedance of each back intermediate layer 10B is Z2, and the acoustic impedance of the backing 22 is Z3.
[0041]
In this case, when each back intermediate layer 10B functions as a back side matching layer, each acoustic impedance is set so that the relationship of Z1>Z2> Z3 is satisfied.
[0042]
On the other hand, when each rear intermediate layer 10B functions as a rear reflective layer, the acoustic impedance of each member is set so that the relationship of Z1>Z3> Z2 is satisfied.
[0043]
When each back intermediate layer 10B functions as a back side matching layer, the function of absorbing unnecessary ultrasonic waves in the backing 22 can be further enhanced. On the other hand, when each back intermediate layer 10B functions as a back side reflection layer. It is also possible to further increase the sound pressure of the ultrasonic wave radiated forward. In order to further produce such an effect, it is desirable that the thickness of the rear intermediate layer 10B be set to an odd multiple of a quarter of the wavelength of the ultrasonic wave.
[0044]
FIG. 5 shows a main configuration of another embodiment. In this embodiment, a conductive member is used as the rear intermediate layer 30. The lead 18 includes a first portion 18A inserted into the backing and a second portion 18B inserted into the back intermediate layer 30. Since the back intermediate layer 30 is made of a conductive member, the electrode pad 24A shown in FIG. 4 and the like can be eliminated, and the structure can be simplified accordingly, and the manufacturing process can be simplified. There is.
[0045]
FIG. 6 shows still another embodiment. In the configuration example shown in FIG. 6, a conductive back intermediate layer 30 is used as in the example shown in FIG. The upper end of 18 reaches only the lower surface level of the rear intermediate layer 30 and does not penetrate the entire rear intermediate layer 30.
[0046]
When the backing 22 is formed of a conductive member, it is desirable to provide an insulating coating layer outside the conductive wire.
[0047]
In addition, the same member as the back surface intermediate member 10 may be filled and hardened in the through hole 10A shown in FIG. 2, and similarly, the through hole 12A in the substrate 12 is similar to the substrate 12. The member may be filled and hardened. Furthermore, in the present embodiment, only one back intermediate layer is provided, but a configuration in which a plurality of back intermediate layers are stacked may be adopted. In this case, the acoustic impedance of each layer may be varied stepwise. In such a case, it is desirable that the thickness of each layer be an odd multiple of 1/4 of the wavelength of the ultrasonic wave.
[0048]
【The invention's effect】
As described above, according to the present invention, a lead can be reliably connected to each piezoelectric element even when a back intermediate layer is provided. Further, according to the present invention, it is possible to provide a process for manufacturing an ultrasonic probe having a plurality of back intermediate layers and a backing with a built-in lead array.
[Brief description of the drawings]
FIG. 1 is a flowchart for explaining a manufacturing process of an ultrasonic probe according to the present invention.
FIG. 2 is a view for explaining a step of inserting a conducting wire.
FIG. 3 is a view for explaining a step of forming an electrode member.
FIG. 4 is a diagram showing a finally formed two-dimensional array transducer.
FIG. 5 is a diagram showing a configuration of another embodiment.
FIG. 6 is a diagram showing a configuration of still another embodiment.
[Explanation of symbols]
Reference Signs List 10 back intermediate member, 12 substrate, 14 electrode pads, 18 conductors, 22 backing, 24 electrode members, 26 piezoelectric element, 28 ground lead, 100, 102 division groove.

Claims (10)

A plurality of piezoelectric elements,
A backing provided on the back side of the plurality of piezoelectric elements and absorbing ultrasonic waves emitted from the plurality of piezoelectric elements to the back side,
A plurality of back intermediate layers provided between each of the piezoelectric elements and the backing,
A plurality of leads electrically connected to the plurality of piezoelectric elements through the backing and the plurality of back intermediate layers,
An ultrasonic probe comprising: The ultrasonic probe according to claim 1,
Each of the leads is
A first lead portion inserted into the backing;
A second lead portion inserted through each of the rear intermediate layers;
Consists of
The ultrasonic probe according to claim 1, wherein the first lead portion and the second lead portion are formed of one conductive wire. The ultrasonic probe according to claim 1,
When the acoustic impedance of each piezoelectric element is Z1, the acoustic impedance of each back intermediate layer is Z2, and the acoustic impedance of the backing is Z3, the relationship of Z1>Z2> Z3 holds,
An ultrasonic probe, wherein each of the back intermediate layers functions as a back side matching layer. The ultrasonic probe according to claim 1,
When the acoustic impedance of each piezoelectric element is Z1, the acoustic impedance of each back intermediate layer is Z2, and the acoustic impedance of the backing is Z3, the relationship of Z1>Z3> Z2 holds,
An ultrasonic probe, wherein each of the back intermediate layers functions as a back reflection layer. The ultrasonic probe according to claim 1,
Each of the back intermediate layers is formed of a conductive member,
An ultrasonic probe, wherein each of the back intermediate layers is also used as an electrode pad of each of the piezoelectric elements. A plurality of piezoelectric elements,
A backing provided on the back side of the plurality of piezoelectric elements and absorbing ultrasonic waves emitted from the plurality of piezoelectric elements to the back side,
A plurality of back intermediate layers functioning as electrode pads provided between each of the piezoelectric elements and the backing,
A plurality of leads electrically connected to the plurality of back intermediate layers,
An ultrasonic probe comprising: A step of bridging a plurality of conductive wires between the back intermediate member and the board,
Providing a backing between the back intermediate member and the substrate;
Providing a piezoelectric member on the upper surface side of the rear intermediate member;
Cutting the piezoelectric member and the rear intermediate member, thereby forming a plurality of piezoelectric elements and a plurality of rear intermediate layers,
A method for manufacturing an ultrasonic probe, comprising: The manufacturing method according to claim 7,
Between the step of providing the backing and the step of providing the piezoelectric member, including the step of providing an electrode member on the upper surface of the back intermediate layer,
The method for manufacturing an ultrasonic probe, wherein the plurality of piezoelectric elements, the plurality of electrode pads, and the plurality of back intermediate layers are formed by the cutting. The manufacturing method according to claim 8,
In the step of providing the backing, a liquid backing material is filled between the back intermediate member and the substrate, and is cured,
At this time, the method for manufacturing an ultrasonic probe, wherein the back intermediate member and the substrate function as positioning members for the plurality of conductive wires. The manufacturing method according to claim 9,
A plurality of through holes are previously formed in the back intermediate member,
The method of manufacturing an ultrasonic probe, wherein each of the conductive wires is inserted into each of the through holes.

Images