Ultrasound probe and method of manufacturing ultrasound probe

Provided are an ultrasound probe including high-sensitive piezoelectric elements and a method of manufacturing an ultrasound probe. The ultrasound probe includes a plurality of piezoelectric elements on a backing material arranged in an array along an arrangement direction. Each of the plurality of piezoelectric elements includes a laminate in which a first conductive part, a piezoelectric body part, and a second conductive part are laminated on a surface of the backing material in order. A plurality of acoustic matching part respectively arranged on the second conductive parts of the plurality of piezoelectric elements is provided. A plurality of third conductive parts acquired by respectively joining a part of the plurality of acoustic matching parts in an elevation direction to the second conductive parts of the plurality of piezoelectric elements is provided. A fourth conductive part that electrically connects the plurality of third conductive parts to each other is provided. The second conductive parts of the plurality of piezoelectric elements, the plurality of third conductive parts, and the fourth conductive part form a common electrode common to the plurality of piezoelectric elements.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an ultrasound probe and a method of manufacturing an ultrasound probe, and relates to an ultrasound probe including high-sensitive piezoelectric elements.

2. Description of the Related Art

In the related art, an ultrasound diagnostic apparatus using an ultrasound image has been put to practical use in the medical field. In general, this kind of ultrasound diagnostic apparatus generates an ultrasound image by transmitting an ultrasound beam toward a test subject from an ultrasound probe, receiving an ultrasound echo from the test subject by the ultrasound probe, and electrically processing received signals.

In the ultrasound diagnostic apparatus, since the generation of grating noise is suppressed, it has been known in the related art that an arrangement pitch between the piezoelectric elements of the ultrasound probe is decreased according to a wavelength of an ultrasound. In recent years, an ultrasound having a high frequency is transmitted and received in order to obtain a high-definition ultrasound image, and the wavelength of the ultrasound tends to be shortened. Accordingly, there is a need for a smaller arrangement pitch between the piezoelectric elements, that is, a narrower width of the piezoelectric elements. For example, JP1997-215095A (JP-H09-215095A) discloses an ultrasound probe including a plurality of piezoelectric elements arranged so as to have a narrow width in order to generate an ultrasound having a high frequency by driving the piezoelectric elements with a high driving frequency. In the ultrasound probe described in JP1997-215095A, the plurality of piezoelectric elements is formed on a backing material in an array, and acoustic matching parts are respectively arranged on the piezoelectric elements. Each of the plurality of piezoelectric elements includes a driving electrode part on a lower surface and a ground electrode part on an upper surface, and a common connection lead is connected to the ground electrode part.

SUMMARY OF THE INVENTION

At the time manufacturing the ultrasound probe described in JP1997-215095A, a driving electrode layer for forming the driving electrode part, a piezoelectric body layer made of a piezoelectric material, and a ground electrode layer for forming the ground electrode part which are formed as sheets are laminated on a surface of the backing material in order. A sheet-shaped acoustic matching layer for forming the acoustic matching parts is laminated on an upper surface of the ground electrode layer. At this time, a part of the upper surface of the ground electrode layer is exposed without being covered by the acoustic matching layer in order to be connected to the common connection lead. Subsequently, dicing for separating these layers at a predetermined pitch is performed. A portion of the upper surface of the ground electrode layer which is covered by the acoustic matching layer is protected from being damaged due to the dicing. However, the portion exposed without being covered by the acoustic matching layer is not protected from being damaged due to the dicing. Thus, the exposed portion of the ground electrode layer is broken, and thus, there is a concern that the sensitivity of the piezoelectric elements formed through the dicing will be degraded.

The invention has been made in order to solve the problem of the related art, and an object of the invention is to provide an ultrasound probe including high-sensitive piezoelectric elements and a method of manufacturing an ultrasound probe.

An ultrasound probe according to the invention is an ultrasound probe comprising a plurality of piezoelectric elements on a backing material arranged in an array along an arrangement direction. Each of the plurality of piezoelectric elements includes a laminate in which a first conductive part, a piezoelectric body part, and a second conductive part are laminated on a surface of the backing material in order. A plurality of acoustic matching parts respectively arranged on the second conductive parts of the plurality of piezoelectric elements is provided. A plurality of third conductive parts acquired by respectively joining a part of the plurality of acoustic matching parts in an elevation direction to the second conductive parts of the plurality of piezoelectric elements is provided. A fourth conductive part that electrically connects the plurality of third conductive parts to each other is provided. The second conductive parts of the plurality of piezoelectric elements, the plurality of third conductive parts, and the fourth conductive part form a common electrode common to the plurality of piezoelectric elements.

The plurality of third conductive parts and the fourth conductive part can form a commonization conductive part which spreads over the plurality of piezoelectric elements and has a single-layer structure in a lamination direction of the laminates.

In this case, the fourth conductive part can be constituted by a plurality of conductive fillers filling between the plurality of third conductive parts in the arrangement direction.

Alternatively, the fourth conductive part may extend in the arrangement direction over the plurality of piezoelectric elements, and may be joined to side surfaces of the plurality of third conductive parts in the elevation direction.

The plurality of third conductive parts and the fourth conductive part can form a commonization conductive part which spreads over the plurality of piezoelectric elements and has a structure in which a plurality of layers is laminated in the lamination direction of the laminates.

In this case, it is preferable that the fourth conductive part extends in the arrangement direction over the plurality of piezoelectric elements and is joined to surfaces of the plurality of third conductive parts in the lamination direction of the laminates.

Each of the plurality of third conductive parts may include a cut-out part cut such that a wall part protruding in the lamination direction of the laminates is formed at an end portion in the elevation direction, and the fourth conductive part may be arranged on the cut-out parts of the plurality of third conductive parts.

Alternatively, each of the plurality of third conductive parts may include a groove extending in the arrangement direction, and the fourth conductive part may be arranged within the grooves of the plurality of third conductive parts.

The fourth conductive part can have a lamination structure in which a plurality of layers is laminated in the lamination direction of the laminates.

In a case where the commonization conductive part having the structure of the plurality of layers is formed, the third conductive part has an acoustic impedance higher than an acoustic impedance of the fourth conductive part.

It is preferable that, in the lamination direction of the laminates, a thickness of the third conductive part has a value of substantially ¼ of a wavelength in a case where an ultrasound having a resonance frequency of the piezoelectric body part propagates through the third conductive part, and a thickness of the fourth conductive part has a value of substantially ¼ of a wavelength in a case where the ultrasound having the resonance frequency of the piezoelectric body part propagates through the fourth conductive part.

It is preferable that, in the lamination direction of the laminates, a thickness of the commonization conductive part has a value of substantially ¼ of an average wavelength in a case where an ultrasound having a resonance frequency of the piezoelectric body part propagates through the commonization conductive part.

The third conductive part can have a lamination structure in which a plurality of layers is laminated in the lamination direction of the laminates.

An insulation part can be further arranged on the commonization conductive part so as to correspond to the plurality of piezoelectric elements, and the insulation part can have an acoustic impedance lower than an acoustic impedance of the commonization conductive part.

In this case, it is preferable that, in the lamination direction of the laminates, each of a thickness of the commonization conductive part and a thickness of the insulation part has a value of substantially ¼ of an average wavelength in a case where an ultrasound having a resonance frequency of the piezoelectric body part propagates through the commonization conductive part.

Commonization conductive parts may be respectively arranged at both end portions of the second conductive part of each of the plurality of piezoelectric elements in the elevation direction.

It is preferable that the commonization conductive parts respectively arranged on both the end portions of the second conductive part of each of the plurality of piezoelectric elements in the elevation direction have sizes equal to each other and acoustic impedances equal to each other.

It is preferable that, in the lamination direction of the laminates, a thickness of the commonization conductive part and a thickness of a portion of the acoustic matching part other than the third conductive part have values which are substantially equal to each other.

A method of manufacturing an ultrasound probe according to the invention is a method of manufacturing an ultrasound probe including a plurality of piezoelectric elements on a backing material arranged in an array along an arrangement direction. The method comprising a first step of laminating a first conductive layer, a piezoelectric body layer, and a second conductive layer on a surface of the backing material in order; a second step of forming an acoustic matching layer and a third conductive layer which extend in the arrangement direction on a surface of the second conductive layer; a third step of forming a plurality of composite laminates separated from each other in the arrangement direction by dicing the first conductive layer, the piezoelectric body layer, the second conductive layer, the acoustic matching layer, and the third conductive layer at a set pitch along a direction crossing a direction in which the third conductive layer extends and in a lamination direction; and a fourth step of forming a fourth conductive part that electrically connects the third conductive layers of the plurality of composite laminates, which are separated from each other, to each other. A common electrode common to the plurality of piezoelectric elements is formed by using the second conductive layers and the third conductive layers of the plurality of composite laminates and the fourth conductive part.

The fourth conductive part can be formed by filling spaces between the third conductive layers of the plurality of composite laminates in the arrangement direction with conductive fillers.

Alternatively, the fourth conductive part may extend in the arrangement direction over the plurality of piezoelectric elements, and may be joined to the third conductive layers of the plurality of composite laminates.

The method of manufacturing an ultrasound probe may further comprise a step of filling spaces between the plurality of composite laminates with insulating fillers.

According to the invention, since the plurality of third conductive parts acquired by joining a part of the plurality of acoustic matching parts respectively arranged on the second conductive parts of the plurality of piezoelectric elements in the elevation direction to the second conductive parts of the plurality of piezoelectric elements is provided, the fourth conductive part that electrically connects the plurality of third conductive parts to each other is provided, and the plurality of third conductive parts and the fourth conductive part form the common electrode common to the plurality of piezoelectric elements, it is possible to realize the ultrasound probe including the high-sensitive piezoelectric elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A configuration of an ultrasound probe according to Embodiment 1 of the present invention is shown inFIGS. 1 and 2.

A plurality of piezoelectric elements2is arranged on a backing material1in an array at a predetermined pitch P1along an arrangement direction X, that is, an azimuth direction. The plurality of piezoelectric elements2extends in an elevation direction Y crossing the arrangement direction X.

Each piezoelectric element2has a piezoelectric body part21. A first conductive part22is joined to a surface of the piezoelectric body part21facing the backing material1, and a second conductive part23is joined to the other surface of the piezoelectric body part21. That is, each piezoelectric element2is constituted by a laminate in which the first conductive part22, the piezoelectric body part21, and the second conductive part23are laminated on a surface of the backing material1in order. The first conductive part22functions as a signal electrode of the piezoelectric element2. The second conductive part23functions as a ground electrode of the piezoelectric element2.

Acoustic matching parts3are joined to the second conductive parts23of the plurality of piezoelectric elements2, respectively. A main part31of the acoustic matching part3constitutes the most part of the acoustic matching part3. A portion of the acoustic matching part3other than the main part31includes a third conductive part32joined to the second conductive part23. The third conductive part32is arranged at an end portion of the acoustic matching part3in the elevation direction Y.

A gap is formed between the piezoelectric elements2adjacent to each other, and these piezoelectric elements2are separated from each other through this gap. A gap is also formed between the acoustic matching parts3adjacent to each other, and these acoustic matching parts3are separated from each other through this gap.

As shown inFIG. 3, insulating fillers4A fill the gaps between the piezoelectric elements2adjacent to each other, and thus, the positions of the plurality of piezoelectric elements2are fixed.

Insulating fillers4B also fill the gaps between the main parts31of the acoustic matching parts3adjacent to each other, and conductive fillers5fill gaps between the third conductive parts32of the acoustic matching parts3adjacent to each other. The plurality of insulating fillers4B and the plurality of conductive fillers5are provided, and thus, the positions of the plurality of acoustic matching parts3are fixed.

As shown inFIG. 4, each conductive filler5joins the third conductive parts32adjacent in the arrangement direction X to each other, and the plurality of conductive fillers5forms a fourth conductive part6which electrically connects the plurality of third conductive parts32to each other. That is, a commonization conductive part7which spreads over the plurality of piezoelectric elements2and has a single-layer structure in a lamination direction of the laminate constituting the piezoelectric element2is formed by the plurality of third conductive parts32and the fourth conductive part6, and a common electrode common to the plurality of piezoelectric elements2is formed by the second conductive parts23of the plurality of piezoelectric elements2and the commonization conductive part7. This common electrode causes the ground electrodes of the plurality of piezoelectric elements2, that is, the second conductive parts23to be electrically grounded in common.

The piezoelectric body part21of the piezoelectric element2is made of a known piezoelectric material. Examples of the piezoelectric material include piezo ceramics such as lead zirconate titanate (PZT) or polymer materials such as polyvinylidene fluoride (PVDF).

The backing material1supports the plurality of piezoelectric elements2and absorbs ultrasounds emitted backwards, and is made of a rubber material such as ferrite rubber.

Acoustic matching part3matches acoustic impedances of the piezoelectric body part21of the piezoelectric element2and a test subject used, and causes ultrasounds to be easily incident within the test subject. The main part31of the acoustic matching part3can be made of a material having an acoustic impedance which is lower than the acoustic impedance of the piezoelectric body part21and is higher than the acoustic impedance of the test subject. The main part31can be formed by laminating a plurality of layers made of such a material. For example, a layer made of a material having an acoustic impedance lower than an acoustic impedance of a layer arranged on the second conductive part23of the piezoelectric element2is laminated on the layer arranged on the second conductive part, and thus, a layer structure in which the acoustic impedances gradually decrease from the piezoelectric body part21to the test subject is formed.

Similarly to the main part31, the third conductive part32of the acoustic matching part3is made of a conductive material having an acoustic impedance which is lower than the acoustic impedance of the piezoelectric body part21and is higher than the acoustic impedance of the test subject.

The insulating fillers4A and4B are made of an insulating resin material or the like. Examples of the resin material include a silicone resin and an epoxy resin.

The plurality of conductive fillers5constituting the fourth conductive part6is made of a conductive material which has adhesiveness and conductivity to the third conductive part32. For example, the same material of the conductive material of the third conductive part32can be used as the conductive filler5.

Hereinafter, an operation of Embodiment 1 will be described.

The piezoelectric body parts21expand and contract by respectively applying pulsed or continuous wave voltages between the first conductive parts22of the plurality of piezoelectric elements2and the commonization conductive part7connected to the second conductive parts23of the plurality of piezoelectric elements2, and thus, pulsed or continuous wave ultrasounds are generated. In a case where these ultrasounds are incident within the test subject through the acoustic matching parts3, these ultrasounds are combined with each other, and thus, an ultrasound beam is formed. The ultrasound beam propagates within the test subject. In a case where ultrasound echoes which propagates and is reflected within the test subject are respectively incident on the piezoelectric body parts21through the acoustic matching parts3, the piezoelectric body parts21are deformed, and signal voltages are generated between the first conductive parts22and the second conductive parts23according to the deformation. The signal voltages generated in the plurality of piezoelectric elements2are extracted between the first conductive parts22of the piezoelectric elements2and the commonization conductive part7, and are received as reception signals. An ultrasound image is generated based on the reception signals.

In this example, since the common electrode has the structure in which the third conductive parts32of the acoustic matching parts3are joined to the second conductive parts23of the piezoelectric elements2, a cross-sectional area of the common electrode is larger than a cross-sectional area of the second conductive parts23. Accordingly, the common electrode has an electrical impedance lower than an electrical impedance of an electrode acquired by integrally connecting the plurality of second conductive parts23to each other along the arrangement direction X. Thus, even in a case where large voltages are applied between the first conductive parts22and the second conductive parts23or a plurality of piezoelectric elements2are simultaneously driven, it is possible to secure sufficient potential difference both at the time of transmission and at the time of reception between the first conductive part22and the second conductive part23, and it is possible to suppress reduction in Signal/Noise ratio (S/N ratio).

Such an ultrasound probe can be manufactured as follows.

Initially, a sheet-like first conductive layer122is joined to the surface of the backing material1by using an adhesive as shown inFIGS. 5 and 6. Subsequently, the first conductive layer122and a sheet-like piezoelectric body layer121are joined to each other by an adhesive, and the piezoelectric body layer121and a sheet-like second conductive layer123are joined by an adhesive. Accordingly, the first conductive layer122, the piezoelectric body layer121, and the second conductive layer123are laminated on the surface of the backing material1in order.

A sheet-like acoustic matching layer131extending in the arrangement direction X is joined by an adhesive so as to cover most of a surface of the second conductive layer123. A conductive paste acquired by dispersing conductive particles in an insulating material such as a resin is applied on the surface, of the entire surface of the second conductive layer123, which is not covered by the acoustic matching layer131, in a sheet extending in the arrangement direction X. For example, a third conductive layer132is formed by hardening the conductive paste through heating.

As shown inFIG. 7, the layers of the first conductive layer122, the piezoelectric body layer121, the second conductive layer123, the acoustic matching layer131, and the third conductive layer132are diced at the pitch P1along the elevation direction Y crossing the arrangement direction X so as to reach the backing material1in the lamination direction. It is preferable that the pitch P1becomes finer according to a driving frequency of the piezoelectric element2so as not to generate grating robes on the ultrasound image. For example, in a case where the driving frequency of the piezoelectric element2exceeds 15 MHz, it is preferable that the pitch P1is equal to or less than 150 μm, and it is more preferable that the layers are sub-diced at a pitch of 50 to 60 μm or less in order to optimize vibration efficiency of the piezoelectric element2. Since the second conductive layer123is covered by the acoustic matching layer131and the third conductive layer132at the time of dicing, the second conductive layer123is protected from being damaged due to the dicing. Accordingly, even in a case where the layers are diced at a small pitch P1, the second conductive layer123is effectively prevented from being broken.

Since the dicing is performed so as to reach the backing material1in the lamination direction, the layers of the first conductive layer122, the piezoelectric body layer121, the second conductive layer123, the acoustic matching layer131, and the third conductive layer132are separated from each other in the arrangement direction X through separation grooves8formed through the dicing. Accordingly, a plurality of composite laminates9arranged in an array at the pitch P1along the arrangement direction X is formed. The plurality of composite laminates9is configured such that the first conductive parts22, the piezoelectric body parts21, and the second conductive parts23are laminated in order and the main parts31and the third conductive parts32of the acoustic matching parts3are arranged on the second conductive parts23so as to be line up in the elevation direction Y.

Subsequently, the insulating fillers4A fill gaps between the composite laminates9adjacent to each other, that is, the separation grooves8, as shown inFIG. 8. At this time, the insulating filler4A fills the space from a lower end of the composite laminate9in the lamination direction, that is, the surface of the backing material1to an upper end of the piezoelectric element2constituted by the first conductive part22, the piezoelectric body part21, and the second conductive part23.

Thereafter, within the separation groove8, the insulating filler4B fills the space which is between the main parts31of the acoustic matching parts3adjacent each other and is on the insulating filler4A, and the conductive filler5fills the space which is between the third conductive parts32of the acoustic matching parts3adjacent to each other and is on the insulating filler4A.

A conductive paste can be used as the conductive filler5. The fourth conductive part6that electrically connects the plurality of third conductive parts32to each other is formed by filling the separation grooves8with a conductive paste and hardening the conductive paste through heating. The commonization conductive part7spreading over the plurality of piezoelectric elements2is formed by forming the fourth conductive part6, and the ultrasound probe having the structure shown inFIGS. 1 and 2is manufactured.

Since the plurality of piezoelectric elements2of the ultrasound probe manufactured in this manner is protected from being damaged due to the dicing, the piezoelectric elements are broken or performance is deteriorated, and thus, sensitivity is prevented from being degraded. It is possible to easily form the common electrode common to the plurality of piezoelectric elements2by using the fourth conductive part6that electrically connects the second conductive parts23of the plurality of piezoelectric elements2to each other, the third conductive parts32of the plurality of acoustic matching parts3, and the plurality of third conductive parts32to each other.

In contrast, in a method of manufacturing an ultrasound probe in the related art, a driving electrode layer, a piezoelectric body layer, a ground electrode layer, and an acoustic matching layer which are respectively formed as sheets are laminated on a surface of a backing material in order. However, a part of a surface of the ground electrode layer is exposed without being covered by the acoustic matching layer in order to connect a common electrode to the ground electrode layer. A portion of the surface of the ground electrode layer which is not covered by the acoustic matching layer is protected from being damaged due to the dicing at the time of dicing these layers. However, the portion exposed without being covered by the acoustic matching layer is not protected from being damaged due to the dicing. Thus, the exposed portion of the ground electrode layer is broken, and thus, there is a concern that the sensitivity of the piezoelectric elements formed through the dicing will be degraded.

It is preferable that, in the lamination direction of the laminates constituting the piezoelectric element2, a thickness of the commonization conductive part7having a single-layer structure, that is, a thickness of the third conductive part32has a value of substantially ¼ of an average wavelength in a case where an ultrasound having a resonance frequency of the piezoelectric body part21propagates through the third conductive part32in order to satisfy a resonance condition.

It is preferable that the thickness of the commonization conductive part7having the single-layer structure, that is, the thickness of the third conductive part32of the acoustic matching part3and a thickness of the main part31of the acoustic matching part3have values which are substantially equal to each other in order for all the acoustic matching parts3to easily satisfy the resonance condition.

As shown inFIGS. 9 and 10, an insulation part10formed so as to extend in the arrangement direction X over the plurality of piezoelectric elements2can be arranged on the third conductive parts32. The insulation part10is made of an insulating material having an acoustic impedance which is lower than the acoustic impedance of the third conductive part32and is higher than the acoustic impedance of the test subject. Accordingly, it is preferable that the insulation part is made of such an insulating material in order to form a layer structure in which the acoustic impedances gradually decrease from the piezoelectric element2to the test subject. The insulation part10protects upper surfaces of the third conductive parts32by electrically insulating the upper surface thereof. The insulation part10may be arranged while being divided into a plurality of parts so as to respectively correspond to the plurality of piezoelectric elements2instead of extending in the arrangement direction X over the plurality of piezoelectric elements2. The insulation part10can be made of an epoxy resin or the like.

It is preferable that, in the lamination direction of the laminates constituting the piezoelectric element2, the thickness of the third conductive part32and the thickness of the insulation part10have a value of substantially ¼ of an average wavelength in a case where an ultrasound having a resonance frequency of the piezoelectric body part21propagates through the third conductive part32in order for the third conductive part32and the insulation part10to satisfy the resonance condition.

As shown inFIGS. 11 and 12, the third conductive parts32of the acoustic matching part3can be respectively arranged on upper surfaces of both end portions of the second conductive part23of the piezoelectric element2in the elevation direction Y, and the commonization conductive parts7can be formed on both end portions of the piezoelectric element2in the elevation direction Y. Accordingly, it is preferable that the upper surfaces of both the end portions of the second conductive part23in the elevation direction Y are respectively covered by the third conductive parts32in order to improve impact resistance of the plurality of piezoelectric elements2. As shown inFIGS. 9 and 10, the insulation parts10may be arranged on both the third conductive parts32.

Since the third conductive parts32are respectively arranged on both sides of the main part31of the acoustic matching part3in the elevation direction Y, the main part31and both the third conductive parts32can be configured such that transmission sound pressure and reception sound pressure at both the third conductive parts32are lower than those at the main part31. Accordingly, the ultrasound beam is focused in the elevation direction Y, and a width of the ultrasound beam in the elevation direction Y is narrowed. Thus, resolution is improved, and thus, it is possible to generate an ultrasound image having higher definition. At this time, both the third conductive parts32have the sizes equal to each other, and have the acoustic impedances equal to each other. Accordingly, it is possible to focus the ultrasound beam with higher accuracy in the elevation direction Y.

A configuration of an ultrasound probe according to Embodiment 2 are shown inFIGS. 13 and 14. This ultrasound probe is different from the ultrasound probe of Embodiment 1 shown inFIGS. 1 and 2in that the plurality of third conductive parts32are electrically connected to each other by joining a fourth conductive part11extending in the arrangement direction X over the plurality of piezoelectric elements2to side surfaces of the plurality of third conductive parts32in the elevation direction instead of filling the gaps between the third conductive parts32of the acoustic matching parts3adjacent to each other with the conductive fillers5. A commonization conductive part12which is over the plurality of piezoelectric elements2and has a single-layer structure in the lamination direction of the laminates constituting the piezoelectric element2is formed by the plurality of third conductive parts32and the fourth conductive part11. A common electrode common to the plurality of piezoelectric elements2is formed by the second conductive parts23of the plurality of piezoelectric elements2and the commonization conductive part12.

As shown inFIG. 15, the insulating fillers4A fill between the piezoelectric elements2adjacent to each other and between the acoustic matching parts3adjacent to each other, and thus, the positions of the plurality of piezoelectric elements2and the positions of the plurality of acoustic matching parts3are fixed.

Similarly to the ultrasound probe of Embodiment 1, the ultrasound probe of Embodiment 2 can be manufactured in a such a manner that the plurality of composite laminates9arranged in an array along the arrangement direction X is formed by dicing the layers in a state in which the second conductive layer123is covered by the acoustic matching layer131and the third conductive layer132as shown inFIGS. 5 to 7, the insulating fillers4A fill the gaps between the composite laminates9adjacent to each other, and the fourth conductive part11extending in the arrangement direction X over the plurality of piezoelectric elements2is joined to the side surfaces of the plurality of third conductive parts32in the elevation direction.

Accordingly, the plurality of piezoelectric elements2is protected from being damaged due to the dicing, and thus, it is possible to prevent the sensitivity from being degraded even though the pitch P1between the piezoelectric elements2is small.

For example, the fourth conductive part11can be formed by applying the conductive paste in a strip shape which spreads over the plurality of piezoelectric elements2and extends in the arrangement direction X to the side surfaces of the plurality of third conductive parts32in the elevation direction and hardening the conductive paste through heating.

It is preferable that, in the lamination direction of the laminates constituting the piezoelectric element2, a thickness of the commonization conductive part12having a single-layer structure, that is, the thickness of the third conductive part32has a value of substantially ¼ of an average wavelength in a case where an ultrasound having a resonance frequency of the piezoelectric body part21propagates through the third conductive part32in order to satisfy the resonance condition.

It is preferable that the thickness of the commonization conductive part12having the single-layer structure, that is, the thickness of the third conductive part32of the acoustic matching part3and the thickness of the main part31of the acoustic matching part3have values which are substantially equal to each other in order for all the acoustic matching parts3to easily satisfy the resonance condition.

Similarly to the ultrasound probe shown inFIGS. 9 and 10, in Embodiment 2, the insulation part10can be arranged on the third conductive parts32, and thus, a layer structure in which the acoustic impedances gradually decrease from the piezoelectric element2to the test subject.

Similarly to the ultrasound probe shown inFIGS. 11 and 12, the third conductive parts32of the acoustic matching part3are respectively arranged on upper surfaces of both end portions of the second conductive part23of the piezoelectric element2in the elevation direction Y, and the commonization conductive parts12having the single-layer structure can be formed on both the end portions of the piezoelectric element2in the elevation direction Y. Accordingly, the upper surfaces of both the end portions of the second conductive part23in the elevation direction Y are covered by the third conductive parts32, and the impact resistance of the plurality of piezoelectric elements2is improved. The main part31and both the third conductive parts32can be configured such that transmission sound pressure and reception sound pressure at both the third conductive parts32are lower than those at the main part31of the acoustic matching part3, and thus, the ultrasound beam is focused in the elevation direction Y. Accordingly, it is possible to generate an ultrasound image having higher definition. At this time, both the third conductive parts32have the sizes equal to each other, and have the acoustic impedances equal to each other. Accordingly, it is possible to focus the ultrasound beam with higher accuracy in the elevation direction Y.

A configuration of an ultrasound probe according to Embodiment 3 are shown inFIGS. 16 and 17. This ultrasound probe is different from the ultrasound probe of Embodiment 2 shown inFIGS. 13 and 14in that the plurality of third conductive parts32is electrically connected to each other by joining a fourth conductive part13which spreads over the plurality of piezoelectric elements2and extends in the arrangement direction X to upper surfaces of the plurality of third conductive parts32, that is, surfaces of the plurality of third conductive parts32in the lamination direction of the laminates constituting the piezoelectric element2instead of joining the fourth conductive part11to the side surfaces of the plurality of third conductive parts32in the elevation direction.

As shown inFIG. 18, a commonization conductive part14which spreads over the plurality of piezoelectric elements2and has a structure in which two layers are laminated in the lamination direction of the laminates constituting the piezoelectric element2is formed by the plurality of third conductive parts32and the fourth conductive part13. The common electrode common to the plurality of piezoelectric elements2is formed by the second conductive parts23of the plurality of piezoelectric elements2and the commonization conductive part14.

Similarly to the ultrasound probe of Embodiment 1, the ultrasound probe of Embodiment 3 can be manufactured as shown inFIG. 17in such a manner that the plurality of composite laminates9arranged in an array along the arrangement direction X is formed by dicing the layers in a state in which the second conductive layer123is covered by the acoustic matching layer131and the third conductive layer132as shown inFIGS. 5 to 7, the insulating fillers4A fill the gaps between the composite laminates9adjacent to each other as shown inFIGS. 19 and 20, and the fourth conductive part13extending in the arrangement direction X over the plurality of piezoelectric elements2is joined to the upper surfaces of the plurality of third conductive parts32.

Accordingly, the plurality of piezoelectric elements2is protected from being damaged due to the dicing, and thus, it is possible to prevent the sensitivity from being degraded even though the pitch P1between the piezoelectric elements2is small.

The fourth conductive part13can be formed by applying a conductive paste acquired by dispersing conductive particles in an insulating material such as a resin on the upper surfaces of the plurality of third conductive parts32and hardening the conductive paste through heating.

It is preferable that the fourth conductive part13arranged on the upper surfaces of the plurality of third conductive parts32has an acoustic impedance which is lower than the acoustic impedance of the third conductive part32and is higher than the acoustic impedance of the test subject.

It is preferable that, in the lamination direction of the laminates constituting the piezoelectric element2, the thickness of the third conductive part32has a value of substantially ¼ of the average wavelength in a case where an ultrasound having a resonance frequency of the piezoelectric body part21propagates through the third conductive part32and the thickness of the fourth conductive part13has a value of substantially ¼ of an average wavelength in a case where the ultrasound having the resonance frequency of the piezoelectric body part21propagates through the third conductive part32in order to satisfy the resonance condition.

It is preferable that the entire thickness of the commonization conductive part14having the two-layer structure has a value of substantially ¼ of an average wavelength in a case where the ultrasound having the resonance frequency of the piezoelectric body part21propagates through the commonization conductive part14in order to satisfy the resonance condition.

It is preferable that the entire thickness of the commonization conductive part14having the two-layer structure and the thickness of the main part31of the acoustic matching part3have values which are substantially equal to each other in order for all the acoustic matching parts3to easily satisfy the resonance condition.

As shown inFIG. 21, the insulation part10can be arranged on the fourth conductive part13. In a case where the insulation part10is made of an insulating material having an acoustic impedance which is lower than the acoustic impedance of the fourth conductive part13and is higher than the acoustic impedance of the test subject, a layer structure in which the acoustic impedances gradually decrease from the piezoelectric element2to the test subject can be formed.

For example, the third conductive part32can be made of a high-concentration Ag (silver) paste having an acoustic impedance of 14.8 Mrayl, the fourth conductive part13can be made of a relatively-low-concentration Ag paste having an acoustic impedance of 4.25 Mrayl, and the insulation part10can be made of a resin material such as an epoxy resin having an acoustic impedance of 1.85 Mrayl. 1 Mrayl=106kg·m−2·s−1. The fourth conductive part13can be made of a conductive paste acquired by dispersing Cu (copper), Fe (iron), Ni (nickel), Al (aluminum), C (carbon) particles having a density lower than a density of the Ag in an insulating material.

The third conductive part32can be constituted by a plurality of conductive layers laminated in the lamination direction of the laminates constituting the piezoelectric element2. For example, in the ultrasound probe shown inFIG. 22, the third conductive part32has a lamination structure in which two layers including a first layer321joined to the upper surface of the second conductive part23of the piezoelectric element2and a second layer322joined to the upper surface of the first layer321are laminated. The third conductive part32has the lamination structure in which the plurality of layers is laminated in this manner, and thus, a layer structure in which the acoustic impedances smoothly decrease from the piezoelectric element2to the test subject is formed. Accordingly, it is possible to transmit and receive the ultrasound with higher efficiency.

For example, the first layer321of the third conductive part32can be made of a high-density medium paste having an acoustic impedance of 20.6 Mrayl, the second layer322of the third conductive part32can be made of a high-concentration Ag paste having an acoustic impedance of 7.51 Mrayl, the fourth conductive part13can be made of a relatively-low-concentration Ag paste having an acoustic impedance of 2.74 Mrayl, and the insulation part10can be made of a resin material such as an epoxy resin having an acoustic impedance of 1.66 Mrayl.

A conductive paste acquired by dispersing noble particles such as Au or Pt (platinum) in an insulating material such as a resin can be used as the high-density medium paste which is the material for forming the first layer321of the third conductive part32. The fourth conductive part13can be made of a conductive paste acquired by dispersing Cu, Fe, Ni, Al, or C particles having a density lower than the density of the Ag in an insulating material such as a resin.

Similarly, a layer structure in which the acoustic impedances smoothly decrease even though the third conductive part32is constituted by the single layer and the fourth conductive part13is constituted by the plurality of layers. For example, the third conductive part32can be made of a high-density medium paste having an acoustic impedance of 20.6 Mrayl, the fourth conductive part13can have a lamination structure in which two layers including a first layer which is joined to the third conductive part32and is made of a high-concentration Ag paste having an acoustic impedance of 7.51 Mrayl and a second layer which is joined to the first layer and is made of a relatively-low-concentration Ag paste having an acoustic impedance of 2.74 Mrayl, and the insulation part10can be made of a resin material such as an epoxy resin having an acoustic impedance of 1.66 Mrayl.

Similarly, the fourth conductive part13having a lamination structure of a plurality of layers can be formed on the third conductive part32having a lamination structure of a plurality of layers.

Similarly to the ultrasound probe shown inFIGS. 11 and 12, the third conductive parts32of the acoustic matching part3can be respectively arranged on the upper surfaces of both the end portions of the second conductive part23of the piezoelectric element2in the elevation direction Y, and the commonization conductive parts14having the two-layer structure can be respectively formed on both the end portions of the piezoelectric element2in the elevation direction Y. Accordingly, the upper surfaces of both the end portions of the second conductive part23in the elevation direction Y are covered by the commonization conductive part14, and the impact resistance of the plurality of piezoelectric elements2is improved. The main part31and both the commonization conductive parts14can be configured such that transmission sound pressure and reception sound pressure at both the commonization conductive parts14are lower than those at the main part31of the acoustic matching part3, and thus, the ultrasound beam is focused in the elevation direction Y. Accordingly, it is possible to generate an ultrasound image having higher definition. At this time, the commonization conductive parts14at both the end portions in the elevation direction Y have the sizes equal to each other, and have the acoustic impedances equal to each other. Accordingly, it is possible to focus the ultrasound beam in the elevation direction Y with higher accuracy.

A configuration of an ultrasound probe according to Embodiment 4 are shown inFIGS. 23 and 24. This ultrasound probe is different from the ultrasound probe of Embodiment 3 shown inFIGS. 16 and 17in that each of the plurality of third conductive parts32has a cut-out part32A extending in the arrangement direction X and the plurality of third conductive parts32is electrically connected to each other by joining the fourth conductive part13extending in the arrangement direction X over the plurality of piezoelectric elements2on the cut-out parts32A of the plurality of third conductive parts32.

The cut-out part32A is cut such that a wall part32B protruding in the lamination direction of the laminates constituting the piezoelectric element2is formed at an end portion of the third conductive part32in the elevation direction Y.

As stated above, even though the fourth conductive part13is arranged on the cut-out parts32A formed on the plurality of third conductive parts32, the commonization conductive part14which spreads over the plurality of piezoelectric elements2and has a structure in which two layers are laminated in the lamination direction of the laminates constituting the piezoelectric element2is formed by the plurality of third conductive parts32and the fourth conductive part13, and the common electrode common to the plurality of piezoelectric elements2is formed by the second conductive parts23of the plurality of piezoelectric elements2and the commonization conductive part14.

Similarly to the ultrasound probe of Embodiment 1, the ultrasound probe of Embodiment 4 can be manufactured as shown inFIG. 24in such a manner that the plurality of composite laminates9arranged in an array along the arrangement direction X is formed by dicing the layers in a state in which the second conductive layer123is covered by the acoustic matching layer131and the third conductive layer132as shown inFIGS. 5 to 7, the insulating fillers4A fill the gaps between the composite laminates9adjacent to each other as shown inFIGS. 25 and 26, the cut-out parts32A extending in the arrangement direction X are formed in the upper surfaces of the plurality of third conductive parts32, the wall part32B is formed at the end portion of each of the third conductive parts32in the elevation direction Y, and the fourth conductive part13extending in the arrangement direction X over the plurality of piezoelectric elements2is joined to the cut-out parts32A of the plurality of third conductive parts32.

Accordingly, the plurality of piezoelectric elements2is protected from being damaged due to the dicing, and thus, it is possible to prevent the sensitivity from being degraded even though the pitch P1between the piezoelectric elements2is small.

The cut-out parts32A of the plurality of third conductive parts32can be formed by cutting the upper surfaces of the plurality of third conductive parts32in the arrangement direction X multiple number of times by using a cutting tool (not shown) having a set width. At this time, since the insulating fillers4A fills the gaps between the composite laminates9adjacent to each other, a cut-out part and a wall part at the end portion in the elevation direction Y are formed at the insulating filler4A, the cut-out parts32A of the third conductive parts32and the cut-out parts of the insulating fillers4A extend in the arrangement direction X, and the wall parts32B of the third conductive parts32and the wall parts of the insulating fillers4A extend in the arrangement direction X.

Thus, even though the conductive paste is applied to the cut-out part32A of the third conductive part32and the cut-out part of the insulating filler4A at the time of forming the fourth conductive part13, the conductive paste is prevent from being dropped toward the piezoelectric element2from the end portion in the elevation direction Y by the wall parts32B of the third conductive parts32and the wall parts of the insulating fillers4A extending in the arrangement direction X. Accordingly, the common electrode can be prevented from short-circuiting the first conductive part22of the piezoelectric element2due to the liquid dropping of the conductive paste.

Since the cut-out parts32A are formed on the upper surfaces of the plurality of third conductive parts32, even though the upper surfaces of the third conductive parts32are deteriorated or contaminants adhere to the upper surfaces of the third conductive parts32, these deteriorated portions and contaminants are removed at the time of forming the cut-out parts32A, and the surfaces of the cut-out parts32A are activated. Thus, electrical connectivity and joining ability of the fourth conductive part13to the third conductive parts32are improved, and thus, a high-reliability ultrasound probe is realized.

Similarly to Embodiment 3, one of the third conductive part32and the fourth conductive part13or both the third conductive part32and the fourth conductive part13can also have the lamination structure in which the plurality of layers is laminated in Embodiment 4.

Similarly to the ultrasound probe shown inFIGS. 9 and 10, the insulation part10can be arranged on the fourth conductive part13.

Similarly to the ultrasound probe shown inFIGS. 11 and 12, the third conductive parts32of the acoustic matching part3can be respectively arranged on the upper surfaces of both the end portions of the second conductive part23of the piezoelectric element2in the elevation direction Y, and the commonization conductive parts14having the two-layer structure can be respectively formed at both the end portions of the piezoelectric element2in the elevation direction Y.

A configuration of an ultrasound probe according to Embodiment 5 are shown inFIGS. 27 and 28. This ultrasound probe is different from the ultrasound probe of Embodiment 3 shown inFIGS. 16 and 17in that grooves32C extending in the arrangement direction X are respectively formed in the plurality of third conductive parts32and the plurality of third conductive parts32are electrically connected to each other by joining the fourth conductive part13extending in the arrangement direction X over the plurality of piezoelectric elements2to the grooves32C of the plurality of third conductive parts32.

As stated above, even though the fourth conductive part13is arranged within the grooves32C formed in the plurality of third conductive parts32, the commonization conductive part14which spreads over the plurality of piezoelectric elements2and has the structure in which the two layers are laminated in the lamination direction of the laminates constituting the piezoelectric element2is formed by the plurality of third conductive parts32and the fourth conductive part13, and the common electrode common to the plurality of piezoelectric elements2is formed by the second conductive parts23of the plurality of piezoelectric elements2and the commonization conductive part14.

Similarly to the ultrasound probe of Embodiment 1, the ultrasound probe of Embodiment 5 can be manufactured in such a manner that the plurality of composite laminates9arranged in an array along the arrangement direction X is formed by dicing the layers in a state in which the second conductive layer123is covered by the acoustic matching layer131and the third conductive layer132as shown inFIGS. 5 to 7, the insulating fillers4A fill the gaps between the composite laminates9adjacent to each other as shown inFIGS. 29 and 30, the grooves32C extending in the arrangement direction X are formed in the upper surfaces of the plurality of third conductive parts32, and the fourth conductive part13extending in the arrangement direction X over the plurality of piezoelectric elements2is joined within the grooves32C of the plurality of third conductive parts32.

Accordingly, the plurality of piezoelectric elements2is protected from being damaged due to the dicing, and thus, it is possible to prevent the sensitivity from being degraded even though the pitch P1between the piezoelectric elements2is small.

The grooves32C of the plurality of third conductive parts32can be formed by cutting the upper surfaces of the plurality of third conductive parts32in the arrangement direction X at least one time by using a cutting tool (not shown) having a set width. Thus, it is possible to easily manufacture the ultrasound probe with a smaller number of steps as compared to Embodiment 4 in which the cut-out parts32A are formed in the upper surfaces of the plurality of third conductive parts32.

Grooves are also formed in the insulating fillers4A filling the gaps between the composite laminates9adjacent to each other at the time of forming the grooves32C, and the grooves32C of the third conductive parts32and the grooves of the insulating fillers4A extend in the arrangement direction X.

Thus, even though the conductive paste is applied to the grooves32C of the third conductive parts32and the grooves of the insulating fillers4A at the time of forming the fourth conductive part13, the conductive paste is prevented from being dropped toward the piezoelectric element2from the end portion in the elevation direction Y. Accordingly, the common electrode can be prevented from short-circuiting the first conductive part22of the piezoelectric element2due to the liquid dropping of the conductive paste.

Since the grooves32C are formed in the upper surfaces of the plurality of third conductive parts32, even though the upper surfaces of the third conductive parts32are deteriorated or contaminants adhere to the upper surfaces of the third conductive parts32, these deteriorated portions and the contaminants are removed at the time of forming the grooves32C, and the inner wall surfaces of the grooves32C are activated. Thus, electrical connectivity and joining ability of the fourth conductive part13to the third conductive parts32are improved, and thus, a high-reliability ultrasound probe is realized.

Similarly to Embodiment 3, one of the third conductive part32and the fourth conductive part13or both the third conductive part32and the fourth conductive part13can also have the lamination structure in which the plurality of layers is laminated in Embodiment 5.

Similarly to the ultrasound probe shown inFIGS. 9 and 10, the insulation part10can be arranged on the fourth conductive part13.

Similarly to the ultrasound probe shown inFIGS. 11 and 12, the third conductive parts32of the acoustic matching part3can be respectively arranged on the upper surfaces of both the end portions of the second conductive part23of the piezoelectric element2in the elevation direction Y, and the commonization conductive parts14having the two-layer structure can be respectively formed at both the end portions of the piezoelectric element2in the elevation direction Y.

Although it has been described in Embodiments 1 to 5 described above that the conductive paste acquired by dispersing the conductive particles in the insulating material is used for forming the third conductive parts32and the fourth conductive parts6,11, and13, particles having various shapes such as a spherical shape, a flake shape (thin piece shape), and a dendrite shape having a plurality of protrusions can be used as the conductive particles. Au, Pt, Ag, Cu, Fe—Pt, C (including carbon and graphite), Ni, or Al can be used as the material of the conductive particles.

Low-melting-point glass can be used as the insulating material for dispersing the conductive particles in addition to resin materials such as an epoxy resin, a urethane resin, an acrylic resin, a silicone resin, and a polyimide resin.

The third conductive parts32and the fourth conductive parts11and13other than the fourth conductive part6constituted by the plurality of conductive fillers5can be formed by using the conductive material such as Au, Pt, Ag, Ti (titanium), Cu, Cr (chromium), C, Ni, or Al by a sputter deposition method, a thermal evaporation method, an electrolytic plating method, an electroless plating method, or a baking method instead of applying and hardening the conductive paste.

A conductive sheet including a rod-shaped conductor can be used as the material for forming the third conductive parts32and the fourth conductive parts11and13.

EXPLANATION OF REFERENCES