Ultrasonic array transducer, associated circuit and methods of making the same

In some embodiments, circuits for ultrasonic transducer element arrays are provided. In some embodiments, a circuit described herein comprises a first layer for receiving a transducer element array, a ground layer comprising at least one ground disposed over the first layer and a plurality of first vias corresponding to transducer elements of the array, the first vias extending through the first layer to the at least one ground and comprising first ends for receiving ground electrodes of the transducer elements and second ends electrically connected to the ground.

FIELD

Embodiments relate in general to transducers and, more particularly, to ultrasonic array transducers.

BACKGROUND

There are a number of ways in which an ultrasonic transducer can be made. One manufacturing approach will be described in connection withFIG. 1. A monolithic block of piezoelectric ceramic material10is provided. A portion of the piezoelectric material10is covered by a plating material12wrapped therearound. Deactivation cuts14are made along a top surface of the plating material12to define a positive electrode16and a ground electrode18. The deactivation cuts14extend into and out of the page inFIG. 1. The positive electrode16is formed by that portion of the plating material12located between the two deactivation cuts14. The ground electrode18is formed by the plating material12outside of the two deactivation cuts14. With the use of a wrap around plating material12, electrical connections to the positive and ground electrodes16,18can be easily made on the same surface of the piezoelectric material10. The block of piezoelectric ceramic material10and the plating material12with the deactivation cuts14form a piezoelectric material/electrode assembly24.

A flexible circuit22is disposed on the top of the piezoelectric material/electrode assembly24. Electrical connections are made between individual traces of the flexible circuit22and the positive and ground electrodes16,18in locations of each intended transducer element. For instance, wires can be soldered onto the positive and ground electrodes16,18and attached to individual traces of the flexible circuit22. A solid backer26is bonded to the top side of the piezoelectric material/electrode assembly24with the flexible circuit22sandwiched therebetween. One or more matching layers28are then attached to the bottom side of the piezoelectric material/electrode assembly24.

A plurality of individual transducer elements are formed using a dicing saw30to make a plurality of parallel dices or cuts in the assembly. The dicing saw30is brought into contact with the assembly from the patient side of the assembly, that is, from the matching layer28side of the assembly. Thus, the dicing saw30cuts through the one or more matching layers28, through the plating material12, through the piezoelectric material10, through the flexible circuit22and into a portion of the backer26. A plurality of transducer elements are developed by the dicing operation. The cuts formed by the dicing saw30can extend in a direction that is perpendicular to the direction in which the deactivation cuts14extend.

The undiced portion of the backer26holds the diced assembly together. After the dicing operation, kerf filler can be placed in the cuts to provide structural support to the diced assembly. The kerf filler can also provide some degree of acoustic isolation between the transducer elements.

However, when dices are made in the assembly, the common ground electrode18is severed, and a plurality of individual ground electrodes is formed. The individual ground electrodes must be reconnected. Typically, a wire is soldered across the individual ground electrodes to reconnect the ground electrodes. This process is labor intensive and time consuming. Further, the heat from the soldering process can depolarize the piezoelectric material10, thereby adversely affecting the performance of the transducer.

SUMMARY

In one aspect, circuits for transducer element arrays are described herein which, in some embodiments, may assist in mitigating one or more disadvantages associated with individual ground electrode reconnection. In some embodiments, circuits described herein are flexible circuits. In some embodiments, a circuit described herein comprises a first layer for receiving a transducer element array, a ground layer comprising at least one ground disposed over the first layer and a plurality of first vias corresponding to transducer elements of the array, the first vias extending through the first layer to the at least one ground and comprising first ends for receiving ground electrodes of the transducer elements and second ends electrically connected to the ground.

In some embodiments, the ground layer comprises a plurality of grounds for interfacing with ground electrodes of transducer elements through the first vias. In being disposed over the first layer, the ground layer, in some embodiments, is adjacent to the first layer. Alternatively, in some embodiments, one or more additional layers are disposed between the first layer and the ground layer. In some embodiments wherein one or more additional layers are disposed between the first layer and the ground layer, the first vias extend through the first layer and the one or more additional layers to the ground(s) of the ground layer.

Moreover, in some embodiments, a circuit described further herein comprises one or more ground vias for electrically connecting one or more grounds of the ground layer to an external circuit, such as that of an ultrasound system. In some embodiments, a ground via extends through the ground layer to the exterior of the circuit. In some embodiments, for example, a ground via extends laterally out of the ground layer. In some embodiments, a ground via extends into one or more layers adjacent to the ground layer.

A circuit described herein, in some embodiments, further comprises second vias corresponding to transducer elements of the array, the second vias extending through the first layer and comprising first ends for receiving positive electrodes of the transducer elements and second ends electrically connected to traces in electrical communication with circuitry external to the circuit, such as that of an ultrasound system. In some embodiments, at least some of the second vias terminate in one or more additional layers disposed between the first layer and the ground layer. In some embodiments, at least some of the second vias terminate in one or more additional layers disposed over the ground layer. In some embodiments, at least some of the second vias terminate in the ground layer. In some embodiments, a first number of second vias terminate in a different layer of the circuit than a second number of second vias.

In another aspect, ultrasonic transducer systems are described herein. In some embodiments, an ultrasonic transducer system comprises an array comprising a plurality of transducer elements, the transducer elements comprising individual positive electrodes and ground electrodes and a circuit coupled to the array, the circuit comprising a first layer for receiving the array, a ground layer comprising at least one ground disposed over the first layer and a plurality of first vias corresponding to transducer elements of the array, the first vias extending through the first layer to the at least one ground and comprising first ends electrically connected to individual ground electrodes of the transducer elements and second ends electrically connected to the ground of the ground layer.

In some embodiments, a circuit of an ultrasonic transducer system described herein further comprises one or more ground vias for electrically connecting one or more grounds of the ground layer to an external circuit, such as that of an ultrasound system. In some embodiments, a ground via extends through the ground layer to the exterior of the circuit. In some embodiments, for example, a ground via extends laterally out of the ground layer. Moreover, in some embodiments, a ground via extends into one or more layers adjacent to the ground layer.

A circuit of an ultrasonic transducer system, in some embodiments, further comprises second vias corresponding to transducer elements of the array, the second vias extending through the first layer and comprising first ends electrically connected to positive electrodes of the transducer elements and second ends electrically connected to one or more traces in electrical communication with an ultrasound system. In some embodiments, at least one second via is associated with a positive electrode of each transducer element of the array.

In some embodiments, at least some of the second vias terminate in one or more additional layers disposed between the first layer and the ground layer of the circuit. In some embodiments, at least some of the second vias terminate in one or more additional layers disposed over the ground layer. In some embodiments, at least some of the second vias terminate in the ground layer. In some embodiments, a first number of second vias terminate in a different layer of the circuit than a second number of second vias.

As illustrated in the Figures of the present application, an ultrasonic transducer system described herein can have an associated axial direction A, a longitudinal direction L that is transverse to the axial direction A, and a thickness direction T. In some embodiments, a transducer element array of an ultrasonic transducer system described herein comprises a piezoelectric material separated into N transducer elements in the axial direction to provide an N×1 array. In some embodiments, a transducer element array of an ultrasonic transducer system comprises a piezoelectric material separated into N transducer groups in the axial direction and M transducer elements in the longitudinal direction transverse to the axial direction to provide an N×M array. In some embodiments, a transducer element array of an ultrasonic transducer system described herein is a curved array. In some embodiments, a transducer element array of an ultrasonic transducer system described herein is a planar array.

In another aspect, methods of making transducer assemblies are described herein. In some embodiments, a method of making a transducer assembly comprises providing a piezoelectric element partially covered with a plating material defining a ground electrode and at least one positive electrode and providing a circuit comprising a first layer for receiving the piezoelectric element, a ground layer comprising at least one ground disposed over the first layer and a plurality of first vias extending through the first layer to the at least one ground and comprising first ends for receiving the ground electrode of the piezoelectric element and second ends electrically connected to the at least one ground. The first layer of the circuit is interfaced with the piezoelectric element and the first ends of the first vias are placed in electrical communication with the ground electrode of the piezoelectric element. A plurality of cuts are made in the piezoelectric element having a depth passing through the piezoelectric element, plating material and first layer of the circuit and terminating prior to reaching the ground of the ground layer. The cuts provide separated transducer elements in the axial direction, the transducer elements comprising individual ground electrodes and positive electrodes, wherein the individual ground electrodes are connected to one another through the first vias in electrical communication with the at least one ground, thereby obviating the need to reconnect the ground electrodes with further processing subsequent to the dicing operation.

In some embodiments of methods of making a transducer assembly described herein, the piezoelectric element is provided with a plurality of cuts in the axial direction, the cuts terminating prior to the ground electrode on the opposing side of the piezoelectric element and providing M separated transducer elements in the longitudinal direction transverse to the axial direction. In some embodiments wherein the piezoelectric element is provided with M separated transducer elements in the longitudinal direction, the cuts made in the piezoelectric element having a depth passing through the piezoelectric element, plating material and first layer of the circuit and terminating prior to reaching the ground of the ground layer, provide in the axial direction N separated groups of the M transducer elements, thereby providing an N×M array.

These and other embodiments are described in greater detail in the detailed description which follows.

DETAILED DESCRIPTION

Embodiments described herein can be understood more readily by reference to the following detailed description and examples and their previous and following descriptions. Elements, apparatus and methods described herein, however, are not limited to the specific embodiments presented in the detailed description and examples. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations will be readily apparent to those of skill in the art without departing from the spirit and scope of the invention.

In one aspect, circuits for transducer element arrays are described herein. In some embodiments, circuits described herein are flexible circuits. In some embodiments, circuits for transducer element arrays described herein permit facile connection of ground electrodes of transducer elements formed by one or more dicing operations.

In some embodiments, a circuit described herein comprises a first layer for receiving a transducer element array, a ground layer comprising at least one ground disposed over the first layer and a plurality of first vias corresponding to transducer elements of the array, the first vias extending through the first layer to the at least one ground and comprising first ends for receiving ground electrodes of the transducer elements and second ends electrically connected to the ground.

The term “via” denotes a construction comprising an accessway through one or more layers of a circuit described herein, the accessway comprising any suitable element for establishing electrical connection between electrically conducting elements within different layers of the circuit and/or with one or more electrical conductors external to the circuit. In some embodiments, the vias can be pads with plated holes, which can be made to be conductive by electroplating, or the holes can be filled with annular rings or rivets. Embodiments described herein are not limited to any particular type of via.

In some embodiments, a circuit described herein further comprises one or more ground vias for electrically connecting one or more grounds of the ground layer to an external circuit, such as that of an ultrasound system. In some embodiments, a ground via extends through the ground layer to the exterior of the circuit. In some embodiments, for example, a ground via extends laterally out of the ground layer. In some embodiments, a ground via extends into one or more layers adjacent to the ground layer.

A circuit described herein, in some embodiments, further comprises second vias corresponding to transducer elements of the array, the second vias extending through the first layer and comprising first ends electrically coupled to positive electrodes of the transducer elements and second ends electrically connected to one or more traces in electrical communication with circuitry external to the circuit, such as that of an ultrasound system. In some embodiments, at least one second via is associated with a positive electrode of each transducer element of the array.

In some embodiments, at least some of the second vias terminate in one or more additional layers disposed between the first layer and the ground layer of the circuit. In some embodiments, at least some of the second vias terminate in one or more additional layers disposed over the ground layer. In some embodiments, at least some of the second vias terminate in the ground layer. In some embodiments, a first number of second vias terminate in a different layer of the circuit than a second number of second vias.

In some embodiments, layers of a circuit described herein can be constructed from any desired material not inconsistent with the objectives of the present invention. In some embodiments, layers of a circuit described herein are constructed of flexible materials to provide a flexible circuit. In some embodiments, layers of a circuit described herein comprise one or more flexible dielectric polymeric materials. In some embodiments, a suitable flexible dielectric polymeric material comprises one or more polyimides. In some embodiments, for example, one or more layers of a circuit described herein comprise KAPTON® polyimide commercially available from DuPont of Wilmington, Del. Alternatively, in some embodiments, layers of a circuit described herein are constructed of one or more rigid or semi-rigid dielectric polymeric materials.

In some embodiments, a circuit described herein is suitable for interfacing with a transducer element array comprising a piezoelectric material separated into N transducer elements in the axial direction to provide an N×1 array. In some embodiments, N is 64 or a multiple of 64. In some embodiments, for example, N is 128, 192, 256, 320, 384, 448 or 512. In some embodiments, N is 96.

In some embodiments, a circuit described herein is suitable for interfacing with a transducer element array comprising a piezoelectric material separated into N transducer groups in the axial direction and M transducer elements in the longitudinal direction transverse to the axial direction to provide an N×M array. In some embodiments, N of an N×M array is 64 or a multiple of 64, including 128, 192, 256, 320, 384, 448 or 512. In some embodiments, N of an N×M array is greater than 512. In some embodiments, N of an N×M array described herein is 96. Moreover, in some embodiments M of an N×M array is selected from the group consisting of 3, 5, 7, 9 and 11. In some embodiments, a circuit described herein is suitable for interfacing with a transducer element array having an N×M construction according to Table I.

In some embodiments, a transducer element array interfacing with a circuit described herein is a curved array. In some embodiments, a transducer element array interfacing with a circuit described herein is a tightly curved array. In some embodiments, a circuit described herein is suitable for interfacing with a curved array or tightly curved array having any transducer element arrangement provided in Table I herein. In some embodiments, for example, a circuit described herein is suitable for interfacing with a curved array or a tightly curved array having transducer element arrangement of 192×5 or 256×5.

In some embodiments, a transducer element array of an ultrasonic transducer system described herein is a planar array.

In another aspect, ultrasonic transducer systems are described herein. In some embodiments, an ultrasonic transducer system comprises an array comprising a plurality of transducer elements, the transducer elements comprising individual positive electrodes and ground electrodes and a circuit coupled to the array, the circuit comprising a first layer for receiving the array, a ground layer comprising at least one ground disposed over the first layer and a plurality of first vias corresponding to transducer elements of the array, the first vias extending through the first layer to the at least one ground and comprising first ends electrically connected to individual ground electrodes of the transducer elements and second ends electrically connected to the ground of the ground layer. In some embodiments, a circuit of an ultrasonic transducer system described herein further comprises one or more ground vias for electrically connecting one or more grounds of the ground layer to an external circuit, such as that of an ultrasound system.

A circuit of an ultrasonic transducer system, in some embodiments, further comprises second vias corresponding to transducer elements of the array, the second vias extending through the first layer and comprising first ends electrically connected to positive electrodes of the transducer elements and second ends electrically connected to one or more traces in electrical communication with an ultrasound system. In some embodiments, at least one second via is associated with a positive electrode of each transducer element of the array.

In some embodiments, at least some of the second vias terminate in one or more additional layers disposed between the first layer and the ground layer of the circuit. In some embodiments, at least some of the second vias terminate in one or more additional layers disposed over the ground layer. In some embodiments, at least some of the second vias terminate in the ground layer. In some embodiments, a first number of second vias terminate in a different layer of the circuit than a second number of second vias.

In some embodiments, a transducer element array of an ultrasonic transducer system comprises a piezoelectric material separated into N transducer elements in the axial direction to provide an N×1 array. In some embodiments, a transducer element array of an ultrasonic transducer system comprises a piezoelectric material separated into N transducer groups in the axial direction and M transducer elements in the longitudinal direction transverse to the axial direction to provide an N×M array.

In some embodiments, a transducer element array of an ultrasonic transducer system described herein is a curved array. In some embodiments, a transducer element array of an ultrasonic system described herein is a tightly curved array. In some embodiments, a transducer element array of an ultrasonic transducer system described herein is a planar array. In some embodiments, a transducer element array of an ultrasonic transducer system has a transducer element arrangement selected from the arrangements provided in Table I.

FIG. 2is a side elevation cross-sectional view of an ultrasonic transducer system according to one embodiment described herein. The ultrasonic transducer system32ofFIG. 2comprises an N×1 transducer element array34comprising a plurality of transducer elements56, the transducer elements comprising a piezoelectric ceramic material. AsFIG. 2is a side elevation cross-sectional view of the transducer system32, the cross-section of a single transducer element56of the array34in conjunction with the section of the circuit70associated with the transducer element56is shown. The remaining transducer elements56of the array34and associated circuitry70having a similar construction extend along the axial direction. The transducer element56comprises an electrically conductive plating material36wrapped therearound. The plating material36is discontinuous at regions38to define a positive electrode40and ground electrode42of the transducer element56. Discontinuous regions38can be formed by a variety of processes including making deactivation cuts to remove the plating material36or etching the plating material36chemically and/or lithographically. In some embodiments, discontinuous regions38are provided by selectively depositing the plating material36on the transducer element56. Selective deposition of the plating material36, in some embodiments, is achieved by masking and/or other lithographic techniques, chemical etching and/or ion etching techniques.

The ground electrode42can extend about a portion of an upper side46of the transducer element56, over side walls44and across a lower side48of the transducer element56. The terms “upper” and “lower” are used for convenience to facilitate the discussion and are not meant to be limiting. Additionally, one or more acoustic matching layers54are coupled to one side of the transducer element array34.

The ultrasonic transducer system32ofFIG. 2also comprises a circuit70interfaced with the transducer element array34. As with the transducer element array34, the circuit70has an associated axial direction A, a longitudinal direction L that is transverse to the axial direction A, and a thickness direction T.

In the embodiment ofFIG. 2, the circuit70comprises a first layer74for receiving or interfacing with the transducer element array34and a ground layer78over the first layer74, the ground layer comprising a first ground90and a second ground92. Although two grounds90,92are illustrated in the embodiment ofFIG. 2, circuits comprising a single ground or more than two grounds in the ground layer are contemplated herein. At least one additional layer76is disposed between the first layer74and the ground layer78. In the embodiment ofFIG. 2, a backer50is coupled to the circuit70and can provide structural rigidity to the circuit70.

In some embodiments, at least one of the first90and second92grounds is provided on an exterior surface of the ground layer78, as opposed to within the ground layer78. In some embodiments, for example, at least one of the first90and second92grounds is disposed on the exterior surface of the ground layer78interfacing with the at least one additional layer76. In some embodiments, at least one of the first90and second92grounds is disposed on the exterior surface of the ground layer interfacing with the backer50.

The circuit70comprises first vias80extending through the first layer74and the at least one additional layer76to the first90and second92grounds of the ground layer78. The first vias80comprise first ends82electrically connected to the ground electrode42of transducer elements56of the array34and second ends84electrically connected to the first90or second ground92. Although two first vias80and two grounds90,92are illustrated inFIG. 2, embodiments described herein contemplate use of a single via80in the circuit70to electrically connect the ground electrode42of transducer element56to a single ground90of the ground layer78.

Moreover, in the embodiment illustrated inFIG. 2, first vias80extend in a vertical direction normal to layers of the circuit70. In some embodiments, first vias80can extend at one or more angles non-normal to layers of the circuit70. In some embodiments, first vias80can extend laterally through one more layers of the circuit70in additional to vertically.

The circuit70illustrated inFIG. 2further comprises second vias110extending through the first layer74. The second vias110comprise first ends116electrically connected to the positive electrode40of the transducer element56. The second vias110terminate in the at least one additional layer76, and the second ends118of the second vias are electrically connected to conductors or traces124in electrical communication with external circuitry, such as that of an ultrasound system. As described herein, the second vias can pass through the first layer and terminate in any layer over the first layer. In the embodiment ofFIG. 2, for example, the first vias110can also terminate in the ground layer78. In some embodiments, a first number of second vias terminate in a different layer of the circuit than a second number of the second vias.

In the embodiment ofFIG. 2, the conductors or traces124extend in the longitudinal direction (L) of the circuit70to the exterior of the at least one additional layer76where the traces124can be electrically connected to external circuitry, such as that of an ultrasound system. Although two second vias110are illustrated inFIG. 2, embodiments described herein contemplate use of a single second via110in the circuit70to electrically connect the positive electrode40to external circuitry through one or more conductors or traces124.

FIG. 3is a top plan cross-sectional view of the first layer74of the circuit70ofFIG. 2viewed along line3-3inFIG. 2. Individual transducer elements56of the N×1 transducer element array34defined by cuts128in the longitudinal direction of the piezoelectric ceramic material would be occluded by the first layer74in the presently illustrated view but are shown for reference purposes. Similarly, ground electrodes42, positive electrodes40and discontinuous regions38would also be occluded by the first layer74, but are shown for reference purposes.

A plurality of first vias80can extend through the first layer74, through the at least one additional layer76and into the ground layer78. The plurality of first vias80can be formed in the circuit70such that each of the first vias80can be outboard of the discontinuous regions38. In other words, each of the plurality of first vias80can be aligned with a respective one of the ground electrodes42of the transducer elements56when the circuit70is disposed on the transducer element array34, as shown inFIG. 3

In some embodiments, there can be at least two first vias80associated with each transducer element56. For example, one of the first vias80can be associated with a first longitudinal end portion94of the ground electrode42, and another one of the first vias80can be associated with a second longitudinal end portion96of the ground electrode42. The first vias80can be substantially aligned in the axial direction A along the first and second longitudinal end portions94,96of the ground electrodes42, as is shown inFIG. 3. While not shown inFIG. 3, one or more of the first vias80can be offset from the other first vias80in the axial direction A.

As inFIG. 2, each of the plurality of first vias80can have a first end82and a second end84. The first ends82of the first vias80can be adapted to facilitate operative connection to the ground electrodes42of the transducer elements56. In some embodiments, for example, the first ends82of the first vias80can include connection pads86. The second ends84of the first vias80can terminate within or external to the ground layer78. The second ends84of the first vias80can be adapted to facilitate operative connection to one or more of grounds in the ground layer78. In some embodiments, for example, the second ends84of the first vias80can include connection pads.

FIG. 5is a top plan cross-sectional view of the ground layer78of the circuit70ofFIG. 2, as viewed in the direction of the arrows associated with line5-5inFIG. 2. Individual transducer elements56of the N×1 transducer element array34defined by cuts128in the longitudinal direction of the piezoelectric ceramic material would be occluded by the ground layer78in the presently illustrated view but are shown for reference purposes. Similarly, discontinuous regions38in the plating material36would also be occluded by the ground layer78, but are shown for reference purposes.

The ground layer78can include one or more different traces, including, for example, a first ground90and a second ground92. The first and second grounds90,92can provide a common return path for signals in the circuit70. The first and second grounds90,92can be elongated continuous conductors. The first and second grounds90,92can be made of any suitable material and have any desired shape not inconsistent with the objectives of the present invention. In some embodiments, the first and second grounds90,92can be substantially parallel to each other. The first and second grounds90,92, in some embodiments, can extend in generally the axial direction A. As described herein, the second ends84of the first vias80can be operatively connected to a respective one of the grounds90,92. The term “operatively connected,” as used herein, can include direct and indirect connections.

Some of the plurality of first vias80can be united at the first ground90, and some of the plurality of first vias80can be united at the second ground92. The first and second grounds90,92can be taken outside the circuit70. To that end, there can be a ground via98associated with each of the grounds90,92. The ground vias98are different from the first vias80. For instance, as will be explained in more detail below, the first vias80operatively connect the ground electrodes42of individual transducer elements56to a respective one of the grounds90,92whereas the ground vias98operatively connect at least one of the grounds90,92to a conductor extending outside of the circuit70.

A ground via98can be operatively connected at a first end100to a respective ground90,92. The first end100may include a connection pad102or other suitable structure to facilitate operative connection. In some embodiments, a ground via98can extend from the ground layer78and into at least one additional layer76disposed between the ground layer78and the first layer74. Alternatively, in some embodiments, a ground via98can extend laterally or vertically out of the ground layer78.

FIG. 4is a top plan cross-sectional view of the at least one additional layer76of the circuit70ofFIG. 2, as viewed in the direction of the arrows associated with line4-4inFIG. 2. Individual transducer elements56of the N×1 transducer element array34defined by cuts128in the longitudinal direction of the piezoelectric ceramic material would be occluded by the at least one additional layer76in the presently illustrated view but are shown for reference purposes. Similarly, discontinuous regions38in the plating material36would also be occluded by the first layer74, but are shown for reference purposes.

The at least one additional layer76of the circuit70comprises ground vias98extending therein from the ground layer78as described herein. The ground vias98are operable to connect grounds90,92(not shown) of the ground layer78to an external circuit, such as that of an ultrasound system. In the at least one additional layer76, a conductor104can be operatively connected to a second end106of the ground via98. The second end106may include a connection pad108or other suitable structure to facilitate operative connection. The conductor104can extend generally in the longitudinal direction L to outside the circuit70. The conductor104can be operatively connected to a cable assembly (not shown) that can carry electrical signals to an ultrasound system (not shown).

The circuit70can include a plurality of second vias110. In the non-limiting embodiments illustrated inFIGS. 2-5herein, the plurality of second vias110extend from the first layer74of the circuit70and into a depth of the at least one additional layer76. The plurality of second vias110can be provided such that each second via110can be aligned with a positive electrode of respective one of the transducer elements56. In some embodiments, for example, the second vias110are inboard of the discontinuous regions38. Thus, each of the second vias110can be in line with a respective one of the positive electrodes40the transducer elements56when the circuit70is interfaced with the transducer element array34.

The plurality of second vias110can be distributed in any suitable manner not inconsistent with the objectives of the present invention. In some embodiments, the second vias110can be provided in a staggered arrangement, the staggered arrangement comprising a first subset110′ of the second vias110alternating with a second subset110″ of the second vias110, as is shown inFIG. 3. Each of the second vias110in the first subset110′ can be provided proximate to a first longitudinal end112of the positive electrode40of a respective one of the transducer elements56. Each of the second vias110in the second subset110″ can be provided proximate to a second longitudinal end114of the positive electrode40of a respective one of the transducer elements56. Such a staggered arrangement can be convenient for avoiding overcrowding of individual traces from the circuit70. Moreover, as described herein, second vias110can be terminated in different layers of the circuit70to mitigate or avoid overcrowding.

However, embodiments are not limited to an arrangement in which the plurality of second vias110is staggered. For instance, the second plurality of vias110can be substantially aligned in the axial direction A. Thus, it will be appreciated that the plurality of second vias110can be provided in any suitable location and arranged in any suitable manner with respect to the transducer elements56.

As illustrated inFIGS. 2-4, each of the second vias110can have a first end116and a second end118. The first ends116of the second vias110are operable to receive positive electrodes40of individual transducer elements56. The first ends116of the plurality of second vias110can include connection pads120(FIG. 3) and/or other features to facilitate operative connection to another item, such as one of the positive electrodes40of the transducer elements56.

In the embodiment ofFIG. 4, the second ends118of the second vias110terminate within the at least one additional layer76. The second ends118of the second vias can include connection pads122and/or other features to facilitate operative connection to another item. In some embodiments, conductors or traces124can be operatively connected to second ends118of the second vias110. The conductors or traces124can extend generally in the longitudinal direction L within the second layer76. In some embodiments, one or more conductors or traces124can include a jog portion126that extends around the first via80on the same transducer element56to prevent electrical shorting. The jog portion126can have any suitable configuration so long as the conductor124avoids contact with the first vias80. The conductors or traces124can be operatively connected to a cable assembly (not shown) that can carry electrical signals to an ultrasound system (not shown).

In some embodiments, it may be beneficial to configure the first, second and/or ground vias to minimize problems that would be caused if one or more of the vias80,98,110were to break or malfunction. For example, redundancy can be introduced into the system so that additional vias are provided in at least some locations. To that end, at least some of the vias80,98and/or110can be provided in pairs or in triplets. An example of an arrangement in which pairs of vias are provided is shown inFIG. 6.

As described herein, in some embodiments, a transducer element array of an ultrasonic transducer system comprises a piezoelectric material separated into N transducer groups in the axial direction and M transducer elements in the longitudinal direction transverse to the axial direction to provide an N×M array.

FIG. 7illustrates a side elevation cross-sectional view of a transducer system according to one embodiment described herein. The ultrasonic transducer system32ofFIG. 8comprises an N×M transducer element array34. The transducer element array34comprises a piezoelectric ceramic material60separated into N transducer element groups61in the axial direction and M transducer elements56in the longitudinal direction transverse to the axial direction to provide the N×M array. AsFIG. 7is a side cross-sectional view of the transducer system32, the cross-section of a single transducer element group61comprising M=3 transducer elements56in the longitudinal direction of the array34in conjunction with the section of circuitry70associated with the transducer elements56is shown. The remaining transducer element groups61of the array34and associated circuitry70having similar construction extend along the axial direction.

The piezoelectric ceramic material60of the transducer element array34comprises an electrically conducting plating material36wrapped therearound. A plurality of cuts62are provided in the plating material36and the piezoelectric ceramic material60to define3transducer elements56in the longitudinal direction of the single axial transducer group61illustrated. In the embodiment ofFIG. 7, the cuts do not pass through the plating material36on the opposing or lower side48of the piezoelectric ceramic material. Moreover, the plating material36is discontinuous at regions38. The cuts62in the plating material36in conjunction with the discontinuous regions38define positive electrodes40for the M=3 transducer elements56of the axial transducer group61.

The remaining portion of the plating material61defines a ground electrode42for each of the M=3 transducer elements56. The ground electrode42can extend about a portion of an upper side of the transducer group61, over side walls and across a lower side48of the transducer group61.

Alternatively, in some embodiments, the plating material36is selectively deposited on regions of the piezoelectric ceramic material60between the cuts62to define the positive electrodes40and the ground electrode42of the transducer elements56. Selective deposition of the plating material36, in some embodiments, is achieved by masking and/or other lithographic, chemical etching or ion etching techniques.

The ultrasonic transducer system32ofFIG. 7also comprises a circuit70interfaced with the transducer element array34. As with the transducer element array34, the circuit70has an associated axial direction A, a longitudinal direction L that is transverse to the axial direction A and thickness direction T.

In the embodiment ofFIG. 7, the circuit70comprises a first layer74for receiving or interfacing with the transducer element array34and a ground layer78over the first layer74, the ground layer comprising a first ground90and a second ground92. Although two grounds90,92are illustrated in the embodiment ofFIG. 7, circuits comprising a single ground or more than two grounds in the ground layer are contemplated herein. At least one additional layer76is disposed between the first layer74and the ground layer78. In the embodiment ofFIG. 7, a backer50is coupled to the circuit70and can provide structural rigidity to the circuit70.

In some embodiments, at least one of the first and second grounds is provided on an exterior surface of the ground layer78, as opposed to within the ground layer78. In some embodiments, for example, at least one of the first90and second92grounds is disposed on the exterior surface of the ground layer78interfacing with the at least one additional layer76. In some embodiments, at least one of the first90and second92grounds is disposed on the exterior surface of the ground layer interfacing with the backer50.

The circuit70comprises first vias80extending through the first layer74and the at least one additional layer76to the first90and second92grounds of the ground layer78. The first vias80comprise first ends82electrically connected to the ground electrode42of the transducer elements56of the transducer group61and second ends84electrically connected to the first90and second grounds92. Although two first vias80and two grounds90,92are illustrated inFIG. 7, embodiments described herein contemplate use of a single first via80in the circuit70to electrically connect the ground electrode42of transducer elements56to a single ground90of the ground layer78.

Moreover, in the embodiment illustrated inFIG. 7, first vias80extend in a vertical direction normal to layers of the circuit70. In some embodiments, first vias80can extend at one or more angles non-normal to layers of the circuit70. In some embodiments, first vias80can extend laterally through one more layers of the circuit70in additional to vertically.

The circuit70illustrated inFIG. 7further comprises second vias110extending through the first layer74. The second vias110comprise first ends116electrically connected to the positive electrode40of each of the transducer elements56of the transducer group61. The second vias110terminate in the at least one additional layer76, and the second ends118of the second vias are electrically connected to conductors or traces124in electrical communication with external circuitry, such as that of an ultrasound system. As described herein, the second vias can pass through the first layer and terminate in any layer over the first layer. In the embodiment ofFIG. 7, for example, the first vias110can also terminate in the ground layer78. In some embodiments, a first number of second vias terminate in a different layer of the circuit than a second number of the second vias to inhibit or prevent overcrowding.

In the embodiment ofFIG. 7, the conductors or traces124extend in the longitudinal direction (L) of the circuit70to the exterior of the at least one additional layer76where the traces124can be electrically connected to external circuitry, such as that of an ultrasound system.

FIG. 8is a top plan cross-sectional view of the first layer74of the circuit70ofFIG. 7viewed along line3-3inFIG. 7. Individual transducer groups61of the N×M transducer element array34defined by cuts128in the longitudinal direction of the piezoelectric ceramic material60would be occluded by the first layer74in the presently illustrated view but are shown for reference purposes. Similarly, the M=3 transducer elements56of each transducer group61defined but cuts62and the associated ground42and positive electrodes40would also be occluded by the first layer74, but are shown for reference purposes.

A plurality of first vias80can extend through the first layer74, through the at least one additional layer76and into the ground layer78(not shown). The plurality of first vias80can be formed in the circuit70such that each of the first vias80can be outboard of the discontinuous regions38. In other words, each of the plurality of first vias80can be aligned with a respective one of the ground electrodes42of the transducer elements56when the circuit70is disposed on the transducer element array34, as shown inFIG. 8.

In some embodiments, there can be at least two first vias80associated with each ground electrode42of the transducer element group61. For example, one of the first vias80can be associated with a first longitudinal end portion94of the ground electrode42, and another one of the first vias80can be associated with a second longitudinal end portion96of the ground electrode42. The first vias80can be substantially aligned in the axial direction A along the first and second longitudinal end portions94,96of the ground electrodes42, as is shown inFIG. 8. While not shown inFIG. 8, one or more of the first vias80can be offset from the other first vias80in the axial direction A.

As inFIG. 7, each of the plurality of first vias80can have a first end82and a second end84. The first ends82of the first vias80can be adapted to facilitate operative connection to the ground electrodes42of the transducer groups61. In some embodiments, for example, the first ends82of the first vias80can include connection pads86. The second ends84of the first vias80can terminate within or external to the ground layer78. The second ends84of the first vias80can be adapted to facilitate operative connection to one or more of grounds in the ground layer78. In some embodiments, for example, the second ends84of the first vias80can include connection pads.

The circuit70further comprises a plurality of second vias110. As illustrated inFIGS. 7-8, the second vias110are aligned with the positive electrodes40of the M=3 transducer elements56of the transducer element groups61. The second vias comprise first ends116electrically connected to the positive electrodes40of the transducer elements56. Moreover, in the embodiment illustrated inFIG. 8, the second vias110comprise connection pads and/or other structures120operable to facilitate electrical connection with the positive electrodes40of the transducer elements56.

The circuit70can include a plurality of second vias110. In the non-limiting embodiments illustrated inFIGS. 2-8herein, the plurality of second vias110extend from the first layer74of the circuit70and into a depth in the at least one additional layer76. The plurality of second vias110can be provided such that each second via110can be aligned with a positive electrode of respective one of the transducer elements56. In some embodiments, for example, the second vias110are inboard of the discontinuous regions38. Thus, each of the second vias110can be in line with a respective one of the positive electrodes40the transducer elements56when the circuit70is interfaced with the transducer element array34.

In another aspect, methods of making transducer assemblies are described herein. In some embodiments, a method of making a transducer assembly comprises providing a piezoelectric element partially covered with a plating material defining a ground electrode and at least one positive electrode and providing a circuit comprising a first layer for receiving the piezoelectric element, a ground layer comprising at least one ground disposed over the first layer and a plurality of first vias extending through the first layer to the at least one ground and comprising first ends for receiving the ground electrode of the piezoelectric element and second ends electrically connected to the at least one ground. The first layer of the circuit is interfaced with the piezoelectric element and the first ends of the first vias are placed in electrical communication with the ground electrode of the piezoelectric element. A plurality of cuts are made in the piezoelectric element having a depth passing through the piezoelectric element, plating material and first layer of the circuit and terminating prior to reaching the ground of the ground layer. The cuts provide separated transducer elements in the axial direction, the transducer elements comprising individual ground electrodes and positive electrodes, wherein the individual ground electrodes are connected to one another through the first vias in electrical communication with the at least one ground of the ground layer, thereby obviating the need to reconnect the ground electrodes with further processing subsequent to the dicing operation.

In some embodiments of methods of making a transducer assembly, the piezoelectric element is provided with a plurality of cuts in the axial direction, the cuts terminating prior to the ground electrode on the opposing side of the piezoelectric element and providing M separated transducer elements in the longitudinal direction transverse to the axial direction. In some embodiments wherein the piezoelectric element is provided with M separated transducer elements in the longitudinal direction, the cuts made in the piezoelectric element having a depth passing through the piezoelectric element, plating material and first layer of the circuit and terminating prior to reaching the ground of the ground layer, provide in the axial direction N separated groups of the M transducer elements.

In some embodiments of methods of making a transducer assembly, a circuit described herein is fabricated independently from the piezoelectric element comprising the plating material and subsequently interfaced with the piezoelectric element. In some embodiments of methods of making a transducer assembly, a circuit described herein is interfaced with the piezoelectric element comprising the plating material by fabricating the circuit directly on the piezoelectric element.

A non-limiting example of a method of making a transducer assembly described herein is now provided with reference toFIGS. 2-5. A piezoelectric ceramic material comprising electrically conductive plating material and discontinuous regions38defining a positive electrode40and ground electrode42can be formed in any suitable manner. Additionally, one or more matching layers54can be attached to one side of the piezoelectric ceramic material in any suitable manner. In some embodiments, the matching layers54can improve acoustic energy transmission efficiency

A circuit70is interfaced with the side of the piezoelectric ceramic material comprising discontinuous regions38. The first ends82of the first vias80of the circuit70can be operatively connected to the ground electrode42of the piezoelectric ceramic material in any suitable manner. For instance, the first end82of each first via80can be operatively connected to the ground electrode42by epoxy or other suitable adhesive and/or by physical engagement between the first vias80and the ground electrode42.

Moreover, the first ends116of the second vias110can be operatively connected to the positive electrode40of the piezoelectric ceramic material. In some embodiments, a backer50operable to provide structural integrity to the transducer system32is attached to the circuit70.

Individual transducer elements56are formed from the piezoelectric ceramic material by making a plurality of parallel dices or cuts128in the transducer assembly32, as shown inFIGS. 2-4. Such cuts can be formed using a dicing saw (not shown) or other suitable cutting device. The dicing saw can be brought into contact with the assembly from the patient side of the assembly32, that is, from the matching layer54side of the assembly. Thus, the dicing saw can cut through the one or more matching layers54, through the plating material36, through the piezoelectric material34, and into the circuit70. The dicing saw can penetrate the first and at least one additional layers74,76of the circuit70, terminating prior to the grounds90,92of the ground layer78. After the dicing operation, kerf filler (not shown) can be placed in the cuts128to provide structural support to the diced assembly.

Significantly, as the cuts terminate prior to the grounds90,92of the ground layer78of the circuit70, a common ground connection by way of the grounds90,92is maintained between the newly formed transducer elements56having individual or discrete ground electrodes42. Therefore, in some embodiments, no subsequent operation of reconnecting separated ground electrodes42of the transducer elements56is required.