ULTRASONIC TRANSDUCERS WITH ROW-COLUMN ADDRESSING

Description

Domaine technique

[0001] The present description relates to ultrasonic transduction devices comprising an array of elementary ultrasonic transducers electrically connected by row and column electrode arrays called row-column addressing ultrasonic transduction devices or RCA (Row Column Addressing) ultrasonic transduction devices.

[0002] US2019 / 328360, US2021 / 302388 and US4550606 describe examples of ultrasonic transduction devices. US2019 / 328360 discloses an ultrasonic transducer comprising a first piezoelectric layer stacked on a second piezoelectric layer to form a stack. The first piezoelectric layer has one main face metallized to form a first electrode array and the other main face metallized to form a first ground electrode. The second piezoelectric layer has one main face metallized to form a second electrode array and the other main face metallized to form a second ground electrode, the second electrode array being oriented at an angle relative to the first electrode array. Technique antérieure

[0003] Row-column addressing ultrasound transduction devices have become increasingly attractive in the field of ultrasound imaging because they allow simultaneous imaging in at least two planes, and can also be used for 3D volume imaging.

[0004] One of the main advantages of RCA transducers is the reduced number of electronic circuits required to drive the transducer elements. For an array composed of R rows and C columns, R+C drive channels are typically required in the case of an RCA array, whereas typically RxC channels are required for a fully populated array, i.e., one in which each elementary transducer is connected individually. In an application in which R = C, an electronic drive system with typically 64, 128 or 256 channels can drive an RCA device with a number of elements of 32x32, 64x64 or 128x128, respectively, whereas for a fully populated ultrasonic transducer device, the maximum number of elementary transducers will be limited to 8x8, 11x11 or 16x16, respectively.

[0005] For applications in which the electronic transducer control circuits are remote from the probe comprising the ultrasonic transducer array, an RCA array advantageously reduces the number of coaxial cables between the probe and the remote electronic system. Alternatively, reducing the number of channels advantageously allows the electronic control circuits to be integrated into the probe as close as possible to the elementary transducer array.For applications where printed circuit board (PCB) or flexible (flex) circuit board (FCB) interconnects are used to connect transducers to coaxial cables or to onboard driver electronics located close to the transducers, RCA transducers advantageously reduce the number of interconnects and therefore allow for less complex PCBs by reducing the number of PCB layers required as well as the number of interlayer connections (vias). Thinner PCBs reduce the impact on acoustic propagation, but, as will be discussed later, impedance mismatch caused by PCB materials is still a problem.

[0006] There figure 1 illustrates an example of an RCA transducer 10, comprising a layer of active material 12 (e.g., a piezoelectric, piezocomposite, or single-crystal material), a row interconnection network 14 (R), a column interconnection network 16 (C), an acoustic impedance matching layer 18, and a backside layer 20. The major surfaces of the active material 12 are fully or partially metallized in the areas facing the column 16 and row 14 networks (not shown in the figure). The acoustic impedance matching layer 18 is a layer or layers of material having an acoustic impedance whose value lies between the acoustic impedance of the layer of active material 12 and the acoustic impedance of an object being imaged (e.g., a human body) to optimize the transmission of the acoustic wave between the two media.The main outer surface of the impedance matching layer therefore constitutes the output face of the acoustic waves emitted by the transducer. The rear face layer 20 is a layer or a multilayer of one or more acoustically absorbent materials to avoid parasitic reflections of acoustic waves. By convention, the row interconnection network 14 (R) is located between the active material layer 12 and the rear face material layer 20, and the column interconnection network 16 (C) is located between the active material layer 12 and the acoustic material layer 18.

[0007] However, the presence of interconnecting materials, including for example electrically insulating materials such as polyimide and electrically conductive materials such as copper, may adversely affect the performance of the RCA ultrasonic transducing device 10, as will be discussed later, and the fabrication / assembly of the conventional interconnecting structure is complicated by the fact that the two electrode arrays (R array electrodes & C array electrodes) must be interconnected at opposite major surfaces (faces) of the active material layer 12.

[0008] Regarding the interconnect materials, the RCA ultrasonic transducer device 10 requires at least the interconnect network 16 (C) between the active material layer 12 and the acoustic impedance matching layer 18. Some disadvantages of the interconnect network 16 (C) include impedance mismatch between the active material layer 12, the interconnect network 16 (C) and the acoustic impedance matching layer 18, and poor uniformity between the elements. Regarding the impedance mismatch, the interconnect network 16 (C) comprises an insulating material of low acoustic impedance, typically 3 MRayl, relative to the active material layer 12, typically 30 MRayl, and, therefore, creates a significant acoustic impedance mismatch between the active material layer 12 and the acoustic matching layer 18.A possible solution could be that the interconnect layer extends only partially above the metallized surfaces of the column array. Typically the interconnect layer covers one (or both) end(s) of the metallized surface extensions of the column array and extends along these metallized surfaces above some lateral elements of the row array. In such a configuration, the height of the interconnect layer creates a gap between the metallized surfaces of the column array and the layer of acoustic material 12. Even if the gap can be filled with a material, regarding uniformity, the acoustic properties are consequently not identical over the entire surface of the transducer, depending on the length of the extension of the interconnect layer over the metallized surfaces of the column array, the acoustic loading, i.e. the impedance seen by a part of the elements, is not the same.Regarding the quality of acoustic propagation, it is always desirable to have direct contact between the layer of active material 12 and the acoustic adaptation layer 18, or failing that to have an adhesive material interposed between them as thin as possible. Résumé de l'invention

[0009] One embodiment provides a row-column addressing matrix ultrasonic transduction device, comprising: a metallized active material plate comprising an active material plate having a first main surface and a second main surface opposite the first main surface, a first main surface metal layer on the first main surface, and a second main surface metal layer on the second main surface; an acoustic impedance matching layer attached to the second main surface metal layer; a first set of parallel cutting notches oriented in a first direction, said notches of the first set extending through the entire thickness of the metallized active material plate and along the entire length of the metallized active material plate in the first direction, and individualizing the second main surface metal layer into a set of column electrodes;a second set of parallel cutting notches oriented in a second direction different from the first direction, said notches of the second set extending through the entire thickness of the first main surface metal layer and through at least a portion of the thickness of the active material plate, and over the entire length of the metallized active material plate in the second direction, and individualizing the first main surface metal layer into a set of row electrode lines and a first external row of column electrode contacts, each column electrode contact of the first external row of column electrode contacts being electrically connected to a respective column electrode of the set of column electrodes;and an interconnect layer comprising a substrate of an electrically insulating material, a first set of conductive traces on the substrate, each trace of the first set of conductive traces being in electrical contact with a respective one of the first outer row of column electrode contacts, and a second set of conductive traces on the substrate, each trace of the second set of conductive traces being in electrical communication with a respective one of the row electrode lines. ;

[0010] According to one embodiment, each column electrode contact of the first outer row of column electrode contacts is electrically connected to the corresponding respective column electrode of the set of column electrodes by a respective column electrode connector of a first set of column electrode connectors formed in a first side surface metal layer covering a first side surface of the active material plate, the column electrode connectors of the first set of column electrode connectors being individualized by the cutting notches of the first set of cutting notches.

[0011] According to one embodiment, each column electrode contact of the first outer row of column electrode contacts is electrically connected to the corresponding respective column electrode of the column electrode assembly by a metallized via vertically passing through the active material plate.

[0012] According to one embodiment, the substrate of the interconnection layer has an inner surface, the first set of conductive tracks and the second set of conductive tracks are on the inner surface of the substrate, and the first set of conductive tracks forms a first distribution of interconnections of the interconnection layer, and the second set of conductive tracks forms a second distribution of interconnections of the interconnection layer.

[0013] According to one embodiment, the substrate of the interconnection layer has an inner surface, an outer surface, vias respectively aligned with the first outer row of column electrode contacts, and respective via connectors in the vias, the first set of conductive traces is on the outer surface of the substrate and is in electrical communication with respective column electrode contacts of the first outer row of column electrode contacts by means of via connectors, and the second set of conductive traces is on the inner surface of the substrate, and the first set of conductive traces and the second set of conductive traces form a first interconnection distribution of the interconnection layer.

[0014] According to one embodiment, the second set of parallel cutting notches further individualizes a second outer row of column electrode contacts, each column electrode contact of the first outer row of column electrode contacts being electrically connected to a respective column electrode of the set of column electrodes.

[0015] According to one embodiment, the first and second directions are orthogonal.

[0016] According to one embodiment, the first set of cutting notches and the second set of cutting notches are filled with a polymeric material.

[0017] According to one embodiment, the interconnection layer is a flexible printed circuit board.

[0018] According to one embodiment, the device further comprises a set of backside layers attached to the interconnect layer.

[0019] Another embodiment provides a method of manufacturing a row-column addressing matrix ultrasonic transduction device, the method comprising: providing a metallized active material blank comprising an active material blank having a first major surface and a second major surface opposite the first major surface, a first major surface metal layer on the first major surface, and a second major surface metal layer on the second major surface, the metallized active material blank having a width Wp and a length Lp; cutting the metallized active material blank to individualize a metallized active material blank from the metallized active material blank; attaching an acoustic impedance matching layer to the second major surface metal layer of the metallized active material blank;completely cutting the metallized active material plate in a first direction to form a first set of parallel cutting notches, the first set of cutting notches forming in the second main surface metal layer a set of column electrodes; partially cutting the metallized active material plate in a second direction to form a second set of parallel cutting notches, the second set of cutting notches forming in the first main surface metal layer rows of row electrodes and a first outer row of column electrode contacts, each column electrode contact of the first outer row of column electrode contacts being electrically connected to a respective column electrode of the set of column electrodes;providing an interconnect layer comprising a substrate of an electrically insulating material, a first set of conductive traces on the electrically insulating substrate, a second set of conductive traces on the electrically insulating substrate; connecting each trace of the first set of conductive traces to be in electrical communication with a respective one of the first outer row of column electrode contacts; and connecting each trace of the second set of conductive traces in electrical contact with a respective one of the rows of row electrodes.;

[0020] According to one embodiment, each column electrode contact of the first outer row of column electrode contacts is electrically connected to the corresponding respective column electrode of the set of column electrodes by a respective column electrode connector of a first set of column electrode connectors formed in a first side surface metal layer of the metallized active material plate, covering a first side surface of the active material plate, the column electrode connectors of the first set of column electrode connectors being individualized by the cutting notches of the first set of cutting notches.

[0021] According to one embodiment, the metallized active material plate has a length La less than the length Lp of the raw metallized active material plate and a width Wa equal to the width Wp of the raw metallized active material plate.

[0022] According to one embodiment, each column electrode contact of the first outer row of column electrode contacts is electrically connected to the corresponding respective column electrode of the set of column electrodes by a metallized via of the metallized active material plate, vertically passing through the active material plate.

[0023] According to one embodiment, the metallized active material plate has a length La less than the length Lp of the raw metallized active material plate and a width Wa less than the width Wp of the raw metallized active material plate. Brève description des dessins

[0024] Embodiments will be described below in relation to the attached figures and examples provided for illustrative purposes without limiting the scope of the claims: There figure 1 is a simplified diagram of a typical exploded interconnect structure of an RCA ultrasonic transduction device. The figure 2 is a perspective view of a raw plate of active material according to the invention. The figure 3 is a perspective view of the raw active material plate of the figure 2 after metallization to form a metallized active material plate. The figure 4 is a perspective view of a metallized active material plate resulting from cutting the raw metallized active material plate of the figure 3 . There figure 5 is a perspective view of the metallized active material plate of the figure 4 attached to an acoustic impedance matching layer to form an intermediate assembly. The figure 6 is a perspective view of the intermediate assembly of the figure 5 after completely cutting the metallized active material plate in a first direction to form a first set of parallel saw cuts. The figure 7 is a perspective view of the intermediate assembly of the figure 6 after partially cutting the metallized active material plate in a second direction to form a second set of parallel saw cuts. The figure 8 is a perspective view of the intermediate assembly of the figure 7 after fixing an interconnection layer. The figure 9 is an enlarged view of a corresponding part of the intermediate assembly of the figure 8 . There figure 10 is a perspective view of a line and column array transducer assembled according to the invention. figure 11 is a perspective view of the intermediate assembly after partial cutting of a metallized active material plate to create saw cuts, in which the saw cuts are filled with a polymer material according to an alternative embodiment of the invention. figure 12 is a perspective view of the intermediate assembly of the figure 11 after fixing an interconnection layer. The figure 13 is a perspective view of an intermediate assembly according to another embodiment of the invention, in which a first set of conductive traces is located on an outer surface of a substrate of an interconnection layer and a second set of conductive traces is located on an inner surface of the substrate of the interconnection layer. figure 14 is a perspective view of a plate of active material after metallization according to another embodiment. The figure 15 is a perspective view of a metallized active material plate resulting from cutting the metallized active material plate from the figure 14 . There figure 16 is a perspective view of an intermediate assembly after partial cutting of the metallized active material plate of the figure 15 in first and second directions. Description des modes de réalisation

[0025] Details of one or more embodiments of the subject matter described herein are set forth in this document. Modifications to the embodiments described herein, as well as other embodiments, will be apparent to those skilled in the art after studying the information given in this document. The information given in this document and, in particular, the specific details of the exemplary embodiments described are provided primarily for clarity and ease of understanding and are not limiting. In the event of a conflict, the description in this document, including definitions, shall take precedence.

[0026] Although the following terms are assumed to be well known to those skilled in the art, definitions are provided to facilitate the explanation of the subject matter described herein.

[0027] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art in the relevant field. Similarly, the methods, devices, and materials described herein enable the practice or testing of the present invention, although other methods, devices, and materials similar or equivalent to those described herein may be used to achieve the same ends.

[0028] The terms "a", "an", and "the" mean "one or more" when used in this application, including in the claims. Thus, for example, reference to "a transducer" includes a plurality of such transducers and so on.

[0029] Unless otherwise specified, all numbers expressing compositional components, properties such as frequency, etc., used in the description and claims are to be understood as being modified in all circumstances by the term "about". Therefore, unless otherwise specified, the numerical parameters indicated in these descriptions and claims are approximations which may vary depending on the desired properties sought to be obtained by the subject matter described herein.

[0030] As used herein, the term "about," when assigned to a value or quantity, is intended to incorporate variations of ±20% in some embodiments, ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, ±0.5% in some embodiments, and ±0.1% in some embodiments from the stated quantity, as such variations are appropriate to implement the disclosed subject matter.

[0031] As used herein, ranges may be expressed as starting "from about" a particular value, and / or up to "about" another particular value. It will also be understood that there are a number of values described herein, and that each value is also described herein as being "about" that particular value in addition to the value itself. For example, if the value "10" is described, then "about 10" is also described. It will also be understood that each unit between two particular units is also described. For example, if 10 and 15 are described, then 11, 12, 13, and 14 are also described.

[0032] The terms "transducer array" or "transducer network" or "ultrasonic transduction device" are used herein to describe a transducer device obtained by a geometric arrangement of a plurality of transducers (i.e., transducer elements) having dimensions compatible with the focusing and deflection characteristics of an ultrasonic beam.

[0033] The terms "elementary transducer" or "transducer element" or "transducer" are used herein to describe an individual ultrasonic transducer component of a transducer array. Typically, an elementary transducer of a transducer array has planar dimensions suitable for electronic focusing and deflection of ultrasonic beams. Each transducer element or elementary transducer is provided with two conductive electrodes. A conductive electrode can be formed either by both subtractive and additive processes in the case of a cut-free array of elements, or etched together with the active material layer during the element individualization process.

[0034] A row-column addressed (RCA) ultrasonic transducer device, as previously discussed, is an array transducer having "R" rows of electrodes and "C" columns of electrodes on opposite sides of an active material, where an R-row interconnection network has row traces that are connected to the rows on a first major surface of the transducer array and a C-column interconnection network is connected to the columns on a second major surface of the array opposite the first surface. Individual transducer elements are actuated by applying appropriate signals to a row trace of the R-row interconnection network and to a column trace of the C-column interconnection network corresponding to the transducer element being activated.

[0035] As used herein, the term "active material" means an ultrasonic transducer material that undergoes compression and stretching in order to convert electrical energy into ultrasound or vice versa. Examples of such active materials include a piezoelectric material such as PZT, KNN, BaTiO3, PMN-PT, LNO3 either in the form of a ceramic or single-crystal material, constituting the entire volume of the active material or in composite form (mixed with a polymer material), as well as a piezoelectric polymer such as PVDF. An "active material plate" is a thin, flat sheet of an active material. An "active material blank" is a large, thin, flat sheet of an active material from which smaller plates of the active material are cut or otherwise individualized.

[0036] As used herein, the term "acoustic impedance matching layer" or "matching layer" means a layer or layers of a material attached to a front side of the active material of the ultrasound transducer having an acoustic impedance whose value is between that of the acoustic impedance of the active material and that of the acoustic impedance of the element to be imaged (e.g., human tissue). This impedance matching layer minimizes the reflection of the ultrasound wave at the interface between the active material and the medium to be imaged, e.g., a patient's body.

[0037] As used herein, the term "back material" or "backing" means a layer or layers of one or more acoustic damping materials attached to a back face of the active material of the ultrasonic transducer to prevent spurious reflections of acoustic waves.

[0038] As used herein, the terms "cut" and "carve" mean cutting a material or materials joined together to form trenches or saw cuts in the active material or to individualize a slab of active material from a raw slab. A preferred means for cutting or carve is a rotating circular diamond wire saw. "Cut" and "carve" may also include laser cutting or chemical etching as means for cutting or carve.

[0039] As used herein, the term "kerf" means a slot or notch formed by cutting, such as with a saw or other cutting means (see "cutting").

[0040] As used herein, the term "C-direction" means a column direction of the elementary transducer array.

[0041] As used herein, the term "R direction" means a line direction of the elementary transducer array.

[0042] As used herein, the term "interconnect layer" means a layer of insulating material on which electrical traces are formed to interconnect electrodes of individual elements of an RCA transduction device with an imaging system.

[0043] As used herein, the term "fan-out" or "interconnect fan-out" refers to the electrical interconnections between the transducer elements and the upstream electrical connections to match the pitch and direction of the electrical contacts at each end of the interconnect. Interconnect distribution is achieved, for example, with a flexible printed circuit board.

[0044] As used herein, the term "anisotropic conductive film" means an adhesive interconnect system for forming electrical and mechanical connections from electronic control circuits to substrates.

[0045] The term "imaging system" is used herein to describe an apparatus that includes a signal generator, a signal processor, and a user interface. The signal generator is for generating signals for activating transducer elements of an ultrasonic transducer to generate acoustic waves. The signal processor is for processing the signals generated by the transducer elements in response to acoustic waves received by the transducer elements. The signal processor further includes an image processor for generating images from the processed signals. The user interface is for displaying the generated images and receiving additional inputs from a user of the imaging system. Such imaging systems are commercially available and known to those skilled in the art, so the details of the elements and operation of such imaging systems will not be described further herein.

[0046] A first example of a method of manufacturing a row and column array ultrasonic transducer according to the invention begins with the provision, as illustrated in figure 2 , of a raw plate of active material 102 having a first main surface 104 and a second main surface 106 opposite the first main surface 104. On sides extending between the first main surface 104 and the second main surface 106, the raw plate of active material 102 also has a first side surface 108, a second side surface 110 opposite or facing the first side surface 108, a third side surface 112, and a fourth side surface 114 opposite or facing the third side surface 112.

[0047] The raw active material plate 102 is then metallized to form a metallized raw active material plate 202, as shown in figure 3 . Appear in figure 3 a first main surface metal layer 204, a second main surface metal layer 206, a first side surface metal layer 208, a second side surface metal layer 210, a third side surface metal layer 212, and a fourth side surface metal layer 214. Compared to the raw active material plate 102 ( figure 2 ), the first main surface metal layer 204 is on the first main surface 104, the second main surface metal layer 206 is on the second main surface 106, the first side surface metal layer 208 is on the first side surface 108, the second side surface metal layer 210 is on the second side surface 110, the third side surface metal layer 212 is on the third side surface 112, and the fourth side surface metal layer 214 is on the fourth side surface 114. The first side surface metal layer 208, the second side surface metal layer 210, the third side surface metal layer 212, and the fourth side surface metal layer 214 are electrically connected to the first main surface metal layer 204 and the second main surface metal layer 206.This is hereinafter referred to as a "wrap-around" metallization. The raw plate of active material 102 (. figure 2 ) is therefore fully metallized, although only one of the first side surface metal layer 208 and the second side surface metal layer 210 is needed to provide a single interconnection layer for both the R array electrodes and the C array electrodes, as will be discussed later. The metallized active material blank slab 202 has a width, Wp, and a length, Lp.

[0048] An example of a metallization process for an active material plate involves the deposition of one or more layers of electrically conductive materials, for example gold (Au) or copper (Cu), nickel (Ni) or silver (Ag). The deposition process is achieved, for example, by physical vapor deposition (PVD) or chemical vapor deposition (CVD).Thus, the first main surface metal layer 204, the second main surface metal layer 206, and the lateral surface metal layers 208, 210, 212, 214 are very thin layers ranging from a few tens (e.g., 20 to 40) of nanometers up to a few (e.g., 2 to 4) micrometers compared to the dimensions of the raw active material plate whose thickness is in the range from a few tens (e.g., 20 to 40) of micrometers up to a few (e.g., 2 to 4) millimeters and lateral dimensions ranging from a few (e.g., 2 to 4) millimeters to hundreds of millimeters. Thus, even though the raw active material plate 102 is under the first main surface metal layer 204, the second main surface metal layer 206, and the side surface metal layers 208, 210, 212, 214 and is therefore not visible in . figure 3 , the person skilled in the art will understand that the width, length, and thickness of the raw active material plate 102 are substantially the same as the width, Wp, length, Lp, and thickness of the metallized raw active material plate 202.

[0049] The first example of a method for manufacturing an ultrasonic transducer according to the invention then comprises a step of cutting the raw metallized active material plate 202 in the width direction at two cutting locations 216, 218 to individualize a metallized active material plate 302, as shown in figure 4 , from the raw metallized active material plate 202. The metallized active material plate 302 has a width Wa equal to Wp, a length La less than the length Lp, and a thickness equal to the thickness of the raw metallized active material plate 202. The length La is equal to the final length of the RCA ultrasonic transduction device.

[0050] At the center of the metallized active material plate 302 is an active material plate 303 individualized from the raw active material plate 102 ( figure 2 ). The active material plate 303 has a first main surface corresponding to the first main surface 104 of the active material raw plate 102, a second main surface opposite the first main surface and corresponding to the second main surface 106 of the active material raw plate 102, a first side surface extending between the first main surface and the second main surface and corresponding to the first side surface 108 of the active material raw plate 102, and a second side surface corresponding to the second side surface 110 of the active material raw plate 102. The thickness of the active material plate 303 (i.e., the active material plate thickness) corresponds to the active material raw plate thickness.The first main surface metal layer 204, the second main surface metal layer 206, the first side surface metal layer 208 and the second side surface metal layer 210 cover the first main surface, the second main surface, the first side surface and the second side surface, respectively, of the active material plate 303. Therefore, the first main surface, the second main surface, the first side surface and the second side surface of the active material plate 303 are not visible in . figure 4 .

[0051] There figure 4 illustrates the active material plate 303 having exposed side surfaces 304, 306. The figure 4 also illustrates exposed side surfaces of the first main surface metal layer 204, the second main surface metal layer 206, the first side surface metal layer 208 and the second side surface metal layer 210. Advantageously, the first side surface metal layer 208 and the second side surface metal layer 210 still electrically connect the first main surface metal layer 204 and the second main surface metal layer 206 (i.e., a "wrap-around" metallization of the active material plate 303 also referred to as "wrap-around").

[0052] There figure 5 illustrates the metallized active material plate 302 after attachment of an acoustic impedance matching layer 402 to its second major surface metal layer 206 to form an intermediate assembly. Optionally, if provided in the acoustic stack structure, an additional acoustic impedance matching layer (or layers) 404 could also be attached to the acoustic impedance matching layer 402. Although not shown in figure 5 , the acoustic stack may also include an impedance mismatching layer that forms an acoustic mirror ("dematching layer" in English) - attached to the first main surface metal layer 204 of the active material plate 302.

[0053] The acoustic impedance matching layer 402 and the acoustic impedance matching layer(s) 404 are preferably made of a polymer material loaded with particles to achieve the desired acoustic properties (e.g., speed of sound), or graphite layers.

[0054] The attachment of the acoustic impedance matching layer 402 to the second main surface metal layer 206 is preferably carried out by adhesive bonding by depositing a thin layer of glue therebetween and polymerizing it by heat treatment (ranging from room temperature to 100°C) and under pressure applied to the stack. According to a variant, the attachment is obtained by a molecular bonding process ("wafer bonding").

[0055] There figure 6 illustrates the intermediate assembly after the metallized active material plate 302 has been completely cut (i.e., completely cut through a thickness of the metallized active material plate 302) in a first direction (i.e., a direction C as indicated by the directional arrows referenced "C") to form a first set of saw cuts 502, 504, 506, 508, 510, 512, 514, 516.The first set of saw cuts 502, 504, 506, 508, 510, 512, 514, 516 forms in the second main surface metal layer 206 a set of column electrodes at the interface of the second main surface metal layer 206 and the acoustic impedance matching layer 402, and forms in the first side surface metal layer 208 a first set of column electrode connectors 518, 520, 522, 524, 526, 528, 530, 532, 534 that electrically connect the column electrodes to the first main surface metal layer 204. Correspondingly, the first set of saw cuts 502, 504, 506, 508, 510, 512, 514, 516 also forms in the second side surface metal layer 210 a second set of column electrode connectors 538, 540, 542, 544, 546, 548, 550, 552, 554.The first set of column electrode connectors 518, 520, 522, 524, 526, 528, 530, 532, 534 and the second set of column electrode connectors 538, 540, 542, 544, 546, 548, 550, 552, 554 electrically connect the column electrodes to the first main surface metal layer 204. The acoustic impedance matching layer 402 serves to hold the fully cut metallized active material plate 302 in place.

[0056] Alternatively, the cutting depth of the first set of saw cuts 502, 504, 506, 508, 510, 512, 514, 516 may also extend through the impedance matching layers 402 and 404 (only a partial cut of the impedance matching layer 402 is shown in figure 6 ). This depth extension is necessary if the impedance matching layer 402 or the impedance matching layers 402 and 404 are electrically conductive in order to avoid a short circuit between the column electrodes. In this case, the entire stack is previously fixed on a temporary mechanical holding substrate which is then removed after the last step of manufacturing the transducer.

[0057] The first direction (i.e. direction C) is represented in figure 6 as the width direction, without being limiting. The only significant limitation on the first direction is that it causes the first set of saw cuts 502, 504, 506, 508, 510, 512, 514, 516 to form in the second main surface metal layer 206 the first set of column electrodes at the interface of the second main surface metal layer 206 and the acoustic impedance matching layer 402, and to form in the first side surface metal layer 208 the first set of column electrode connectors 518, 520, 522, 524, 526, 528, 530, 532, 534.

[0058] There figure 7 illustrates the intermediate assembly after partially cutting the metallized active material plate 302 (i.e., cutting less than the thickness of the active material plate 303) in a second direction (i.e., an R direction, as indicated by the directional arrows referenced "R") to form a second set of saw cuts 602, 604, 606, 608, 610, 612, 614, 61, 618, 620, 622. The cutting depth must be less than the thickness of the active material plate 303 to preserve electrical continuity of the column electrode assembly at the interface of the second main surface metal layer 206 and the acoustic impedance matching layer 402.The second set of saw cuts 602, 604, 606, 608, 610, 612, 614, 616, 618, 620, 622 forms in the first main surface metal layer 204 row electrode lines 624, 626, 628, 630, 632, 634, 636, 638, 640, 642, a first outer row of column electrode contacts 644, 646, 648, 650, 652, 654, 656, 658, 660, and a second outer row of column electrode contacts 662, 664, 668, 670, 672, 674, 676, 678, 680. The first external row of column electrode contacts 644, 646, 648, 650, 652, 654, 656, 658, 660 is electrically connected respectively to the first set of column electrode connectors 518, 520, 522, 524, 526, 528, 530, 532, 534 (. figure 6 ), and the second outer row of column electrode contacts 662, 664, 668, 670, 672, 674, 676, 678, 680 is electrically connected respectively to the second set of column electrode connectors 538, 540, 542, 544, 546, 548, 550, 552, 554 ( figure 6 ). Thus, the previously described "enveloping" metallization of the active material plate 303 ( figure 4 ) allows the set of column electrodes (i.e., the array electrodes C) at the interface of the second main surface metal layer 206 and the acoustic impedance matching layer 402 to be electrically connected respectively to the first outer row of column electrode contacts 644, 646, 648, 650, 652, 654, 656, 658, 660 and the second outer row of column electrode contacts 662, 664, 668, 670, 672, 674, 676, 678, 680.Advantageously, the first external row of column electrode contacts 644, 646, 648, 650, 652, 654, 656, 658, 660 and the second external row of column electrode contacts 662, 664, 668, 670, 672, 674, 676, 678, 680 form particular interconnection areas for C electrodes on opposite edges of the first main surface metal layer 204 and on the same side of the metallized active material plate 302 as the row electrode lines 624, 626, 628, 630, 632, 634, 636, 638, 640, 642 (i.e., the array electrodes R), forming a single layer interconnection for both the R-array electrodes and the C-array electrodes.

[0059] Note that only one of the first outer row of column electrode contacts 644, 646, 648, 650, 652, 654, 656, 658, 660 and the second outer row of column electrode contacts 662, 664, 668, 670, 672, 674, 676, 678, 680, and only one corresponding connector of the first set of column electrode connectors 518, 520, 522, 524, 526, 528, 530, 532, 534 and the second set of column electrode connectors 538, 540, 542, 544, 546, 548, 550, 552, 554 ( figure 6 ) is required to contact the array electrodes C. However, providing both the first outer row of column electrode contacts 644, 646, 648, 650, 652, 654, 656, 658, 660 and the second outer row of column electrode contacts 662, 664, 668, 670, 672, 674, 676, 678, 680 (and the first set of column electrode connectors 518, 520, 522, 524, 526, 528, 530, 532, 534 and second set of column electrode connectors 538, 540, 542, 544, 546, 548, 550, 552, 554 correspondents ( figure 6 )) allows more distribution options for the interconnect layer, as will be discussed later.

[0060] It will be further noted that, in the intermediate set represented in figure 7 , the partial cutting of the metallized active material plate 302 to form the second set of saw cuts 602, 604, 606, 608, 610, 612, 614, 61, 618, 620, 622 also forms in the active material plate 302 the transducer elements in a row and column array (i.e. the pillars shown in figure 7 ). The person skilled in the art will understand that the order of the complete cutting and the partial cutting of the metallized active material plate 302 could be reversed, so that the partial cutting is carried out before the complete cutting of the metallized active material plate 302. Thus, it will be understood that the order of the complete cutting and the partial cutting is not important for forming in the active material plate 302 transducer elements in an array of lines and columns (i.e., the pillars shown in figure 7 ).

[0061] The second direction (R direction) is oriented at an orientation angle relative to the first direction (C direction). As shown, the orientation angle is orthogonal or 90 degrees. Advantageously, with an orthogonal orientation angle, the second set of saw cuts 602, 604, 606, 608, 610, 612, 614, 61, 618, 620, 622 may be limited to extend through the exposed side surfaces 34, 306 of the active material plate 302. However, the orientation angle may include other angles preferably between, and including, 80 degrees and 90 degrees, such that the second set of saw cuts 602, 604, 606, 608, 610, 612, 614, 61, 618, 620, 622 extends through the exposed side surfaces 304, 306 of the active material plate 302. As an example, a Small deviation (<10°) from a 90° angle may be advantageous for some imaging applications where certain imaging directions are preferred.The deviation from a 90° angle cannot be too great, because the second set of saw cuts 602, 604, 606, 608, 610, 612, 614, 61, 618, 620, 622 would no longer extend through the exposed side surfaces 304, 306 of the active material plate 302 (unless the lateral dimensions of the transducer are increased).

[0062] There figure 8 and the figure 9 illustrate the intermediate device obtained after attaching an interconnect layer 702 to the first major surface metal layer 204. The interconnect layer 702 is preferably a printed circuit board, and may be a flexible printed circuit board, a rigid printed circuit board, or a rigid-flexible printed circuit board. Rigid-flexible printed circuit boards are boards using a combination of rigid and flexible board technologies in an application.

[0063] The interconnect layer 702 includes a substrate 704 (i.e., a support layer) that is made of an electrically insulating material. For simplicity and clarity, the substrate 704 is shown as clear or transparent, but those skilled in the art will understand that the substrate 704 may also be translucent or opaque.

[0064] The interconnect layer 702 also includes a first set of conductive traces 706, 710, 714, 718, 722 and a third set of conductive traces 708, 712, 716, 720 on an inner surface 723 of the substrate 704. The inner surface 723 of the substrate 704 is directed toward the first major surface metal layer 204 on the metallized active material plate 302. Each trace of the first set of conductive traces 706, 710, 714, 718, 722 is in electrical communication with a respective column electrode contact of the first outer row of column electrode contacts 644, 648, 652, 656, 660. Each trace of the third set of conductive traces 708, 712, 716, 720 is in electrical communication with a respective column electrode contact of the second outer row of column electrode contacts 664, 670, 674, 678. The figure 8 illustrates a connection of the first set of conductive traces 706, 710, 714, 718, 722 and the third set of conductive traces 708, 712, 716, 720 with respective contacts of both the first outer row of column electrode contacts 644, 648, 652, 656, 660 and the second outer row of column electrode contacts 664, 670, 674, 678 which are in electrical communication with respective column electrodes of the set of column electrodes at the interface of the second main surface metal layer 206 and the acoustic impedance matching layer 402. However, it will be noted that all connections could be made of either the first outer row of column electrode contacts 644, 646, 648, 650, 652, 654, 656, 658, 660 (see figure 7 ), or the second external row of column electrode contacts 662, 664, 668, 670, 672, 674, 676, 678, 680 (see figure 7 ) and still be in electrical communication with respective column electrodes of the column electrode assembly at the interface of the second main surface metal layer 206 and the acoustic impedance matching layer 402.

[0065] The first set of conductive tracks 706, 710, 714, 718, 722 forms a first distribution of interconnections of the interconnection layer 702, and the third set of conductive tracks 708, 712, 716, 720 forms a third distribution of interconnections of the interconnection layer 702. Advantageously, the alternation of the tracks from the first set of conductive tracks 706, 710, 714, 718, 722 and the third set of conductive tracks 708, 712, 716, 720 allows for a larger spacing between the conductive tracks because the pitch between the conductive tracks is twice the pitch of the columns of the transducer.However, as previously described, the electrical connections with the column electrode assembly at the interface of the second main surface metal layer 206 and the acoustic impedance matching layer 402 could be formed on a same side of the metallized active material plate 302 (i.e., a non-interdigitated configuration) in a single distribution of the interconnection layer (i.e., a "first single set" of conductive traces including the first set of conductive traces 706, 710, 714, 718, 722 and the third set of conductive traces 708, 712, 716, 720).

[0066] The interconnect layer 702 also includes a second set of conductive traces 724, 728, 732, 736, 740 and a fourth set of conductive traces 726, 730, 734, 738, 742 on the inner surface 723 of the substrate 704. Each trace of the second set of conductive traces 724, 728, 732, 736, 740 and the fourth set of conductive traces 726, 730, 734, 738, 742 is in electrical communication with a respective one of the row electrode lines 624, 626, 628, 630, 632, 634, 636, 638, 640, 642.

[0067] The second set of conductive tracks 724, 728, 732, 736, 740 forms a second distribution of interconnections of the interconnection layer 702, and the fourth set of conductive tracks 726, 730, 734, 738, 742 forms a fourth distribution of interconnections of the interconnection layer 702. Advantageously, the alternation of the tracks from the second set of conductive tracks 724, 728, 732, 736, 740 and the fourth set of conductive tracks 726, 730, 734, 738, 742 forms an interdigitated configuration of the lines and allows for greater spacing between the conductive tracks because the pitch between the conductive tracks is twice the pitch of the lines of the transducer.However, it will be noted that the electrical connections with the row electrode lines 624, 626, 628, 630, 632, 634, 636, 638, 640, 642 could be formed on the same side of the metallized active material plate 302 (i.e., a non-interdigitated configuration) in a single distribution of the interconnect layer (i.e., a "second single set" of conductive traces including the second set of conductive traces 724, 728, 732, 736, 740 and the fourth set of conductive traces 726, 730, 734, 738, 742).

[0068] Therefore, all interconnections of the row and column elements of the row-column addressing ultrasonic transducer device are made on the first side 723 of the substrate 704 without the need for vias or folding of said substrate. However, it will be noted that one or both of the first set of conductive traces 706, 710, 714, 718, 722 and the third set of conductive traces 708, 712, 716, 720 could be on an outer surface of the substrate 704 and connected to respective contacts of the first outer row of column electrode contacts 644, 646, 648, 650, 652, 654, 656, 658, 660 (see figure 7 ), or the second external row of column electrode contacts 662, 664, 668, 670, 672, 674, 676, 678, 680 (see figure 7 ) using vias, as will be described later.

[0069] In some embodiments, each track of the first set of conductive tracks 706, 708, 710, 712, 714, 716, 718, 720, 722 and the second set of conductive tracks 724, 726, 728, 730, 732, 734, 736, 738, 740, 742 are in electrical contact with the first outer row of column electrode contacts 644, 648, 652, 656, 660, with the second outer row of column electrode contacts 664, 670, 674, 678, and with the row electrodes 624, 626, 628, 630, 632, 634, 636, 638, respectively. 640, 642, for example by means of a bonding material, for example a conductive glue or adhesive, or by means of a conductive anisotropic film.

[0070] There figure 10 illustrates an assembled RCA ultrasonic transduction device comprising the metallized active material plate 302, the acoustic impedance matching layer 402, and the interconnect layer 702, as previously described, and a backside layer assembly 902 attached to the interconnect layer 702. Attachment of the backside layer assembly 902 to the interconnect layer 702 is preferably performed by adhesive bonding by depositing an adhesive therebetween and a heat treatment polymerization process (ranging from room temperature to 100°C) and under applied pressure of the stack.

[0071] In one embodiment, the backside layers 902 are passive materials having acoustic damping or absorption properties such as an epoxy resin, either as a solid material or comprising absorbent fillers or air bubbles. In another embodiment, the backside layers comprise an integrated circuit intended to compactly integrate the transduction device with its driver circuit. In this case, one or more layers serving as an acoustic mirror (or "dematching layer") are interposed between the integrated circuit and the rest of the transduction device in order to prevent the integrated circuit from causing parasitic reflections of the ultrasonic wave towards the transducer.Advantageously, the layers forming the acoustic mirror are conductive, the main internal face comes into direct electrical contact with the electrodes of the RCA transduction device without recourse to the interconnection layer 702, the main external face is in contact with electrical pads on the integrated circuit.

[0072] There figure 11 and the figure 12 illustrate an alternative embodiment, similar to the embodiment illustrated in figure 7 and in figure 8 , of an intermediate assembly after cutting a metallized active material plate 102 to create saw cuts, wherein the saw cuts are filled with, for example, a polymeric material 1004 before attaching an interconnect layer 1006. The polymeric material provides mechanical decoupling between the transducer elements and may include fillers or air bubbles.

[0073] There figure 13 represents another alternative embodiment, in which the interconnection layer 1202 comprises an insulating substrate 1203 provided with interconnection distributions on the two main faces of the insulating substrate 1203. The interconnection distribution of the second set of conductive tracks 724, 726, 728, 730, 732, 734, 736, 738, 740, 742 of the interconnection layer 702 is unchanged in the case of the interconnection layer 1202.The interconnection layer 1202 is provided with a first set of electrical contact pads 1204, 1206, 1208, 1210, 1212, 1214, located on the inner main face of the insulating substrate 1203, and in respective electrical contact among a first outer row of column electrode contacts 1254, 1256, 1258, 1260, 1262, 1264; and a second set of electrical contact pads 1216, 1218, 1220, 1222, 1224, 1226 located on the inner main face of the insulating substrate 1203, and in respective electrical contact with a second outer row of column electrode contacts 1266, 1268, 1270, 1272, 1274, 1276.Vias, i.e. vertical electrical connections passing through the insulating substrate 1203, respectively connect a first set of electrical contact pads 1204, 1206, 1208, 1210, 1212, 1214, to a first set of conductive tracks 1228, 1230, 1232, 1234, 1236, 1238; and a second set of electrical contact pads 1216, 1218, 1220, 1222, 1224, 1226 respectively to a second set of conductive tracks 1240, 1242, 1244, 1246, 1248, 1250. This embodiment is particularly advantageous in that it makes it possible to double the number of conductive tracks per unit area of the interconnection layer 1202. The set of electrical interconnection tracks 1234, 1236, 1236, 1246, 1248, 1250, forms a first distribution of electrical interconnections on a first lateral face of the RCA transduction device.Similarly, the set of electrical interconnection tracks 1228, 1230, 1232, 1240, 1242, 1242, forms a second distribution of electrical interconnections on a second lateral face of the RCA transduction device opposite the first lateral face. In an alternative implementation, the first and second distribution of electrical interconnections exit through the same lateral face of the RCA transduction device. However, it will be further noted that if the electrical connections with the set of column electrodes are formed on the same lateral surface of the metallized active material plate 302, and the electrical connections with the row electrode lines are formed on the same lateral surface of the metallized active material plate 302, then the number of distributions can be reduced to one by placing the respective conductive tracks on opposite sides of the substrate 1203 and using vias and connection pads.

[0074] THE figures 14, 15 And 16 illustrate an alternative embodiment using metallized vias 1301 vertically passing through the active material plate 102 and electrically connecting the column electrodes covering the lower face 106 of the active material plate 102 (formed in the lower face metal layer 206), to the upper face metal layer 204.

[0075] The metallized vias 1301 are for example arranged at the ends of the columns of the ultrasonic transducer. For example, each column comprises two metallized vias 1301 arranged respectively at the two ends of the column. For example, each column may comprise a single metallized via arranged at one end of the column. Alternatively, each column may comprise more than two metallized vias 1301.

[0076] In this example, the metallized vias 1301 functionally replace the column electrode connectors 518, 520, 522, 524, 526, 528, 530, 532, 534, and the column electrode connectors 538, 540, 542, 544, 546, 548, 550, 552, 554, which electrically connect the column electrodes to the first major surface metal layer 204.

[0077] Thus, in this example, the side faces of the active material plate 102 at the ends of the columns may be non-metallized.

[0078] The process of forming the transducer is similar to what was previously described in relation to the figures 2 à 13 . Only the differences from the processes of the figures 2 à 13 are detailed below.

[0079] The process of figures 14, 15 And 16 differs from the examples described in relation to the figures 2 à 13 in that, in the example of figures 14, 15 And 16, through openings, for example cylindrical, are formed in the raw active material plate 102 at the desired locations of the vias 1301 of the future RCA ultrasonic transducer.

[0080] The openings are for example formed by photolithography and etching, or by any other suitable method of forming through openings in a raw active material plate.

[0081] A wrap-around metallization is then formed to obtain a metallized raw active material plate 202, similarly to what has been previously described in connection with the figure 3 . In this step, the through openings are filled with metal or have their sides coated with metal, forming the metallized vias 1301.

[0082] There figure 14 is a perspective view of the raw metallized active material plate 202 obtained at the end of this step. In this figure, the metallized vias 1301 are shown in transparency for illustration purposes.

[0083] The raw metallized active material plate 202 is then cut to individualize a metallized active material plate 302 with the desired dimensions of the ultrasonic transducer, in a manner similar to that described above in relation to the figure 4 .

[0084] There figure 15 is a perspective view schematically illustrating the metallized active material plate 302 obtained at the end of the cutting step.

[0085] Note that in this example, the dimensions of the metallized active material plate 302 may be smaller than the dimensions of the metallized raw active material plate 202. In particular, the width Wa of the metallized active material plate 302 may be smaller than the width Wp of the metallized raw active material plate 202, and the length La of the metallized active material plate 302 may be smaller than the length Lp of the metallized raw active material plate 202. In this case, none of the side faces of the plate 302 is metallized. In other words, the side surfaces of the active material plate 303 are all exposed, as illustrated in figure 15 .

[0086] The following steps of the method are for example identical or similar to what has been described previously in relation to the figures 5 , 6 , 7 , 8 , 9 , 10 , and, possibly, 11, 12 and / or 13.

[0087] There figure 16 illustrates the structure obtained at an intermediate stage of the process, corresponding to the structure obtained at the end of the steps described in relation to the figures 5 , 6 And 7 .

[0088] An advantage of the embodiment described in connection with the figures 14, 15 And 16 is that it allows the formation of transducers whose lateral dimensions are smaller than those of the raw plate, i.e. several active plates can be cut in both lateral directions. In this case, the lateral sides of the active plate are no longer metallized to form a wrapper as described in the examples of figures 2 à 13 The function of electrical connection of the column electrodes located on the lower face side of the active plate to metallizations located on the upper face side of the active plate is then ensured by the metallized vias 1301.

[0089] It will be understood that various details of the subject matter described herein may be modified without departing from the scope of the subject matter described and claimed herein. Furthermore, the foregoing description is for the purpose of illustration only and not limitation. For example, the numbers of rows and columns of the illustrated ultrasonic array (RCA) transducers have been simplified for illustration, whereas actual ultrasonic transducers may have many more elements in each direction, e.g., 64, 128, 256, or more transducer elements in each of the row and column directions.

Claims

1. Row-column addressing array ultrasound transduction device, comprising: - a metallized plate of active material (302) comprising a plate of active material (303) having a first main surface (104) and a second main surface (106) opposite to the first main surface, a first metallic main surface layer (204) on the first main surface (104), and a second metallic main surface layer (206) on the second main surface (106); - an acoustic impedance matching layer (402, 404) bonded to the second metallic main surface layer (206); - a first set of parallel cutting notches (502, 504, 506, 508, 510, 512, 514, 516) oriented in a first direction, said notches of the first set extending across the entire thickness of the metallized plate of active material (302) and along the entire length of the metallized plate of active material (302) in the first direction, and individualizing the second metallic main surface layer (206) into a set of column electrodes; - a second set of parallel cutting notches (602, 604, 606, 608, 610, 612, 614, 616, 618, 620, 622) oriented along a second direction different from the first direction, said notches of second set extending across the entire thickness of the first metallic main surface layer (204) and across at least part of the thickness of the plate of active material (303), and along the entire length of the metallized plate of active material (302) in the second direction, and individualizing the first metallic main surface layer (204) into a set of rows of row electrodes (624, 626, 628, 630, 632, 634, 636, 638, 640, 642) and a first external row of column electrode contacts (644, 646, 648, 650, 652, 654, 656, 658, 660), each column electrode contact of the first external row of column electrode contacts being electrically connected to a respective column electrode of the set of column electrodes; and - an interconnection layer (702) comprising a substrate (704) of an electrically-insulating material, a first set of conductive tracks (706, 710, 714, 716, 718, 722) on the substrate (704), each track of the first set of conductive tracks being in electrical contact with a respective column electrode contact (644, 648, 652, 656, 660) of the first external row of column electrode contacts, and a second set of conductive tracks (724, 726, 728, 730, 732, 734, 736, 738, 740, 742) on the substrate (704), each track of the second set of conductive tracks being in electrical communication with a respective row among the rows of row electrodes (624, 626, 628, 630, 632, 634, 636, 638, 640, 642) .

2. Device according to claim 1, wherein each column electrode contact (644, 646, 648, 650, 652, 654, 656, 658, 660) of the first external row of column electrode contacts is electrically connected to the respective corresponding column electrode of the set of column electrodes by a respective column electrode connector of a first set of column electrode connectors (518, 520, 522, 524, 526, 528, 530, 532, 534) formed in a first lateral surface metal layer (208) covering a first lateral surface of the plate of active material (303), the column electrode connectors of the first set of column electrode connectors being individualized by the cutting notches of the first set of cutting notches.

3. Device according to claim 1, wherein each column electrode contact (644, 646, 648, 650, 652, 654, 656, 658, 660) of the first external row of column electrode contacts is electrically connected to the respective corresponding column electrode of the set of column electrodes by a metallized via (1301) vertically crossing the plate of active material (303).

4. Device according to any of claims 1 to 3, wherein the substrate (704) of the interconnection layer (702) comprises an inner surface, wherein the first set of conductive tracks (706, 708, 710, 712, 714, 716, 718, 720, 722) and the second set of conductive tracks (724, 726, 728, 730, 732, 734, 736, 738, 740, 742) are on the inner surface of the substrate (704), and wherein the first set of conductive tracks forms a first interconnect fan-out of the interconnection layer, and the second set of conductive tracks (724, 726, 728, 730, 732, 734, 736, 738, 740, 742) forms a second interconnect fan-out of the interconnection layer.

5. Device according to any of claims 1 to 3, wherein the substrate (704) of the interconnection layer (702) comprises an inner surface, an outer surface, vias respectively aligned with the first external row of column electrode contacts, and respective via connectors (1204, 1206, 1208, 1210, 1212, 1214, 1216, 1218, 1220, 1222, 1224, 1226) in the vias; wherein the first set of conductive tracks is on the outer surface of the substrate (704) and is in electrical communication with respective column electrode contacts of the first external row of column electrode contacts by means of via connectors, and the second set of conductive tracks is on the inner surface of the substrate (704); and wherein the first set of conductive tracks and the second set of conductive tracks form a first interconnect fan-out of the interconnection layer.

6. Device according to any of claims 1 to 5, wherein the second set of parallel cutting notches (602, 604, 606, 608, 610, 612, 614, 616, 618, 620, 622) further individualizes a second external row of column electrode contacts (662, 668, 670, 672, 674, 676, 678, 680), each column electrode contact of the first external row of column electrode contacts being electrically connected to a respective column electrode of the set of column electrodes.

7. Device according to any of claims 1 to 6, wherein the first and second directions are orthogonal.

8. Device according to any of claims 1 to 7, wherein the first set of cutting notches and the second set of cutting notches are filled with a polymer material (1004).

9. Device according to any of claims 1 to 8, wherein the interconnection layer (702) is a flex printed circuit board.

10. Device according to any of claims 1 to 9, further comprising a set of backing layers (902) bonded to the interconnection layer (702).

11. Method of manufacturing a row-column addressing array ultrasound transduction device, the method comprising: the provision of a metallized raw plate of active material (202) comprising a plate of active material (103) having a first main surface (104) and a second main surface (106) opposite to the first main surface, a first metallic main surface layer (204) on the first main surface (104), and a second metallic main surface layer (206) on the second main surface (106), the metallized raw plate of active material having a width Wp and a length Lp; the cutting of the metallized raw plate of active material (202) to individualize a metallized plate of active material (302) from the metallized raw plate of active material (202); the bonding of an acoustic impedance matching layer to the second metallic main surface layer (206) of the metallized plate of active material (302); the full cutting of the metallized plate of active material (302) in a first direction to form a first set of parallel cutting notches, the first set of cutting notches forming in the second metallic main surface layer (206) a set of column electrodes; the partial cutting of the metallized plate of active material (302) in a second direction to form a second set of parallel cutting notches, the second set of cutting notches forming in the first metallic main surface layer (204) rows of row electrodes and a first external row of column electrode contacts, each column electrode contact of the first external row of column electrode contacts being electrically connected to a respective column electrode of the set of column electrodes; the provision of an interconnection layer (702) comprising a substrate (704) of an electrically-insulating material, a first set of conductive tracks on the electrically-insulating substrate (704), a second set of conductive tracks on the electrically-insulating substrate (704); the connection of each track of the first set of conductive tracks so that it is in electrical communication with a respective column electrode contact of the first external row of column electrode contacts; and the connection of each track of the second set of conductive tracks in electrical contact with a respective row among the rows of row electrodes.

12. Method according to claim 11, wherein each column electrode contact (644, 646, 648, 650, 652, 654, 656, 658, 660) of the first external row of column electrode contacts is electrically connected to the respective corresponding column electrode of the set of column electrodes by a respective column electrode connector of a first set of column electrode connectors (518, 520, 522, 524, 526, 528, 530, 532, 534) formed in a first lateral surface metal layer (208) of the metallized plate of active material (302), covering a first lateral surface of the plate of active material (303), the column electrode connectors of the first set of column electrode connectors being individualized by the cutting notches of the first set of cutting notches.

13. Method according to claim 12, wherein the metallized plate of active material (302) has a length La smaller than the length Lp of the metallized raw plate of active material (202) and a width Wa equal to the width Wp of the metallized raw plate of active material (202).

14. Method according to claim 11, wherein each column electrode contact (644, 646, 648, 650, 652, 654, 656, 658, 660) of the first external row of column electrode contacts is electrically connected to the respective corresponding column electrode of the set of column electrodes by a metallized via (1301) of the metallized plate of active material (302), vertically crossing the plate of active material (303).

15. Method according to claim 14, wherein the metallized plate of active material (302) has a length La smaller than the length Lp of the metallized raw plate of active material (202) and a width Wa smaller than the width Wp of the metallized raw plate of active material (202)