Phased array focused ultrasound transducer and method of manufacturing the same

Abstract

The application relates to a phased array focusing ultrasonic transducer and a manufacturing method thereof, and relates to the field of focusing ultrasonic technology. The phased array focusing ultrasonic transducer comprises a spherical piezoelectric ceramic substrate, a front common electrode, a back sub-array electrode and an electrode leading-out assembly; the back surface of the spherical piezoelectric ceramic substrate is semi-translucently cut along a concentric circular track to form a ring-shaped first array element; the front surface of the spherical piezoelectric ceramic substrate is entirely plated with a metal electrode layer to form the front common electrode; the surface of each first array element on the back surface of the spherical piezoelectric ceramic substrate is independently plated with a metal electrode to form the back sub-array electrode; and the electrode leading-out assembly is welded on the side surface of the front common electrode. The application adopts a whole substrate semi-translucent cutting process, does not need to bond discrete array elements one by one, and directly guarantees the concentricity and size precision of the array elements by a cutting device, thereby completely avoiding positioning errors caused by manual splicing; the cutting groove does not need to be filled with adhesive, thereby eliminating the damping influence of the adhesive layer on the vibration of the array element, and meanwhile, the adhesive filling and curing process is omitted, and the manufacturing efficiency is improved by more than 50%.

Description

Technical Field

[0001] This invention relates to the field of focused ultrasound technology, specifically to a phased array focused ultrasound transducer and its manufacturing method. Background Technology

[0002] Phased array focused ultrasound technology can achieve electronic scanning and depth adjustment of the focal point by adjusting the emission phase of different array elements. It can complete precise energy deposition without mechanical movement. In recent years, it has played an irreplaceable role in high-end biomedical fields such as brain-computer interface neuromodulation, thermal ablation of solid tumors, and targeted drug delivery, as well as industrial fields such as non-destructive testing of pipes and precision material processing.

[0003] Among them, the ring-spherical array transducer has become the mainstream technology for medium-depth focused ultrasound applications due to its advantages such as axisymmetric sound field distribution, strong axial focusing capability, high energy utilization, and a significantly fewer number of drive channels required than a planar array. Existing ring-spherical phased array transducers mainly have two fabrication schemes, both of which have significant technical drawbacks: 1. Discrete array element bonding scheme This scheme involves splicing multiple concentric spherical piezoelectric ceramic array elements of equal area one by one, filling the gaps between the array elements with adhesive to achieve fixation and sealing, and attaching a matching layer material to the front of the array. At the same time, the matching layer helps to fix the array elements and plays a role in acoustic impedance matching and appearance protection.

[0004] Its core flaws include: (1) Assembly is difficult and the precision is low: the spherical ring array element has a large arc and small size. It is difficult to ensure concentricity and gap consistency when splicing manually or with tooling. The positioning error directly affects the focusing accuracy. (2) Acoustic performance degradation: The adhesive in the gap between array elements will form a damping layer, which will interfere with the thickness vibration mode of the array elements, reduce the electromechanical conversion efficiency, and introduce additional clutter. (3) The front parallel connection process is complicated: all array elements need to be connected in parallel with the common ground on the front side. Additional wires or conductive glue need to be welded to connect them. The solder joints and wires will destroy the flatness of the sound output surface, causing sound field scattering distortion. Moreover, the welding process is cumbersome and has poor reliability.

[0005] 2. Overall cutting wide ring solution

[0006] To address the positioning issue, some processes first bond a single spherical ceramic sheet to the matching layer, then cut out several wide annular array elements of equal area from the back. While this approach ensures the concentricity of the array elements, it still has inherent drawbacks: (1) Poor vibration performance: The radial width of the equal-area wide ring array element is large, which easily excites stray vibration modes such as radial bending and planar stretching, which couple with the thickness stretching vibration required for operation, resulting in resonance peak splitting, electromechanical efficiency reduction and sidelobe lifting of the focused sound field; (2) Poor impedance consistency: The radial width of the inner and outer array elements differs greatly, the uniformity of piezoelectric material parameters and the high dispersion of electrode parasitic parameters result in significant differences in impedance of each array element. The back-end drive system needs to design a matching network for each channel, which makes the system complex and debugging and calibration cumbersome. (3) Difficulty in parallel connection of front electrodes: After cutting, the front electrodes are disconnected from the ceramic substrate. If the front electrodes are to be grounded, they need to be rewired from the front or welded across the slot, which is difficult and can easily damage the array elements.

[0007] In summary, existing ring-shaped spherical phased array transducers have consistently failed to simultaneously achieve ease of manufacturing, uniformity of array element impedance, and excellent acoustic performance, becoming the core bottleneck restricting their large-scale application. Summary of the Invention

[0008] To address at least one technical problem in the prior art, this invention provides a phased array focused ultrasonic transducer and its manufacturing method. It adopts a semi-transparent cutting process for an integral substrate, eliminating the need to bond discrete array elements one by one. The concentricity and dimensional accuracy of the array elements are directly guaranteed by the cutting equipment, completely avoiding the positioning errors of manual splicing. The cutting groove does not need to be filled with adhesive, eliminating the damping effect of the adhesive layer on the vibration of the array elements. At the same time, it eliminates the adhesive filling and curing process, improving manufacturing efficiency by more than 50%.

[0009] To achieve the above objectives, the present invention provides a phased array focused ultrasonic transducer, comprising: a spherical piezoelectric ceramic substrate, a front common electrode, a back sub-element electrode, and an electrode lead-out assembly; the back side of the spherical piezoelectric ceramic substrate is semi-through-cut along a concentric circular trajectory to form a plurality of annular first elements; the entire front side of the spherical piezoelectric ceramic substrate is plated with a metal electrode layer to form the front common electrode; each first element on the back side of the spherical piezoelectric ceramic substrate is independently plated with a metal electrode to form a back sub-element electrode; the electrode lead-out assembly is welded to the side of the front common electrode.

[0010] Furthermore, the depth of the semi-permeable cut is less than the total thickness of the substrate, and the piezoelectric substrate on the front side of the substrate remains continuous and intact, without being penetrated by the cut groove. This allows for the mechanical connection and precise positioning of all subarray elements without the need for adhesive filling.

[0011] Furthermore, several first array elements are grouped according to preset rules, and all back-side sub-array elements in the same group are electrically connected in parallel to form a second array element.

[0012] Furthermore, the electrode lead-out assembly includes several conductive sheets, which are evenly distributed along the edge of the substrate in a rotationally symmetrical manner; one end of the conductive sheet is welded to the side connected to the front common electrode, and the other end is bent along the side wall of the substrate and extends to the back side, so as to realize the low distortion lead-out of the front common electrode to the back side.

[0013] Furthermore, it also includes a plastic housing, with the front edge of the spherical piezoelectric ceramic substrate contacting the boss inside the housing. There is a sealing ring on the side and front edge of the spherical piezoelectric ceramic substrate, and another pressure ring fixes the spherical piezoelectric ceramic substrate to the boss of the housing by pressing the sealing ring on the convex edge. The coaxial signal line is led out from the side wall of the plastic housing, and the back cover is fixed to the plastic with bolts.

[0014] A method for manufacturing a phased array focused ultrasonic transducer, characterized by comprising the following steps; Step S1: Prepare a one-piece spherical piezoelectric ceramic substrate; Step S2: Perform a semi-through cut from the back of the spherical piezoelectric ceramic substrate, aligning it with the concentric ring trajectory. Control the cutting depth to 60%~95% of the total thickness of the spherical piezoelectric ceramic substrate, while retaining the continuous piezoelectric ceramic substrate on the front side, forming several ring-shaped first elements. Step S3: Group the first array elements on the back side and connect them in parallel. Electrically connect the back electrodes of the first array elements in the same group to form multiple second array elements with the same effective area. Step S4: On the side or front of the spherical piezoelectric ceramic substrate, several conductive sheets are circumferentially rotated and symmetrically welded. The conductive sheets are then smoothly bent along the side wall of the spherical piezoelectric ceramic substrate to the back side to complete the back lead-out of the front common electrode. Step S5: Solder the signal leads and common electrode leads of each second array element on the back side, and attach the matching layer and backing material as required to complete the transducer encapsulation.

[0015] The beneficial effects of this invention are as follows: 1. Significantly simplified process, comprehensively improved assembly precision and reliability: Utilizing a semi-transparent cutting process for the entire substrate eliminates the need for individual bonding of discrete array elements. The concentricity and dimensional accuracy of the elements are directly guaranteed by the cutting equipment, completely avoiding positioning errors inherent in manual assembly. The cutting grooves do not require adhesive filling, eliminating the damping effect of the adhesive layer on element vibration and eliminating the need for the adhesive filling and curing process, thus increasing manufacturing efficiency by over 50%. The naturally continuous front substrate allows for parallel connection of all array elements without additional wire welding to the front electrodes, resolving the pain points of complex front parallel connection processes and poor reliability in traditional solutions. Furthermore, it eliminates the need to rely on a matching layer to fix the array elements; the matching layer can be designed independently as an acoustic functional layer.

[0016] 2. Highly consistent array element impedance significantly reduces system complexity: The dispersion of the single-loop geometric parameters, piezoelectric material uniformity, and electrode parasitic parameters of the first array element is extremely low. By adjusting the number of sub-array elements in each group, the effective radiation area of ​​the second array element can be precisely controlled, ensuring high consistency in the static capacitance and acoustic impedance of each working array element. The back-end drive system can use a unified matching network, eliminating the need for individual design and calibration for each channel, significantly reducing system hardware costs and debugging workload.

[0017] 3. Pure vibration modes, with improved electromechanical conversion efficiency and focusing performance: The first element of the fine-ring structure can push the resonant frequency of radial stray vibration away from the working frequency band, effectively suppressing stray mode coupling and ensuring that the element operates in a pure thickness stretching vibration mode, significantly improving the electromechanical coupling coefficient and acoustic output power. At the same time, the in-plane vibration phase uniformity of the fine-ring element is better, the main lobe of the focused sound field is narrower and the side lobes are lower, the focal energy concentration is higher, and the treatment or detection accuracy is better.

[0018] 4. Optimized electrode lead-out scheme, resulting in less acoustic field distortion and higher reliability: The front common electrode is led out using a rotationally symmetrically distributed conductive sheet. Compared to traditional multi-wire welding schemes, this results in a larger conductive cross-sectional area, lower contact resistance, and more uniform circumferential power supply, ensuring the uniformity of the axisymmetric acoustic field. The thickness of the conductive sheet is typically controlled within 50μm, minimizing acoustic field disturbance and scattering at the sound output surface and avoiding acoustic field distortion caused by thick wires. Furthermore, the sheet-like welding provides a larger contact area and higher mechanical strength, resulting in significantly better long-term reliability than wire spot welding. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a front view of the spherical piezoelectric ceramic substrate of the present invention; Figure 3 This is a top view of the spherical piezoelectric ceramic substrate of the present invention; Figure 4 This is a schematic diagram of the structure of the present invention with a plastic outer shell.

[0020] In the figure: 1-Spherical piezoelectric ceramic substrate; 2-Conductive sheet; 3-Plastic shell; 4-Sealing ring. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0024] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0025] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0026] To address the shortcomings of existing technologies, this invention aims to solve the following technical problems: reduce the manufacturing and assembly difficulty of the ring-shaped spherical phased array transducer, improve the positioning accuracy of array elements, and eliminate the negative impact of the gap bonding layer on vibration performance; significantly improve the impedance consistency of each working array element, simplify the matching network design and debugging process of the back-end drive system; optimize the vibration mode of the array elements, suppress stray modes, and improve the electromechanical conversion efficiency and focused sound field quality of the transducer; and achieve low sound field interference and high reliability of the front common electrode lead-out, solving the pain point of complex front parallel connection process in traditional solutions.

[0027] refer to Figures 1 to 4This invention provides a phased array focused ultrasound transducer, comprising: a spherical piezoelectric ceramic substrate 1, a front common electrode, a back sub-element electrode, and an electrode lead-out assembly; the back of the spherical piezoelectric ceramic substrate 1 is semi-through-cut along a concentric circular trajectory to form several annular first elements; the entire front surface of the spherical piezoelectric ceramic substrate 1 is plated with a metal electrode layer to form a front common electrode. Because the front substrate is continuous and uncut, this electrode naturally becomes the common front electrode shared by all the first elements, achieving electrical parallel connection of all elements on the front without additional welding of conductive materials; each first element on the back surface of the spherical piezoelectric ceramic substrate 1 is independently plated with a metal electrode to form a back sub-element electrode; the electrode lead-out assembly is welded to the side of the front common electrode.

[0028] Further optimizing the technical solution, the depth of the semi-permeable cut is less than the total thickness of the substrate. The piezoelectric matrix on the front (concave) side of the substrate remains continuous and intact, and is not penetrated by the cut groove. Mechanical connection and precise positioning of all sub-array elements can be achieved without filling adhesive.

[0029] The concentricity and dimensional accuracy of the first array element are directly guaranteed by the cutting equipment, completely avoiding positioning errors caused by manual or tooling splicing in traditional discrete array element bonding schemes, ensuring focusing accuracy. The cutting groove does not require adhesive filling, avoiding the damping interference of adhesive on the thickness vibration mode of the first array element, improving electromechanical conversion efficiency, and eliminating additional noise introduced by the adhesive layer. Eliminating the adhesive filling and curing process increases manufacturing efficiency by more than 50%; the front substrate is naturally continuous, and the front electrodes can achieve parallel connection of all array elements without additional welding wires, solving the pain points of complex and unreliable front parallel connection processes. There is no need to rely on a matching layer to fix the array elements; the matching layer can be independently optimized as an acoustic functional layer.

[0030] The fine-ring structure of the first array element pushes the resonant frequencies of stray vibration modes such as radial bending and planar stretching away from the operating frequency band, effectively suppressing the coupling between stray modes and the required thickness stretching vibrations, ensuring that the array element operates in a pure thickness stretching mode, and significantly improving the electromechanical coupling coefficient and acoustic output power. The first array element has better in-plane vibration phase uniformity, a narrower main lobe and lower side lobes in the focused sound field, higher focal energy concentration, and better treatment or detection accuracy. The single-ring geometric parameters, piezoelectric material uniformity, and electrode parasitic parameters have extremely low dispersion, providing a highly consistent sub-array element basis for subsequent grouping and parallel connection.

[0031] To further optimize the technical solution, several first array elements are grouped according to preset rules, and all back-side sub-array elements in the same group are electrically connected in parallel to form a second array element (effective working array element). By controlling the number of sub-array elements in each group, the effective radiation area of ​​all second array elements is made to be completely equal, and finally a concentric spherical phased array composed of multiple second array elements is formed.

[0032] By precisely adjusting the number of sub-element elements in each group, the effective radiation area of ​​each second element is ensured to be completely equal, thereby achieving high consistency in the static capacitance and acoustic impedance of each element. The back-end drive system can use a unified matching network, eliminating the need for individual design and calibration for each channel, significantly reducing system hardware costs and debugging workload. Flexible grouping is possible according to requirements, adapting to application scenarios with different numbers of drive channels, balancing manufacturing convenience and system integration.

[0033] To further optimize the technical solution, the electrode lead-out assembly includes several conductive sheets 2 (such as thin copper strips or silver foils), which are evenly distributed along the edge of the substrate in a rotationally symmetrical manner. One end of the conductive sheet 2 is welded to the side (facade) connected to the front common electrode, and the other end is bent along the side wall of the substrate and extends to the back side, so as to realize the low distortion lead-out of the front common electrode to the back side.

[0034] The thickness of the conductive sheet is typically controlled within 50μm, resulting in minimal disturbance and scattering of the sound field at the sound output surface. This avoids the sound field distortion caused by traditional thick wire welding and ensures the uniformity of the axisymmetric sound field. The sheet-like contact area is large, with low contact resistance, resulting in more uniform circumferential power supply. The welding mechanical strength is high, and long-term reliability is significantly better than wire spot welding. No additional wires or conductive adhesive are required on the front side, and the back leads facilitate subsequent signal line soldering and encapsulation.

[0035] The invention also includes a plastic housing 3, the front edge of the spherical piezoelectric ceramic substrate 1 contacts the protrusion inside the housing, the spherical piezoelectric ceramic substrate 1 has a sealing ring 4 on both the side and front edge, and a pressure ring fixes the spherical piezoelectric ceramic substrate 1 to the protrusion of the housing by pressing the sealing ring 4 on the convex edge; the coaxial signal line is led out from the side wall of the plastic housing 3, and the back cover is fixed to the plastic with bolts, thereby completing the encapsulation of the spherical piezoelectric ceramic substrate 1.

[0036] The dual sealing rings provide excellent waterproof and dustproof sealing, while the clamping ring and boss cooperate to achieve a mechanically secure fixation, avoiding the stress or damping effects caused by the use of adhesives. The signal cable is led out from the side wall, and the rear cover is removable for easy assembly, testing, and maintenance, while the housing provides physical protection.

[0037] The present invention also provides a method for manufacturing a phased array focused ultrasonic transducer, comprising the following steps; Step S1: Prepare an integrally formed spherical piezoelectric ceramic substrate 1, the electrode structure of which includes at least a front electrode and a back electrode; Step S2: Using a precision cutting process, perform a semi-through cut from the back of the substrate, aligned with the concentric ring trajectory. The cutting depth is controlled to be 60%~95% of the total thickness of the substrate, while retaining the continuous piezoelectric ceramic substrate on the front side, forming several ring-shaped first elements. Step S3: Group the first array elements on the back side and connect them in parallel. Electrically connect the back electrodes of the first array elements in the same group by means of conductive silver paste bonding or wire bonding to form multiple second array elements with the same effective area. Step S4: On the side or front of the substrate, several thin conductive sheets 2 are circumferentially rotated and symmetrically welded. The conductive sheets 2 are then smoothly bent along the side wall of the substrate to the back side to complete the back lead-out of the front common electrode. Step S5: Solder the signal leads and common electrode leads of each second array element on the back side. A matching layer and backing material can be attached as needed to complete the transducer encapsulation.

[0038] This invention features a one-step cutting process, avoiding errors from multiple clamping operations. All electrical connections are completed on the back side, maintaining the integrity and continuity of the front side, ensuring the acoustic radiation surface is not damaged by welding or wiring. It eliminates the cumbersome processes of traditional solutions, such as individual element bonding, adhesive filling and curing, and front-side wiring. Furthermore, parallel grouping ensures element consistency, achieving a balance between efficient manufacturing and superior performance. The matching layer and backing material can be flexibly selected according to different application requirements (such as treatment and detection), offering strong process versatility.

[0039] Example

[0040] The invention will be further illustrated below with reference to an example of a 4-channel focused ultrasound transducer for non-invasive brain-computer interfaces: A method for manufacturing a phased array focused ultrasonic transducer is provided, comprising the following steps; (1) Cut 13 rings (circles) on the convex surface of a spherical piezoelectric ceramic substrate coated with electrodes. The cutting depth is about 70% of the thickness of the piezoelectric ceramic and the cutting width is <1mm. These 13 rings (circles) are the 13 first array elements.

[0041] (2) Divide the 13 first array elements into 4 groups from the inside out in a 6-3-2-2 combination. The width of the first array elements in the same group is equal (except for the small circle in the center). The first group contains 6 first array elements, the second group contains 3 first array elements, and the third and fourth groups each contain 2 first array elements. Connect the back electrodes of the first array elements in the same group in parallel by means of conductive silver adhesive strips or bonding wires to form 4 second array elements with completely equal effective radiation areas, corresponding to 4 independent driving channels; (3) The front common electrode is led out by 6 thin copper strips. The thin copper strips are symmetrically distributed along the circumference of the spherical piezoelectric ceramic substrate. One end is welded to the side of the spherical piezoelectric ceramic substrate, and the other end is bent along the side wall of the spherical piezoelectric ceramic substrate to the back side as the common ground electrode. (4) The four second array elements on the back are respectively welded with coaxial signal lines, and the thin copper strips led out from the front are uniformly welded with a common ground line.

[0042] (5) A plastic housing is selected. The concave edge of the spherical piezoelectric ceramic substrate contacts the protrusion inside the housing. There is a sealing ring on the side and convex edge of the spherical piezoelectric ceramic substrate. Another pressure ring fixes the spherical piezoelectric ceramic substrate to the protrusion of the housing by pressing the sealing ring on the convex edge. Four coaxial signal lines are led out from the side wall of the housing. The back cover is fixed to the housing with bolts to complete the encapsulation.

[0043] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A phased array focusing ultrasonic transducer, characterized in that, include: The spherical piezoelectric ceramic substrate comprises a front common electrode, a back sub-element electrode, and an electrode lead-out assembly. The back of the spherical piezoelectric ceramic substrate is semi-through-cut along a concentric circular trajectory to form several annular first elements. The front of the spherical piezoelectric ceramic substrate is plated with a metal electrode layer to form the front common electrode. Each first element on the back of the spherical piezoelectric ceramic substrate is independently plated with a metal electrode to form a back sub-element electrode. The electrode lead-out assembly is welded to the side of the front common electrode.

2. The phased array focused ultrasonic transducer as described in claim 1, characterized in that, The depth of the semi-permeable cut is less than the total thickness of the substrate. The piezoelectric substrate on the front side of the substrate remains continuous and intact, and is not penetrated by the cut groove. Mechanical connection and precise positioning of all subarray elements can be achieved without filling adhesive.

3. The phased array focusing ultrasonic transducer as described in claim 2, characterized in that, Several first array elements are grouped according to a preset rule, and the electrodes of all back-side sub-array elements in the same group are electrically connected in parallel to form a second array element.

4. A phased array focusing ultrasonic transducer as described in claim 3, characterized in that, The electrode lead-out assembly includes several conductive sheets, which are evenly distributed along the edge of the substrate in a rotationally symmetrical manner. One end of the conductive sheet is welded to the side connected to the front common electrode, and the other end is bent along the side wall of the substrate and extends to the back side, so as to realize the low distortion lead-out of the front common electrode to the back side.

5. A phased array focusing ultrasonic transducer as described in claim 4, characterized in that, It also includes a plastic housing, with the front edge of the spherical piezoelectric ceramic substrate in contact with the protrusion inside the housing. There is a sealing ring on the side and front edge of the spherical piezoelectric ceramic substrate, and a pressure ring to fix the spherical piezoelectric ceramic substrate to the protrusion of the housing by pressing the sealing ring on the convex edge. The coaxial signal line is led out from the side wall of the plastic housing, and the back cover is fixed to the plastic with bolts.

6. A method for manufacturing a phased array focused ultrasonic transducer as described in any one of claims 1-5, characterized in that, Includes the following steps; Step S1: Prepare a one-piece molded spherical piezoelectric ceramic sheet; Step S2: Perform a semi-through cut from the back of the spherical piezoelectric ceramic substrate, aligning it with the concentric ring trajectory. Control the cutting depth to 60%~95% of the total thickness of the spherical piezoelectric ceramic substrate, while retaining the continuous piezoelectric ceramic substrate on the front side, forming several ring-shaped first elements. Step S3: Group the first array elements on the back side and connect them in parallel. Electrically connect the back electrodes of the first array elements in the same group to form multiple second array elements with the same effective area. Step S4: On the side or front of the spherical piezoelectric ceramic substrate, several conductive sheets are circumferentially rotated and symmetrically welded. The conductive sheets are then smoothly bent along the side wall of the spherical piezoelectric ceramic substrate to the back side to complete the back lead-out of the front common electrode. Step S5: Solder the signal leads and common electrode leads of each second array element on the back side, and attach the matching layer and backing material as required to complete the transducer encapsulation.

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