An array ultrasonic transducer

Abstract

The application provides an array ultrasonic transducer, which comprises a sound absorption backing layer, a piezoelectric layer, an acoustic matching layer and an acoustic lens arranged in sequence; the piezoelectric layer comprises an array element signal lead area and a piezoelectric array element area on a plane; and the array ultrasonic transducer further comprises a flexible circuit board which is electrically connected to the array element signal lead area, so that the flexible circuit board is distributed on the periphery of the piezoelectric layer and is not between the piezoelectric array element and the sound absorption backing layer, thereby eliminating the influence of the flexible circuit board on the performance of the array ultrasonic transducer. In addition, the array element signal lead area and the piezoelectric array element area are on the same piezoelectric material, so that the difficulty and complexity of the process are avoided. Furthermore, the leads of the flexible circuit board correspond to the signal electrodes of each piezoelectric array element one by one, so that the electrical connection between the array element signal lead area and the flexible circuit board is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic transducers, and in particular to an array ultrasonic transducer. Background Art

[0002] Ultrasonic imaging is widely used in fields such as medical diagnosis and industrial testing, offering advantages such as being non-destructive, radiation-free, convenient, and low-cost. Ultrasonic transducers, devices that convert electrical excitation signals into ultrasonic signals and reflective ultrasonic signals into electrical signals, are key components of ultrasonic imaging equipment. Their performance directly determines the quality of ultrasonic imaging. Ultrasonic transducers are primarily categorized as single-element ultrasonic transducers and array ultrasonic transducers. Due to the ease of imaging provided by array ultrasonic transducers, they are currently the primary method used in ultrasonic imaging equipment in the medical and industrial fields.

[0003] Existing ultrasonic transducers and their preparation methods have different shortcomings that affect the performance of ultrasonic transducers:

[0004] When an ultrasonic transducer is operating, the vibration of the piezoelectric element simultaneously emits ultrasonic waves forward and backward. The forward direction refers to the matching layer, while the backward direction refers to the backing layer. Forward ultrasonic waves are required for ultrasonic imaging, but backward ultrasonic waves are not. These backward ultrasonic waves reflect and affect the forward ultrasonic waves, thereby affecting the quality of the ultrasonic image. Flexible printed circuit boards can simplify the wiring process of array ultrasonic transducers, but they are typically sandwiched between the piezoelectric array elements and the backing layer, which can degrade transducer performance.

[0005] Most ultrasonic transducers place a flexible circuit board between the piezoelectric array elements and the backing layer. While various manufacturing methods have been used to reduce the thickness of the flexible circuit board to mitigate its impact, this reduction in size is limited. Even with existing technologies, even with reduced thickness, the flexible circuit board still significantly impacts imaging quality, thereby reducing transducer performance.

[0006] To eliminate the influence of flexible circuit boards, some array ultrasonic transducers use a configuration in which the flexible circuit boards are placed on both sides of the piezoelectric array elements. However, this configuration makes the process of connecting the flexible circuit boards to the piezoelectric array elements complex and costly. For example, the connection between the flexible circuit board signal lines and the conductive electrodes of the piezoelectric array elements requires a series of process steps, including coating with a silicon dioxide-filled epoxy resin, laser ablation, gold plating, coating with a resist, wet etching, laser etching, and finally chemically dissolving the resist. In addition, the array elements of high-frequency ultrasonic transducers are relatively small, making the connection process between the flexible circuit board and the piezoelectric array elements difficult. Low-frequency ultrasonic transducers use welding or conductive adhesive to connect a single coaxial line to a single array element to save costs. However, the number of ultrasonic transducer array elements is relatively large, generally more than 128, and each array element must be connected individually, making the process complex and time-consuming, and the yield rate and reliability are low.

[0007] In summary, existing ultrasonic transducer manufacturing methods mostly involve inserting a flexible printed circuit board directly between the piezoelectric array element and the backing layer, which can reduce transducer performance. Some methods also place the flexible printed circuit board on either side of the piezoelectric array element, but the process of electrically connecting the flexible printed circuit board circuitry to the piezoelectric array element is very complex and costly. To save costs, some ultrasonic transducers use welding or conductive adhesive to connect a single coaxial line to a single array element. However, with a large number of transducer array elements, each element must be individually connected, making the process complex and time-consuming, and resulting in low yield and reliability. Summary of the Invention

[0008] In view of this, in order to overcome the above-mentioned defects of the prior art, the present invention proposes an array ultrasonic transducer that does not increase the complexity and difficulty of the process.

[0009] Specifically, the arrayed ultrasonic transducer includes a sound-absorbing backing layer, a piezoelectric layer, an acoustic matching layer, and an acoustic lens, which are sequentially arranged. The piezoelectric layer includes an array element signal lead region and a piezoelectric array element region. The transducer also includes a flexible circuit board, which is electrically connected to the array element signal lead region. Preferably, the array element signal lead region and the piezoelectric array element region are arranged on the same piece of piezoelectric material and can be integrally formed, thereby avoiding increasing the complexity and difficulty of the process. In some embodiments, the piezoelectric layer includes a piece of piezoelectric material, and the array element signal lead region and the piezoelectric array element region are respectively arranged on different areas of the piezoelectric material.

[0010] Furthermore, the piezoelectric layer includes a piezoelectric sheet, a ground electrode surface disposed on one surface of the sheet, and a signal electrode surface disposed on the other surface of the sheet. The piezoelectric layer is provided with grooves corresponding to the boundaries between the array element signal lead region and the piezoelectric element region; the flexible circuit board is connected to the signal electrode surface. The piezoelectric sheet includes multiple piezoelectric elements, each of which has a ground electrode located on the ground electrode surface and a signal electrode located on the signal electrode surface. The leads of the flexible circuit board correspond one-to-one with the signal electrodes of each piezoelectric element. Preferably, an insulating material, such as epoxy resin, is filled between the piezoelectric elements. The piezoelectric element dimensions and spacing between the piezoelectric element signal lead region and the piezoelectric element region are at least 90% similar.

[0011] In some embodiments, the piezoelectric array element region may be a one-dimensional array, preferably a one-dimensional linear array; the array element signal lead regions are distributed on one or both sides of the piezoelectric array element region; and the number of flexible circuit boards is 1-2. Alternatively, the piezoelectric array element region may be a two-dimensional planar array; the array element signal lead regions are distributed on any one to four sides of the piezoelectric array element region; and the number of flexible circuit boards is 1-4. The circuits of the flexible circuit board correspond one-to-one with the electrodes on the array element signal lead regions, facilitating connection between the array element signal lead regions and the flexible circuit board.

[0012] Specifically, when there is only one flexible circuit board, the flexible circuit board is provided with a hollow area, and the hollow area corresponds to the size of the piezoelectric array element area. In some embodiments, when there are two or more flexible circuit boards, the flexible circuit boards do not cover the piezoelectric array element area after being spliced.

[0013] Optionally, the flexible circuit board is arranged between the piezoelectric layer and the sound-absorbing backing layer, and the signal electrode surface faces the sound-absorbing backing layer; or, the flexible circuit board is arranged between the piezoelectric layer and the acoustic matching layer, or between the acoustic matching layer and the acoustic lens, and the signal electrode surface faces the acoustic matching layer.

[0014] In summary, the arrayed ultrasonic transducer of the present invention places the flexible circuit board on the periphery of the piezoelectric layer, rather than between the piezoelectric array element and the sound-absorbing backing layer, thereby eliminating the influence of the flexible circuit board on the arrayed ultrasonic transducer. Furthermore, the leads of the flexible circuit board correspond one-to-one with the signal electrodes of each piezoelectric array element, facilitating the electrical connection between the array element signal lead area and the flexible circuit board. Preferably, the array element signal lead area and the piezoelectric array element area are on the same piece of piezoelectric material and can be integrally formed, avoiding increasing the difficulty and complexity of the process. The arrayed ultrasonic transducer provided by the present invention has a high yield rate, strong reliability, a simple preparation process, and strong operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1a Schematic diagram of the internal structure of the array ultrasonic transducer of the present invention;

[0017] Figure 1b is another schematic diagram of the internal structure of the array ultrasonic transducer of the present invention;

[0018] Figure 2a Schematic diagram of the structure of the piezoelectric layer of the array ultrasonic transducer of the present invention;

[0019] Figure 2b A schematic structural diagram of the piezoelectric layer of the array ultrasonic transducer of the present invention from another angle;

[0020] Figure 2c This is a schematic diagram of the ground electrode surface structure of the piezoelectric layer of the array ultrasonic transducer of the present invention;

[0021] Figure 2d Schematic diagram of the structure of the signal electrode surface of the piezoelectric layer of the array ultrasonic transducer of the present invention;

[0022] Figure 3a This is a schematic diagram of the structure in which the lead array element area is distributed on one side of the piezoelectric array element area;

[0023] Figure 3b This is a schematic diagram of the structure in which the lead array element area is distributed on both sides of the piezoelectric array element area;

[0024] Figure 3c is a schematic diagram of another structure in which the lead array element area is distributed on both sides of the piezoelectric array element area;

[0025] Figure 4a This is a schematic diagram of the structure in which the lead array element area is distributed on the four sides of the piezoelectric array element area;

[0026] Figure 4b This is another structural diagram in which the lead array element area is distributed on four sides of the piezoelectric array element area;

[0027] Figure 4c This is another structural diagram in which the lead array element area is distributed on the four sides of the piezoelectric array element area.

[0028] Reference numerals:

[0029] 1-piezoelectric layer; 10-grooves; 100-piezoelectric sheet; 11-piezoelectric array element area; 12-array element signal lead area; 13-signal electrode area; 2-acoustic matching layer; 3-sound-absorbing backing layer; 4-flexible circuit board; 5-acoustic lens; 6-packaging material. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] The present invention provides an array ultrasonic transducer that does not increase the complexity and difficulty of the process. The piezoelectric layer is divided into a piezoelectric array element region and an array element signal lead region. A flexible circuit board is bonded to the array element signal lead region to achieve electrical interconnection with the piezoelectric layer. The flexible circuit board is distributed around the periphery of the piezoelectric layer and does not need to be directly bonded to the piezoelectric array element, thereby avoiding being sandwiched between the piezoelectric layer and the backing layer to affect the performance of the transducer.

[0032] Specifically, see Figure 1a and Figure 1b , which is a schematic diagram of the internal structure of the array ultrasonic transducer provided by the present invention. The array ultrasonic transducer consists of a piezoelectric layer 1, an acoustic matching layer 2, a sound-absorbing backing layer 3, a flexible circuit board 4, an acoustic lens 5, and a housing. The sound-absorbing backing layer 3, the piezoelectric layer 1, the acoustic matching layer 2, and the acoustic lens 5 are stacked in sequence, and the housing encapsulates the internal structure of the array ultrasonic transducer. The piezoelectric layer 1 emits ultrasonic waves; the acoustic matching layer 2 is used to match the acoustic impedance between the piezoelectric layer 1 and the external object; the sound-absorbing backing layer 3 absorbs ultrasonic waves emitted in the direction of the sound-absorbing backing layer 3; and the flexible circuit board 4 is used to achieve electrical interconnection between the piezoelectric layer 1 and the external circuit. Compared with the traditional lead process, the use of the flexible circuit board 4 to achieve electrical interconnection can simplify the lead process of the array ultrasonic transducer. Furthermore, in the present invention, the flexible circuit board 4 is disposed around the periphery of the piezoelectric layer 1 to prevent reflections of ultrasonic waves intended for absorption directed toward the sound-absorbing backing layer 3, which could affect imaging quality. The acoustic lens 5 focuses the acoustic field, focusing the sound waves emitted by the piezoelectric layer 1. The acoustic matching layer 2 and the sound-absorbing backing layer 3 can be fabricated using methods such as direct bonding, casting, centrifugation, or vapor deposition. Alternatively, the flexible circuit board 4 can be disposed on the surface of the piezoelectric layer 1 facing the sound-absorbing backing layer 3, on the surface of the piezoelectric layer 1 facing the acoustic matching layer 2, or on the surface of the acoustic matching layer 2 facing the acoustic lens 5.

[0033] See also Figure 2a and Figure 2b, is a schematic diagram of the specific structure of the piezoelectric layer 1. The piezoelectric layer 1 includes a piezoelectric sheet 100 and electrode surfaces disposed on both sides of the piezoelectric sheet 100. The piezoelectric sheet 100 includes multiple piezoelectric elements. The gaps between the piezoelectric elements are filled with an insulating material, such as epoxy resin. The top and bottom surfaces of the piezoelectric sheet 100 are covered with electrodes: one surface is a signal electrode, and the other surface is a ground electrode. The electrodes on the signal electrode surface cover the area outside the gaps between the piezoelectric elements, leaving no electrodes in the gaps. The electrodes on the ground electrode surface can cover only the area outside the gaps between the piezoelectric elements, or they can cover the entire surface except for the grooves. The ground electrode surface includes two parts, a piezoelectric element region 11 and an element signal lead region 12, disposed on the same piece of piezoelectric material. The piezoelectric material size and the piezoelectric material spacing size in the two regions are more than 90% similar. The piezoelectric element region 11 and the element signal lead region 12 are formed on the same piece of piezoelectric material and can be integrally formed, avoiding increased process complexity and difficulty. In some embodiments, in different regions of the same piece of piezoelectric material in the piezoelectric layer 1 , the size of the piezoelectric array elements and the spacing between the piezoelectric array elements are equal.

[0034] In this embodiment, the ground electrode surface is provided with a groove 10, which separates the piezoelectric array element region 11 and the array element signal lead region 12. The array element signal lead region 12 is distributed at the edge of the piezoelectric layer 1, outside the piezoelectric array element region 11. The groove 10 can be created by any means capable of micromachining ceramics, such as mechanical cutting, laser cutting, and ion etching. The piezoelectric layer 1 can be made of a traditional piezoelectric material, a 1-3 composite piezoelectric material, or a 2-2 composite piezoelectric material. The piezoelectric array element region 11 and the array element signal lead region 12 of the ground electrode surface are covered with conductive electrodes, while no conductive electrodes are present at the groove 10. The signal electrode region 13 of the signal electrode surface is covered with a conductive electrode, while the surface of the gap between the piezoelectric array elements is free of conductive electrodes.

[0035] Furthermore, the orientation of the piezoelectric layer 1 is associated with the location of the flexible circuit board 4. Specifically, the flexible circuit board 4 is located in the direction of the signal electrode surface of the piezoelectric layer 1. In some embodiments, the flexible circuit board 4 is disposed on the surface of the piezoelectric layer 1 facing the sound-absorbing backing layer 3 and is connected to the piezoelectric layer 1. The ground electrode surface of the piezoelectric layer 1 is bonded to the acoustic matching layer 2. Optionally, the acoustic matching layer 2 comprises one or more layers. Grooves may also be provided in the acoustic matching layer 2. Specifically, grooves are provided in the acoustic matching layer 2 at the locations where the grooves 10 are located in the piezoelectric layer 1. Through the interaction of the electric field, separate piezoelectric array element regions 11 and array element signal lead regions 12 are formed in the piezoelectric layer 1. The location of the grooves corresponds to the boundary between the piezoelectric array element regions 11 and the array element signal lead regions 12. The signal electrode surface of the piezoelectric layer 1 faces the sound-absorbing backing layer 3. The piezoelectric array element region 11 is directly covered by the sound-absorbing backing layer 3. The array element signal lead region 12 is distributed around the periphery of the piezoelectric layer 1 and is electrically connected to one end of the flexible circuit board 4. Part of the flexible circuit board 4 covers the array element signal lead region 12. The leads of the flexible circuit board 4 correspond one-to-one with the signal electrodes of each piezoelectric array element. The other end of the flexible circuit board 4 is led outward to facilitate the electrical connection between the array element signal lead region 12 and the flexible circuit board 4. The flexible circuit board 4 is electrically connected to the periphery of the piezoelectric layer 1, not between the piezoelectric layer 1 and the sound-absorbing backing layer 3, eliminating the impact of the flexible circuit board 4 on the performance of the array ultrasonic transducer. When the leads are extended from multiple sides, the number of flexible circuit boards 4 can be multiple or one, and the flexible circuit board 4 is generally rectangular or L-shaped. Optionally, the flexible circuit board 4 may be covered with the packaging material 6 or not. Specifically, when the sound absorbing backing layer 3 can cover the entire piezoelectric layer, there is no packaging material 6; when the sound absorbing backing layer 3 only covers the piezoelectric element area 11, the packaging material 6 is provided.

[0036] Optionally, the flexible circuit board 4 can also be disposed on the surface of the acoustic matching layer 2 facing the acoustic lens 5. When the acoustic matching layer 2 is a conductor, it is connected to the acoustic matching layer 2, and the signal electrode surface of the piezoelectric layer 1 is bonded to the acoustic matching layer 2. Specifically, the acoustic matching layer 2 is a single-layer structure, and grooves 10 are provided on the piezoelectric layer 1 to separate the piezoelectric array element area 11 from the array element signal lead area 12. To facilitate packaging of the internal structure of the ultrasonic transducer, the flexible circuit board 4 can be bent to provide a regular structure. In some embodiments, each flexible circuit board 4 includes two parts: one part covers the array element signal lead area 12, and the other part conforms to the outer contour of the entire internal structure of the array ultrasonic transducer. In the direction of the circuit extension of the flexible circuit board 4, the cross-section of the flexible circuit board 4 is L-shaped.

[0037] The piezoelectric array element can be a one-dimensional array or a two-dimensional array. The one-dimensional array can be a linear array, a phased array, a convex array, etc., preferably a one-dimensional linear array. The array element signal lead area 12 can be distributed on either side or both sides of the piezoelectric array element area 11. When distributed on both sides, the flexible circuit board 4 can be two or one. See the attached manual. Figure 3a , is a schematic diagram of the structure when the array element signal lead area 12 is distributed on one side of the piezoelectric array element area 11. The flexible circuit board 4 is rectangular in shape, with one end covering the array element signal lead area 12 for connection and the other end leading outward. Figure 3b and Figure 3c , respectively, are schematic diagrams illustrating the configuration of two and one flexible circuit boards 4, when the array element signal lead areas 12 are distributed on both sides of the piezoelectric array element area 11. Alternatively, two rectangular flexible circuit boards 4 can be used, with one end covering the array element signal lead areas 12 on either side for connection, with the other ends extending outward. Alternatively, a single flexible circuit board 4 can be cut out to create a hollowed-out area corresponding to the size of the piezoelectric array element area 11, and then covered with the array element signal lead areas 12 to achieve electrical connection to the piezoelectric layer 1.

[0038] The array element signal lead area 12 can be distributed on any side, any two sides, any three sides, or all four sides of the piezoelectric array element area 11 arranged in a two-dimensional array. Figure 4a 、 4b In the example of FIG4c, where all four sides of the flexible circuit board have array element signal lead areas 12, the number of flexible circuit boards 4 can be selected: one, two, or four. When there is only one flexible circuit board 4, the circuits on the flexible circuit board 4 are arranged in a cross shape, with rectangular cutout areas cut out at the intersections of the circuits. The number of circuits surrounding the through-holes is equal to the number of electrodes on the array element signal lead areas 12. The flexible circuit board 4 is then placed over the array element signal lead areas 12, with the circuits on the flexible circuit board 4 corresponding one-to-one with the electrodes on the array element signal lead areas 12. When there are two flexible circuit boards 4, after splicing, the flexible circuit boards 4 do not cover the piezoelectric array element areas 11, but only cover the array element signal lead areas 12 on two adjacent sides of the piezoelectric layer 1. The circuits extend horizontally outward, forming an L-shape in plan. Alternatively, four flexible circuit boards 4 can be used to cover the array element signal lead areas 12 on the periphery of the piezoelectric layer 1 to achieve electrical connection with the piezoelectric layer 1.

[0039] In summary, the present invention provides an array ultrasonic transducer with simple process, reliability and strong operability. Its piezoelectric layer includes a piezoelectric array element region and an array element signal lead region. The array element signal lead region is distributed on the periphery of the piezoelectric layer and is electrically connected to one end of the flexible circuit board, so that the flexible circuit board is distributed on the periphery of the piezoelectric layer and is not between the piezoelectric layer and the sound-absorbing backing layer, eliminating the influence of the flexible circuit board on the array ultrasonic transducer. In addition, the array element signal lead region and the piezoelectric array element region are on the same piece of piezoelectric material and can be integrally formed, avoiding increasing the complexity and difficulty of the process. Furthermore, the leads of the flexible circuit board correspond one-to-one with the signal electrodes of each piezoelectric array element, facilitating the electrical connection between the array element signal lead region and the flexible circuit board. The array ultrasonic transducer provided by the present invention has a high yield rate, strong reliability, a simple preparation process, strong operability, and is applicable to array ultrasonic transducers of all frequency ranges.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. In addition to the above embodiments, there may also be different variations. The technical features of the above embodiments may be combined with each other. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An array ultrasonic transducer, characterized in that: It includes a sound absorbing backing layer, a piezoelectric layer, an acoustic matching layer and an acoustic lens arranged in sequence; The piezoelectric layer includes an array element signal lead area and a piezoelectric array element area; Also included is a flexible circuit board, the flexible circuit board being electrically connected to the array element signal lead area; The piezoelectric layer includes a piezoelectric sheet and a ground electrode surface provided on one surface of the piezoelectric sheet and a signal electrode surface provided on the other surface of the piezoelectric sheet. The ground electrode surface is provided with a groove. The ground electrode surface includes the piezoelectric array element region and the array element signal lead region. The groove corresponds to the boundary between the array element signal lead region and the piezoelectric array element region. The flexible circuit board is electrically connected to the signal electrode surface. The piezoelectric sheet includes a plurality of piezoelectric array elements, gaps are set between the piezoelectric array elements, each of the piezoelectric array elements has a ground electrode located on the ground electrode surface and a signal electrode located on the signal electrode surface, and the leads of the flexible circuit board correspond one-to-one to the signal electrodes of each piezoelectric array element.

2. The array ultrasonic transducer according to claim 1, wherein: The flexible circuit board is arranged between the piezoelectric layer and the sound absorbing backing layer, and the signal electrode faces the sound absorbing backing layer.

3. The array ultrasonic transducer according to claim 1, wherein: The flexible circuit board is disposed between the piezoelectric layer and the acoustic matching layer, and the signal electrode faces the acoustic matching layer.

4. The array ultrasonic transducer according to claim 1, wherein: The flexible circuit board is disposed between the acoustic matching layer and the acoustic lens, and the signal electrode faces the acoustic matching layer.

5. The arrayed ultrasonic transducer according to claim 1, wherein: The gap is filled with an insulating material.

6. The arrayed ultrasonic transducer according to claim 1, wherein: The piezoelectric array element region is a one-dimensional array; The array element signal lead area is distributed on one side or both sides of the piezoelectric array element area.

7. The arrayed ultrasonic transducer according to claim 1, wherein: The piezoelectric array element area is arranged in a two-dimensional array; The array element signal lead area is distributed on any 1-4 sides of the piezoelectric array element area.

8. The arrayed ultrasonic transducer according to any one of claims 1 to 7, characterized in that: The piezoelectric layer includes a piece of piezoelectric material, and the array element signal lead area and the piezoelectric array element area are respectively arranged in different areas on the piezoelectric material.

9. The arrayed ultrasonic transducer according to any one of claims 1 to 7, wherein: The piezoelectric array element size and the distance between the piezoelectric array elements in the array element signal lead area and the piezoelectric array element area are close to each other by more than 90%.

10. The arrayed ultrasonic transducer according to any one of claims 1 to 7, characterized in that: The number of the flexible circuit board is one, and the flexible circuit board is provided with a hollow area, and the hollow area corresponds to the size of the piezoelectric array element area.

11. The arrayed ultrasonic transducer according to any one of claims 1 to 7, characterized in that: The number of the flexible circuit boards is more than two, and the flexible circuit boards do not cover the piezoelectric array element area after being spliced.

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