Ultrasonic transducer and manufacturing method thereof

Abstract

The present invention relates to an ultrasonic transducer and a method of manufacturing the same, the ultrasonic transducer comprising: a backing; the piezoelectric crystal layer is arranged on the back lining; the matching layer is arranged on one surface, far away from the backing, of the piezoelectric crystal layer; wherein the piezo-electric crystal layer comprises a first piezo-electric crystal layer and a second piezo-electric crystal layer, a first electrode and a second electrode are arranged on the first piezo-electric crystal layer at intervals, a third electrode and a fourth electrode are arranged on the second piezo-electric crystal layer at intervals, and the first piezo-electric crystal layer and the second piezo-electric crystal layer are mutually coupled. The first electrode and the third electrode are connected to form a positive electrode, the second electrode and the fourth electrode are connected to form a negative electrode, the positive electrode and the negative electrode are isolated, and one of the positive electrode and the negative electrode is electrically connected with the flexible printed circuit board through the matching layer. By optimizing the electrode leading-out mode and the multilayer matching process of the piezoelectric crystal, the sensitivity of the transducer is improved, the performance of the transducer is improved, meanwhile, the manufacturing process is simplified, and the cost is reduced.

Description

Technical Field

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

[0002] Medical ultrasonic transducers play a key role in ultrasonic imaging, and their performance directly affects the quality of ultrasonic images. In the prior art, the manufacturing process of the transducer is complex, especially in the electrode lead-out of the piezoelectric crystal and the design of the multi-layer matching layer. In the traditional method, the positive and negative electrode lead-out of the piezoelectric crystal is complicated, and the matching layer design is unreasonable, resulting in high production difficulty, high cost and unstable performance.

[0003] The invention patent application with publication number CN113182157A specifically discloses a flexible piezoelectric ultrasonic transducer, including a backing layer, a bottom electrode, a piezoelectric layer, a top electrode, and a matching layer. The manufacturing method of the disclosed transducer has the problem of complex positive and negative electrode extraction. Summary of the invention

[0004] Based on this, it is necessary to provide an ultrasonic transducer and a method for manufacturing the same in response to the above-mentioned technical problems existing in the prior art. By optimizing the electrode lead-out method and the multi-layer matching process of the piezoelectric crystal, the sensitivity of the transducer is increased and its performance is improved. At the same time, the manufacturing process is simplified and the production difficulty and cost are reduced.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] An ultrasonic transducer, comprising:

[0007] Backing;

[0008] A piezoelectric crystal layer, wherein the piezoelectric crystal layer is disposed on a backing;

[0009] A matching layer, wherein the matching layer is arranged on a side of the piezoelectric crystal layer away from the backing;

[0010] Among them, the piezoelectric crystal layer includes a first piezoelectric crystal layer and a second piezoelectric crystal layer, a first electrode and a second electrode are arranged on the first piezoelectric crystal layer, a third electrode and a fourth electrode are arranged on the second piezoelectric crystal layer, the first piezoelectric crystal layer and the second piezoelectric crystal layer are coupled to each other, the first electrode and the third electrode are connected to form a positive electrode, the second electrode and the fourth electrode are connected to form a negative electrode, the positive electrode and the negative electrode are isolated, and one of the positive electrode or the negative electrode is electrically connected to the flexible printed circuit board through a matching layer. First, the piezoelectric crystal layer of the present invention is prepared by a lamination process, which can increase the capacitance compared to a single-layer piezoelectric crystal, and can reach 4 times the capacitance of a single-layer piezoelectric crystal layer, thereby increasing the sensitivity of the transducer; secondly, the special structure of the piezoelectric crystal layer of the present invention makes it easy to lead out the positive and negative electrodes.

[0011] In a feasible implementation, the first piezoelectric crystal layer includes a first main surface, a second main surface, a first side surface, and a second side surface, the first main surface and the second main surface are arranged opposite to each other, the first side surface and the second side surface are arranged opposite to each other, and the first side surface and the second side surface connect the first main surface and the second main surface, the first electrode is arranged on the first main surface, the first side surface, and the second main surface, the second electrode is arranged on the first main surface, the second side surface, and the second main surface, the first notch is arranged on the first main surface, the second notch is arranged on the second main surface, and the first electrode and the second electrode are separated by the first notch and the second notch;

[0012] The second piezoelectric crystal layer includes a third main surface, a fourth main surface, a third side surface, and a fourth side surface, the third main surface and the fourth main surface are arranged opposite to each other, the third side surface and the fourth side surface are arranged opposite to each other and the third side surface and the fourth side surface are connected to each other, a third electrode is arranged on the third main surface, the third side surface, and the fourth main surface, a fourth electrode is arranged on the third main surface, the fourth side surface, and the fourth main surface, a third notch is arranged on the third main surface, a fourth notch is arranged on the fourth main surface, and the third electrode and the fourth electrode are spaced apart by the third notch and the fourth notch;

[0013] The second main surface of the first piezoelectric crystal layer is coupled with the third main surface of the second piezoelectric crystal layer, the second notch and the third notch are opposite to each other, the first electrode and the third electrode are connected to form a positive electrode, the second electrode and the fourth electrode are connected to form a negative electrode, and the positive electrode and the negative electrode are isolated from each other.

[0014] In a feasible implementation, the matching layer includes a first impedance matching layer, the first impedance matching layer is arranged on a side of the piezoelectric crystal layer away from the backing, the acoustic impedance of the first impedance matching layer is between 15-20 MRayl, a conductive layer is arranged on the first impedance matching layer, and the negative electrode is electrically connected to the flexible printed circuit board through the conductive layer on the first matching layer. In the present invention, a conductive layer is arranged on the first impedance matching layer, and the electrode on the piezoelectric crystal layer is moved up to the first impedance matching layer.

[0015] In a feasible implementation, the matching layer includes a second impedance matching layer, the second impedance matching layer is arranged on a side of the first impedance matching layer away from the backing, the acoustic impedance of the second impedance matching layer is between 5-15 MRayl, the second impedance matching layer is made of a conductive material, and the second impedance matching layer is electrically connected to the conductive layer. The second impedance matching layer of the present invention is made of a conductive material, and the electrode on the piezoelectric crystal layer is moved up to the second impedance matching layer.

[0016] In a feasible implementation, the matching layer includes a third impedance matching layer, the third impedance matching layer is arranged on a side of the second impedance matching layer away from the backing, the acoustic impedance of the third impedance matching layer is between 2-5 MRayl, the third impedance matching layer is made of a conductive material, and the third impedance matching layer is electrically connected to the second impedance matching layer. The third impedance matching layer of the present invention is made of a conductive material, and the electrode on the piezoelectric crystal layer is moved up to the third impedance matching layer.

[0017] The present invention adopts a multi-layer impedance matching layer arrangement to ensure the acoustic matching effect of the transducer.

[0018] In a feasible implementation, an electromagnetic shielding film is also included, which is arranged on a side of the third impedance matching layer away from the backing, and is made of a conductive material, and is electrically connected to the third impedance matching layer and the flexible printed circuit board. The present invention leads out the negative electrode of the piezoelectric crystal layer through the electromagnetic shielding film and contacts the negative electrode point on the flexible printed circuit board. In this way, the introduction of the negative electrode copper foil is avoided, the cutting difficulty is reduced, and the manufacturing process is simplified.

[0019] In a possible implementation, a lens layer is further included, and the lens layer is disposed on a side of the electromagnetic shielding film away from the backing.

[0020] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0021] A method for manufacturing the ultrasonic transducer as described above comprises the following steps:

[0022] (1) forming a piezoelectric crystal layer on a backing, wherein the preparation of the piezoelectric crystal layer comprises the following steps:

[0023] Prepare a first piezoelectric crystal layer, form an electrode material layer on a first main surface, a second main surface, a first side surface, and a second side surface of the first piezoelectric crystal layer, form a first notch on the first main surface, and form a second notch on the second main surface, so as to divide the electrode material layer into a first electrode and a second electrode isolated from each other;

[0024] Prepare a second piezoelectric crystal layer, form an electrode material layer on the third main surface, the fourth main surface, the third side surface, and the fourth side surface of the second piezoelectric crystal layer, form a third notch on the third main surface, and form a fourth notch on the fourth main surface to divide the electrode material layer into a third electrode and a fourth electrode isolated from each other;

[0025] The second main surface of the first piezoelectric crystal layer and the third main surface of the second piezoelectric crystal layer are coupled to each other, the second notch and the third notch are opposite to each other, the first electrode and the third electrode are connected to form a positive electrode, the second electrode and the fourth electrode are connected to form a negative electrode, and the positive electrode and the negative electrode are isolated from each other.

[0026] (2) forming a matching layer on the side of the piezoelectric crystal layer away from the backing, wherein the matching layer is electrically connected to the negative electrode;

[0027] (3) Electrically connect the matching layer to the flexible printed circuit board.

[0028] The present invention adopts a lamination process to increase the sensitivity of the transducer, and adopts a special electrode manufacturing method to ensure that the positive and negative electrodes are conveniently and stably led out.

[0029] In a feasible implementation, step (2) specifically includes the following steps:

[0030] (a) a first impedance matching layer is formed on a surface of the piezoelectric crystal layer away from the backing, the acoustic impedance of the first impedance matching layer is between 15-20 MRayl, and a conductive layer is formed on the first impedance matching layer, the conductive layer is electrically connected to the negative electrode, so as to improve the conductivity and matching effect and ensure the high efficiency and stability of signal transmission;

[0031] (b) a second impedance matching layer is made of a conductive material on a surface of the first impedance matching layer away from the backing, and the acoustic impedance of the second impedance matching layer is between 5 and 15 MRayl to ensure good conductivity and matching effect;

[0032] (c) A third impedance matching layer is made of conductive material on a side of the second impedance matching layer away from the backing, and the acoustic impedance of the third impedance matching layer is between 2-5 MRayl to ensure good conductivity and matching effect.

[0033] The present invention adopts a multi-layer matching process to ensure the acoustic matching effect of the transducer, and at the same time can significantly improve the signal transmission efficiency and image quality of the transducer, and improve the electroacoustic conversion efficiency of the transducer.

[0034] In a feasible implementation, the following steps are also included: an electromagnetic shielding film is made of a conductive material on the side of the matching layer away from the backing, and the matching layer is electrically connected to the flexible printed circuit board through the electromagnetic shielding film. Through this negative electrode lead-out method, the introduction of negative electrode copper foil is avoided, the cutting difficulty is reduced, and the manufacturing process is simplified.

[0035] Due to the adoption of the above technical solution, the present invention has the following advantages compared with the prior art:

[0036] 1. The present invention adopts a lamination process to increase the sensitivity of the piezoelectric crystal and improve the performance of the transducer;

[0037] 2. The multi-layer matching process of the present invention significantly improves the signal transmission efficiency and image quality of the transducer;

[0038] 3. The present invention adopts a special electrode manufacturing method to simplify the manufacturing process and reduce production difficulty and cost;

[0039] 4. The present invention adopts multi-layer matching technology and electromagnetic shielding design to reduce noise interference and improve the stability and reliability of the transducer;

[0040] 5. The present invention avoids the introduction of negative electrode copper foil through an innovative electrode lead-out method, reduces cutting difficulty, improves production efficiency, and simultaneously improves the signal transmission efficiency and electroacoustic conversion efficiency of the transducer.

[0041] In summary, the present invention has broad application prospects and significant technical advantages in the field of medical ultrasonic imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic structural diagram of the first piezoelectric crystal layer in an embodiment of the present invention;

[0043] Figure 2 is a schematic structural diagram of the second piezoelectric crystal layer in an embodiment of the present invention;

[0044] Figure 3 A schematic diagram of the structure of a piezoelectric crystal layer in an embodiment of the present invention;

[0045] Figure 4 Schematic diagram of the structure of an ultrasonic transducer according to an embodiment of the present invention;

[0046] Among them, 1. backing; 2. first piezoelectric crystal layer; 21. first main surface; 22. second main surface; 23. first side; 24. second side; 25. first notch; 26. second notch; 27. first electrode; 28. second electrode; 3. second piezoelectric crystal layer; 31. third main surface; 32. fourth main surface; 33. third side; 34. fourth side; 35; third notch; 36. fourth notch; 37. third electrode; 38. fourth electrode; 4. matching layer; 41. first impedance matching layer; 42. second impedance matching layer; 43. third impedance matching layer; 5. conductive layer; 6. electromagnetic shielding film; 7. lens layer; 8. flexible printed circuit board; 9. positive electrode; 10. negative electrode. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0048] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are for illustrative purposes only.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In this application, " / " means "or".

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0051] In the prior art, the manufacturing process of the transducer is complex, especially in the electrode lead-out of the piezoelectric crystal and the design of the multi-layer matching layer. In the traditional method, the positive and negative electrode lead-out of the piezoelectric crystal is complicated, and the matching layer design is unreasonable, resulting in high production difficulty, high cost and unstable performance.

[0052] On this basis, the present invention provides an ultrasonic transducer and a manufacturing method thereof, wherein the ultrasonic transducer comprises:

[0053] Backing;

[0054] A piezoelectric crystal layer, wherein the piezoelectric crystal layer is disposed on a backing;

[0055] A matching layer, wherein the matching layer is arranged on a side of the piezoelectric crystal layer away from the backing;

[0056] Among them, the piezoelectric crystal layer includes a first piezoelectric crystal layer and a second piezoelectric crystal layer, the first piezoelectric crystal layer is provided with a first electrode and a second electrode, the second piezoelectric crystal layer is provided with a third electrode and a fourth electrode, the first piezoelectric crystal layer and the second piezoelectric crystal layer are coupled with each other, the first electrode and the third electrode are connected to form a positive electrode, the second electrode and the fourth electrode are connected to form a negative electrode, the positive electrode and the negative electrode are isolated from each other, and one of the positive electrode or the negative electrode is electrically connected to the flexible printed circuit board through a matching layer.

[0057] The present invention increases the sensitivity of the transducer and improves its performance by optimizing the electrode lead-out method of the piezoelectric crystal, while simplifying the manufacturing process and reducing the production difficulty and cost.

[0058] The present invention is described in detail below with reference to specific embodiments.

[0059] Example 1

[0060] like Figure 1-4 As shown, the ultrasonic transducer of this embodiment includes a backing 1, a piezoelectric crystal layer, a matching layer 4, an electromagnetic shielding film 6, and a lens layer 7.

[0061] The backing 1 of this embodiment is a commonly used backing in the art and is not considered as an invention point and will not be described in detail.

[0062] The piezoelectric crystal layer of this embodiment is arranged on the backing 1 and is prepared by a lamination process. Compared with a single-layer piezoelectric crystal, the capacitance can be increased, and the capacitance can reach 4 times that of a single-layer piezoelectric crystal layer, thereby increasing the sensitivity of the transducer. The piezoelectric crystal layer includes a first piezoelectric crystal layer 2 and a second piezoelectric crystal layer 3. The first piezoelectric crystal layer 2 is arranged on the side of the second piezoelectric crystal layer 3 away from the backing 1. The first piezoelectric crystal layer 2 is provided with a first electrode 27 and a second electrode 28 at intervals, and the second piezoelectric crystal layer 3 is provided with a third electrode 37 and a fourth electrode 38 at intervals. The first piezoelectric crystal layer 2 and the second piezoelectric crystal layer 3 are coupled to each other, the first electrode 27 and the third electrode 37 are connected to form a positive electrode 9, the second electrode 28 and the fourth electrode 29 are connected to form a negative electrode 10, and the positive electrode 9 and the negative electrode 10 are arranged in isolation.

[0063] Specifically, the first piezoelectric crystal layer 2 includes a first main surface 21 (upper surface), a second main surface 22 (lower surface), a first side surface 23 (right side surface), and a second side surface 24 (left side surface). The first main surface 21 and the second main surface 22 are arranged opposite to each other, the first side surface 23 and the second side surface 24 are arranged opposite to each other and the first side surface 23 and the second side surface 24 connect the first main surface 21 and the second main surface 22. The first electrode 27 is arranged on the first main surface 21, the first side surface 23 and the second main surface 22, the second electrode 28 is arranged on the first main surface 21, the second side surface 24 and the second main surface 22, a first notch 25 is arranged on the first main surface 21, a second notch 26 is arranged on the second main surface 22, and the first electrode 27 and the second electrode 28 are separated by the first notch 25 and the second notch 26.

[0064] In this embodiment, the first notch 25 is close to the first side surface 23 on the first main surface 21, that is, the first notch 25 is arranged on the right side of the first main surface 21. The second notch 26 is close to the second side surface 24 on the second main surface 22, that is, the second notch 26 is arranged on the left side of the second main surface 22.

[0065] The second piezoelectric crystal layer 3 includes a third major surface 31 (upper surface), a fourth major surface 32 (lower surface), a third side surface 33 (right side surface), and a fourth side surface 34 (left side surface). The third major surface 31 and the fourth major surface 32 are arranged opposite to each other, the third side surface 33 and the fourth side surface 34 are arranged opposite to each other, and the third side surface 33 and the fourth side surface 34 connect the third major surface 31 and the fourth major surface 32. The third electrode 37 is arranged on the third major surface 31, the third side surface 33 and the fourth major surface 32. The fourth electrode 38 is arranged on the third major surface 31, the fourth side surface 34 and the fourth major surface 32. A third notch 35 is arranged on the third major surface 31, and a fourth notch 36 is arranged on the fourth major surface 32. The third electrode 37 and the fourth electrode 38 are separated by the third notch 35 and the fourth notch 36.

[0066] In this embodiment, the third notch 35 is close to the fourth side surface 34 on the third main surface 31, that is, the third notch 35 is arranged on the left side of the third main surface 31. The fourth notch 36 is close to the third side surface 33 on the fourth main surface 32, that is, the fourth notch 36 is arranged on the right side of the fourth main surface 32.

[0067] The second main surface 22 of the first piezoelectric crystal layer 2 and the third main surface 31 of the second piezoelectric crystal layer 3 are coupled to each other through an adhesive, the distance from the second notch 26 to the left side of the second main surface 22 is equal to the distance from the third notch 35 to the left side of the third main surface 31, and the widths of the second notch 26 and the third notch 35 are equal, ensuring that the second notch 26 and the third notch 35 are opposite to each other, the first electrode 27 and the third electrode 37 are connected to form the positive electrode 9, the second electrode 28 and the fourth electrode 38 are connected to form the negative electrode 10, and the positive electrode 9 and the negative electrode 10 are isolated. The special structure of the piezoelectric crystal layer in this embodiment makes it easy to lead the positive electrode 9 and the negative electrode 10 from the flexible printed circuit board 8 (FPC).

[0068] In order to better improve production efficiency, the first piezoelectric crystal layer 2 and the second piezoelectric crystal layer 3 are prepared with the same size, and the distances from the notches on the upper and lower surfaces to the nearest side surfaces are equal, and the widths of the notches are equal, which simplifies the production process and improves production efficiency.

[0069] In this embodiment, the matching layer 4 is arranged on the side of the piezoelectric crystal layer away from the backing 1. The matching layer 4 in this embodiment is conductive, and the negative electrode 10 is led out from the upper surface of the matching layer 4. The matching layer 4 includes a first impedance matching layer 41, a second impedance matching layer 42, and a third impedance matching layer 43. This embodiment adopts a multi-layer impedance matching layer arrangement to ensure the acoustic matching effect of the transducer.

[0070] Specifically, the first impedance matching layer 41 is arranged on the side of the piezoelectric crystal layer away from the backing 1, and the first impedance matching layer 41 is arranged on the side of the first piezoelectric crystal layer 2 away from the backing 1. The acoustic impedance of the first impedance matching layer 41 is between 15-20 MRayl, and the first impedance matching layer 41 is provided with a conductive layer 5, which is arranged on the upper surface, the left side surface and the lower surface of the first impedance matching layer 41. The conductive layer 5 can completely or partially cover the upper surface of the first impedance matching layer 41, and completely cover the left side surface of the first impedance matching layer 41. The projection of the conductive layer 5 on the lower surface of the first impedance matching layer 41 on the backing 1 is less than or equal to the projection of the second electrode 28 on the upper surface of the first piezoelectric crystal layer 2 on the backing 1. The conductive layer 5 is electrically insulated from the positive electrode 9 on the piezoelectric crystal layer.

[0071] In this embodiment, a conductive layer 5 is provided on the first impedance matching layer 41 , and the negative electrode 10 on the piezoelectric crystal layer is moved up to the first impedance matching layer 41 .

[0072] The second impedance matching layer 42 is arranged on the side of the first impedance matching layer 41 away from the backing 1, the acoustic impedance of the second impedance matching layer 42 is between 5-15 MRayl, the second impedance matching layer 42 is made of conductive material, and the second impedance matching layer 42 is electrically connected to the conductive layer 5. In this embodiment, the second impedance matching layer 42 is made of conductive material, and the negative electrode 10 on the piezoelectric crystal layer is moved up to the second impedance matching layer 42.

[0073] The third impedance matching layer 43 is arranged on the side of the second impedance matching layer 42 away from the backing 1, the acoustic impedance of the third impedance matching layer 43 is between 2-5 MRayl, the third impedance matching layer 43 is made of conductive material, and the third impedance matching layer 43 is electrically connected to the second impedance matching layer 42. In this embodiment, the third impedance matching layer 43 is made of conductive material, and the negative electrode 10 on the piezoelectric crystal layer is moved up to the third impedance matching layer 43.

[0074] In this embodiment, the electromagnetic shielding film 6 is arranged on the side of the third impedance matching layer 43 away from the backing 1, the electromagnetic shielding film 6 is made of a conductive material, and the electromagnetic shielding film 6 is electrically connected to the third impedance matching layer 43 and the flexible printed circuit board 8. Specifically, the electromagnetic shielding film 6 includes a body arranged on the third impedance matching layer 43 and an extension portion extending toward the matching layer 4, an insulating layer is arranged between the extension portion and the matching layer, and the extension portion is in contact with the negative pole on the flexible printed circuit board 8.

[0075] In this embodiment, the negative electrode 10 of the piezoelectric crystal layer is led out through the electromagnetic shielding film 6 and contacts the negative electrode point on the flexible printed circuit board 8. In this way, the introduction of the negative electrode copper foil is avoided, the cutting difficulty is reduced, and the manufacturing process is simplified.

[0076] In this embodiment, the lens layer 7 is disposed on a surface of the electromagnetic shielding film 6 that is away from the backing 1 .

[0077] The method for manufacturing the ultrasonic transducer of this embodiment comprises the following steps:

[0078] (1) forming a piezoelectric crystal layer on the backing 1, the preparation of the piezoelectric crystal layer comprises the following steps:

[0079] Prepare a first piezoelectric crystal layer 2, form an electrode material layer on a first main surface 21, a second main surface 22, a first side surface 23, and a second side surface 24 of the first piezoelectric crystal layer 2 by using a sputtering, electron beam, thermal evaporation, or electroplating method, form a first notch 25 on the first main surface 21, and form a second notch 26 on the second main surface 22, so as to divide the electrode material layer into a first electrode 27 and a second electrode 28 isolated from each other;

[0080] Prepare a second piezoelectric crystal layer 3, form an electrode material layer on the third main surface 31, the fourth main surface 32, the third side surface 33, and the fourth side surface 34 of the second piezoelectric crystal layer 3 by sputtering, electron beam, thermal evaporation, or electroplating, form a third notch 35 on the third main surface 31, and form a fourth notch 36 on the fourth main surface 32, so as to divide the electrode material layer into a third electrode 37 and a fourth electrode 38 isolated from each other;

[0081] The second main surface 22 of the first piezoelectric crystal layer 2 and the third main surface 31 of the second piezoelectric crystal layer 3 are coupled to each other, the second notch 26 and the third notch 35 are opposite to each other, the first electrode 27 and the third electrode 37 are connected to form the positive electrode 9, the second electrode 28 and the fourth electrode 38 are connected to form the negative electrode 10, and the positive electrode 9 and the negative electrode 10 are isolated and arranged.

[0082] (2) Making a matching layer 4 on the side of the piezoelectric crystal layer away from the backing 1, specifically comprising the following steps:

[0083] (a) A first impedance matching layer 41 is formed on the side of the piezoelectric crystal layer away from the backing, that is, on the upper surface of the first piezoelectric crystal layer 2, and the acoustic impedance of the first impedance matching layer 41 is between 15-20 MRayl. A conductive layer 5 is formed on the first impedance matching layer 41, and the conductive layer 5 is arranged on the upper surface, the left side surface and the lower surface of the first impedance matching layer 41. The conductive layer 5 can completely or partially cover the upper surface of the first impedance matching layer 41, and completely cover the left side surface of the first impedance matching layer 41. The projection of the conductive layer 5 on the lower surface of the first impedance matching layer 41 on the backing 1 is less than or equal to the projection of the second electrode 28 on the upper surface of the first piezoelectric crystal layer 2 on the backing 1. The conductive layer 5 is electrically insulated from the positive electrode 9 on the piezoelectric crystal layer. The conductive layer 5 is electrically connected to the negative electrode 10 to improve the conductivity and matching effect, and ensure the high efficiency and stability of signal transmission.

[0084] (b) A second impedance matching layer 42 is made of conductive material on the side of the first impedance matching layer 41 away from the backing 1. The acoustic impedance of the second impedance matching layer 42 is between 5 and 15 MRayl, ensuring good conductivity and matching effect.

[0085] (c) A third impedance matching layer 43 is made of conductive material on the side of the second impedance matching layer 42 away from the backing 1. The acoustic impedance of the third impedance matching layer 43 is between 2-5 MRayl to ensure good conductivity and matching effect.

[0086] (3) An electromagnetic shielding film 6 is made of conductive material on the side of the matching layer 4 away from the backing 1, that is, on the upper surface of the third impedance matching layer 43. The electromagnetic shielding film 6 includes a main body arranged on the third impedance matching layer 43 and an extension portion extending toward the matching layer 4. An insulating layer is arranged between the extension portion and the matching layer. Finally, the extension portion is contact-connected with the negative electrode on the flexible printed circuit board 8.

[0087] In this embodiment, the method may further include step (4) of manufacturing a lens layer 7 on a side of the electromagnetic shielding film 6 away from the backing 1 , that is, on the upper surface of the electromagnetic shielding film 6 .

[0088] In summary, the present invention adopts a lamination process to increase the sensitivity of the transducer, and adopts a special electrode manufacturing method to ensure that the positive and negative electrodes are conveniently and stably led out; a multi-layer matching process is adopted to ensure the acoustic matching effect of the transducer, and at the same time can significantly improve the signal transmission efficiency and image quality of the transducer, and improve the electroacoustic conversion efficiency of the transducer; a special negative electrode lead-out method is adopted to avoid the introduction of negative electrode copper foil, reduce the cutting difficulty, and simplify the manufacturing process.

[0089] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An ultrasonic transducer, characterized in that: include: Backing; a piezoelectric crystal layer, the piezoelectric crystal layer being disposed on the backing; A matching layer, wherein the matching layer is disposed on a surface of the piezoelectric crystal layer away from the backing; Among them, the piezoelectric crystal layer includes a first piezoelectric crystal layer and a second piezoelectric crystal layer, the first piezoelectric crystal layer is provided with a first electrode and a second electrode, the second piezoelectric crystal layer is provided with a third electrode and a fourth electrode, the first piezoelectric crystal layer and the second piezoelectric crystal layer are coupled to each other, the first electrode and the third electrode are connected to form a positive electrode, the second electrode and the fourth electrode are connected to form a negative electrode, the positive electrode and the negative electrode are isolated from each other, and one of the positive electrode or the negative electrode is electrically connected to the flexible printed circuit board through the matching layer.

2. The ultrasonic transducer according to claim 1, characterized in that: The first piezoelectric crystal layer comprises a first main surface, a second main surface, a first side surface, and a second side surface, the first main surface and the second main surface are arranged opposite to each other, the first side surface and the second side surface are arranged opposite to each other and the first side surface and the second side surface connect the first main surface and the second main surface, the first electrode is arranged on the first main surface, the first side surface, and the second main surface, the second electrode is arranged on the first main surface, the second side surface, and the second main surface, a first notch is arranged on the first main surface, a second notch is arranged on the second main surface, and the first electrode and the second electrode are spaced apart by the first notch and the second notch; The second piezoelectric crystal layer includes a third main surface, a fourth main surface, a third side surface, and a fourth side surface, the third main surface and the fourth main surface are arranged opposite to each other, the third side surface and the fourth side surface are arranged opposite to each other and the third side surface and the fourth side surface are connected to each other, the third electrode is arranged on the third main surface, the third side surface and the fourth main surface, the fourth electrode is arranged on the third main surface, the fourth side surface and the fourth main surface, a third notch is arranged on the third main surface, a fourth notch is arranged on the fourth main surface, and the third electrode and the fourth electrode are spaced apart by the third notch and the fourth notch; The second main surface of the first piezoelectric crystal layer and the third main surface of the second piezoelectric crystal layer are coupled to each other, the second notch and the third notch are opposite to each other, the first electrode and the third electrode are connected to form a positive electrode, the second electrode and the fourth electrode are connected to form a negative electrode, and the positive electrode and the negative electrode are isolated from each other.

3. The ultrasonic transducer according to claim 1, characterized in that: The matching layer includes a first impedance matching layer, which is arranged on a surface of the piezoelectric crystal layer away from the backing, the acoustic impedance of the first impedance matching layer is between 15-20 MRayl, a conductive layer is provided on the first impedance matching layer, and the negative electrode is electrically connected to the flexible printed circuit board through the conductive layer on the first matching layer.

4. The ultrasonic transducer according to claim 3, characterized in that: The matching layer includes a second impedance matching layer, which is arranged on a surface of the first impedance matching layer away from the backing, the acoustic impedance of the second impedance matching layer is between 5-15 MRayl, the second impedance matching layer is made of conductive material, and the second impedance matching layer is electrically connected to the conductive layer.

5. The ultrasonic transducer according to claim 4, characterized in that: The matching layer includes a third impedance matching layer, which is arranged on a surface of the second impedance matching layer away from the backing, the acoustic impedance of the third impedance matching layer is between 2-5 MRayl, the third impedance matching layer is made of conductive material, and the third impedance matching layer is electrically connected to the second impedance matching layer.

6. The ultrasonic transducer according to claim 5, characterized in that: It also includes an electromagnetic shielding film, which is arranged on a side of the third impedance matching layer away from the backing, is made of a conductive material, and electrically connects the third impedance matching layer and the flexible printed circuit board.

7. The ultrasonic transducer according to claim 6, characterized in that: A lens layer is also included, and the lens layer is disposed on a side of the electromagnetic shielding film away from the backing.

8. A method for manufacturing an ultrasonic transducer as claimed in claims 1 to 7, characterized in that: The steps include: (1) forming a piezoelectric crystal layer on a backing, wherein the preparation of the piezoelectric crystal layer comprises the following steps: Prepare a first piezoelectric crystal layer, form an electrode material layer on a first main surface, a second main surface, a first side surface, and a second side surface of the first piezoelectric crystal layer, form a first notch on the first main surface, and form a second notch on the second main surface, so as to divide the electrode material layer into a first electrode and a second electrode isolated from each other; preparing a second piezoelectric crystal layer, forming an electrode material layer on a third main surface, a fourth main surface, a third side surface, and a fourth side surface of the second piezoelectric crystal layer, forming a third notch on the third main surface, and forming a fourth notch on the fourth main surface, so as to divide the electrode material layer into a third electrode and a fourth electrode isolated from each other; The second main surface of the first piezoelectric crystal layer and the third main surface of the second piezoelectric crystal layer are coupled to each other, the second notch and the third notch are opposite to each other, the first electrode and the third electrode are connected to form a positive electrode, the second electrode and the fourth electrode are connected to form a negative electrode, and the positive electrode and the negative electrode are isolated from each other. (2) forming a matching layer on a surface of the piezoelectric crystal layer away from the backing, wherein the matching layer is electrically connected to the negative electrode; (3) The matching layer is electrically connected to the flexible printed circuit board.

9. The method for manufacturing an ultrasonic transducer according to claim 8, characterized in that: The step (2) specifically includes the following steps: (a) forming a first impedance matching layer on a surface of the piezoelectric crystal layer away from the backing, wherein the acoustic impedance of the first impedance matching layer is between 15 and 20 MRayl, and forming a conductive layer on the first impedance matching layer, wherein the conductive layer is electrically connected to the negative electrode; (b) a second impedance matching layer is made of a conductive material on a side of the first impedance matching layer away from the backing, wherein the acoustic impedance of the second impedance matching layer is between 5 and 15 MRayl; (c) A third impedance matching layer is made of conductive material on a side of the second impedance matching layer away from the backing, and the acoustic impedance of the third impedance matching layer is between 2-5 MRayl.

10. The method for manufacturing an ultrasonic transducer according to claim 8, characterized in that: The method also includes the following steps: using a conductive material to make an electromagnetic shielding film on a side of the matching layer away from the backing, and the matching layer is electrically connected to the flexible printed circuit board through the electromagnetic shielding film.

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