A flexible ultrasonic transducer

Abstract

This application relates to the field of ultrasonic transducer technology, specifically a flexible ultrasonic transducer. The flexible ultrasonic transducer provided in this application includes: a flexible circuit board; one surface of the flexible circuit board includes an array of conductive pads connecting circuit layers in the flexible circuit board; a conductive backing layer disposed on the surface of the flexible circuit board on the side where the conductive pads are disposed; a piezoelectric layer disposed on the surface of the conductive backing layer facing away from the flexible circuit board; the conductive backing layer and the piezoelectric layer constitute an initial ultrasonic stack; a plurality of orthogonal first dividing slots, the first dividing slots dividing the initial ultrasonic stack composed of the piezoelectric layer and the conductive backing layer into a plurality of arrayed ultrasonic elements; each ultrasonic element corresponds one-to-one with a conductive pad; the first dividing slots at least expose the surface of the flexible circuit board; a flexible insulating filling layer fills the first dividing slots; the hardness of the flexible insulating filling layer is less than the hardness of the piezoelectric layer and less than the hardness of the conductive backing layer. The flexible ultrasonic transducer provided in this application has a small area for each element, a large number of elements of the same area, and good flexibility.

Description

Technical Field

[0001] This application relates to the field of ultrasonic transducer technology. Specifically, it relates to a flexible ultrasonic transducer. Background Technology

[0002] Currently, wearable ultrasonic sensor products have transitioned from the conceptual stage to the marketization stage of mature products. More and more products with monitoring and diagnostic functions are emerging. However, the ultrasonic transducers on which these products are based, such as wearable array ultrasonic transducers in the laboratory, have a large area, large individual array elements, and poor flexibility, so their practicality is not ideal.

[0003] Therefore, a solution is needed to address the problems of large area, large individual array elements, poor flexibility, and unsatisfactory practicality of wearable ultrasonic transducers. Summary of the Invention

[0004] Therefore, this application provides a flexible ultrasonic transducer to solve the problems of large area, large single array element, poor flexibility, and unsatisfactory practicality of wearable ultrasonic transducers.

[0005] In one aspect of this application, a flexible ultrasonic transducer is provided, comprising:

[0006] Flexible circuit board; one side surface of the flexible circuit board includes an array of conductive pads that connect to the circuit layers in the flexible circuit board.

[0007] A conductive backing layer is disposed on the surface of the flexible circuit board on the side where the conductive pads are located.

[0008] A piezoelectric layer is disposed on the surface of the conductive backing layer facing away from the flexible circuit board.

[0009] The conductive backing layer and the piezoelectric layer constitute the initial ultrasonic stack;

[0010] Several orthogonal first dividing slots divide the initial ultrasonic stack consisting of the piezoelectric layer and the conductive backing layer into several arrayed ultrasonic elements; each ultrasonic element corresponds to a conductive pad; the first dividing slots at least expose the surface of the flexible circuit board.

[0011] A flexible insulating filler layer fills the first dividing groove; the hardness of the flexible insulating filler layer is less than the hardness of the piezoelectric layer and less than the hardness of the conductive backing layer.

[0012] The flexible ultrasonic transducer provided in this application divides the piezoelectric layer and the underlying conductive backing layer into ultrasonic array elements through a first dividing groove, and fills them with a flexible insulating filler layer with lower hardness. On the one hand, the initial ultrasonic stack containing the piezoelectric layer and the conductive backing layer can be etched using a semiconductor etching process to form an array of ultrasonic array elements. Due to the use of a semiconductor etching process, the etching precision, i.e., the precision of cutting the array elements, is greatly improved compared to traditional laser printing or physical cutting. Therefore, the area of ​​a single array element can be greatly reduced, thereby greatly increasing the number of array elements in the same area (from 256 array elements to 1024 array elements in the same area), and the area occupied by the number of array elements is also greatly reduced (the area of ​​256 array elements is only 1 / 4 of the original). On the other hand, in traditional designs, the backing layer is usually a solid layer structure. The solid structure of this layer and the conductive materials such as silver paste make the layer less flexible. This application divides the backing layer and piezoelectric layer together into ultrasonic array elements, and fills the gaps with a less rigid insulating material to form a less rigid flexible insulating filling layer, which further reduces the overall layer hardness. This is controlled by a flexible circuit board, and the area of ​​a single array element is greatly reduced. Therefore, the number of array elements in the same area of ​​the ultrasonic transducer increases while the area occupied by the flexible insulating filling layer increases. This does not reduce the conductive transmission capability of the ultrasonic array elements, but improves the flexibility of the overall structure.

[0013] In some embodiments of this application, the flexible circuit board includes a transducer region and connection areas on four sides of the transducer region; the transducer region includes at least a rectangular area with a size greater than 9.6mm × 9.6mm; the arrayed conductive pads are located within the rectangular area; the coverage area of ​​the initial ultrasonic stack coincides with the rectangular area; the conductive pads are arranged in a 32×32 array; the ultrasonic array elements are arranged in a 32×32 array.

[0014] The flexible ultrasonic transducer provided in this application, through the aforementioned size settings, can provide an array of 1024 ultrasonic elements distributed within a minimum area of ​​9.6mm × 9.6mm, significantly increasing the number of ultrasonic elements within the same area (compared to only 256 elements in traditional methods). This improves image clarity and provides higher image resolution.

[0015] In some embodiments of this application, the first dividing groove also partially extends into the flexible circuit board; the first dividing groove avoids the conductive pads; the depth of the first dividing groove extending into the flexible circuit board is 12μm~30μm.

[0016] The flexible ultrasonic transducer provided in this application has a first segmented groove that extends deep into the flexible circuit board. On the one hand, this ensures that the backing layer is completely etched through, ensuring that the array elements are completely independent of each other. On the other hand, it transforms the planar surface of the flexible circuit board into a concave-convex surface, making it easier to achieve flexible bending, thereby further improving the overall structural flexibility.

[0017] In some embodiments of this application, it also includes:

[0018] The upper electrode layer covers at least the transducer area, the flexible insulating filler layer, and all ultrasonic elements;

[0019] A matching layer is disposed on the surface of the initial upper electrode layer facing away from the flexible circuit board. The outer edge of the matching layer in the projection area of ​​the flexible circuit board coincides with the boundary of the rectangular area.

[0020] The second dividing groove at least partially overlaps with the first dividing groove in one direction, dividing the matching layer and the upper electrode layer into several parallel layer structures.

[0021] The flexible ultrasonic transducer provided in this application divides the matching layer and the upper electrode layer into several parallel strip-shaped layer structures through a second dividing groove, rather than a whole-surface structure, which can further improve the flexibility of the overall transducer structure. The second dividing groove can also be formed by semiconductor etching process, which is compatible with the process of the first dividing groove, and at the same time can achieve higher cutting precision than mechanical cutting or laser printing.

[0022] In some embodiments of this application, the connection area of ​​the flexible circuit board extends from the edge of the transducer area in a direction away from the transducer area; the flexible circuit board is provided with a plurality of external connection pads at the end of the connection area away from the transducer area; the upper electrode layer is connected to the external connection pads of the connection area at least at both ends of the transducer area in one direction.

[0023] In some embodiments of this application, a single connection region has 256 external connection pads;

[0024] Flexible circuit boards can be single-layer or multi-layer circuit boards, including single-layer circuit layers or interconnected multi-layer circuit layers.

[0025] In some embodiments of this application, it also includes:

[0026] A flexible lens layer is disposed on the side of the matching layer away from the flexible circuit board; the flexible lens layer is also filled with a second dividing groove and is integrated with the flexible insulating filling layer.

[0027] An encapsulation layer is disposed on one side of the conductive backing layer.

[0028] The flexible ultrasonic transducer provided in this application encapsulates the top and bottom surfaces of the ultrasonic transducer with a flexible lens layer and an encapsulation layer. It can be formed using an insulating material that is closer to human skin, making the device surface more suitable for contact with human skin and less likely to cause allergic reactions. Furthermore, it can be encapsulated with a flexible material that has a lower hardness than the piezoelectric layer and backing layer, ensuring the overall flexibility of the transducer structure.

[0029] In some embodiments of this application, in the horizontally orthogonal first and second directions, the spacing between the center points of adjacent ultrasonic array elements in the first direction is N mm, and the spacing between the center points of adjacent ultrasonic array elements in the second direction is N mm, where 0.3 ≤ N ≤ 0.5; the size of a single ultrasonic array element is 100 μm × 100 μm to 290 μm × 290 μm; the width of the first dividing slot is 20 μm to 100 μm; and the size of the rectangular region is 100 mm. 2 ~300mm 2 The thickness of the piezoelectric layer depends on the operating frequency of the ultrasonic transducer. The higher the operating frequency, the smaller the thickness of the piezoelectric layer: the thickness of the piezoelectric layer is 0.08mm~1.5mm; the thickness of the flexible ultrasonic transducer is less than 3mm.

[0030] In some embodiments of this application, the piezoelectric layer includes a piezoelectric material layer and piezoelectric electrodes on the upper and lower surfaces of the piezoelectric material layer; the piezoelectric electrodes include gold electrodes or silver electrodes.

[0031] In some embodiments of this application, the main material of the piezoelectric layer includes piezoelectric ceramic; the material of the conductive backing layer includes epoxy-based conductive silver paste; the upper electrode layer includes a gold-plated copper layer; the material of the flexible insulating filler layer includes PDMS; the material of the flexible lens layer includes PDMS or medical rubber; and the material of the encapsulation layer includes PDMS or medical rubber. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a top view schematic diagram of a flexible ultrasonic transducer according to an embodiment of this application;

[0034] Figure 2a This is a partial cross-sectional structural diagram of the array element rows and columns in a flexible ultrasonic transducer according to an embodiment of this application.

[0035] Figure 2b This is a partial cross-sectional structural diagram of the array element row-column spacing in a flexible ultrasonic transducer according to an embodiment of this application.

[0036] Figure 3 This is a three-dimensional structural diagram of a flexible ultrasonic transducer according to an embodiment of this application;

[0037] Figure 4This is a schematic diagram showing the connection between the upper electrode layer and the external connection pad in a flexible ultrasonic transducer according to an embodiment of this application.

[0038] Figure 5 This is a process flow diagram of the core structure in the manufacturing method of a flexible ultrasonic transducer according to an embodiment of this application. Detailed Implementation

[0039] As mentioned earlier, an existing wearable ultrasonic transducer has a large area, large individual array elements, poor flexibility, and is not ideal in terms of practicality.

[0040] To address the aforementioned problems, this application provides a flexible ultrasonic transducer, comprising: a flexible circuit board; one side surface of the flexible circuit board includes an array of conductive pads connecting circuit layers in the flexible circuit board; a conductive backing layer disposed on the side surface of the flexible circuit board where the conductive pads are disposed; a piezoelectric layer disposed on the side surface of the conductive backing layer facing away from the flexible circuit board; the conductive backing layer and the piezoelectric layer constitute an initial ultrasonic stack; a plurality of orthogonal first dividing slots, the first dividing slots dividing the initial ultrasonic stack composed of the piezoelectric layer and the conductive backing layer into a plurality of arrayed ultrasonic elements; the ultrasonic elements correspond one-to-one with the conductive pads; the first dividing slots at least expose the surface of the flexible circuit board; a flexible insulating filling layer filling the first dividing slots; the hardness of the flexible insulating filling layer is less than the hardness of the piezoelectric layer and less than the hardness of the conductive backing layer.

[0041] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In the description of this application, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] Example 1

[0043] refer to Figures 1-4 This embodiment provides a flexible ultrasonic transducer, comprising:

[0044] Flexible circuit board 100; one side surface of flexible circuit board 100 includes an array of conductive pads that connect to the circuit layers in flexible circuit board 100 (circuit layers and conductive pads are not shown in the figure).

[0045] A conductive backing layer 200 is disposed on the surface of the flexible circuit board 100 on the side where the conductive pads are disposed.

[0046] A piezoelectric layer 300 is disposed on the surface of the conductive backing layer 200 facing away from the flexible circuit board 100.

[0047] The conductive backing layer 200 and the piezoelectric layer 300 constitute the initial ultrasonic stack;

[0048] Several orthogonal first dividing slots ( Figure 2a The first dividing groove divides the stacked structure of the piezoelectric layer 300 and the conductive backing layer 200 into several arrayed ultrasonic array elements A; each ultrasonic array element A corresponds to a conductive pad; the first dividing groove exposes at least the surface of the flexible circuit board 100.

[0049] The flexible insulating filler layer 400 fills the first dividing groove; the hardness of the flexible insulating filler layer 400 is less than the hardness of the piezoelectric layer 300 and less than the hardness of the conductive backing layer 200.

[0050] The flexible ultrasonic transducer provided in this embodiment divides the piezoelectric layer 300 and the conductive backing layer 200 below it into ultrasonic array elements A through a first dividing groove, and fills them with a flexible insulating filler layer 400 with lower hardness. On the one hand, the initial ultrasonic stack including the piezoelectric layer 300 and the conductive backing layer 200 can be etched using a semiconductor etching process to form an array of ultrasonic array elements A. Due to the use of a semiconductor etching process, the etching precision, that is, the precision of cutting the ultrasonic array elements A, is greatly improved compared with the laser printing or physical cutting of traditional processes. Therefore, the area of ​​a single ultrasonic array element A can be greatly reduced, thereby greatly increasing the number of array elements in the same area (from 256 array elements to 1024 array elements in the same area), and the area occupied by the number of array elements is also greatly reduced (the area of ​​256 array elements is only 1 / 4 of the original). On the other hand, in traditional designs, the backing layer (corresponding to the conductive backing layer 200 in this embodiment) is usually a solid layer structure. The solid structure of this layer and the conductive materials such as silver paste make the layer less flexible. This application utilizes a semiconductor etching process to cut the backing layer and piezoelectric layer 300 together into ultrasonic array elements A. The gaps are filled with a less rigid insulating material, forming a flexible insulating filler layer with even lower rigidity. This further reduces the overall layer rigidity and is controlled by the flexible circuit board 100. Furthermore, the area of ​​a single ultrasonic array element A is significantly reduced, thus increasing the number of array elements within the same area of ​​the ultrasonic transducer while simultaneously increasing the area occupied by the flexible insulating filler layer 400. This approach does not reduce the conductivity of the ultrasonic array element A while improving the overall structural flexibility. For example, the insulating material can be PDMS, which typically has a rigidity less than Shore 60 HA, while the backing layer typically has a rigidity greater than Shore 45HD and a much lower flexibility than PDMS.

[0051] Further reference Figure 1 and Figure 3In some embodiments of this application, the flexible circuit board 100 includes a transducer region 110 and connection regions 120 on the four sides of the transducer region 110; the transducer region 110 includes at least a rectangular region 111 with dimensions greater than 9.6mm × 9.6mm; an array of conductive pads is located within the rectangular region; the coverage area of ​​the initial ultrasonic stack coincides with the rectangular region 111; the conductive pads are arranged in a 32×32 array; and the ultrasonic array elements A are arranged in a 32×32 array. It should also be noted that the arrayed ultrasonic array elements A are essentially distributed throughout the entire rectangular region 111. Figure 1 For simplicity, only a portion of the ultrasound array element A is shown in the image; this does not mean that ultrasound array element A is concentrated only on one side of the rectangular region 111. Additionally, the dotted lines in the image are merely delineations of regions and do not represent actual structural elements.

[0052] The flexible ultrasonic transducer provided in this embodiment, through the aforementioned size settings, can provide an array of 1024 ultrasonic elements A distributed within a minimum area of ​​9.6mm × 9.6mm, significantly increasing the number of ultrasonic elements A within the same area (compared to only 256 elements in the traditional method). This improves image clarity and results in higher image resolution.

[0053] Furthermore, in some embodiments of this application, the first dividing groove also partially extends into the flexible circuit board 100; the first dividing groove avoids the conductive pads; the depth of the first dividing groove extending into the flexible circuit board 100 is 12μm~30μm.

[0054] The flexible ultrasonic transducer provided in this embodiment has a first segmented groove that extends deep into the flexible circuit board 100. This ensures, on the one hand, that the backing layer is completely etched through, guaranteeing complete independence between the ultrasonic array elements A; on the other hand, it transforms the planar surface of the flexible circuit board 100 into a surface with uneven surfaces (e.g., Figure 2a The surface of the flexible circuit board 100 shown is more easily bent, thereby further improving the flexibility of the overall structure.

[0055] Furthermore, in some embodiments of this application, it also includes:

[0056] Upper electrode layer 500; Upper electrode layer 500 at least covers transducer region 110, flexible insulating filler layer 400 and all ultrasonic array elements A;

[0057] A matching layer 600 is disposed on the surface of the upper electrode layer 500 facing away from the flexible circuit board 100. The outer edge of the projection area of ​​the matching layer 600 on the flexible circuit board coincides with the boundary of the rectangular area 111.

[0058] Second dividing groove ( Figure 2aThe second dividing groove (the gap between the matching layer 600 and the upper electrode layer 500 above adjacent ultrasonic array elements A) at least partially overlaps with the first dividing groove in one direction, dividing the matching layer 600 and the upper electrode layer 500 into several parallel strip-shaped layer structures. That is, the upper electrode layer 500 is composed of several parallel strip-shaped layer structures, and the matching layer 600 is also composed of several parallel strip-shaped layer structures.

[0059] The flexible ultrasonic transducer provided in this embodiment divides the matching layer 600 and the upper electrode layer 500 into several parallel strip-shaped layer structures through a second dividing groove, rather than a whole-surface structure, which can further improve the flexibility of the overall transducer structure. The second dividing groove can also be formed by semiconductor etching process, which is compatible with the process of the first dividing groove, and can achieve higher cutting accuracy compared with mechanical cutting or laser printing. In addition, in actual process, since the product processing size is basically in the tens or hundreds of micrometers, the diamond blade scribing process of semiconductor scribing process can also be used for grooving.

[0060] Furthermore, in some embodiments of this application, the connection area 120 of the flexible circuit board 100 extends from the edge of the transducer region 110 in a direction away from the transducer region 110; the flexible circuit board 100 has a plurality of external connection pads at the ends of the connection area 120 away from the transducer region 110; the upper electrode layer 500 connects at least the external connection pads 121 of the connection area 120 at both ends in one direction of the transducer region 110. The external connection pads 121 are used for connection with external devices. The connection state of the upper electrode layer 500 with the external connection pads 121 is referenced. Figure 4 As shown in the figure. It should be noted that the upper electrode layer 500 outside the rectangular area is not suspended, but is filled and supported by filler adhesive between it and the flexible circuit board 100, which is not shown in the figure. During the manufacturing process, the filler adhesive around the perimeter can be formed first, then the initial upper electrode layer can be laid, and the upper electrode layer 500 can be connected to the external connection pads 121 one by one, and then it can be divided.

[0061] Furthermore, in some embodiments of this application, the number of external connection pads 121 of a single connection area 120 is 256;

[0062] The flexible circuit board 100 is a single-layer circuit board or a multi-layer circuit board, including a single-layer circuit layer or multiple interconnected circuit layers.

[0063] Furthermore, in some embodiments of this application, it also includes:

[0064] The flexible lens layer 700 is disposed on the side of the matching layer 600 away from the flexible circuit board 100; the flexible lens layer 700 is also filled with a second dividing groove and is integrated with the flexible insulating filling layer 400.

[0065] The encapsulation layer 800 is disposed on the side of the flexible circuit board 100 opposite to the conductive backing layer 200.

[0066] The ultrasonic transducer provided in this embodiment encapsulates its top and bottom surfaces with a flexible lens layer 700 and an encapsulation layer 800. This allows the use of an insulating material that is closer to human skin, making the device surface more suitable for contact with human skin and reducing the likelihood of allergic reactions. Furthermore, the encapsulation can be achieved using a material with a hardness lower than that of the piezoelectric layer 300 and good flexibility in the backing layer, ensuring the overall flexibility of the transducer structure.

[0067] Furthermore, in some embodiments of this application, in the horizontally orthogonal first and second directions, the spacing between the center points of adjacent ultrasonic array elements in the first direction is N mm, and the spacing between the center points of adjacent ultrasonic array elements in the second direction is N mm, where 0.3 ≤ N ≤ 0.5; the size of a single ultrasonic array element A is 100 μm × 100 μm to 290 μm × 290 μm; the width of the first dividing slot is 20 μm to 100 μm; and the size of the rectangular region 111 is 100 mm. 2 ~300mm 2 The thickness of the piezoelectric layer 300 depends on the operating frequency of the ultrasonic transducer. The higher the operating frequency, the smaller the thickness of the piezoelectric layer 300: the thickness of the piezoelectric layer 300 is 0.08mm~1.5mm; the thickness of the flexible ultrasonic transducer is less than 3mm.

[0068] For different widths N of the first dividing slot, that is, different spacing N of the ultrasonic array elements A, the dimensions of the rectangular region 111 have the following relationship:

[0069] N=0.3, the area of ​​the rectangular region is approximately 100mm². 2 N=0.4, the area of ​​the rectangular region is approximately 200 mm². 2 N=0.5, the area of ​​the rectangular region is approximately 400 mm². 2 .

[0070] The width of the first dividing groove is limited by the spacing of the conductive pads on the flexible circuit board 100. Typically, since the spacing of the conductive pads is not less than 0.3 mm, the width of the first dividing groove is also not less than 0.3 mm, meaning the width of the ultrasonic element A is not less than 0.3 mm. If the width of the first dividing groove is greater than 0.5 mm, it will affect the overall device size, and furthermore, it will easily etch the conductive pads during the downward etching process.

[0071] The thickness of the piezoelectric layer 300 is related to the operating frequency required by the flexible ultrasonic transducer, as follows:

[0072] For 1MHz, a thickness of 1.35mm~1.45mm is selected; for 7.5MHz, 0.18mm~0.22mm is selected; and for 15MHz, 0.088mm~0.1mm is selected. Because the core piezoelectric layer is thin enough, the overall thickness of the final flexible ultrasonic transducer can be guaranteed to be less than 3mm.

[0073] Furthermore, in some embodiments of this application, the piezoelectric layer 300 includes a piezoelectric material layer and piezoelectric electrodes on the upper and lower surfaces of the piezoelectric material layer; the piezoelectric electrodes include gold electrodes or silver electrodes.

[0074] Furthermore, in some embodiments of this application, the main material of the piezoelectric layer 300 includes piezoelectric ceramics, such as a lead zirconate titanate film; the material of the conductive backing layer 200 includes epoxy-based conductive silver paste; the material of the matching layer 600 includes epoxy resin-based or polyurethane-based composite materials; the upper electrode layer 500 includes a gold-plated copper layer; the material of the flexible insulating filler layer 400 includes PDMS; the material of the flexible lens layer 700 includes PDMS or medical rubber; and the material of the encapsulation layer 800 includes PDMS or medical rubber.

[0075] refer to Figure 5 The flexible ultrasonic transducer provided in this embodiment can be formed by the following method and process, which includes at least the following steps:

[0076] A flexible circuit board 100 is provided; one side surface of the flexible circuit board 100 includes an array of conductive pads that connect to the circuit layers in the flexible circuit board 100 (the circuit layers and conductive pads are not shown in the figure).

[0077] A conductive backing layer 200 is formed on the surface of the flexible circuit board 100 on the side where conductive pads are provided;

[0078] A piezoelectric layer 300 is formed on the surface of the conductive backing layer 200 facing away from the flexible circuit board 100.

[0079] The conductive backing layer 200 and the piezoelectric layer 300 constitute the initial ultrasonic stack;

[0080] Using semiconductor grooving technology, several orthogonal first dividing grooves are formed ( Figure 2a The first dividing groove divides the stacked structure of the piezoelectric layer 300 and the conductive backing layer 200 into several arrayed ultrasonic array elements A, exposing at least the surface of the flexible circuit board 100; the ultrasonic array elements A correspond one-to-one with the conductive pads.

[0081] In actual manufacturing processes, the etching steps using semiconductor etching processes include: laser etching, wet etching, dry etching, and / or photolithography. Laser etching, for example, involves laser ablation cutting of the removal area; wet etching, for example, involves chemical etching of the removal area using an etchant; and dry etching, for example, involves plasma vapor deposition (PVD) etching of the removal area.

[0082] The flexible ultrasonic transducer provided in this embodiment can use etching processes applicable to most semiconductors for cutting array elements. Compared with traditional laser printing or mechanical cutting processes, it can achieve finer and smaller size-level cutting, thereby achieving a smaller area for a single array element and more array elements within the same area.

[0083] Insulating material is filled into the first dividing groove to form a flexible insulating filling layer 400; the hardness of the flexible insulating filling layer 400 is less than the hardness of the piezoelectric layer 300 and less than the hardness of the conductive backing layer 200.

[0084] A specific production process is as follows:

[0085] S01: The flexible circuit board 100, the conductive backing layer 200, and the piezoelectric layer 300 are stacked together in sequence, ensuring that the four sides of the piezoelectric layer 300 and the conductive backing layer 200 are aligned with the rectangular area 111 of the flexible circuit board 100. The piezoelectric layer 300 and the conductive backing layer 200 constitute the initial ultrasonic stack.

[0086] S02: The initial ultrasonic stack is divided into 1024 independent ultrasonic array elements A using a semiconductor etching process. The etching depth is 12μm~30μm deep into the flexible circuit board 100, without penetrating the flexible circuit board 100. The etching position forms the first dividing groove.

[0087] S03: PDMS (polydimethylsiloxane) is filled into the first dividing groove to form a flexible insulating filling layer 400.

[0088] S04: A gold-plated copper foil and a matching layer are stacked on the piezoelectric layer as the initial upper electrode layer 500 and the initial matching layer 600, ensuring that the initial upper electrode layer 500 and the initial matching layer 600 are aligned with the four sides of the cut ultrasonic stack.

[0089] S05: The gold-plated copper foil is soldered to the external connection pads of the connection area 120 of the flexible circuit board 100 away from the transducer area 110 along one direction of the rectangular area 111.

[0090] S06: Using a semiconductor etching process, the initial matching layer 600 and the gold-plated copper foil (initial upper electrode layer 500) are radially divided into several parallel strip-shaped layer structures at a spacing of 0.3×n (n=1,2,3,4) mm. A second dividing groove is formed at the etching location. It should be noted that the spacing between the cut upper electrode layer 500 and matching layer 600 can differ from the spacing of the underlying piezoelectric layer, depending on the required product flexibility; the larger n is, the lower the flexibility.

[0091] S06: A flexible lens layer 700 is formed on the surface of the matching layer 600 facing away from the flexible circuit board 100; the flexible lens layer 700 is also filled with a second dividing groove and is integrated with the flexible insulating filling layer 400.

[0092] S07: An encapsulation layer 800 is formed on the surface of the flexible circuit board 100 on the side opposite to the piezoelectric layer 300.

[0093] The flexible ultrasonic transducer is now complete.

[0094] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A flexible ultrasonic transducer, characterized in that, include: Flexible circuit board; One side surface of the flexible circuit board includes an array of conductive pads that connect to the circuit layers in the flexible circuit board. A conductive backing layer is disposed on the surface of the flexible circuit board on the side where the conductive pads are disposed. A piezoelectric layer is disposed on the surface of the conductive backing layer facing away from the flexible circuit board. The conductive backing layer and the piezoelectric layer constitute the initial ultrasonic stack; A plurality of orthogonal first dividing slots divide the initial ultrasonic stack consisting of the piezoelectric layer and the conductive backing layer into a plurality of arrayed ultrasonic elements; each ultrasonic element corresponds one-to-one with a conductive pad; the first dividing slots at least expose the surface of the flexible circuit board. A flexible insulating filler layer fills the first segmented groove; the hardness of the flexible insulating filler layer is less than the hardness of the piezoelectric layer and less than the hardness of the conductive backing layer.

2. The flexible ultrasonic transducer according to claim 1, characterized in that, The flexible circuit board includes a transducer region and connection areas on all four sides of the transducer region; The transducer region includes at least a rectangular area with dimensions greater than 9.6mm × 9.6mm; The conductive pads of the array are located within the rectangular area; The coverage area of ​​the initial ultrasonic stack coincides with the rectangular region; The conductive pads are arranged in a 32×32 array; the ultrasonic array elements are arranged in a 32×32 array.

3. The flexible ultrasonic transducer according to claim 1 or 2, characterized in that, The first dividing groove also extends partially into the flexible circuit board; there is a gap between the first dividing groove and the conductive pad; The first dividing groove penetrates into the flexible circuit board to a depth of 12μm~30μm.

4. The flexible ultrasonic transducer according to claim 2, characterized in that, Also includes: The upper electrode layer at least covers the transducer region, the flexible insulating filler layer, and all the ultrasonic array elements; A matching layer is disposed on the surface of the upper electrode layer facing away from the flexible circuit board, and the outer edge of the matching layer in the projection area of ​​the flexible circuit board coincides with the boundary of the rectangular area. The second dividing groove at least partially overlaps with the first dividing groove in one direction, dividing the matching layer and the upper electrode layer into several parallel layer structures.

5. The flexible ultrasonic transducer according to claim 4, characterized in that, The connection area of ​​the flexible circuit board extends from the edge of the transducer area in a direction away from the transducer area; The flexible circuit board has several external connection pads at the end of the connection area away from the transducer area. The upper electrode layer is connected to the external connection pads of the connection area at least at both ends in one direction of the transducer region.

6. The flexible ultrasonic transducer according to claim 5, characterized in that, The number of external connection pads in a single connection area is 256; The flexible circuit board is a single-layer circuit board or a multi-layer circuit board, including a single-layer circuit layer or multiple interconnected circuit layers.

7. The flexible ultrasonic transducer according to claim 5, characterized in that, Also includes: A flexible lens layer is disposed on the side of the matching layer away from the flexible circuit board; the flexible lens layer is also filled with the second dividing groove and is integrally connected with the flexible insulating filling layer. An encapsulation layer is disposed on one side of the conductive backing layer.

8. The flexible ultrasonic transducer according to claim 4, characterized in that, In the first and second horizontally orthogonal directions, the distance between the center points of adjacent ultrasonic array elements in the first direction is N mm, and the distance between the center points of adjacent ultrasonic array elements in the second direction is N mm, where 0.3≤N≤0.5; The size of a single ultrasonic element is 100μm×100μm to 290μm×290μm; The width of the first dividing groove is 20μm~100μm; The rectangular area has a size of 100mm. 2 ~300mm 2 ; The thickness of the piezoelectric layer depends on the operating frequency of the ultrasonic transducer; the higher the operating frequency, the smaller the thickness of the piezoelectric layer. The thickness of the piezoelectric layer is 0.08 mm to 1.5 mm. The thickness of the flexible ultrasonic transducer is less than 3 mm.

9. The flexible ultrasonic transducer according to claim 1, characterized in that, The piezoelectric layer includes a piezoelectric material layer and piezoelectric electrodes on the upper and lower surfaces of the piezoelectric material layer; The piezoelectric electrode includes a gold electrode or a silver electrode.

10. The flexible ultrasonic transducer according to claim 7, characterized in that, The main material of the piezoelectric layer includes piezoelectric ceramics; The material of the conductive backing layer includes epoxy-based conductive silver paste. The upper electrode layer includes a gold-plated copper layer; The material of the flexible insulating filler layer includes PDMS; The material of the flexible lens layer includes PDMS or medical rubber; The encapsulation layer is made of materials including PDMS or medical rubber.

Images