An array ultrasonic transducer and a method of manufacturing the same

Abstract

The application provides an array ultrasonic transducer, which comprises a backing layer, a piezoelectric layer and a matching layer arranged in sequence, the piezoelectric layer comprises a ground electrode surface arranged on one side surface and a signal electrode surface arranged on the other side surface, the ground electrode surface and the signal electrode surface are respectively provided with electrodes, and the electrodes of the signal electrode surface are cut to form a plurality of array elements; the array ultrasonic transducer further comprises a flexible circuit board, the flexible circuit board is electrically connected with the piezoelectric layer to lead out the array elements of the piezoelectric layer, the flexible circuit board comprises a substrate and electrodes, the electrodes of the flexible circuit board are in a grid shape and protrude relative to the substrate. The application further provides a preparation method of the array ultrasonic transducer, and the array ultrasonic transducer prepared by the method can realize accurate alignment of the array elements and the electrodes on the flexible circuit board, can reduce crosstalk between the array elements, and can realize stable connection of the piezoelectric layer and the flexible circuit board.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ultrasonic imaging technology, in particular to an array ultrasonic transducer and a preparation method thereof. BACKGROUND

[0002] Medical ultrasonic imaging technology mainly transmits ultrasonic waves into human body through an ultrasonic transducer, and performs linear, fan-shaped or other form of scanning. When encountering the interface of two kinds of tissues with different acoustic impedance, the ultrasonic waves are reflected back to be received by the transducer, and are amplified and processed to be displayed on a screen to form a tomographic image of human body, which is called an ultrasonic image for clinical diagnosis. A plurality of continuous ultrasonic images displayed on the screen can observe the dynamic organ activity. Since the depth of the interface of the internal organ tissues is different, the time of receiving the echo is different, and thus the depth of the interface and the shape and size of the organ can be measured.

[0003] The array ultrasonic transducer is a core component in ultrasonic imaging. The array transducer is mainly composed of a plurality of (64, 128, 192, 256,...) independently working ultrasonic elements for transmitting and receiving sound waves. In the prior art, the array elements of the array ultrasonic transducer are usually disconnected by dividing the positive poles of the array elements on a piezoelectric wafer, and the electrodes on the flexible plate are made into a plurality of units with the same spacing as the array elements. Then, the electrodes on the flexible plate and the positive poles of the array elements are aligned and bonded one by one, so that the array elements on the piezoelectric wafer and the motors on the flexible plate are electrically connected by crimping, and the positive poles of the array elements are disconnected one by one, while the ground poles of all the array elements are still connected together and are led out by a wire or a flexible plate.

[0004] However, the array ultrasonic transducer made by the method of the prior art has some problems. During the processing of the piezoelectric wafer and the flexible plate, there are some deformations and precision errors, which may cause the array elements on the piezoelectric wafer and the electrodes on the flexible plate to be not accurately aligned. Moreover, the connection between the piezoelectric wafer and the flexible plate by the prior art is unstable and not reliable, and the connection between the piezoelectric wafer and the flexible plate is easily disconnected. In addition, after the piezoelectric wafer and the flexible plate connected by the prior art are assembled with the matching layer and other components to form an array ultrasonic transducer, there is a large amount of crosstalk between the array elements.

[0005] In the manufacturing of the array ultrasonic transducer, how to effectively lead out a large number of array elements is a bottleneck technology restricting the development of the transducer. The instability of the connection between the piezoelectric wafer and the flexible plate and the crosstalk between the array elements after the components are assembled to form an array ultrasonic transducer by the prior art have a great impact on the performance of the array ultrasonic transducer. SUMMARY

[0006] Therefore, in order to overcome the defects of the prior art, the present application provides an array ultrasonic transducer and a preparation method thereof.

[0007] The array ultrasonic transducer comprises a backing layer, a piezoelectric layer and a matching layer arranged in sequence, the piezoelectric layer comprises a ground electrode surface arranged on one side surface and a signal electrode surface arranged on the other side surface, the ground electrode surface and the signal electrode surface are respectively provided with electrodes, and the electrodes of the signal electrode surface are cut to form a plurality of array elements.

[0008] Further, a flexible circuit board is electrically connected to the piezoelectric layer to lead out the array elements of the piezoelectric layer, the flexible circuit board comprises a substrate and electrodes, the electrodes of the flexible circuit board are arranged on the substrate, and the electrodes of the flexible circuit board are in a grid shape and protrude relative to the substrate.

[0009] The protruding electrodes of the flexible circuit board make the surface of the flexible circuit board uneven, and when the flexible circuit board is bonded to the piezoelectric layer, the protruding electrodes can be more effectively in contact with the array elements of the piezoelectric layer, thereby increasing the reliability of electrical connection. In addition, the recess formed by the area of the surface of the flexible circuit board not covered by the electrodes is conducive to the retention of the bonding material, and the firmness of the bonding can be increased.

[0010] The electrodes of the ground electrode surface are cut to form a plurality of electrode units, and a conductive structure is arranged on the piezoelectric layer to connect the plurality of electrode units of the piezoelectric layer.

[0011] Further, a cutting seam is formed in each array element on the piezoelectric layer, the cutting seam divides the array element into two or more array element units, and the cutting seam extends from the ground electrode surface to the signal electrode surface.

[0012] In some embodiments, an inter-array element cutting seam is formed on the flexible circuit board, the inter-array element cutting seam divides the electrodes of the flexible circuit board, and the inter-array element cutting seam corresponds to the position of the gap formed between the array elements on the piezoelectric layer.

[0013] The grid shape formed by the electrodes on the flexible circuit board includes a circle, an ellipse, a sector or a polygon.

[0014] The present application also provides a preparation method for preparing the array ultrasonic transducer, the preparation method comprises the following steps:

[0015] Preparation of a piezoelectric layer;

[0016] Connecting the piezoelectric layer with a flexible circuit board and a backing layer;

[0017] Cutting the piezoelectric layer and the flexible circuit board to divide array elements;

[0018] The flexible circuit board comprises a substrate and an electrode, the electrode is arranged on the substrate, the electrode is in a mesh shape and protrudes relative to the substrate, the piezoelectric layer comprises a ground electrode surface arranged on one side surface, the ground electrode surface has an electrode, and a conductive structure is arranged on the piezoelectric layer, and the conductive structure is used for connecting the electrode of the ground electrode surface.

[0019] The piezoelectric layer is connected with the flexible circuit board by the preparation method, and then the array element is divided, so that the problem that the electrode of the flexible circuit board cannot be accurately aligned with the array element in the existing bonding process can be avoided.

[0020] Further, after the piezoelectric layer and the flexible circuit board are cut to divide the array element, the method further comprises the following steps of:

[0021] The piezoelectric layer is cut in each array element. By cutting the piezoelectric layer in the middle of the array element, the purity of the vibration of the piezoelectric layer can be maintained.

[0022] Before the piezoelectric layer and the flexible circuit board are cut to divide the array element, the piezoelectric layer is connected with a matching layer.

[0023] Or, after the piezoelectric layer is cut in each array element, the piezoelectric layer is connected with a matching layer.

[0024] The conductive structure can be formed by arranging different conductive materials, and the conductive material can be a conductive copper foil, conductive glue or the like. The specific arrangement mode of the different conductive materials is also different. For example, when the conductive material is a conductive copper foil,

[0025] The conductive structure arranged on the piezoelectric layer comprises the following steps of:

[0026] After the piezoelectric layer is prepared, before the piezoelectric layer is connected with the flexible circuit board and the backing layer;

[0027] The conductive copper foil is arranged on one end or both ends of the piezoelectric layer in the width direction of the piezoelectric layer, the conductive copper foil covers part of the ground electrode surface on one side of the piezoelectric layer and extends to the other side of the piezoelectric layer.

[0028] When the conductive material is conductive glue, the conductive structure arranged on the piezoelectric layer comprises the following steps of:

[0029] After the piezoelectric layer is cut in each array element;

[0030] The insulating material is filled in the cutting seam formed by cutting the piezoelectric layer, and the conductive glue is applied on the piezoelectric layer after the insulating material is solidified, so as to connect the multiple electrode units of the ground electrode surface.

[0031] In summary, the array ultrasonic transducer and the preparation method thereof have the following beneficial effects: the array ultrasonic transducer is provided with the grid-shaped electrodes protruding relative to the substrate on the flexible circuit board, the electrodes can be more effectively contacted with the array elements of the piezoelectric layer, and the reliability of the electrical connection is increased. In addition, the recess formed in the area of the flexible circuit board surface not covered by the electrodes is beneficial to the retention of the adhesive material, and the firmness of the adhesion can be increased.

[0032] Further, the piezoelectric layer is cut in the middle of the array elements, so that the purity of the vibration of the piezoelectric layer is maintained.

[0033] The array ultrasonic transducer prepared by the preparation method of the array ultrasonic transducer provided by the application can accurately align the array elements and the electrodes on the flexible circuit board, and is not affected by the number of array elements. Compared with the prior art, the more array elements of the array ultrasonic transducer, the more accurately the electrodes of the flexible circuit board and the array elements can be aligned by the array ultrasonic transducer prepared by the method, and the connection between the flexible circuit board and the piezoelectric layer is more firm, and the electrical connection is more reliable. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0035] Figure 1 is a structural schematic diagram of the array ultrasonic transducer of the present application;

[0036] Figure 2 is a structural schematic diagram of the array ultrasonic transducer of the present application;

[0037] Figure 3 is a structural schematic diagram of the array ultrasonic transducer of the present application;

[0038] Figure 4 is a structural schematic diagram of another structure of the array ultrasonic transducer of the present application;

[0039] Figure 5 is a structural schematic diagram of the flexible circuit board of the array ultrasonic transducer of the present application;

[0040] Figure 6 is a structural schematic diagram of the piezoelectric layer of the array ultrasonic transducer of the present application;

[0041] Figure 7 is a structural schematic diagram of the flexible circuit board after cutting of the array ultrasonic transducer of the present application.

[0042] Reference signs:

[0043] 1-backing layer; 2-piezoelectric layer; 21-piezoelectric phase; 22-filler phase; 3-matching layer; 31-first matching layer; 32-second matching layer; 33-matching unit; 34-subunit; 4-flexible circuit board; 41-substrate; 42-electrode; 5-conductive copper foil; 6-inter-element cut; 7-intra-element cut. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0045] The array ultrasonic transducer described in the present application has a frequency range of 0.5 MHz to 100 MHz.

[0046] Embodiment 1

[0047] Reference Figures 1-4 The present embodiment provides an array ultrasonic transducer, which comprises a backing layer 1, a piezoelectric layer 2 and a matching layer 3 arranged in sequence.

[0048] The piezoelectric layer 2 comprises a ground electrode surface arranged on one side surface and a signal electrode surface arranged on the other side surface, and the ground electrode surface and the signal electrode surface each have electrodes. The electrodes of the signal electrode surface are cut to form a plurality of elements, and the electrodes of the ground electrode surface are cut to form a plurality of electrode units at the same interval as the elements of the signal electrode surface. A flexible circuit board 4 is arranged to be electrically connected to the piezoelectric layer 2 to lead out the elements of the piezoelectric layer 2. Along the extension direction of the gap formed by the element division, a conductive material is arranged on one end or both ends of the piezoelectric layer 2 to form a conductive structure, and the conductive structure is used to connect the plurality of electrode units of the piezoelectric layer 2. The conductive material described in the present embodiment can be various, including but not limited to conductive copper foil 5 and conductive adhesive. The material forming the piezoelectric layer 2 can be various, such as a piezoelectric material only having a pure piezoelectric phase 21, a 1-3 composite piezoelectric material, or a 2-2 composite piezoelectric material.

[0049] Further, a cut is formed in each element on the piezoelectric layer 2, and the cut divides each element of the piezoelectric layer 2 into two or more element units. The cut is parallel to the gap formed by the element division, and the cut extends from the ground electrode surface to the signal electrode surface.

[0050] In some embodiments, the backing layer 1 is formed with an inter-element cut 6 corresponding to the gap formed by the element division, and the inter-element cut 6 extends from one side surface of the backing layer 1 toward the other side surface of the backing layer 1.

[0051] Referring to the drawings Figure 5 The flexible circuit board 4 includes a substrate 41 and electrodes 42 attached to the surface of the substrate 41, and the electrodes 42 are protruded relative to the substrate 41. Specifically, the electrodes 42 are in a grid shape. The electrodes 42 of the flexible circuit board 4 are divided into a plurality of units with a pitch equal to the pitch of the elements of the piezoelectric layer 2, and the side of the flexible circuit board 4 with the electrodes 42 faces the signal electrode surface of the piezoelectric layer 2 and is connected to the piezoelectric layer 2. Specifically, the electrodes 42 on the flexible circuit board 4 and the plurality of elements on the signal electrode surface are connected in one-to-one correspondence. In order to enable the electrodes in each unit after the electrodes of the flexible circuit board 4 are divided to be connected, the distance between adjacent electrodes 42 on the flexible circuit board 4 in a direction perpendicular to the gap formed by the division of the elements is less than the pitch of the elements.

[0052] The grid shape formed by the electrodes 42 on the flexible circuit board 4 can be various, such as a circular shape, an elliptical shape, a sector shape, or a polygonal shape, or can be an irregular shape. The circular shape described in the embodiment can be a reference circular shape, such as a common circular shape, or can be a substantially circular shape, such as a shape similar to a circular shape. The polygonal shape can be a triangular shape, a square shape, a rectangular shape, or other polygonal shapes. Preferably, the grid shape formed by the electrodes 42 on the flexible circuit board 4 is a relatively regular shape, such as a circular shape, a rectangular shape, a square shape, or the like.

[0053] As shown in the drawings Figure 5 The grid shape formed by the electrodes on the flexible circuit board 4 in the embodiment is a square shape. The side length D of the grid formed by the electrodes 42 is less than the pitch L of the elements, so that the distance between adjacent electrodes 42 on the flexible circuit board 4 in a direction perpendicular to the gap formed by the division of the elements is less than the pitch of the elements.

[0054] In some embodiments, the flexible circuit board 4 and the piezoelectric layer 2 are connected by adhesion. The protrusion of the electrodes 42 relative to the substrate 41 makes the surface of the flexible circuit board 4 uneven, and when the flexible circuit board 4 and the piezoelectric layer 2 are adhered, the protruding electrodes 42 can more effectively contact the elements of the piezoelectric layer 2, increasing the reliability of the electrical connection. In addition, the recess formed by the area of the surface of the flexible circuit board 4 not covered by the electrodes 42 is conducive to the retention of the adhesive material, and can increase the firmness of the adhesion. Therefore, the structure design of the flexible circuit board 4 provided by the embodiment can make the connection between the flexible circuit board 4 and the piezoelectric layer 2 more firm, and improve the reliability of the electrical connection.

[0055] In a specific embodiment, the electrodes are protruded by more than 10 microns relative to the substrate 41.

[0056] The matching layer 3 is arranged on the ground electrode side of the piezoelectric layer 2, and the number of the matching layer 3 can be one or more. The matching layer 3 comprises a plurality of matching units 33, the number of the matching units 33 is the same as the number of the electrode units of the piezoelectric layer 2, the width of the matching units 33 is less than or equal to the width of the electrode units, and the plurality of electrode units and the plurality of matching units 33 are arranged one by one, and the adjacent two matching units 33 are filled with insulating materials to form an insulating layer.

[0057] The matching layer 3 of the array ultrasonic transducer provided in the embodiment comprises a plurality of separated matching units 33, which can reduce the crosstalk between the array elements and reduce the sound. Alternatively, each matching unit 33 can be a one-piece structure or comprise two or more separated sub-units 34, and the sub-units 34 of the matching unit 33 are filled with insulating materials to form an insulating layer. The number of the sub-units 34 of the matching unit 33 is the same as the number of the array element units in the array element, and the sub-units 34 are arranged one by one with the array element units.

[0058] In the embodiment, the insulating materials filled between the matching units 33 and the insulating materials filled between the sub-units 34 of the matching unit 33 are both epoxy resins.

[0059] Embodiment 2

[0060] The embodiment provides a preparation method of an array ultrasonic transducer, which is used for preparing the array ultrasonic transducer shown in Embodiment 1.

[0061] S1: preparing a piezoelectric layer 2

[0062] The piezoelectric layer 2 is cut and filled to form a shape with a piezoelectric phase 21 and a filling phase 22. Specifically, the piezoelectric layer 2 is cut and filled to form a structure in which the piezoelectric phase 21 and the filling phase 22 are arranged alternately along the width direction of the piezoelectric layer 2, taking the preparation of the piezoelectric layer 2 from the 1-3 composite piezoelectric material as an example. Figure 6

[0063] The prepared piezoelectric layer 2 comprises a ground electrode surface arranged on one side surface and a signal electrode surface arranged on the other side surface, and the ground electrode surface and the signal electrode surface respectively have electrodes.

[0064] S2: connecting the piezoelectric layer 2 with the matching layer 3, the flexible circuit board 4 and the backing layer 1

[0065] The matching layer 3 is connected on the side where the ground electrode surface of the piezoelectric layer 2 is located, and the flexible circuit board 4 and the backing layer 1 are sequentially connected on the side where the signal electrode surface of the piezoelectric layer 2 is located. The flexible circuit board 4 comprises a substrate 41 and electrodes 42, the electrodes 42 are in a grid shape, the electrodes 42 are attached to the surface of the substrate 41 and the electrodes 42 protrude relative to the substrate 41. The matching layer 3 can be one or more layers. ​

[0066] In the embodiment, the matching layer 3, the flexible circuit board 4 and the backing layer 1 are connected by bonding, and the matching layer 3 includes two layers, i.e., a first matching layer 31 and a second matching layer 32. The electrodes 42 of the flexible circuit board 4 protrude relative to the substrate 41, which makes the surface of the flexible circuit board 4 uneven. When the flexible circuit board 4 is bonded to the piezoelectric layer 2, the protruding electrodes 42 can be more effectively in contact with the elements of the piezoelectric layer 2, thereby increasing the reliability of the electrical connection. In addition, the recess formed in the region of the surface of the flexible circuit board 4 where the electrodes 42 are not present is conducive to the retention of the bonding material, thereby increasing the firmness of the bonding.

[0067] In a specific embodiment, the electrodes protrude by more than 10 microns relative to the substrate 41.

[0068] S3: cutting the matching layer 3, the piezoelectric layer 2 and the flexible circuit board 4 to divide the elements

[0069] According to the preset element spacing, the matching layer 3, the piezoelectric layer 2 and the flexible circuit board 4 formed by the connection are cut in the width direction of the conductive layer to a first preset depth to divide the elements, specifically, cutting from the matching layer 3 to the backing layer 1 to the flexible circuit board 4, and cutting to form an inter-element cut 6. The inter-element cut 6 is filled with an insulating material. In the embodiment, the insulating material filled in the inter-element cut 6 is epoxy resin.

[0070] In the direction perpendicular to the gap formed by the element division, the distance between adjacent electrodes 42 on the flexible circuit board 4 is less than the spacing of the elements. The specific cutting method for dividing the elements includes but is not limited to using a dicing machine or laser processing.

[0071] In some embodiments, in order to facilitate operation, the cutting can be performed to the backing layer 1, i.e., the part of the area of the backing layer 1 is cut when the elements are divided.

[0072] The way provided by the embodiment for dividing the elements can also completely separate the matching layer 3 into multiple matching units 33, thereby reducing the cross talk between the elements. In addition, the way of the embodiment of connecting the piezoelectric layer 2 and the flexible circuit board 4 and then dividing the elements can avoid the problem that the electrodes 42 of the flexible circuit board 4 are misaligned with the elements and cannot be accurately aligned in the existing bonding process. As shown in the drawings, after cutting, the flexible circuit board 4 is divided into multiple units, and the electrodes 42 in each unit are connected. Figure 7

[0073] S4: cutting the matching layer 3 and the piezoelectric layer 2 in each element

[0074] ​In each array element, the matching layer 3 and the piezoelectric layer 2 are cut in the width direction of the conductive layer by a second preset depth, specifically, cut from the matching layer 3 to the piezoelectric layer 2 to the piezoelectric layer 2, to form an array element cut 7. The array element cut 7 is filled with insulating material. In this embodiment, the insulating material filled in the array element cut 7 is epoxy resin.

[0075] Specifically, the cutting to the piezoelectric layer 2 can be cutting through the piezoelectric layer in each array element, or cutting most of the area of the piezoelectric layer 2 but not cutting through the piezoelectric layer 2 when cutting in each array element.

[0076] Specifically, the cutting to the piezoelectric layer 2 can be cutting through the piezoelectric layer in each array element, or cutting most of the area of the piezoelectric layer 2 but not cutting through the piezoelectric layer 2 when cutting in each array element.

[0077] By cutting the piezoelectric layer 2 between the array elements, the purity of the vibration of the piezoelectric layer 2 can be maintained.

[0078] Specifically, the cutting to the piezoelectric layer 2 can be cutting through the piezoelectric layer in each array element, or cutting most of the area of the piezoelectric layer 2 but not cutting through the piezoelectric layer 2 when cutting in each array element.

[0079] In addition, when dividing the array elements, cutting the piezoelectric layer 2 separates the electrodes 42 on the ground electrode surface of the piezoelectric layer 2 into multiple electrode units corresponding to the array elements, and therefore, a conductive structure is needed to connect the multiple electrode units to enable the ground electrodes of all array elements of the piezoelectric layer 2 to be connected and uniformly led out. The conductive structure can be formed by providing different conductive materials, and the conductive materials can be conductive copper foil 5, conductive glue, etc. The specific arrangement of the different conductive materials is also different, for example: when the conductive material is conductive copper foil 5, the arrangement of the conductive material is to cover part of the area of the piezoelectric layer 2 with the conductive copper foil 5 after step S1 is completed, and then step S2 is performed; when the conductive material is conductive glue, the arrangement of the conductive material is to apply the conductive glue to connect the multiple electrode units on the ground electrode surface together after step S4 is completed; and the like. In this embodiment, the matching layer does not completely cover the piezoelectric layer, and part of the area of the ground electrode surface of the piezoelectric layer is exposed, which facilitates the application of the conductive glue to connect the multiple electrode units.

[0080] Referring to Figures 2-4In the present embodiment, the conductive material is formed by disposing a conductive copper foil 5. The conductive material is disposed as follows: after step S1 is completed, the conductive copper foil 5 is overlaid on one end or both ends of the piezoelectric layer 2 along the width direction of the piezoelectric layer 2, the conductive copper foil 5 covers a part of the ground electrode surface and extends to the other side of the piezoelectric layer 2, i.e. extends to the signal electrode surface direction. In order to enable the conductive copper foil 5 to be connected to multiple electrode units after the array elements are divided, the length of the conductive copper foil 5 extending from the ground electrode surface to the signal electrode surface direction is greater than the sum of the slit depths of the array element slits 6 formed on the piezoelectric layer 2 and the backing layer 1. Preferably, the conductive copper foil 5 only covers a very small part of the ground electrode surface, so as to reduce the amount of the conductive copper foil 5 as much as possible while forming a connection with the ground electrode surface.

[0081] The piezoelectric layer 2 connected with the flexible circuit board 4 by the method of the present embodiment can achieve one-to-one accurate alignment of the electrodes 42 of the flexible circuit board 4 and the array elements, and is not affected by the number of array elements. That is, the number of array elements of the array ultrasonic transducer prepared by the method provided by the present embodiment is not limited. Compared with the prior art, the more the array elements of the array ultrasonic transducer, the more advantageous it is to prepare the array ultrasonic transducer by the present method, which is embodied in that the present method can more accurately align the electrodes 42 of the flexible circuit board 4 and the array elements of the piezoelectric layer 2 one-to-one, and the connection between the flexible circuit board 4 and the piezoelectric layer 2 is more firm, and the electrical connection is more reliable.

[0082] Embodiment 3

[0083] The present embodiment provides a method for preparing an array ultrasonic transducer, which is used to prepare the array ultrasonic transducer shown in Embodiment 1.

[0084] S1: preparing a piezoelectric layer 2

[0085] The piezoelectric layer 2 is cut and filled to form a shape having a piezoelectric phase 21 and a filling phase 22. Specifically, in the present embodiment, the piezoelectric layer 2 is cut and filled to form a structure in which the piezoelectric phase 21 and the filling phase 22 are arranged alternately along the width direction of the piezoelectric layer 2, as shown in the drawing. Figure 6

[0086] The prepared piezoelectric layer 2 includes a ground electrode surface arranged on one side surface and a signal electrode surface arranged on the other side surface, and the ground electrode surface and the signal electrode surface each have an electrode.

[0087] S2: connecting the piezoelectric layer 2 with the flexible circuit board 4 and the backing layer 1

[0088] ​The flexible circuit board 4 and the backing layer 1 are connected in sequence on the side of the piezoelectric layer 2 where the signal electrode surface is located. The flexible circuit board 4 includes a substrate 41 and electrodes 42, the electrodes 42 are in a grid shape, the electrodes 42 are attached to the surface of the substrate 41 and the electrodes 42 protrude relative to the substrate 41. The matching layer 3 can be one layer or multiple layers.

[0089] In this embodiment, the flexible circuit board 4 and the backing layer 1 are connected by bonding. The protrusion of the electrodes 42 relative to the substrate 41 makes the surface of the flexible circuit board 4 uneven, and when the flexible circuit board 4 is bonded to the piezoelectric layer 2, the protruding electrodes 42 can more effectively contact the elements of the piezoelectric layer 2, increasing the reliability of the electrical connection. In addition, the recess formed by the area of the surface of the flexible circuit board 4 not covered by the electrodes 42 is conducive to the retention of the bonding material, which can increase the firmness of the bonding.

[0090] In a specific embodiment, the electrodes protrude more than 10 microns relative to the substrate 41.

[0091] S3: Cutting the piezoelectric layer 2 and the flexible circuit board 4 to divide the elements

[0092] According to the predetermined element spacing, the piezoelectric layer 2 and the flexible circuit board 4 formed by the connection are cut in the width direction of the conductive layer to a first predetermined depth to divide the elements, specifically, cutting from the piezoelectric layer 2 to the backing layer 1 to the flexible circuit board 4, cutting to form an inter-element cut 6. In the inter-element cut 6, an insulating material is filled. In this embodiment, the insulating material filled in the inter-element cut 6 is epoxy resin.

[0093] In the direction perpendicular to the gap formed by the element division, the distance between adjacent electrodes 42 on the flexible circuit board 4 is less than the spacing of the elements. The specific cutting method for dividing the elements includes but is not limited to using a dicing machine, laser processing.

[0094] In some embodiments, in order to facilitate operation, the cutting can be cut to the backing layer 1, i.e. the surface layer region of the backing layer 1 is cut when the elements are divided.

[0095] The method of connecting the piezoelectric layer 2 and the flexible circuit board 4 before dividing the elements in this embodiment can avoid the problem that the electrodes 42 of the flexible circuit board 4 are misaligned and cannot be accurately aligned with the elements in the existing bonding process. As shown in the drawings, after cutting, the flexible circuit board 4 is not completely cut through, and the electrodes 42 on the flexible circuit board 4 are still connected to the piezoelectric layer 2. Figure 7

[0096] S4: Cutting the piezoelectric layer 2 in each element

[0097] ​In each array element, the piezoelectric layer 2 is cut along the width direction of the conductive layer to a second preset depth, specifically, cut from the ground electrode surface of the piezoelectric layer 2 to the signal electrode surface, forming an array element cut 7. The array element cut 7 is filled with insulating material. In this embodiment, the insulating material filled in the array element cut 7 is epoxy resin.

[0098] Specifically, the cutting method in each array element includes but is not limited to using a scribe machine, laser processing.

[0099] Specifically, the piezoelectric layer can be cut through in each array element, or a large part of the piezoelectric layer 2 is cut in each array element but not cut through the piezoelectric layer 2.

[0100] By cutting the piezoelectric layer 2 between the array elements, the purity of the piezoelectric layer 2 vibration can be maintained.

[0101] Specifically, after cutting the piezoelectric layer 2 and the flexible circuit board 4 to divide the array elements, the insulating material can be filled in the array element cut 6, then the piezoelectric layer 2 is cut in each array element, and then the insulating material is filled in the array element cut 7. Alternatively, after cutting the piezoelectric layer 2 and the flexible circuit board 4 to divide the array elements, the piezoelectric layer 2 is cut in each array element, and then the insulating material is filled in the array element cut 6 and the array element cut 7.

[0102] S5: connecting the piezoelectric layer 2 with the matching layer 3

[0103] The matching layer 3 is connected on the side where the ground electrode surface of the piezoelectric layer 2 is located. In this embodiment, the matching layer 3 and the piezoelectric layer 2 are connected by adhesion, and the matching layer 3 includes two layers, i.e., a first matching layer 31 and a second matching layer 32.

[0104] In addition, when the array elements are divided, the piezoelectric layer 2 is cut to divide the electrodes 42 on the ground electrode surface of the piezoelectric layer 2 into multiple non-connected electrode units corresponding to the array elements. Therefore, a conductive structure is needed to connect the multiple electrode units so that the ground electrodes of all the array elements of the piezoelectric layer 2 can be connected and uniformly led out. The conductive structure can be formed by setting different conductive materials, which can be conductive copper foil 5, conductive glue, etc. The specific setting method of the different conductive materials is also different. For example, when the conductive material is conductive copper foil 5, the setting method of the conductive material is to cover part of the piezoelectric layer 2 with the conductive copper foil 5 after step S1 is completed, and then step S2 is performed; when the conductive material is conductive glue, the setting method of the conductive material is to apply the conductive glue to connect the multiple electrode units on the ground electrode surface together after step S4 is completed, and then step S5 is performed; and so on.

[0105] The piezoelectric layer 2 connected by the method of the embodiment and the flexible circuit board 4 can realize one-to-one accurate alignment of the electrodes 42 of the flexible circuit board 4 and the array elements, and is not affected by the number of array elements. That is, the number of array elements of the array ultrasonic transducer prepared by the method provided by the embodiment is not limited. Compared with the prior art, the more the array elements of the array ultrasonic transducer, the more advantageous the array ultrasonic transducer prepared by the method is, which is embodied in that the array ultrasonic transducer prepared by the method can more accurately align the electrodes 42 of the flexible circuit board 4 and the array elements of the piezoelectric layer 2 one by one, and the connection between the flexible circuit board 4 and the piezoelectric layer 2 is more firm, and the electrical connection is more reliable.

[0106] In summary, the array ultrasonic transducer provided by the embodiment sets the grid-shaped electrodes protruding relative to the substrate on the flexible circuit board, which can make the electrodes more effectively contact the array elements of the piezoelectric layer, and increase the reliability of the electrical connection. In addition, the recess formed by the area of the flexible circuit board surface not covered by the electrodes is conducive to the retention of the adhesive material, and can increase the firmness of the adhesion.

[0107] Further, the piezoelectric layer is cut in the middle of the array elements, so as to maintain the purity of the vibration of the piezoelectric layer.

[0108] The array ultrasonic transducer prepared by the preparation method of the array ultrasonic transducer provided by the embodiment can accurately align the array elements and the electrodes on the flexible circuit board, and is not affected by the number of array elements. Compared with the prior art, the more the array elements of the array ultrasonic transducer, the more accurately the array ultrasonic transducer prepared by the method can align the electrodes of the flexible circuit board and the array elements one by one, and the connection between the flexible circuit board and the piezoelectric layer is more firm, and the electrical connection is more reliable.

[0109] The above is only the preferred embodiment of the present application, and is not used to limit the present application. In addition to the above embodiments, different variants can also be provided, and the technical features of the above embodiments can be combined with each other. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An array ultrasonic transducer, characterized in that, It includes a backing layer, a piezoelectric layer and a matching layer arranged in sequence. The piezoelectric layer includes a ground electrode surface disposed on one side surface and a signal electrode surface disposed on the other side surface. The ground electrode surface and the signal electrode surface each have an electrode. The electrode of the signal electrode surface is cut to form multiple array elements. It also includes a flexible circuit board electrically connected to the piezoelectric layer to bring out the array elements of the piezoelectric layer. On the piezoelectric layer, each array element has a slit formed, the slit dividing the array element into two or more array element units. The slit extends from the ground electrode surface towards the signal electrode surface and cuts from the matching layer towards the piezoelectric layer. The flexible circuit board includes a substrate and electrodes. The electrodes of the flexible circuit board are disposed on the substrate and are mesh-shaped and protrude relative to the substrate.

2. The array ultrasonic transducer according to claim 1, characterized in that, The electrodes on the ground electrode surface are cut to form multiple electrode units, and a conductive structure is provided on the piezoelectric layer to connect the multiple electrode units of the piezoelectric layer.

3. The array ultrasonic transducer according to claim 1, characterized in that, The flexible circuit board has inter-element slits formed on it, which divide the electrodes of the flexible circuit board. The positions of the inter-element slits correspond to the gaps formed between the elements on the piezoelectric layer.

4. The array ultrasonic transducer according to claim 1, characterized in that, The grid shape formed by the electrodes on the flexible circuit board includes circles, ellipses, fan shapes, or polygons.

5. A method for fabricating an array ultrasonic transducer, used to fabricate the array ultrasonic transducer according to any one of claims 1-4, characterized in that, include: Fabrication of piezoelectric layers; The piezoelectric layer is connected to the flexible circuit board and the backing layer; Cut the piezoelectric layer and the flexible circuit board to divide the array elements; The flexible circuit board includes a substrate and electrodes. The electrodes are disposed on the substrate and are mesh-shaped and protrude relative to the substrate. The piezoelectric layer includes a ground electrode surface disposed on one side surface. The ground electrode surface has electrodes. A conductive structure is disposed on the piezoelectric layer to connect the electrodes of the ground electrode surface.

6. The method for fabricating an array ultrasonic transducer according to claim 5, characterized in that, Following "cutting the piezoelectric layer and the flexible circuit board to divide the array elements", the process also includes: A piezoelectric layer is cut in each of the array elements.

7. The method for fabricating an array ultrasonic transducer according to claim 6, characterized in that, Before "cutting the piezoelectric layer and the flexible circuit board to divide the array elements", the piezoelectric layer is connected to the matching layer; Alternatively, after "cutting the piezoelectric layer in each of the array elements", the piezoelectric layer is connected to the matching layer.

8. The method for fabricating an array ultrasonic transducer according to claim 5, characterized in that, "Setting a conductive structure on the piezoelectric layer" includes: After "preparing the piezoelectric layer" and before "connecting the piezoelectric layer to the flexible circuit board and the backing layer"; A conductive copper foil is applied to one or both ends of the piezoelectric layer along its width direction. The conductive copper foil covers a portion of the ground electrode surface on one side of the piezoelectric layer and extends to the other side of the piezoelectric layer.

9. The method for fabricating an array ultrasonic transducer according to claim 6, characterized in that, "Setting a conductive structure on the piezoelectric layer" includes: After "cutting the piezoelectric layer in each of the array elements"; An insulating material is filled into the slit formed by cutting the piezoelectric layer. After the insulating material is cured, conductive adhesive is applied to the piezoelectric layer to connect the multiple electrode units of the ground electrode surface.

Images