Piezoelectric array element for an ultrasonic transducer and method of manufacturing the same

Abstract

A piezoelectric array element for an ultrasonic transducer and a method of manufacturing the same, comprising the steps of: plating electrodes on both sides of a piezoelectric layer, forming a signal electrode on a side of a transmitting surface and a ground electrode on a side facing away from the transmitting surface, leading the ground electrode out of a backing layer of the piezoelectric array element, providing a conductive matching layer, leading the signal electrode out of a working area of the piezoelectric array element to a position outside the working area, providing a non-piezoelectric material area on the piezoelectric layer, and leading the signal electrode out of the non-piezoelectric material area through the conductive matching layer, wherein a working frequency of the piezoelectric array element is greater than or equal to 20 MHz, and an area of the working area is less than or equal to 1.0 square millimeters; the piezoelectric array element is provided with the non-piezoelectric material area on the piezoelectric layer, and the electrodes are led out to the position outside the non-working area of the piezoelectric array element through the conductive matching layer, so that the influence of the point-coated conductive silver paste on the acoustic performance is eliminated while the effective size of the piezoelectric array element is unchanged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ultrasonic transducers, in particular to a piezoelectric array element for an ultrasonic transducer and a manufacturing method thereof. BACKGROUND

[0002] As an important supplementary means of coronary angiography, IntraVascular Ultrasound (IVUS) improves the accuracy of lesion diagnosis, and has important guiding significance for the strategy, stent selection and effect evaluation of Percutaneous Coronary Intervention (PCI).

[0003] An IVUS system is usually composed of an ultrasonic catheter, a proximal drive module and an ultrasonic imaging system. Among them, the ultrasonic catheter is mainly composed of an ultrasonic transducer, a sheath and a transmission shaft, etc., mainly using the ultrasonic transducer to transmit and receive ultrasonic signals to collect the internal structure information of the blood vessel. The proximal drive module is mainly responsible for the driving control and signal transmission between the ultrasonic catheter and the imaging system. The ultrasonic imaging system is mainly used for data processing and imaging.

[0004] The miniature ultrasonic transducer installed at the distal end of the ultrasonic catheter of the IVUS system is the core component of the IVUS technology. The IVUS system uses the ultrasonic catheter to place the ultrasonic transducer inside the blood vessel to transmit and receive ultrasonic signals, so as to display the cross-sectional image of the blood vessel and the thickness of the blood vessel wall structure, the size and shape of the lumen, etc. in real time, accurately measure the diameter and cross-sectional area of the blood vessel, and even identify calcification, fibrosis and lipid pool, etc. and find early lesions of the blood vessel that cannot be displayed by coronary angiography.

[0005] An IVUS ultrasonic transducer is usually composed of piezoelectric material, backing, matching layer and electrode lead-out structure, and has two types of array and single element. The array transducer uses a cylindrical structure to arrange the elements to realize 360-degree imaging inside the blood vessel. The single-element transducer uses a drive shaft to drive the transducer to rotate to realize 360-degree imaging inside the blood vessel. The smaller the size of the miniature ultrasonic transducer at the distal end of the IVUS ultrasonic catheter, the thinner the blood vessel that can be detected. The single-element transducer can make the size of the transducer very small due to the small number of elements. Usually, the single-element IVUS ultrasonic transducer is a rectangle with a surface length*width less than 1mm*1mm or a circle with a surface diameter less than 1mm, and the center frequency is greater than or equal to 20MHz. Due to the small size and high frequency, the processing of each layer of material and the electrode lead-out of the IVUS ultrasonic transducer are very difficult.

[0006] The current IVUS single-element ultrasonic transducer is mainly realized through the following process steps:

[0007] Step one, double-sided grinding of piezoelectric material to the thickness corresponding to the designed frequency, usually less than 0.1mm;

[0008] Step two, plating electrode layer on both sides of piezoelectric material;

[0009] Step three, pouring conductive backing layer on one side of piezoelectric material;

[0010] Step four, cutting piezoelectric material with plated electrode layer and conductive emitting surface backing into final size;

[0011] Step five, leading out electrode. Ground electrode is led out through conductive backing and communicates with ground wire of coaxial cable; signal electrode is usually led out through conductive material on the edge of piezoelectric material surface plating layer and communicates with signal wire of coaxial cable.

[0012] Step six, depositing matching layer and protective layer on emitting surface of piezoelectric material.

[0013] The above manufacturing process mainly has the following two defects:

[0014] 1) Signal pole leading-out method occupies part of emitting surface, affecting the performance of transducer.

[0015] Since the existing process for manufacturing transducer is to plate electrode layer on piezoelectric material, and then cut piezoelectric material into final size by slitting. In this way, the piezoelectric material of final size forms signal pole plating layer surface and ground plating layer surface, and the two surfaces are not conductive. The electrode leading-out process usually leads out ground pole by pouring conductive backing on one side of piezoelectric material, and leads out signal pole by extending conductive glue on the other side of piezoelectric material plating layer to the outside of piezoelectric material. Since the conductive glue material is different from the impedance of the subsequent deposited matching layer material, and the thickness of the conductive glue material on the signal pole surface is not easy to control, the boundary conditions of piezoelectric material are affected, resulting in the decline of transducer performance and the decline of performance consistency among products.

[0016] 2) The method of leading out electrode and then depositing matching layer and protective layer limits the number of matching layers.

[0017] After piezoelectric material is cut into small rectangular pieces with length and width less than 1mm and electrodes are led out, the piezoelectric material is too small in size and the conductive silver glue points on the signal surface cause the surface to be uneven, so the piezoelectric material cannot be pasted with a matching layer on the emitting surface by means of adhesion. The matching layer material is prone to diffuse to the periphery of the piezoelectric material during pouring, affecting the size of the final transducer, and the thickness of the poured material is not easy to control. The current commonly used method of depositing a matching layer can control the thickness of the deposited material by controlling the power and deposition time of the deposition equipment, but the materials available for deposition are limited, which limits the selection of the transducer matching layer, making it difficult to make a transducer with multiple matching layers. The commonly used deposition material is Parylene-C material (a type of parylene material), which has a sound impedance of less than 3 MRayl, which is quite different from the sound impedance of piezoelectric materials, especially piezoelectric ceramics (which usually have a sound impedance of more than 30 MRayl), so the IVUS ultrasonic transducer has generally low sensitivity and bandwidth. SUMMARY

[0018] In view of the above technical problems, the purpose of the present application is to provide a piezoelectric element for an ultrasonic transducer and a manufacturing method thereof, a non-piezoelectric material region is provided on the piezoelectric layer, and the electrodes are led out to a position outside the non-working region of the piezoelectric element through a conductive matching layer, thereby eliminating the influence of point-coated conductive silver paste on acoustic performance while ensuring the effective size of the piezoelectric element.

[0019] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0020] According to one aspect of the present application, a manufacturing method of a piezoelectric element for an ultrasonic transducer is provided, comprising the steps of:

[0021] electrodes are plated on both sides of the piezoelectric layer, a signal electrode is formed on the emitting surface side, and a ground electrode is formed on the side facing away from the emitting surface, the ground electrode is led out from the backing layer of the piezoelectric element;

[0022] a conductive matching layer is provided, and the signal electrode is led out to a position outside the working region of the piezoelectric element.

[0023] In some specific technical solutions, the method further comprises the step of:

[0024] a non-piezoelectric material region is provided on the piezoelectric layer, and the signal electrode is led out from the non-piezoelectric material region through the conductive matching layer.

[0025] In some preferred technical solutions, the non-piezoelectric material region is provided on the piezoelectric layer in the following manner:

[0026] The piezoelectric material is cut at intervals larger than the designed length of the piezoelectric element, and an insulating material is filled in the cut seam to form the non-piezoelectric material region.

[0027] In some preferred embodiments, the step of forming the piezoelectric layer further comprises:

[0028] After the electrodes are plated on both sides of the piezoelectric layer, the piezoelectric material is cut along the side of the piezoelectric material and the formed insulating strip to separate the insulating material from the piezoelectric material, thereby forming an air gap.

[0029] In some preferred embodiments, the piezoelectric layer is provided with a non-piezoelectric material region in the following manner:

[0030] After the piezoelectric material is cut to form the conductive matching layer, the backing material and the piezoelectric material are cut off along the width direction at the end of the piezoelectric element in the length direction, and the depth of the cut needs to be greater than or equal to the total thickness of the backing layer and the piezoelectric layer.

[0031] In some preferred embodiments, the piezoelectric layer is provided with a non-piezoelectric material region in the following manner:

[0032] After the piezoelectric material is cut along the width direction of the piezoelectric element and the conductive material is filled in the cut, a slot is cut in the backing layer on one side of the piezoelectric element according to the length dimension of the piezoelectric element, and the insulating material is filled in the slot, and the depth of the slot needs to be greater than the sum of the thicknesses of the backing and the piezoelectric material.

[0033] In some preferred embodiments, the step of forming the conductive matching layer comprises:

[0034] One or more conductive strips are cut along the length direction of the piezoelectric element, or one or more conductive strips are cut along the length direction and the width direction of the piezoelectric element, respectively, to form a cross.

[0035] In some preferred embodiments, the conductive strips of the conductive matching layer coincide with the non-piezoelectric material region of the piezoelectric layer.

[0036] In some preferred embodiments, the conductive matching layer is a plurality of layers stacked together, and there is a coinciding part between at least one pair of adjacent conductive matching layers.

[0037] When the signal pole is finally led out from the outer surface of the conductive matching layer, the non-piezoelectric material region corresponding to the outermost conductive matching layer has conductive material;

[0038] When the signal pole is finally led out from the outer surface of the backing layer on the side of the piezoelectric layer away from the matching layer, the non-piezoelectric material region corresponding to at least the innermost conductive matching layer has conductive material.

[0039] In some preferred embodiments, the conductive matching layer is formed by plating a conductive layer on both sides of the matching layer; or,

[0040] The conductive matching layer is made of conductive material.

[0041] In some specific embodiments, the method comprises the following specific steps:

[0042] The piezoelectric layer is made:

[0043] The piezoelectric material is cut at intervals larger than the designed length of the piezoelectric element, and insulating material is filled in the cut groove and solidified;

[0044] An electrode is plated on one side of the piezoelectric material, and a backing layer is poured or attached on the electrode-plated side;

[0045] The piezoelectric material is thinned to the designed thickness from the side without electrode plating, and an electrode is plated on the thinned side;

[0046] The conductive matching layer is made:

[0047] The bulk matching layer material is cut along the length direction of the piezoelectric element or cut in the length direction and width direction respectively, and conductive material is filled in the cut groove;

[0048] The matching layer is thinned on both sides to expose the conductive strips and to the designed thickness, or thinned on one side to expose the conductive strips, and the exposed conductive strip side is bonded to the piezoelectric layer, and then the other side of the matching layer is thinned to expose the conductive strips and to the designed thickness;

[0049] Alternatively, the conductive matching layer is made of conductive material;

[0050] Alternatively, both sides of the conductive matching layer are plated with a conductive layer;

[0051] The piezoelectric element is made:

[0052] The piezoelectric material bonded with the conductive matching layer is cut into individual elements, one end of the element in the length direction is piezoelectric material, the other end is filled insulating material, and the signal pole and ground pole are led out on the same side or different sides of the piezoelectric material.

[0053] In some preferred embodiments, when bonding the conductive matching layer, the conductive strips of the conductive matching layer are placed in line with the insulating strips of the piezoelectric material in the width direction, and / or,

[0054] The piezoelectric element has one or more matching layers, and at least the innermost matching layer is conductive.

[0055] According to another aspect of the present application, a piezoelectric element is further provided, which is made by the above method, and has a working frequency greater than or equal to 20 MHz and a working area less than or equal to 1.0 square millimeters.

[0056] According to still another aspect of the present application, there is further provided an ultrasonic transducer having the piezoelectric array element as described above.

[0057] The present application has at least the following advantages:

[0058] 1. The piezoelectric array element for ultrasonic transducer and its manufacturing method provided by the present application, by increasing the non-piezoelectric material area of the piezoelectric layer to lead the signal electrode out of the non-working area of the piezoelectric array element through the conductive matching layer, on one hand, the conductive material of the leading electrode is arranged in the non-piezoelectric material area, deviating from the emitting area of the acoustic wave, which can avoid the impedance difference between the matching layer affecting the boundary condition of the piezoelectric material, improving the imaging resolution and sensitivity of the ultrasonic transducer, and improving the consistency of the performance between products; on the other hand, leading the signal electrode through the conductive matching layer can ensure the flatness of the front surface of the piezoelectric layer, which is beneficial to the pouring and pasting of the conductive matching layer, and can be suitable for more matching layer materials;

[0059] 2. The piezoelectric array element for ultrasonic transducer and its manufacturing method provided by the present application, the piezoelectric material is cut at an interval larger than the designed length of the piezoelectric array element, and the non-piezoelectric material area is formed by filling insulating material in the cutting seam, the width of the piezoelectric array element manufactured is the same as the existing process, and the long side is slightly longer than the existing process, but the effective length of the piezoelectric material is the same as the existing process, so that the influence of the point-painted conductive silver paste on the acoustic performance is eliminated while the effective working area of the ultrasonic transducer is unchanged;

[0060] 3. The piezoelectric array element for ultrasonic transducer and its manufacturing method provided by the present application, after the electrodes are plated on both sides of the piezoelectric layer, the thickness of the piezoelectric material is cut along one side of the piezoelectric material and the formed insulating strip, so that the insulating material is separated from the piezoelectric material, thereby forming an air gap, which avoids the insulating material being driven to vibrate transversely when the piezoelectric material vibrates, and affects the piezoelectric performance;

[0061] 4. The piezoelectric array element for ultrasonic transducer and its manufacturing method provided by the present application, the non-piezoelectric material area of the piezoelectric layer is arranged at one end of the length direction of the piezoelectric array element, which has the characteristics of convenient implementation;

[0062] 5. The piezoelectric array element for ultrasonic transducer and its manufacturing method provided by the present application, in the case that the matching layer material itself is not conductive and both surfaces are not plated with a conductive layer, a conductive strip arrangement scheme on the matching layer is provided, which can be one or more conductive strips arranged along the length direction of the piezoelectric array element, or each one or more conductive strips arranged along the length direction and the diameter direction of the piezoelectric array element and intersected with each other; preferably, a conductive layer is further plated on the upper and lower surfaces of the matching layer; preferably, the conductive strips of the matching layer are placed coincidentally with the insulating strips of the piezoelectric material during bonding;

[0063] 6. The piezoelectric array element for ultrasonic transducer and its manufacturing method, the signal pole and the grounding pole can be led out on the same surface or different surfaces of the piezoelectric material; when a plurality of conductive matching layers are correspondingly arranged, there is an overlapping part between at least one pair of conductive strips of adjacent conductive matching layers, when the signal pole is finally led out from the outer surface of the conductive matching layer, the conductive material exists in the non-piezoelectric material area corresponding to the outermost conductive matching layer; when the signal pole is finally led out from the outer surface of the backing layer, the conductive material exists in the non-piezoelectric material area corresponding to at least the innermost conductive matching layer;

[0064] 7. The piezoelectric array element for ultrasonic transducer and its manufacturing method, the piezoelectric material and all the matching layers are bonded and then segmented to the final size, which is easy to bond the matching layers and control the thickness of the pouring layer;

[0065] 8. The piezoelectric array element for ultrasonic transducer and its manufacturing method, the signal pole is usually led out from the outer surface of the conductive matching layer, and the grounding pole is led out from the conductive backing. The signal pole can also be led out from the conductive backing and the grounding pole can be led out from the outer surface of the conductive matching layer, which does not affect the content protected by the claims of the present application;

[0066] 9. The piezoelectric array element for ultrasonic transducer and its manufacturing method, the high-frequency ultrasonic transducer is manufactured with a single piezoelectric array element, the working frequency of the piezoelectric array element is greater than or equal to 20MHz, and the area of the working region is less than or equal to 1.0 square millimeter. BRIEF DESCRIPTION OF DRAWINGS

[0067] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings and their labels used in the embodiments will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0068] Figure 1 The process flow chart of the manufacturing method of the piezoelectric array element described in the embodiments of the present application;

[0069] Figure 2 One of the cross-sectional views of the piezoelectric array element in the long axis direction described in the first example of the present application;

[0070] Figure 3 One of the cross-sectional views of the piezoelectric array element in the long axis direction described in the first example of the present application;

[0071] Figure 4 The top view of the piezoelectric array element described in the first example of the present application towards the conductive matching layer;

[0072] Figure 5A cross-sectional view of the piezoelectric array element of Example 2 in the long axis direction;

[0073] Figure 6 A plan view of the piezoelectric array element of Example 2 toward the conductive matching layer;

[0074] Figure 7 A cross-sectional view of the piezoelectric array element of Example 3 in the long axis direction;

[0075] Figure 8 A cross-sectional view of the piezoelectric array element of Example 3 in the long axis direction;

[0076] Figure 9 A cross-sectional view of the piezoelectric array element of Example 4 in the long axis direction;

[0077] Figure 10 A cross-sectional view of the piezoelectric array element of Example 4 in the long axis direction.

[0078] The meanings of the symbols in the figures are as follows:

[0079] 10 - conductive matching layer, 11 - conductive strip;

[0080] 20 - piezoelectric layer, 21 - piezoelectric material, 22 / 23 - insulating material, 24 - air gap;

[0081] 30 - backing layer. DETAILED DESCRIPTION

[0082] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the specific embodiments of the present application will be described below with reference to the drawings. Obviously, the drawings in the following description only represent some of the embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without creative labor, and other embodiments can also be obtained.

[0083] In order to make the drawing simple, only the parts related to the invention are shown in each drawing, which does not represent the actual structure of the product. In addition, in order to make the drawing simple and easy to understand, in some drawings, only one of the components with the same structure or function is shown schematically, or only one of them is marked. In this paper, "one" not only means "only one", but also means "more than one".

[0084] It should be further understood that the term "and / or" used in the specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0085] In this document, unless otherwise indicated and limited, the terms "mount", "connect", "connection" should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0086] In addition, in the description of the present application, the terms "first", "second" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0087] In the present application, the relative position relationship referred to by "front" and "back" refers to the front end and the back end of the sound wave transmission direction of the piezoelectric array element; the orientation relationship referred to by "length direction" refers to the catheter length direction of the ultrasonic transducer in the catheter; and the orientation relationship referred to by "width direction" refers to the catheter diameter direction of the ultrasonic transducer in the catheter.

[0088] In one embodiment, an ultrasonic transducer is provided, comprising a single piezoelectric array element, the piezoelectric array element is sequentially provided with a conductive matching layer, a piezoelectric layer and a backing layer from front to back, wherein the piezoelectric layer has a non-piezoelectric material region, and the two surfaces of the piezoelectric layer are provided with electrode layers through electroplating. The piezoelectric array element further comprises an electrode lead-out structure, specifically including a signal pole cable and a ground pole cable, the signal pole cable is led out from the non-piezoelectric material region corresponding to the conductive matching layer, and the ground pole cable is led out from the backing layer.

[0089] In the embodiment, the conductive material leading out the signal pole is arranged in the non-piezoelectric material region, which deviates from the emission area of the sound wave, so as to avoid the influence of the impedance difference of the matching layer on the boundary conditions of the piezoelectric material, improve the imaging resolution and sensitivity of the ultrasonic transducer, and improve the consistency of the performance between products.

[0090] In the above embodiment, the non-piezoelectric material region is a partition structure formed on the piezoelectric layer, specifically, which can be formed by cutting and filling insulating material; in this embodiment, a large piece of piezoelectric material can be cut at an interval greater than the designed length dimension of the piezoelectric array element, so as to maintain the effective working area of the piezoelectric array element and eliminate the influence of point-pasted conductive silver paste on the acoustic performance.

[0091] In some preferred embodiments, the cuts or slits formed by cutting the piezoelectric material are arranged along the width direction of the piezoelectric layer, and more preferably, the cuts or slits are arranged at the ends of the piezoelectric layer along the length direction, which can be one end or both ends. In a specific example, one end of the piezoelectric layer is made of piezoelectric material, and the other end is filled with insulating material. This design facilitates the control of the effective length of the piezoelectric element in the length direction, and further eliminates the impact of point-coated conductive silver paste on acoustic performance while ensuring the effective size of the piezoelectric element remains unchanged.

[0092] Further, an air gap 24 is provided between the piezoelectric material and the insulating material to prevent the piezoelectric material from driving the insulating material to vibrate laterally when the piezoelectric material vibrates, thereby affecting the piezoelectric performance.

[0093] In the above embodiments, the conductive matching layer can be made by plating a conductive layer on both sides of the matching layer, or the matching layer itself can be made of conductive material. When the conductive matching layer is not plated on both sides and is not made of conductive material itself, a conductive strip is provided on the conductive matching layer, and the conductive strip leads out the signal electrode corresponding to the non-piezoelectric material area, which can ensure the flatness of the front surface of the piezoelectric layer, facilitate the pouring and pasting of the conductive matching layer, and be suitable for more matching layer materials.

[0094] In some specific embodiments, the conductive matching layer has one or more conductive strips arranged along the length direction, or one or more conductive strips arranged along the length direction and the diameter direction intersect with each other. When the effective area of the piezoelectric element is provided with one conductive strip, the large piece of matching layer material is cut at a pitch larger than the size of the piezoelectric element. When the effective area of the piezoelectric element is provided with multiple conductive strips in the same direction, the large piece of matching layer material is cut at a pitch smaller than the size of the piezoelectric element.

[0095] Preferably, the conductive strips arranged along the diameter direction on the conductive matching layer coincide with the positions of the insulating strips on the piezoelectric layer.

[0096] In some preferred embodiments, the conductive matching layer is a plurality of layers stacked together, and there is an overlapping part between at least one pair of conductive strips of adjacent conductive matching layers. When the signal electrode is finally led out from the outer surface of the conductive matching layer, the non-piezoelectric material area corresponding to the outermost conductive matching layer has conductive material. When the signal electrode is finally led out from the outer surface of the backing layer on the side of the piezoelectric layer away from the conductive matching layer, the non-piezoelectric material area corresponding to at least the innermost conductive matching layer has conductive material.

[0097] The piezoelectric element provided in the embodiments has a working frequency greater than or equal to 20 MHz, and an effective working area less than or equal to 1.0 square millimeter. The effective working area of the piezoelectric element is the part corresponding to the non-piezoelectric material area on the piezoelectric layer. Specifically, the piezoelectric material can be piezoelectric ceramic, piezoelectric single crystal, piezoelectric composite material, or piezoelectric film.

[0098] In another embodiment, the present invention provides a method for fabricating a piezoelectric array element for an ultrasonic transducer, comprising the following steps:

[0099] Electrodes are plated on both sides of the piezoelectric layer, a signal electrode is formed on one side of the emitting surface, and a ground electrode is formed on the other side away from the emitting surface. The ground electrode is led out from the backing layer of the piezoelectric array element.

[0100] A conductive matching layer is provided to bring the signal electrode out to a location outside the working area of ​​the piezoelectric element.

[0101] The piezoelectric layer has a non-piezoelectric material region, and the signal electrode is led out from the non-piezoelectric material region through the conductive matching layer.

[0102] In this embodiment, the signal electrode is led out from the non-piezoelectric material region through a conductive matching layer. This allows the conductive material of the led-out electrode to be located in the non-piezoelectric material region, away from the sound wave emission region. This avoids the impedance difference with the matching layer affecting the boundary conditions of the piezoelectric material, improves the imaging resolution and sensitivity of the ultrasonic transducer, and enhances the performance consistency between products. Furthermore, leading out the signal electrode through the conductive matching layer ensures the flatness of the front surface of the piezoelectric layer, which is beneficial for the casting and application of the conductive matching layer and can be used with a wider range of matching layer materials.

[0103] In a preferred embodiment, the non-piezoelectric material region on the piezoelectric layer is formed by cutting the piezoelectric material at intervals larger than the designed length of the piezoelectric element, and filling the cuts with insulating material. This design facilitates control of the effective length of the piezoelectric element in the length direction, thereby eliminating the acoustic performance impact caused by the spot application of conductive silver paste while ensuring that the effective size of the piezoelectric element remains unchanged.

[0104] More preferably, after electrodes are plated on both sides of the piezoelectric layer, the thickness of the piezoelectric material is cut along one side of the piezoelectric material and the formed insulating strip, so that the insulating material and the piezoelectric material are separated, thereby forming an air gap 24.

[0105] In another preferred embodiment, the method of setting non-piezoelectric material regions on the piezoelectric layer is as follows: after the piezoelectric material completes the conductive matching layer without cutting grooves, the backing material and the piezoelectric material are cut off at the end of the piezoelectric element along the width direction in the length direction to form the layer. The cutting depth must be greater than or equal to the total thickness of the backing layer and the piezoelectric layer.

[0106] In another preferred embodiment, the method of setting non-piezoelectric material areas on the piezoelectric layer is as follows: the piezoelectric material is cut along the width direction of the piezoelectric array element, and conductive material is filled into the cut. After the conductive matching layer is completed, a groove is cut on one side of the backing layer according to the length dimension of the piezoelectric array element, and insulating material is filled in. The depth of the groove needs to be greater than the sum of the thickness of the backing and the piezoelectric material.

[0107] In the above embodiments, the conductive matching layer can be directly formed by plating conductive layers on both sides, or by using a conductive material matching layer, or by cutting to form conductive strips. Specifically, the conductive strip manufacturing process includes: cutting one or more conductive strips along the length direction of the piezoelectric element, or cutting one or more conductive strips along the length direction and the width direction of the piezoelectric element, respectively, and the conductive strips intersect with each other. Preferably, the conductive strips of the conductive matching layer coincide with the non-piezoelectric material region of the piezoelectric layer.

[0108] In a preferred embodiment, the conductive matching layer is a plurality of layers stacked on each other, and there is a coincident part of at least one pair of conductive strips between adjacent conductive matching layers. When the signal electrode is finally led out from the outer surface of the conductive matching layer, the non-piezoelectric material region corresponding to the outermost conductive matching layer has conductive material. When the signal electrode is finally led out from the outer surface of the backing layer on the side of the piezoelectric layer away from the matching layer, the non-piezoelectric material region corresponding to the innermost conductive matching layer has conductive material.

[0109] In another embodiment, the present application provides a piezoelectric element and an ultrasonic transducer thereof, wherein the working frequency of the piezoelectric element is greater than or equal to 20 MHz, and the area of the working region is less than or equal to 1.0 square millimeters.

[0110] In order to have a clearer understanding of the technical solutions of the present application and the technical effects thereof, the following specific examples are provided:

[0111] Example 1

[0112] Referring to Figure 1 , the manufacturing steps of the piezoelectric element for the ultrasonic transducer are as follows:

[0113] I. Polishing and gold plating of piezoelectric material

[0114] Polish the upper and lower surfaces of the large piece of piezoelectric material to be flat, and the thickness is greater than the designed frequency thickness;

[0115] Cut the piezoelectric material in one or more directions at intervals greater than the designed length of the piezoelectric element, and the cutting depth is less than the thickness of the piezoelectric material;

[0116] Fill the cutting groove with insulating material 22, such as epoxy resin, and after curing, polish the piezoelectric material 21 on both sides to expose the cutting groove on each side;

[0117] Plate an electrode on one side of the piezoelectric material 21, and pour or attach a backing material on the electrode-plated side, and then polish the backing layer 30 to be flat;

[0118] Thin the piezoelectric material 21 to the designed frequency thickness from the un-plated electrode side of the piezoelectric material 21, and plate an electrode on the thinned side.

[0119] II. Manufacturing the conductive matching layer (see Figures 2-4 )

[0120] Cut the big piece of matching layer material along the length direction of the piezoelectric array, when the piezoelectric array has one matching layer and the matching layer has one conductive strip, the cutting interval is greater than or equal to the designed width of the piezoelectric array, and fill the conductive material in the cutting slot.

[0121] Thin the two sides of the matching layer to expose the conductive strip 11 and to the designed thickness, then plate the conductive layer on both sides / or not. Adhere to the electrode surface of the piezoelectric material 21; Or thin one side to expose the conductive strip 11, plate the conductive layer on the exposed conductive strip surface / or not, and then adhere to the electrode surface of the piezoelectric material. Thin the other side of the matching layer until the conductive strip 11 is exposed and to the designed thickness, and plate the conductive layer / or not. When adhering, the conductive strip 11 of the conductive matching layer 10 is preferably placed in coincidence with the insulating strip of the piezoelectric material 21, or it can be placed without coincidence. When placed without coincidence, the transducer needs to have a conductive area in the non-working area.

[0122] Manufacture the piezoelectric array:

[0123] Divide the piezoelectric material 21 adhered with the conductive matching layer 10 into single piezoelectric arrays, one end of each piezoelectric array in the length direction is the piezoelectric material 21, and the other end is the filled insulating material 22. The conductive strip 11 of each transducer matching layer is arranged along the length direction of the transducer. The signal pole and the ground pole are led out on the same surface or different surfaces of the piezoelectric material.

[0124] Example Two

[0125] See Figures 5-6 The manufacturing process is basically the same as that of Example One, the only difference is:

[0126] Cut the matching layer along the length direction and the width direction of the piezoelectric array respectively, and fill the conductive material; among them, the conductive strip 11 filled along the width direction of the piezoelectric array is aligned with the insulating strip of the piezoelectric material when the matching layer is adhered to the piezoelectric material.

[0127] Example Three

[0128] See Figures 7-8 The manufacturing process is similar to that of Example One, the difference is in the following steps:

[0129] After the piezoelectric material is adhered with the conductive matching layer without cutting, cut off the backing material and the piezoelectric material at one end of the piezoelectric array in the length direction along the width direction to expose the innermost conductive strip 11 of the conductive matching layer 10.

[0130] Example Four

[0131] See Figures 9-10, fill in conductive material in the slot, then follow the process of example 1 / example 2 to complete the conductive matching layer, cut a slot in the back of the piezoelectric array according to the length of the piezoelectric array, fill in insulating material 23, the depth of the slot is greater than the thickness of the backing layer 30 and the piezoelectric layer 20. After solidification, follow example 1 to divide the large piece of material into the final size of the piezoelectric array.

[0132] Example Five

[0133] The piezoelectric array is configured with a multi-layer conductive matching layer 10. If the conductive layer is not plated on both sides of each layer of the conductive matching layer 10 and the matching layer itself is not conductive, then there is at least one pair of conductive strips 11 overlapping between each adjacent matching layer. If the two electrodes of the piezoelectric material are respectively led out from the matching layer surface and the backing surface, then the non-working area of the outermost matching layer of the transducer needs to have conductive material. If the two electrodes of the piezoelectric material are both led out from the backing surface, then the first matching layer of the non-working area of the transducer needs to have conductive material. The optimal solution is that the conductive strips 11 of the matching layer and the insulating strips of the piezoelectric material are located at one short side of the transducer, i.e. the non-working area of the transducer.

[0134] Example Six

[0135] In examples 1-5, when the material of a certain matching layer itself is conductive, it is not necessary to use the method of cutting and then making conductive strips to make the matching layer. The material of this layer can be directly thinned to the designed thickness.

[0136] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A method of fabricating a piezoelectric element for an ultrasonic transducer, characterized by, The method comprises the steps of: forming a signal electrode on one side of the piezoelectric layer and a ground electrode on the other side of the piezoelectric layer, and leading the ground electrode out of the backing layer of the piezoelectric element; providing a non-piezoelectric material region on the piezoelectric layer, and leading the signal electrode out of the non-piezoelectric material region to a position outside the working region of the piezoelectric element through the conductive matching layer; the working frequency of the piezoelectric element is greater than or equal to 20 MHz, and the area of the working region is less than or equal to 1.0 square millimeter.

2. The production method according to claim 1, characterized by, The non-piezoelectric material region on the piezoelectric layer is provided in the following manner: cutting the piezoelectric material at intervals greater than the designed length of the piezoelectric element, and filling the cutting gap with insulating material to form the non-piezoelectric material region.

3. The method of manufacturing according to claim 2, wherein, The piezoelectric layer is made in the following steps: after the electrodes are plated on both sides of the piezoelectric layer, cut the piezoelectric material along the side of the piezoelectric material and the formed insulating strip to the thickness of the piezoelectric material, so that the insulating material and the piezoelectric material are separated, thereby forming an air gap.

4. The method of making of claim 1, wherein, The non-piezoelectric material region on the piezoelectric layer is provided in the following manner: after the piezoelectric material is completed without cutting the groove for the conductive matching layer, the backing material and the piezoelectric material are cut off at the end of the length direction of the piezoelectric element along the width direction to form, and the cutting depth needs to be greater than or equal to the total thickness of the backing layer and the piezoelectric layer.

5. The method of making of claim 1, wherein, The non-piezoelectric material region on the piezoelectric layer is provided in the following manner: cut the piezoelectric material along the width direction of the piezoelectric element, fill the cutting gap with conductive material, complete the conductive matching layer, and cut a groove on the side of the backing layer according to the length size of the piezoelectric element after the conductive matching layer is completed, and fill it with insulating material, the depth of the cutting groove needs to be greater than the sum of the thickness of the backing and the piezoelectric material.

6. The method of any of claims 1-5, wherein, The conductive matching layer is made in the following steps: cut one or more conductive strips along the length direction of the piezoelectric element, or cut one or more conductive strips respectively along the length direction and the width direction of the piezoelectric element; at least one of the conductive strips partially or completely overlaps with the non-piezoelectric material of the piezoelectric layer.

7. The manufacturing method according to claim 6, wherein: the conductive matching layer is a plurality of layers superimposed on each other, and at least one pair of conductive strips between adjacent conductive matching layers has an overlapping part; when the signal electrode is finally led out from the outer surface of the conductive matching layer, the non-piezoelectric material region corresponding to the outermost conductive matching layer has conductive material; when the signal electrode is finally led out from the outer surface of the backing layer on the side of the piezoelectric layer away from the matching layer, the non-piezoelectric material region corresponding to at least the innermost conductive matching layer has conductive material.

8. The method of making of claim 1, wherein, The method comprises the following specific steps: making a piezoelectric layer: cut the piezoelectric material at intervals greater than the designed length of the piezoelectric element, fill the cutting gap with insulating material and solidify; plate an electrode on one side of the piezoelectric material, and pour or attach a backing layer on the electrode-plated side; thin the piezoelectric material to the designed thickness from the side of the piezoelectric material not plated with the electrode, and plate an electrode on the thinned side; making a conductive matching layer: cut a large piece of matching layer material along the length direction of the piezoelectric element, or cut it along the length direction and the width direction respectively, and fill the cutting gap with conductive material; The conductive matching layer is thinned on both sides to expose the conductive strips and to the designed thickness, and is bonded to the piezoelectric layer, or is thinned on one side to expose the conductive strips, the side with the exposed conductive strips is bonded to the piezoelectric layer, and the other side of the matching layer is thinned until the conductive strips are exposed and to the designed thickness; Alternatively, the conductive matching layer is made of conductive material; Alternatively, both sides of the conductive matching layer are plated with a conductive layer; The piezoelectric array element is made by: The piezoelectric material bonded with the conductive matching layer is cut into single array elements, one end of the array element in the length direction is piezoelectric material, the other end is filled with insulating material, the signal pole and the ground pole are led out on the same side or different sides of the piezoelectric material; The piezoelectric array element has one or more matching layers, and at least part of the conductive area of the innermost matching layer coincides with the insulating strip of the piezoelectric material.

9. An ultrasonic transducer, characterized by The piezoelectric array element obtained by the manufacturing method of any one of claims 1-8. The piezoelectric array element obtained by the manufacturing method of any one of claims 1-8.

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