Signal channel leading-out structure of medical ultrasonic transducer

Abstract

The utility model relates to the technical field of ultrasonic transducers, and particularly discloses a medical ultrasonic transducer signal path leading-out structure which comprises a transducer lamination layer, the transducer lamination layer comprises a piezoelectric material, the bottom end of the piezoelectric material is fixedly provided with a conductive backing, one side of the piezoelectric material is fixedly provided with a side edge conductive material, and the other side of the piezoelectric material is fixedly provided with a side edge conductive material. A flexible circuit board is fixedly arranged at the bottom end of the conductive backing, and a conductive matching layer is fixedly arranged at the top end of the piezoelectric material. An electrode does not need to be arranged on the surface or the side face of the piezoelectric material, a signal electrode is led out through the conductive backing, a grounding electrode is led out through the side edge conductive material and the conductive matching layer, the ultrathin piezoelectric element is prevented from being damaged, reliability is improved, the flexible circuit board integrates a signal and a grounding circuit, the structure is compact, and acoustic performance is not affected. The cutting process ensures that array elements are isolated and electrical communication is kept.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of ultrasonic transducer, concretely to a medical ultrasonic transducer signal path leading structure. BACKGROUND

[0002] The high-frequency micro phased array transducer in the intracardiac echocardiography (ICE) catheter has very high reliability and acoustic performance requirements for the signal leading structure. With the increase of imaging frequency, the thickness of piezoelectric material is often thinned to below 0.2 mm, or even close to 0.1 mm, to meet the quarter wavelength vibration mode. At this scale, how to stably lead out the signal pole and the ground pole in the limited space becomes a key challenge for the design of the transducer.

[0003] The current conventional method is to lead out the positive and negative poles of the ICE transducer array element to the ICE catheter handle part through a flexible printed circuit (FPC), and then connect to the ultrasonic system through a coaxial cable. The connection method of the transducer array element and the FPC will affect the structure and acoustic performance of the transducer to varying degrees. Some manufacturers directly bond the lower surface of the piezoelectric material to the FPC to lead out the positive pole (signal pole) of the piezoelectric material, and then bond a copper foil or conductive film on the upper surface of the piezoelectric material to lead out the negative pole (ground pole) of the piezoelectric material. This method has less impact on the structure size of the transducer, but it will seriously affect the acoustic performance of the transducer, resulting in a decrease in performance indicators such as sensitivity, frequency, and bandwidth, and thus reducing the quality of the ultrasonic image. Therefore, we propose a medical ultrasonic transducer signal path leading structure. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a medical ultrasonic transducer signal path leading structure to solve the problem of affecting the acoustic performance of the transducer, resulting in a decrease in performance indicators such as sensitivity, frequency, and bandwidth, and thus reducing the quality of the ultrasonic image in the actual operation process.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical scheme: a medical ultrasonic transducer signal path leading structure, comprising a transducer stack, the transducer stack comprising a piezoelectric material, the bottom end of the piezoelectric material being fixedly provided with a conductive backing, one side of the piezoelectric material being fixedly provided with a side conductive material, the bottom end of the conductive backing being fixedly provided with a flexible circuit board, and the top end of the piezoelectric material being fixedly provided with a conductive matching layer.

[0006] The thickness of the piezoelectric material needs to be adapted to the quarter wavelength vibration mode.

[0007] The piezoelectric material is equally spaced into several array elements of the same size.

[0008] The transducer stack is formed by bonding, and the piezoelectric material, the conductive backing, and the side conductive material are aligned.

[0009] The thickness of the side conductive material is the same as that of the piezoelectric material.

[0010] The thickness of the side conductive material is the thickness of the piezoelectric material plus the thickness of the conductive backing.

[0011] The transducer stack is formed by bonding, and the piezoelectric material, the conductive backing, and the side conductive material are aligned.

[0012] Finally, the conductive matching layer realizes acoustic impedance matching while bearing the conductive function, which is one material with two functions, simplifies the assembly steps, reduces the number of interfaces, and reduces the risk of defects such as cavities and delamination caused by multi-layer bonding. In summary, the utility model solves the contradiction between reliability and acoustic performance in the signal extraction of high-frequency miniature ICE transducer array elements without significantly increasing the axial size of the transducer, and has outstanding practicability, manufacturability and clinical application value. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The side conductive material and the piezoelectric material have the same thickness.

[0014] Figure 2 The side conductive material is the thickness of the piezoelectric material plus the thickness of the conductive backing.

[0015] Figure 3 The transducer stack is formed by bonding, and the piezoelectric material, the conductive backing, and the side conductive material are aligned.

[0016] Figure 4 The transducer array element is cut.

[0017] Figure 5 The transducer stack is formed by bonding, and the piezoelectric material, the conductive backing, and the side conductive material are aligned.

[0018] In the figure: 1, transducer stack; 101, piezoelectric material; 102, conductive backing; 103, side conductive material; 2, flexible circuit board; 3, conductive matching layer. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the utility model.

[0020] Please refer toFigures 1 to 5 The utility model provides a technical scheme: in this embodiment, signal path lead -out structure includes transducer laminated 1, flexible circuit board 2 and conductive matching layer 3, transducer laminated 1 is by piezoelectric material 101, side edge conductive material 103 and conductive backing 102 of setting gradually from top to bottom in proper order, wherein, piezoelectric material 101 can be piezoelectric ceramic or piezoelectric single crystal, or piezoelectric ceramic composite material, piezoelectric single crystal composite material, its upper and lower surfaces form signal pole and ground pole respectively, since the ICE transducer operating frequency in this embodiment is 9MHz, and adopts tungsten carbide as heavy backing material to promote bandwidth and damping performance, therefore piezoelectric material 101 thickness is designed according to quarter wavelength mode.

[0021] Side edge conductive material 103 can be same as piezoelectric material 101 thickness (such as Figure 1 Indicated), side edge conductive material 103 can also be piezoelectric material 101 plus the thickness of conductive backing 102 (such as Figure 2 Indicated), subsequent process is explained with the structure that side edge conductive material 103 is same as piezoelectric material 101 thickness.

[0022] Conductive backing 102 can be that epoxy resin adds metal powder particle after surface plating conductive material, can also use high impedance backing such as tungsten carbide, satisfy acoustic backing function again, have good conductivity, for reliably leading out signal pole of piezoelectric material 101 bottom surface, piezoelectric material 101 two short sides outside, respectively stick side edge conductive material 103, flexible circuit board 2 is located below conductive backing 102, its base material is 25mu thick polyimide PI film, surface etching has copper conductive circuit, the circuit on FPC is arranged according to ICE array element spacing, each pair of array element corresponds a group of parallelly arranged signal pole circuit and ground pole circuit, realizes resistance balance and space optimization, FPC realizes electrical connection with the bottom of conductive backing 102 and the bottom end of side edge conductive material 103 through anisotropic conductive adhesive hot-pressing mode, ensure signal low-loss transmission.

[0023] After completing the above-mentioned laminated assembly, the whole is cured under the assistance of a tool fixture, ensuring the alignment accuracy of each layer. Subsequently, an ultraviolet laser cutting device is used to cut at equal intervals along a direction perpendicular to the array element arrangement, with the cutting depth controlled as follows: completely cutting off the piezoelectric material 101 and the conductive backing 102, and cutting into the polyimide base material of the FPC, but not damaging the copper conductive circuit layer on the surface of the FPC, thereby forming independent transducer array element units while retaining the electrical connectivity of each array element with the FPC. Finally, a conductive matching layer 3 is attached to the top of the entire transducer laminated, and during the attachment process, the conductive matching layer 3 covers the top surface of the piezoelectric material 101 and the side edge conductive material 103 on both sides, thereby conducting the ground pole on the top surface of the piezoelectric material 101 to the ground circuit of the FPC through the side edge conductive material 103, and realizing the reliable lead-out of the ground pole.

[0024] In summary, the signal electrode is led out by the conductive backing 102, and the ground electrode is led out by the side conductive material 103 + conductive matching layer 3. Without directly pasting a copper foil or conductive film on the surface of the piezoelectric material 101, and without plating an electrode on the side of the piezoelectric material, the negative impact of the traditional scheme on the acoustic performance of the transducer such as sensitivity and bandwidth is effectively avoided, while the long-term reliability and manufacturing yield of the lead of the high-frequency ultra-thin ICE transducer array element are improved. In other optional embodiments, the piezoelectric material 101 can also use a piezoelectric single crystal or a piezoelectric composite material; the conductive backing 102 can be replaced with a silver-containing epoxy conductive adhesive; the side conductive material 103 can use graphite sheet, gold foil or conductive polymer or a substance with a metal layer plated on the surface; the FPC conductive circuit can also use gold foil to improve corrosion resistance; the conductive matching layer 3 can also use a matching layer with a sputtered metal layer on the surface, etc.

[0025] In use, first, a set of high-precision tooling fixtures are prepared, which are provided with positioning grooves for positioning the piezoelectric material 101, and blocks are arranged on both sides to ensure the alignment of the components. Then, the piezoelectric material 101 is subjected to surface cleaning treatment to remove contaminants and dry to improve the subsequent bonding reliability. Next, the conductive backing 102 is placed at the bottom of the tool positioning groove, and a layer of epoxy adhesive is coated on its upper surface. Then, the piezoelectric material 101 is carefully placed on the conductive backing 102, with its edges aligned. The side conductive materials 103 are attached on the outside of the two short sides of the piezoelectric material 101, with the bottom ends in contact with the upper surface of the conductive backing 102 and the top ends slightly higher than the top surface of the piezoelectric material 101. To prevent displacement, a small amount of epoxy adhesive is injected into the gap between the side conductive material 103 and the piezoelectric material 101 for preliminary fixation.

[0026] After the assembly of the laminated layers is completed, the entire work is placed in a heating environment for stepwise temperature rising and curing, so that the layers are firmly bonded. After curing, cooling and demolding are performed, and the alignment of the components is checked. Then, the flexible circuit board 2 is attached. Anisotropic conductive adhesive is coated on the corresponding pad area of the flexible circuit board 2, and then the flexible circuit board 2 is attached upside down on the bottom surface of the conductive backing 102, so that the signal circuit is aligned with the conductive backing 102, and the ground circuit is aligned with the bottom end of the side conductive material 103. Electrical connection is achieved through the hot-press bonding process.

[0027] Subsequently, the entire transducer laminated layer with the attached flexible circuit board 2 is fixed on a cutting device, and is cut at equal intervals along a direction perpendicular to the array element arrangement direction. The cutting depth is controlled to completely penetrate the piezoelectric material 101 and the conductive backing 102, and moderately cut into the base material layer of the flexible circuit board 2, but not to cut off the conductive circuit layer on the surface thereof, so as to form independent array elements that are isolated from each other but electrically connected. After cutting is completed, the debris is removed and the cutting area is cleaned.

[0028] Finally, a conductive matching layer 3 is uniformly bonded on the top of the entire transducer stack 1, which covers the top surface of the piezoelectric material 101 and the upper part of the side edge conductive material 103 on both sides, and after being heated and solidified, a continuous conductive path is formed to connect the ground electrode on the top surface of the piezoelectric material 101 to the ground circuit of the flexible circuit board 2 through the side edge conductive material 103, thereby completing the lead-out of the ground electrode. At this point, the medical ultrasonic transducer signal path lead-out structure of the utility model completes the entire installation process, and the entire process does not need to prepare electrodes on the side surface of the piezoelectric material 101, nor does it need to additionally paste a conductive film on the top surface, effectively avoiding damage to the piezoelectric element, while ensuring the reliable lead-out of the signal electrode and the ground electrode.

[0029] In use, the signal electrode is directly led out to the flexible circuit board 2 through the conductive backing 102, while the ground electrode is led out to the flexible circuit board 2 through the side edge conductive material 103 provided on the short side of the piezoelectric material 101 and the conductive matching layer 3, which realizes the conduction between the top surface electrode of the piezoelectric material 101 and the side edge conductive material 103. This design enables the signal electrode and the ground electrode to be synchronously and independently led out from the bottom of the transducer stack 1, without the need for additional copper foil, conductive film or metal mesh as a ground layer on the top surface of the piezoelectric material 101, thereby avoiding the problems of acoustic impedance mismatch, increased energy loss and vibration mode interference caused by additional materials in the traditional scheme, effectively ensuring the sensitivity, center frequency stability and bandwidth performance of the transducer.

[0030] Secondly, this structure avoids the need for metallization treatment on the side surface of the piezoelectric material 101. For high-frequency transducers used in intracardiac ultrasound, if tungsten carbide or other high-density backing is used to adapt to the quarter-wave vibration mode, the thickness can even be thinned. In this dimension, it is extremely difficult to perform continuous and reliable electrode plating on the side surface of the piezoelectric material 101, and it is easy to cause ground failure due to micro-cracks, plating peeling or edge open circuit. The utility model places the side edge conductive material 103 outside the side surface of the piezoelectric material 101 and realizes electrical connection through the conductive matching layer 3, thereby fundamentally avoiding mechanical or chemical processing of the ultra-thin piezoelectric material 101 body, greatly improving the long-term reliability and manufacturing yield of the ground path.

[0031] In addition, the signal pole lines and the ground pole lines on the flexible circuit board 2 are arranged in parallel and have equal width, which not only simplifies the wiring structure, but also realizes resistance balance and electromagnetic coupling symmetry of the two, which is beneficial to suppress common-mode noise and improve signal-to-noise ratio, and at the same time, since the ground function has been integrated into the FPC itself line, it is no longer dependent on the external independent ground layer, so that the overall structure is more compact, which is conducive to realizing high-density array element layout in the ICE catheter head end, and further, after the whole transducer stack 1 is electrically connected with the flexible circuit board 2, the array element cutting is performed, and the cutting depth is accurately controlled to cut through the piezoelectric material 101 and the conductive backing 102 and moderately cut into the base material layer of the flexible circuit board 2 but not cut off the conductive circuit layer, which not only ensures the acoustic isolation of each array element, but also maintains the integrity of the electrical path.

[0032] It should be noted that, in this document, the terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device.

[0033] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A signal path lead-out structure for a medical ultrasound transducer, characterized in that: The transducer stack includes a piezoelectric material, a conductive backing is fixedly disposed at the bottom end of the piezoelectric material, a side conductive material is fixedly disposed on one side of the piezoelectric material, a flexible circuit board is fixedly disposed at the bottom end of the conductive backing, and a conductive matching layer is fixedly disposed at the top end of the piezoelectric material.

2. The signal path lead-out structure of the medical ultrasound transducer according to claim 1, characterized in that: The thickness of the piezoelectric material needs to be adapted to a quarter-wavelength vibration mode.

3. The signal path lead-out structure of the medical ultrasound transducer according to claim 1, characterized in that: The piezoelectric material is divided into several array elements of the same size at equal intervals.

4. The signal path lead-out structure of the medical ultrasound transducer according to claim 2, characterized in that: The transducer stack is formed by bonding, and the piezoelectric material, conductive backing, and side conductive material are uniformly aligned.

5. The signal path lead-out structure of the medical ultrasound transducer according to claim 1, characterized in that: The side conductive material and the piezoelectric material have the same thickness.

6. The signal path lead-out structure of the medical ultrasound transducer according to claim 1, characterized in that: The thickness of the side conductive material is the thickness of the piezoelectric material plus the conductive backing.

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