Thermal insulation composite piezoelectric ultrasonic transducer structure and its forming process

Abstract

The present invention provides a thermal insulation composite piezoelectric ultrasonic transducer structure and its forming process, which belongs to the field of non-destructive testing. The thermal insulation composite piezoelectric ultrasonic transducer structure is composed of an SMA connector, a metal shielding layer, an epoxy resin encapsulation layer, a backing layer, a cavity, a matching layer, a piezoelectric ceramic chip, an inner thermal insulation and sound absorption layer, and an outer thermal insulation and sound absorption layer. The present invention aims to solve the problem of the influence of above-zero and below-zero ambient temperatures (such as ‑20℃‑40℃, etc.) on the performance of the piezoelectric ultrasonic transducer when the piezoelectric ultrasonic transducer is placed outside the concrete structure and the concrete structure is tested by being attached to the surface of the concrete structure or coupled with the air. The piezoelectric ultrasonic transducer has good signal accuracy and reliability when working at different temperatures, and the sensitivity difference of the transducer caused by temperature changes is reduced.

Description

Technical Field

[0001] The invention provides a structure and a forming process of a heat-insulating composite piezoelectric ultrasonic transducer externally placed in concrete, belonging to the field of non-destructive testing. Background Art

[0002] Ultrasonic measurement has long been widely used for characterizing concrete structures. Piezoelectric ceramic wafers are the functional units in piezoelectric ultrasonic transducers that enable ultrasonic excitation and reception. However, temperature fluctuations are a significant factor affecting the positioning accuracy of piezoelectric ceramics, with their performance significantly varying with temperature. This results in differences in the sensitivity of piezoelectric ultrasonic transducers operating in different temperature environments, adversely affecting the accuracy and reliability of their ultrasonic signals.

[0003] In light of this, a structure and molding process for a thermally insulated composite piezoelectric ultrasonic transducer for external placement in concrete was proposed. This approach aims to address the impact of ambient temperatures (e.g., -20°C to 40°C) on the performance of the piezoelectric ultrasonic transducer when the transducer is attached to the concrete surface or coupled to air for inspection. This approach ensures that the transducer maintains excellent signal accuracy and reliability at varying temperatures, reducing sensitivity variations caused by temperature fluctuations. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a structure and molding process of a thermal insulation composite piezoelectric ultrasonic transducer externally placed on concrete. The transducer has a three-layer structure. The three-layer shielding shell provides very effective protection for the transducer. The thermal insulation and sound absorption layer can not only absorb noise but also keep the transducer at a stable operating temperature, thereby maintaining the sensitivity of the transducer.

[0005] The technical solutions provided in this application are:

[0006] The thermal insulation composite piezoelectric ultrasonic transducer structure has an SMA connector at the top of the transducer and a backing layer at the bottom. The backing layer is a cylindrical structure with a piezoelectric ceramic chip at the bottom and the top connected to the inner thermal insulation and sound absorption layer. The piezoelectric chip is located in the middle of the transducer and is placed horizontally in the cavity in the middle of the innermost shielding layer. A matching layer is provided on the coaxial side of the piezoelectric chip. The structure is provided with several shielding layers, each of which is an annular cylindrical metal shell with corrosion-resistant properties. Different packaging layers are provided at the ends of the shielding layers, and the packaging layers are used to bond and encapsulate the internal and external structures.

[0007] Furthermore, the structure contains three independent shielding layers from the outside to the inside, namely the first shielding layer outer shell, the second shielding layer outer shell and the shielding layer inner shell, wherein the axis of the SMA connector of the first shielding layer outer shell and the second shielding layer outer shell is the axis, and is distributed in a stepped manner, and an arc-shaped notch with a diameter of r is formed at the center height of the outer side of the ring column of the shielding layer inner shell, and the cavity has a depth not exceeding the wall thickness of the shielding layer inner shell.

[0008] Furthermore, the packaging layer includes four parts, namely, a first upper packaging layer arranged at the upper end of the first shielding layer shell, the first upper packaging layer is connected to the SMA connector, the first shielding layer shell, the shielding layer inner shell, the outer thermal insulation and sound absorption layer, and the inner thermal insulation and sound absorption layer; a second upper packaging layer arranged at the upper end of the second shielding layer shell, the second upper packaging layer is used to connect the first shielding layer shell, the second shielding layer shell and the outer thermal insulation and sound absorption layer; an inner packaging layer arranged at the contact position between the two ends of the piezoelectric chip and the shielding layer inner shell, and a lower packaging layer arranged at the contact position between the two ends of the matching layer and the second shielding layer shell; wherein, the inner packaging layer is used to fix the piezoelectric ceramic chip on the matching layer and bond it to the backing layer and the shielding layer inner shell; the lower packaging layer is an annular wedge-shaped platform.

[0009] Furthermore, the matching layer is a cylindrical structure, part of which is embedded in the inner shell of the shielding layer and bonded with an adhesive.

[0010] Furthermore, the structure is further provided with an outer heat-insulating and sound-absorbing layer, and the outer heat-insulating and sound-absorbing layer is connected to the first upper packaging layer, the second upper packaging layer and the lower packaging layer.

[0011] Furthermore, the shielding layers used in the structure are all annular cylindrical metal shells with anti-corrosion properties; the encapsulation layer is an epoxy resin adhesive; the backing layer is a mixture of an adhesive material containing metal powder or silicon powder as a matrix; the matching layer is a material such as acrylic or alumina ceramic used for acoustic impedance matching; and the thermal insulation and sound absorption layer is a porous material.

[0012] This application also provides a forming process for the above-mentioned heat-insulating composite piezoelectric ultrasonic transducer, and the process is specifically divided into the following steps:

[0013] S1, embed the matching layer into the inner shell of the shielding layer, and lead the wires from the piezoelectric ceramic wafer; fix the piezoelectric ceramic wafer on the matching layer with the inner packaging layer, so that the inner packaging layer is at the same height as the upper surface of the piezoelectric ceramic wafer; the axes of the inner shell of the shielding layer, the matching layer, and the piezoelectric ceramic wafer are collinear;

[0014] S2, filling the backing layer material into the shielding layer inner shell, wherein the liquid level of the backing layer material does not exceed the height of the ring column of the shielding layer inner shell; when the backing layer material no longer has fluidity, an inner thermal insulation and sound absorption layer is stacked on top of it;

[0015] S3 embeds the inner shell of the shielding layer into the outer thermal insulation and sound absorbing layer so that their bottom surface heights are consistent. The outer shell of the second shielding layer is inserted into the outer thermal insulation and sound absorbing layer so that the vertical distance between the lower end of the second shielding layer outer shell and the lower end of the matching layer is not less than zero. The wires leading out of the piezoelectric ceramic chip are connected to the SMA connector placed on the inner thermal insulation and sound absorbing layer so that the axes of the SMA connector, each shielding layer, thermal insulation and sound absorbing layer, backing layer, matching layer, and piezoelectric ceramic chip are collinear.

[0016] S4, pouring the first upper packaging layer material into the upper part of the transducer after step S3 to connect and fill it, so that it encapsulates the upper structure of the transducer; after the first upper packaging layer is cured, flip the probe over and pour the lower packaging layer to encapsulate the lower structure of the transducer and form it.

[0017] The beneficial effects of the present invention are as follows: using epoxy resin or other adhesive matrix as the packaging layer and backing layer of the thermal insulation composite piezoelectric ultrasonic transducer can make it have a certain ability to resist stress, and the shielding layer, packaging layer, and backing layer are all corrosion-resistant. The structure and molding process of the above-mentioned composite piezoelectric ultrasonic transducer make it have good waterproof performance. The metal shielding layer and the backing layer containing metal powder or silicon powder make the thermal insulation composite piezoelectric ultrasonic transducer have certain anti-electromagnetic interference characteristics. The backing layer and the porous thermal insulation and sound absorption layer of the thermal insulation composite piezoelectric ultrasonic transducer suppress the noise interference generated by the piezoelectric transducer, and the lower packaging layer of the annular wedge-shaped platform can reflect some redundant signals when receiving ultrasonic signals. The three-layer shielding shell provides very effective protection for the transducer. The thermal insulation and sound absorption layer can not only absorb noise but also keep the transducer at a stable operating temperature. The sandwich combination of the shielding shell and the thermal insulation and sound absorption layer effectively reduces the self-vibration of the transducer during operation, so that the piezoelectric transducer can more accurately distinguish signal characteristics during operation. When using a thermal insulation composite piezoelectric ultrasonic transducer attached to the concrete surface or coupled with air for concrete testing, this transducer construction method can reduce the sensitivity differences of the transducer caused by temperature changes (such as -20℃ to 40℃, etc.), ensuring good signal accuracy and reliability when the piezoelectric ultrasonic transducer operates at different temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0019] Figure 1 This is a structural diagram of an external heat-insulating composite piezoelectric ultrasonic transducer;

[0020] Figure 2 The cross-sectional structural dimension marking diagram of an external heat-insulating composite piezoelectric ultrasonic transducer;

[0021] Figure 3 This is an oblique axonometric cutaway view of an external heat-insulating composite piezoelectric ultrasonic transducer;

[0022] Figure 4 It is a side view of an external heat-insulating composite piezoelectric ultrasonic transducer;

[0023] Figure 5 It is a top view of an external heat-insulating composite piezoelectric ultrasonic transducer;

[0024] Figure 6 This is a bottom view of an external heat-insulating composite piezoelectric ultrasonic transducer;

[0025] Figure 7 This is an exploded diagram of the structure of an external thermal insulation composite piezoelectric ultrasonic transducer;

[0026] Figure 8 This is a flow chart of the molding process of an external heat-insulating composite piezoelectric ultrasonic transducer;

[0027] Figure 9 This is a schematic diagram of the transducer response test system;

[0028] Figure 10 is the sensitivity response curve of the transducer at various temperatures;

[0029] Figure 11 This is the sensitivity response curve in the −20 ℃-40 ℃ environment. Implementation Method

[0030] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with examples. It should be understood that the specific implementation described herein is only used to explain the present invention and is not intended to limit the present invention. Example

[0031] The thermal insulation composite piezoelectric ultrasonic transducer structure has an SMA connector at the top of the transducer and a backing layer at the bottom. The backing layer is a cylindrical structure with a piezoelectric ceramic chip at the bottom and the top connected to the inner thermal insulation and sound absorption layer. The piezoelectric chip is located in the middle of the transducer and is placed horizontally in the cavity in the middle of the innermost shielding layer. A matching layer is provided on the coaxial side of the piezoelectric chip. The structure is provided with several shielding layers, each of which is an annular cylindrical metal shell with corrosion-resistant properties. Different packaging layers are provided at the ends of the shielding layers, and the packaging layers are used to bond and encapsulate the internal and external structures.

[0032] Furthermore, the structure comprises three independent shielding layers from the outside inward: a first shielding outer shell, a second shielding outer shell, and a shielding inner shell. The SMA connectors of the first and second shielding outer shells are centered on each other and arranged in a stepped pattern. An arc-shaped notch with a diameter of r is formed around the center height of the outer ring of the shielding inner shell, forming a cavity. The cavity depth does not exceed the wall thickness of the shielding inner shell. Air is contained within the notch, adding some damping between the sound-absorbing layer and the inner wall, reducing sound transmission between the structure and the outside, and thus minimizing structural self-vibration and noise interference.

[0033] Furthermore, the packaging layer includes four parts, namely, a first upper packaging layer arranged at the upper end of the first shielding layer shell, the first upper packaging layer is connected to the SMA connector, the first shielding layer shell, the shielding layer inner shell, the outer thermal insulation and sound absorption layer, and the inner thermal insulation and sound absorption layer; a second upper packaging layer arranged at the upper end of the second shielding layer shell, the second upper packaging layer is used to connect the first shielding layer shell, the second shielding layer shell and the outer thermal insulation and sound absorption layer; an inner packaging layer arranged at the contact position between the two ends of the piezoelectric chip and the shielding layer inner shell, and a lower packaging layer arranged at the contact position between the two ends of the matching layer and the second shielding layer shell; wherein, the inner packaging layer is used to fix the piezoelectric ceramic chip on the matching layer and bond it to the backing layer and the shielding layer inner shell; the lower packaging layer is an annular wedge-shaped platform.

[0034] Furthermore, the matching layer is a cylindrical structure, part of which is embedded in the inner shell of the shielding layer and bonded with an adhesive.

[0035] Furthermore, the structure is further provided with an outer heat-insulating and sound-absorbing layer, and the outer heat-insulating and sound-absorbing layer is connected to the first upper packaging layer, the second upper packaging layer and the lower packaging layer.

[0036] Furthermore, the shielding layers used in the structure are all annular cylindrical metal shells with anti-corrosion properties; the encapsulation layer is an epoxy resin adhesive; the backing layer is a mixture of an adhesive material containing metal powder or silicon powder as a matrix; the matching layer is a material such as acrylic or alumina ceramic used for acoustic impedance matching; and the thermal insulation and sound absorption layer is a porous material.

[0037] See Figure 1 The external thermal insulation composite piezoelectric ultrasonic transducer is composed of 14 structural layers, including an SMA connector 1, a metal shielding layer, an epoxy resin packaging layer, a backing layer 3, a cavity 6, a matching layer 12, a piezoelectric ceramic chip 13, an inner thermal insulation and sound absorption layer 14, and an outer thermal insulation and sound absorption layer 8.

[0038] See Figures 1 to 2The external heat-insulating composite piezoelectric ultrasonic transducer contains three independent shielding layers from the outside to the inside, all of which are annular cylindrical metal shells with corrosion-resistant properties. The first shielding layer is the first shielding layer shell 4, whose annular wall thickness is 1.5mm, height is 6mm, inner diameter is 17mm, and outer diameter is 20mm. The second shielding layer is the shielding layer inner shell 7, whose annular wall thickness is 2mm, height is 12mm, inner diameter is 10mm, and outer diameter is 14mm. At its height of 6mm, there is an arc-shaped notch with a diameter of 3mm and a depth of 1mm. The third shielding layer is the second shielding layer shell 9, whose annular wall thickness is 2mm, height is 12mm, inner diameter is 22mm, and outer diameter is 26mm.

[0039] See Figures 1 to 2 Each encapsulation layer is made of epoxy resin or other adhesive and is used to bond and encapsulate the internal and external structures. The inner encapsulation layer 11 secures the piezoelectric ceramic wafer 13 to the matching layer 12 and bonds it to the backing layer 3 and the inner shielding shell 7. The first upper encapsulation layer 2 is connected to the SMA connector 1, the first shielding shell 4, the inner shielding shell 7, the outer insulation and sound absorption layer 8, and the inner insulation and sound absorption layer 14. The second upper encapsulation layer 5 connects the first shielding shell 4, the second shielding shell 9, and the outer insulation and sound absorption layer 8. The lower encapsulation layer 10 is an annular wedge-shaped platform with an inner ring diameter of 10 mm, an outer ring diameter of 22 mm, a height of 3 mm, and a slope height difference of 0.5 mm. The average values ​​of the piezoelectric strain constant 33, capacitance, dielectric loss tangent, characteristic frequency ft, and impedance Zr of the piezoelectric ceramic wafer 13 used in this example measured at 25° C. are 376.5 pC·N-1, 1167.2 pF, 1.77%, 4.03 MHz, and 5.45 Ω, respectively.

[0040] See Figure 1 The matching layer 12 is a cylindrical structure made of a material used for acoustic impedance matching, such as acrylic or alumina ceramic. It is partially embedded in the shielding layer inner shell 7 and bonded with an adhesive. The backing layer 3 is a mixture of epoxy resin or other adhesive materials containing metal powder or silicon powder. It is a cylindrical structure fixed to the shielding layer inner shell 7. Its lower portion contains a piezoelectric ceramic chip 13, and its upper portion is connected to the inner thermal insulation and sound absorption layer 14.

[0041] See Figure 1 The outer insulation and sound absorption layer 8 is made of a porous material such as asbestos or foam cotton, and is connected to the three independent shielding layers: the first upper packaging layer 2, the second upper packaging layer 5, and the lower packaging layer 10. The shielding layer inner shell 7 and the outer insulation and sound absorption layer 8 are combined to form a cavity structure.

[0042] The oblique axonometric cross-sectional view of the external heat-insulating composite piezoelectric ultrasonic transducer is as follows: Figure 3 As shown, the side view is Figure 4 As shown, the top view is Figure 5As shown, the bottom view is as follows Figure 6 shown. Figure 7 The structural explosion diagram of 14 structural composites of external thermal insulation composite piezoelectric ultrasonic transducers is shown. Example

[0043] See Figure 8 The present application also provides a forming process for the thermal insulation composite piezoelectric ultrasonic transducer. The process is specifically divided into the following steps:

[0044] (1) The matching layer 12 is embedded in the shielding layer inner shell 7 by 2 mm, and the wire is led out from the piezoelectric ceramic chip 13. The piezoelectric ceramic chip 13 is fixed on the matching layer 12 by the inner packaging layer 11. The inner packaging layer 11 is at the same height as the upper surface of the piezoelectric ceramic chip 13. The axes of the shielding layer inner shell 7, the matching layer 12, and the piezoelectric ceramic chip 13 are collinear. Figure 8 As shown in (a).

[0045] (2) Fill the backing layer material containing a mixture of metal powder or silicon powder, epoxy resin or other adhesive materials into the shielding layer inner shell 7. As an optional technical solution, the liquid level height of the backing layer 3 material is 5 mm. After the backing layer material no longer has fluidity, an inner insulation and sound absorption layer 14 is superimposed on it, such as Figure 8 (b)~8(c) show.

[0046] (3) Insert the shielding layer inner shell 7 into the outer thermal insulation and sound absorption layer 8 so that their bottom surface heights are consistent. Insert the second shielding layer outer shell 9 into the outer thermal insulation and sound absorption layer 8 so that the vertical distance between the lower end of the second shielding layer outer shell 9 and the lower end of the matching layer 12 is 0.5 mm. Connect the wires leading out of the piezoelectric ceramic chip 13 to the SMA connector 1 placed on the inner thermal insulation and sound absorption layer 14 so that the axes of the SMA connector 1, shielding layer, thermal insulation and sound absorption layer, backing layer 3, matching layer 12, and piezoelectric ceramic chip 13 are collinear. Figure 8 (d) shown.

[0047] (4) Fill the first upper packaging layer 2 material Figure 8 (d) The upper structure shown is connected and filled to achieve Figure 8 (e) The packaging effect shown. After the first upper packaging layer 2 is solidified, the probe is flipped over and the lower packaging layer 10 is encapsulated to achieve the desired effect. Figure 8 (f) shows the packaging effect.

[0048] See Figure 9According to the standard: Nondestructive Testing - Secondary Calibration Specification for Acoustic Emission Sensors (GB / T 19801-2005 / ISO 12714: 1999), the transducer sensitivity was calibrated using a face-to-face calibration method. The transducers were placed symmetrically to transmit and receive elastic waves from the surface of a solid medium. The sensor sensitivity was then calibrated using the output signal. The transducer frequency response test method is shown in Figure 9. A function waveform generator (DG 4202) outputs a linear frequency sweep signal with a peak-to-peak voltage of 2 Vp-p and a frequency range of 0 Hz-10 MHz for 360 seconds. This signal is transmitted by an embedded composite piezoelectric ultrasonic transducer (without thermal insulation) and received by an external thermally insulated composite piezoelectric ultrasonic transducer. The transmitting and receiving transducers are placed close together, and the air between the two shielding shells is isolated using ultrasonic coupling agent (TZM-A, temperature range: -60°C to 250°C). After multiple measurements within the entire signal source frequency band (1-10 MHz), the response of the entire transmitting-receiving transducer within this frequency band can be calculated.

[0049] The embedded composite piezoelectric ultrasonic transducer (without thermal insulation effect) outputs, and the external thermal insulation composite piezoelectric ultrasonic transducer receives (the characteristic frequency ft of the piezoelectric ceramic chip 13 measured at 25°C is 4.03MHz). Figure 10 ~ Figure 11 ,As can be seen from the figure, within the frequency bandwidth range of 1 ~ 6 MHz, the ,configured sensitivity offset is small, and the maximum fluctuation range is ± 2 dB. Figure 11 This more intuitively demonstrates the response fluctuations of the transmitter-receiver configuration over a frequency bandwidth of 1 to 6 MHz as temperatures vary. In ambient temperatures ranging from −20°C to 40°C, the sensitivity standard deviation of the configuration using an embedded composite piezoelectric ultrasonic transducer (without insulation) for output and an externally mounted composite piezoelectric ultrasonic transducer for reception is close to zero, demonstrating excellent signal accuracy and reliability. This suggests that when both the output and receiving transducers are insulated, the configuration can achieve even better signal accuracy and reliability when operating at varying temperatures. In summary, the composite piezoelectric ultrasonic transducer mounted externally in concrete maintains excellent signal accuracy and reliability when operating at varying temperatures, mitigating sensitivity variations caused by temperature fluctuations.

Claims

1. A heat-insulating composite piezoelectric ultrasonic transducer structure, characterized in that: The top of the transducer is an SMA connector, and the bottom is a backing layer. The backing layer is a cylindrical structure with a piezoelectric ceramic chip at the bottom and the top connected to the inner thermal insulation and sound absorption layer. The middle of the transducer is a piezoelectric ceramic chip, which is placed horizontally in the middle of the innermost shielding layer. A matching layer is provided on the coaxial side of the piezoelectric ceramic chip. The structure is provided with several shielding layers, each of which is a ring-shaped cylindrical metal shell with corrosion-resistant properties. Different packaging layers are provided at the ends of the shielding layers, and the packaging layers are used to bond and encapsulate the internal and external structures. The structure contains three independent shielding layers from the outside to the inside, namely the first shielding layer outer shell, the second shielding layer outer shell and the shielding layer inner shell. Among them, the first shielding layer outer shell is distributed in a stepped manner with the axis of the SMA connector of the second shielding layer outer shell as the axis, and an arc-shaped notch with a diameter of r is formed at the center height of the outer side of the ring column of the shielding layer inner shell, and the cavity depth does not exceed the wall thickness of the shielding layer inner shell.

2. The heat-insulating composite piezoelectric ultrasonic transducer structure according to claim 1, characterized in that: The packaging layer comprises four parts: a first upper packaging layer provided at the upper end of the first shielding layer shell, the first upper packaging layer being connected to the SMA connector, the first shielding layer shell, the shielding layer inner shell, the outer thermal insulation and sound absorption layer, and the inner thermal insulation and sound absorption layer; a second upper packaging layer provided at the upper end of the second shielding layer shell, the second upper packaging layer being used to connect the first shielding layer shell, the second shielding layer shell, and the outer thermal insulation and sound absorption layer; an inner packaging layer provided at the contact position between the two ends of the piezoelectric ceramic wafer and the shielding layer inner shell, and a lower packaging layer provided at the contact position between the two ends of the matching layer and the second shielding layer shell; wherein the inner packaging layer is used to fix the piezoelectric ceramic wafer on the matching layer and bond it to the backing layer and the shielding layer inner shell; and the lower packaging layer is an annular wedge-shaped platform.

3. The heat-insulating composite piezoelectric ultrasonic transducer structure according to claim 1, characterized in that: The matching layer is a cylindrical structure, part of which is embedded in the inner shell of the shielding layer and bonded with an adhesive.

4. The heat-insulating composite piezoelectric ultrasonic transducer structure according to claim 1, characterized in that: The structure is further provided with an outer heat-insulating and sound-absorbing layer, which is connected to the first upper packaging layer, the second upper packaging layer and the lower packaging layer.

5. The heat-insulating composite piezoelectric ultrasonic transducer structure according to claim 1, characterized in that: The shielding layer used in the structure is an annular cylindrical metal shell with anti-corrosion properties; the encapsulation layer is an epoxy resin adhesive; the backing layer is a mixture with an adhesive material containing metal powder or silicon powder as a matrix; the matching layer is acrylic or alumina ceramic material used for acoustic impedance matching; and the thermal insulation and sound absorption layer is a porous material.

6. The forming process of the heat-insulating composite piezoelectric ultrasonic transducer according to claim 1, characterized in that: The process of the process is specifically divided into the following steps: S1, embed the matching layer into the inner shell of the shielding layer, and lead the wires from the piezoelectric ceramic wafer; fix the piezoelectric ceramic wafer on the matching layer with the inner packaging layer, so that the inner packaging layer is at the same height as the upper surface of the piezoelectric ceramic wafer; the axes of the inner shell of the shielding layer, the matching layer, and the piezoelectric ceramic wafer are collinear; S2, filling the backing layer material into the shielding layer inner shell, wherein the liquid level of the backing layer material does not exceed the height of the ring column of the shielding layer inner shell; when the backing layer material no longer has fluidity, an inner thermal insulation and sound absorption layer is stacked on top of it; S3: Embed the inner shell of the shielding layer within the outer thermal insulation and sound absorption layer, ensuring that their bottom surface heights are consistent. Insert the outer shell of the second shielding layer into the outer thermal insulation and sound absorption layer, ensuring that the vertical distance between the lower end of the second shielding layer and the lower end of the matching layer is not less than zero. Connect the wires leading out of the piezoelectric ceramic chip to the SMA connector placed on the inner thermal insulation and sound absorption layer, ensuring that the axes of the SMA connector, each shielding layer, thermal insulation and sound absorption layer, backing layer, matching layer, and piezoelectric ceramic chip are collinear. S4, pouring the first upper packaging layer material into the upper part of the transducer after step S3 to connect and fill it, so that it encapsulates the upper structure of the transducer; after the first upper packaging layer is cured, flip the probe over and pour the lower packaging layer to encapsulate the lower structure of the transducer and form it.

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