Deep-sea imaging sonar and method of manufacturing the same

Abstract

The application relates to a deep-sea imaging sonar and a manufacturing method thereof, the deep-sea imaging sonar comprising a control circuit and a piezoelectric ceramic sensing array, the piezoelectric ceramic sensing array comprising, from bottom to top, a PCB circuit board, a backing layer, a piezoelectric layer and an acoustic matching layer. The piezoelectric layer is a 1-3 type composite structure composed of an M*M soft piezoelectric ceramic column array and insulating epoxy resin filled in the joint gap between adjacent soft piezoelectric ceramic columns. The array scale is 24*24 to 48*48, and the deep-sea imaging sonar has excellent transceiving integrated performance. The deep-sea imaging sonar is manufactured by using integrated forming and micro-processing technology, the piezoelectric ceramic sensing array element consistency and yield can be ensured, the high-frequency array assembly time and qualified rate are shortened, and the work efficiency is further improved.

Description

Technical Field

[0001] This invention relates to the field of sonar technology, specifically to a deep-sea imaging sonar and its manufacturing method. Background Technology

[0002] Deep-sea imaging sonar, as a core piece of equipment for marine resource exploration, seabed geological surveys, and underwater target identification, has its performance directly determined by its core sensor—the transducer array. To obtain finer imaging resolution, sonar systems are constantly evolving towards higher operating frequencies (hundreds of kHz) and more array elements, aiming to utilize high-frequency sound waves to improve detail resolution and achieve more precise beam control and a wider scanning field of view through large-scale arrays.

[0003] However, achieving large-scale arrays (such as 24×24 and above) in the 300-500kHz high-frequency band faces severe technological challenges. High-frequency requirements necessitate a significant reduction in the size of individual array elements, making them susceptible to breakage due to mechanical stress during fabrication; dense array arrangement exacerbates crosstalk between elements and leads to a surge in interconnect wiring complexity. These issues severely impact the consistency of element performance and the overall array yield, thus placing extremely high demands on high-precision cutting, electrode patterning, and microcircuit interconnect processes.

[0004] To address these challenges, flexible piezoelectric polymers (such as polyvinylidene fluoride and its copolymers) have been considered ideal materials for receiver arrays due to their acoustic impedance being close to that of water (approximately 1.5 M ayl), facilitating broadband acoustic matching. However, the inherently low piezoelectric strain constant (d) of such materials... 33 Typically below -25 pC / N, this makes it difficult to meet the driving performance required for transmitting sound waves, and it can usually only be used as a pure receiving element, requiring an additional transmitting sound source. This separate transmitting and receiving structure not only increases the system complexity, but also limits the flexibility of ultrasonic beam formation and control. Summary of the Invention

[0005] Therefore, it is necessary to provide a deep-sea imaging sonar and its manufacturing method to address the above problems, so as to achieve a deep-sea imaging sonar with high frequency (300-500kHz), high sensitivity, large scale (≥24×24 array elements), high consistency, and integrated transmission-reception function.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A deep-sea imaging sonar includes a control circuit and a piezoelectric ceramic sensing array, wherein the piezoelectric ceramic sensing array comprises, from bottom to top:

[0008] A PCB circuit board, which is electrically connected to the control circuit.

[0009] The backing layer located on the surface of the PCB circuit board is a type 1-3 composite structure consisting of an M×M array of conductive epoxy resin pillars and tungsten powder-filled polyurethane adhesive filling the spaces between adjacent conductive epoxy resin pillars.

[0010] The piezoelectric layer located on the surface of the backing layer is a type 1-3 composite structure composed of an M×M array of soft piezoelectric ceramic pillars and insulating epoxy resin filling the slits between adjacent soft piezoelectric ceramic pillars. The soft piezoelectric ceramic pillars correspond one-to-one with the conductive epoxy resin pillars. The upper surface of each soft piezoelectric ceramic pillar is provided with a negative electrode, and adjacent negative electrodes are electrically connected to each other and grounded. The lower surface of each soft piezoelectric ceramic pillar is provided with a positive electrode, and adjacent positive electrodes are insulated from each other. Each positive electrode is electrically connected to the control circuit through the conductive epoxy resin pillar.

[0011] An acoustic matching layer, which covers the surface of the piezoelectric layer;

[0012] Where 24≤M≤48, M∈Z.

[0013] In one embodiment, the width of the slit between adjacent soft piezoelectric ceramic pillars is 0.28 mm to 0.32 mm.

[0014] In one embodiment, the center-to-center distance between adjacent soft piezoelectric ceramic pillars is d = 1 / 2λ. 水 , where λ 水 The wavelength of the sound wave at the operating frequency of the deep-sea imaging sonar in the water medium.

[0015] In one embodiment, the thickness of the soft piezoelectric ceramic column is t = 1 / 2λ. PZT , where λ PZT The wavelength is the wavelength in the corresponding thickness vibration mode of the soft piezoelectric ceramic column.

[0016] In one embodiment, the deep-sea imaging sonar further includes an adhesive layer located on the surface of the tungsten powder-filled polyurethane adhesive structure of the backing layer, the adhesive layer being used for bonding and fixing between the PCB circuit board and the backing layer, and between the backing layer and the piezoelectric layer.

[0017] In one embodiment, the tungsten powder-filled polyurethane adhesive is formed by mixing and curing tungsten powder and polyurethane adhesive in a weight ratio of 1:1.

[0018] In one embodiment, the control circuit includes:

[0019] A signal excitation system, which is electrically connected to the positive electrode, is used to send a detection signal to the piezoelectric ceramic sensing array;

[0020] A data acquisition system, which is electrically connected to the positive electrode, is used to acquire the echo signal received by the piezoelectric ceramic sensing array;

[0021] A multiplexer switch is located between the signal excitation system, the data acquisition system, and the positive electrode. It is used to switch the positive electrode between the signal excitation system and the data acquisition system to realize the signal transmission and signal acquisition of the piezoelectric ceramic sensing array.

[0022] Another embodiment discloses a method for fabricating a deep-sea imaging sonar, wherein the method for fabricating the piezoelectric ceramic sensor array of the deep-sea imaging sonar includes:

[0023] Piezoelectric layer fabrication:

[0024] A square soft piezoelectric ceramic blank is selected, cut along the X-axis, filled with insulating epoxy resin and cured, and then cut along the Y-axis, filled with insulating epoxy resin and cured.

[0025] The back side of the soft piezoelectric ceramic blank is ground and polished to form an M×M soft piezoelectric ceramic column array and an insulating epoxy resin filling the cut between adjacent soft piezoelectric ceramic columns, forming a type 1-3 composite structure.

[0026] A negative electrode is formed on the upper surface of the soft piezoelectric ceramic pillar, and adjacent negative electrodes are electrically connected to each other.

[0027] A positive electrode is formed on the lower surface of the soft piezoelectric ceramic pillar, and adjacent positive electrodes are insulated from each other;

[0028] Preparation of the tungsten powder-filled polyurethane adhesive structure for the backing layer:

[0029] Using flexible resin as the material and employing photopolymerization 3D printing technology, a columnar array casting mold with the same arrangement as the soft piezoelectric ceramic column array is prepared.

[0030] After mixing tungsten powder with polyurethane adhesive and removing bubbles, the mixture is poured into the mold. After curing and demolding, a tungsten powder-filled polyurethane adhesive structure is formed as a backing layer. The tungsten powder-filled polyurethane adhesive structure has an M×M through-hole array.

[0031] Assembly:

[0032] The PCB circuit board and the tungsten powder-filled polyurethane adhesive structure of the backing layer are aligned and fixed, and conductive epoxy resin is filled into the through-hole array to form a backing layer on the PCB circuit board. The piezoelectric layer is aligned and fixed with the backing layer.

[0033] Conductivity and Packaging:

[0034] The negative electrode is grounded, and the acoustic matching layer is encapsulated on the piezoelectric layer.

[0035] In one embodiment, the PCB circuit board and the backing layer, as well as the backing layer and the piezoelectric layer, are bonded and fixed together by an adhesive layer.

[0036] In one embodiment, the cutting depth of the soft piezoelectric ceramic preform is greater than 1 / 2λ. PZT .

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] I. Because the piezoelectric layer is a type 1-3 composite structure composed of an M×M array of soft piezoelectric ceramic pillars and insulating epoxy resin filling the slits between adjacent soft piezoelectric ceramic pillars, the deep-sea imaging sonar provided by this invention combines the high-voltage strain constant (d) of soft piezoelectric ceramics. 33 This ensures high electro-acoustic energy conversion (emission) and a high voltage constant (g). 33 This ensures high acoustic-to-electrical conversion sensitivity (receiver), enabling the sonar to have excellent transceiver performance.

[0039] Second, since the effective number of array elements of the piezoelectric ceramic sensing array is between 24×24 and 48×48, and it can both transmit and receive signals for superposition, it is equivalent to a huge receiving aperture, thereby enabling the detection of weak echo signals and increasing the detection distance.

[0040] Third, the backing layer is a type 1-3 composite structure composed of M×M conductive epoxy resin pillars and tungsten powder-filled polyurethane adhesive filling the spaces between adjacent conductive epoxy resin pillars. Through structural and material optimization, the typical acoustic impedance of the backing layer can reach 7~10 MNayl, and the typical acoustic attenuation coefficient can reach 40~45 dB / (cm·MHz). The high acoustic impedance and high acoustic attenuation coefficient of the backing layer can effectively absorb rearward radiated vibration energy while suppressing various transverse vibration modes, suppressing stray modes, and achieving electrical conductivity through the conductive epoxy resin pillars.

[0041] IV. The method for manufacturing the deep-sea imaging sonar adopts an integrated molding and micro-machining process, which can ensure the consistency and yield of piezoelectric ceramic sensor array elements, shorten the assembly time and pass rate of high-frequency array, and further improve work efficiency.

[0042] Furthermore, the deep-sea imaging sonar provided by this invention eliminates the need for traditional mechanical rotation devices. It can expand the effective acoustic field of view by controlling the transmission delay of different array elements to change the direction of the acoustic beam. It can also precisely control the phase of the transmitted signals from each array element, allowing all sound waves to be synchronously superimposed at a specific point to form a sharp acoustic focus, with adjustable focus depth, thus providing high lateral / longitudinal resolution. Moreover, the beam width and shape can be controlled through software programming, for example, generating a wide beam for rapid searching and a narrow beam for fine discrimination. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a deep-sea imaging sonar structure provided in an embodiment of the present invention;

[0044] Figure 2 An array arrangement diagram of the piezoelectric layer of a deep-sea imaging sonar provided in an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of a positive electrode structure for a deep-sea imaging sonar provided in an embodiment of the present invention;

[0046] Figure 4 This is a schematic diagram of a negative electrode structure for a deep-sea imaging sonar provided in an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of another deep-sea imaging sonar structure provided in an embodiment of the present invention;

[0048] Figure 6 This is a schematic diagram of an adhesive layer structure for a deep-sea imaging sonar provided in an embodiment of the present invention;

[0049] Figure 7 This is a schematic diagram of a deep-sea imaging sonar transmitting and receiving signals, provided as an embodiment of the present invention.

[0050] Among them, 11, PCB circuit board; 12, backing layer; 121, conductive epoxy resin pillar; 122, tungsten powder filled polyurethane adhesive; 13, piezoelectric layer; 131, soft piezoelectric ceramic pillar; 1311, negative electrode; 1312, positive electrode; 1313, interconnecting metal wire; 132, insulating epoxy resin; 14, acoustic matching layer; 15, adhesive layer; 151, hole; 20, control circuit. Detailed Implementation

[0051] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0053] One embodiment of the present invention discloses a deep-sea imaging sonar, including a control circuit and a piezoelectric ceramic sensor array. Wherein, as... Figure 1 As shown, the piezoelectric ceramic sensing array comprises, from bottom to top:

[0054] PCB circuit board 11, which is electrically connected to the control circuit 20;

[0055] The backing layer 12 located on the surface of the PCB circuit board 11 is a type 1-3 composite structure consisting of an array of M×M conductive epoxy resin pillars 121 and tungsten powder filled polyurethane adhesive 122 filling the spaces between adjacent conductive epoxy resin pillars 121.

[0056] The piezoelectric layer 13 located on the surface of the backing layer 12 is a type 1-3 composite structure composed of an M×M array of soft piezoelectric ceramic pillars 131 and insulating epoxy resin 132 filled in the slits between adjacent soft piezoelectric ceramic pillars 131. The soft piezoelectric ceramic pillars 131 correspond one-to-one with the conductive epoxy resin pillars 121. The upper surface of the soft piezoelectric ceramic pillars 131 is provided with negative electrodes 1311, and adjacent negative electrodes 1311 are electrically connected to each other and grounded. The lower surface of the soft piezoelectric ceramic pillars 131 is provided with positive electrodes 1312, and adjacent positive electrodes 1312 are insulated from each other. Each positive electrode 1312 is electrically connected to the control circuit 20 through the conductive epoxy resin pillars 121.

[0057] An acoustic matching layer 14 covers the surface of the piezoelectric layer 13;

[0058] Where 24≤M≤48, M∈Z.

[0059] As can be seen, the deep-sea imaging sonar disclosed in the embodiments of the present invention has a piezoelectric ceramic sensing array of 24×24~48×48.

[0060] The soft piezoelectric ceramic pillar 131 is made of soft piezoelectric ceramics such as PZT-5A, PZT-5H, or PZT-5J. PZT (lead zirconate titanate) is one of the most widely used piezoelectric ceramic materials, possessing excellent piezoelectricity, dielectric properties, and electromechanical coupling performance. PZT-5A, PZT-5H, and PZT-5J are soft piezoelectric ceramics with high piezoelectric voltage constants (g). 33 ) and electromechanical coupling coefficient (k 33 It can efficiently convert received water acoustic pressure into electrical signals, even if the signal is extremely weak.

[0061] In the piezoelectric layer 13, insulating epoxy resin 132 surrounds the soft piezoelectric ceramic pillars 131 and completely fills the slits between adjacent soft piezoelectric ceramic pillars 131, thus forming a type 1-3 composite structure. In this structure, the soft piezoelectric ceramic pillars 131 are responsible for the efficient conversion between electrical energy and mechanical energy (sound waves). Although the insulating epoxy resin 132 itself does not possess piezoelectricity, it serves as a structural support and acoustic matching / isolation medium, optimizing the overall acoustic behavior. The piezoelectric layer disclosed in this embodiment can significantly improve acoustic-electric conversion efficiency, broadband performance, acoustic impedance matching, and structural reliability, representing a key innovative design for realizing a high-sensitivity, high-resolution, and multifunctional deep-sea exploration and imaging system.

[0062] Furthermore, the array of elements of the piezoelectric layer is arranged as follows: Figure 2 As shown.

[0063] The width k of the slit between adjacent soft piezoelectric ceramic pillars 131 is 0.28 mm to 0.32 mm. For example, the width k of the slit between adjacent soft piezoelectric ceramic pillars 131 can be 0.28 mm, 0.29 mm, 0.30 mm, 0.31 mm, or 0.32 mm. Slits within this range can ensure good isolation between adjacent array elements and avoid crosstalk. The center-to-center distance d between adjacent soft piezoelectric ceramic pillars 131 is 1 / 2λ. 水 , where λ 水 The wavelength of the sound wave at the operating frequency of the deep-sea imaging sonar in the water medium is given. This allows for the suppression of grating lobes in the piezoelectric layer across the entire operating scanning angle range. In this embodiment, the width of the array element (a single soft piezoelectric ceramic pillar 131) is a = dk. The thickness t of the soft piezoelectric ceramic pillar 131 is the thickness of the piezoelectric layer, and t = 1 / 2λ. PZT , where λ PZT This refers to the wavelength of the soft piezoelectric ceramic column 131 in the corresponding thickness vibration mode. At this point, it can resonate at the sonar operating frequency to achieve maximum electromechanical conversion efficiency.

[0064] In one embodiment, a positive electrode is disposed on the lower surface of the soft piezoelectric ceramic pillar, and adjacent positive electrodes are insulated from each other. That is, as... Figure 3 As shown, the positive electrode 1312 is disposed corresponding to the soft piezoelectric ceramic pillar 131. In order to effectively isolate each positive electrode 1312, the side length L of the positive electrode 1312 in this embodiment is... 正 Satisfies: 0.6×a≤L 正 ≤0.8×a.

[0065] The upper surface of the soft piezoelectric ceramic pillar is provided with a negative electrode, and adjacent negative electrodes are electrically connected to each other and grounded. Specifically, the negative electrode can be a full-surface electrode or a patterned electrode. Figure 4 As shown, when the negative electrode 1311 is a patterned electrode, its side length L 负 Satisfies: 0.6×a≤L 负 ≤0.8×a, the line width w of the interconnecting metal line 1313 between adjacent negative electrodes 1311 is 1mm~2mm.

[0066] In another embodiment, the backing layer is a type 1-3 composite structure consisting of an M×M array of conductive epoxy resin pillars and tungsten powder-filled polyurethane adhesive filling the spaces between adjacent conductive epoxy resin pillars. The tungsten powder-filled polyurethane adhesive is formed by mixing and curing tungsten powder and polyurethane adhesive at a weight ratio of 1:1. The introduction of high-density tungsten powder achieves both "mass loading" and "acoustic impedance enhancement" within the polyurethane matrix. Simultaneously, the flexibility and processability of polyurethane enable engineering applications with high attenuation characteristics. In this embodiment, the tungsten powder-filled polyurethane adhesive has an acoustic impedance of 7 MNayl and an acoustic attenuation coefficient of 45 dB / (cm·MHz). The conductive epoxy resin pillars are made of high-silver-content conductive epoxy resin, with a typical cured acoustic impedance of 15~20 MNayl and a typical acoustic attenuation coefficient of 12~15 dB / (cm·MHz). As can be seen, the backing layer has high acoustic impedance and high acoustic attenuation capability, which can effectively absorb and dampen the back acoustic waves from the piezoelectric layer, prevent them from reflecting multiple times inside the structure to form interference signals, and significantly improve the pulse brevity and time resolution of the piezoelectric layer, making it particularly suitable for deep-sea exploration scenarios that require high resolution and short pulse emission.

[0067] In another embodiment, such as Figure 5As shown, the deep-sea imaging sonar also includes an adhesive layer 15 located on the surface of the tungsten powder-filled polyurethane adhesive 122 structure of the backing layer 12. The adhesive layer 15 is used for bonding and fixing between the PCB circuit board 11 and the backing layer 12, and between the backing layer 12 and the piezoelectric layer 13. Through the bonding and fixing of the adhesive layer 15, the components of the piezoelectric ceramic sensor array can be manufactured through positioning, bonding, and pressing processes, greatly improving the manufacturing efficiency of the piezoelectric ceramic sensor array. In actual process conditions, such as... Figure 6 As shown, the adhesive layer 15 can be an insulating polymer double-sided adhesive with a porous array, its thickness ≤10μm, and the arrangement of its porous array is consistent with that of the soft piezoelectric ceramic column array. The diameter d of a single hole 151 is... 粘接 (0.6~0.8)×L 正 .

[0068] In another embodiment, a ring of virtual array elements is further arranged around the flexible piezoelectric ceramic pillar array. These virtual array elements have no corresponding pads on the PCB circuit board, therefore they cannot transmit / receive ultrasonic guided waves and are not truly functional array elements. However, during the process of using adhesive layers to bond and fix the piezoelectric layer, the bonding and electrical connectivity of the outer ring are often inferior to those of the inner ring array elements because the flexible piezoelectric ceramic pillar array is not perfectly flat. Therefore, setting the outer ring of virtual array elements ensures that the electrical conductivity and mechanical bonding of all functional array elements are relatively good.

[0069] In one embodiment, the control circuit includes:

[0070] A signal excitation system, which is electrically connected to the positive electrode, is used to send a detection signal to the piezoelectric ceramic sensing array;

[0071] A data acquisition system, which is electrically connected to the positive electrode, is used to acquire the echo signal received by the piezoelectric ceramic sensing array;

[0072] A multiplexer switch is located between the signal excitation system, the data acquisition system, and the positive electrode. It is used to switch the positive electrode between the signal excitation system and the data acquisition system to realize the signal transmission and signal acquisition of the piezoelectric ceramic sensing array.

[0073] The signal excitation system mainly consists of a signal generator and a power amplifier. Each positive electrode corresponds to one array element. During operation, a multiplexer connects all array elements to the signal excitation system. The signal excitation system generates a high-voltage electrical pulse, causing all array elements to synchronously emit sound waves, forming a powerful composite beam directed towards the target. After transmission, the multiplexer quickly switches the connection from the signal excitation system to the data acquisition system, where only one or more pre-designated array elements receive the echo signal reflected from the target. This achieves integrated transceiver performance.

[0074] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0075] I. Because the piezoelectric layer is a type 1-3 composite structure composed of an M×M array of soft piezoelectric ceramic pillars and insulating epoxy resin filling the slits between adjacent soft piezoelectric ceramic pillars, the deep-sea imaging sonar provided by this invention combines the high-voltage strain constant (d) of soft piezoelectric ceramics. 33 This ensures high electro-acoustic energy conversion (emission) and a high voltage constant (g). 33 This ensures high acoustic-to-electrical conversion sensitivity (receiver), enabling the sonar to have excellent transceiver performance.

[0076] Second, since the effective number of array elements of the piezoelectric ceramic sensing array is between 24×24 and 48×48, and it can both transmit and receive signals for superposition, it is equivalent to a huge receiving aperture, thereby enabling the detection of weak echo signals and increasing the detection distance.

[0077] Third, the backing layer is a type 1-3 composite structure composed of an M×M array of conductive epoxy resin pillars and tungsten powder-filled polyurethane adhesive filling the spaces between adjacent conductive epoxy resin pillars. Through structural and material optimization, the typical acoustic impedance of the backing layer can reach 7~10 MNayl, and the typical acoustic attenuation coefficient can reach 40~45 dB / (cm·MHz). The high acoustic impedance and high acoustic attenuation coefficient of the backing layer can effectively absorb rearward radiated vibration energy while suppressing various transverse vibration modes, suppressing stray modes, and achieving electrical conductivity through the conductive epoxy resin pillars.

[0078] Furthermore, the deep-sea imaging sonar provided in this invention does not require traditional mechanical rotation devices. It can expand the effective acoustic field of view by controlling the transmission delay of different array elements to change the direction of the acoustic beam. It can also precisely control the phase of the transmitted signals of each array element, allowing all sound waves to be synchronously superimposed at a specific point to form a sharp acoustic focus, with adjustable focus depth, thereby providing high lateral / longitudinal resolution. Additionally, the beam width and shape can be controlled through software programming, for example, generating a wide beam for rapid searching and a narrow beam for fine discrimination.

[0079] Another embodiment discloses a method for fabricating a deep-sea imaging sonar, wherein the method for fabricating the piezoelectric ceramic sensor array of the deep-sea imaging sonar includes:

[0080] Piezoelectric layer fabrication:

[0081] A square soft piezoelectric ceramic blank is selected, cut along the X-axis, and the cut is filled with insulating epoxy resin and cured. The blank is then cut along the Y-axis, and the cut is filled with insulating epoxy resin and cured.

[0082] The back side of the soft piezoelectric ceramic blank is ground and polished to form an M×M soft piezoelectric ceramic column array and an insulating epoxy resin filling the cut between adjacent soft piezoelectric ceramic columns, forming a type 1-3 composite structure.

[0083] A negative electrode is formed on the upper surface of the soft piezoelectric ceramic pillar, and adjacent negative electrodes are electrically connected to each other. Specifically, it can be fabricated using the following process:

[0084] 1. Full-surface coverage of the negative electrode:

[0085] 1. Magnetron sputtering method: Cr thin film and Au thin film are sequentially deposited onto the surface of a soft piezoelectric ceramic pillar using magnetron sputtering technology, wherein the thickness of the Cr thin film is 10~20nm and the thickness of the Au thin film is 100~200nm.

[0086] 2. Screen printing method: A screen printing plate is made according to the planar dimensions of the soft piezoelectric ceramic column array. The negative electrode is printed on the upper surface of the soft piezoelectric ceramic column by screen printing technology. Then, the silver paste is cured at 40~60℃ to form an Ag thin film negative electrode with a thickness of 5~10μm.

[0087] II. Patterned negative electrode:

[0088] The side length of the negative electrode of each element is L 负 For 0.60×a≤L 负 ≤0.80×a; adjacent array element negative electrodes are interconnected by interconnecting metal lines with a linewidth w of 1~2mm, and are mutually conductive.

[0089] 1. Screen printing method: A screen printing plate is made according to the negative electrode pattern, and the negative electrode is printed on the surface of the soft piezoelectric ceramic pillar by screen printing technology; then, the silver paste is cured at 40~60℃ to form an Ag thin film negative electrode with a thickness of 5~10μm.

[0090] 2. Aerosol Printing Method: Set the printing path according to the negative electrode pattern, use ultrasonic atomization to atomize the silver electrode material ink, set the sheath airflow to 60~100 sccm, the atomizing airflow to 60~100 sccm, the printing platform moving speed to 2~4 mm / s, the platform temperature to 60~80℃, and print an Ag thin film negative electrode with a thickness of 1~2 μm.

[0091] A positive electrode is formed on the lower surface of the soft piezoelectric ceramic pillar, and adjacent positive electrodes are insulated from each other. Specifically, it can be fabricated in the following manner:

[0092] I. Magnetron Sputtering Method: A pyroelectric film with the same planar dimensions as the soft piezoelectric ceramic pillar array is taken. A patterned mask for the positive electrode is prepared using quasi-femtosecond laser cutting technology according to the size of the positive electrode. The patterned mask for the positive electrode is attached to the lower surface of the soft piezoelectric ceramic pillar array, ensuring that the center of any cutout in the patterned mask for the positive electrode overlaps with the center of the corresponding array element. Cr and Au films are sequentially deposited onto the lower surface of the soft piezoelectric ceramic pillars using magnetron sputtering technology, where the thickness of the Cr film is 10~20 nm and the thickness of the Au film is 100~200 nm. The soft piezoelectric ceramic pillar array and the patterned mask for the positive electrode are heated to 100~120℃, and the patterned mask for the positive electrode is thermally peeled off.

[0093] II. Screen Printing Method: A screen printing plate is made according to the positive electrode pattern, and the positive electrode is printed on the surface of the soft piezoelectric ceramic pillar by screen printing technology; then, the silver paste is cured at 40~60℃ to form an Ag thin film positive electrode with a thickness of 5~10μm.

[0094] III. Aerosol Printing Method: Set the printing path according to the positive electrode pattern, use ultrasonic atomization to atomize the silver electrode material ink, set the sheath airflow to 60~100sccm, the atomizing airflow to 60~100sccm, the printing platform moving speed to 2~4mm / s, the platform temperature to 60~80℃, and print an Ag thin film positive electrode with a thickness of 1~2μm.

[0095] Preparation of the tungsten powder-filled polyurethane adhesive structure for the backing layer:

[0096] Using flexible resin as the material and employing photopolymerization 3D printing, a backing layer casting mold with a columnar array arranged in the same manner as the soft piezoelectric ceramic column array is prepared. Based on the photopolymerization 3D printing method, a backing layer casting mold can be formed with the element spacing (the center-to-center distance between adjacent soft piezoelectric ceramic columns) *d* as the spacing, the element width *a* as the side length, and the column height 25 mm, resulting in the same number and arrangement of columns as the soft piezoelectric ceramic array. The specific preparation method includes: using flexible resin for SLA printing, thorough cleaning and curing, and then spraying a semi-permanent release agent.

[0097] Tungsten powder and polyurethane adhesive are mixed, defoamed, and then poured into the backing layer injection mold. After curing and demolding, a tungsten powder-filled polyurethane adhesive structure is formed in the backing layer. Specifically, tungsten powder and polyurethane adhesive can be thoroughly mixed at a weight ratio of 1:1, and after thorough defoaming, poured into the backing layer injection mold; subsequently, it is left to stand under vacuum conditions at 60°C for ≥24 hours to fully cure and form the backing layer. The tungsten powder-filled polyurethane adhesive structure has an M×M through-hole array.

[0098] Assembly:

[0099] The PCB circuit board and the tungsten powder-filled polyurethane adhesive structure of the backing layer are aligned and fixed, and conductive epoxy resin is filled into the through-hole array to form a backing layer on the PCB circuit board. The piezoelectric layer is then aligned and fixed with the backing layer.

[0100] Conductivity and Packaging:

[0101] The negative electrode is grounded, and the acoustic matching layer is encapsulated on the piezoelectric layer.

[0102] The deep-sea imaging sonar manufacturing method disclosed in this invention uses integrated molding and micromachining technology to manufacture the deep-sea imaging sonar, which can ensure the consistency and yield of piezoelectric ceramic sensor array elements, shorten the high-frequency array assembly time and pass rate, and further improve work efficiency.

[0103] In another embodiment, the PCB circuit board and the backing layer, as well as the backing layer and the piezoelectric layer, are bonded and fixed together by adhesive layers. This bonding and fixing allows the components of the piezoelectric ceramic sensor array to be manufactured through positioning, bonding, and pressing processes, greatly improving the manufacturing efficiency of the piezoelectric ceramic sensor array.

[0104] In another embodiment, the cutting depth of the soft piezoelectric ceramic preform is greater than 1 / 2λ. PZT This increases the tolerance for errors during processing and prevents situations where the cutting depth and grinding thickness are insufficient.

[0105] The following will illustrate the deep-sea imaging sonar and its manufacturing method disclosed in this invention through a specific embodiment.

[0106] This embodiment discloses a method for manufacturing a deep-sea imaging sonar, including:

[0107] Piezoelectric layer fabrication:

[0108] Green body selection: Select a square PZT-5H soft ceramic green body with a thickness of (t + 1mm) = 5.0mm.

[0109] Cutting-filling: Using a precision cutter, cut along the X-axis at a spacing of d = 1.5mm, a kerf width of k = 0.3mm, and a cutting depth of 4.5mm (1 / 2λ). PZT Equal to 4.0mm, this cutting depth is greater than 1 / 2λ PZT Cut along the X-axis to obtain a slit. Fill the slit with thoroughly stirred and degassed insulating epoxy resin, and cure it in a vacuum oven at 60°C. After curing, repeat the above cutting (to obtain a Y-axis slit) and filling (Y-axis epoxy resin) steps along the Y-axis.

[0110] Using precision grinding and polishing processes, excess insulating epoxy resin on the surface and excess soft ceramic layer (soft ceramic beyond thickness t) at the bottom are removed, ultimately obtaining a type 1-3 composite structure consisting of a soft piezoelectric ceramic column array of 1.2mm × 1.2mm × 4.0mm and insulating epoxy resin filling the slits between adjacent soft piezoelectric ceramic columns. In this structure, the slit width is 0.3mm, the total thickness is 4.0mm, and the array element is a 26×26 array (including the outer ring virtual array element).

[0111] A negative electrode is formed on the upper surface of the flexible piezoelectric ceramic pillar, and adjacent negative electrodes are electrically connected to each other. Specifically, the negative electrode is prepared using screen printing. A corresponding screen printing plate is first made, and silver paste is printed on the upper surface of the flexible piezoelectric ceramic pillar, followed by curing at 50°C to form an Ag thin film negative electrode with a thickness of approximately 8 μm. The side length L of the negative electrode is... 负 The diameter is 0.70 × a = 0.84 mm; adjacent negative electrodes are connected by interconnecting metal lines with a line width w = 1.5 mm to form a common ground network.

[0112] A positive electrode is formed on the lower surface of the soft piezoelectric ceramic pillar, and adjacent positive electrodes are insulated from each other. Specifically, a pyroelectric film with the same planar dimensions as the soft piezoelectric ceramic array is used, and a patterned mask for the positive electrode is prepared using quasi-femtosecond laser cutting technology according to the dimensions of the positive electrode. The patterned mask for the positive electrode is attached to the lower surface of the soft piezoelectric ceramic array, ensuring that the center of any cutout in the patterned mask for the positive electrode overlaps with the center of the corresponding array element. A Cr film and an Au film are sequentially deposited on the lower surface of the piezoelectric ceramic using magnetron sputtering technology, wherein the thickness of the Cr film is 10 nm and the thickness of the Au film is 200 nm. The soft piezoelectric ceramic array and the patterned mask for the positive electrode are heated to 100°C, and the patterned mask for the positive electrode is pyroelectrically peeled off. The patterned dimensions of the positive electrode are: positive electrode side length L. 正 The diameter is 0.75 × a = 0.9 mm. Furthermore, all positive electrode elements are independent and have no electrical connection.

[0113] Preparation of the tungsten powder-filled polyurethane adhesive structure for the backing layer:

[0114] Using stereolithography (SLA) 3D printing, a backing layer injection mold with 24×24 columnar cavities, each with an adjacent gap of 0.30 mm and a single column size of 1.2 mm × 1.2 mm × 25 mm, was printed using flexible resin. This backing layer injection mold was designed to match the arrangement of the soft piezoelectric ceramic column array.

[0115] Tungsten powder and polyurethane adhesive are mixed in a 1:1 weight ratio, thoroughly stirred, and vacuum degassed before being poured into a mold.

[0116] Curing: Curing at 60°C under vacuum for 24 hours.

[0117] Demolding: The cured backing layer block (tungsten powder filled polyurethane adhesive structure) was removed from the backing layer injection mold. Its acoustic impedance was measured to be 7 MRayl, and its acoustic attenuation coefficient was 45 dB / (cm·MHz).

[0118] Assembly:

[0119] A backing / piezoelectric layer positioning mold, with the outer frame length of the PCB circuit board and the inner frame length of the piezoelectric layer (the same as the backing layer), is placed above the PCB circuit board. Using this positioning fixture, the PCB circuit board and the tungsten powder-filled polyurethane adhesive structure of the backing layer are aligned and fixed. Conductive epoxy resin (e.g., EPO-TEK EE129-4) is filled into the through-hole array of the tungsten powder-filled polyurethane adhesive structure to form a backing layer on the PCB circuit board. The piezoelectric layer is then aligned and fixed to the backing layer. In this embodiment, the conductive epoxy resin serves both acoustic coupling and electrical conduction functions.

[0120] The PCB circuit board and the backing layer, as well as the backing layer and the piezoelectric layer, are bonded and fixed together by adhesive layers. The adhesive layers are made of high-dielectric-constant insulating polymer double-sided adhesive with a thickness of 8 μm, and are cut using a quasi-femtosecond laser with a spacing of d=1.5 mm and a diameter of 0.60 × L. 正 =0.54mm 24×24 hole array. During assembly, first peel off the release film of the adhesive layer, accurately align and place the backing layer on the PCB board, then accurately align and place the piezoelectric layer (positive electrode side down) on the backing layer, place a pressing weight on the negative electrode surface of the piezoelectric layer to apply uniform pressure, and let it stand for 24 hours to allow the conductive epoxy resin to fully cure.

[0121] Conductivity and Packaging:

[0122] The common ground network of the patterned negative electrode is connected to the ground electrode on the PCB board using fine wires and conductive silver paste. The integrated array is placed in a dedicated housing with a 1 / 4 λ front end. 水A positioning slot with a thickness of 0.375 mm is formed. The matching layer molding mold is assembled, and the mixed matching layer potting compound is poured in using a back-side potting method. It is then cured at 60°C for 24 hours to form the acoustic matching layer.

[0123] The key parameters of the deep-sea imaging sonar prepared in this embodiment are as follows:

[0124] Center operating frequency (f0): 500kHz;

[0125] Speed ​​of sound in water (C) 水 ): 1500m / s;

[0126] PZT (PZT-5H) speed of sound (C PZT ): 4000m / s;

[0127] Wavelength in water (λ) 水 ): λ 水 =C 水 / f0=1500 / 500,000=3.0mm;

[0128] wavelength (λ) in PZT (PZT-5H) PZT ): λ PZT =C PZT / f0=4000 / 500,000=8.0mm;

[0129] Center-to-center distance between adjacent soft piezoelectric ceramic pillars (d): d = λ 水 / 2=1.5mm (used to suppress grid lobes);

[0130] Knife width (k): k = 0.3 mm (determined based on process capability);

[0131] Element width (a): a = dk = 1.5 - 0.3 = 1.2 mm;

[0132] Thickness (t) of the soft piezoelectric ceramic column: t = λ PZT / 2=4.0mm (achieving thickness mode resonance).

[0133] During the operation of the deep-sea imaging sonar, a multiplexer first connects all positive electrodes to the signal excitation system, which then generates a high-voltage electrical pulse with a center frequency of 500 kHz. At this time, all array elements synchronously emit sound waves, forming a powerful composite beam directed towards the target. After transmission, the multiplexer quickly switches the connection from the signal excitation system to the data acquisition system, allowing only one or more pre-designated array elements to receive the echo signals reflected from the target. The transmitted and received signals are as follows: Figure 7 As shown, the amplitude V of the array element signal ppWith a voltage ≥10V, clear waveform, and high signal-to-noise ratio, this deep-sea imaging sonar demonstrates that it possesses both high transmit / receive sensitivity and can be used for medium-range, high-resolution deep-sea imaging.

[0134] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The terms "first" and "second" used in this document are for distinction only and are not intended to limit the content of this invention.

[0135] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A deep-sea imaging sonar, comprising a control circuit and a piezoelectric ceramic sensing array, characterized in that, The piezoelectric ceramic sensing array, from bottom to top, comprises: A PCB circuit board, which is electrically connected to the control circuit. The backing layer located on the surface of the PCB circuit board is a type 1-3 composite structure consisting of an M×M array of conductive epoxy resin pillars and tungsten powder-filled polyurethane adhesive filling the spaces between adjacent conductive epoxy resin pillars. The typical acoustic impedance of the backing layer is 7~10 MNayl, and the typical acoustic attenuation coefficient is 40~45 dB / (cm·MHz). The piezoelectric layer located on the surface of the backing layer is a type 1-3 composite structure composed of an M×M array of soft piezoelectric ceramic pillars and insulating epoxy resin filling the slits between adjacent soft piezoelectric ceramic pillars. The soft piezoelectric ceramic pillars correspond one-to-one with the conductive epoxy resin pillars. The upper surface of each soft piezoelectric ceramic pillar is provided with a negative electrode, and adjacent negative electrodes are electrically connected to each other and grounded. The lower surface of each soft piezoelectric ceramic pillar is provided with a positive electrode, and adjacent positive electrodes are insulated from each other. Each positive electrode is electrically connected to the control circuit through the conductive epoxy resin pillar. An acoustic matching layer, which covers the surface of the piezoelectric layer; Where 24≤M≤48, M∈Z.

2. The deep-sea imaging sonar according to claim 1, characterized in that, The width of the slit between adjacent soft piezoelectric ceramic pillars is 0.28mm~0.32mm.

3. The deep-sea imaging sonar according to claim 2, characterized in that, The center-to-center distance between adjacent soft piezoelectric ceramic pillars is d = 1 / 2λ 水 , where λ 水 The wavelength of the sound wave at the operating frequency of the deep-sea imaging sonar in the water medium.

4. The deep-sea imaging sonar according to claim 1, characterized in that, The thickness of the soft piezoelectric ceramic column is t = 1 / 2λ PZT , where λ PZT The wavelength is the wavelength in the corresponding thickness vibration mode of the soft piezoelectric ceramic column.

5. The deep-sea imaging sonar according to claim 1, characterized in that, It also includes an adhesive layer located on the surface of the tungsten powder-filled polyurethane adhesive structure of the backing layer, the adhesive layer being used for bonding and fixing between the PCB circuit board and the backing layer, and between the backing layer and the piezoelectric layer.

6. The deep-sea imaging sonar according to claim 1, characterized in that, The tungsten powder-filled polyurethane adhesive is formed by mixing tungsten powder and polyurethane adhesive in a weight ratio of 1:1 and then curing them.

7. The deep-sea imaging sonar according to claim 1, characterized in that, The control circuit includes: A signal excitation system, which is electrically connected to the positive electrode, is used to send a detection signal to the piezoelectric ceramic sensing array; A data acquisition system, which is electrically connected to the positive electrode, is used to acquire the echo signal received by the piezoelectric ceramic sensing array; A multiplexer switch is located between the signal excitation system, the data acquisition system, and the positive electrode. It is used to switch the positive electrode between the signal excitation system and the data acquisition system to realize the signal transmission and signal acquisition of the piezoelectric ceramic sensing array.

8. A method for manufacturing a deep-sea imaging sonar, characterized in that, The method for fabricating the piezoelectric ceramic sensor array of the deep-sea imaging sonar includes: Piezoelectric layer fabrication: A square soft piezoelectric ceramic blank is selected, cut along the X-axis, filled with insulating epoxy resin and cured, and then cut along the Y-axis, filled with insulating epoxy resin and cured. The back side of the soft piezoelectric ceramic blank is ground and polished to form an M×M soft piezoelectric ceramic column array and an insulating epoxy resin filling the cut between adjacent soft piezoelectric ceramic columns, forming a type 1-3 composite structure. A negative electrode is formed on the upper surface of the soft piezoelectric ceramic pillar, and adjacent negative electrodes are electrically connected to each other. A positive electrode is formed on the lower surface of the soft piezoelectric ceramic pillar, and adjacent positive electrodes are insulated from each other; Preparation of the tungsten powder-filled polyurethane adhesive structure for the backing layer: Using flexible resin as the material and employing photopolymerization 3D printing technology, a columnar array casting mold with the same arrangement as the soft piezoelectric ceramic column array is prepared. After mixing tungsten powder with polyurethane adhesive and removing bubbles, the mixture is poured into the mold. After curing and demolding, a tungsten powder-filled polyurethane adhesive structure is formed as a backing layer. The tungsten powder-filled polyurethane adhesive structure has an M×M through-hole array. Assembly: The PCB circuit board and the tungsten powder-filled polyurethane adhesive structure of the backing layer are aligned and fixed, and conductive epoxy resin is filled into the through-hole array to form a backing layer on the PCB circuit board. The piezoelectric layer is aligned and fixed with the backing layer. Conductivity and Packaging: The negative electrode is grounded, and the acoustic matching layer is encapsulated on the piezoelectric layer.

9. The method for manufacturing a deep-sea imaging sonar according to claim 8, characterized in that, The PCB circuit board and the backing layer, as well as the backing layer and the piezoelectric layer, are bonded and fixed together by adhesive layers.

10. The method for manufacturing a deep-sea imaging sonar according to claim 8, characterized in that, The cutting depth of the soft piezoelectric ceramic preform is greater than 1 / 2λ. PZT .

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