1. An image sonar receiving array based on a PMUT is characterized by comprising a pressure-bearing shell, a PMUT module, a PCB adapter plate and an electronic bin; the PMUT modules are uniformly distributed on the PCB adapter plate to form an array, and are connected with the PCB adapter plate through pin pads of the PMUT modules, the PCB adapter plate is connected with the electronic bin through a signal transmission interface, and the pressure-bearing shell covers the PMUT modules and is bonded with the PCB adapter plate; the PMUT module comprises a tube shell and a PMUT chip packaged in the tube shell, wherein the PMUT chip comprises uniformly distributed PMUT array elements, the packaged PMUT module forms a cavity on the surface of the PMUT chip, and the PMUT array elements are exposed; and a coupling agent is filled in a cavity between the PMUT module and the pressure-bearing shell.

2. The PMUT-based image sonar receiving array according to claim 1, wherein the PMUT modules form an m × n array, the PMUT chip includes PMUT array elements forming an i × j array, wherein m, n, i, j are positive integers; the image sonar receiving array is a two-dimensional area array, wherein m & i and n & j are both greater than 1; or, the image sonar receiving array is a one-dimensional linear array, wherein one and only one of m · i and n · j are equal to 1.

3. The PMUT-based image sonar receiving array according to claim 1, wherein the PMUT module further comprises an IC circuit on the PMUT chip; the IC circuit is an amplifying and filtering circuit or module of the PMUT signal.

4. The PMUT-based image sonar receiving array according to claim 1, wherein the PMUT module further comprises an IC chip; the IC chip is an amplifying and filtering circuit or module of the PMUT signal.

5. The PMUT-based image sonar receiving array of claim 1, wherein in the PMUT module, the package of the package takes the form of a DFN, QFN or LGA package; the tube shell is made of metal or ceramic materials.

6. The PMUT-based image sonar receiving array according to claim 1, wherein in the PMUT chip, the PMUT array elements include one PMUT element or a plurality of PMUT elements connected in parallel, the PMUT elements are connected with each other by leads to upper electrodes of all PMUT elements, and all PMUT elements share a lower electrode; and the upper electrode and the lower electrode of the PMUT array element are led out to a bonding pad of the PMUT chip through a lead of the PMUT chip.

7. The image sonar receiving array based on the PMUT according to any one of claims 1, 3 or 4, wherein in the PMUT module, after the PMUT chip is bonded and cured with the case, the PMUT chip pad is connected with the lead pad on the case by a bonding wire in a wire bonding manner, and the bonding wire is sealed and protected by the potting adhesive; or when the package structure comprises the IC chip, firstly bonding the IC chip with the tube shell, then bonding the PMUT chip with the IC chip, and respectively connecting the IC chip bonding pad with the pin bonding pad on the tube shell and the PMUT chip bonding pad with the IC chip bonding pad by using bonding wires, wherein the bonding wires are sealed and protected by the pouring sealant.

8. The PMUT-based image sonar receiving array of claim 1, wherein the electronics bins comprise amplification, filtering, acquisition and storage circuitry modules or chips.

9. The PMUT-based image sonar receiving array according to claim 1, wherein the back of the pressure-bearing shell is provided with a cavity, the length and width of the cavity are larger than those of the PMUT module array, and the height of the cavity is smaller than that of the PMUT module.

10. The method for manufacturing a PMUT image sonar receiving array according to any one of claims 1 to 9, comprising the steps of:

1) PMUT chip fabrication

The PMUT chip comprises uniformly distributed PMUT array elements, the PMUT array elements comprise one or more PMUT micro elements connected in parallel, and the PMUT micro elements comprise substrate silicon, top layer silicon, a lower electrode, an upper electrode and a piezoelectric layer; depositing a lower electrode, a piezoelectric layer and an upper electrode on an SOI material, patterning the lower electrode, the piezoelectric layer and the upper electrode respectively, leading out the upper electrode and the lower electrode to a bonding pad of a PMUT chip respectively through a lead of the PMUT chip, and etching substrate silicon to form a cavity structure;

or, further, fabricating IC circuitry on the PMUT chip;

2) PMUT module package

Bonding and curing the PMUT chip and the tube shell, connecting a bonding pad of the PMUT chip and a pin bonding pad on the tube shell through a bonding lead in a lead bonding mode, and sealing and protecting the bonding lead by pouring sealant; after packaging, the PMUT module forms a cavity on the surface of the PMUT chip, and the PMUT array element is exposed;

or when the IC chip is packaged in an integrated mode, firstly, the IC chip is bonded and cured with the tube shell, then, the PMUT chip is bonded and cured with the IC chip, the bonding lead is respectively used for connecting the IC chip bonding pad with the pin bonding pad on the tube shell, and the PMUT chip bonding pad with the IC chip bonding pad, and the bonding lead is sealed and protected by pouring sealant; after packaging, the PMUT module forms a cavity on the surface of the PMUT chip, and the PMUT array element is exposed;

3) connection of PMUT module, PCB adapter plate and electronic cabin

Arranging the PMUT modules on a PCB adapter plate to form an array, and connecting the array through pin pads on the back of a tube shell of the PMUT modules and corresponding pads on the front of the PCB adapter plate; connecting a signal transmission interface between a PCB adapter plate of the integrated PMUT module array and the electronic cabin;

4) pressure-bearing shell encapsulation

Firstly, a couplant is added into a cavity of each PMUT module in the PMUT module array, pouring sealant is coated on an outer frame area of the PCB adapter plate, and then a pressure-bearing shell covers the PMUT modules and is bonded.

Background

The image sonar is a detection imaging device capable of visually acquiring an image of an underwater target area. An image sonar generally consists of a transmitting transducer array, a receiving transducer array and a signal acquisition processing and control system.

The performance of the receiving transducer array as an image sonar electroacoustic conversion element directly influences the imaging quality. The image sonar receiving array is usually composed of hundreds to thousands of receiving array elements, and the parameters of the array elements, such as receiving sensitivity, bandwidth and consistency, will ultimately determine the performance of the image sonar receiving array.

The conventional receiving transducer array is generally formed by mechanically grooving bulk piezoelectric ceramics to form receiving array elements, and then leading positive and negative electrodes of each array element. The image sonar receiving array has higher requirements on the sensitivity, the bandwidth and especially the consistency of array elements, so that the traditional manufacturing process is particularly difficult to manufacture with high consistency and realize fully-connected leads for thousands of array elements.

Disclosure of Invention

The invention aims to provide an image sonar receiving array based on a piezoelectric micro-mechanical ultrasonic transducer (PMUT) and a manufacturing method thereof, which aim to solve the problems of high-consistency manufacturing of array elements and full connection of the array elements of the conventional image sonar receiving array.

In order to achieve the aim, the image sonar receiving array based on the PMUT is characterized by comprising a pressure-bearing shell, a PMUT module, a PCB adapter plate and an electronic bin; the PMUT modules are uniformly distributed on the PCB adapter plate to form an array, and are connected with the PCB adapter plate through pin pads of the PMUT modules, the PCB adapter plate is connected with the electronic cabin through a signal transmission interface, the pressure-bearing shell covers the PMUT modules, and the pressure-bearing shell is bonded with the PCB adapter plate through pouring sealant; the PMUT module comprises a tube shell and a PMUT chip packaged in the tube shell, wherein the PMUT chip comprises uniformly distributed PMUT array elements, the packaged PMUT module forms a cavity area on the surface of the PMUT chip, and the PMUT array elements are exposed so as to realize the reception of sound wave signals; and a cavity between the PMUT module and the pressure-bearing shell is filled with coupling agent.

Furthermore, in the image sonar receiving array, the PCB adapter plate includes an array composed of m × n uniformly distributed PMUT modules, that is, an array composed of m rows and n columns of PMUT modules, where m and n are positive integers. The PMUT chip typically includes uniformly distributed i × j PMUT array elements, i.e., an array of i rows and j columns of array elements, where i and j are positive integers. Each array element is composed of one or more PMUT micro-elements. Therefore, the image sonar receiving array includes a PMUT receiving array composed of m · i × n · j PMUT array elements (where m, n, i, and j are positive integers).

Specifically, if m · i and n · j are both greater than 1, the constructed PMUT receiving array is a two-dimensional area array and can be used for 3D image sonar; if one of m · i and n · j is equal to 1, and the other is greater than 1, the formed PMUT receiving array is a one-dimensional linear array and can be used for a 2D image sonar receiving array.

The PMUT array element size is determined by the directivity requirements of the image sonar for the unit array elements in the horizontal and vertical directions, and the PMUT array element spacing is generally determined by the beam pattern after beam forming.

Particularly, if i and j are equal to 1, namely each PMUT module only comprises one PMUT array element, the formed PMUT receiving array is a uniform array, wherein the intervals of all array elements are equal, the receiving array is suitable for a direct waveform beam forming algorithm during imaging, and all array elements can be divided into subarrays and then used for imaging; if i and j are not equal to 1 at the same time, the PMUT receiving array is a non-uniform array, sub-array division needs to be carried out on the receiving array when a beam forming algorithm is used for imaging, and the minimum unit of the sub-array is a PMUT module.

Furthermore, the image sonar receiving array based on the PMUT can adopt a manufacturing process or an integrated packaging technology which is based on the MEMS technology and compatible with the IC, thereby greatly simplifying the subsequent processing circuit. In the PMUT module, one way is to integrally manufacture an IC circuit on a PMUT chip, and the other way is to integrally package the IC chip and the PMUT chip into the PMUT module by adopting a mature three-dimensional stacked packaging scheme. The IC circuit or IC chip is mainly used for amplifying and filtering the PMUT signal.

Further, in the PMUT module, the package of the package can adopt various small-sized package forms such as DFN, QFN, LGA and the like. In order to meet the requirement of pressure resistance, the tube shell can be made of metal or ceramic materials capable of bearing larger pressure.

Specifically, based on the MEMS (Micro-Electro-Mechanical systems) process, the PMUT serving as the receiving transducer in the present invention has a basic structural unit of PMUT Micro element. As a form common in the art, the PMUT micro-element includes a substrate silicon, a top layer silicon, a lower electrode, an upper electrode and a piezoelectric layer, wherein the lower electrode, the upper electrode and the piezoelectric layer are partially etched to form a vibrating membrane, the substrate silicon is partially etched to form a cavity structure below the top layer silicon, and the vibrating membrane and the corresponding cavity structure form a PMUT micro-element.

Optionally, the PMUT micro-element is circular, rectangular or other polygonal shape. The characteristics of the sensitivity, bandwidth, acoustic impedance and the like of the PMUT micro element can be optimized through structural design, material improvement and the like.

As a basic functional unit of the PMUT chip, the PMUT array element comprises a PMUT micro element or a plurality of parallel PMUT micro elements. The upper electrodes of all the PMUT micro elements are connected through leads among the PMUT micro elements in the PMUT array elements, and all the PMUT micro elements share the lower electrode, so that the parallel connection of all the PMUT micro elements in the PMUT array elements is realized.

In the PMUT chip, the upper and lower electrodes of the PMUT array element are led out to a bonding pad of the PMUT chip through a lead of the PMUT chip.

In the PMUT module, after a PMUT chip is bonded and cured with a tube shell, a bonding pad of the PMUT chip is connected with a pin bonding pad on the tube shell by a bonding lead in a lead bonding mode, and the bonding lead is sealed and protected by pouring sealant; when the integrated packaging with the IC chip is adopted, the IC chip is firstly bonded with the tube shell, then the PMUT chip is bonded with the IC chip, the bonding lead is respectively used for connecting the IC chip bonding pad with the pin bonding pad on the tube shell and connecting the PMUT chip bonding pad with the IC chip bonding pad, and the bonding lead is sealed and protected by the pouring sealant.

The PCB adapter plate can be selected and adopted according to the PMUT module. The pin bonding pad of the PMUT module and the PCB adapter plate can be connected by soldering, which is determined by the pin mode of the PMUT module, and the alignment and soldering accuracy can be improved by soldering with a common reflow soldering device and a jig. The back of the PCB adapter plate is provided with a signal transmission interface for connecting the electronic cabin.

The electronic bin comprises an amplifying circuit, a filtering circuit, a collecting circuit, a storing circuit, a module or a chip, the functions of amplifying, filtering, collecting and storing signals received by each PMUT array element are realized, and corresponding interfaces are provided on the front surface and the back surface of the electronic bin and are respectively connected with the PCB adapter plate and an external control system.

The back of the pressure-bearing shell is provided with a cavity, the length and width of the cavity are larger than those of the PMUT module array, and the height of the cavity is smaller than that of the PMUT module. After the pressure-bearing shell is bonded with the PCB adapter plate, the pipe shell of the PMUT module is in hard contact with the pressure-bearing shell so as to transfer strong pressure from the pressure-bearing shell during deep water work, thereby avoiding the damage of the PMUT chip. The pressure-bearing shell is usually made of a material with acoustic impedance close to that of water, small acoustic attenuation and corrosion resistance, and specifically comprises materials such as polyvinyl chloride, polystyrene and organic glass.

The coupling agent can be selected according to conditions of acoustic impedance matching, acoustic attenuation, fluidity and the like.

The invention also relates to a method for manufacturing the image sonar receiving array based on the PMUT, which comprises the following steps:

1) PMUT chip fabrication

The PMUT chip comprises uniformly distributed PMUT array elements, the PMUT array elements comprise one or more PMUT micro elements connected in parallel, and the PMUT micro elements comprise substrate silicon, top layer silicon, a lower electrode, an upper electrode and a piezoelectric layer; depositing a lower electrode, a piezoelectric layer and an upper electrode on an SOI material, patterning the lower electrode, the piezoelectric layer and the upper electrode respectively, leading out the upper electrode and the lower electrode to a bonding pad of a PMUT chip respectively through a lead of the PMUT chip, and etching substrate silicon to form a cavity structure;

or, further, fabricating IC circuitry on the PMUT chip;

2) the packaging of the PMUT module bonds and solidifies the PMUT chip and the tube shell, a bonding wire is adopted to connect a bonding pad of the PMUT chip and a pin bonding pad on the tube shell by a bonding wire bonding mode, and the bonding wire is sealed and protected by pouring sealant; after packaging, the PMUT module forms a cavity on the surface of the PMUT chip, and the PMUT array element is exposed;

or when the IC chip is packaged in an integrated mode, firstly, the IC chip is bonded and cured with the tube shell, then, the PMUT chip is bonded and cured with the IC chip, the bonding lead is respectively used for connecting the IC chip bonding pad with the pin bonding pad on the tube shell, and the PMUT chip bonding pad with the IC chip bonding pad, and the bonding lead is sealed and protected by pouring sealant; after packaging, the PMUT module forms a cavity on the surface of the PMUT chip, and the PMUT array element is exposed;

3) connection of PMUT module, PCB adapter plate and electronic cabin

Arranging the PMUT modules on a PCB adapter plate to form an array, and connecting the array through pin pads on the back of a tube shell of the PMUT modules and corresponding pads on the front of the PCB adapter plate; connecting a signal transmission interface between a PCB adapter plate of the integrated PMUT module array and the electronic cabin;

4) pressure-bearing shell encapsulation

Firstly, a couplant is added into a cavity of each PMUT module in the PMUT module array, pouring sealant is coated on an outer frame area of the PCB adapter plate, and then a pressure-bearing shell covers the PMUT modules and is bonded.

Compared with the prior art, the invention has the beneficial effects that:

the invention adopts the PMUT manufactured by the MEMS (Micro-Electro-Mechanical System) process as the receiving transducer, which has the advantages of small volume, wide frequency band, good consistency, flexible frequency control, batch manufacturing and the like, and simultaneously, the PMUT can be integrally manufactured or integrally packaged with the IC, thereby greatly reducing subsequent processing circuits and effectively improving the signal quality; in addition, the modular PMUT packaging scheme provided by the invention can effectively solve the problem of large-scale array full-connection leads.

Drawings

FIG. 1 is a schematic structural diagram of a PMUT-based image sonar receiving array according to the present invention;

FIG. 2 is a cross-sectional view of a PMUT-based image sonar receiving array of the present invention;

FIG. 3 is a partial enlarged view of portion A of FIG. 2;

FIG. 4 is a schematic diagram of a PMUT micro-element structure;

FIG. 5 is a schematic diagram of a PMUT chip according to the present invention;

FIG. 6 is a schematic diagram of a linear array PMUT chip structure according to the present invention;

FIG. 7 is a schematic structural view of a linear array PMUT graphical sonar receiving array of the present invention;

FIG. 8 is a schematic diagram of a first type of PMUT module package according to the present invention;

fig. 9 is a schematic diagram of a second PMUT module package according to the present invention.

In the figure: the device comprises a 1-PMUT module, a 2-PCB adapter plate, a 3-electronic cabin, a 4-pressure-bearing shell, a 5-couplant, a 6-pouring sealant, a 7-electronic cabin communication interface, an 8-signal transmission interface, a 9-tube shell, a 10-PMUT chip, an 11-bonding lead, a 12-pin bonding pad, a 13-PMUT chip bonding pad, a 14-IC chip bonding pad, a 15-IC chip, a 16-PMUT chip lead, a 17-PMUT micro element, 18-top layer silicon, a 19-lower electrode, a 20-upper electrode, a 21-piezoelectric layer and 22-substrate silicon.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the following specific examples are illustrative only and are not intended to limit the invention. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.

According to the image sonar receiving array based on the PMUT, as shown in FIGS. 1 to 3, the image sonar receiving array sequentially comprises a laminated pressure-bearing shell 4, a group of PMUT modules 1, a PCB adapter plate 2 and an electronic bin 3 from top to bottom; the PMUT module 1 is evenly distributed on the PCB adapter plate 2 to form an array, the PCB adapter plate 2 is welded with a corresponding pad on the front side of the PCB adapter plate 2 through a pin pad on the back side of the PCB adapter plate, signal transmission interfaces 8 are arranged on the back side of the PCB adapter plate 2 and the front side of the electronic bin 3, the PCB adapter plate 2 is fixedly connected with the electronic bin 3 through the signal transmission interfaces 8, the pressure-bearing shell 4 covers the PMUT module 1, a cavity between the PMUT module 1 and the pressure-bearing shell 4 is filled with a coupling agent 5, and the pressure-bearing shell 4 is fixedly bonded with the PCB adapter plate 2 through a pouring sealant 6 such as epoxy resin.

Specifically, in the image sonar receiving array, the PCB interposer 2 includes an array of m × n uniformly distributed PMUT modules 1, that is, the array is composed of m rows and n columns of PMUT modules 1. The PMUT module 1 is a modular PMUT device packaged from PMUT chips 10, the PMUT chips 10 usually consist of i × j evenly distributed PMUT array elements, i.e. i rows and j columns of PMUT array elements, each of which may consist of one or more PMUT micro-elements. Therefore, the image sonar receiving array includes a PMUT receiving array composed of m · i × n · j PMUT array elements (m, n, i, j are positive integers).

It is understood that if m · i and n · j are both greater than 1, the PMUT receiving array is a two-dimensional area array and can be used for a 3D image sonar; if m & i is equal to 1 and n & j is greater than 1, the PMUT receiving array is a one-dimensional linear array and can be used for a 2D image sonar receiving array.

In the PMUT chip 10, the PMUT array element size is determined by the requirement for directivity of the unit array element in the horizontal and vertical directions from the image sonar, and the PMUT array element pitch d is generally determined by the beam pattern after beam forming.

Particularly, if i and j are equal to 1, that is, the PMUT module 1 only includes one PMUT array element, the formed PMUT receiving array is a uniform array, that is, the intervals of all array elements of the receiving array are equal, the receiving array is suitable for a direct waveform forming algorithm during imaging, and all array elements can be used for imaging after being subjected to subarray division; if the i and j are not uniform and equal to 1, the PMUT receiving array is a non-uniform array, and when a beam forming algorithm is used for imaging, the receiving array needs to be sub-array divided, and the minimum unit of the sub-array is a PMUT module 10.

In the following embodiments of the present invention, the PMUT chip 10 and PMUT module 1, PCB interposer 2, electronics pod 3, and pressure-bearing housing 4 are designed and manufactured according to the spirit and scope of the invention.

The basic functional units of the PMUT chip 10 constituting the PMUT receive array are array elements, which include one or more elementary structural units, namely, micro-elements. In the field of micro-electro-mechanical systems (MEMS), as shown in fig. 4, the PMUT micro-element generally comprises a substrate silicon 22, a top layer silicon 18, a lower electrode 19, an upper electrode 20, a piezoelectric layer 21, etc., wherein the lower electrode 19, the upper electrode 20, and the piezoelectric layer 21 are partially etched to form a vibrating membrane with a desired shape and size, the substrate silicon 22 is partially etched to form a cavity structure below the top layer silicon 18, and the vibrating membrane and the corresponding cavity structure form a PMUT micro-element. The PMUT primitives may be circular, rectangular, or other polygonal shapes. The characteristics of sensitivity, bandwidth, acoustic impedance and the like of the PMUT micro element can be optimized through structural design, material improvement and the like.

Referring to fig. 4 and 5, the PMUT chip 10 mainly includes PMUT array elements of i × j uniform distribution, where the PMUT array elements include one or more PMUT micro elements. The upper electrodes of all the micro elements are connected through leads between the micro elements in the PMUT array element, and all the micro elements share the lower electrode, so that all the PMUT micro elements in the array element are connected in parallel. The PMUT chip 10 is manufactured by using the processes of photolithography, etching, deposition and the like in the existing MEMS process, and mainly through the following process flows: firstly, depositing a lower electrode 19, a piezoelectric layer 21 and an upper electrode 20 on an SOI material, then respectively patterning the lower electrode 19, the piezoelectric layer 21 and the upper electrode 20, respectively leading out the upper electrode and the lower electrode to a PMUT chip bonding pad 13 of a frame of a PMUT chip 10 through a PMUT chip lead 16, and finally etching substrate silicon 22 to form a cavity structure.

One specific example is as shown in fig. 5, which is a PMUT chip 10 with 3 × 3 array elements, i.e., i is 3, j is 3, each array element is composed of 16 PMUT micro-elements 17, such an area PMUT chip can form an area array receiving array, mainly used for 3D image sonar, each array element of the receiving array is symmetrical in the horizontal and vertical directions, so as to ensure that the array elements have the same directivity in the horizontal and vertical directions.

Another specific example is shown in fig. 6, which is a schematic diagram of a conventional linear array PMUT chip 10 array element, and since the 2D image sonar has different requirements for directivity of the receiving array element in the horizontal and vertical directions, the array element has an asymmetric structure in the horizontal and vertical directions. Fig. 7 is a schematic view showing a linear array PMUT image sonar receiving array structure according to the present invention, which is mainly used for 2D image sonar, and the manufacturing process is similar to the above-mentioned 3D image sonar receiving array.

The PMUT chip 10 is packaged by a modularized PMUT to obtain the PMUT module 1, the PMUT chip 10 is packaged by a tube shell 9, and a cavity area is arranged on the surface of the PMUT chip 10 to expose PMUT array elements on the PMUT chip 10.

Specifically, the package of the package 9 can adopt various small-sized package forms such as DFN, QFN, LGA, etc., and in order to meet the requirement of pressure resistance, the package 9 adopts a material capable of bearing a large pressure, such as metal or ceramic, etc.

Furthermore, the image sonar receiving array based on the PMUT is processed by adopting the MEMS technology, and the PMUT can be manufactured by adopting a manufacturing process compatible with an IC, and is manufactured or packaged integrally with a front-end circuit, so that a subsequent processing circuit can be greatly simplified. One way is to integrally fabricate the IC circuitry on the PMUT chip 10, and the other way is to integrally package the IC chip and PMUT chip into a PMUT module using a more sophisticated three-dimensional stacked packaging scheme. The IC circuit or the IC chip is mainly used for amplifying and filtering the PMUT signals.

Specifically, as shown in fig. 8, a PMUT module 1 is packaged, a PMUT chip 10 is aligned and bonded to a case 9, and after the PMUT chip 10 is cured, a PMUT chip bonding pad 13 is connected to a case bonding pad 12 by a bonding wire 11 in a wire bonding manner; or another PMUT module 1 package is as shown in fig. 9, integrally packaging an IC chip 15 and a PMUT chip 10 into the PMUT module 1, aligning and bonding the IC chip 15 and a case 9, aligning and bonding the PMUT chip 10 and the IC chip 15, and then connecting an IC chip bonding pad 14 and a case bonding pad 12 and connecting a PMUT chip bonding pad 13 and an IC chip bonding pad 14 by using a bonding wire 11 respectively; and finally, sealing and protecting the bonding lead 11 by using high-temperature-resistant pouring sealant. The surface of the finally formed PMUT module 1 has a cavity region, so that PMUT array elements on the PMUT chip 10 are exposed, and the reception of acoustic wave signals is realized.

After the packaging of the PMUT module 1 is completed, the PMUT module 1 is connected with the PCB adapter plate 2 and the electronic cabin 3, and finally the pressure-bearing shell 4 is packaged, so that the image sonar receiving array based on the PMUT is realized.

The PMUT modules 1 are distributed on the PCB adapter plate 2 to form an array, the PMUT modules 1 and the PCB adapter plate 2 are aligned and welded through the connection of the tube shell welding pads 12 on the back side of the PMUT modules and the corresponding welding pads on the front side of the PCB adapter plate 2, the welding mode is determined by the pin mode of the PMUT modules 1, reflow soldering is commonly adopted, and devices such as clamps and the like can be adopted during welding to improve the alignment and welding precision.

Further, the PCB adapter plate 2 integrated with the array of the PMUT module 1 and the electronic cabin 3 are welded, and the welding mode can adopt reflow soldering. The electronic cabin 3 internally comprises chips for amplifying, filtering, collecting and storing echo signals received by each PMUT array element, the chips are integrally packaged in a pressure-resistant shell, a signal transmission interface 8 corresponding to the PCB adapter plate 2 is arranged on the upper surface of the shell, and an electronic cabin communication interface 7 for communicating with the outside and transmitting data is arranged on the lower surface of the shell. And (3) encapsulating the electronic cabin 3 by using high-temperature encapsulating glue so as to meet the pressure-resistant requirement of underwater use.

To complete the PMUT-based image sonar receiving array, the pressure-bearing housing 4 is finally encapsulated on its front side. The pressure-bearing shell 4 is made of a material which is waterproof, wear-resistant, pressure-resistant, close in acoustic impedance to water and small in acoustic attenuation, and can be specifically formed by pouring materials such as polyvinyl chloride, polystyrene and organic glass by using a mold, as shown in fig. 2, a cavity is arranged on the back surface of the pressure-bearing shell 4, the length and the width of the cavity are larger than those of the array of the PMUT module 1, and the height of the cavity is smaller than that of the PMUT module 1.

When packaging is carried out, firstly, a couplant 5 is added into a cavity of each PMUT module 1 in the PMUT module 1 array, and the couplant 5 is usually made of grease or other pasty couplants.

Specifically, the PMUT module 1 array is placed in a heatable dispensing system, the couplant 5 and the PMUT module 1 array are heated to a temperature above the dropping point of the couplant 5 and dropped into the central area of the cavity of each PMUT module 1, and the volume of the added couplant is slightly smaller than the volume of the cavity. Further, the array of the PMUT modules 1 and the pressure-bearing shell 4 are fixed on a fixture at a horizontal angle, pouring sealant 6 is coated on the outer frame area of the PCB adapter plate 2 of the receiving array, and then the array of the PMUT modules 1 and the pressure-bearing shell 4 are aligned and bonded.

The couplant in the cavity of the PMUT module 1 is uniformly filled in an array element area under the pressure action of the pressure-bearing shell 4, and the couplant basically does not flow in a working temperature interval, so that a good coupling effect is ensured between the PMUT chip 10 and the pressure-bearing shell 4, and sound transmission is realized.

In the above encapsulation, the hard contact between the tube shell 9 of the PMUT module 1 and the pressure-bearing shell 4 can be realized to transmit the strong pressure from the pressure-bearing shell 4 during deep water work, so that the PMUT chip 10 is prevented from being damaged.