Piezoelectric film packaging structure, packaging process and space dust momentum measurement system

Abstract

The invention discloses a piezoelectric film packaging structure which comprises a shell, a fixing plate, a first electrode layer, a piezoelectric film, a second electrode layer and a bottom plate. The first electrode layer and the second electrode layer are arranged on the two sides of the piezoelectric film respectively; the fixing plate and the bottom plate are respectively arranged on the surfaces of the first electrode layer and the second electrode layer; the fixed plate, the first electrode layer, the piezoelectric film, the second electrode layer and the bottom plate are fastened through a first fastening assembly to form a core module; and the shell is arranged on the fixing plate and is fastened with the core module through a second fastening assembly to form the packaging structure. A wrinkle removing part and a reinforcing part extend out of one side, facing the piezoelectric film, of the shell; the wrinkle removing part abuts against the piezoelectric film in the direction of the bottom plate. The reinforcing part surrounds the outer side of the core module. The invention further discloses a piezoelectric thin film packaging process, and the packaging structure is adopted in the piezoelectric thin film packaging process. The invention further discloses a space dust momentum measuring system. Two groups of packaging structures which are designed in a differentiated mode are adopted in a sensing assembly of the measuring system.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor equipment, and in particular to a packaging structure and packaging process of a piezoelectric film and a piezoelectric sensing space dust momentum measurement system. Background Art

[0002] With the continuous advancement of science and technology and the increasing demand for precision instruments, piezoelectric film sensors have been widely used in many fields due to their excellent performance. This type of sensor uses piezoelectric materials such as polyvinylidene fluoride (PVDF) to convert mechanical shock, pressure or vibration into electrical signals through the piezoelectric effect. It has the significant advantages of high sensitivity, fast response and low energy consumption. It has been successfully applied to vibration detection, pressure sensing and other scenarios in industrial automation, environmental monitoring, medical equipment and other fields, and even shows unique value in the aerospace field.

[0003] However, although piezoelectric film sensors have significant advantages in performance, their stability and reliability in practical applications are challenged due to the fact that they often use very thin materials in their structure. The film material itself is relatively soft and has insufficient support, so it is easily affected by stress during the assembly process, causing the film to wrinkle and deform. The wrinkles of the film not only affect its working performance and reduce the sensitivity of the sensor, but may also cause errors in the output of the electrical signal, thereby affecting the measurement accuracy of the entire sensor. Traditional packaging methods are difficult to completely eliminate the wrinkles caused by the flexibility of the film material and assembly errors.

[0004] The need to break through this technical bottleneck is of great practical significance, especially in the field of space dust momentum measurement. As tiny particles dispersed in the universe, the kinetic energy generated by space dust at high speed is enough to cause material erosion, structural damage and even functional failure to the surface materials and precision components of spacecraft. At present, the measurement system based on high-sensitivity piezoelectric film sensors has become the core means to monitor the momentum, flux and distribution characteristics of space dust. However, the wrinkles on the surface of the piezoelectric film will cause signal distortion, significantly reduce the resolution accuracy of key parameters such as dust momentum and flux, and may even lead to systematic deviations in space environment assessment. Therefore, the development of piezoelectric film sensing technology with excellent structural stability has become a key issue that needs to be urgently solved in this field. Summary of the invention

[0005] The main technical problem to be solved by the present invention is to provide a piezoelectric film packaging structure, which can eliminate the wrinkle defects of the piezoelectric film through a more reliable and stable flatness control structure while ensuring efficient charge conduction, thereby improving the working performance of the piezoelectric sensor.

[0006] To solve the above technical problems, the present invention provides a piezoelectric thin film encapsulation structure, including a housing, a fixing plate, a first electrode layer, a piezoelectric thin film, a second electrode layer, a bottom plate, a first fastening component and a second fastening component;

[0007] The first electrode layer and the second electrode layer are respectively disposed on both sides of the piezoelectric thin film; the fixing plate is disposed on the side of the first electrode layer facing away from the piezoelectric thin film; the bottom plate is disposed on the side of the second electrode layer facing away from the piezoelectric thin film; the fixing plate, the first electrode layer, the piezoelectric thin film, the second electrode layer and the bottom plate are fastened along the thickness direction by the first fastening component to jointly form a core module; the housing is disposed on the side of the fixing plate facing away from the piezoelectric thin film and is fastened along the thickness direction with the core module by the second fastening component to jointly form the encapsulation structure;

[0008] The housing extends a wrinkle removal portion on the side facing the piezoelectric thin film; the vertical distance from the wrinkle removal portion to the bottom plate is less than the thickness of the second electrode layer to abut against the piezoelectric thin film in the direction of the bottom plate; the housing also extends a reinforcing portion on the same side as the wrinkle removal portion, and the reinforcing portion encloses the outside of the core module.

[0009] In a preferred embodiment, the material of the wrinkle removal portion is a conductive material; the encapsulation structure further includes an insulating film;

[0010] The insulating film is disposed between the first electrode layer and the fixing plate; the insulating film extends to the inside of the wrinkle removal portion towards the geometric center to isolate the wrinkle removal portion from the piezoelectric thin film.

[0011] In a preferred embodiment, the first electrode layer is an electrode made of a flexible printed circuit board.

[0012] In a preferred embodiment, the second electrode layer is an electrode made of a rigid printed circuit board.

[0013] In a preferred embodiment, the encapsulation structure further includes an electrode lead-out member for externally outputting the charges collected by the first electrode layer and the second electrode layer; the electrode lead-out member is fixed on the lead-out area extending from the first electrode layer and the second electrode layer.

[0014] In a preferred embodiment, the wrinkle removal portion is configured to be circular.

[0015] In a preferred embodiment, the housing and the bottom plate are made of aluminum alloy material.

[0016] The present invention also provides a piezoelectric thin film encapsulation process, which adopts the piezoelectric thin film encapsulation structure described above. The encapsulation process includes the following steps:

[0017] Step 1: Stack the fixed plate, the first electrode layer, the piezoelectric film, the second electrode layer, and the bottom plate in sequence, and align with the hole positions of the first fastening component;

[0018] Step 2: Use the first fastening component to pass through the fixed plate, the first electrode layer, the piezoelectric film, the second electrode layer, and the bottom plate in the thickness direction and then fasten them to form the core module;

[0019] Step 3: Place the housing on the surface of the fixed plate, and adjust the position to align with the hole positions of the second fastening component; the side of the housing where the wrinkle removal part and the reinforcement part extend faces the fixed plate;

[0020] Step 4: Use the second fastening component to fasten the housing and the core module in the thickness direction to form the encapsulated structure; during the fastening process, observe and calibrate the pressing state of the wrinkle removal part against the piezoelectric film.

[0021] The present invention also provides a spatial dust momentum measurement system, including a sensing component; the sensing component is equipped with the piezoelectric film encapsulated structure described above.

[0022] In a preferred embodiment, the sensing component includes a first sensing unit and a second sensing unit; the first sensing unit and the second sensing unit adopt the encapsulated structure;

[0023] The area of the piezoelectric film in the first sensing unit is larger than that of the piezoelectric film in the second sensing unit; the thickness of the piezoelectric film in the first sensing unit is greater than that of the piezoelectric film in the second sensing unit.

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] Through innovative mechanical design and material combination, the present invention constructs a piezoelectric thin film packaging structure that combines high sensitivity, long life cycle, and low maintenance cost, providing a breakthrough solution for the field of precision measurement. Specifically: (1) Through the precise structural cooperation between the wrinkle-removing ring and the PCB electrode, the packaging structure actively removes mechanical wrinkles from the piezoelectric thin film, eliminating the wrinkle defects caused by film relaxation in traditional processes, improving the response sensitivity of the piezoelectric effect and the charge distribution uniformity. This flatness control method simplifies the production process significantly while ensuring process stability. (2) In the design of the electrode layer, the PCB electrode film provides a stable substrate support; the FPC electrode cooperates with the PCB electrode to ensure the charge collection efficiency with the piezoelectric thin film. At the same time, its bendable property provides an operating surface for replacing the piezoelectric thin film, improving the maintainability of the device, and making the packaging structure have both high working performance and usability. (3) The packaging structure also enhances the overall reliability through multi-level rigid strengthening design of the PCB board, fixing plate, bottom plate, outer shell, and the reinforcing ring thereon, significantly reducing the bending risk during the assembly process.

[0026] In the space dust momentum measurement system provided by the present invention, the sensing component applies the above packaging structure, having higher response speed and working stability. In addition, the measurement system is equipped with two groups of packaging structures with differential designs, providing targeted solutions for dust particles with different characteristics and dust environments with different fluxes, avoiding the performance limitations of a single sensor in variable working scenarios. Therefore, the measurement system can not only capture more three-dimensional and accurate data samples but also has a wider applicability. Description of the Drawings

[0027] Figure 1 It is an exploded view of the piezoelectric thin film packaging structure in Embodiment 1 of the present invention;

[0028] Figure 2 It is an overall view of the piezoelectric thin film packaging structure in Embodiment 1 of the present invention;

[0029] Figure 3 It is a sectional view of the piezoelectric thin film packaging structure in Embodiment 1 of the present invention (the dimensions of the components in the figure are only for illustration and do not represent the relative relationship of actual dimensions);

[0030] Figure 4 It is a structural view of the outer shell in Embodiment 1 of the present invention:

[0031] Figure 5 It is a plan view of the FPC electrode in Embodiment 1 of the present invention;

[0032] Figure 6 It is a plan view of the PCB electrode in Embodiment 1 of the present invention;

[0033] Figure 7 Schematic diagram of the pre-tension of the piezoelectric film described in Embodiment 1 of the present invention (the arrow in the figure indicates the direction of the pre-tension);

[0034] Figure 8 Cross-sectional schematic diagram of the piezoelectric film packaging structure described in Embodiment 2 of the present invention (the dimensions of the components in the figure are only for illustration and do not represent the relative relationship of the actual dimensions);

[0035] Figure 9 Schematic flow chart of the piezoelectric film packaging process described in Embodiment 3 of the present invention;

[0036] Figure 10 Schematic diagram of the composition of the space dust momentum measurement system described in Embodiment 4 of the present invention;

[0037] Figure 11 Schematic diagram of the composition of the signal processing circuit described in Embodiment 4 of the present invention.

[0038] 1 - housing, 101 - reinforcing ring, 102 - wrinkle-removing ring, 103 - lead-out notch, 2 - fixing plate, 3 - PI film, 4 - FPC electrode, 401 - FPC assembly area, 402 - FPC electrode area, 403 - FPC lead-out area, 5 - piezoelectric film, 6 - PCB electrode, 601 - PCB assembly area, 602 - PCB electrode area, 603 - PCB lead-out area, 7 - bottom plate, 8 - 2Pin socket, 901 - first screw group, 902 - second screw group, 10 - sensing assembly, 1001 - first sensing unit, 1002 - second sensing unit, 11 - signal processing circuit, 1101 - charge sensitive amplifier, 1102 - amplifier circuit, 1103 - shaping circuit, 1104 - peak holding circuit, 12 - host computer. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "top / bottom end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "provided with", "sheathed / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a wall-mounted connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium. It can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Embodiment 1

[0043] As Figures 1 to 7 shown, the embodiment of the present invention provides a piezoelectric thin film encapsulation structure, including a housing 1, a fixing plate 2, an insulating film, a first electrode layer, a piezoelectric thin film 5, a second electrode layer, a bottom plate 7, an electrode lead-out member, a first fastening assembly, and a second fastening assembly. In this embodiment, the insulating film is specifically a polyimide film (hereinafter referred to as the PI film 3), the first electrode layer is an electrode made of a flexible printed circuit board (hereinafter referred to as the FPC electrode 4), the second electrode layer is an electrode made of a rigid printed circuit board (hereinafter referred to as the PCB electrode 6), and the electrode lead-out member is a 2Pin socket 8 with two-phase pins. The first fastening assembly and the second fastening assembly are specifically screws, hereinafter referred to as the first screw group 901 and the second screw group 902 respectively.

[0044] The fixing plate 2, the FPC electrode 4, the PCB electrode 6, and the bottom plate 7 adopt an annular structure with an outer diameter equal to that of the piezoelectric thin film 5. As Figures 1 to 3As shown, overall, the FPC electrode 4 and the PCB electrode 6 are respectively arranged on both sides of the piezoelectric film 5 to collect the charges generated by the piezoelectric effect of the piezoelectric film 5. The FPC electrode 4 and the PCB electrode 6 extend out the lead-out area along the radial direction at the same circumferential position, and the 2Pin socket 8 is welded to the lead-out area to achieve the output of the electrical signal. The fixing plate 2 is arranged on the side of the FPO electrode 4 facing away from the piezoelectric film 5; the bottom plate 7 is arranged on the side of the PCB electrode 6 facing away from the piezoelectric film 5. The fixing plate 2, the FPC electrode 4, the piezoelectric film 5, the PCB electrode 6, and the bottom plate 7 are fastened along the thickness direction through the threaded cooperation of the first screw group 901 and the bottom plate 7, jointly constituting a core module that can generate and conduct charge signals. The housing 1 is fastened to the bottom plate 7 through the second screw group 902 from the side of the fixing plate 2 facing away from the piezoelectric film 5, providing electromagnetic shielding and rigid support for the core module. The housing 1 extends a closed reinforcing part and a wrinkle-removing part on the side facing the piezoelectric film 5. In this embodiment, to match the annular core module, the reinforcing part and the wrinkle-removing part are configured as circular shapes, and are respectively referred to as the reinforcing ring 101 and the wrinkle-removing ring 102 hereinafter. The wrinkle-removing ring 102 abuts against the piezoelectric film 5 in the direction of the bottom plate 7, causing the piezoelectric film 5 to generate elastic radial pre-tension and be tightened. The reinforcing ring 101 encloses the outside of the core module, playing a role of protection.

[0045] Both the first screw group 901 and the second screw group 902 pass through the FPC electrode 4, the piezoelectric film 5, and the PCB electrode 6 at the same time. It should be understood that in other embodiments, only relying on the first screw group 901 passing through the FPC electrode 4, the piezoelectric film 5, and the PCB electrode 6 at the same time can also stably fix the outer ring of the piezoelectric film 5 before tensioning.

[0046] In this embodiment, to provide better electromagnetic shielding and structural support, the housing 1 together with the wrinkle-removing ring 102 is made of metal material. To prevent charge leakage of the piezoelectric film 5 due to the wrinkle-removing ring 102, a layer of annular PI film 3 is further clamped between the FPC electrode 4 and the fixing plate 2. The PI film 3 extends towards the center of the circle to the inside of the wrinkle-removing ring 102, realizing the isolation between the piezoelectric film 5 and the wrinkle-removing ring 102. In other words, the inner diameter of the PI film 3 is not greater than the inner diameter of the wrinkle-removing ring 102.

[0047] Based on the above structural relationship, the technical advantages of the packaging structure will be further described below in combination with the specific structural configurations and connection methods of the above components.

[0048] As Figure 4As shown, the housing 1 is a rigid ring-shaped metal structure. A reinforcing ring 101 extends outwards along the normal direction on the outer circle, and the wrinkle-removing ring 102 extends outwards along the same direction on the inner circle. Compared with the planar structure of the reinforcing plate, the circumferentially extending reinforcing ring 101 improves the out-of-plane stiffness of the housing 1, endowing it with better bending resistance, greatly reducing the risk of bending during assembly and use of the traditional packaging structure, and also providing a stable skeleton support for the mechanical wrinkle removal of the wrinkle-removing ring 102. At the same time, as Figure 3 shown, the reinforcing ring 101 surrounds the outside of the core module, acting as an enclosure structure for the core module, performing functions such as anti-side collision, waterproofing, and electromagnetic shielding, and improving the working stability of the packaging structure. An extraction notch 103 is provided on the reinforcing ring 101 for installing the 2Pin socket 8.

[0049] The wrinkle-removing ring 102 and its mechanical wrinkle-removing effect on the piezoelectric film 5 are one of the core technical innovations of the embodiment of the present invention. As Figure 3 shown, when the housing 1 and the bottom plate 7 are fastened by the second screw group 902, the thickened PCB board supports the piezoelectric film 5 on the periphery, keeping a certain interval between the piezoelectric film 5 and the bottom. And the wrinkle-removing ring 102 abuts against the piezoelectric film 5 towards the bottom plate 7 at a position closer to the center of the circle, causing the piezoelectric film 5 to be configured into a concave-convex shape and elastically tensioned, thereby generating a radial pre-tension, as Figure 7 shown. This pre-tension state brings two advantages: it eliminates the inherent wrinkles of the piezoelectric film 5 in the relaxed state. The tightened state not only enables the piezoelectric film 5 to be in the best response state, capable of quickly exciting the piezoelectric effect when subjected to a small external force, but also ensures uniform charge distribution when the piezoelectric film 5 is stressed. Compared with the traditional chemical coating or complex heat treatment methods, the packaging structure realizes the wrinkle removal of the piezoelectric film 5 through the cooperation of mechanical structures, not only improving the stability of flatness control, but also simplifying the process and reducing the packaging investment.

[0050] From Figure 3 it can be known that if the thickness of the PI film 3 is ignored, the distance from the wrinkle-removing ring 102 to the bottom plate 7 should be less than the thickness of the PCB electrode 6. Preferably, in order to balance the wrinkle-removing effect of the piezoelectric film 5 and the risk of damage during assembly, in this embodiment, the relationship between the vertical distance t between the wrinkle-removing ring 102 and the fixing plate 2 and the diameter D of the sensitive area of the piezoelectric film 5 is: D / t = 120. The sensitive area is the middle circular area where the piezoelectric film 5 is not in contact with any of the above components. In this embodiment, it can be regarded as the projection area of the inner circle of the PI film 3 on the piezoelectric film 5. The t is the same-side distance between two rigid components, which is easy to control during production and assembly.

[0051] AsFigure 5 As shown, the FPC electrode 4 includes an FPC assembly area 401, an FPC electrode area 402, and an FPC lead-out area 403. The FPC assembly area 401 is arranged on the outer circle of the FPC electrode 4 and is preset with hole positions matching the bottom plate 7 for the first screw group 901 and the second screw group 902 to pass through. The FPC electrode area 402 is a bare copper electrode arranged on the inner circle of the FPC electrode 4, and its surface is subjected to immersion gold treatment to improve conductivity and corrosion resistance. The FPC assembly area 401 extends radially outward to form the FPC lead-out area 403. A pair of jacks are arranged in the FPC lead-out area 403, and one of the jacks (hereinafter denoted as the first jack) is connected to the FPC electrode area 402. As Figure 6 shown, the structure of the PCB electrode 6 is similar to that of the FPC, including a PCB assembly area 601 on the outer circle, a PCB electrode area 602 on the inner circle, and an extended PCB lead-out area 603. The surface of the PCB electrode area 602 is subjected to tin spraying treatment. A pair of jacks are also arranged in the PCB lead-out area 603, and one of the jacks (hereinafter denoted as the second jack) is connected to the PCB electrode area 602. The side of the FPC electrode 4 with the electrode area is attached to one side of the piezoelectric film 5 to collect positive charges; the side of the PCB electrode 6 with the electrode area is attached to the other side of the piezoelectric film 5 to collect negative charges. As Figure 1 shown, the pins of the 2Pin socket 8 pass through the lead-out areas of the FPC electrode 4 and the PCB electrode 6 at the same time and are welded and fixed to prevent relative displacement between the FPC electrode 4 and the PCB electrode 6. In terms of electrical connection, the two-phase pins of the 2Pin socket 8 are respectively connected to the misaligned first jack and the second jack, so as to export charges. When an external pressure acts on the surface of the piezoelectric film 5, the piezoelectric film 5 generates charges due to the piezoelectric effect. The FPC electrode 4 and the PCB electrode 6 capture positive and negative charges on both sides respectively, and conduct the charge signal outward through the 2Pin socket 8.

[0052] Preferably, in order to cooperate with the wrinkle-removing ring 102 with higher geometric accuracy and improve the overall stiffness of the core module, in this embodiment, the second electrode layer uses a rigid PCB electrode 6. It should be understood that if a rigid electrode is selected for the first electrode layer, it still does not affect the normal operation of the packaging structure and the innovative function of mechanical wrinkle removal. In this embodiment, the reason for selecting the first electrode layer as a flexible FPC electrode 4 is to achieve the following technical effects: (1) Cooperate with the rigid PCB electrode 6 to closely adhere to the piezoelectric film 5 to ensure the charge collection efficiency; (2) The piezoelectric film 5 is a consumable and needs to be replaced regularly. If rigid structures are used for both electrodes on both sides of the piezoelectric film 5, it is difficult to separate them after being welded and fixed by the 2Pin socket 8 to replace the piezoelectric film 5. Therefore, the first electrode layer uses a flexible FPC electrode 4 so as to be lifted when replacing the piezoelectric film 5, providing an operating surface for the disassembly and installation of the piezoelectric film 5. In summary, the above structure with a combination of rigid and flexible electrode layers improves the working performance and usability of the packaging structure.

[0053] In terms of material selection, the substrate of the FPC electrode 4 uses polyimide, which has good flexibility and insulation; the substrate of the PCB electrode 6 uses glass fiber, which has good stability and electrical performance. The fixing plate 2 is made of a glass fiber board processed by a milling process, with a thickness of 0.3 mm and good mechanical properties. The housing 1 is made of 6061 aluminum alloy processed by a numerical control process, and the bottom plate 7 is made of 6061 aluminum alloy processed by a laser cutting process, with high processing accuracy and excellent structural performance.

[0054] In summary, the piezoelectric film packaging structure provided by the embodiment of the present invention at least reflects three technical advantages:

[0055] The wrinkle-removing ring 102 extending from the housing 1 and the PCB electrode 6 are in precise geometric cooperation to apply a controllable radial pre-tension to the piezoelectric film 5, making the film sensitive area form a uniformly tensioned and tightened state. This active mechanical tensioning not only completely eliminates the wrinkle defects caused by film relaxation in the traditional process, but also improves the response sensitivity of the piezoelectric effect and the charge distribution uniformity by establishing a stable stress distribution. Compared with the traditional solutions that rely on chemical treatment or thermoforming, the packaging structure actively regulates the film morphology through a pure mechanical structure, greatly simplifying the production process while ensuring process stability.

[0056] In the design of the electrode layer, the original rigid-flexible structure architecture effectively balances the charge collection efficiency and the maintainability of the device. The PCB electrode 6 provides a stable base support for the thin film through a thickened ring structure. The FPC electrode 4, with excellent conformability, cooperates with the PCB electrode 6 to ensure the charge collection efficiency with the piezoelectric thin film 5. At the same time, the bendable characteristic of the FPC electrode 4 provides an operating surface for replacing the piezoelectric thin film 5, effectively solving the problem that it is not easy to lift the all-rigid electrode group, and significantly improving the maintainability of the device. This synergistic design of combining rigidity and flexibility endows the packaging structure with the dual advantages of high-precision signal acquisition and long-term stable operation.

[0057] The packaging structure also improves the overall reliability through a multi-level rigid reinforcement design. The PCB board, the fixing plate 2, and the bottom plate 7 all adopt rigid structures, and the structural strength of the core module is improved through multi-layer stacking. And the above-mentioned screw groups with hierarchical fastening realize the balanced distribution of stress in the core module. On this basis, the reinforcing ring 101 greatly improves the out-of-plane stiffness through a circumferential extension structure, significantly reducing the bending risk during the assembly process.

[0058] Therefore, through innovative mechanical design and material combination, the embodiment of the present invention constructs a new piezoelectric thin film packaging structure with high sensitivity, long life cycle and low maintenance cost, providing a breakthrough solution for the field of precision measurement.

[0059] Embodiment 2

[0060] As Figure 8 shown, the embodiment of the present invention provides a piezoelectric thin film packaging structure, which is different from Embodiment 1 in that: the wrinkle-removing ring 102 of the packaging structure is made of an insulating material. Therefore, there is no need to arrange the PI film 3 in the core module of the packaging structure to insulate the piezoelectric thin film 5. In other words, the side of the FPC electrode 4 facing away from the piezoelectric thin film is directly attached to the fixing plate 2, and the wrinkle-removing ring 102 directly abuts against the surface of the piezoelectric thin film 5.

[0061] Except for the above differences, the rest of the packaging structure provided in this embodiment is the same as that in Embodiment 1, and will not be elaborated here.

[0062] Embodiment 3

[0063] As Figure 9As shown in the figure, an embodiment of the present invention provides a packaging process for a piezoelectric thin film, which adopts the packaging structure provided in Embodiment 1 or 2. For the convenience of the following description, before introducing the assembly process, it is necessary to sort out the hole positions on the packaging structure that cooperate with the first screw group 901 and the second screw group 902. On the fixing plate 2, the PI film 3, the FPC electrode 4, the piezoelectric thin film 5, the PCB electrode 6, and the bottom plate 7, there are respectively provided a first hole position group and a second hole position group that are aligned with each other, for the first screw group 901 and the second screw group 902 to pass through respectively. On the outer shell 1, there is at least a matching second hole position group for the second screw group 902 to pass through. It should be noted that the first hole position group and the second hole position group on the bottom plate 7 are configured as threaded holes to perform threaded cooperation with the first screw group 901 and the second screw group 902. Preferably, in order to achieve the compactness inside the packaging structure in this embodiment, the outer shell 1 is provided with a relief through hole at the position corresponding to the first hole position group, and the screw head of the first screw group 901 is installed in the relief through hole. It is not difficult to understand that in other embodiments, the screw head of the first screw group 901 can also be installed in the counterbore of the fixing plate 2.

[0064] The packaging process includes the following steps:

[0065] Step 1: Stack the fixing plate 2, the PI film 3, the FPC electrode 4, the piezoelectric thin film 5, the PCB electrode 6, and the bottom plate 7 in sequence and align the hole positions on the outer periphery.

[0066] Step 2: Use the first screw group 901 to sequentially pass through the first hole position groups on the fixing plate 2, the PI film 3, the FPC electrode 4, the piezoelectric thin film 5, and the PCB electrode 6, and then the first screw group 901 is screwed into the threaded hole on the bottom plate 7 and tightened through threaded cooperation to clamp the above-mentioned layers of components to form the core module.

[0067] Step 3: Place the outer shell 1 on the surface of the fixing plate 2 and adjust the position to align the hole positions. It should be noted that the side of the outer shell 1 where the wrinkle-removing ring 102 and the reinforcement ring 101 extend faces the fixing plate 2.

[0068] Step 4: Use the second screw group 902 to pass through the second hole position groups of the outer shell 1 and the core module, and then the second screw group 902 is screwed into the remaining threaded holes on the bottom plate 7 to fix the outer shell 1 on the core module through threaded cooperation. During the tightening process of the second screw group 902, the abutting state of the wrinkle-removing ring 102 against the piezoelectric thin film 5 should be observed and calibrated to ensure that the piezoelectric thin film 5 is gradually tightened to achieve a better wrinkle-removing effect.

[0069] Step 5: Insert the pins of the 2Pin socket 8 into the lead-out areas of the FPC electrode 4 and the PCB electrode 6, and fix them by soldering.

[0070] So far, the assembly of the encapsulation structure is completed. It should be noted that, corresponding to Embodiment 2, if the wrinkle-removing ring 102 is made of insulating material, the PI film 3 does not need to be installed in Step 1.

[0071] Embodiment 4

[0072] As Figures 10 to 11 shown, an embodiment of the present invention provides a space dust momentum measurement system, including a sensing component 10, a signal processing circuit 11 and a host computer 12. The sensing component 10 applies the piezoelectric film encapsulation structure described in Embodiment 1 and Embodiment 2, so as to have higher response speed and working stability.

[0073] As Figure 10 shown, the sensing component 10 includes a first sensing unit 1001 and a second sensing unit 1002, and the first sensing unit 1001 and the second sensing unit 1002 adopt the above-mentioned encapsulation structure with differential design. Specifically, the working area of the piezoelectric film 5 in the first sensing unit 1001 is 50 cm 2 , and the thickness is 28 μm; the working area of the piezoelectric film 5 in the second sensing unit 1002 is 10 cm 2 , and the thickness is 7 μm. Relatively speaking, the first sensing unit 1001 has a larger area and can receive more dust particles. Combining with its relatively low resonance frequency, it has higher capture sensitivity in a low-flux dust environment, equivalent to the "wide-area detection network" of the sensing component 10. The second sensor has a smaller area and a thinner thickness, and its higher resonance frequency gives it higher spatial resolution, and it can more accurately measure the flux and distribution of particles in a high-flux dust environment, equivalent to the "high-precision radar" of the sensing component 10. Thanks to this differential design, the measurement system can measure dust particles with different characteristics and dust environments with different fluxes with high precision, avoiding the performance limitations of a single sensor in changing working scenarios. Therefore, the measurement system can not only capture more three-dimensional and accurate data samples, but also has a wider applicability. In this embodiment, the piezoelectric films 5 of the first sensing unit 1001 and the second sensing unit 1002 both adopt the technically mature polyvinylidene fluoride (PVDF) film.

[0074] The signal processing circuit 11 includes two groups of identical and independent signal processing circuits 11. One group of signal processing circuits 11 is connected to the first sensing unit 1001, and the other group of signal processing circuits 11 is connected to the second sensing unit 1002 to process the charge signals output by the two sensing units respectively. AsFigure 11 As shown, the signal processing circuit 11 adopts a four-stage architecture, including: a charge sensitive amplifier 1101, an amplification circuit 1102, a shaping circuit 1103, and a peak holding circuit 1104.

[0075] The charge sensitive amplifier 1101 uses a JFET with high input impedance to process the charge signal from the PVDF film. Through charge induction, the JFET converts the charge signal into a voltage signal. This conversion method avoids the attenuation of the charge signal and ensures signal quality. The amplification circuit 1102 adopts a programmable gain module constructed by an AD620 instrumentation amplifier, and at the same time, a high-pass filter is built in to eliminate the DC offset to amplify the AC signal. The shaping circuit 1103 is a two-stage CR-RC shaping circuit 1103 composed of two operational amplifiers. After receiving the amplified signal from the amplification circuit 1102, it removes high-frequency noise and optimizes the waveform of the signal for subsequent sampling and analysis. The shaped voltage signal enters the peak holding circuit 1104. The peak holding circuit 1104 uses a CLF398 sample and hold chip to achieve a nanosecond-level capture speed, and the holding voltage decay rate is less than 0.1 mV / ms. The peak holding circuit 1104 captures and holds the maximum value of the signal, enabling the signal to remain stable during the sampling process and ensuring that the sampling result will not be distorted due to signal fluctuations.

[0076] The program installed on the host computer 12 includes a communication module, a data sampling module, a data processing module, a data analysis module, and a display and storage module. Through communication with the signal processing circuit 11, the host computer 12 realizes functions such as processing, analyzing the output signal of the sensing component 10, and displaying the results. The program running process of the host computer 12 is as follows:

[0077] S1: After the program starts, the communication module automatically initializes the serial communication parameters and establishes a communication connection with the signal processing circuit 11.

[0078] S2: The data acquisition module starts a data acquisition task according to the preset sampling parameters and receives the signal data from the signal processing circuit 11 in real time.

[0079] S3: The data processing module performs filtering and feature extraction operations on the acquired signal data to extract useful signal feature parameters.

[0080] S4: The data analysis module calculates the momentum of the dust particles using the dust momentum experiment fitting model based on the extracted signal feature parameters, and performs fusion analysis on the measurement data of the two sensing units to obtain the final measurement result.

[0081] S5: The display and storage module displays the measurement result in the form of a chart on the user interface in real time and stores the data in the local database.

[0082] The above are only the preferred specific embodiments of the present invention, which do not limit the patent scope of the present invention. All technical equivalent transformations made by using the content of the specification of the present invention fall within the protection scope of the present invention.

Claims

1. A piezoelectric thin film packaging structure, characterized in that: It includes a housing, a fixing plate, a first electrode layer, a piezoelectric film, a second electrode layer, a bottom plate, a first fastening component and a second fastening component; The first electrode layer and the second electrode layer are respectively arranged on both sides of the piezoelectric film; the fixing plate is arranged on the side of the first electrode layer facing away from the piezoelectric film; the bottom plate is arranged on the side of the second electrode layer facing away from the piezoelectric film; the fixing plate, the first electrode layer, the piezoelectric film, the second electrode layer and the bottom plate are fastened along the thickness direction by a first fastening component, and together constitute a core module; the outer shell is arranged on the side of the fixing plate facing away from the piezoelectric film, and is fastened with the core module along the thickness direction by a second fastening component, and together constitute the packaging structure; The shell extends a wrinkle-removing portion on the side facing the piezoelectric film; the vertical distance from the wrinkle-removing portion to the base plate is less than the thickness of the second electrode layer so as to press the piezoelectric film toward the base plate; the shell also extends a reinforcement portion on the same side of the wrinkle-removing portion, and the reinforcement portion encloses the outer side of the core module.

2. The piezoelectric thin film packaging structure according to claim 1, characterized in that: The wrinkle removal part is made of conductive material; the packaging structure also includes a layer of insulating film; The insulating film is arranged between the first electrode layer and the fixing plate; the insulating film extends toward the geometric center to the inner side of the wrinkle-removing portion to isolate the wrinkle-removing portion from the piezoelectric film.

3. The piezoelectric thin film packaging structure according to claim 1, characterized in that: The first electrode layer is an electrode made of a flexible printed circuit board.

4. The piezoelectric thin film packaging structure according to claim 1, characterized in that: The second electrode layer is an electrode made of a rigid printed circuit board.

5. The piezoelectric thin film packaging structure according to claim 1, characterized in that: It also includes an electrode lead-out member for outputting the charges collected by the first electrode layer and the second electrode layer to the outside; the electrode lead-out member is fixed on a lead-out area extending from the first electrode layer and the second electrode layer.

6. The piezoelectric thin film packaging structure according to claim 1, characterized in that: The wrinkle removal portion is configured in a circular shape.

7. The piezoelectric thin film packaging structure according to claim 1, characterized in that: The shell and the bottom plate are made of aluminum alloy.

8. A piezoelectric thin film packaging process, using the piezoelectric thin film packaging structure according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: stacking the fixing plate, the first electrode layer, the piezoelectric film, the second electrode layer, and the bottom plate in sequence and aligning them with the hole position of the first fastening component; Step 2: Use a first fastening component to pass through the fixing plate, the first electrode layer, the piezoelectric film, the second electrode layer, and the bottom plate in the thickness direction and then fasten them to form the core module; Step 3: placing the shell on the surface of the fixing plate and adjusting the position to align with the hole position of the second fastening assembly; the side of the shell extending with the wrinkle removal part and the reinforcement part faces the fixing plate; Step 4: fastening the housing and the core module along the thickness direction using a second fastening assembly to form the packaging structure; During the fastening process, the pressing state of the wrinkle removal portion against the piezoelectric film is observed and calibrated.

9. Space dust momentum measurement system, characterized by: It comprises a sensor component; the sensor component is equipped with the piezoelectric film packaging structure according to any one of claims 1 to 7.

10. The space dust momentum measurement system according to claim 9, characterized in that: The sensor assembly includes a first sensor unit and a second sensor unit; the first sensor unit and the second sensor unit adopt the packaging structure; The area of ​​the piezoelectric film in the first sensing unit is greater than that of the piezoelectric film in the second sensing unit; and the thickness of the piezoelectric film in the first sensing unit is greater than that of the piezoelectric film in the second sensing unit.

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