Single-face lead-out high-precision piezoelectric film sensor

Abstract

The utility model provides a single-side lead-out high-precision piezoelectric film sensor. The single-side lead-out high-precision piezoelectric film sensor comprises an upper packaging layer, an upper electrode, a functional layer, a lower electrode and a lower packaging layer, the functional layer comprises a sensitive area and an auxiliary area; the upper electrode is tightly attached to the upper surface of the functional layer and comprises an upper effective electrode overlapped with the sensitive area, an upper extraction electrode communicated with the upper effective electrode and an upper independent electrode spaced from the upper effective electrode; the lower electrode is tightly attached to the lower surface of the functional layer and comprises a lower effective electrode coinciding with the sensitive area, a lower extraction electrode communicated with the lower effective electrode and a lower independent electrode, and a distance is formed between the lower independent electrode and the lower effective electrode. According to the utility model, the piezoelectric film and the electrode are partitioned, so that only the charge output by the sensitive area is calculated during calibration, the attachment area of the extraction electrode and the independent electrode on the auxiliary area is reduced, the charge output of the auxiliary area is further reduced, and the measurement result is more accurate.

Description

Technical Field

[0001] The utility model relates to the technical field of piezoelectric films, in particular to a high-precision piezoelectric film sensor with single-side lead-out. Background Art

[0002] Piezoelectric film materials exhibit the same piezoelectric effect as piezoelectric ceramics and other piezoelectric materials. Specifically, when physical pressure is applied to a piezoelectric material, the electric dipole moment within the material shortens due to compression. To counteract this change, the piezoelectric material generates equal amounts of positive and negative charges on opposite surfaces. By measuring the charge generated by the piezoelectric material under load, it is possible to convert the charge into the applied force. Therefore, piezoelectric materials are often used as sensors, and piezoelectric film is no exception.

[0003] Due to the low Curie temperature of piezoelectric film, the upper and lower electrodes cannot be connected by conventional high-temperature welding process. The existing technology adopts a stacking process. On the organic polymer substrate, the lower electrode and electrode lead are first printed with silver paste, and then the piezoelectric film is prepared on the lower electrode. Finally, the upper electrode is printed with silver paste. At the same time, the upper electrode is connected to the previous electrode lead by jumping steps, so that the upper and lower electrodes are connected through a single side. However, under normal circumstances, the thickness of the piezoelectric film is often greater than the thickness of the electrode. As a result, when the upper electrode printed with silver paste is connected to the previous electrode lead by jumping steps, the silver paste electrode is easily broken at the edge of the piezoelectric film because the silver paste thickness is less than the piezoelectric film thickness. Although the silver paste has a certain fluidity, the difference between its thickness and the thickness of the piezoelectric film is too large, resulting in insufficient silver paste to fill the gap at the edge of the piezoelectric film, and there is a risk of short circuit.

[0004] In the actual use of piezoelectric film sensors, it is generally necessary to calibrate the piezoelectric film sensor first. The calibration refers to determining the corresponding relationship between the output charge of the piezoelectric film and other physical parameters, where the physical parameters refer to stress, strain, pressure, etc.; the piezoelectric film sensor that has established a certain force-electric relationship through calibration can be used to quantitatively analyze the numerical value of the loading force. The specific calibration method is to determine a portion of the loading area on the surface of the piezoelectric film sensor, which corresponds to the sensitive area of ​​the piezoelectric film; then the force is evenly loaded on the sensitive area, and the deformation of the sensitive area generates charge. The charge is then extracted through the effective electrodes attached to the upper and lower surfaces of the sensitive area. The charge is then transmitted to the electrode pins through the lead-out electrodes attached to the auxiliary area, and then transmitted to the external detection equipment through the electrode pin connecting wires. The sensor output charge at this time is recorded, thus obtaining a set of corresponding relationships between the loading force and the charge of the sensor. The loading force is continuously changed, and the output charge corresponding to the loading force is recorded multiple times. By processing the recorded data, the relationship between the loading force and the output charge on this sensitive area of ​​the sensor is obtained: Q = KF. The force-electric relationship of the sensor per unit area of ​​the sensitive area can be expressed by the following formula:

[0005]

[0006] Since the sensitive area S is a constant, the above formula can be transformed into:

[0007]

[0008] The above formula indicates that under a certain loading force, the amount of charge that can be output per unit area of ​​the sensitive area of ​​the piezoelectric film sensor is proportional to the magnitude of the loading force. At the same time, it can be seen from the above calibration method that the total amount of charge output by the piezoelectric film sensor is not only related to the loading force, but also to the area of ​​the piezoelectric film on the piezoelectric film sensor that can output charge. However, existing piezoelectric film sensors do not distinguish between piezoelectric films. The electrode lead wires prepared at the same time as the upper and lower electrodes are also attached to the surface of the piezoelectric film. When the piezoelectric film at the lead wire position is affected by the loading force, it will also generate charge. This part of the charge will be transmitted to the external collection device together with the charge output by the upper and lower electrodes, and will eventually be fed back into the measurement results. The result of this measurement is that the amount of charge collected has increased, but when calculating the area generating the charge, the loading area only calculates the area of ​​the upper and lower electrodes, and does not include the area of ​​the lead wire part, resulting in errors in the final measurement result and inaccuracy.

[0009] For example, utility model patent CN 113497177 B proposes a flexible vibration sensor based on PVDF film. In this utility model, the short side of the L-shaped electrode is attached to the PVDF film and is considered the effective electrode, and the covered piezoelectric film is the sensitive area. The long side of the electrode is used to transmit charge and is the extraction electrode. In actual use, the part where the long side of the L-shaped electrode contacts the PVDF film will also output charge, which is included in the total charge Q. In subsequent calculations, the increase in charge Q will be attributed to the increase in the applied loading force. However, in fact, the increase in charge Q is due to the increase in the area of ​​the output charge. Utility Model Content

[0010] The purpose of the utility model is to provide a high-precision piezoelectric film sensor with single-side lead-out to solve the above-mentioned deficiencies in the prior art.

[0011] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0012] A single-sided lead-out high-precision piezoelectric film sensor, characterized in that it includes an upper packaging layer, an upper electrode, a functional layer, a lower electrode, and a lower packaging layer stacked in sequence from top to bottom; the functional layer includes a sensitive area and an auxiliary area; the sensitive area is the area on the functional layer corresponding to the calibration area, and the auxiliary area is all areas on the functional layer except the sensitive area; the upper electrode is tightly attached to the upper surface of the functional layer, including an upper effective electrode overlapping with the sensitive area, an upper lead-out electrode connected to the upper effective electrode, and an upper independent electrode with a spacing from the upper effective electrode; the lower electrode is tightly attached to the lower surface of the functional layer, including a lower effective electrode overlapping with the sensitive area, a lower lead-out electrode connected to the lower effective electrode, and a lower independent electrode with a spacing from the lower effective electrode.

[0013] Furthermore, the functional layer is made of a piezoelectric polymer film, a piezoelectric ceramic film or a piezoelectric single crystal film.

[0014] Furthermore, in addition to the effective electrode, the sum of the areas of other electrode structures attached to the auxiliary region of the functional layer of the upper electrode and the lower electrode does not exceed 100% of the effective electrode area; the shapes of the upper lead-out electrode and the lower lead-out electrode are not limited; the spacing between the upper independent electrode and the upper effective electrode and the spacing between the lower independent electrode and the lower effective electrode are not less than 1nm.

[0015] Furthermore, the lower lead-out electrode is provided with a first potential point, the lower independent electrode is provided with a second potential point, the upper lead-out electrode is provided with a third potential point, and the upper independent electrode is provided with a fourth potential point; the first potential point and the fourth potential point, the second potential point and the third potential point form a path through a conductor or conductive material.

[0016] Furthermore, at least one through hole is provided on the auxiliary area of ​​the functional layer, and the through hole is filled with the conductor or conductive material. The first potential point and the fourth potential point, the second potential point and the third potential point can be connected through the conductor or conductive material in the through hole to form a path.

[0017] Furthermore, the first potential point and the fourth potential point, and the second potential point and the third potential point can be connected from the outer side of the functional layer through a climbing structure made of a conductor or a conductive material to form a path.

[0018] Furthermore, the upper packaging layer and the lower packaging layer are thin-layer insulators made of polyimide or FEP fluorinated ethylene propylene.

[0019] It can be seen from the above technical solutions that the present invention has the following advantages compared with the prior art:

[0020] 1. This utility model divides the piezoelectric film functional layer into a sensitive area and an auxiliary area. It is clarified that only the charge output from the sensitive area is calculated during calibration. Correspondingly, only the charge output from the sensitive area is calculated during use. This fully corresponds the calibration and use of the piezoelectric film sensor, making the measurement results more accurate.

[0021] 2. This invention reduces the area of ​​conductive material attached to the auxiliary region of the functional layer, thereby reducing the amount of charge output by regions other than the sensitive region. This allows the load calculated from the charge to be closer to the load-charge relationship used during calibration, resulting in more accurate measurement results.

[0022] 3. The utility model uses a through-hole filled with conductive material or a climbing structure made of conductive material to enable the lead electrodes of the upper and lower electrodes to form a path with the independent electrode on the other side respectively, so as to realize the output of the electrical signal on the lower surface of the functional layer to the electrical signal on the upper surface, and solve the problem that the silver paste printing is prone to breakage when connected to the electrode lead wire by jumping steps. On the one hand, it improves the reliability of the electrical connection, and on the other hand, it also reduces the overall thickness of the piezoelectric film sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the overall structure of the piezoelectric film sensor of the present invention;

[0024] Figure 2 This is a schematic diagram of the through-hole structure on the auxiliary area of ​​the utility model;

[0025] Figure 3 is a schematic diagram of the climbing structure of the utility model;

[0026] In the figure: 1. Upper packaging layer; 2. Upper electrode; 21. Upper effective electrode; 22. Upper lead electrode; 23. Upper independent electrode; 3. Functional layer; 4. Lower electrode; 41. Lower effective electrode; 42. Lower lead electrode; 43. Lower independent electrode; 5. Lower packaging layer; 6. Through hole; 7. Climbing structure. DETAILED DESCRIPTION

[0027] A preferred embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0028] like Figure 1 The single-sided high-precision piezoelectric film sensor is characterized in that it includes an upper packaging layer 1, an upper electrode 2, a functional layer 3, a lower electrode 4, and a lower packaging layer 5 stacked in sequence from top to bottom; the functional layer 3 includes a sensitive area 31 and an auxiliary area 32; the sensitive area 31 is the area on the functional layer 3 corresponding to the calibration area, and the auxiliary area 32 is all areas on the functional layer 3 except the sensitive area 31; correspondingly, when in use, only the charge output by the sensitive area 31 is calculated, and the calibration and use of the piezoelectric film sensor are completely consistent, so that the measurement results are more accurate.

[0029] Specifically, the upper electrode 2 is tightly attached to the upper surface of the functional layer 3, including an upper effective electrode 21 overlapping with the sensitive area 31, an upper lead-out electrode 22 connected to the upper effective electrode 21, and an upper independent electrode 23 spaced apart from the upper effective electrode 21; the lower electrode 4 is tightly attached to the lower surface of the functional layer, including a lower effective electrode 41 overlapping with the sensitive area 21, a lower lead-out electrode 42 connected to the lower effective electrode, and a lower independent electrode 43 spaced apart from the lower effective electrode 41.

[0030] In specific use, the functional layer 3 is made of piezoelectric polymer film, piezoelectric ceramic film or piezoelectric single crystal film; the sum of the areas of other electrode structures attached to the auxiliary region 32 of the functional layer 3 of the upper electrode 2 and the lower electrode 3, in addition to the effective electrode, does not exceed 100% of the effective electrode area. By reducing the attachment area of ​​the conductive material on the auxiliary region 32 of the functional layer 3, the charge output from other areas of the functional layer 3 except the sensitive region 31 is reduced, so that when the sensor is actually used, the load converted from the charge is closer to the load-charge relationship during calibration, thereby making the measurement result more accurate; the shape of the upper extraction electrode 22 and the lower extraction electrode 23 is not limited, and can be in the form of a uniform width from the head close to the effective electrode to the tail away from the effective electrode, or in the form of a tail enlarged to accommodate an external circuit, or in the form of a head smaller than the tail; the spacing between the upper independent electrode 23 and the upper effective electrode 21 and the spacing between the lower independent electrode 43 and the lower effective electrode 41 are not less than 1nm.

[0031] In specific use, the lower lead-out electrode 42 is provided with a first potential point, the lower independent electrode 43 is provided with a second potential point, the upper lead-out electrode 22 is provided with a third potential point, and the upper independent electrode 23 is provided with a fourth potential point; the first potential point and the fourth potential point, the second potential point and the third potential point form a path through a conductor or conductive material.

[0032] Specifically, such as Figure 2 and 3 As shown, in order to improve the reliability of electrical connection, in this preferred embodiment, the first potential point and the fourth potential point, the second potential point and the third potential point form a path through the following two methods: two through holes 6 can be set on the auxiliary area of ​​the functional layer, and the through holes are filled with the conductor or conductive material. The first potential point and the fourth potential point, the second potential point and the third potential point are connected through the conductor or conductive material in the through holes 6 to form a path. The through holes 6 can be prepared by laser positioning and drilling. The first potential point and the fourth potential point, the second potential point and the third potential point can also be connected from the outer side of the functional layer through a climbing structure 7 made of a conductor or conductive material, such as copper tape, to form a path. In specific use, the first potential point and the fourth potential point, the second potential point and the third potential point are generally connected in the above-mentioned way to form a path, which can effectively improve the accuracy of the piezoelectric film sensor while ensuring the single-sided lead-out effect.

[0033] The upper packaging layer and the lower packaging layer described in this preferred embodiment are thin-layer insulators made of polyimide or FEP (fluorinated ethylene propylene).

[0034] Furthermore, the relationship between sensor load and output charge was tested by using different impact forces generated by free-falling rods from different heights. Table 1 shows the data recorded when a rod with a diameter of 10mm was impacted by rod 1, Table 2 shows the data recorded when a rod with a diameter of 15mm was impacted by rod 2 with a 2mm lead-out electrode width, and Table 3 shows the data recorded when a rod with a diameter of 0.8mm was impacted by rod 2.

[0035]

[0036] Table 1

[0037]

[0038] Table 2

[0039]

[0040] Table 3

[0041] According to the data in the table, the output of the charge at the lead position on the auxiliary area can affect the charge output per unit area by more than 30%. The piezoelectric film sensor structure obtained by the utility model greatly reduces the electrode coverage area on the auxiliary area. Even if the load is loaded to the lead position on the auxiliary area, the amount of charge output at the lead position is very small, and the impact on the charge output per unit area is reduced to within 5%, with high precision.

[0042] The above-described embodiments are merely descriptions of preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A high-precision piezoelectric film sensor with single-sided lead-out, characterized in that: It includes an upper packaging layer, an upper electrode, a functional layer, a lower electrode, and a lower packaging layer stacked in sequence from top to bottom; The functional layer includes a sensitive area and an auxiliary area; the sensitive area is the area on the functional layer that is included in the calibration area, and the auxiliary area is all areas on the functional layer except the sensitive area; The upper electrode is closely attached to the upper surface of the functional layer, including an upper effective electrode overlapping with the sensitive area, an upper lead-out electrode connected to the upper effective electrode, and an upper independent electrode spaced apart from the upper effective electrode; The lower electrode is tightly attached to the lower surface of the functional layer, and includes a lower effective electrode overlapping the sensitive area, a lower lead-out electrode communicating with the lower effective electrode, and a lower independent electrode spaced apart from the lower effective electrode.

2. The high-precision piezoelectric film sensor with single-side lead-out according to claim 1, characterized in that: The functional layer is made of piezoelectric polymer film, piezoelectric ceramic film or piezoelectric single crystal film.

3. The high-precision piezoelectric film sensor with single-side lead-out according to claim 1, characterized in that: The sum of the areas of other electrode structures attached to the auxiliary region of the functional layer of the upper and lower electrodes, except for the effective electrodes, does not exceed 100% of the area of ​​the effective electrodes; the shapes of the upper lead-out electrode and the lower lead-out electrode are not limited; the spacing between the upper independent electrode and the upper effective electrode and the spacing between the lower independent electrode and the lower effective electrode are not less than 1 nm.

4. The high-precision piezoelectric film sensor with single-side lead-out according to claim 3, characterized in that: The lower lead-out electrode is provided with a first potential point, the lower independent electrode is provided with a second potential point, the upper lead-out electrode is provided with a third potential point, and the upper independent electrode is provided with a fourth potential point; the first potential point and the fourth potential point, the second potential point and the third potential point form a path through a conductor or conductive material.

5. The high-precision piezoelectric film sensor with single-side lead-out according to claim 4, characterized in that: At least one through hole is provided on the auxiliary area of ​​the functional layer, and the conductor or conductive material is filled in the through hole. The first potential point and the fourth potential point, the second potential point and the third potential point can be connected through the conductor or conductive material in the through hole to form a path.

6. The high-precision piezoelectric film sensor with single-side lead-out according to claim 4, characterized in that: The first potential point and the fourth potential point, and the second potential point and the third potential point can be connected from the outer side of the functional layer through a climbing structure made of a conductor or a conductive material to form a path.

7. The high-precision piezoelectric film sensor with single-side lead-out according to claim 1, characterized in that: The upper packaging layer and the lower packaging layer are thin-layer insulators made of polyimide or FEP fluorinated ethylene propylene.

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