A method for local polarization of a high-precision flexible piezoelectric thin film material

Abstract

The present invention discloses a method for local polarization of a high-precision flexible piezoelectric thin film material. First, a local polarization process is adopted, and a flat-headed circular indenter is used as the upper and lower electrode polarization indenter to press against the thin film. The thin film is divided into surfaces A and B, which are respectively contacted with the positive and negative electrodes. With 500V as the initial voltage, the voltage is increased in a gradient of 500V, and loading is carried out at each gradient voltage until the voltage rises to 5000V. Then, a circular ring structure indenter is prepared to eliminate the outer halo polarization region at the edge: the surfaces A and B of the thin film are respectively contacted with the positive and negative electrodes, and loading is carried out starting from a voltage of 500V until the voltage increases to 2000V, and the piezoelectric D 33 value of the outer halo region at the edge is detected until the D 33 value of the edge region drops to 0. The PVDF thin film polarized by the method of the present invention can accurately control the polarization region. Moreover, the present invention adopts alternating polarization of positive and negative voltages, with a high polarization piezoelectric coefficient and good polarization stability.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor materials, and in particular relates to a local polarization method for piezoelectric film materials. Background Art

[0002] In sensor technology, the existing piezoelectric film local polarization process can use a circular indenter to directly polarize the target area. The polarization diagram is shown in Figure 1 The use of DC polarization will lead to a halo in the polarization area: that is, the target polarization area obtains better piezoelectric performance (piezoelectric coefficient D 33 ), but the outside of the target polarization area is also polarized, which will cause D 33 The value slowly decreases to 0, such as Figure 2 As shown, the polarization halo area is too large, which seriously affects the piezoelectric performance test results of the film.

[0003] AC polarization can reduce this polarization halo to a certain extent, but the polarization effect of AC polarization is related to the AC voltage frequency. It is necessary to strictly control multiple parameters such as AC polarization field strength, electric field frequency, and voltage loading time. And because AC polarization is relative to positive and negative voltages, the positive voltage loading time is short, resulting in low piezoelectric performance in the final target polarization area. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a high-precision flexible piezoelectric film material local polarization method, firstly adopting a local polarization process, using a flat circular pressure head as an upper and lower electrode polarization pressure head to press the film; the film is divided into A and B surfaces, which are respectively in contact with positive and negative electrodes, with 500V as the initial voltage, and then with 500V as the gradient voltage, and loading is performed on each gradient voltage until the voltage rises to 5000V; then a circular ring structure pressure head is prepared to eliminate the edge halo polarization area: the A and B surfaces of the film are respectively in contact with the positive and negative electrodes, and a voltage of 500V is used as the starting voltage for loading until the voltage increases to 2000V, and the piezoelectric D in the edge halo area is detected at the same time. 33 value, until the edge area D 33 The value drops to 0. The PVDF film obtained by polarizing the method of the present invention can accurately control the polarization area. In addition, the present invention adopts positive and negative voltage alternating polarization, has a high polarization piezoelectric coefficient, and has good polarization stability.

[0005] The technical solution adopted by the present invention to solve the technical problem includes the following steps:

[0006] Step 1: Using a local polarization process, a flat circular indenter is used as the upper and lower electrode polarization indenters to press the film;

[0007] Step 2: Divide the film into side A and side B. First, let side A contact the positive electrode and side B contact the negative electrode, and apply a voltage of 500V for T1 minutes.

[0008] Step 3: Reverse the film, let side B contact the positive electrode and side A contact the negative electrode, and apply a voltage of 500V for T1 minutes.

[0009] Step 4: Then reverse the film again, let side A contact the positive electrode and side B contact the negative electrode; increase the voltage in a gradient of 500V, and apply for T2 minutes after each voltage increase until the voltage reaches 5000V and then apply for T2 minutes to end the polarization process.

[0010] Step 5: Eliminate the polarization region of the outer halo at the edge.

[0011] Step 5-1: Prepare a circular ring structure indenter and align it with the outer halo region of polarization.

[0012] Step 5-2: Let side B of the film contact the positive electrode and side A contact the negative electrode, apply a voltage of 500V for a preset time, and simultaneously detect the piezoelectric D 33 value at the outer halo region of the edge.

[0013] Step 5-3: Increase the voltage in a gradient of 500V, and apply for a preset time after each voltage increase until the voltage increases to 2000V, and simultaneously detect the piezoelectric D 33 value at the outer halo region of the edge.

[0014] Step 5-4: Maintain the voltage at 2000V until the D value in the edge region 33 drops to 0.

[0015] Preferably, T1 = 2 and T2 = 1.

[0016] The beneficial effects of the present invention are as follows:

[0017] 1. The PVDF film polarized by the method of the present invention can accurately control the polarization region.

[0018] 2. The present invention uses alternating polarization of positive and negative voltages, with a high polarization piezoelectric coefficient and good polarization stability.

[0019] 3. The alternating polarization method of positive and negative voltages proposed by the present invention provides a new polarization method for the polarization of flexible piezoelectric films. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the prior art polarization method.

[0021] Figure 2 It is a schematic diagram of the corresponding relationship between D33 of the film after polarization in the prior art and the position.

[0022] Figure 3Schematic diagram of the polarization method of the method of the present invention.

[0023] Figure 4 Schematic diagram of the corresponding relationship between D33 of the film after polarization and the position of the method of the present invention. Detailed implementation manners

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] The present invention adopts a local polarization process and applies a gradient DC voltage to the target polarization region.

[0026] A local polarization method for a high-precision flexible piezoelectric thin film material includes the following steps:

[0027] Step 1: Adopt a local polarization process, use a flat-head circular indenter as the upper and lower electrode polarization indenters, and press on the thin film; the indenter presses on the thin film by its own gravity without applying additional external force;

[0028] Step 2: Divide the thin film into A and B sides. First, the A side contacts the positive electrode and the B side contacts the negative electrode, and load with an initial voltage of 500V for 2 minutes;

[0029] Step 3: Reverse the thin film, the B side contacts the positive electrode, the A side contacts the negative electrode, and load with a voltage of 500V for 2 minutes; during the process of alternating positive and negative voltage loading, the dipoles in the thin film flip. The unstable polarization terms in the thin film are eliminated.

[0030] Step 4: Then reverse the thin film again, the A side contacts the positive electrode, the B side contacts the negative electrode; increase the voltage in a gradient of 500V, and load for 1 minute after each voltage increase until the voltage rises to 5000V and then load for 1 minute to end the polarization process;

[0031] Step 5: Eliminate the edge outer halo polarization region;

[0032] Step 5-1: Prepare a circular ring-shaped indenter and align it with the polarization outer halo region;

[0033] Step 5-2: The B side of the thin film contacts the positive electrode, the A side contacts the negative electrode, load with a voltage of 500V for a preset time, and simultaneously detect the piezoelectric D 33 value;

[0034] Step 5-3: Increase the voltage in a gradient of 500V, and load for a preset time after each voltage increase until the voltage increases to 2000V, and simultaneously detect the piezoelectric D 33 value;

[0035] Step 5-4: Maintain the voltage at 2000V until the D value of the edge region drops to 0. 33 value drops to 0.

[0036] AppendixFigure 3 Schematic diagram of the film after polarization treatment using the method of the present invention Figure 4 Schematic diagram of the correspondence between D33 of the film and the position after polarization by the method of the present invention. It can be seen from the figure that after polarization treatment using the method of the present invention, the circular target area of the film reaches D 33 The polarization expected value and is uniform. At the same time, the polarization outer halo area at the edge of the film is eliminated, and the D 33 value drops to 0.

Claims

1. A method for local polarization of a high-precision flexible piezoelectric thin film material, characterized in that, The method includes the following steps: Step 1: Adopt the local polarization process. Use a flat-head circular indenter as the upper and lower electrode polarization indenters to press and contact the film; Step 2: Divide the film into side A and side B. First, make side A contact the positive electrode and side B contact the negative electrode, and apply an initial voltage of 500V for T1 minutes; Step 3: Reverse the film, make side B contact the positive electrode and side A contact the negative electrode, and apply a voltage of 500V for T1 minutes; Step 4: Then reverse the film again, make side A contact the positive electrode and side B contact the negative electrode; increase the voltage in a gradient of 500V, and apply for T2 minutes after each voltage increase until the voltage reaches 5000V and then apply for T2 minutes to end the polarization process; Step 5: Eliminate the edge outer halo polarization region; Step 5-1: Prepare a circular-ring structure indenter and align it with the polarization outer halo region; Step 5-2: Make the B side of the thin film contact the positive electrode and the A side contact the negative electrode, apply a voltage of 500 V for a preset time, and simultaneously detect the piezoelectric D 33 value; Step 5-3: Increase the voltage in a gradient of 500V, and load the preset time after each voltage boost until the voltage increases to 2000V. At the same time, detect the piezoelectric D value in the outer halo region at the edge. 33 value; Step 5-4: Maintain at 2000V until the 33 value drops to 0 in the edge region D. 33 value drops to 0.

2. The local polarization method of a high-precision flexible piezoelectric thin film material according to claim 1, wherein T1 = 2 and T2 = 1.

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