Preparation method of DIC nano speckle for heterogeneous material surface

Abstract

The invention provides a preparation method of a DIC nano speckle used on the surface of a heterogeneous material, which comprises the following steps: (1) mixing and dispersing nano particles and a volatile solvent to obtain a nano particle dispersion liquid; (2) preparing a conductive layer on the surface of the cross section of the to-be-detected sample; (3) providing an electrified droplet deposition device which comprises a high-voltage power supply module, a nozzle and a sample table, and the high-voltage power supply module comprises a positive high-voltage power supply module and a negative high-voltage power supply module; placing a to-be-tested sample on a sample table; and (4) connecting the positive high-voltage power supply module with a nozzle, connecting the negative high-voltage power supply module with a sample table, spraying the nano-particle dispersion liquid onto the conductive layer of the sample to be detected, and drying to obtain the DIC nano speckle. The preparation method provided by the invention effectively solves the problem of non-uniform distribution of nano speckles caused by inconsistent adhesion force of nano particles to the surfaces of different materials in the prior art.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of integrated device testing, and relates to a preparation method of DIC nanometer speckle for a surface of a heterogeneous material. BACKGROUND

[0002] In-situ observation and quantitative characterization of microcosmic damage and fracture behavior of a chip are important means for in-depth analysis of failure mechanism. Digital image correlation (DIC) combined with different image shooting means such as optical microscopy (OM), digital microscopy (DM) and scanning electron microscopy (SEM) can be used to in-situ characterize different packaging thermal processes and reliability tests of the chip, so as to obtain microcosmic strain distribution thereof.

[0003] The principle of DIC is that a computer compares images before and after deformation of an object to be measured, finds a relevant area of the images through feature points (speckles), and calculates displacement and strain distribution of the surface of the object to be measured. The quality of the speckles is one of key factors determining the accuracy of DIC technology analysis, and parameters for investigation mainly include high randomness, appropriate speckle size and high contrast. Existing preparation methods that can be used for nanometer speckles mainly include micro-nano etching (focal ion beam or chemical etching), chemical vapor deposition, photolithography, nano-imprinting and metal film reconstruction. These methods are mainly used for metal materials, and the processes are complex and the cost is high, so the above methods are not suitable for preparation of DIC speckles for a section of an integrated device with multiple heterogeneous materials.

[0004] Therefore, a simple and effective preparation method of DIC nanometer speckle for a surface of an integrated device with multiple heterogeneous materials needs to be developed. SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a preparation method of DIC nanometer speckle for a surface of a heterogeneous material. The preparation method provided by the present application disperses nanometer particles into a volatile solvent to form a nanometer particle dispersion liquid, and in a high-voltage device, the nanometer particle dispersion liquid is split into extremely fine atomized particles and forms a stable conical jet state under the action of electrostatic force, surface tension and gravity, and the sprayed nanometer particles are adsorbed on the surface of the sample to which an opposite voltage is applied through electrostatic adsorption, and finally a uniformly dispersed nanometer speckle is formed. After the DIC nanometer speckle is prepared on the surface of the heterogeneous material, it can be used to characterize the local strain distribution of the section.

[0006] To achieve the purpose of the present application, the following technical solutions are adopted:

[0007] In a first aspect, the present application provides a preparation method of DIC nanometer speckle for a surface of a heterogeneous material, which comprises the following steps:

[0008] (1) mixing and dispersing the nanoparticles with a volatile solvent to obtain a nanoparticle dispersion;

[0009] (2) preparing a conductive layer on the cross-section surface of the sample to be tested to obtain the sample to be tested with the conductive layer;

[0010] (3) providing a charged droplet deposition device, wherein the charged droplet deposition device comprises a high-voltage power supply module, a nozzle and a sample stage, and the high-voltage power supply module comprises a positive high-voltage power supply module and a negative high-voltage power supply module;

[0011] placing the sample to be tested with the conductive layer on the sample stage;

[0012] (4) connecting the positive high-voltage power supply module with the nozzle, connecting the negative high-voltage power supply module with the sample stage, spraying the nanoparticle dispersion onto the conductive layer of the sample to be tested, and then drying to obtain the DIC nanoparticle speckle for the surface of heterogeneous materials.

[0013] The preparation method provided by the application uses a high-voltage device (charged droplet deposition device) to uniformly spray the nanoparticle dispersion to the cross-section of a chip containing different heterogeneous materials, realizes the directional deposition of charged droplets, and specifically, the nanoparticle dispersion is split into extremely fine atomized particles and forms a stable conical jet state under the action of electrostatic force, surface tension and gravity, the sprayed nanoparticles are adsorbed on the surface of the conductive layer of the sample to be tested by electrostatic adsorption effect, and the DIC nanoparticle speckle is obtained, thereby effectively solving the problem of uneven distribution of nanoparticle speckles caused by the inconsistent adhesion of nanoparticles to different material surfaces in the prior art.

[0014] The method for preparing the DIC nanoparticle speckle provided by the application can not only significantly improve the uneven dispersion of nanoparticles in heterogeneous materials by relying on electrostatic force, but also reduce the probability of re-aggregation of nanoparticles on the material surface, so that ideal nanoparticle speckles with high contrast, random distribution, consistent size and equal color distribution density are obtained.

[0015] Preferably, the nanoparticles in step (1) comprise any one or a combination of at least two of nano-zirconium dioxide (ZrO2), nano-aluminum trioxide (Al2O3), nano-silicon dioxide (SiO2) and nano-carbon powder.

[0016] Preferably, the average particle size of the nanoparticles in step (1) is 100nm-500nm, such as 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, etc.

[0017] Preferably, the volatile solvent in step (1) comprises any one or a combination of at least two of ethanol (C2H6O), isopropyl alcohol (C3H8O), and acetone (C3H6O).

[0018] Preferably, the ratio of the nanoparticles to the volatile solvent in step (1) is (0.1-0.8 g):(80-200 mL). For example, 0.1-0.8 g can be 0.1 g, 0.2 g, 0.3 g, 0.4 g, 0.5 g, 0.6 g, 0.7 g, 0.8 g, etc., and 80-200 mL can be 80 mL, 90 mL, 100 mL, 110 mL, 120 mL, 130 mL, 140 mL, 150 mL, 160 mL, 170 mL, 180 mL, 190 mL, 200 mL, etc. The ratio of the nanoparticles to the volatile solvent in step (1) is (0.5-0.8 g):(80-100 mL), which means that when the amount of the volatile solvent is 80-100 mL, the amount of the nanoparticles is 0.5-0.8 g.

[0019] Preferably, the dispersion in step (1) is performed by ultrasonic treatment.

[0020] Preferably, the ultrasonic treatment is performed for 5-15 min, for example, 5 min, 7 min, 9 min, 11 min, 13 min, 15 min, etc.

[0021] Preferably, the sample to be tested in step (2) comprises an integrated device containing a heterogeneous material (for example, a chip containing a heterogeneous material, etc.).

[0022] Preferably, the material of the conductive layer in step (2) comprises gold and / or platinum.

[0023] Preferably, the preparation of the conductive layer on the cross-sectional surface of the sample to be tested in step (2) comprises:

[0024] The cross-section of the sample to be tested is polished, and then a conductive layer is prepared on the cross-sectional surface by sputtering.

[0025] Preferably, the sputtering current is 10-40 mA, for example, 10 mA, 15 mA, 20 mA, 25 mA, 30 mA, 35 mA, 40 mA, etc., and the sputtering time is 10-100 s, for example, 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, etc.

[0026] Preferably, the charged droplet deposition device in step (3) further comprises a peristaltic pump and a syringe.

[0027] Preferably, the pump body of the peristaltic pump is selected from 10-30 mL, such as 10 mL, 15 mL, 20 mL, 25 mL, 30 mL, etc., the pump body diameter is 15-25 mm, such as 15 mm, 18 mm, 20 mm, 22 mm, 23 mm, 25 mm, etc., and the pump flow rate is 1-10 mL / h, such as 1 mL / h, 2 mL / h, 3 mL / h, 4 mL / h, 5 mL / h, 8 mL / h, 10 mL / h, etc.

[0028] Preferably, the nozzle in step (3) is connected to a syringe, and the nozzle and the syringe are composed of a screw port needle cylinder, a plastic catheter and a stainless steel flat needle.

[0029] Preferably, the voltage of the positive high-voltage power module in step (4) is set to +5-+30 kV, such as +5 kV, +10 kV, +15 kV, +20 kV, +25 kV, +30 kV, etc.

[0030] Preferably, the voltage of the negative high-voltage power module in step (4) is set to -30--5 kV, such as -30 kV, -25 kV, -20 kV, -15 kV, -10 kV, -5 kV, etc.

[0031] Preferably, the spraying time in step (4) is 1-10 min, such as 1 min, 3 min, 5 min, 8 min, 10 min, etc.

[0032] Preferably, the pump flow rate of the peristaltic pump during spraying in step (4) is 1-10 mL / h, such as 1 mL / h, 2 mL / h, 3 mL / h, 4 mL / h, 5 mL / h, 6 mL / h, 7 mL / h, 8 mL / h, 9 mL / h, 10 mL / h, etc.

[0033] Preferably, the drying in step (4) is carried out in an oven.

[0034] As a preferred technical scheme of the present application, the preparation method comprises the following steps:

[0035] (1) Mix the nanoparticles with the volatile solvent, and ultrasonically treat for 5-15 min to obtain a nanoparticle dispersion liquid;

[0036] (2) Polish the cross section of the sample to be tested, and then prepare a conductive layer on the cross section surface by sputtering to obtain the sample to be tested with the conductive layer;

[0037] The material used for sputtering includes gold and / or platinum, the sputtering current is 10-40 mA, and the sputtering time is 10-100 s;

[0038] (3) provide charged droplet deposition device, the charged droplet deposition device includes high voltage power module, peristaltic pump, syringe and nozzle, sample table, the high voltage power module includes positive high voltage power module and negative high voltage power module, the syringe and nozzle are composed of spiral mouth needle cylinder, plastic conduit and stainless steel flat needle;

[0039] The nanometer particle dispersion liquid is sucked by the syringe, and the sample to be measured with the conductive layer is placed on the sample table.

[0040] (4) connect the positive high voltage power module with the nozzle, connect the negative high voltage power module with the sample table; turn on the total power supply of the charged droplet deposition device, first adjust the flow rate of the peristaltic pump to 5-20 mL / h, after the droplets flow down at the nozzle, change the flow rate of the peristaltic pump to 1-10 mL / h; then turn on the current button of the positive high voltage power module and the negative high voltage power module at the same time, and then turn on the voltage button of the positive high voltage power module and the negative high voltage power module, wherein the voltage of the positive high voltage power module and the negative high voltage power module is set to +5-+30 kV and-30--5 kV respectively, the nanometer particle dispersion liquid is sprayed on the conductive layer of the sample to be measured, after spraying for 1-10 min, the sample to be measured is moved into the oven for drying, and the DIC nanometer speckle for the surface of heterogeneous material is obtained.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] The preparation method provided by the application uniformly sprays the nanometer particle dispersion liquid to the chip section containing different heterogeneous materials by using a high-voltage device (charged droplet deposition device), realizes directional deposition of charged droplets, specifically, the nanometer particle dispersion liquid is split into extremely fine atomized particles and forms a stable conical jet state under the action of electrostatic force, surface tension and gravity through the nozzle, the sprayed nanometer particles are adsorbed on the surface of the conductive layer of the sample to be measured by electrostatic adsorption effect, and the DIC nanometer speckle is obtained, effectively solving the problem of uneven distribution of nanometer speckle caused by inconsistent adhesion of nanometer particles to different material surfaces in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0043] FIG. 1A 、 FIG. 1B 、 FIG. 1C 、 FIG. 1D are the optical microscope test result graphs of the sample to be measured and the nanometer speckle provided by example 1, wherein, FIG. 1A 、 FIG. 1B 、 FIG. 1C 、 FIG. 1D The magnification of 105 times, 211 times, 320 times and 460 times respectively.

[0044] FIG. 2A and FIG. 2B are SEM images of the sample to be tested and nano-speckles provided in Example 1, wherein, FIG. 2A and FIG. 2B have magnifications of 100x, 500x, respectively.

[0045] FIG. 3A , FIG. 3B , FIG. 3C , FIG. 3D are optical microscope test result images of the sample to be tested and nano-speckles provided in Example 2, wherein, FIG. 3A , FIG. 3B , FIG. 3C , FIG. 3D have magnifications of 105x, 211x, 320x, 460x, respectively.

[0046] FIG. 4A and FIG. 4B are SEM images of the sample to be tested and nano-speckles provided in Example 2, wherein, FIG. 4A and FIG. 4B have magnifications of 100x, 500x, respectively.

[0047] FIG. 5A , FIG. 5B , FIG. 5C , FIG. 5D are optical microscope test result images of the sample to be tested and nano-speckles provided in Comparative Example 1, wherein, FIG. 5A , FIG. 5B , FIG. 5C , FIG. 5D have magnifications of 105x, 211x, 320x, 460x, respectively.

[0048] FIG. 6A and FIG. 6B are SEM images of the sample to be tested and nano-speckles provided in Comparative Example 1, wherein, FIG. 6A and FIG. 6B have magnifications of 100x, 500x, respectively.

[0049] FIG. 7A , FIG. 7B , FIG. 7C , FIG. 7D are optical microscope test result images of the sample to be tested and nano-speckles provided in Comparative Example 2, wherein, FIG. 7A , FIG. 7B , FIG. 7C , FIG. 7D have magnifications of 105x, 211x, 320x, 460x, respectively.

[0050] FIG. 8A andFIG. 8B SEM images of the test sample and nanometer speckle provided by Comparative Example 2, wherein, FIG. 8A and FIG. 8B the magnification of which are 100 times, 500 times, respectively.

[0051] FIG. 9A , FIG. 9B , FIG. 9C , FIG. 9D optical microscope test result images of the test sample and nanometer speckle provided by Comparative Example 3, wherein, FIG. 9A , FIG. 9B , FIG. 9C , FIG. 9D the magnification of which are 105 times, 211 times, 320 times, 460 times, respectively.

[0052] FIG. 10A and FIG. 10B SEM images of the test sample and nanometer speckle provided by Comparative Example 3, wherein, FIG. 10A and FIG. 10B the magnification of which are 100 times, 500 times, respectively. DETAILED DESCRIPTION

[0053] The technical solutions of the present application will be further illustrated by specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present application and should not be regarded as specific limitations of the present application.

[0054] Example 1

[0055] In this embodiment, a preparation method of DIC nanometer speckle for the surface of heterogeneous material is provided, which comprises the following steps:

[0056] (1) Preparation of nanoparticle dispersion liquid: 0.2 g of nano-zirconium dioxide (average particle size of 200 nm-400 nm) is dispersed into 160 mL of ethanol, and ultrasonic treatment is performed for 5 min to obtain a nanoparticle dispersion liquid.

[0057] (2) Polishing the cross section of the test sample of the flip chip, and sputtering a conductive layer on the cross section thereof by a gold spraying instrument, wherein the sputtered material is gold, the sputtering current is set to 20 mA, and the sputtering time is set to 20 s to obtain a test sample with a conductive layer.

[0058] (3) Providing a charged droplet deposition device, which comprises a high-voltage power supply module, a peristaltic pump, a syringe and a nozzle, a sample stage, wherein the high-voltage power supply module comprises a positive high-voltage power supply module and a negative high-voltage power supply module, and the syringe and nozzle are composed of a spiral port needle cylinder, a plastic catheter and a stainless steel flat needle.

[0059] The prepared nanoparticle dispersion liquid is sucked by a syringe, a screw needle cylinder, a plastic conduit and a stainless steel flat needle are assembled and fixed on the charged droplet deposition device; the prepared cross-section sample to be tested is placed on the sample table with the cross-section upward, and the sample to be tested is adhered to the sample table.

[0060] (4) The positive high-voltage power module is connected with the nozzle, the negative high-voltage power module is connected with the sample table, the total power supply of the charged droplet deposition device is turned on, the wires are connected, the flow rate of the peristaltic pump is adjusted to 20 mL / h first, after the liquid droplets flow down from the nozzle, the flow rate of the peristaltic pump is changed to 4 mL / h; then the current buttons of the positive and negative power modules are turned on at the same time, and the voltage buttons of the positive and negative power modules are turned on, wherein the voltage of the positive and negative power modules is set to 20 kV and -20 kV respectively, and the current of the positive and negative power modules is set to 0 mA, the nanoparticle dispersion liquid is sprayed on the conductive layer of the sample to be tested, and after spraying for 10 min, the voltage buttons of the positive and negative power modules are turned off at the same time, and then the current buttons of the positive and negative power modules are turned off, and finally the peristaltic pump is turned off.

[0061] (5) The sample to be tested is taken off, the sample to be tested is placed in a dustproof container, the syringe and the nozzle are taken off, the wires are pulled out, and finally the total power supply of the charged droplet deposition device is turned off and the experiment box door is closed.

[0062] (6) The sample to be tested is moved into the oven and placed for 12 h, and the surface of the sample is dried to obtain the DIC nanospeck for the surface of the heterogeneous material.

[0063] Example 2

[0064] The difference between this example and example 1 is only that the nanometer zirconium dioxide in step (1) is replaced by equal mass of nanometer silicon dioxide (average particle size is 500 nm).

[0065] Comparative Example 1

[0066] The difference between this comparative example and example 1 is only that the device for making speck in step (3) is replaced by a spray gun.

[0067] Comparative Example 2

[0068] The difference between this comparative example and example 1 is only that the ethanol in step (1) is replaced by deionized water.

[0069] Comparative Example 3

[0070] The difference between this comparative example and example 1 is only that the nanometer zirconium dioxide in step (1) is replaced by equal mass of micron-sized zirconium dioxide (average particle size is 5 μm).

[0071] The prepared sample to be tested provided by the embodiment 1 of the present application is placed under an optical microscope to observe nanospeck, and the test result is shown in FIG. 1A , FIG. 1B , FIG. 1C , FIG. 1D , wherein the magnification of FIG. 1A , FIG. 1B , FIG. 1C , FIG. 1D is 105 times, 211 times, 320 times and 460 times respectively.

[0072] The prepared sample to be tested provided by the embodiment 1 of the present application is placed under a scanning electron microscope (SEM) to observe nanospeck, and the test result is shown in FIG. 2A and FIG. 2B , wherein the magnification of FIG. 2A and FIG. 2B is 100 times and 500 times respectively.

[0073] The prepared sample to be tested provided by the embodiment 2 of the present application is placed under an optical microscope to observe nanospeck, and the test result is shown in FIG. 3A , FIG. 3B , FIG. 3C , FIG. 3D , wherein the magnification of FIG. 3A , FIG. 3B , FIG. 3C , FIG. 3D is 105 times, 211 times, 320 times and 460 times respectively.

[0074] The prepared sample to be tested provided by the embodiment 2 of the present application is placed under a scanning electron microscope (SEM) to observe nanospeck, and the test result is shown in FIG. 4A and FIG. 4B , wherein the magnification of FIG. 4A and FIG. 4B is 100 times and 500 times respectively.

[0075] The prepared sample to be tested provided by the comparative example 1 of the present application is placed under an optical microscope to observe nanospeck, and the test result is shown in FIG. 5A , FIG. 5B , FIG. 5C , FIG. 5D , wherein the magnification of FIG. 5A , FIG. 5B , FIG. 5C , FIG. 5D is 105 times, 211 times, 320 times and 460 times respectively.

[0076] The prepared sample to be tested provided by the comparative example 1 of the present application is placed under a scanning electron microscope (SEM) to observe nanospeck, and the test result is shown in FIG. 6Aand FIG. 6B As shown in FIGS. FIG. 6A and FIG. 6B The magnification of FIGS.

[0077] The prepared sample provided by the present application comparative example 2 was placed under an optical microscope to observe the nanospeck, and the test results are shown in FIG. 7A , FIG. 7B , FIG. 7C , FIG. 7D As shown in FIGS. FIG. 7A , FIG. 7B , FIG. 7C , FIG. 7D The magnification of FIGS.

[0078] The prepared sample provided by the present application comparative example 2 was placed under a scanning electron microscope (SEM) to observe the nanospeck, and the test results are shown in FIG. 8A and FIG. 8B As shown in FIGS. FIG. 8A and FIG. 8B The magnification of FIGS.

[0079] The prepared sample provided by the present application comparative example 3 was placed under an optical microscope to observe the nanospeck, and the test results are shown in FIG. 9A , FIG. 9B , FIG. 9C , FIG. 9D As shown in FIGS. FIG. 9A , FIG. 9B , FIG. 9C , FIG. 9D The magnification of FIGS.

[0080] The prepared sample provided by the present application comparative example 3 was placed under a scanning electron microscope (SEM) to observe the nanospeck, and the test results are shown in FIG. 10A and FIG. 10B As shown in FIGS. FIG. 10A and FIG. 10B The magnification of FIGS.

[0081] As can be seen from FIGS. 1, 2, 3 and 4, the nanospeck prepared by the preparation method provided by the present application is an ideal nanospeck with high contrast, random distribution, consistent size and equal color distribution density. The present application effectively solves the problem of uneven distribution of nanospeck caused by inconsistent adhesion of nanospeck to different material surfaces in the prior art.

[0082] As can be seen from FIGS. 5 and 6, the nano-speckles prepared by the preparation method provided in Comparative Example 1 have slight coffee rings and uneven speckle distribution; as can be seen from FIGS. 7 and 8, the nano-speckles prepared by the preparation method provided in Comparative Example 2 have very serious coffee rings and extremely uneven speckle particle distribution; as can be seen from FIGS. 9 and 10, the nano-speckles prepared by the preparation method provided in Comparative Example 3 have too large distribution density and serious agglomeration, and there may be a problem of insufficient contrast, which is not conducive to subsequent speckle analysis.

[0083] The applicant declares that the DIC nano-speckle preparation method for the surface of a heterogeneous material of the present application is illustrated by the above examples, but the present application is not limited to the above examples, i.e. it does not mean that the present application must rely on the above examples to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the raw materials selected by the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for the preparation of DIC nanospeck for heterogeneous material surfaces, characterized by, The preparation method comprises the following steps: (1) mixing nanoparticles with a volatile solvent, dispersing to obtain a nanoparticle dispersion liquid; (2) preparing a conductive layer on the cross-section surface of the sample to be tested to obtain the sample to be tested with the conductive layer; (3) providing a charged droplet deposition device, wherein the charged droplet deposition device comprises a high-voltage power supply module, a nozzle and a sample stage, and the high-voltage power supply module comprises a positive high-voltage power supply module and a negative high-voltage power supply module; placing the sample to be tested with the conductive layer on the sample stage; (4) connecting the positive high-voltage power supply module with the nozzle, connecting the negative high-voltage power supply module with the sample stage, spraying the nanoparticle dispersion liquid onto the conductive layer of the sample to be tested, and then drying to obtain the DIC nanospeck for the surface of heterogeneous materials.

2. The production method according to claim 1, characterized by, The nanoparticles in step (1) comprise any one or a combination of at least two of nano-zirconium dioxide, nano-aluminum oxide, nano-silicon dioxide and nano-carbon powder. Preferably, the average particle size of the nanoparticles in step (1) is 100-500 nm.

3. The production method according to claim 1 or 2, characterized by, The volatile solvent in step (1) comprises any one or a combination of at least two of ethanol, isopropyl alcohol and acetone. Preferably, the use ratio of the nanoparticles to the volatile solvent in step (1) is (0.1-0.8 g):(80-200 mL).

4. The production method according to any one of claims 1 to 3, characterized by, The sample to be tested in step (2) comprises an integrated device containing heterogeneous materials. Preferably, the material of the conductive layer in step (2) comprises gold and / or platinum.

5. The production method according to any one of claims 1 to 4, characterized by, The preparation of the conductive layer on the cross-section surface of the sample to be tested in step (2) specifically comprises: polishing the cross-section of the sample to be tested, and then preparing the conductive layer on the cross-section surface by sputtering; Preferably, the current of the sputtering is 10-40 mA, and the sputtering time is 10-100 s.

6. The production method according to any one of claims 1 to 5, characterized by, The charged droplet deposition device in step (3) further comprises a peristaltic pump and a syringe. Preferably, the pump body of the peristaltic pump is selected to be 10-30 mL, the pump body diameter is 15-25 mm, and the pump flow rate is 1-10 mL / h. Preferably, the nozzle in step (3) is connected with the syringe, and the nozzle and the syringe are composed of a screw port needle cylinder, a plastic catheter and a stainless steel flat needle.

7. The production method according to any one of claims 1 to 6, characterized by, The voltage of the positive high-voltage power supply module in step (4) is set to +5-+30 kV.

8. The production method according to any one of claims 1 to 7, characterized by, The voltage of the negative high-voltage power supply module in step (4) is set to -30--5 kV.

9. The production method according to any one of claims 1 to 8, characterized by, The spraying time in step (4) is 1-10 min. Preferably, the pump flow rate of the peristaltic pump during the spraying in step (4) is 1-10 mL / h. Preferably, the drying in step (4) is performed in an oven.

10. A process according to any one of claims 1 to 9, wherein the process is carried out at a temperature of from 20 to 100°C. The preparation method comprises the following steps: (1) mixing nanoparticles with a volatile solvent, ultrasonic treatment for 5-15 min to obtain a nanoparticle dispersion liquid; (2) polishing the cross-section of the sample to be tested, and then preparing a conductive layer on the cross-section surface by sputtering to obtain the sample to be tested with the conductive layer; wherein the material for sputtering comprises gold and / or platinum, the current of the sputtering is 10-40 mA, and the sputtering time is 10-100 s; (3) A charged droplet deposition device is provided, which comprises a high-voltage power module, a peristaltic pump, a syringe and a nozzle, a sample stage, wherein the high-voltage power module comprises a positive high-voltage power module and a negative high-voltage power module, and the syringe and the nozzle are composed of a spiral port needle cylinder, a plastic catheter and a stainless steel flat needle; The nanometer particle dispersion liquid is sucked by the syringe, and the sample to be tested with the conductive layer is placed on the sample stage; (4) The positive high-voltage power module is connected with the nozzle, and the negative high-voltage power module is connected with the sample stage; the total power supply of the charged droplet deposition device is turned on, the flow rate of the peristaltic pump is first adjusted to 5-20 mL / h, then the flow rate of the peristaltic pump is changed to 1-10 mL / h after the droplets flow down from the nozzle; then the current buttons of the positive high-voltage power module and the negative high-voltage power module are turned on at the same time, and then the voltage buttons of the positive high-voltage power module and the negative high-voltage power module are turned on, wherein the voltage of the positive high-voltage power module and the negative high-voltage power module is set to +5-+30 kV and -30--5 kV respectively, the nanometer particle dispersion liquid is sprayed on the conductive layer of the sample to be tested, and after spraying for 1-10 min, the sample to be tested is moved into an oven for drying, thereby obtaining the DIC nanometer speckle for the surface of a heterogeneous material.

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