A device for preparing array-type ACF adhesive film based on electrostatic adsorption and a preparation method thereof

Abstract

The application belongs to the technical field of anisotropic conductive adhesive film, and relates to a device for preparing an array type ACF adhesive film based on electrostatic adsorption and a preparation method thereof. The device comprises an electrostatic adsorption roller, an electrostatic eliminator and an electrostatic generator. The electrostatic adsorption roller is a hollow roller structure, and the electrostatic eliminator and the electrostatic generator are arranged in the hollow part of the electrostatic adsorption roller. The electrostatic adsorption roller comprises an electrostatic adsorption roller base body, a convex structure, a wire and a conductor. The convex structure and the wire are arranged on the outer surface of the electrostatic adsorption roller base body, and the conductor is arranged on the inner surface of the electrostatic adsorption roller base body. The device can effectively control the directional arrangement of insulating conductive particles, ensure that there is only one conductive particle in each vertical channel, and improve the conduction performance. Meanwhile, the electrostatic voltage can be accurately controlled to adapt to different types of conductive particles, the loss rate of the insulating conductive particles is greatly reduced, the process flow is simplified, the loss rate is reduced, and continuous production is supported, thereby reducing the cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of anisotropic conductive adhesive film, and relates to a device for preparing an array type ACF adhesive film based on electrostatic adsorption and a preparation method thereof. BACKGROUND

[0002] ACF (Anisotropic Conductive Film) is a special film material that has conductive properties in the vertical direction and insulating properties in the horizontal direction, as well as good adhesive properties. These characteristics make ACF widely used in the electronics industry, especially in the manufacturing process of display materials and semiconductor components, such as liquid crystal displays (LCD), organic light-emitting diode (OLED) screens, etc.

[0003] In traditional ACF, conductive particles (usually metal or conductive polymer-coated microspheres) are randomly distributed in the adhesive film. This random distribution can lead to inconsistent numbers of conductive particles between vertical electrodes, affecting the consistency of the conduction performance. In addition, during the process of applying pressure to bond the adhesive film to the circuit board, excess conductive particles can be squeezed between horizontal electrodes, which may cause short circuits. To solve this problem, ACF uses conductive particles coated with an insulating layer, but this increases production costs and easily damages the insulating layer during conventional high-speed mixing processes, reducing its insulating performance.

[0004] To overcome the above problems, researchers have begun to explore the preparation technology of array type ACF adhesive film. This technology achieves directional arrangement of conductive particles by designing specific groove structures, ensuring that there is only one conductive particle in each vertical channel, thereby ensuring stable electrical connection. However, the array type ACF adhesive film technology in the prior art still has some limitations, for example, different pore sizes of grooves need to be customized for different sizes of conductive particles, which undoubtedly increases the complexity of the production process and also increases costs.

[0005] In view of the above challenges, it is particularly important to develop a new type of array type ACF adhesive film preparation method. On the basis of achieving effective directional arrangement of conductive particles, it does not need to rely on grooves with specific pore sizes and is suitable for conductive particles of different sizes, improving process flexibility; at the same time, it can reduce the consumption of expensive insulating layer conductive particles and reduce costs; while ensuring good electrical performance, it simplifies the production process and improves production efficiency. SUMMARY

[0006] The present application provides a device for preparing an array type ACF adhesive film based on electrostatic adsorption and a preparation method thereof to solve the problems of array type ACF adhesive film in the prior art.

[0007] The application achieves the above-mentioned purpose by means of the following technical solutions.

[0008] The device for preparing arrayed ACF adhesive film based on electrostatic adsorption comprises an electrostatic adsorption roller, an electrostatic eliminator and an electrostatic generator.

[0009] The electrostatic adsorption roller is a hollow roller structure, and the electrostatic eliminator and the electrostatic generator are arranged in the hollow part of the electrostatic adsorption roller.

[0010] The electrostatic adsorption roller comprises an electrostatic adsorption roller base, a protruding structure, a wire and a conductor; the protruding structure and the wire are arranged on the outer surface of the electrostatic adsorption roller base, and the conductor is arranged on the inner surface of the electrostatic adsorption roller base.

[0011] Preferably, the electrostatic adsorption roller base is made of insulating material, and the insulating material comprises one or more of polytetrafluoroethylene resin, polypropylene resin and polyacrylate.

[0012] Preferably, the protruding structure is a needle-shaped metal protruding structure, and the protruding diameter of the needle-shaped metal protruding structure is 5-10 μm, and the length-diameter ratio is (5-20):1.

[0013] Preferably, the outer surface of the electrostatic adsorption roller base comprises 4-100 rows of parallel protruding structures, and each row comprises 1-100 protruding structures.

[0014] Preferably, in the protruding structures on the outer surface of the electrostatic adsorption roller base, the protruding structures in the same row are connected by the wires on the outer surface, and the wires are connected with the conductor on the inner surface of the electrostatic adsorption roller base; the protruding structures in different rows are insulated from each other.

[0015] Preferably, the number of the wires and the conductor corresponds to the number of rows of protruding structures.

[0016] Preferably, the protruding structures in adjacent two rows are staggered, the distance between the adjacent two protruding structures in the same row is 10-20 μm, and the distance between the adjacent two rows is 10-20 μm.

[0017] Preferably, the electrostatic generator and the electrostatic eliminator are plate-shaped, and are attached to the conductor on the inner surface of the electrostatic adsorption roller base, and the electrostatic generator and the electrostatic eliminator are insulated from each other.

[0018] Preferably, the electrostatic adsorption roller rotates around the center of the roller, the protruding structures and the wires on the outer surface of the electrostatic adsorption roller base and the conductor on the inner surface of the electrostatic adsorption roller rotate with the electrostatic adsorption roller, and the electrostatic generator and the electrostatic eliminator remain stationary.

[0019] The application achieves the above-mentioned purpose by means of the following technical solutions.

[0020] A preparation method of array type ACF adhesive film using the above device, the preparation comprising the following steps:

[0021] (1) The conductive particles are spread on the plane below the electrostatic adsorption roller, so that the protruding structure on the electrostatic adsorption roller can adsorb the conductive particles spread on the plane below by electrostatic adsorption technology;

[0022] (2) In the process of rotation, the conductor on the inner surface of the electrostatic adsorption roller generates static electricity when contacting the static electricity generator, and the static electricity is conducted to the protruding structure on the outer surface through the wire, and the protruding structure adsorbs the conductive particles on the plane below by electrostatic adsorption and rotates with the electrostatic adsorption roller;

[0023] (3) An NCF adhesive film is arranged above the electrostatic adsorption roller and runs in the same direction as the electrostatic adsorption roller, and the protruding structure adsorbed with the conductive particles rotates and runs to the above with the electrostatic adsorption roller, so that the conductive particles contact the NCF adhesive film;

[0024] (4) The electrostatic adsorption roller continues to rotate, and when the protruding structure on the outer surface is separated from the NCF adhesive film, the conductor on the inner surface simultaneously contacts the static electricity eliminator to eliminate static electricity, so that the conductive particles stay on the NCF adhesive film, and an array type ACF adhesive film is obtained.

[0025] Preferably, in the step (1), the conductive particles are conductive particles coated with an insulating layer, and the diameter is 5-20 μm.

[0026] Preferably, in the step (1), the height difference between the protruding structure on the electrostatic adsorption roller and the conductive particles spread on the plane below is 0.05-1 mm at the lowest point.

[0027] Preferably, in the step (2), the rotation speed of the electrostatic adsorption roller is 3-10 m / min.

[0028] Preferably, in the step (2), the static voltage of the static electricity generator is controlled to be 100-10000 V, so that only one conductive particle is adsorbed on each protruding structure.

[0029] Preferably, in the step (3), the NCF adhesive film is a non-conductive adhesive film without conductive particles. That is, the difference between the NCF adhesive film and the normal ACF adhesive film is that the NCF adhesive film does not contain conductive particles.

[0030] Preferably, in the step (3), the thickness deviation of the NCF adhesive film is ≤2 μm.

[0031] Optionally, in the step (4), after the conductive particles stay on the NCF adhesive film, a secondary embossing method can be used to enhance the adhesion with the adhesive film.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] 1、The device for preparing array type ACF adhesive film based on electrostatic adsorption provided by the present application can effectively realize the directional arrangement of insulating conductive particles in the ACF adhesive film through the electrostatic adsorption technology, ensure that there is only one conductive particle in each vertical channel, and thus ensure the good conduction performance of the ACF adhesive film.

[0034] 2、The device for preparing array type ACF adhesive film based on electrostatic adsorption provided by the present application can adsorb insulating conductive particles of different sizes and weights by precisely controlling the size of the electrostatic voltage, which means that the technology can adapt to a wider range of particle types and improve the flexibility of the process.

[0035] 3、Compared with the traditional high-speed mixing method, the electrostatic adsorption method adopted by the present application will not damage the insulating layer of the conductive particles, effectively ensure the insulating performance of the conductive particles, greatly reduce the loss rate of the insulating conductive particles, and reduce the preparation cost. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is a flowchart of the preparation of array type ACF by the electrostatic adsorption method of the present application.

[0037] Among them: 1 is a conductive particle; 2 is an electrostatic generator; 3 is an electrostatic eliminator; 4 is an electrostatic adsorption roller; 5 is an NCF adhesive film; 6 is an array type ACF adhesive film.

[0038] Figure 2 It is a cross-sectional view of the electrostatic adsorption roller of the present application.

[0039] Among them: 4 is an electrostatic adsorption roller; 41 is a convex structure; 42 is a wire; 43 is an electrostatic adsorption roller base; 44 is a conductor. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be further described and explained in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate the present application and not to limit the scope of the present application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content of the present application, and these equivalent forms also fall within the scope of the claims attached hereto.

[0041] As Figure 1 and Figure 2As shown, wherein: 1 is a conductive particle; 2 is an electrostatic generator; 3 is an electrostatic eliminator; 4 is an electrostatic adsorption roller; 5 is an NCF adhesive film; 6 is an arrayed ACF adhesive film; 41 is a protruding structure; 42 is a wire; 43 is an electrostatic adsorption roller base; 44 is a conductor.

[0042] From Figure 1 and Figure 2 It can be seen that the device for preparing arrayed ACF adhesive film 6 by electrostatic adsorption provided by the present application comprises an electrostatic adsorption roller 4, an electrostatic eliminator 3 and an electrostatic generator 2; the electrostatic adsorption roller 4 is a hollow roller structure, the electrostatic eliminator 3 and the electrostatic generator 2 are arranged in the hollow part of the electrostatic adsorption roller 4; the electrostatic adsorption roller 4 comprises an electrostatic adsorption roller base 43, protruding structures 41, wires 42 and conductors 44; the protruding structures 41 and the wires 42 are arranged on the outer surface of the electrostatic adsorption roller base 43, and the conductors 44 are arranged on the inner surface of the electrostatic adsorption roller base 43; the protruding structures 41 are needle-shaped metal protruding structures; among the protruding structures 41 on the outer surface of the electrostatic adsorption roller base 43, the protruding structures 41 in the same row are connected by the wires 42 on the outer surface, and the wires 42 are connected with the conductors 44 on the inner surface of the electrostatic adsorption roller base 43; the protruding structures 41 in different rows are insulated from each other; the number of the wires 42 and the conductors 44 corresponds to the number of rows of the protruding structures 41; the protruding structures 41 in adjacent two rows are staggered; the electrostatic generator 2 and the electrostatic eliminator 3 are plate-shaped and are attached to the conductors 44 on the inner surface of the electrostatic adsorption roller base 43, and the electrostatic generator 2 and the electrostatic eliminator 3 are insulated from each other; the electrostatic adsorption roller 4 rotates around the center of the roller; the protruding structures 41 and the wires 42 on the outer surface of the electrostatic adsorption roller base 43, and the conductors 44 on the inner surface of the electrostatic adsorption roller base 43 rotate with the electrostatic adsorption roller 4; the electrostatic generator 2 and the electrostatic eliminator 3 remain stationary.

[0043] From Figure 1 and Figure 2It can also be seen that the preparation method of the array type ACF prepared by the above device comprises the following steps: the conductive particles 1 are dispersed and laid on the plane below the electrostatic adsorption roller 4; in the process of rotation, the conductor 44 on the inner surface of the electrostatic adsorption roller base 43 generates static electricity when contacting the static electricity generator 2, the static electricity is conducted to the protruding structure 41 on the outer surface through the wire 42, the protruding structure 41 adsorbs the conductive particles 1 on the plane below through electrostatic adsorption, and rotates together with the electrostatic adsorption roller 4; the NCF adhesive film 5 is arranged above the electrostatic adsorption roller 4 and runs in the same direction as the electrostatic adsorption roller 4, the protruding structure 41 adsorbing the conductive particles 1 rotates and runs to the upper side with the electrostatic adsorption roller 4, and then the conductive particles 1 and the NCF adhesive film 5 are contacted; the electrostatic adsorption roller 4 continues to rotate, the protruding structure 41 on the outer surface is separated from the NCF adhesive film 5, the conductor 44 on the inner surface contacts the static electricity eliminator 3 at the same time to eliminate static electricity, so that the conductive particles 1 stay on the NCF adhesive film 5, and the array type ACF adhesive film 6 is obtained.

[0044] Embodiment 1

[0045] The device for preparing the array type ACF adhesive film by electrostatic adsorption in this embodiment comprises an electrostatic adsorption roller, a static electricity eliminator and a static electricity generator; the electrostatic adsorption roller is a hollow roller structure, the static electricity eliminator and the static electricity generator are arranged in the hollow part of the electrostatic adsorption roller; the electrostatic adsorption roller comprises an electrostatic adsorption roller base, a protruding structure, a wire and a conductor; the protruding structure and the wire are arranged on the outer surface of the electrostatic adsorption roller base, and the conductor is arranged on the inner surface of the electrostatic adsorption roller base; the electrostatic adsorption roller base is made of polycarbonate material; the protruding structure is a needle-shaped metal protruding structure, the protruding diameter of the needle-shaped metal protruding structure is 5 μm, and the length-diameter ratio is 5:1; the outer surface of the electrostatic adsorption roller base comprises 40 rows of parallel protruding structures, and each row comprises 12 protruding structures; among the protruding structures on the outer surface of the electrostatic adsorption roller base, the protruding structures in the same row are connected through the wires on the outer surface, and the wires are connected with the conductor on the inner surface of the electrostatic adsorption roller; the protruding structures in different rows are insulated from each other; the number of the wires and the conductor corresponds to the number of rows of the protruding structures; the adjacent two rows of protruding structures are staggered, the distance between the adjacent two protruding structures in the same row is 10 μm, and the distance between the adjacent two rows is 10 μm; the static electricity generator and the static electricity eliminator are plates and are attached to the conductor on the inner surface of the electrostatic adsorption roller, and the static electricity generator and the static electricity eliminator are insulated from each other; the electrostatic adsorption roller rotates around the center of the roller; the protruding structure and the wire on the outer surface of the electrostatic adsorption roller and the conductor on the inner surface rotate with the electrostatic adsorption roller; the static electricity generator and the static electricity eliminator remain stationary.

[0046] The preparation method of the array type ACF prepared by the above device in this embodiment comprises the following steps:

[0047] (1) The conductive particles (10 μm) coated with insulation layer are spread on the plane under the electrostatic adsorption roller; and the height difference between the lowest point of the protrusions on the electrostatic adsorption roller and the spread conductive particles is adjusted to be 0.15 mm.

[0048] (2) The electrostatic adsorption roller rotates clockwise at a speed of 4 m / min; during the rotation, the conductors on the inner surface of the electrostatic adsorption roller generate static electricity when contacting the static electricity generator, the static electricity is conducted to the protrusions on the outer surface through the conductive wire, the protrusions adsorb the conductive particles on the plane below through electrostatic adsorption, the static voltage of the static electricity generator is controlled to be 400 V, so that only one conductive particle is adsorbed on each protrusion and rotates with the electrostatic adsorption roller;

[0049] (3) An NCF film without conductive particles is arranged above the electrostatic adsorption roller and runs in the same direction as the electrostatic adsorption roller, the protrusions adsorbing the conductive particles rotate and run to the upper side with the electrostatic adsorption roller, and then the conductive particles contact the NCF film.

[0050] (4) The electrostatic adsorption roller continues to rotate, when the protrusions on the outer surface are separated from the NCF film, the conductors on the inner surface contact the static electricity eliminator to eliminate static electricity at the same time, so that the conductive particles stay on the NCF film, and an array type ACF film is obtained.

[0051] Example 2

[0052] The device for preparing the array ACF adhesive film by electrostatic adsorption in the embodiment comprises an electrostatic adsorption roller, an electrostatic eliminator and an electrostatic generator; the electrostatic adsorption roller is a hollow roller structure, the electrostatic eliminator and the electrostatic generator are arranged in the hollow part of the electrostatic adsorption roller; the electrostatic adsorption roller comprises an electrostatic adsorption roller base, a protruding structure, a wire and a conductor; the protruding structure and the wire are arranged on the outer surface of the electrostatic adsorption roller base, and the conductor is arranged on the inner surface of the electrostatic adsorption roller base; the electrostatic adsorption roller base is made of polytetrafluoroethylene material; the protruding structure is a needle-shaped metal protruding structure, the protruding diameter of the needle-shaped metal protruding structure is 10 μm, and the length-diameter ratio is 6:1; the outer surface of the electrostatic adsorption roller base comprises 60 rows of parallel protruding structures, and each row comprises 20 protruding structures; in the protruding structures on the outer surface of the electrostatic adsorption roller base, the protruding structures in the same row are connected through the wires on the outer surface, and the wires are connected with the conductor on the inner surface of the electrostatic adsorption roller base; the protruding structures in different rows are insulated from each other; the number of the wires and the conductor corresponds to the number of rows of the protruding structures; the protruding structures in adjacent two rows are staggered, the distance between the two adjacent protruding structures in the same row is 20 μm, and the distance between the two adjacent rows is 20 μm; the electrostatic generator and the electrostatic eliminator are plate-shaped, and are attached to the conductor on the inner surface of the electrostatic adsorption roller, and are insulated from each other; the electrostatic adsorption roller rotates around the center of the roller; the protruding structure and the wire on the outer surface of the electrostatic adsorption roller, and the conductor on the inner surface of the electrostatic adsorption roller rotate with the electrostatic adsorption roller; the electrostatic generator and the electrostatic eliminator remain stationary.

[0053] The preparation method of the array ACF in the embodiment comprises the following steps:

[0054] (1) The conductive particles (20 μm) coated with an insulating layer are dispersed and laid on the plane below the electrostatic adsorption roller; and the height difference between the protrusions on the electrostatic adsorption roller and the laid conductive particles is adjusted to be 0.45 mm when the protrusions are at the lowest point.

[0055] (2) The electrostatic adsorption roller rotates clockwise at a speed of 6 m / min; during the rotation, the conductor on the inner surface of the electrostatic adsorption roller base generates static electricity when contacting the electrostatic generator, the static electricity is conducted to the protruding structures on the outer surface through the wires, the protruding structures are controlled to adsorb one conductive particle each through the conductive particles on the plane below the electrostatic adsorption roller, and the electrostatic voltage of the electrostatic generator is controlled to be 2000 V, so that each protruding structure adsorbs one conductive particle and rotates with the electrostatic adsorption roller;

[0056] (3) An NCF adhesive film without conductive particles is arranged above the electrostatic adsorption roller and runs in the same direction as the electrostatic adsorption roller; the protruding structures adsorbing the conductive particles rotate and run to the upper part of the electrostatic adsorption roller, and then the conductive particles and the NCF adhesive film are contacted.

[0057] (4) The electrostatic adsorption roller continues to rotate, and when the convex structure on the outer surface is separated from the NCF adhesive film, the conductor on the inner surface simultaneously contacts the electrostatic eliminator to eliminate static electricity, so that the conductive particles stay on the NCF adhesive film, and an array type ACF adhesive film is obtained.

[0058] Aspects, embodiments, features of the present application are to be considered illustrative only and not restrictive in all respects. The scope of the present application is defined only by the claims. Other embodiments, modifications, and uses can be apparent to those skilled in the art without departing from the spirit and scope of the claimed application.

[0059] In the preparation method of the present application, the order of each step is not limited to the listed order, and for those skilled in the art, the order of each step can be changed without creative labor, which is within the protection scope of the present application. In addition, two or more steps or actions can be performed simultaneously.

[0060] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the embodiments of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. Here, it is not necessary and also impossible to fully exemplify all the embodiments. However, the obvious changes or variations derived from the spirit of the present application still belong to the protection scope of the present application, and any additional limitation is contrary to the spirit of the present application.

Claims

1. An apparatus for preparing an array-type ACF film based on electrostatic adsorption, characterized in that, The device includes an electrostatic adsorption roller, an electrostatic eliminator, and an electrostatic generator; the electrostatic adsorption roller is a hollow roller structure, and the electrostatic eliminator and the electrostatic generator are disposed in the hollow part of the electrostatic adsorption roller. The electrostatic adsorption roller includes an electrostatic adsorption roller base, a raised structure, a wire, and a conductor; the raised structure and the wire are disposed on the outer surface of the electrostatic adsorption roller base, and the conductor is disposed on the inner surface of the electrostatic adsorption roller base. The protrusion structure is a needle-shaped metal protrusion structure, and the outer surface of the electrostatic adsorption roller substrate includes 4 to 100 rows of parallel protrusion structures, with 1 to 100 protrusion structures in each row. In the raised structure on the outer surface of the electrostatic adsorption roller substrate, the raised structures in the same row are connected by wires on the outer surface, and the wires are then connected to the conductors on the inner surface of the electrostatic adsorption roller substrate; the raised structures in different rows are insulated from each other. Furthermore, the number of the wires and conductors corresponds to the number of rows of the protruding structures; The raised structures in adjacent rows are arranged alternately; The electrostatic generator and electrostatic eliminator are plate-shaped and are attached to the conductor on the inner surface of the electrostatic adsorption roller substrate. The electrostatic generator and electrostatic eliminator are insulated from each other. The electrostatic adsorption roller rotates around the center of the roller; the raised structure and wires on the outer surface of the electrostatic adsorption roller substrate and the conductor on the inner surface rotate with the electrostatic adsorption roller; the electrostatic generator and the electrostatic eliminator remain fixed.

2. The apparatus for preparing an array-type ACF film based on electrostatic adsorption according to claim 1, characterized in that, The substrate of the electrostatic adsorption roller is made of an insulating material, which includes one or more of polytetrafluoroethylene resin, polypropylene resin, and polyacrylate.

3. The apparatus for preparing an array-type ACF film based on electrostatic adsorption according to claim 1, characterized in that, The diameter of the needle-like metal protrusion structure is 5~10μm, and the aspect ratio is (5~20):

1.

4. The apparatus for preparing an array-type ACF film based on electrostatic adsorption according to claim 1, characterized in that, The protruding structures in two adjacent rows are arranged alternately. The distance between two adjacent protruding structures in the same row is 10~20μm, and the distance between two adjacent rows is 10~20μm.

5. A method for preparing an array-type ACF film using the apparatus described in any one of claims 1 to 4, characterized in that, The preparation includes the following steps: (1) Disperse and lay the conductive particles on the plane below the electrostatic adsorption roller so that the raised structure on the electrostatic adsorption roller can adsorb the conductive particles laid on the plane below through electrostatic adsorption technology. (2) During the rotation, the conductor on the inner surface of the electrostatic adsorption roller base generates static electricity when it comes into contact with the electrostatic generator. The static electricity is conducted to the raised structure on the outer surface through the wire. The raised structure electrostatically adsorbs the conductive particles laid flat on the lower plane and rotates together with the electrostatic adsorption roller. (3) An NCF film running in the same direction as the electrostatic adsorption roller is set above the electrostatic adsorption roller. After the protruding structure that adsorbs conductive particles moves to the top with the rotation of the electrostatic adsorption roller, the conductive particles and the NCF film come into contact. (4) The electrostatic adsorption roller continues to rotate. When the raised structure on the outer surface is detached from the NCF film, the conductor on the inner surface simultaneously contacts the electrostatic eliminator to eliminate static electricity, so that the conductive particles remain on the NCF film and an array-type ACF film is obtained.

6. The preparation method according to claim 5, characterized in that, In step (1), the conductive particles are conductive particles coated with an insulating layer, with a diameter of 5~20μm.

7. The preparation method according to claim 5, characterized in that, The height difference between the raised structure on the electrostatic adsorption roller and the conductive particles laid flat on the plane below at the lowest point is set to 0.05~1mm.

8. The preparation method according to claim 5, characterized in that, In step (2), the rotation speed of the electrostatic adsorption roller is 3~10m / min.

9. The preparation method according to claim 5, characterized in that, The electrostatic voltage of the electrostatic generator is controlled to be 100~10000V, so that only one conductive particle is adsorbed on each protruding structure.

10. The preparation method according to claim 5, characterized in that, In step (3), the NCF film is a non-conductive film that does not contain conductive particles; And / or, the thickness deviation of the NCF film is ≤2μm.

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