MANUFACTURING METHOD FOR ELECTROMAGNETIC SHIELDING FILM AND ELECTROMAGNETIC SHIELDING WINDOW

Abstract

Provided is a method for manufacturing an electromagnetic shielding film, which includes: step 1), coating a photoresist on a conductive substrate, and then forming a pattern structure on the conductive substrate through a photolithography process; step 2), growing a metal layer in the pattern structure through a selective electrodeposition process to form a metal pattern structure; and step 3), embedding the metal pattern structure in a flexible base material through an imprinting process to form an electromagnetic shielding film. A method for manufacturing an electromagnetic shielding window is also provided.

Claims

1. A method for manufacturing an electromagnetic shielding film, comprising: step 1), coating a photoresist on a conductive substrate, and then forming a pattern structure on the conductive substrate through a photolithography process; step 2), growing a metal layer in the pattern structure through a selective electrodeposition process to form a metal pattern structure; and step 3), embedding the metal pattern structure in a flexible base material through an imprinting process to form an electromagnetic shielding film.

2. The method for manufacturing an electromagnetic shielding film according to claim 1, wherein the step 3) comprises: coating a polyimide solution on the conductive substrate; forming a film through thermal curing; and separating the film and the conductive substrate to obtain the electromagnetic shielding film.

3. The method for manufacturing an electromagnetic shielding film according to claim 1, wherein the step 3) comprises: coating an ultraviolet curing adhesive on the conductive substrate, and covering a PET film on the ultraviolet curing adhesive; irradiating the ultraviolet curing adhesive with an ultraviolet lamp, wherein the ultraviolet curing adhesive is cured and is adhered onto the PET film after irradiation; and separating the PET film and the conductive substrate to obtain the electromagnetic shielding film.

4. The method for manufacturing an electromagnetic shielding film according to claim 1, wherein the step 3) comprises: covering a COC film on the conductive substrate; applying temperature and pressure on the COC film; and separating the COC film and the conductive substrate to obtain the electromagnetic shielding film.

5. The method for manufacturing an electromagnetic shielding film according to claim 1, wherein step 21) is further provided between the step 2) and the step 3), the step 21) comprises: placing the conductive substrate having the metal pattern structure into stripping liquid to strip the photoresist on the conductive substrate except for the metal pattern structure.

6. The method for manufacturing an electromagnetic shielding film according to claim 1, wherein the pattern structure is a grid structure.

7. The method for manufacturing an electromagnetic shielding film according to claim 6, wherein the grid structure has a periodic arrangement or a non-periodic arrangement.

8. The method for manufacturing an electromagnetic shielding film according to claim 1, wherein the conductive substrate is a flexible substrate or a rigid substrate.

9. A method for manufacturing an electromagnetic shielding window, comprising: step 1), coating a photoresist on a conductive substrate, and then forming a pattern structure on the conductive substrate through a photolithography process; step 2), growing a metal layer in the pattern structure through a selective electrodeposition process to form a metal pattern structure; and step 3), arranging the conductive substrate having the metal pattern structure between two pieces of glass to form an electromagnetic shielding window, or attaching the conductive substrate having the metal pattern structure to one piece of glass to form an electromagnetic shielding window.

10. The method for manufacturing an electromagnetic shielding window according to claim 9, wherein the conductive substrate having the metal pattern structure is composited with a surface of a mold by a solvent adhesive layer, to be molded.

11. The method for manufacturing an electromagnetic shielding film according to claim 2, wherein step 21) is further provided between the step 2) and the step 3), the step 21) comprises: placing the conductive substrate having the metal pattern structure into stripping liquid to strip the photoresist on the conductive substrate except for the metal pattern structure.

12. The method for manufacturing an electromagnetic shielding film according to claim 3, wherein step 21) is further provided between the step 2) and the step 3), the step 21) comprises: placing the conductive substrate having the metal pattern structure into stripping liquid to strip the photoresist on the conductive substrate except for the metal pattern structure.

13. The method for manufacturing an electromagnetic shielding film according to claim 4, wherein step 21) is further provided between the step 2) and the step 3), the step 21) comprises: placing the conductive substrate having the metal pattern structure into stripping liquid to strip the photoresist on the conductive substrate except for the metal pattern structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG. 1 is a schematic flow chart of an electromagnetic shielding film of the present disclosure;

[0048] FIG. 2a is a top view of an electromagnetic shielding film according to an embodiment of the preset disclosure;

[0049] FIG. 2b is a side view of an electromagnetic shielding film according to an embodiment of the preset disclosure;

[0050] FIG. 3 is a schematic structural diagram of an electromagnetic shielding film according to another embodiment of the present disclosure;

[0051] FIG. 4a is a schematic structural diagram of an electromagnetic shielding window according to an embodiment of the present disclosure;

[0052] FIG. 4b is a schematic structural diagram of an electromagnetic shielding window according to another embodiment of the present disclosure;

[0053] FIG. 4c is a schematic structural diagram of an electromagnetic shielding device according to an embodiment of the present disclosure; and

[0054] FIG. 5 is a schematic structural diagram of an electromagnetic shielding film having a non-periodic metal grid according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0055] Referring to the drawings, the preferred embodiments of the present disclosure will be described in detail below.

[0056] The technical solution of this embodiment is comprehensively described as follows. A micro metal grid is embedded in a PI material by a micro-nano processing technology, which is flexible, not easy to scratch, high temperature resistance, good transparency and strong electromagnetic shielding effectiveness. Specific technical design is as follows. A grid structure is formed on a conductive substrate (conductive substrate material such as metal, metallized flexible conductive film, ITO and FTO glass) by a photolithography technique (such as laser direct writing, ultraviolet exposure and electron beam exposure). A metal layer (such as nickel, copper, gold) is grew in the grid structure by a selective electrodeposition process. The metal grid structure is embedded into a flexible substrate material by a nano-imprinting technology (hot imprinting and film inversion technology) to form an electromagnetic shielding film.

[0057] The technical solution of this embodiment is specifically as follows.

[0058] 1) A preset grid is fabricated on a conductive substrate. According to the performance requirements of the electromagnetic shielding film (such as light transmittance, shielding effectiveness and high diffraction order extinction), a layout of the grid structure (such as periodic arrangement of hexagonal honeycombs, squares, parallelograms and non-periodic arrangement of arbitrary polygons), a line width of the grid (from 300 nm to 10 μm), a spacing of the grid (from 10 μm to 500 μm) and other parameters are designed, and then a pattern structure is formed on the conductive substrate coated with a photoresist by a micro-nanostructure patterning technology (such as laser direct writing, ultraviolet exposure and electron beam exposure).

[0059] 2) A metal grid layer is grew by selective deposition. The patterned conductive substrate is placed on a cathode of an electrodeposition bath, and a metal material to be deposited is placed on an anode of the electrodeposition bath. With selective deposition of the electrodeposition, the metal material is deposited in a trench of the grid where the conductive substrate is exposed, and no electrodeposited layer is formed in an area covered by the photoresist. By controlling current intensity (from 500 mA to 50 A) attached to the electrode, deposition time (from 20 s to 6000 s), distance between the cathode and the anode (from 20 mm to 300 mm) and so on, a deposition thickness (from 300 nm to 10 μm) of the metal material may be controlled.

[0060] 3) An electromagnetic shielding film having embedded metal grid is fabricated. The conductive substrate of the deposited metal grid layer is placed into stripping liquid, the photoresist on the conductive substrate is striped and only the metal grid deposited on the conductive substrate is retained. Using nano-imprinting technique (such as hot imprinting and film inversion technique), the metal grid on the conductive substrate is embedded in a transparent and flexible substrate to form an electromagnetic shielding film.

[0061] 4) The thickness of the deposited layer is affected by energization time, current intensity and electrode spacing, and the greater the thickness of the deposited layer is, the higher the conductivity is. The thickness (from 300 nm to 10 μm) of the deposited layer may be controlled by adjusting the parameters of the electrodeposition. The transmittance of the electromagnetic shielding film depends on the proportion (less than 5%) of the metal grid portion to the entire portion, the wire width (from 200 nm to 10 μm) of the grid is restricted by the trench, which can realize the production of electromagnetic shielding film with transmittance more than 95% and shielding effectiveness more than 60 dB.

[0062] 5) An electromagnetic shielding film is formed by a film inversion technology. Polyimide solution PI is coated on the deposited and stripped conductive substrate, after a film is formed by thermal curing, the film is separated from the conductive substrate and the thickness of the PI film is only a few micrometers to several ten micrometers (from 5 μm to 15 μm). The ultra-thin electromagnetic shielding film can be attached to a complex structure surface of any shape to produce an electromagnetic shielding device having complex topography requirements. At the same time, the electromagnetic shielding film has high temperature resistance.

[0063] 6) An electromagnetic shielding film may be produced by a nano-imprinting technology. The ultraviolet curing adhesive is coated on the deposited and stripped conductive substrate, the PET film is covered on the ultraviolet curing adhesive, and the ultraviolet curing adhesive is irradiated with an ultraviolet lamp. The ultraviolet adhesive is cured and is adhered on the PET substrate after irradiation. The PET film is separated from the conductive substrate to obtain the metal grid type electromagnetic shielding film embedded in an ultraviolet curing adhesive.

[0064] 7) An electromagnetic shielding film may be made by a hot imprinting technology. A COC film is covered on the deposited and stripped conductive substrate, and a certain temperature (exceeding the glass transition temperature of the COC film) and pressure are applied. The COC film and the conductive substrate are separated to obtain the electromagnetic shielding film embedded in the COC.

[0065] 8) The substrate may be, but is not limited to, flexible films such as PI, PET, PEN, COC. Since the metal grid structure is embedded in the flexible substrate, the attenuation of the electromagnetic shielding effectiveness is less than 5% when the bending radius is less than 3 mm, and the film exhibits excellent scratch resistance.

[0066] Specific embodiments are described as follows.

[0067] In a first embodiment, it is manufactured an ultra-thin metal grid electromagnetic shielding film. The production process is shown in FIG. 1. First, the layout of the metal grid structure, which maybe periodic arrangement of hexagonal honeycombs, squares, rectangles, parallelograms, triangles or arbitrary polygons arrangement, the line width of the grid (from 300 nm to 10 μm), the spacing of the grid (from 1 μm to 500 μm) and other parameters are designed based on the need of shielding effectiveness. Then a pattern grid structure is formed on the conductive substrate coated with the photoresist by patterning technology (such as laser direct writing, ultraviolet exposure and electron beam exposure). The patterned conductive substrate is placed on a cathode of the electrodeposition bath, and the metal material (such as nickel, copper, gold, aluminum and silver) to be deposited is placed on an anode of the electrodeposition bath. By the selective deposition of electrodeposition, the metal of the anode is gradually deposited in a conductive grid trench of the cathode by cations, and no electrodeposited layer is formed in the region covered by the photoresist. At this time, the sidewall of the photoresist trench on the conductive substrate has a certain depth (from 200 nm to 10 μm), then the deposition process of the cation is confined in the conductive trench of 300 nm to 10 μm, and the shape and line width of the conductive trench are the same as the shape and line width of the grid trench. By controlling the current intensity (from 500 mA to 20 A) attached to the electrode, the deposition time (from 20 s to 4000 s), the distance (from 20 mm to 300 mm) between the cathode and the anode, and so on, the deposition thickness (from 300 nm to 3 μm) of the metal material can be controlled. Subsequently, the conductive substrate of the deposited metal grid layer is placed into stripping liquid to strip the photoresist on the conductive substrate and only retain the metal grid deposited on the conductive substrate. Then, PI polyimide solution is coated on the conductive substrate and after a film is formed by thermal curing, the film is separated from the conductive substrate to obtain an ultra-thin metal grid electromagnetic shielding film.

[0068] Depending on the coating method (such as spin coating, casting and blade coating), the thickness of the PI film can be adjusted. The thickness of the PI film is only several micrometers to a few ten micrometers (from 5 μm to 15 μm). FIG. 2a and FIG. 2b are top view and side view of the shielding film manufactured according to this method respectively. Since the metal grid structure 1 is embedded in the ultra-thin PI film 2, the shielding film may withstand a bend with a radius less than 20 μm. The metal material of the electromagnetic shielding film is a good conductor, such as nickel, copper, gold, aluminum and silver. The arrangement of the grid may be square, and in other embodiments may be a periodic arrangement of hexagons, rectangles or non-periodic arrangement. The ultra-thin electromagnetic shielding film can be attached to a complex structure surface of any shape to produce an electromagnetic shielding device having complex topography requirements.

[0069] In a second embodiment, it is manufactured a metal grip type electromagnetic shielding film embedded in an ultraviolet curing adhesive. According to the production process of an embodiment, a metal grid structure is formed on the conductive substrate by a selective electrodeposition process. According to the design requirements, the line width (from 300 nm to 10 μm) of the metal grid, the spacing (from 10 μm to 500 μm) of the grid, and the thickness (from 300 nm to 10 μm) of the metal deposition layer are formed. Subsequently, an ultraviolet curing adhesive is coated on the deposited and stripped conductive substrate, the PET film is covered on the ultraviolet curing adhesive, and the ultraviolet curing adhesive is irradiated with an ultraviolet lamp. The ultraviolet adhesive is cured and is adhered on the PET substrate 3 after irradiation. After separating the PET film from the conductive substrate, the metal grid 4 is embedded in the ultraviolet curing adhesive 5 to form an electromagnetic shielding film, as shown in FIG. 3. The transmittance of the electromagnetic shielding film depends on the proportion (less than 5%) of the metal grid portion to the entire portion, and the width (from 300 nm to 10 μm) of the grid is restricted by the trench, so that the electromagnetic shielding film may achieve a transmittance more than 95% and a shielding effectiveness more than 60 dB.

[0070] In this embodiment, the used conductive substrate may be as a flexible or rigid substrate. In a case that a flexible conductive substrate (such as flexible metal plate and metalized flexible film) is used, a roll-to-roll nano-imprinting method can be adopted in the process of transferring the metal grid structure to the PET substrate, which is more suitable for the production of electromagnetic shielding films with large image, high transmittance and high shielding effectiveness.

[0071] In a third embodiment, it is manufactured an embedded electromagnetic shielding film. According to the production process of an embodiment, a metal grid structure is formed on the conductive substrate by a selective electrodeposition process. According to the design requirements, the line width (from 300 nm to 10 μm) of the metal grid, the spacing (from 10 μm to 500 μm) of the grid, and the thickness (from 300 nm to 10 μm) of the metal deposition layer are formed. And then, a COC film is covered on the deposited and stripped conductive substrate, and a certain temperature (exceeding the glass transition temperature of COC film) and pressure are applied. The metal grid is embedded in the COC film by a hot imprinting technology. The COC film and the conductive substrate are separated to obtain the electromagnetic shielding film embedded in the COC;

[0072] In a fourth embodiment, it is manufactured a hollowed-out metal grid electromagnetic shielding film. According to the production process of an embodiment, a metal grid structure is formed on the conductive substrate by a selective electrodeposition process. According to the design requirements, the line width (from 1 μm to 10 μm) of the metal grid and the spacing (from 1 μm to 500 μm) of the grid are formed. In order to separate the hollowed-out metal grid from the conductive substrate, the thickness of the metal grid should exceed 1 μm. The hollowed-out metal grid 6 may be arranged between two pieces of glass or may be attached to the glass 7 to form an electromagnetic shielding window, as shown in FIG. 4a and FIG. 4b. In addition, as shown in FIG. 4c, the hollowed-out metal grid 6 may be composited with a surface 8 of a mold having any other shape (such as concave, convex and irregular shapes) by a solvent adhesive layer, to form a special-shaped electromagnetic shielding device.

[0073] When the metal grid electromagnetic shielding film based on the first embodiment, the second embodiment, the third embodiment and the fourth embodiment is used to realize the optical shielding window, since the line width of the metal wire grid is generally on the order of micrometer or even sub-micrometer, the structure has a strong diffraction effect on the visible light. The zeroth order diffraction light and the high-order diffraction light coexist in the transmitted light. In order to eliminate the interference of the high-order diffraction light on the imaging and detection results, the arrangement of the metal grid can be designed as, for example, a polygonal arrangement of a non-periodic structure, uniform random arrangement in all directions. FIG. 5 is a schematic structural diagram of a non-periodic polygon sequence. At this time, the high-order diffraction light is eliminated, only the zeroth order transmitted light exists, which reduces the influence on the image quality.

[0074] The above is only a preferred embodiment of the present disclosure, and it should be noted that the person skilled in the art can make various modifications and improvements without deviating from the concept of the disclosure, and these modifications and improvements are also deemed to fall into the protection scope of the present disclosure.