A method for manufacturing an embedded electromagnetic shielding metal mesh

Abstract

The application discloses a kind of embedded electromagnetic shielding metal mesh production method, comprising the following steps: making reverse mask on optical substrate;Plasma beam etching metal mesh groove;Metal thin film plating;Bottom film plating;Gel removal and cleaning;Environmental erosion resistance optical antireflection coating plating.The application makes the groove of metal mesh on the surface of optical substrate by mask production, plasma beam etching and other ways, fills metal mesh in the groove by vacuum plating, and then covers with the same film material as substrate material or, forms a whole with substrate, completely wraps metal mesh inside, and covers with optical antireflection coating with protective layer on the surface, so that optical window can realize electromagnetic shielding, optical good transmittance, environmental erosion resistance and other functions.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic information technology and relates to a method for fabricating an embedded electromagnetic shielding metal mesh on an optical substrate. Background Technology

[0002] Optical windows operating in complex electromagnetic field environments require electromagnetic shielding to protect their internal electronic components. Common methods include fabricating a conductive layer on the surface of the optical window, such as a transparent conductive film or a metal mesh. With increasingly complex battlefield environments and demands for durability in various extreme conditions, the manufacturing processes for optical windows to withstand friction, temperature shock, and high-speed impact are becoming increasingly stringent.

[0003] An embedded metal mesh grid is made by fabricating a metal mesh grid with good conductivity on the substrate of an optical window. It serves to effectively shield the optoelectronic system from external electromagnetic fields while also having good light transmittance.

[0004] 1. Patent 93242068.0, "Electromagnetic Shielding Glass," describes a structure in which a conductive metal mesh is sandwiched between two layers of glass, and a transparent conductive film is used on the outside of the glass to bond it to a metal window frame to form an electromagnetic shielding structure.

[0005] 2. Patent CN210075930U, “A fully embedded metal mesh electromagnetic shielding film”, is a metal mesh film formed between two polymer layers by heating and curing.

[0006] 3. Patent CN201408553Y, “Electromagnetic Shielding Glass”, uses an adhesive to fix an ultra-fine metal mesh between two ultra-thin glass sheets to form a “sandwich” structure electromagnetic shielding mesh glass.

[0007] All of the above methods involve bonding or heat-curing polymers to sandwich metal mesh or wire mesh between two transparent substrates, forming a "sandwich" structure. While this type of electromagnetic shielding mesh offers some abrasion resistance, it affects the light transmittance of the optical window, impacting the signal strength of the optoelectronic system. Furthermore, this adhesive or glued mesh structure is susceptible to damage from high temperatures, high-speed impacts, and other environmental factors, leading to separation of the two substrate layers, which is irreparable once damaged.

[0008] 4. Patent CN103687462A, "Wide-Spectrum Electromagnetic Shielding Window," proposes a periodic two-layer metal mesh embedded in the substrate surface of the window. The metal mesh materials are a material with good magnetic permeability and a material with good electrical conductivity, respectively. This electromagnetic shielding window can provide a 20dB shielding effect against electromagnetic waves in the 10MHz-18MHz frequency band, and the outer protective layer provides some protection against environmental corrosion. However, the patent does not mention a specific manufacturing method, and the bonding strength between the protective layer film material and the substrate material can be damaged by impacts during high-speed flight, leading to the exposure and damage of the metal mesh. Furthermore, the patent does not propose a solution to improve the optical transmittance of the optical substrate.

[0009] 5. Patent CN103442544A, "A Method for Preparing an Embedded Electromagnetic Shielding Window," proposes using a femtosecond laser to etch periodic electromagnetic shielding grid grooves with a linewidth greater than 1µm and a depth of 1-10µm onto an infrared glass substrate. This method can fabricate an embedded electromagnetic shielding grid on infrared glass; however, the femtosecond laser etching method is extremely inefficient, suitable for fabricating small-sized windows but unsuitable for large-scale, high-volume production. Furthermore, it is not suitable for windows made of other substrate materials, such as K9 glass, multispectral ZnS (zinc sulfide), sapphire, and ZnSe (zinc selenide). Summary of the Invention

[0010] (I) Purpose of the Invention

[0011] The purpose of this invention is to provide a method for fabricating embedded metal mesh on an optical substrate that has good electromagnetic shielding, good light transmission, and good resistance to environmental corrosion. This method is applicable to optical window substrates of various materials and meets the needs of large-area, high-volume production.

[0012] (II) Technical Solution

[0013] To address the aforementioned technical problems, this invention provides a method for manufacturing an embedded electromagnetic shielding metal mesh, the method comprising the following steps:

[0014] Step 1: Fabricate a reverse mask on an optical substrate.

[0015] A mask with the opposite shape to the metal mesh is fabricated on an optical substrate through processes such as coating with photoresist, exposure, and development. The shape of the metal mesh can be periodic or non-periodic, and the pattern can be selected according to the actual application.

[0016] The optical substrate can be a multispectral ZnS substrate, a sapphire substrate, or a K9 glass substrate.

[0017] Step 2: Plasma beam etching of metal mesh trenches.

[0018] The optical substrate surface with the reverse mask fabricated in step 1 is etched using a plasma beam to form trenches with the same shape as the metal mesh. The width and depth of the trenches should be determined according to the specific parameter requirements of the metal mesh.

[0019] Step 3: Metal thin film deposition.

[0020] A metal thin film is deposited on the surface of an optical substrate with etched metal mesh trenches using vacuum deposition. The thin film material can be one or more of the following metals: Ni (nickel), Cr (cadmium), Cu (copper), Ag (silver), Au (copper), and Al (aluminum); or a transparent conductive oxide such as ITO (indium tin oxide); or a multilayer conductive film composed of a metal thin film and a transparent conductive oxide. The thickness h of the metal thin film is less than the depth H of the mesh trenches described in step 2.

[0021] Step 4: Deposition of the underlying thin film.

[0022] A vacuum deposition method is used to deposit a bottom film on the surface described in step 3. The material of the bottom film is the same as or similar to that of the optical substrate material, and the difference between the film thickness and the depth of the grid trench and the thickness of the metal film is approximately equal to d≈Hh.

[0023] When the optical substrate is a multispectral ZnS substrate, the bottom film is a ZnS film; when the optical substrate is a sapphire substrate, the bottom film is an Al2O3 film; when the optical substrate is a K9 glass substrate, the bottom film is a SiO2 film.

[0024] Step 5: Remove adhesive and clean.

[0025] After the optical components have undergone metallization in step 4 above, the adhesive is removed and the surface is cleaned. Adhesive removal methods include soaking in a adhesive remover solution, wiping, or physical polishing and grinding.

[0026] Step 6: Deposition of an optical antireflective coating with good resistance to environmental corrosion.

[0027] After cleaning in step 5, an optical antireflective coating with good resistance to environmental corrosion is deposited on the surface of the optical component using a vacuum deposition method. The wavelength range of the antireflective coating can be selected according to the specific application. The coating layer can be single-layer or multi-layer, and can be made of dielectric thin film material, semiconductor thin film material, metal thin film or composite thin film material; the outermost layer of the optical antireflective coating is a high-strength protective layer.

[0028] (III) Beneficial Effects

[0029] The method for fabricating an embedded electromagnetic shielding metal mesh grid provided by the above technical solution involves fabricating the grooves of the metal mesh grid on the surface of an optical substrate by means such as mask fabrication and plasma beam etching, filling the metal mesh grid into the grooves by means of vacuum coating, and then covering it with a thin film material that is the same as or compatible with the substrate material to form an integral body with the substrate, completely wrapping the metal mesh grid inside, and then covering the surface with an optical antireflection film with a protective layer, enabling the optical window to simultaneously achieve multiple functions such as electromagnetic shielding, good optical transmittance, and environmental erosion resistance; the fabrication method adopted in the present invention involves technologies such as photolithography mask fabrication, plasma beam etching, and vacuum coating, and these technologies are very mature in engineering applications, with clear process flows and relatively simple fabrication methods, making it easy to achieve mass production. Brief Description of the Drawings

[0030] Figure 1 is the fabrication process of the embedded electromagnetic shielding metal mesh grid;

[0031] Figure 2 is a schematic diagram of a square - structured periodic mesh grid;

[0032] Figure 3 is a schematic diagram of a "rice" - shaped structured mesh grid;

[0033] Figure 4 is a schematic diagram of a random - structured mesh grid. Detailed Embodiments

[0034] To make the objectives, content, and advantages of the present invention clearer, the following further describes the detailed embodiments of the present invention in conjunction with the drawings and embodiments.

[0035] Embodiment 1

[0036] On a multi - spectral ZnS substrate, a square periodic metal mesh grid with a side length of 300 um is fabricated. First, grooves with a line width of 5 um and a depth of 500 nm are etched on the substrate. Then, by means of vacuum coating, a metal mesh grid thin film is deposited. The mesh grid material is divided into two layers. The first layer is a NiCr alloy with a line width of 5 um and a thickness of 50 nm, and the second layer is Au with a line width of 5 um and a thickness of 200 nm. A ZnS thin film with a thickness of about 250 nm is deposited on the Au film. After removing the glue and cleaning the surface, a multi - layer high - efficiency antireflection film with a wavelength range of 3700 nm - 4800 nm is deposited on the surface, and the outermost layer is a high - strength protective layer.

[0037] Embodiment 2

[0038] A "rice"-shaped periodic metal mesh was fabricated on a sapphire substrate. First, trenches with a linewidth of 8 μm and a depth of 400 nm were etched into the substrate. Then, a metal mesh film was deposited using vacuum deposition. The mesh material consisted of two layers: the first layer was Ni with a linewidth of 8 μm and a thickness of 80 nm, and the second layer was Ag with a linewidth of 8 μm and a thickness of 220 nm. An Al₂O₃ film with a thickness of approximately 100 nm was deposited on top of the Ag film. After removing the resist and cleaning the surface, a multilayer high-efficiency antireflection coating with a wavelength range of 600 nm to 1100 nm was deposited on the surface, with a high-strength protective layer as the outermost layer.

[0039] Example 3

[0040] A randomly structured metal mesh was fabricated on a K9 glass substrate. First, trenches with a linewidth of 6 μm and a depth of 380 nm were etched into the substrate. Then, a metal mesh film with a mesh material of 250 nm Au was deposited using vacuum deposition. A SiO2 film with a thickness of approximately 130 nm was deposited on top of the Au film. After removing the resist and cleaning the surface, a multilayer high-efficiency antireflection coating with a wavelength range of 450 nm to 1100 nm was deposited on the surface, with a high-strength protective layer as the outermost layer.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing an embedded electromagnetic shielding metal mesh, characterized in that, Includes the following steps: Step 1: Fabricate a reverse mask on an optical substrate; Step 2: Plasma beam etching of metal mesh trenches; Step 3: Metal thin film deposition; Step 4: Underlying thin film deposition; Step 5: Remove adhesive and clean; Step 6: Deposition of an optical antireflective coating with environmental corrosion resistance; In step 1, a mask with the opposite shape to the metal mesh is fabricated on the optical substrate through a process of coating photoresist, exposure, and development; the shape of the metal mesh can be periodic or non-periodic. In step 1, the optical substrate is selected from multispectral ZnS substrate, sapphire substrate or K9 glass substrate; In step 2, the surface of the optical substrate with the reverse mask fabricated in step 1 is etched using a plasma beam to form grooves with the same shape as the metal mesh. In step 3, a thin metal film is deposited on the surface of the optical substrate with metal mesh grooves using vacuum deposition. In step 3, the material of the metal thin film is selected from one or more of Ni, Cr, Cu, Ag, Au, and Al, or ITO transparent conductive oxide, or a multilayer conductive film composed of metal thin film and transparent conductive oxide. In step 4, a vacuum deposition method is used to deposit a bottom film on the surface described in step 3. The material of the bottom film is the same as or similar to that of the optical substrate material. In step 4, when the optical substrate is a multispectral ZnS substrate, the bottom film is a ZnS film; when the optical substrate is a sapphire substrate, the bottom film is an Al2O3 film; when the optical substrate is a K9 glass substrate, the bottom film is a SiO2 film. In step 5, the optical components after metallization in step 4 are de-adhesive and their surfaces are cleaned. The de-adhesive removal methods include soaking in de-adhesive solution, wiping, or physical polishing or grinding. In step 6, an optical antireflective coating with environmental erosion resistance is deposited on the surface of the optical component after cleaning in step 5 using a vacuum coating method. Antireflective coatings can be single-layered or multi-layered, and can be made of dielectric thin film materials, semiconductor thin film materials, metal thin film materials, or composite thin film materials; the outermost layer of an optical antireflective coating is a high-strength protective layer.

Images