A patterned reflective film and a process for making the same

Abstract

This invention discloses a patterned reflective film and its fabrication process, belonging to the field of optical functional thin film technology. The reflective film includes a substrate layer and a reflective layer. The reflective layer is patterned to form a discontinuous reflective pattern, which includes reflective units separated by light-transmitting regions. The linewidth of the light-transmitting regions is 3-10 micrometers, and the reflective pattern can be a random grid or a gradient pixel array. This invention, by precisely designing the geometric distribution of reflective units and light-transmitting regions at the micrometer scale, utilizes the significant difference between microwave and visible light wavelengths to achieve high reflectivity in the visible light band and high transmittance in the microwave band. This fundamentally solves the contradiction between metallic decorative finishes and wireless signal transmission. The random or gradient pattern design effectively avoids moiré patterns with display pixels. The blackening process on the copper reflective layer surface can achieve various decorative colors such as blue, red, and black. This reflective film has a high yield and wide application.

Description

Technical Field

[0001] This invention relates to the field of optical functional thin film technology, and in particular to a patterned reflective film and its preparation process. Background Technology

[0002] With the rapid development of 5G communication, the Internet of Things, and smart terminals, the integrated design and metallic texture of electronic products have become important design trends. Metallized decorative films are widely used in mobile phone back covers, home appliance panels, and automotive interiors due to their high reflectivity, excellent texture, and rich color effects. However, traditional continuous metal films or metal coatings have a strong shielding effect on electromagnetic waves (especially microwave frequencies), severely hindering the transmission of wireless signals and making them unsuitable for areas requiring integrated antennas.

[0003] To resolve this contradiction, existing technologies have proposed several solutions: Physical window opening method: Reserve an area without metal coverage (antenna window) on the metal decorative film. This method destroys the overall appearance, affects aesthetics, and stress concentration is prone to occur at the window opening edges.

[0004] Metal mesh method: This method uses a regularly arranged metal mesh instead of a continuous metal layer. The mesh linewidth is typically tens of micrometers. Although it can provide a certain signal penetration capability, it has the following problems: the mesh pattern and the display pixel array are prone to periodic interference, forming obvious moiré fringes, which seriously affects the visual effect; the electromagnetic scattering of the regular mesh is directional, resulting in uneven signal transmission; when the linewidth is large (usually >15μm), the mesh is visible to the naked eye, affecting the appearance and texture of high-end products.

[0005] Transparent conductive oxide (TCO) method: such as ITO thin film. Although it has high light transmittance and certain conductivity, its reflectivity is much lower than that of metal, making it impossible to achieve a high-gloss metallic texture. In addition, it is expensive and has poor flexibility.

[0006] Metamaterial / metasurface method: This method modulates electromagnetic response through subwavelength structure design. These methods are typically complex to manufacture, extremely costly, and difficult to guarantee large-area uniformity, making them unsuitable for large-scale applications in consumer electronics.

[0007] The core contradiction in existing technologies lies in the fact that the high reflectivity and high conductivity of metals (leading to high shielding) are essentially two aspects of the same physical mechanism (the response of free electrons to electromagnetic fields). How to achieve efficient microwave transmission (ensuring communication performance) while ensuring high visible light reflectivity (achieving a metallic texture) has been a long-standing unsolved technical problem in this field.

[0008] From a physical mechanism perspective, the shielding effectiveness (SE) of a metal against electromagnetic waves mainly comes from two parts: surface reflection (R) and internal absorption (A), i.e., SE = R + A. For continuous metal films, reflection is the dominant mechanism in the microwave band, SE ≈ 168 + 10log(σ / μ0f) (dB), where σ is the conductivity and f is the frequency. This means that even very thin continuous metal layers (e.g., >100nm) can produce strong shielding >30dB. To reduce shielding, the electrical continuity of the metal layer must be disrupted, making it unable to support continuous induced current.

[0009] However, simply breaking the metal layer reduces its optical reflectivity because reflectivity is directly related to the metal's complex refractive index (n-iκ), and in particular, the extinction coefficient κ determines the metal's light absorption characteristics. When the metal layer is discontinuous, its equivalent optical constant changes, and the reflectivity decreases significantly.

[0010] Therefore, a new structural design is needed that can disrupt the electrical continuity of the metal layer in the microwave band while maintaining its metal-like optical properties in the visible light band. Summary of the Invention

[0011] In order to overcome the shortcomings of the prior art, this invention proposes a patterned reflective film and its preparation process by means of precisely controlled discontinuous pattern design, combined with specific materials and processes.

[0012] To achieve the above objectives, the present invention adopts the following technical solution: A patterned reflective film includes a substrate layer and a reflective layer formed on the substrate layer, wherein the thickness of the substrate layer is 30-100 μm; the reflective layer is made of a metal material or a metal oxide, and the thickness of the reflective layer is 480 nm-3000 nm. The reflective layer is patterned to form a discontinuous reflective pattern, which includes reflective units separated by light-transmitting regions. The linewidth of the light-transmitting regions is 3-10 micrometers, allowing electromagnetic waves to effectively penetrate the reflective film.

[0013] Preferably, the substrate layer is polyethylene terephthalate (PET) or polyimide (PI) film material, and the polymer with a thickness of 30-100μm gives the reflective film good bending resistance. 优选地，所述反射层的材料为铜或铝的金属材料或具有一定反射率的金属氧化物，所述金属氧化物包括TiO2、SiO2或Nb2O5。

[0014] Preferably, the reflective pattern is a random grid pattern, and the light-transmitting area consists of randomly distributed grid lines with a line width of 3-10 micrometers. The visible width is usually 5-10 micrometers. This design can meet the requirement of not generating signal shielding and does not affect the overall visual effect. This design can fundamentally avoid periodic interference with the regular pixel array, thereby eliminating moiré patterns.

[0015] Preferably, the reflective pattern is a gradient pixel array, and the reflective unit is a discrete reflective point with a size on the micrometer scale. The distribution density of the reflective points is designed to gradually vary according to the distance of their respective areas from the signal antenna: the closer the area is to the antenna, the sparser the distribution of reflective points and the larger the proportion of the light-transmitting area; the farther the area is from the antenna, the denser the distribution of reflective points and the smaller the proportion of the light-transmitting area. This design forms a visually uniform reflective surface on a macroscopic level, while achieving local high transmittance in signal-sensitive areas.

[0016] Furthermore, in the areas where the reflective points are densely distributed in the gradient pixel array, light-transmitting grid lines with random grid patterns are also provided as supplementary wave-transmitting channels.

[0017] Preferably, the reflective layer is a copper layer, and a blackening layer is also provided on its surface. The thickness of the blackening layer is 20-150 nm, and the color of the blackening layer is controlled to be blue, red, or black by adjusting the ratio of oxygen and nitrogen in the preparation process.

[0018] Furthermore, the blackening layer is prepared by any of the following methods: ① Preparation of blue blackening layer: Control the total pressure to 0.5-2Pa, Ar flow rate to 30-50sccm, N2 flow rate to 50-80sccm, O2 flow rate to 5-15sccm, RF or DC power density to 0.5-1.5W / cm2, plasma treatment for 30-90 seconds, real-time monitoring of color change is required, stop when the ideal blue is reached, chemical phase composition: mainly Cu3N phase, may contain a small amount of Cu2O or amorphous copper nitride, treatment at low power density for a short time to form a thin film mainly composed of copper nitride, producing a blue interference color blackening layer; ② Preparation of the red blackened layer: Control the total pressure at 0.5-2 Pa, Ar flow rate at 30-50 sccm, N2 flow rate at 30-45 sccm, O2 flow rate at 20-35 sccm, RF or DC power density at 1.0-2.0 W / cm2, plasma treatment for 60-180 seconds, chemical phase composition: mixed phase, possibly including Cu2O, CuO, Cu3N, and amorphous CuO. x Nᵧ. Through fine-tuning of ±5 sccm, a continuous variation from reddish-brown and bronze to rose gold can be achieved, with a thickness of 50-100 nm; ③ Preparation of the black blackening layer: Control the total pressure to 0.5-2 Pa, Ar flow rate to 30-50 sccm, N2 flow rate to 10-30 sccm, O2 flow rate to 40-60 sccm, RF or DC power density to 1.5-3.0 W / cm2, plasma treatment for 150-180 seconds, chemical phase composition: mainly CuO, possibly containing Cu2O, forming a relatively thick, light-absorbing copper oxide / cuprous oxide mixed layer or rough surface, achieving a matte black effect with a blackening layer thickness of 80-150 nm; the black blackening layer can also be prepared by a two-step method: the first step is to establish a base layer with a medium O2 / N2 ratio (e.g., N2 flow rate of 10-30 sccm, O2 flow rate of 40-60 sccm) (120 seconds), and the second step is to use pure oxygen or a mixed gas with an N / O volume ratio of less than 0.2 for deepening treatment (30-60 seconds).

[0019] Preferably, the reflective layer is a quarter-wavelength optical film stack formed by alternating deposition of high-refractive-index material layers and low-refractive-index material layers, and its optical thickness satisfies n·d=λ0 / 4, where n is the refractive index of the thin film material, d is its physical thickness, and λ0 is the target center wavelength (550nm in this case). This design is called a quarter-wavelength film stack.

[0020] Furthermore, the high refractive index material layer is TiO2 or Nb2O5, with n being 2.2-2.4; the low refractive index material layer is SiO2 or MgF2, with an optical refractive index n being 1.38-1.46.

[0021] Preferably, the reflective layer with a thickness of 825 nm has a light reflectivity of more than 95%, and the reflective layer with a thickness of 2 μm has a light reflectivity of more than 99%.

[0022] The present invention also proposes a process for preparing the aforementioned patterned reflective film, comprising the following steps: S1. Magnetron sputtering: A basic reflective layer is prepared on the surface of a substrate using magnetron sputtering. S2. Coating: A photocurable resin layer is coated onto the base reflective layer; S3. Photocuring: The photocurable resin layer is selectively exposed by a photomask with a preset pattern. The photomask is divided into a blocking area and a cutout area. The blocking area covers the surface of the photocurable resin layer, causing the resin in the exposed area to cross-link and cure to form a cured area, and the unexposed area to form an uncured area. The cured area covers the reflective unit of the reflective layer material, and the unexposed area forms an uncured area. Below the uncured area is the light-transmitting area of ​​the reflective layer material. S4. Etching: Sequentially remove the uncured area and the light-transmitting area below it to form a patterned structure of the reflective layer material corresponding to the preset pattern; S5. Remove the cured film: Remove the cured area to obtain a patterned reflective layer, that is, to obtain the finished patterned reflective film.

[0023] Preferably, S1 uses polyethylene terephthalate or polyimide film as the substrate layer, and plasma or ultraviolet ozone cleaning is required before use to improve adhesion.

[0024] Preferably, the preparation process of the basic reflective layer of the metallic material is as follows: Step A1. Ignition and Pre-sputtering: The substrate is transferred to the bottom of the process chamber where the target has been installed, and Ar gas (purity 99.999%) is introduced. The flow rate is precisely controlled at 20-80 sccm and adjusted by a gate valve to stabilize the working pressure of the chamber at 0.3-1.0 Pa. Apply a DC power supply to the Al or Cu target, and gradually increase the power density to 2-6 W / cm2. At this time, glow discharge will occur, and Ar will be ionized into Ar+. The target material is bombarded and pre-sputtered for 2-5 minutes. During this period, the substrate is shielded with a baffle to clean the target surface, remove the oxide layer and contaminants, and stabilize the sputtering rate and film composition. Step A2. Formal Deposition: Remove the baffle and maintain stable Ar gas flow, pressure, and power. The substrate is usually not biased or is subjected to a very low bias (<20V) to avoid excessive ion bombardment that could lead to rough metal film or excessive stress. The deposition rate and film thickness are monitored in real time using a quartz crystal film thickness monitor. The deposition rate is 0.5-3nm / s. When the film thickness monitor detects that the set value has been reached, the target power supply is automatically turned off and the baffle is moved back, and the deposition ends.

[0025] Preferably, the preparation process of the basic reflective layer of the metal oxide material is as follows: Step B1. Establish a stable process point: First, introduce Ar (99.99% purity) at a flow rate of 40 sccm, adjust the pressure to 0.3-0.5 Pa, and turn on the power supply of Ti target, Si target or Nb target (all with 99.99% purity) at a power density of 3-5 W / cm2. O2 (99.99% purity) is slowly introduced, and the flow rate is gradually increased from 0 in increments of 1-5 sccm. The changes in target voltage and deposition rate are observed simultaneously. As O2 increases, the target surface gradually oxidizes, leading to an increase in target voltage and a sharp decrease in deposition rate until the deposition rate stabilizes (set at the leading edge of the rate-oxygen flow rate curve; this point usually requires a closed-loop active control system to automatically adjust the O2 flow rate by monitoring the intensity of specific spectral lines (such as Ti atomic lines) in the plasma emission spectrum). Step B2. Formal Deposition: After the process stabilizes, the baffle is removed, and the Ar flow rate is controlled at 40 sccm and the O2 flow rate at 8 sccm. An RF substrate bias voltage (power density 50-150 W / m2) is applied. This is crucial for oxide thin films, as the bias voltage attracts ions to bombard the growing film, making it denser and smoother, and improving optical properties (increasing refractive index and reducing absorption). The working pressure is 0.4 Pa, the power density is 4 W / cm2, and the substrate bias voltage is: RF, 13.56 MHz, power density 100 W / m2. The deposition rate is 0.1-1.0 nm / s, and the endpoint is controlled by a film thickness monitor to obtain a single layer of high-refractive-index material or low-refractive-index material. Step B3. Alternating deposition: The substrate will be transferred to the next process chamber containing different targets (e.g., if the upper layer is TiO2, this layer can be set as a Si target). Step B2 is repeated to deposit low-refractive-index material layers or high-refractive-index material layers in sequence. After all thin films are deposited, the substrate is transferred back to the sample chamber, high-purity nitrogen is introduced into the sample chamber to atmospheric pressure, and the sample is taken out to obtain the base reflective layer with alternating deposition of high-refractive-index material layers and low-refractive-index material layers.

[0026] Preferably, step S2 uses slot coating or spin coating to uniformly coat the photocurable resin solution (negative film) onto the surface of the reflective layer, and then bakes it in an oven at 70-90°C for 1-2 minutes to remove most of the solvent, forming a resin layer with a dry film thickness of about 3-8 μm.

[0027] Furthermore, the photocurable resin solution comprises the following components by weight percentage: 40%-55% Bisphenol A type epoxy acrylate prepolymer or aliphatic polyurethane acrylate: The two can be used in combination to balance performance, serving as the main body for film formation and determining the basic mechanical and chemical properties of the cured film. 35%-50% reactive diluent: to adjust the viscosity and reactivity of the system. The reactive diluent is any of the following: trimethylolpropane triacrylate (TMPTA) (high crosslinking degree, improves chemical resistance), dipentaerythritol hexaacrylate (DPHA) (extremely high functionality, used for high hardness requirements), and neopentyl glycol diacrylate (NPG(PO)2DA) (reduces shrinkage and improves adhesion). 4%-8% photoinitiator: absorbs ultraviolet light to generate free radicals and initiate polymerization. The photoinitiator is a compound of 1-hydroxycyclohexylphenyl ketone (Irgacure184) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO) in a weight ratio of 1:0.2-0.3. Irgacure184 provides surface curing, and TPO, as a long-wavelength absorber, provides a deeper curing depth and a faster curing speed. 0.3%-1.5% of γ-(methacryloyloxy)propyltrimethoxysilane (KH-570) is an adhesion promoter. Its siloxane end can form a strong chemical bond with the surface of metal or metal oxide, and the acrylate end participates in the photocuring reaction, which greatly enhances the bonding force between the resin in the cured area and the reflective layer, preventing peeling or drilling in the subsequent etching solution. 0.1%-0.5% of polyether-modified polydimethylsiloxane (such as BYK-333): This is a leveling agent that can effectively reduce the surface tension of the resin liquid, eliminate defects such as orange peel and pinholes that may occur during the coating process, and obtain an extremely smooth film layer. This is the basis for ensuring the uniformity of the exposure pattern. 0.1%-0.3% of non-silicone polymer defoamer (such as BYK-055) can suppress the generation and retention of bubbles during high-speed coating, thus avoiding the formation of film defects. 0.2%-0.5% of p-methoxyphenol (MEHQ) or 2,6-di-tert-butyl-p-cresol (BHT): as a stabilizer, especially as a thermal polymerization inhibitor, to improve the stability of the resin solution during storage and pre-baking.

[0028] Preferably, step S3 uses an exposure machine equipped with a high-pressure mercury lamp or a 365nm LED surface light source. A photomask (mask) with a designed target pattern (a random grid with a linewidth of 3-10μm or a pixel array with gradually varying sizes) is brought into close contact with the sample coated with a resin layer. Depending on the film thickness and formulation, the exposure energy is 200-600mJ / cm², and the exposure time is calculated using the following formula:

[0029] After exposure, the resin in the corresponding area of ​​the pattern undergoes cross-linking and curing (negative process), resulting in significant differences in solubility and chemical resistance compared to the unexposed area.

[0030] Preferably, step S4 involves processing different reflective layer materials separately: Path 1. The reflective layer material is a metallic material: The uncured area and the light-transmitting area below it are removed simultaneously by immersion in the treatment solution; For the aluminum reflective layer: Take 10g of sodium hydroxide and 5g of sodium gluconate, dissolve them in 800mL of deionized water, stir to dissolve, add 150mL of N-methylpyrrolidone (NMP), and finally add 1mL of Triton X-100. Stir evenly and adjust the volume to 1L. Control the working temperature at 45±5℃ to obtain the aluminum treatment solution. Immerse the exposed sample in the aluminum treatment solution and etch for 1-5 minutes. The resin in the uncured area is rapidly swollen and dissolved, and the exposed metal is then attacked and removed by the etching solution. In the cured area, because the resin has formed a dense cross-linked network and the KH-570 adhesion promoter enhances the interfacial bonding, it can effectively resist the penetration and attack of the treatment solution and protect the underlying metal from being etched. Then clean and dry. For the copper reflective layer: Take 150g of copper chloride, dissolve it in about 600mL of deionized water, slowly add 100mL of concentrated hydrochloric acid, then add 50mL of phosphoric acid, stir and cool, then add 80mL of dimethyl sulfoxide (DMSO) and bring the volume to 1L. Control the working temperature at 40±5℃ to obtain the copper treatment solution; immerse the exposed sample in the copper treatment solution, etch for 1-5 minutes, then clean and dry. Path 2. The reflective layer material is a metal oxide material: The uncured area and the light-transmitting area below it are removed sequentially by plasma. Step S4a. Oxygen plasma removes non-curable resin: The sample is placed in a reactive ion etching (RIE) or plasma ashing apparatus, oxygen (O2) is introduced at a flow rate of 80 sccm, the chamber pressure is 1.0 Pa, an RF power of 300 W is applied, and the processing time is 90-180 seconds. Under these conditions, uncured organic matter is efficiently ashed and removed, exposing the underlying oxide reflective layer; the resin in the cured area is also partially thinned, but due to its cross-linked structure, the etching rate is slow, and the mask function is still maintained. The high-functionality diluent (such as DPHA) and adhesion promoter (KH-570) in the formulation ensure the structural integrity of the cured film and its firm adhesion to the substrate in the plasma environment during this step, preventing wrinkling or peeling.

[0031] Step S4b: Reactive ion etching (RIE) of the oxide reflective layer: By continuously changing the etching gas in the same equipment, the light-transmitting areas of the high-refractive-index material layer and the low-refractive-index material layer are removed sequentially. For the SiO2 layer: use a mixed gas of CF4 (40 sccm) and O2 (10 sccm), pressure 0.5 Pa, power 400 W, etch to the endpoint; For TiO2 or Nb2O5 layers: use a mixed gas of Cl2 (30 sccm) and BCl3 (20 sccm), pressure 0.8 Pa, power 350 W, etch to the endpoint; After etching, the surface is cleaned briefly with Ar gas.

[0032] Preferably, S5 includes the following process: After S4, the patterned reflective structure has been formed, but the surface is still covered with a cured resin layer. The sample is immersed in N-methylpyrrolidone (NMP) heated to 60°C or a special stripping solution, and then subjected to ultrasonic treatment at a power of 50W for 3-8 minutes until the cured resin is completely swollen and detached. Finally, the sample is washed with isopropanol and deionized water in sequence, and then dried with nitrogen to obtain a patterned reflective film product with a clean surface and clear pattern.

[0033] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention patterns a continuous metal layer into discrete reflective units, with the unit spacing (i.e., the linewidth of the transparent region) designed to be 3-10 μm. This size is much smaller than microwave wavelengths (centimeter-scale) but much larger than visible light wavelengths (submicron-scale). According to electromagnetic theory, when the structure size is much smaller than the wavelength, electromagnetic waves will treat it as an effective medium rather than a discrete structure. For microwaves (λ ~ 3-10 cm), the 3-10 μm gap is equivalent to an unobstructed channel, and microwaves mainly pass through through capacitive coupling (forming capacitive paths between adjacent metal units) and direct penetration. For visible light (λ = 380-780 nm), although the 3-10 μm gap causes some light scattering, most of the light is still reflected by the metal units because the size of the metal units (typically > 5 μm) is much larger than the wavelength of light, exhibiting optical properties similar to continuous metals, thus resolving the contradiction between high reflectivity and high transmittance.

[0034] 2. Moiré patterns are spatial interference fringes produced when two sets of regular patterns (such as a reflective film grid and a display screen pixel array) are superimposed. Their visibility and intensity depend on the spatial frequency difference and relative angle between the two patterns. This invention uses a random grid or a gradually changing aperiodic array to break the spatial periodicity of the reflective pattern, fundamentally eliminating moiré patterns. Mathematically, its spatial spectrum is a continuous spectrum, not the discrete spectral lines of a periodic pattern. Therefore, superimposing it with any regular display pixels will not produce obvious, stable interference fringes.

[0035] 3. In integrated antenna devices, the signal strength is strongest near the antenna, requiring the highest transmittance; while areas farther from the antenna have lower signal requirements but higher requirements for decorative reflectivity. This invention proposes a gradient pixel array, where the density of reflective elements gradually changes with distance from the antenna. In the near-antenna region, the reflective density is as low as 30% (70% transmittance), prioritizing signal strength; in the far-antenna region, the density is as high as 80%, prioritizing reflectivity. The intermediate transition zone achieves a smooth gradient, optimizing both signal transmission and visual uniformity.

[0036] 4. This invention generates a 20-150nm compound layer (Cu3N, Cu2O, CuO, etc.) on the surface of a copper reflective layer through plasma oxidation / nitriding. The thickness of this thin film is comparable to the wavelength of visible light, producing thin film interference colors (blue, red). Because its thickness is only one-thousandth of the microwave wavelength, it is almost transparent to microwaves. Furthermore, by precisely controlling the O2 / N2 ratio, power, and time in the plasma, the chemical phase and thickness of the generated compound can be adjusted, thereby achieving continuous color control from blue, red, bronze to pure black, providing rich decorative colors without affecting microwave performance.

[0037] 5. This invention adds KH-570 silane coupling agent to the photoresist formulation. Its siloxane end forms a strong chemical bond (Si-OM) with the metal / oxide surface, and the acrylate end participates in photocuring crosslinking, which greatly improves the bonding force between the cured resin and the reflective layer and prevents drilling during etching. In addition, the substrate is made of 30-100μm PET or PI. Combined with an appropriate reflective layer thickness (480-3000nm) and pattern design, the film has excellent flexibility. The product can withstand more than 100,000 bending tests and meets the requirements of foldable devices.

[0038] 6. The present invention can also use TiO2 / SiO2 quarter-wavelength film stacks to achieve extremely high reflectivity (>98%) at a specific wavelength (e.g., 550nm) through optical interference. Compared with metals, the dielectric material has stable chemical properties, is resistant to oxidation and corrosion, and has stable performance in high temperature and high humidity environments (tests show ΔR < 1.2%). Moreover, the dielectric film stack can still maintain a transmittance of 76.5%, which is much higher than that of continuous metals.

[0039] 7. In summary, this invention, through innovative patterning design, material selection, and process control, achieves for the first time a synergistic effect of high optical reflectivity and low electromagnetic shielding on a single thin film, breaking through the long-standing technical bottleneck restricting the application of metal decorative films in wireless devices. Its core lies in utilizing the significant wavelength difference between microwaves and visible light (approximately 104 times), using precisely defined micron-level patterns to differentiate between the two electromagnetic wave bands. This results in high fabrication yield and process controllability, and its products can be widely used in 5G mobile phones, automotive equipment, high-end home appliances, AR / VR, and various wearable devices. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the stacked structure of the reflective film obtained in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the stacked structure of the reflective film obtained in Embodiment 3 of the present invention; Figure 3 This is a schematic diagram of the stacked structure of the reflective film obtained in Embodiment 5 of the present invention; Figure 4This is a process flow diagram of the reflective film of the present invention; Figure 5 This is a schematic diagram of the microstructure of the reflective film obtained in Embodiment 1 of the present invention; Figure 6 This is a 150x microscope image of the reflective film obtained in Example 2 of the present invention; Figure 7 This is a schematic diagram illustrating the visual uniformity effect of the reflective film obtained in Embodiment 2 of the present invention; Figure 8 This is a 150x microscope image of the reflective film obtained in Example 3 of the present invention; Figure 9 This is a schematic diagram of the grid structure design in Embodiment 4 of the present invention; Figure 10 This is a schematic diagram of the photomask 3 used in Embodiment 4 of the present invention; Figure 11 This is a 150x magnified micrograph of the reflective film obtained in Example 4 of the present invention. Figure 12 This is a schematic diagram of the design of the near-antenna region (region A) in Embodiment 5 of the present invention; Figure 13 This is a schematic diagram of the design of the far-field antenna region (region B) in Embodiment 5 of the present invention; Figure 14 This is a schematic diagram illustrating the visual uniformity effect of the reflective film obtained in Embodiment 5 of the present invention; Figure 15 This is a 150x microscope image of the reflective film obtained in Example 5 of the present invention.

[0041] In the diagram: 1: Substrate layer; 1A: PET protective film; 2: Reflective layer; 2A: CPP protective film; 2B: Blackening layer; 2C: Reflective unit; 2D: Transmitting area; 201: High refractive index material layer; 202: Low refractive index material layer; 3: Photomask; 301: Blocking area; 302: Cutout area; 4: Photocurable resin layer; 401: Cured area; 402: Uncured area. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0043] Example 1. Copper-based random grid reflective film (standard parameters), process referenced. Figure 4 : 1. Substrate preparation: Step 1.1: Take a 75μm thick PET roll (600mm wide), and clean it for 5 minutes in an ultrasonic cleaner with a solution of anhydrous ethanol and acetone mixed in a 1:1 volume ratio.

[0044] Step 1.2: Place the cleaned PET into a vacuum plasma cleaner, evacuate to 5×10-3Pa, introduce Ar gas (purity 99.999%) to a pressure of 5Pa, apply radio frequency power of 300W, and process for 90 seconds.

[0045] Step 1.3: Measure the surface tension of the treated PET with a surface energy tester to confirm that it reaches 42mN / m or higher.

[0046] 2. Sputter deposition of copper reflective layer: Step 2.1: Load the treated PET substrate into the sample inlet chamber of the magnetron sputtering equipment and evacuate to 1×10-4 Pa.

[0047] Step 2.2: Transfer to process chamber 1 (install pure copper target material, purity 99.99%, size 400×120mm).

[0048] Step 2.3: Pre-sputtering: Introduce Ar gas (99.999%) at a flow rate of 50 sccm. Adjust the gate valve to stabilize the chamber pressure at 0.5 Pa. Turn on the DC power supply and gradually increase the power density from 0 to 4 W / cm2 (total power 2 kW). Use a baffle to shield the substrate. Pre-sputter for 3 minutes. Monitor the target voltage to stabilize at 380 V ± 5 V and the sputtering current to stabilize at 5.26 A. Step 2.4: Formal Deposition: Remove the baffle, maintain Ar gas flow rate of 50 sccm, pressure of 0.5 Pa, power density of 4 W / cm2, no bias voltage applied to the substrate, and a transfer speed of 0.5 m / min. Use a quartz crystal film thickness monitor (Inficon SQM-160) for real-time monitoring. Deposition rate: 1.5 nm / s. Deposition time calculation: 1200 nm ÷ 1.5 nm / s = 800 seconds = 13 minutes and 20 seconds. When the set thickness is reached, automatically turn off the target power supply. After the chamber cools for 5 minutes, remove the sample. Step 2.5: Film thickness verification: Five points were measured using a Bruker Dektak XT profilometer. The thicknesses were 1202nm, 1198nm, 1205nm, 1195nm, and 1201nm, with an average of 1200.2nm and a standard deviation of 3.8nm.

[0049] 3. Photoresist coating: Step 3.1: Preparation of the photocurable resin solution (weight percentage): Bisphenol A epoxy acrylate prepolymer (Changxing Chemical 6311-100): 48%; TMPTA (trimethylolpropane triacrylate): 40%; Photoinitiator: Irgacure 184 4.0% + TPO 1.5% (total 5.5%); KH-570 (γ-(methacryloyloxy)propyltrimethoxysilane): 0.8%; BYK-333 leveling agent: 0.3%; BYK-055 defoamer: 0.2%; BHT stabilizer: 0.2%; Step 3.2: Apply coating using a slot coater (Yasui Seiki): coating head gap: 80μm, substrate transfer speed: 2m / min, resin supply speed: 50mL / min, coating temperature: 25℃; Step 3.3: Pre-baking: Place in an oven, 80℃ hot air circulation, baking time: 90 seconds; Dry film thickness measurement: Use Filmetrics F20 to measure 5 points, the thicknesses are 4.95μm, 5.02μm, 4.98μm, 5.05μm, 4.97μm, with an average of 4.99μm; 4. Exposure: Step 4.1: Prepare the photomask: Material: quartz glass chrome-plated mask, pattern: random grid pattern, line width design value of 6μm, light transmission area ratio: 55%, pattern size: 600×600mm; Step 4.2: Contact Exposure: Equipment: ORC662GS Exposure Machine (High-Pressure Mercury Lamp), Light Source Wavelength: 365nm (i-line), Light Intensity: 25mW / cm2 (measured using a radiometer), Exposure Energy Calculation: 400mJ / cm2 ÷ 25mW / cm2 = 16 seconds, Actual Exposure Time: 16 seconds, Vacuum Adsorption Pressure: -80kPa to ensure tight contact; 5. Development (removal of uncured areas): Step 5.1: Prepare alkaline developer: 2.38% tetramethylammonium hydroxide (TMAH) aqueous solution, temperature control: 25±1℃, development time: 60 seconds; Step 5.2: Development operation: Spray pressure: 0.2MPa; Post-development inspection: Confirm complete removal of uncured resin under an optical microscope; Line width measurement: Randomly measure 10 locations, with line widths of 6.1μm, 6.3μm, 5.9μm, 6.2μm, 6.0μm, 6.2μm, 5.8μm, 6.1μm, 6.0μm, and 6.2μm, with an average of 6.08μm. 6. Copper etching: Step 6.1: Prepare copper etching solution: Copper chloride (CuCl2·2H2O): 150g, deionized water: 600mL, concentrated hydrochloric acid (37%): 100mL (added slowly), phosphoric acid (85%): 50mL, dimethyl sulfoxide (DMSO): 80mL; add deionized water to a final volume of 1000mL, temperature control: 40±0.5℃ water bath; Step 6.2: Etching operation: Immerse the sample completely in the etching solution. Etching time: 180 seconds, gently shake every 30 seconds. Etching endpoint judgment: The copper layer in the light-transmitting area is completely removed (it becomes transparent to the naked eye). Step 6.3: Cleaning: Spray with deionized water for 30 seconds, soak in 1% dilute hydrochloric acid for 15 seconds (to neutralize residual alkali), ultrasonically clean with deionized water (40kHz, 100W) for 2 minutes, and blow dry with nitrogen (pressure 0.3MPa). 7. Remove glue: Step 7.1: Prepare the adhesive remover: N-methylpyrrolidone (NMP): 100%, temperature: 60±2℃; Step 7.2: Resin removal: Immersion time: 5 minutes, ultrasonic assistance: 50W, 40kHz, confirm complete removal of cured resin under a microscope; Step 7.3: Final cleaning: Isopropanol cleaning: 2 minutes; Deionized water rinsing: 1 minute; Centrifugal drying: 2000 rpm, 2 minutes; Vacuum drying: 60℃, 30 minutes; The resulting reflective film stack structure is as follows Figure 1 As shown, the substrate layer 1 is covered with a PET protective film 1A, and the reflective layer 2 is covered with a CPP protective film 2A. The material of the protective film is not limited to any type of polymer. In this process, below the cutout area 302 of the photomask 3, there is a cured area 401 of the photocurable resin layer 4, which is protected by photocuring. The uncured area 402 and the light-transmitting area 2D below the masking area 301 are sequentially etched away. Finally, the cured area 401 is removed, leaving only the reflective unit 2C, thus obtaining the desired result. Figure 5 The reflective film shown.

[0050] 8. Performance Testing: Reflectivity test: Using a Perkin Elmer Lambda1050+ integrating sphere, the reflectivity at 550nm was 89.7%; Transmittance test: Keysight N5227B network analyzer + horn antenna, 3.5GHz transmittance 93.8%; Surface resistance: 0.08Ω / sq with four probes.

[0051] Example 2. Aluminum-based gradient pixel array: The only difference from Example 1 is in the following steps: 1. Substrate treatment: Step 1.1: 100μm thick PI film (DuPont Kapton) UV ozone cleaning: Equipment: UVOCST10X10, wavelength: 185nm+254nm, irradiation distance: 10mm, time: 300 seconds, surface energy: increased from 38mN / m to 52mN / m; 2. Aluminum layer sputtering: Step 2.1: Pure aluminum target (99.999%), size 400×120mm; Step 2.2: Deposition parameters: Ar gas: 60 sccm, pressure: 0.4 Pa, power density: 5 W / cm2 (total power 2.5 kW), substrate bias: -20 VDC, deposition rate: 2.2 nm / s, deposition time: 2500 nm ÷ 2.2 nm / s = 1136 seconds ≈ 18 minutes and 56 seconds, actual thickness measurement: 2512 nm, 2503 nm, 2498 nm, 2510 nm, 2505 nm, average 2505.6 nm; 3. Gradient mask design and fabrication: Step 3.1: Design the gradient pattern using CAD software: Pixel size: 8×8μm; Near antenna area (100×100mm): pixel pitch 20μm, light transmittance 85%; Far antenna area (100×100mm): pixel pitch 8μm, light transmittance 25%; Intermediate transition area (200×100mm): linear gradient; Total area: 400×100mm; Step 3.2: Electron beam mask fabrication: Equipment: JEOLJBX-9500FS, writing accuracy: 5nm, actual linewidth: 8.0±0.1μm; 4. Photolithography process: Step 4.1: Coating thickness: 6μm (baking at 80℃ for 100 seconds); Step 4.2: Exposure: Zoned exposure, energy 450mJ / cm2; Step 4.3: Development: TMAH 2.38%, 70 seconds; 5. Aluminum etching: Step 5.1: Preparation of etching solution: Sodium hydroxide: 10g, sodium gluconate: 5g, deionized water: 800mL, N-methylpyrrolidone: 150mL, Triton X-100: 1mL; adjust the volume to 1000mL, temperature: 45±0.5℃; Step 5.2: Etching time: 240 seconds, with samples taken for microscopic examination every 30 seconds; this process yields the following results. Figure 6 The reflective film shown (150x microscope) has the following visual effect: Figure 7 As shown.

[0052] Example 3. TiO2 / SiO2 quarter-wavelength film stack: The only difference from Example 1 is in the following steps: 1. TiO2 layer deposition: Step 1.1: Titanium target (99.99%), reactive sputtering: Ar gas: 40 sccm, O2 gas: 8 sccm, pressure: 0.4 Pa, power density: 4 W / cm2, substrate bias: RF, 100 W / m2, 13.56 MHz, deposition rate: 0.25 nm / s; Step 1.2: Thickness control: Target thickness: 58.5nm (λ0 / 4n, λ0=550nm, n=2.35), deposition time: 58.5÷0.25=234 seconds, actual thickness: 58.7nm, 58.3nm, 58.9nm, average 58.6nm; 2. SiO2 layer deposition: Step 2.1: Silicon target (99.99%), reactive sputtering: Ar gas: 40 sccm, O2 gas: 10 sccm, pressure: 0.4 Pa, power density: 4 W / cm2, substrate bias: RF, 100 W / m2, deposition rate: 0.18 nm / s; Step 2.2: Thickness control: Target thickness: 94.2nm (λ0 / 4n, n=1.46), deposition time: 94.2÷0.18=523 seconds, actual thickness: 94.5nm, 94.0nm, 94.3nm, average 94.3nm; 3. Repeated deposition: Step 3.1: 6 pairs of alternating depositions, for a total of 12 layers: TiO2 / SiO2 / TiO2 / SiO2 / TiO2 / SiO2 / TiO2 / SiO2 / TiO2 / SiO2 / TiO2 / SiO2, with a total thickness of 58.6×6+94.3×6=917.4nm; 4. Photolithography and etching: Step 4.1: Resin coating: 5μm, baked at 85℃ for 110 seconds; Step 4.2: Exposure: Regular grid, linewidth 10μm, energy 500mJ / cm2; Step 4.3: Oxygen plasma degumming: Equipment: Oxford Plasmalab100, O2 flow rate: 80 sccm, pressure: 1.0 Pa, RF power: 300 W, time: 150 seconds; Step 4.4: SiO2 layer etching: Gas: CF4 40 sccm + O2 10 sccm, Pressure: 0.5 Pa, RF power: 400 W, Etching rate: 60 nm / min, Time: 94.3 nm ÷ 60 nm / min ≈ 1 minute 34 seconds; Step 4.5: TiO2 layer etching: Gas: Cl2 30 sccm + BCl3 20 sccm, Pressure: 0.8 Pa, RF power: 350 W, Etching rate: 45 nm / min, Time: 58.6 nm ÷ 45 nm / min ≈ 1 minute 18 seconds; Step 4.6: Etch 6 pairs layer by layer, with a total etching time of approximately 18 minutes.

[0053] The resulting reflective film stack structure is as follows Figure 2 As shown, the substrate layer 1 is covered with a PET protective film 1A, and the reflective layer 2 is composed of a high refractive index material layer 201 and a low refractive index material layer 202 stacked together; the microstructure is as follows. Figure 8 As shown (magnification 150x).

[0054] Example 4. Copper-based fine-line mesh (minimum line width): The only difference from Example 1 is in the following steps: 1. Thin copper layer deposition: Step 1.1: Thickness 480nm, deposition rate: 1.2nm / s, deposition time: 480÷1.2=400 seconds, actual thickness: 482nm, 479nm, 481nm, average 480.7nm; 2. Fine-grained patterned photomask: Step 2.1: Random mesh design: line width: 3.0μm (lower limit), light transmittance: 70%, manufacturing accuracy requirement: ±0.1μm; 3. High-precision photolithography: Step 3.1: Thin film process: Resin thickness: 3μm (baked at 70℃ for 80 seconds), exposure energy: 300mJ / cm2 (reduce energy to reduce scattering), development: TMAH 2.38%, 45 seconds (shorten the time); 4. Precision etching: Step 4.1: Etching solution optimization: Add the following to the original formula: Citric acid: 5g / L (to improve side etching control), benzotriazole: 0.5g / L (edge ​​protectant). Step 4.2: Etching conditions: Temperature: 38℃ (slightly lower than Example 1), Time: 120 seconds, Stirring: Magnetic stirring, 200 rpm; 5. Blackened layer: Step 5.1: Two-step blackening method: Step 1: Total pressure: 1.0 Pa, Ar gas: 40 sccm, N2 gas: 20 sccm, O2 gas: 50 sccm, power density: 2.0 W / cm2, time: 120 seconds; Step 2: Pure O2: 60 sccm, power density: 2.5 W / cm2, time: 60 seconds; Step 5.2: Thickness measurement: 120nm, 118nm, 122nm, average 120nm.

[0055] The resulting reflective film's grid structure design is as follows: Figure 9 As shown (where the black area is the reflective unit 2C), the photomask 3 used is as follows: Figure 10 As shown (where the black line represents the occlusion area 301), the actual microstructure is as follows. Figure 11 As shown.

[0056] Example 5: Composite Pattern Optimization The only difference from Example 1 is in the following steps: 1. Aluminum layer deposition: Step 1.1: Thickness 1800nm, deposition rate: 2.0nm / s, time: 900 seconds; 2. Composite photomask design: Step 2.1: Main pattern: gradient pixel array, density gradient: 30%-90%, pixel size: 10×10μm; Step 2.2: Supplement the pattern: Apply only to dense areas (density > 70%), random grid, line width 5μm, increase light transmittance by 15%; 3. Double exposure process: Step 3.1: First exposure: main pattern, energy: 400mJ / cm2, main mask: gradient pixel array; Step 3.2: Second exposure: supplement the pattern, energy: 350mJ / cm2, sub-mask: random grid (only covering dense areas), alignment accuracy: ±2μm; Step 3.3: Combined development: TMAH 2.38%, 85 seconds, development rate of the overlapping area of ​​the two patterns increased by 20%; 4. Etching: Step 4.1: Aluminum etching solution, 45°C, 210 seconds.

[0057] The resulting laminated structure of the reflective film is as follows Figure 3 As shown, the surface of reflective layer 2 also has a blackening layer, the microstructure of which is as follows: Figure 15 As shown (magnification 150x).

[0058] Based on the gradient pixel pattern of Example 2, a random grid pattern from Example 1 is further introduced as a secondary light-transmitting channel in dense areas with a reflectance density greater than 70%. That is, a gradient pixel pattern is first prepared, and then random grid lines are etched and superimposed in the local high-density areas. This design maximizes the preservation of the high-reflectance visual integrity of the film surface while ensuring optimal signal penetration in key areas.

[0059] Specifically, the patterning employs a main photomask (for the entire area) and a secondary photomask (for densely populated areas) with gradient pixel patterns, and the reflective elements are square reflective dots measuring 8μm × 8μm. During the design process, the entire membrane surface is divided into different regions: region A, located near the preset antenna position, is designed as follows... Figure 12 As shown, the reflection point density is set to 30% (i.e., the light-transmitting area occupies 70%), and the design of area B, which is far from the antenna position, is as follows. Figure 13 As shown, the reflective dot density is set to 80%. The overall visual effect of the reflective film is as follows. Figure 14 As shown, areas A and B are connected by a region with a smooth density transition, resulting in a reflective film that is visually uniform macroscopically and has wave-transmitting channels with varying density microscopically, effectively avoiding signal interference. After being processed using a specific bending process (refer to the conductive film, metal mesh touchscreen sensor, touch module, and its fabrication method in patent publication number CN120600377 A), this film can withstand more than 100,000 bending tests.

[0060] Comparative Example 1. Unpatterned continuous reflective film (copper): The following differences are observed compared to Example 1: Substrate layer: 50 μm PET; Reflective layer thickness: 800 nm; Pattern type: None (continuous film); Blackening treatment: None. Clearly, it cannot be used in signal transmission areas.

[0061] Comparative Example 2. Regular mesh (copper, linewidth 15μm): The following differences were observed compared to Example 1: Substrate layer: 50 μm PET; Reflective layer thickness: 800 nm; Pattern type: Regular square grid, line width 15 μm; Blackening treatment: None. Results: Moiré pattern assessment: Severe interference fringes (observation distance 30 cm); Visual visibility: Grid clearly visible (distinguished to the naked eye); Signal transmission uniformity: Periodic fluctuation ±15%.

[0062] Comparative Example 3. Random grid, but linewidth too narrow (1μm): The differences from Example 1 are as follows: substrate layer: 50μm PET; reflective layer thickness: 800nm; pattern type: random grid, line width 1μm, insufficient etching precision leading to partial line breaks, pattern defect rate: 18.3% (partial light-transmitting areas were not completely etched), signal shielding residue: local shielding areas caused signal shadows, and the preparation yield was <70%.

[0063] Comparative Example 4. Gradient array but without adhesion promoter: The preparation process is the same as in Example 2, but the resin formulation does not contain KH-570. Severe etching occurs during etching, with the pattern edge roughness being ±2.1μm (target ±0.5μm), the minimum line width being only >8μm, adhesion being grade 2B (partial peeling), etching uniformity being ±25%, and yield being <60%.

[0064] Comparative Example 5: Quarter-wavelength film stack with a thickness deviation of 20% Same as Example 3, but with a film thickness control deviation of ±20%. Theoretical thickness: TiO2 61nm, actual 73nm; SiO2 94nm, actual 113nm.

[0065] The product performance of Examples 1-5 and Comparative Examples 1-5 is shown in Table 1 below: Table 1. Performance Tests of Different Reflective Films

[0066] Based on Table 1 and related graphical analysis, the following conclusions can be drawn: 1. Physical mechanisms of reflection and signal shielding: The continuous metal film in Comparative Example 1 forms a complete conductive path, generating surface reflection and internal eddy current absorption of electromagnetic waves, with a shielding effectiveness (SE) > 45dB, satisfying the formula: SE = 50 + 10log(ρf) - 1 + 1.7t(f / ρ) 1 / 2 (t is the thickness, ρ is the resistivity, and f is the frequency).

[0067] In Examples 1-5, a patterned metal layer is used, and the current continuity is interrupted in the light-transmitting area. The signal penetration is mainly through: ① capacitive coupling (between adjacent reflective units); ② direct penetration (linewidth < λ / 10, 3-10μm is much smaller than the signal wavelength 3-10cm).

[0068] In Example 3, the dielectric film stack enhances reflection through interference, but there are no free electrons. The signal penetration is affected by the dielectric constant: transmittance ∝(εr)-1 / 2, εr≈3.9 for SiO2, which is better than εr→∞ for metals.

[0069] 2. The effect of thickness range (480-3000nm): Lower limit 480nm: As demonstrated in Example 4, copper has a skin depth δ≈25nm at 550nm and a thickness of 480nm (≈19δ) to ensure that volume reflection is dominant and surface roughness has an effect of <2%.

[0070] Upper limit 3000nm: Exceeding 3000nm increases cost without significantly improving reflectivity (copper reaches 99.5% saturation reflectivity at 2000nm).

[0071] For example, the 300nm film thickness in Comparative Example 3 is only ≈12δ, resulting in partial light transmission and insufficient reflectivity.

[0072] 3. Optimization and balance of linewidth range (3-10μm) Lower limit 3μm: close to the current limit of photolithography etching process, ensuring yield >90%; providing sufficient signal channels (3μm corresponds to a 100GHz cutoff frequency, which is much higher than the communication frequency band).

[0073] Upper limit 10μm: below the human eye resolution limit (10-12μm), ensuring it is invisible to the naked eye; avoiding significant interference with common display pixels (10-100μm).

[0074] For example, the 15μm linewidth in Comparative Example 2 is visible to the naked eye and may produce low-frequency moiré patterns with the display pixels.

[0075] 4. Signal optimization for gradient design: In Example 2, the light-transmitting area ratio gradually changes from 85% to 25%, and the signal insertion loss increases from 0.5dB to 1.8dB, achieving near-field optimization of the antenna.

[0076] 数学模型：透波率T(x)=T0+(T1-T0)·exp(-αx)，x为距天线距离，α为衰减系数，渐变设计匹配该规律。

[0077] 5. Optical and signal effects of the blackening layer In Example 4, the 120nm black copper oxide layer reduced the reflectivity from 89% (the natural color of copper) to 45.8%, but had minimal impact on the signal (transmittance decreased by only 1.3%). The blackening layer thickness was 20-150nm << the signal wavelength (30000nm), making it nearly transparent to microwaves; however, it interfered with visible light interference and reduced reflection.

[0078] 6. Recommended application scenarios: 5G mobile phone back cover decoration: Example 1 (89.7% reflection, 93.8% transmittance) balances appearance and signal.

[0079] Vehicle antenna area decoration: Example 2 (gradient design) to match the antenna near-field requirements.

[0080] High-end home appliance panel: Example 3 (98.2% high reflectivity) meets decoration requirements and has low signal requirements.

[0081] AR / VR Devices: Example 4 (Low Reflection Anti-Glare) Reduces Ambient Light Interference.

[0082] Smartwatch: Example 5 (Composite Optimization) Balancing Multiple Antenna Requirements in a Small Space

[0083] 7. Summary: The patterned reflective film of this invention successfully solves the contradiction between high reflectivity and low signal shielding: the 480-3000nm reflective layer thickness ensures reflectivity (45-98%) while controlling costs; the 3-10μm transmittance width enables effective signal penetration (transmittance 76-98%) and is invisible to the naked eye; the patterned design (random / gradient / composite) avoids moiré patterns and improves visual uniformity; the dielectric film stack provides the highest reflectivity (>98%) but has low signal transmittance (approximately 77%); the blackening layer can adjust the appearance (black / blue / red) with minimal impact on the signal.

[0084] Comparative Examples 1-5 demonstrate that continuous films, excessively wide linewidths, insufficient thickness, and regular arrays can lead to complete signal shielding, visually visible defects, insufficient reflection, or moiré patterns. This invention achieves an optimal balance between reflection and transmission through precise parameter range control.

[0085] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A patterned reflective film, comprising a substrate layer (1) and a reflective layer (2) formed on the substrate layer, characterized in that, The thickness of the substrate layer (1) is 30-100μm; the material of the reflective layer (2) is a metal material or a metal oxide, and the thickness of the reflective layer (2) is 480nm-3000nm; The reflective layer (2) is patterned to form a discontinuous reflective pattern, which includes reflective units (2C) separated by light-transmitting regions (2D), the linewidth of which is 3-10 micrometers, so that electromagnetic waves can effectively penetrate the reflective film.

2. The patterned reflective film according to claim 1, characterized in that, The substrate layer (1) is polyethylene terephthalate or polyimide film material, and the polymer with a thickness of 30-100μm gives the reflective film good bending resistance.

3. The patterned reflective film according to claim 1, characterized in that, The material of the reflective layer (2) is a copper or aluminum metal or a metal oxide with a certain reflectivity, and the metal oxide includes TiO2, SiO2 or Nb2O5.

4. The patterned reflective film according to claim 1, characterized in that, The reflective pattern is a random grid pattern, and the light-transmitting area (2D) consists of randomly distributed grid lines with a line width of 3-10 micrometers.

5. A patterned reflective film according to claim 1, characterized in that, The reflective pattern is a gradient pixel array, and the reflective unit (2C) is a discrete reflective point with a size in the micrometer range. The distribution density of the reflective points is gradually designed according to the distance of their respective areas from the signal antenna: the closer the area is to the antenna, the sparser the distribution of reflective points and the larger the proportion of the light-transmitting area; the farther the area is from the antenna, the denser the distribution of reflective points and the smaller the proportion of the light-transmitting area.

6. A patterned reflective film according to claim 5, characterized in that, In the area where the reflective points are densely distributed in the gradient pixel array, a light-transmitting grid line with a random grid pattern is also provided as a supplementary wave-transmitting channel.

7. A patterned reflective film according to claim 1, characterized in that, The reflective layer (2) is a copper layer, and a blackening layer (2B) is also provided on its surface. The thickness of the blackening layer (2B) is 20-150nm, and the color of the blackening layer (2B) is controlled to be blue, red or black by adjusting the ratio of oxygen and nitrogen in the preparation process.

8. A patterned reflective film according to claim 7, characterized in that, The blackening layer (2B) is prepared by any of the following methods: ① Preparation of the blue blackening layer: Control the total pressure to 0.5-2 Pa, Ar flow rate to 30-50 sccm, N2 flow rate to 50-80 sccm, O2 flow rate to 5-15 sccm, and RF or DC power density to 0.5-1.5 W / cm². 2 Plasma treatment for 30-90 seconds; ② Preparation of the red blackening layer: Control the total pressure to 0.5-2 Pa, Ar flow rate to 30-50 sccm, N2 flow rate to 30-45 sccm, O2 flow rate to 20-35 sccm, and RF or DC power density to 1.0-2.0 W / cm². 2 Plasma treatment for 60-180 seconds; ③ Preparation of the blackened layer: Control the total pressure to 0.5-2 Pa, Ar flow rate to 30-50 sccm, N2 flow rate to 10-30 sccm, O2 flow rate to 40-60 sccm, and RF or DC power density to 1.5-3.0 W / cm². 2 Plasma treatment for 150-180 seconds.

9. A patterned reflective film according to claim 1, characterized in that, The reflective layer (2) is a quarter-wavelength optical film stack composed of alternating deposition of a high-refractive-index material layer (201) and a low-refractive-index material layer (202), and its optical thickness satisfies n·d=λ0 / 4, where n is the refractive index of the thin film material, d is its physical thickness, and λ0 is the target center wavelength.

10. A patterned reflective film according to claim 9, characterized in that, The high refractive index material layer (201) is TiO2 or Nb2O5, and its n is 2.2-2.4; the low refractive index material layer (202) is SiO2 or MgF2, and its optical refractive index n is 1.38-1.

46.

11. A patterned reflective film according to claim 1, characterized in that, The light reflectivity of the reflective layer (2) with a thickness of 825 nm exceeds 95%, and the light reflectivity of the reflective layer (2) with a thickness of 2 μm exceeds 99%.

12. The fabrication process of a patterned reflective film as described in any one of claims 1-11, characterized in that, Includes the following steps: S1. Magnetron sputtering: A basic reflective layer is prepared on the surface of a substrate using magnetron sputtering. S2. Coating: A photocurable resin layer (4) is coated on the base reflective layer. S3. Photocuring: The photocurable resin layer (4) is selectively exposed by a photomask (3) with a preset pattern. The photomask (3) is divided into a shielding area (301) and a cutout area (302). The shielding area (301) covers the surface of the photocurable resin layer (4), so that the resin in the exposed area crosslinks and cures to form a cured area (401), and the unexposed area forms an uncured area (402). The cured area (401) covers the reflective unit (2C) of the reflective layer material, and the unexposed area forms an uncured area (402). Below the uncured area (402) is the light-transmitting area (2D) of the reflective layer material. S4. Etching: Sequentially remove the uncured area (402) and the light-transmitting area (2D) below it, so that the reflective layer material forms a patterned structure corresponding to the preset pattern; S5. Remove the cured film: Remove the cured area (401) to obtain the patterned reflective layer (2), that is, to obtain the finished patterned reflective film.

13. The fabrication process of a patterned reflective film according to claim 12, characterized in that, The S1 uses polyethylene terephthalate (PET) or polyimide (PI) film as the substrate layer (1), and plasma or ultraviolet ozone cleaning is required before use.

14. The fabrication process of a patterned reflective film according to claim 12, characterized in that, The preparation process of the basic reflective layer of the metallic material is as follows: Step A1. Ignition and Pre-sputtering: The substrate is transferred to the bottom of the process chamber where the target has been installed. Ar gas is introduced, with the flow rate precisely controlled at 20-80 sccm. The working pressure in the chamber is stabilized at 0.3-1.0 Pa. A DC power supply is applied to the Al or Cu target, and the power density is gradually increased to 2-6 W / cm³. 2 ; Step A2. Formal Deposition: Remove the baffle, maintain stable Ar gas flow rate, pressure and power, and set the deposition rate to 0.5-3 nm / s. When the set value is reached by the film thickness monitor, automatically turn off the target power supply and move the baffle back, thus ending the deposition process.

15. The fabrication process of a patterned reflective film according to claim 12, characterized in that, The preparation process of the basic reflective layer of the metal oxide material is as follows: Step B1. Establish a stable process point: First, introduce Ar at a flow rate of 40 sccm, adjust the pressure to 0.3-0.5 Pa, and turn on the power supply to the Ti, Si, or Nb target at a power density of 3-5 W / cm³. 2 Gradually increase the O2 flow rate until the deposition rate stabilizes; Step B2. Formal Deposition: After the process stabilizes, remove the baffle and control the Ar flow rate at 40 sccm, the O2 flow rate at 8 sccm, the working pressure at 0.4 Pa, and the power density at 4 W / cm³. 2 The substrate bias is: RF, 13.56MHz, power density 100W / m². 2 The deposition rate is 0.1-1.0 nm / s, and the endpoint is controlled by a film thickness monitor to obtain a single layer of high refractive index material (201) or low refractive index material (202). Step B3. Alternating deposition: The substrate will be transferred to the next process chamber containing different targets. Step B2 is repeated to deposit low refractive index material layer (202) or high refractive index material layer (201) in sequence. After all films are deposited, the substrate is transferred back to the sample chamber, high-purity nitrogen is introduced into the sample chamber to atmospheric pressure, and the sample is taken out to obtain a base reflective layer with alternating deposition of high refractive index material layer (201) and low refractive index material layer (202).

16. The fabrication process of a patterned reflective film according to claim 12, characterized in that, The S2 method uses slot coating or spin coating to uniformly coat the photocurable resin solution onto the surface of the reflective layer, and then bakes it in an oven at 70-90℃ for 1-2 minutes to form a resin layer with a dry film thickness of about 3-8μm.

17. The fabrication process of a patterned reflective film according to claim 16, characterized in that, The photocurable resin solution comprises the following components by weight percentage: 40%-55% bisphenol A type epoxy acrylate prepolymer or aliphatic polyurethane acrylate, 35%-50% reactive diluent, 4%-8% photoinitiator, 0.3%-1.5% γ-(methacryloyloxy)propyltrimethoxysilane, 0.1%-0.5% polyether-modified polydimethylsiloxane, 0.1%-0.3% non-silicone polymer defoamer, and 0.2%-0.5% p-methoxyphenol or 2,6-di-tert-butyl-p-cresol.

18. The fabrication process of a patterned reflective film according to claim 12, characterized in that, The S3 method uses an exposure machine equipped with a high-pressure mercury lamp or a 365nm LED surface light source to bring the photomask (3) with the designed target pattern into close contact with the sample coated with the resin layer, with an exposure energy of 200-600mJ / cm². 2 The exposure time is calculated using the following formula: 。 19. The fabrication process of a patterned reflective film according to claim 12, characterized in that, S4 involves processing different reflective layer materials separately: Path 1. The reflective layer material is a metallic material: For the aluminum reflective layer: Take 10g of sodium hydroxide and 5g of sodium gluconate, dissolve them in 800mL of deionized water, stir to dissolve, add 150mL of N-methylpyrrolidone, and finally add 1mL of Triton X-100. Stir well and bring the volume to 1L. Control the working temperature at 45±5℃ to obtain the aluminum treatment solution. Immerse the exposed sample in the aluminum treatment solution and etch for 1-5 minutes, then clean and dry. For the copper reflective layer: Take 150g of copper chloride, dissolve it in about 600mL of deionized water, slowly add 100mL of concentrated hydrochloric acid, then add 50mL of phosphoric acid, stir and cool, then add 80mL of dimethyl sulfoxide, and bring the volume to 1L. Control the working temperature at 40±5℃ to obtain the copper treatment solution; immerse the exposed sample in the copper treatment solution, etch for 1-5 minutes, and then clean and dry. Path 2. The reflective layer material is a metal oxide material: Step S4a. Oxygen plasma removes non-curable resin: The sample is placed in a reactive ion etching or plasma ashing device, oxygen is introduced, the flow rate is set to 80 sccm, the chamber pressure is 1.0 Pa, the radio frequency power is 300 W, and the processing time is 90-180 seconds. Step S4b: Reactive ion etching of the oxide reflective layer: The etching gas is continuously replaced in the same device to sequentially remove the light-transmitting areas (2D) of the high-refractive-index material layer (201) and the low-refractive-index material layer (202): For the SiO2 layer: use a mixed gas of CF4 at a flow rate of 40 sccm and O2 at a flow rate of 10 sccm, pressure of 0.5 Pa, power of 400 W, and etch to the endpoint; For TiO2 or Nb2O5 layers: use a mixed gas of Cl2 at a flow rate of 30 sccm and BCl3 at a flow rate of 20 sccm, pressure of 0.8 Pa, power of 350 W, and etch to the endpoint; After etching, the surface is cleaned briefly with Ar gas.

20. The fabrication process of a patterned reflective film according to claim 12, characterized in that, S5 includes the following process: After S4, the patterned reflective structure has been formed, but the surface is still covered with a cured resin layer. The sample is immersed in N-methylpyrrolidone heated to 60°C and then subjected to ultrasonic treatment at 50W for 3-8 minutes until the cured resin is completely swollen and detached. After cleaning and drying, a patterned reflective film product with a clean surface and clear pattern is obtained.

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