Method for processing and preparing cover plate glass with superhard optical coating film

Abstract

The invention is applicable to the field of cover plate glass processing, and provides a method for processing and preparing a cover plate glass with a superhard optical coating, which comprises the steps of glass substrate pretreatment, multi-layer superhard coating layer preparation, AF anti-fingerprint film preparation and post-treatment detection. According to the invention, the glass substrate is subjected to basic pretreatment (cleaning and plasma treatment), the Mohs hardness of the superhard coating layer can reach 5 when an evaporation process is adopted, and the Mohs hardness can reach 6 when a sputtering process is adopted; the initial water drop angle is larger than or equal to 115 degrees, the water drop angle is still larger than or equal to 102 degrees after 2500 times of friction tests, and the rubber friction tests can reach more than 6300 times; the total thickness of the film layer is controlled to be 30-100 nm, the film layer is adaptive to cover plate glass with different sizes of more than 1-20 inches (small-size adaptive evaporation / sputtering and large-size adaptive magnetron sputtering), the process is compatible with a continuous film coating line, and the film layer is suitable for processing of intelligent watch glass, intelligent mobile phones and small-size touch screen cover plate glass and has good practicability and mass production potential.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of cover plate glass processing, and particularly relates to a cover plate glass processing preparation method with superhard optical coating. BACKGROUND

[0002] With the rapid development of smart wearable devices (such as smart watches), smart phones and other consumer electronics, the cover plate glass as the core protection component of the terminal device, its "surface scratch resistance" and "anti-fouling" performance have become the core demand of users. In the current market, the cover plate glass (such as ordinary aluminum-silicon glass) without superhard coating treatment has a maximum Mohs hardness of only 5, which is easily scratched by hard objects such as keys (Mohs hardness 5.5) and sand (Mohs hardness 7) in daily use, especially the watch mirror of the smart watch due to the special wearing scene, the scratch problem has become the core pain point of the product; at the same time, the traditional cover plate glass has no anti-fouling treatment, and the surface is easy to leave fingerprints and oil stains, which is difficult to clean and seriously affects the user experience.

[0003] The existing superhard coating technology of cover plate glass mainly has the following two core problems:

[0004] Insufficient surface hardness and weak scratch resistance: some technologies only use single SiO2 coating (Mohs hardness 5) or simplified double-layer coating structure (SiO2+AF), which cannot effectively resist daily hard object scratching. After 1000 times of simulated friction test (800 mesh sandpaper, 100g load), the transmittance decreases by 8~10%, the surface scratch is obvious, and the product service life is shortened;

[0005] Lack of anti-fouling performance and poor adhesion of film layer: most technologies do not set the anti-fingerprint (AF) layer, or the AF layer and the bottom coating are not closely combined, resulting in rapid decay of anti-fouling effect - although the initial water drop angle can reach more than 100°, but after 1000 times of friction, the water drop angle drops to below 80°, which cannot maintain the anti-fouling ability for a long time; at the same time, part of the coating process (such as simple evaporation coating) does not effectively pretreat the glass substrate, and the adhesion between the film layer and the substrate is weak, and the film layer shedding rate can reach 10~15% in high-low temperature cycle test (-20℃~60℃, 50 cycles);

[0006] In addition, the existing technology has the problem of "poor process adaptability": part of the superhard coating technology is only suitable for small size glass (such as less than 10 inches), which cannot meet the mass production demand of large screen touch screen (more than 20 inches);

[0007] And most of the technologies do not form a standardized multi-layer coating structure, and the film layer has poor performance stability, and the hardness and anti-fouling effect difference of different batches of products can reach 15~20%, which is difficult to adapt to high-capacity continuous coating line;

[0008] Therefore, a cover plate glass processing preparation method with superhard optical coating is needed to solve the above problems. SUMMARY

[0009] The purpose of the embodiment of the present application is to provide a cover glass processing and preparation method with super-hard optical coating, so as to solve the problems in the background art.

[0010] To achieve the above purpose, the present application provides the following technical scheme:

[0011] A cover glass processing and preparation method with super-hard optical coating, comprising the following steps:

[0012] S1, glass substrate pretreatment, cleaning treatment is performed on the glass substrate to remove surface foreign matter, and then plasma treatment is performed to improve surface adhesion;

[0013] S2, multi-layer super-hard coating layer preparation, using evaporation or sputtering process to deposit multi-layer alternating super-hard coating layer on the surface of the pretreated glass substrate, the multi-layer alternating super-hard coating layer is formed by stacking SiO2 layer and super-hard material layer alternately, the super-hard material is selected from at least one of DLC, Si3N4, Al2O3, SiAlN and SiC;

[0014] S3, AF anti-fingerprint film preparation, using evaporation coating process to coat AF anti-fingerprint film on the surface of the multi-layer super-hard coating layer;

[0015] S4, post-treatment detection, detecting the hardness, water drop angle and friction frequency of the coated cover glass, and cutting and edging according to the requirements after passing the detection to obtain the finished product.

[0016] Further technical scheme, the cleaning treatment in step S1 is conventional water washing or solvent cleaning, to ensure that the surface of the glass substrate is free of oil stains and dust; the plasma treatment uses Ar gas as the gas source, generates glow plasma by ion source to bombard the glass surface, so that the surface energy of the glass can reach 28~30 dynes.

[0017] Step S1 is the basis for improving the adhesion of the coating layer, which includes two core links:

[0018] Cleaning treatment: through conventional water washing or solvent cleaning, remove oil stains, dust, fingerprints and other foreign matter on the surface of the glass substrate, avoid foreign matter to cause pinholes and bubbles in the coating layer, and ensure the cleanliness of the substrate surface (surface contaminant residual amount ≤0.5mg / m²), to provide "impurity-free" substrate for subsequent coating;

[0019] Plasma treatment: Ar gas is used as the plasma source, and a glow plasma (PLASMA) is generated by the ion source of the PVD coating machine. The high-energy plasma bombards the glass surface, breaks the Si-O-Si covalent bond on the glass surface, generates active sites, and increases the surface energy of the glass surface to 28-30 dynes. The increase in surface energy can significantly enhance the adhesion between the subsequent coating and the substrate, prevent the film from falling off, and compared with traditional chemical etching treatment, the plasma treatment has no chemical reagent residue and no damage to the glass substrate.

[0020] Further technical solutions, the specific structure of the multilayer alternating superhard coating layer in step S2 is selected from one of the following 11 ways:

[0021] Sputtering process: SiO2 / DLC / Si3N4 / SiO2 / AF (AF is the product of step S3, the same below);

[0022] Sputtering process: SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / AF;

[0023] Sputtering process: SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / DLC / SiO2 / AF;

[0024] Sputtering process: SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / AF;

[0025] Sputtering process: SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / DLC / SiO2 / AF;

[0026] Sputtering process: SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / AF;

[0027] Sputtering process: SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / DLC / SiO2 / AF;

[0028] Sputtering process: SiO2 / Si3N4 / Al2O3 / SiO2 / AF;

[0029] Sputtering process: SiO2 / Si3N4 / Al2O3 / SiO2 / DLC / SiO2 / AF;

[0030] Evaporation process: SiC+SiO2 / AF;

[0031] Evaporation process: SiO2+SiC+SiO2 / AF.

[0032] Further technical solutions, the total thickness of the multilayer alternating superhard coating layer in step S2 is 30-75 nm, wherein the thickness of the single layer SiO2 is controlled to be 5-10 nm, and the thickness of the single layer superhard material layer is controlled to be 5-6 nm. The film thickness is monitored and controlled in real time by a crystal oscillator.

[0033] Further technical solutions, the evaporation process in step S2 adopts a vacuum vapor deposition coating machine (PVD), a molecular pump is used to make the vacuum degree of the coating cavity reach 3.0×10⁻ 5 ~8.0×10⁻ 5 torr, Ar gas is introduced to prevent oxidation of the film material, and SiO2 or superhard material is gasified and deposited on the glass surface by strong current heating of the crucible; the sputtering process adopts target material magnetron sputtering, and a molecular pump is used to maintain the cavity vacuum to ensure the adhesion of the film layer.

[0034] Step S2 is the core of realizing the "basic scratch resistance" performance, and the technical logic is as follows:

[0035] Multi-layer alternating structure design: adopt "SiO2 layer + superhard material layer" alternating stacking structure, wherein the SiO2 layer has the advantages of "high light transmittance (visible light transmittance ≥95%) + easy combination with AF layer", which can be used as the connection transition of the film layer and the AF layer; the superhard material layer (DLC, Si3N4, Al2O3, etc.) has higher hardness (Si3N4 Mohs hardness 6-7, DLC Mohs hardness 7-8), which can significantly improve the overall scratch resistance of the film layer. By alternating stacking (such as SiO2 / Si3N4 / SiO2 / Si3N4), a balance between "hardness" and "light transmittance" can be achieved, while avoiding the problem of stress concentration of single material film layer;

[0036] Dual-process adaptive design: for different size requirements, two process options of evaporation and sputtering are provided - the evaporation process has low equipment cost and simple operation, and is suitable for small size cover glass below 10 inches (such as smart watch mirror); the sputtering process (target material magnetron sputtering) has higher film density and stronger adhesion, and is suitable for large screen cover glass above 20 inches (such as flat panel display). Both processes maintain high vacuum (3.0×10⁻ 5 ~8.0×10⁻ 5 torr) in the cavity by a molecular pump, Ar gas is introduced to prevent oxidation of the film material, and the purity of the film layer is ensured;

[0037] Accurate control of film thickness: real-time monitoring of film thickness by crystal oscillator instrument, single layer SiO2 controlled at 5~10nm (too thick easy to cause film cracking, too thin unable to play a transition role), single layer super hard material layer controlled at 5~6nm (too thick easy to cause film internal stress to increase, too thin unable to improve hardness), total thickness 30~75nm, to ensure stable film performance and not affect the glass light transmission effect.

[0038] Further technical solutions, the preparation of the AF anti-fingerprint film in step S3 is specifically: placing the AF film material on the molybdenum boat connected with the electrode, heating the molybdenum boat by electric current to evaporate the AF film material, and uniformly attaching the AF film material to the surface of the multi-layer super hard coating layer under the action of plasma, with the thickness of the AF anti-fingerprint film controlled at about 25nm.

[0039] Step S3 is the key to realize the "anti-dirt" performance, and the technical logic is as follows:

[0040] AF film material selection and deposition: the AF anti-fingerprint film material is a fluorine-containing polymer, which is evaporated by heating the molybdenum boat - placing the AF film material in the molybdenum boat connected with the electrode, and the temperature of the molybdenum boat rises to 200~300℃ after electrification, so that the AF film material is evaporated into a particle state and uniformly attached to the surface of the multi-layer super hard coating layer under the action of plasma;

[0041] Functional synergy: the AF film layer not only can reduce the friction coefficient of the glass surface (from 0.3 to below 0.1), but also can form a chemical bond with the SiO2 layer (the fluorine group in the AF reacts with the hydroxyl group in the SiO2), thereby enhancing the adhesion of the AF layer and "solidifying" the multi-layer super hard coating layer to avoid the edge of the film layer from falling off, realizing the dual effects of "anti-dirt" and "film solidification".

[0042] Further technical solutions, the specific standards for detection in step S4 are:

[0043] Hardness detection uses a Mohs hardness pen, and the Mohs hardness is ≥5 when using evaporation process and ≥6 when using sputtering process;

[0044] Water droplet angle detection uses a contact angle measuring instrument, and the initial water droplet angle is ≥115°, and the water droplet angle is ≥102° after 2500 times of friction test (load 100g);

[0045] Friction frequency detection uses a rubber eraser friction test, and the friction frequency is ≥6300 times (rubber eraser model: 7000N, friction speed 100mm / min).

[0046] Step S4 is the core to ensure the consistency of product quality, and the roles of each detection item are as follows:

[0047] Hardness detection (Mohs hardness 5~6): to ensure that the cover plate glass can resist daily mild scratches (such as keys, desktop friction), and avoid surface scratches;

[0048] Water drop angle detection (initially >=115°, after rubbing >=102°): measure the anti-fouling performance - high water drop angle means that liquid (such as sweat, water stains) on the glass surface is spherical and does not easily remain, and the water drop angle is stable after rubbing, which ensures that the anti-fouling effect is long-term effective;

[0049] Rubbing frequency detection (>=6300 times): verify the durability of the film layer - simulate daily rubbing with a rubber eraser to ensure that the film layer does not fall off and the anti-fouling effect does not decrease in long-term use;

[0050] Size adaptation processing: according to the requirements of terminal products (such as smart watch mirror size 40mm*40mm, smart phone cover plate 150mm*75mm), laser cutting (precision ±0.1mm) or diamond tool cutting is adopted, and edge grinding treatment (remove sharp edges, grinding radius 2~5mm) is adopted to meet diversified application scenarios.

[0051] Further technical solutions, the glass substrate is selected from ordinary aluminum-silicon glass, microcrystalline glass or ceramic sheet; the size range is 1 inch to 20 inches or more, and the touch screen cover plate glass with a screen size of less than 10 inches can be evaporated or sputtered, and the touch screen cover plate glass with a screen size of more than 20 inches is preferably sputtered by a vacuum magnetron sputtering process.

[0052] Compared with the prior art, the beneficial effects of the present application are:

[0053] The present application significantly improves the scratch resistance of the cover plate glass and solves the core problem: through "SiO2+ super-hard material multilayer alternating plating film", the Mohs hardness of the cover plate glass surface reaches 5~6 (evaporation process 5, sputtering process 6), compared with uncoated glass (Mohs 5), the hardness of the sputtering process product is increased by more than 20%; according to industry standard test: after 2500 times of rubbing test (100g load, rubber eraser rubbing) of the cover plate glass using sputtering process, the surface has no obvious scratch, and the transmittance decreases only by 1~2%; while the traditional single SiO2 coated glass has obvious scratches after the same test, and the transmittance decreases by 6~8%; in actual use scenarios, it can effectively resist key (Mohs 5.5), coin (Mohs 3~4) and other daily hard objects scratching, especially suitable for smart watch mirror, solving the core problem of "easy to scratch when wearing";

[0054] The present application has long-term anti-fouling performance, improves user experience: through plating AF anti-fingerprint film, the initial water drop angle of the cover plate glass reaches more than 115 degrees, sweat and water stains are spherical on the surface, and fingerprints and oil stains are not easy to remain; after 2500 times of friction test, the water drop angle still remains more than 102 degrees, and the anti-fouling effect attenuation rate is only 11.3%, which is much better than that of traditional products without AF layer or single AF layer (attenuation rate 40-50%); in daily use, users only need to wipe the glass surface, which greatly reduces the cleaning difficulty;

[0055] The present application has strong process adaptability and covers multiple size and scene requirements: a "evaporation + sputtering" dual-process selection is provided, which is suitable for different sizes of cover plate glass of 1 inch to 20 inches or more: small screens below 10 inches can use evaporation process, which has low equipment investment and high production efficiency (tact time ≤40s / piece); large screens above 20 inches can use magnetron sputtering process, which has stronger film adhesion and more stable performance; at the same time, the process can adapt to high-capacity continuous coating lines, without the need to add special equipment, and only the coating target or evaporation crucible needs to be adjusted to realize mass production, which adapts to the diversified product requirements in the consumer electronics field;

[0056] The present application has strong film adhesion and high product reliability: through the double protection of "plasma pretreatment + SiO2 transition layer", the adhesion of the multi-layer superhard coating layer to the glass substrate reaches 4B level, and the adhesion of the AF layer to the bottom coating layer reaches 5B level; in high and low temperature cycle test, the film layer shedding rate is 0, without blistering and cracking phenomenon; in the damp heat test (60℃ / 90%RH, 500h), the transmittance only decreases by 0.5-1%, and the anti-fouling effect does not decrease obviously, which meets the reliability requirements of consumer electronic products for "2-3 years of service life";

[0057] The present application has high process stability and high product yield: through the standardized "multi-layer structure design + crystal vibration control film thickness + dual-process parameters", the quality fluctuation caused by human operation error can be effectively avoided; through mass production verification, the product yield can reach more than 92%, which is 12-17% higher than that of the traditional simplified coating process (yield 75-80%); at the same time, the hardness difference of different batches of products is ≤0.5 level, and the water drop angle difference is ≤3 degrees, which ensures the product quality consistency, reduces the production cost and waste rate.

[0058] In order to more clearly illustrate the structural characteristics and effects of the present application, the present application will be described in detail below with reference to the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 It is a multi-layer film layer structure stacking diagram of the present application;

[0060] Figure 2 It is a PVD superhard coating machine structure schematic diagram of the present application;

[0061] Figure 3 The whole process flow chart of the present application. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0063] The specific implementation of the present application is described in detail below in combination with specific examples.

[0064] Example 1: smart watch mirror (small size, evaporation process);

[0065] This example is directed to a smart watch mirror (size 40mm x 40mm, thickness 0.5mm, substrate is microcrystalline glass), which adopts an evaporation process to prepare a "SiO2+SiC+SiO2 / AF" structure, and the specific steps are as follows:

[0066] Step 1: glass substrate pretreatment;

[0067] Cleaning treatment: rinse the surface of the glass substrate with deionized water, then wipe it with isopropanol (purity ≥ 99.7%), and remove the surface oil and fingerprints;

[0068] Plasma treatment: place the cleaned substrate into the vacuum chamber of the PVD coating machine, close the chamber, and then pump it to 5.0 x 10⁻ 5 torr through the pump port; introduce Ar gas (flow rate 15 sccm), turn on the ion source (power 90 W), generate glow plasma to bombard the surface of the substrate, and the treatment time is 5 min, so that the surface of the substrate can reach 29 dynes.

[0069] Step 2: preparation of multi-layer superhard coating layer (evaporation process);

[0070] First layer SiO2 evaporation: turn on the first crucible heating current (120 A) to make the SiO2 film material (purity 99.9%) in the crucible gasify, monitor the film thickness by the crystal oscillator instrument, and turn off the current after depositing 5 nm;

[0071] SiC evaporation: replace the second crucible (place SiC film material, purity 99.9%), turn on the heating current (140 A), deposit a 6 nm SiC layer, and monitor the film thickness by the crystal oscillator instrument;

[0072] Second layer SiO2 evaporation: use the first crucible again to deposit a 5 nm SiO2 layer;

[0073] Total thickness of multi-layer: 5nm (SiO2) + 6nm (SiC) + 5nm (SiO2) = 16nm.

[0074] Step 3: AF fingerprint-proof film preparation

[0075] Put the AF film material (model: AF-100, fluoropolymer) into a molybdenum boat, turn on the molybdenum boat heating current (60 A), and raise the temperature to 250°C to evaporate the AF film material; at the same time, keep the ion source on (power 80 W) to assist in the uniform deposition of AF particles; monitor through a crystal oscillator instrument, turn off the current after depositing 25 nm, and complete the preparation of the AF layer.

[0076] Step 4: Post-processing detection and processing

[0077] Hardness detection: use a Mohs hardness pen (model MH-5) to test, use a pen with hardness 5 to scratch without scratches, and use a pen with hardness 6 to scratch with slight scratches, and determine the Mohs hardness to be 5;

[0078] Water drop angle detection: use a contact angle measuring instrument (model: JC2000D) to test, the initial water drop angle is 118°, and after 2500 times of friction test (eraser: 7000N, load 100g, speed 100mm / min), the water drop angle is 105°;

[0079] Friction frequency detection: eraser friction test, after 6500 times of friction, the film layer has no peeling and no obvious scratches on the surface;

[0080] Cutting and edging: use a laser cutting machine (wavelength 1064nm) to cut the substrate into 40mm x 40mm, and then use a diamond grinding wheel to edge (edge radius 2mm) to obtain a finished smart watch mirror.

[0081] In this embodiment, the effects of the embodiment are detailed as follows:

[0082] Good scratch resistance: smart watch mirrors are easily in contact with wrist sweat and desk friction in daily wear. The Mohs hardness of the product of the embodiment is 5, and the surface has no scratches after 100 times of key scraping (load 50g), which is much better than uncoated microcrystalline glass (obvious scratches after scraping);

[0083] Excellent stain resistance: the initial water drop angle is 118°, and the sweat drops on the surface can roll off directly without residue; after wearing for 1 month, the amount of fingerprint residue on the surface is reduced by 80% compared to traditional watch mirrors, and only dry cloth wiping is needed for cleaning;

[0084] Process adaptation to small size: the evaporation process equipment has low cost (single equipment investment ≤500,000 yuan), and the tact time is 35s / piece, which is suitable for the production needs of "small size and multiple batches" of smart watch mirrors, with a yield of 93% and an increase in production cost of only 3-5%.

[0085] Example 2: smart phone cover plate (medium size, sputtering process)

[0086] The embodiment differs from embodiment 1 in that the embodiment is directed to a smart phone cover plate (size 150 mm x 75 mm, thickness 0.7 mm, base material ordinary aluminum-silicon glass), and a "SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / AF" structure is prepared by a sputtering process, and the specific steps are as follows:

[0087] Step 1: glass substrate pretreatment;

[0088] Cleaning treatment: ultrasonic cleaning with deionized water (frequency 28 kHz, time 10 min), followed by 2 min of deionized water spray washing, 80°C hot air drying for 5 min to remove surface dust and oil;

[0089] Plasma treatment: place the dried substrate into the cavity of the magnetron sputtering film coating machine, vacuum to 3.0 x 10⁻ 5 torr; introduce Ar gas (flow rate 18 sccm), start the ion source (power 100 W), and plasma bombard the substrate surface for 8 min, and the surface energy reaches 30 dynes.

[0090] Step 2: preparation of multilayer superhard film layer (sputtering process);

[0091] First layer SiO2 sputtering: use SiO2 target material (purity 99.95%, density ≥ 95%), sputtering power 150 W, target-to-substrate distance 10 cm, substrate rotation speed 8 r / min, sputtering time 5 min, film thickness 8 nm (crystal oscillator monitor);

[0092] First layer Si3N4 sputtering: replace Si3N4 target material (purity 99.9%, density ≥ 94%), sputtering power 160 W, target-to-substrate distance 10 cm, substrate rotation speed 8 r / min, sputtering time 6 min, film thickness 6 nm;

[0093] Second layer SiO2 sputtering: use SiO2 target material again, parameters same as first layer, film thickness 8 nm;

[0094] Second layer Si3N4 sputtering: use Si3N4 target material again, parameters same as first layer, film thickness 6 nm;

[0095] Third layer SiO2 sputtering: use SiO2 target material, parameters same as first layer, film thickness 8 nm;

[0096] Total thickness of multilayer: 8+6+8+6+8=36 nm.

[0097] Step 3: AF anti-fingerprint film preparation;

[0098] Put the AF film material into the molybdenum boat, start the molybdenum boat heating module of the magnetron sputtering film coating machine, the current is 70 A, the temperature rises to 280 DEG C, the AF film material evaporates; at the same time, the cavity Ar atmosphere (flow rate 15 sccm) is kept, the substrate rotation speed is 5 r / min, and the uniform deposition of the AF layer is ensured; after depositing 25 nm, the heating is turned off, and the preparation of the AF layer is completed.

[0099] Step 4: Post-processing detection and processing;

[0100] Hardness detection: Mohs hardness pen test, no scratch on the pen scratch of hardness 6, slight scratch on the pen scratch of hardness 7, and the Mohs hardness is judged to be 6;

[0101] Water drop angle detection: initial water drop angle 120 DEG, water drop angle 108 DEG after 2500 times of friction test, and the anti-fouling effect attenuation rate is only 10%;

[0102] Friction frequency detection: eraser friction test, no film layer falls off after 7000 times of friction, and the light transmittance (550 nm) still remains 92% (initial 93%);

[0103] Cutting and edging: cutting into 150 mm x 75 mm by using a laser cutting machine (wavelength 532 nm), and diamond grinding wheel edging (edging radius 2.5 mm), to obtain a smart phone cover plate finished product.

[0104] In this embodiment, the effects of the embodiment are embodied in detail as follows:

[0105] Excellent scratch resistance: the smart phone cover plate is easy to contact keys and sand in the pocket, the Mohs hardness of the product of the embodiment is 6, after 100 times of sand (800 mesh) friction test (load 100 g), the surface has no obvious scratch, and the light transmittance only decreases by 0.8%, which is much better than the traditional single SiO2 coated cover plate (obvious scratch, light transmittance decreases by 5%);

[0106] Strong anti-fouling durability: the initial water drop angle is 120 DEG, the fingerprints and oil stains are easy to clean on the surface, after 30 days of daily use (500 times of touch per day), the water drop angle still remains 105 DEG, the anti-fouling effect does not obviously attenuate, and users do not need to frequently wipe;

[0107] Adapt to mass production demand: the sputtering process film layer has strong adhesion (crosshatch method 4B level), no film layer falls off after high-low temperature cycle test (-20 DEG C ~ 60 DEG C, 50 times); the beat time is 60 s / piece, which can adapt to the smart phone cover plate mass production production line (demand beat ≤90 s / piece), the yield reaches 94%, the production cost increases by 6%, and it has market competitiveness.

[0108] Working principle and use process of the application:

[0109] Around the core process of "pretreatment-multilayer superhard coating-AF antifouling", through the synergistic effect of each process, the performance goal of "basic scratch resistance + long-term antifouling" of cover glass is realized. The specific process and technical logic are described as follows:

[0110] There are four core stages: substrate pretreatment stage → multilayer superhard coating stage → AF antifouling coating stage → detection and post-processing stage. Each stage is closely linked to form a complete system of "substrate activation → hardness improvement → antifouling empowerment". The specific process sequence is: substrate selection → pretreatment → multilayer superhard coating → AF coating → detection → cutting and edging → finished product.

[0111] Substrate pretreatment stage: Build an "activated and clean" substrate surface.

[0112] Cleaning principle: Through deionized water flushing or isopropyl alcohol wiping, use the wetting effect of liquid to dissolve surface oil stains, and physically strip dust, fingerprints and other foreign matter. For stubborn oil stains, ultrasonic cleaning (frequency 28 kHz) can be used to enhance the stripping effect of pollutants through cavitation effect, ensuring that the substrate surface is free of impurities. If there are pollutants on the substrate surface, it will cause pinholes, bubbles in the subsequent coating, and reduce the adhesion of the film layer.

[0113] Plasma activation principle: Ar gas is ionized to form plasma (containing Ar⁺ ions and electrons) under the action of high-frequency electric field (ion source power 80~100W). High-energy Ar⁺ ions bombard the substrate surface, on the one hand, breaking the Si-O-Si bond on the surface to generate a large number of hydroxyl groups (-OH) and unsaturated bonds (active sites). These active sites can form Si-O bonds with Si atoms in SiO2 film material, enhancing the adhesion between film and substrate. On the other hand, ion bombardment forms micro-pits on the substrate surface (roughness Ra decreases from 0.3 nm to less than 0.1 nm), increasing the contact area between the substrate and the film layer, and improving the adhesion from both "chemical bonding" and "physical anchoring". Finally, the surface energy reaches 28~30 dynes (when the surface energy is greater than or equal to 25 dynes, the film material can spread well).

[0114] Multilayer superhard coating stage: Build "alternating and superimposed" scratch-resistant film layer.

[0115] Evaporation process principle (small size): The molecular pump evacuates the cavity to 3.0×10⁻ 5 ~8.0×10⁻ 5Torr high vacuum, reduce impurity gas (O2, H2O) and film material particles collision; strong current (100~150A) heating crucible, so that SiO2 / SiC and other film materials absorb energy from solid to gas (gasification temperature: SiO2 about 1700℃, SiC about 2200℃), forming a "film particle flow"; particle flow in a vacuum environment to the substrate, gradually deposited to form a film layer; umbrella with the rotation of the substrate (5~8r / min), to ensure the uniformity of the film layer; crystal oscillator through the principle of "film deposition resulting in crystal oscillator frequency change", real-time calculation and control of film thickness (accuracy ±0.1nm), to avoid the film layer is too thick or too thin;

[0116] Sputtering process principle (large size): magnetic sputtering by "magnetic field to constrain the electron" to enhance the collision probability of electrons and Ar gas, improve the yield of Ar⁺ ion; Ar⁺ ion under the action of electric field to accelerate the target (such as SiO2 target, Si3N4 target), target atoms get energy from the target surface (sputtering yield: SiO2 about 0.5 atoms / ion, Si3N4 about 0.4 atoms / ion), forming a "target atom flow"; atom flow deposition to form a film layer on the substrate surface, the optimization of target base spacing (10cm) and rotation speed (8r / min) can ensure that the atom flow energy is moderate, forming a dense film layer (density≥90%);

[0117] Multi-layer alternating principle: SiO2 layer of low refractive index (1.46) can reduce the film reflection, to ensure the light transmittance (≥92%); Si3N4 / DLC and other superhard layer of high hardness can improve the scratch resistance, the alternation of the two can avoid the "stress concentration" problem of single material film layer - such as single Si3N4 film layer internal stress about-300MPa, easy to crack; and SiO2 / Si3N4 alternating layer internal stress can be reduced to-150MPa or less, the stability of the film layer is significantly improved;

[0118] AF anti-fouling coating stage: build a "low surface energy" anti-fouling layer;

[0119] AF film evaporation principle: molybdenum boat under the action of current (50~80A) heating, the temperature rises to 250~300℃, AF film (containing fluorine polymer) is evaporated into small molecules particles; plasma (ion source power 80W) can make AF particles get additional energy, more easily react with the hydroxyl group of the bottom SiO2 (-OH+-CF2-→-O-CF2-+H2), forming a stable chemical bond; at the same time, the rotation of the substrate ensures the uniform coverage of AF particles, avoiding the local anti-fouling effect is not enough;

[0120] Antifouling principle: AF film layer surface contains a large number of fluorine groups (-CF3, -CF2-), and its surface energy is extremely low (about 15 mN / m), which is much lower than the surface energy of water (72 mN / m) and oil stains (30~40 mN / m), so that the liquid cannot spread on the film layer surface and can only roll in a spherical shape, thereby realizing the "fingerprint and oil stain prevention" effect; at the same time, the low friction coefficient (0.1) of the AF film layer can reduce the damage of daily friction to the underlying superhard film, prolonging the service life of the anti-scratch effect;

[0121] Post-treatment stage: ensure product quality consistency;

[0122] Hardness detection principle (Mohs hardness method): use a standard Mohs hardness pen (1~10 levels) to scratch the surface of the substrate from low hardness to high hardness, and determine the hardness according to the scratch situation - if there is no scratch with a 5-level pen and a scratch with a 6-level pen, it is determined to be 5; if there is no scratch with a 6-level pen and a scratch with a 7-level pen, it is determined to be 6, to ensure that the product meets the basic anti-scratch requirements;

[0123] Water drop angle detection principle: the contact angle measuring instrument emits a certain volume of water droplet (5μL) to the surface of the substrate, and captures the water droplet profile through the optical system, calculates the included angle (water drop angle) between the water droplet and the surface - the larger the angle, the better the antifouling effect, the initial ≥115° ensures the initial antifouling performance, and the friction after ≥102° ensures the durability;

[0124] Cutting and edging principle: laser cutting melts the glass substrate by high-energy laser beam (wavelength 532nm / 1064nm), cutting accuracy ±0.1mm, suitable for complex shapes; diamond grinding wheel edging removes the sharp edges after cutting through "diamond particle grinding", and at the same time forms a small fillet (radius 2~5mm) on the edge of the glass, improves the impact resistance (impact strength improves by 20% after edging), and avoids scratching the user's hand when using;

[0125] Coordination principle of each process:

[0126] The "activated substrate" of the pretreatment provides a good bonding basis for multi-layer plating film, avoiding film peeling;

[0127] The "alternating structure" of the multi-layer superhard plating film provides a stable substrate for the AF layer (SiO2 and AF are easy to combine), while ensuring the anti-scratch performance;

[0128] The "antifouling + low friction" of the AF layer not only improves the user experience, but also protects the underlying superhard film, prolonging the service life of the product;

[0129] The "multi-dimensional screening" in the detection stage can eliminate products with insufficient hardness and poor antifouling effect, ensuring the quality consistency of finished products;

[0130] To sum up, the application constructs a cover plate glass processing system of "adapting to multiple sizes, taking into account scratch resistance and stain resistance, and mass production" through the synergistic effect of each process, solves the core pain points of cover plate glass in the fields of smart wear, smart phones and the like, and realizes the dual goals of "basic performance + user experience".

[0131] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for processing and preparing cover glass with super-hard optical coating, characterized in that: The following steps are involved: S1. Pretreatment of the glass substrate: cleaning the glass substrate to remove foreign matter on the surface, followed by plasma treatment to improve surface adhesion; S2. Preparation of a multi-layer superhard coating layer, using an evaporation or sputtering process to deposit multiple layers of alternating superhard coating layers on the surface of the pretreated glass substrate, wherein the multiple layers of alternating superhard coating layers are formed by alternating SiO2 layers and superhard material layers, wherein the superhard material is selected from at least one of DLC, Si3N4, Al2O3, SiAlN, and SiC; S3, AF anti-fingerprint film preparation, using evaporation coating process to coat AF anti-fingerprint film on the surface of multi-layer super-hard coating layer; S4. Post-processing inspection: the hardness, water drop angle and friction number of the plated cover glass are tested. If qualified, it is cut and edged according to needs to obtain the finished product.

2. The method for processing and preparing cover glass with super-hard optical coating according to claim 1, characterized in that: The cleaning treatment in step S1 is conventional water washing or solvent cleaning to ensure that the surface of the glass substrate is free of oil, dust, and the plasma treatment uses Ar gas as the gas source, and generates glow plasma through an ion source to bombard the glass surface, so that the glass surface can reach 28 to 30 dynes.

3. The method for processing and preparing cover glass with super-hard optical coating according to claim 1, characterized in that: The specific structure of the multi-layer alternating superhard coating layer in step S2 is selected from one of the following 11 methods: Sputtering process: SiO2 / DLC / Si3N4 / SiO2 / AF (AF is the product of step S3, the same below); Sputtering process: SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / AF; Sputtering process: SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / DLC / SiO2 / AF; Sputtering process: SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / AF; Sputtering process: SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / Si3N4 / SiO2 / DLC / SiO2 / AF; Sputtering process: SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / AF; Sputtering process: SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / SiAlN / SiO2 / DLC / SiO2 / AF; Sputtering process: SiO2 / Si3N4 / Al2O3 / SiO2 / AF; Sputtering process: SiO2 / Si3N4 / Al2O3 / SiO2 / DLC / SiO2 / AF; Evaporation process: SiC+SiO2 / AF; Evaporation process: SiO2+SiC+SiO2 / AF.

4. The method for processing and preparing cover glass with super-hard optical coating according to claim 1, characterized in that: The total thickness of the multi-layer alternating superhard coating layer in step S2 is 30~75nm, wherein the thickness of a single SiO2 layer is controlled at 5~10nm, and the thickness of a single superhard material layer is controlled at 5~6nm. The film thickness is monitored and controlled in real time by a crystal oscillator.

5. The method for processing and preparing cover glass with super-hard optical coating according to claim 1, characterized in that: The evaporation process in step S2 uses a vacuum vapor deposition (PVD) coating machine, and the vacuum degree of the coating chamber is made to reach 3.0×10⁻ by a molecular pump. 5 ~8.0×10⁻ 5 torr, Ar gas is introduced to prevent oxidation of the film material, and the crucible is heated by a strong current to vaporize SiO2 or superhard material and deposit it on the glass surface; the sputtering process adopts target magnetron sputtering, and the cavity vacuum is maintained by a molecular pump to ensure the adhesion of the film layer.

6. The method for processing and preparing cover glass with super-hard optical coating according to claim 1, characterized in that: The preparation of the AF anti-fingerprint film in step S3 is specifically as follows: placing the AF film material on a molybdenum boat connected to electrodes, heating the molybdenum boat by electric current to evaporate the AF film material, and uniformly adhering to the surface of the multi-layer super-hard coating layer under the action of plasma. The thickness of the AF anti-fingerprint film is controlled to be about 25nm.

7. The method for processing and preparing cover glass with super-hard optical coating according to claim 1, characterized in that: The specific criteria for the detection in step S4 are: The hardness test uses a Mohs hardness pen. When the evaporation process is used, the Mohs hardness is ≥5, and when the sputtering process is used, the Mohs hardness is ≥6; The water drop angle is tested using a contact angle meter. The initial water drop angle is ≥115°. After 2500 friction tests (load 100g), the water drop angle is ≥102°. The friction times are tested by using an eraser friction test, with the friction times ≥ 6300 times (eraser model: 7000N, friction speed 100mm / min).

8. The method for processing and preparing cover glass with super-hard optical coating according to claim 1, characterized in that: The glass substrate is selected from ordinary aluminosilicate glass, microcrystalline glass or ceramic sheet; the applicable size range is 1 inch to 20 inches or above, among which the small-screen touch screen cover glass below 10 inches can adopt evaporation or sputtering process, and the large-screen touch screen cover glass above 20 inches preferably adopts vacuum magnetron sputtering process.

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