CN105141812A - Method for producing sapphire camera window film - Google Patents

Abstract

The invention relates to a production method of a sapphire camera window, and the specific steps include crystal rod removal, crystal cutting, grinding, chamfering, annealing, double-sided polishing, laser slice removal, film coating, ink coating and thermal drying, etc.; The finished camera window film has high quality, low reject rate and high production efficiency.

Description

Production method of sapphire camera window

technical field

The invention relates to a production method of a sapphire sheet, in particular to a production method of a sapphire camera window sheet, and belongs to the technical field of sapphire processing.

Background technique

In modern life, mobile phones have become an indispensable electronic product for people, and most mobile phones have the function of taking pictures. The window covering the camera of a traditional mobile phone to protect the camera is made of glass, which has a Mohs hardness of only 7 and poor wear resistance.

With the advancement of technology, glass mobile phone camera windows are gradually being replaced by sapphire materials. Sapphire has very good thermal properties, excellent electrical properties and dielectric properties, can maintain high strength at high temperatures, excellent thermal properties and transmittance, and is chemically resistant. The mobile phone camera window made of sapphire has high definition, good three-dimensional effect, scratch-resistant surface, and high consumer satisfaction.

Chinese patent document ZL201410294312.8 discloses a method for processing a sapphire material mobile phone window. The specific implementation method is: take the sapphire material and pre-polish it with a laser; laser cut the polished block-shaped sapphire and cut it into pieces , cut into a square block with a designed size for the molding process; trim the edge of the laser-cut wafer into an arc shape to improve the mechanical strength of the edge of the thin slice; roughly grind the chamfered wafer and remove the slice The damage layer caused by the cutting of the wafer and the flatness of the wafer are improved; the rough-ground wafer is shaped with a laser; the waste of the shaped wafer is cut by laser and cut into a predetermined shape. The process design of this method is not reasonable enough, which will directly affect the quality and yield of the window.

Contents of the invention

The technical problem solved by the invention is to propose a production method of a sapphire camera window with high film quality, low rejection rate and high production efficiency.

In order to solve the problems of the technologies described above, the technical solution proposed by the present invention is: a production method of a sapphire camera window, comprising the following specific steps:

Step 1, crystal rod extraction; take the sapphire crystal of A direction, M direction or C direction, and then use the rod removal machine to remove the rod, so as to obtain the crystal rod;

Step 2, crystal cutting: use diamond wire cutting equipment to cut the ingot, so as to obtain the wafer;

Step 3: Grinding; use a grinding machine to grind the wafer; when grinding, add grinding liquid, the grinding disc pressurizes the wafer to 0.02-0.022Mpa, and the speed of the grinding disc is 1000-1200rpm/min; after the grinding is completed, use absolute ethanol Cleaning; the grinding liquid components include: 0.5-2% of cubic boron nitride powder with a particle size of 10-20 μm, 14-16% of alkylphenol polyoxyethylene ether, 4-6% of glycerin, 9- 11% polypropylene glycol 400, the rest is deionized water;

Step 4, chamfering; using a diamond grinding wheel of a numerically controlled machine tool to chamfer the corners of the wafer;

Step 5, annealing; put the wafer into the annealing furnace, raise the temperature to 1600°C at a rate of 180-220°C/h, keep warm at 300°C, 800°C, and 1600°C for 2-6 hours respectively, and then Cool down at 200°C, keep warm at 1000°C and 500°C for 2 to 3 hours, cool to room temperature, and take out;

Step 6, double-sided chemical polishing; first clean the wafer with absolute ethanol, then put the cleaned wafer into a double-sided polishing machine and fix it; when polishing, add polishing liquid, and the polishing disc pressurizes the wafer to 0.12-0.15 Mpa, the rotating speed of the polishing disc is 1000～1500rpm/min, after cleaning the polished wafer with absolute ethanol, it is naturally cooled at room temperature; the polishing liquid components include: 0.5～2% of particles with a particle size of 1～ 6μm cubic boron nitride powder, 14-16% alkylphenol polyoxyethylene ether, 4-6% glycerin, 9-11% polypropylene glycol 400, 0.5-2% nano-silica, making the polishing liquid Alkaline solution with a pH value of 11.0 to 13.0, and the rest is deionized water; during the polishing process, the alkaline solution is continuously replenished to maintain the pH value of the polishing solution;

Step 7. Laser taking slices; put the polished wafer into the laser cutting machine and pass through the protective gas, and cut the wafer into corresponding sizes according to requirements;

Step 8, Coating: use an optical vacuum coating machine to coat the front and back sides of the wafer with an anti-reflection film. The anti-reflection film is formed by layer-by-layer coating of low refractive index oxides and high refractive index oxides, and the number of layers is 4 to 8 layers. , the layer closest to the wafer adopts a low-refractive-index oxide, the low-refractive-index oxide is an oxide of silicon or aluminum, and the high-refractive-index oxide is an oxide of titanium or tantalum;

Step 9, apply ink; cover the coated wafer with a hollow plate, brush the ink on the edge of the wafer and repeat the brushing for three layers;

Step 10. Heat drying; place the ink-coated wafer in a heat dryer for 2-3 hours, and then air-cool to room temperature.

The improvement to the above technical solution is: in the second step, the diameter of the emery wire is 0.14-0.16 mm, the particle size of the diamond on the emery wire is 30-40 μm, and the emery wire moves at a speed of 12-15 m/s during cutting , the moving speed of the crystal relative to the diamond wire is 0.2-0.3 mm/min, and the cutting fluid is continuously sprayed on the diamond wire during cutting, and the cutting fluid contains diamond particles with a particle size of 20-30 μm and diamond particles with a particle size of 50-60 μm. Corundum particles.

The improvement to the above technical solution is: in the third step, the grinding liquid contains alumina particles with a particle size of 3-6 μm.

The improvement to the above technical solution is as follows: in the fifth step, when the temperature is raised, heat preservation at 300° C. for 2 hours, heat preservation at 800° C. for 3 hours, and heat preservation at 1600° C. for 4 hours.

The improvement to the above technical solution is: in the sixth step, the alkaline solution is KOH.

The improvement to the above technical solution is: in the sixth step, the pH value of the polishing liquid is 12.0-13.0.

The improvement to the above technical solution is: in the sixth step, the polishing disc pressurizes the wafer to 0.135Mpa.

The improvement to the above technical solution is: in the seventh step, the diameter of the laser beam is 0.015-0.02 mm, and the cutting speed is 3-5 mm/s.

The improvement to the above technical solution is as follows: in the eighth step, the optical vacuum coating machine uses an ion source to generate an electron beam, firstly liquefies the low-refractive index oxide or high-refractive index oxide and solidifies for pre-melting, and then The solidified low-refractive index oxide or high-refractive index oxide is gasified and sprayed onto the crystal surface to form a film.

The present invention has positive effect:

(1) In the production method of the camera window of the present invention, the production efficiency of grinding and polishing can be improved by first grinding and polishing and then taking the film by laser. Because sapphire has high hardness, a large pressure must be applied during polishing, and annealing before polishing is beneficial Eliminate the internal stress generated by mechanical processing such as wire cutting and grinding, so that the wafer is not suitable for cracking during polishing, and the yield rate is effectively improved.

(2) The camera window production method of the present invention strictly controls the parameters of grinding and polishing as well as the composition of the grinding liquid and polishing liquid, which is beneficial to improving the efficiency of grinding and polishing, improving the yield of grinding and polishing, and the prepared wafer structure Complete, no physical damage, fine and smooth surface, little deformation. In the grinding liquid and polishing liquid, an appropriate amount of cubic boron nitride powder acts as an abrasive, which has high hardness and good wear resistance; the suspension viscosity and interfacial film formed by alkylphenol polyoxyethylene ether, glycerin, polypropylene glycol 400 and deionized water The property is stable, which makes the suspension of the abrasive stable, the uniformity is good, and it will not stick together, which is beneficial to improve the quality and efficiency of grinding and polishing. An appropriate amount of alkylphenol polyoxyethylene ether is a non-ionic surfactant, which is stable in nature and has various properties such as dispersion, emulsification, and wetting. It is the most important component for obtaining excellent performance of the suspension; Both water and organic solutions have good solubility, and are very suitable as an auxiliary dispersant; polypropylene glycol 400 has the functions of emulsification and wetting, and can effectively thicken, effectively improving the viscosity of the suspension and the properties of the interfacial film. In addition, the polishing liquid contains an appropriate amount of nano-SiO ₂ , which has uniform particle size, good dispersion and high planarization efficiency. The alkaline solution KOH makes the polishing liquid alkaline, and assists polishing through chemical corrosion, so that the polishing effect is better and the polishing efficiency is better. In order to maintain the stability of the polishing solution, thereby ensuring the efficiency and quality of polishing, the alkaline solution must be continuously replenished to keep the pH value of the polishing solution basically unchanged.

(3) In the production method of the camera window of the present invention, through the coating process, the light transmittance is increased and the reflectivity is reduced, so that the original 89% light transmittance of the sapphire wafer can be increased to more than 94%. In the coating process, the low-refractive index oxide or high-refractive index oxide is liquefied and then solidified for pre-melting, which can make the distribution of the oxide more uniform and improve the coating effect.

(4) In the production method of the camera window of the present invention, three layers of ink are applied and then dried to make the edge of the wafer opaque, which can effectively prevent light from entering from the side of the wafer and affecting imaging.

(5) The camera window of the present invention is made of sapphire as the base material. Due to the high hardness and good wear resistance of sapphire, the window is not easy to be worn and scratched. The window produced by the camera window production method of the present invention has high smoothness, good light transmittance, up-to-standard optical performance, high film quality, low scrap rate, high production efficiency and broad application prospects.

Detailed ways

Example 1

The preparation process of the sapphire camera window of the present embodiment includes the following steps:

Step 1, crystal rod extraction; take the sapphire crystal of A direction, M direction or C direction, and then use the rod removal machine to remove the rod, so as to obtain the crystal rod;

Step 2, crystal cutting: use diamond wire cutting equipment to cut the ingot, so as to obtain the wafer;

Step 3, grinding; use a grinding machine to grind the wafer; when grinding, add grinding liquid, the grinding disc pressurizes the wafer to 0.022Mpa, and the speed of the grinding disc is 1200rpm/min; after the grinding is completed, clean it with absolute ethanol; The grinding liquid components include: 2% cubic boron nitride powder with a particle size of 20 μm, 16% alkylphenol polyoxyethylene ether, 6% glycerin, 11% polypropylene glycol 400, and the rest is deionized water;

Step 4, chamfering; using a diamond grinding wheel of a numerically controlled machine tool to chamfer the corners of the wafer;

Step 5, annealing; put the wafer into the annealing furnace, raise the temperature to 1600°C at a rate of 220°C/h, keep it at 300°C for 2 hours, keep it at 800°C for 3 hours, and keep it at 1600°C for 4 hours, then Cool down at a temperature of 200°C. During cooling, keep warm at 1000°C and 500°C for 3 hours, cool to room temperature and take out;

Step 6, double-sided chemical polishing; first clean the wafer with absolute ethanol, then put the cleaned wafer into a double-sided polishing machine and fix it; when polishing, add polishing liquid, and the polishing disc pressurizes the wafer to 0.15Mpa, The rotating speed of the polishing disc is 1500rpm/min, after cleaning the polished wafer with absolute ethanol, it is cooled naturally at room temperature; the polishing liquid components include: 2% cubic boron nitride powder with a particle size of 6 μm, 14-16% of alkylphenol polyoxyethylene ether, 6% of glycerin, 11% of polypropylene glycol 400, 2% of nano-silicon dioxide, making the polishing liquid an alkaline solution with a pH value of 13.0, and the rest is deionized water ; During the polishing process, the alkaline solution is continuously replenished to maintain the pH value of the polishing solution;

Step 7. Laser taking slices; put the polished wafer into the laser cutting machine and pass through the protective gas, and cut the wafer into corresponding sizes according to requirements;

Step 8, coating; adopt optical vacuum coating machine to coat anti-reflection film on both sides of wafer, anti-reflection film is formed by layer-by-layer coating of low refractive index oxide and high refractive index oxide and the number of layers is 8 layers, finally A layer close to the wafer adopts a low-refractive-index oxide, the low-refractive-index oxide is an oxide of silicon or aluminum, and the high-refractive-index oxide is an oxide of titanium or tantalum;

Step 9, apply ink; cover the coated wafer with a hollow plate, brush the ink on the edge of the wafer and repeat the brushing for three layers;

Step 10. Heat drying; place the ink-coated wafer in a heat dryer for 2-3 hours, and then air-cool to room temperature.

Example 2

The preparation process of the sapphire camera window of the present embodiment includes the following steps:

Step 1, crystal rod extraction; take the sapphire crystal of A direction, M direction or C direction, and then use the rod removal machine to remove the rod, so as to obtain the crystal rod;

Step 2, crystal cutting: use diamond wire cutting equipment to cut the ingot, so as to obtain the wafer;

Step 3, grinding; use a grinding machine to grind the wafer; when grinding, add grinding liquid, the grinding disc pressurizes the wafer to 0.02Mpa, and the speed of the grinding disc is 1000rpm/min; after the grinding is completed, clean it with absolute ethanol; The grinding liquid components include: 0.5% cubic boron nitride powder with a particle size of 10 μm, 14% alkylphenol polyoxyethylene ether, 4% glycerin, 9% polypropylene glycol 400, and the rest is deionized water;

Step 4, chamfering; using a diamond grinding wheel of a numerically controlled machine tool to chamfer the corners of the wafer;

Step 5, annealing; put the wafer into the annealing furnace, raise the temperature to 1600°C at a rate of 180°C/h, keep it at 300°C for 2 hours, keep it at 800°C for 4 hours, and keep it at 1600°C for 5 hours, then Cool down at a temperature of 200°C, keep warm at 1000°C and 500°C for 2 hours, cool to room temperature, and take out;

Step 6, double-sided chemical polishing; first clean the wafer with absolute ethanol, then put the cleaned wafer into a double-sided polishing machine and fix it; when polishing, add polishing liquid, and the polishing disc pressurizes the wafer to 0.12Mpa, The rotating speed of the polishing disc is 1000rpm/min, after cleaning the polished wafer with absolute ethanol, it is cooled naturally at room temperature; the polishing liquid components include: 0.5% cubic boron nitride powder with a particle size of 1 μm, 14% of alkylphenol polyoxyethylene ether, 4% of glycerin, 9% of polypropylene glycol 400, 0.5% of nano-silicon dioxide, so that the pH value of the polishing solution is an alkaline solution of 11.0, and the rest is deionized water; polishing During the process, the alkaline solution is constantly replenished to maintain the pH value of the polishing solution;

Step 7. Laser taking slices; put the polished wafer into the laser cutting machine and pass through the protective gas, and cut the wafer into corresponding sizes according to requirements;

Step 8, coating; adopt optical vacuum coating machine to coat anti-reflection film on both sides of wafer, anti-reflection film is formed by layer-by-layer coating of low refractive index oxide and high refractive index oxide and the number of layers is 4 layers, finally A layer close to the wafer adopts a low-refractive-index oxide, the low-refractive-index oxide is an oxide of silicon or aluminum, and the high-refractive-index oxide is an oxide of titanium or tantalum;

Step 9, apply ink; cover the coated wafer with a hollow plate, brush the ink on the edge of the wafer and repeat the brushing for three layers;

Step 10, heat drying; place the ink-coated wafer in a heat dryer for 2 hours, then air cool to room temperature.

Example 3

The preparation process of the sapphire camera window of the present embodiment includes the following steps:

Step 1, crystal rod extraction; take the sapphire crystal of A direction, M direction or C direction, and then use the rod removal machine to remove the rod, so as to obtain the crystal rod;

Step 2, crystal cutting: use diamond wire cutting equipment to cut the ingot, so as to obtain the wafer;

Step 3, grinding; using a grinding machine to grind the wafer; when grinding, add grinding liquid, the grinding disc pressurizes the wafer to 0.02Mpa, and the speed of the grinding disc is 11000rpm/min; after the grinding is completed, clean it with absolute ethanol; The grinding liquid components include: 1% cubic boron nitride powder with a particle size of 15 μm, 15% alkylphenol polyoxyethylene ether, 5% glycerin, 10% polypropylene glycol 400, and the rest is deionized water;

Step 4, chamfering; using a diamond grinding wheel of a numerically controlled machine tool to chamfer the corners of the wafer;

Step 5, annealing; put the wafer into the annealing furnace, raise the temperature to 1600°C at a rate of 200°C/h, keep it at 300°C for 2 hours, keep it at 800°C for 3 hours, and keep it at 1600°C for 5 hours, then Cool down at a temperature of 200°C, keep warm at 1000°C and 500°C for 2 hours, cool to room temperature, and take out;

Step 6, double-sided chemical polishing; first clean the wafer with absolute ethanol, then put the cleaned wafer into a double-sided polishing machine and fix it; when polishing, add polishing liquid, and the polishing disc pressurizes the wafer to 0.13Mpa, The rotating speed of the polishing disc is 1200rpm/min, after cleaning the polished wafer with absolute ethanol, it is cooled naturally at room temperature; the polishing liquid components include: 1% cubic boron nitride powder with a particle size of 3 μm, 15% of alkylphenol polyoxyethylene ether, 5% of glycerin, 10% of polypropylene glycol 400, 1% of nano-silicon dioxide, so that the pH value of the polishing solution is an alkaline solution of 12.0, and the rest is deionized water; polishing During the process, the alkaline solution is constantly replenished to maintain the pH value of the polishing solution;

Step 7. Laser taking slices; put the polished wafer into the laser cutting machine and pass through the protective gas, and cut the wafer into corresponding sizes according to requirements;

Step 8, coating; adopt optical vacuum coating machine to coat anti-reflection film on both sides of wafer, anti-reflection film is formed by layer-by-layer coating of low refractive index oxide and high refractive index oxide and the number of layers is 6 layers, finally A layer close to the wafer adopts a low-refractive-index oxide, the low-refractive-index oxide is an oxide of silicon or aluminum, and the high-refractive-index oxide is an oxide of titanium or tantalum;

Step 9, apply ink; cover the coated wafer with a hollow plate, brush the ink on the edge of the wafer and repeat the brushing for three layers;

Step 10, heat drying; place the ink-coated wafer in a heat dryer for 3 hours, then air cool to room temperature.

The production method of the sapphire camera window of the present invention is not limited to the specific technical solutions described in the above embodiments, and any technical solutions formed by equivalent replacement are within the scope of protection required by the present invention.

Claims (9)

1. a production method of sapphire camera window, is characterized in that, comprises the following concrete steps: Step 1, crystal rod extraction; take the sapphire crystal of A direction, M direction or C direction, and then use the rod removal machine to remove the rod, so as to obtain the crystal rod; Step 2, crystal cutting: use diamond wire cutting equipment to cut the ingot, so as to obtain the wafer; Step 3: Grinding; use a grinding machine to grind the wafer; when grinding, add grinding liquid, the grinding disc pressurizes the wafer to 0.02-0.022Mpa, and the speed of the grinding disc is 1000-1200rpm/min; after the grinding is completed, use absolute ethanol Cleaning; the grinding liquid components include: 0.5-2% of cubic boron nitride powder with a particle size of 10-20 μm, 14-16% of alkylphenol polyoxyethylene ether, 4-6% of glycerin, 9- 11% polypropylene glycol 400, the rest is deionized water; mix; Step 4, chamfering; using the diamond grinding wheel of the CNC machine tool to chamfer the corners of the wafer; Step 5, annealing; put the wafer into the annealing furnace, raise the temperature to 1600°C at a rate of 180-220°C/h, keep warm at 300°C, 800°C, and 1600°C for 2-6 hours respectively, and then Cool down at 200°C, keep warm at 1000°C and 500°C for 2 to 3 hours, cool to room temperature, and take out; Step 6, double-sided chemical polishing; first clean the wafer with absolute ethanol, then put the cleaned wafer into a double-sided polishing machine and fix it; when polishing, add polishing liquid, and the polishing disc pressurizes the wafer to 0.12-0.15 Mpa, the rotating speed of the polishing disc is 1000～1500rpm/min, after cleaning the polished wafer with absolute ethanol, it is naturally cooled at room temperature; the polishing liquid components include: 0.5～2% of particles with a particle size of 1～ 6μm cubic boron nitride powder, 14-16% alkylphenol polyoxyethylene ether, 4-6% glycerin, 9-11% polypropylene glycol 400, 0.5-2% nano-silica, making the polishing liquid Alkaline solution with a pH value of 11.0 to 13.0, and the rest is deionized water; during the polishing process, the alkaline solution is continuously replenished to maintain the pH value of the polishing solution; Step 7. Laser taking slices; put the polished wafer into the laser cutting machine and pass through the protective gas, and cut the wafer into corresponding sizes according to requirements; Step 8, Coating: use an optical vacuum coating machine to coat the front and back sides of the wafer with an anti-reflection film. The anti-reflection film is formed by layer-by-layer coating of low refractive index oxides and high refractive index oxides, and the number of layers is 4 to 8 layers. , the layer closest to the wafer adopts a low-refractive-index oxide, the low-refractive-index oxide is an oxide of silicon or aluminum, and the high-refractive-index oxide is an oxide of titanium or tantalum; Step 9, apply ink; cover the coated wafer with a hollow plate, brush the ink on the edge of the wafer and repeat the brushing for three layers; Step 10. Heat drying; place the ink-coated wafer in a heat dryer for 2-3 hours, and then air-cool to room temperature. 2. according to the production method of the described sapphire camera window of claim 1, it is characterized in that: in described step 2, the diameter of emery wire is 0.14～0.16mm, and the particle diameter of diamond on emery line is 30～40 μ m, and the diameter of emery wire is 30～40 μm, and When cutting, it moves at a speed of 12-15m/s. The moving speed of the crystal relative to the emery wire is 0.2-0.3mm/min. During cutting, the cutting fluid is continuously sprayed on the emery wire. The cutting fluid contains a particle size of 20- 30 μm diamond particles and corundum particles with a particle size of 50-60 μm. 3. The production method of the sapphire camera window according to claim 1, characterized in that: in the third step, the grinding liquid contains alumina particles with a particle size of 3-6 μm. 4. The production method of the sapphire camera window according to claim 1, characterized in that: in the step 5, when the temperature is raised, it is kept at 300° C. for 2 hours, at 800° C. for 3 hours, and at 1600° C. for 4 hours. 5. The production method of the sapphire camera window according to claim 1, characterized in that: in the step six, the alkaline solution is KOH. 6. The production method of the sapphire camera window according to claim 1, characterized in that: in the sixth step, the pH value of the polishing solution is 12.0. 7. The production method of the sapphire camera window according to claim 1, characterized in that: in the sixth step, the polishing disc pressurizes the wafer to 0.135Mpa. 8 . The production method of the sapphire camera window according to claim 1 , characterized in that: in the seventh step, the diameter of the laser beam is 0.015-0.02 mm, and the cutting speed is 3-5 mm/s. 9. according to the production method of the described sapphire camera window of claim 1, it is characterized in that: in described step 8, described optical vacuum coater, adopt ion source to generate electron beam, first low refractive index oxide or high refractive index After liquefaction, the high-refractive oxides are solidified and pre-melted, and then the solidified low-refractive-index oxides or high-refractive-index oxides are vaporized and sprayed onto the crystal surface to form a film.