Method for manufacturing free-form random metallic texture

Abstract

The application relates to a free curved surface random metal texture manufacturing method, which comprises the following steps: forming a photoresist film on a water-drop-shaped free curved surface substrate after ultrasonic cleaning; determining pre-prepared texture pattern information, obtaining visual image information of the water-drop-shaped free curved surface substrate after baking and solidifying the photoresist, analyzing the visual image information and the pre-prepared texture pattern information, determining a laser motion track, and using the laser motion track to control the laser to perform an exposure operation on the water-drop-shaped free curved surface substrate after baking and solidifying the photoresist according to the pre-prepared texture pattern information; developing the water-drop-shaped free curved surface substrate after exposure; performing vacuum evaporation film plating on the water-drop-shaped free curved surface substrate after development; removing the photoresist on the water-drop-shaped free curved surface substrate after film plating; and using a high-precision visual system and a pre-programmed spatial outward expansion curved surface track to ensure that the laser is accurately exposed according to the pre-prepared texture pattern information, so that the deviation problem caused by insufficient repeated precision is reduced.

Description

Technical Field

[0001] This invention relates to the technical field of creating random metal textures on freeform surfaces, and in particular to a method for creating random metal textures on freeform surfaces. Background Technology

[0002] Currently, laser direct writing technology is widely used in the fields of micro / nano manufacturing and precision engineering due to its high resolution and flexibility in fabricating complex micron- or nanoscale structures. However, for the processing of curved substrates, especially in applications requiring multiple scanning etching, this technology faces a severe challenge in terms of repeatability accuracy. Specifically, the requirement of at least two scanning etching operations on curved surfaces places particularly stringent demands on the accuracy and stability of laser direct writing equipment. During multiple scans, even minute mechanical deviations or alignment errors can lead to significant misalignments. These misalignments accumulate and amplify, ultimately affecting the geometric accuracy and functional performance of the product, thus limiting the application scope of laser direct writing technology in high-precision curved surface processing. Summary of the Invention

[0003] To address the issue of high probability of misalignment during multiple scanning and etching processes using laser direct writing equipment in traditional fabrication methods, this application provides a method for creating random metal textures on freeform surfaces.

[0004] A method for creating random metal textures on freeform surfaces, comprising:

[0005] S11, Ultrasonic cleaning of teardrop-shaped freeform surface substrates.

[0006] S12. Photoresist is coated onto a teardrop-shaped freeform substrate after ultrasonic cleaning.

[0007] S13. Bake the photoresist-coated teardrop-shaped freeform substrate to solidify the photoresist.

[0008] S14. Determine the pre-made texture pattern information. Based on the pre-made texture pattern information, obtain the visual image information of the water droplet-shaped freeform surface substrate after baking and solidifying the adhesive. Analyze the visual image information and the pre-made texture pattern information to determine the laser motion trajectory. The laser motion trajectory is used to control the laser to perform exposure operation on the water droplet-shaped freeform surface substrate after baking and solidifying the adhesive according to the pre-made texture pattern information.

[0009] S15. Develop the exposed teardrop-shaped freeform substrate;

[0010] S16. Vacuum evaporation coating is performed on the developed teardrop-shaped freeform surface substrate;

[0011] S17. Remove the adhesive from the coated teardrop-shaped freeform surface substrate;

[0012] S18. Ultrasonic cleaning of the teardrop-shaped freeform substrate after adhesive removal.

[0013] S19. Transfer the cleaned and degummed teardrop-shaped freeform substrate to a projection optical imager for texture measurement.

[0014] By employing the aforementioned technical solution, the laser's trajectory is determined by analyzing the pre-fabricated texture pattern information and the visual image information of the teardrop-shaped freeform substrate after baking and solidification. This step utilizes a high-precision vision system and a pre-programmed spatial outward-expanding surface trajectory to ensure precise laser exposure according to the pre-fabricated texture pattern information, thereby reducing misalignment issues caused by insufficient repeatability. This method achieves precise exposure of the freeform substrate by accurately controlling the laser's trajectory, avoiding misalignment during multiple scanning etching processes and improving manufacturing accuracy and repeatability. Furthermore, through subsequent development, vacuum evaporation coating, and resist removal steps, this method can form uniform and precise metal textures on the freeform substrate. Finally, ultrasonic cleaning and optical imaging measurements ensure texture quality, achieving high-quality freeform random metal texture fabrication. This not only improves product performance and reliability but also enhances the stability and efficiency of the manufacturing process.

[0015] Preferably, in step S12, a photoresist film is coated on the water droplet-shaped freeform surface substrate after ultrasonic cleaning by an ultrasonic coating mechanism. The ultrasonic coating mechanism includes a control box, a first motion system, a contour heating base and a support frame located on the control box. The first motion system is equipped with an ultrasonic nozzle and the support frame is equipped with a vision system.

[0016] Step 12 also includes the following steps:

[0017] Based on a vision system, obtain the motion coordinate system of a teardrop-shaped freeform surface substrate;

[0018] Determine the preset three-dimensional trajectory;

[0019] Based on the preset three-dimensional trajectory and the motion coordinate system, the first motion system is controlled to perform a coating operation on the teardrop-shaped freeform surface substrate located in the contour heating base.

[0020] By adopting the above technical solution, the technical effect of using the ultrasonic coating mechanism in step S12 is that, with the assistance of a precise vision system and the control of the first motion system, uniform film coating of photoresist on a teardrop-shaped freeform substrate is achieved, ensuring the quality and precision of subsequent photolithography processes. At the same time, the application of the contour heating base effectively avoids the problem of inconsistent coating thickness caused by the shape of the substrate or gravity.

[0021] Preferably, the contour heating base is provided with a controllable heating flexible cloth, and before performing step S12, the following steps are also included:

[0022] Determine whether the temperature parameters of the controllable heating flexible fabric have reached a preset threshold;

[0023] If so, a first window will be pushed to prompt the ultrasonic coating mechanism to start photoresist film coating;

[0024] If not, a second window will be pushed to indicate that the conditions for starting the ultrasonic coating mechanism to form a photoresist film are not met, and an audible and visual alarm will be triggered.

[0025] By adopting the above technical solution, this technology integrates a controllable heating flexible cloth on the contour heating base and performs preset threshold detection of temperature parameters before coating photoresist, ensuring that the substrate is coated with photoresist under optimal temperature conditions, thereby improving film quality and process reliability. At the same time, intuitive window prompts and audible and visual alarm mechanisms enhance the controllability and safety of the process.

[0026] Preferably, the preset threshold is 30±2℃.

[0027] By adopting the above technical solution and setting a preset threshold of 30±2℃, this technology ensures the temperature control accuracy of the substrate before photoresist coating, thereby optimizing the film formation effect of photoresist, improving the uniformity and adhesion of the coating, and reducing process defects caused by temperature fluctuations.

[0028] Preferably, in step S14, the laser system and the second motion system are used to cover the surface of the teardrop-shaped freeform substrate with the texture pattern corresponding to the pre-made texture pattern information to complete the exposure operation;

[0029] The laser system uses a dmd spatial light modulator and a beam shaping lens group to determine pre-fabricated texture micro-units, and projects the pre-fabricated texture micro-units onto a small light curtain onto a teardrop-shaped freeform surface substrate.

[0030] By adopting the above technical solution, the technology used in step S14 achieves high-resolution and high-precision texture pattern exposure by precisely controlling the coordinated operation of the laser system and the second motion system, combined with the DMD spatial light modulator and beam shaping lens group. This ensures that the pre-made texture micro-units can be uniformly and accurately projected and covered on the entire teardrop-shaped freeform surface substrate, thereby giving it a predetermined functional texture pattern while maintaining the original characteristics of the surface.

[0031] Preferably, the wavelength of the laser source in the laser system is 375±10nm.

[0032] By adopting the above technical solution and selecting a laser light source with a wavelength of 375±10nm, this technology achieves precise absorption and processing of specific materials, while minimizing the heat-affected zone, effectively avoiding unnecessary damage to the teardrop-shaped freeform substrate, and ensuring the precision of micro-nano structure processing and the integrity of the substrate material.

[0033] Preferably, in step S15, the stripping solution is sprayed onto the surface of the droplet-shaped freeform substrate for development. The thickness of the micron-sized thin film coating formed after the solvent in the photoresist evaporates will vary at different times during the development process. The development time is defined by determining the different photoresist materials and the thickness difference of the micron-sized thin film coating.

[0034] In step 17, the stripping solution is sprayed onto the surface of the teardrop-shaped freeform substrate to remove the photoresist. The thickness of the micron-sized thin film coating formed after the solvent in the photoresist evaporates will vary at different times during the stripping process. The stripping operation time is defined by determining the different photoresist materials and the thickness difference of the micron-sized thin film coating.

[0035] By adopting the above technical solution, and by precisely controlling the spraying of the stripping solution during the development and stripping processes, combined with real-time monitoring of different photoresist materials and micron-sized thin film coating thickness, this technology achieves precise definition of the development and stripping operation time, ensuring uniform removal of the photoresist coating and accurate transfer of micron-sized patterns, thereby optimizing the accuracy and repeatability of the entire photolithography process.

[0036] Preferably, step S16 includes the following steps:

[0037] The developed teardrop-shaped freeform surface substrate is clamped in a rotating tooling fixture;

[0038] An RF ion source was used to perform surface bombardment cleaning on a teardrop-shaped freeform substrate clamped in a self-rotating fixture according to a preset operation time.

[0039] A chromium film, a copper film, another chromium film, another copper film, and a final chromium film are sequentially deposited on the surface of a teardrop-shaped freeform substrate.

[0040] By adopting the above technical solution, the technology used in step S16 fixes the developed teardrop-shaped freeform surface substrate in a rotating tooling fixture, uses an RF ion source for surface bombardment cleaning, and then precisely vapor-deposits multiple alternating layers of chromium and copper films, achieving the deposition of a uniform and high-quality electromagnetic shielding layer, while ensuring the precise alignment and cleanliness of the substrate, thus improving the performance and reliability of the final product.

[0041] A method for creating random metallic textures on freeform surfaces, the method comprising:

[0042] S21, Ultrasonic cleaning of teardrop-shaped freeform surface substrates.

[0043] S22. Vacuum evaporation coating is performed on the water droplet-shaped freeform surface substrate after ultrasonic cleaning.

[0044] S23. Coat a photoresist film onto the water droplet-shaped freeform substrate after coating;

[0045] S24. Bake the photoresist-coated teardrop-shaped freeform substrate to solidify the photoresist.

[0046] S25. Determine the pre-made texture pattern information. Based on the pre-made texture pattern information, obtain the visual image information of the water droplet-shaped freeform surface substrate after baking and solidifying the adhesive. Analyze the visual image information and the pre-made texture pattern information to determine the laser motion trajectory. The laser motion trajectory is used to control the laser to perform exposure operation on the water droplet-shaped freeform surface substrate after baking and solidifying the adhesive according to the pre-made texture pattern information.

[0047] S26. Develop the exposed teardrop-shaped freeform substrate;

[0048] S27. Etch the developed teardrop-shaped freeform surface substrate;

[0049] S28. Remove the adhesive from the etched teardrop-shaped freeform surface substrate.

[0050] S29. Ultrasonic cleaning of the teardrop-shaped freeform substrate after adhesive removal;

[0051] S210: Transfer the cleaned and degummed teardrop-shaped freeform substrate to a projection optical imager for texture measurement.

[0052] By adopting the above technical solution, the technical effect of the freeform surface random metal texture production method is that, through a series of finely controlled steps such as ultrasonic cleaning, vacuum evaporation coating, photoresist coating and baking, precise laser exposure, development etching, photoresist removal and ultrasonic cleaning, uniform, precise random metal texture with predetermined electromagnetic shielding characteristics is produced on a teardrop-shaped freeform surface substrate. At the same time, the integrity of the substrate and optical performance are ensured. Finally, the texture is measured by an optical imager to verify the product quality.

[0053] Preferably, step S26 includes:

[0054] The etching solution is sprayed onto the developed droplet-shaped freeform substrate, the etching solution being used to simultaneously etch chromium and copper;

[0055] The etched teardrop-shaped freeform substrate is then dried.

[0056] By adopting the above technical solution, the technical effect in step S26 is that the chromium and copper layers on the developed teardrop-shaped freeform substrate are removed simultaneously by spraying etching solution, thereby achieving precise metal layer pattern transfer. The subsequent drying process ensures the cleanliness of the substrate and the smooth progress of subsequent processes, thus giving the substrate the required functional texture while maintaining the surface characteristics.

[0057] In summary, this application includes at least one of the following beneficial technical effects:

[0058] 1. By determining the pre-made texture pattern information and combining it with the visual image information of the teardrop-shaped freeform surface substrate after baking and solidification, the laser's trajectory is determined. This step utilizes a high-precision vision system and a pre-programmed spatial outward-expanding surface trajectory to ensure that the laser is precisely exposed according to the pre-made texture pattern information, thereby reducing the deviation problem caused by insufficient repeatability. This method achieves precise exposure of the freeform surface substrate by precisely controlling the laser's trajectory, avoiding deviations that occur during multiple scanning etching processes, and improving manufacturing accuracy and repeatability. Furthermore, through subsequent development, vacuum evaporation coating, and resist removal steps, this method can form a uniform and precise metal texture on the freeform surface substrate. Finally, ultrasonic cleaning and optical imager measurement ensure the texture quality, achieving high-quality freeform surface random metal texture production; this not only improves product performance and reliability but also enhances the stability and efficiency of the manufacturing process.

[0059] 2. By coordinating the laser system with the second motion system, the laser exposure process can be precisely controlled, as can the spraying of the stripping solution during the development and stripping steps, thus reducing damage to the substrate caused by laser energy. In particular, by using a DMD spatial light modulator and beam-shaping lens group to determine the pre-fabricated texture micro-units and precisely project them onto the substrate, efficient use of laser energy can be ensured, avoiding unnecessary high-energy input. Furthermore, selecting a suitable laser source wavelength (such as the 375±10nm wavelength mentioned in step S16) can reduce the thermal impact of the laser on the substrate material, thereby reducing thermal stress and surface damage. These measures protect the integrity of the substrate, maintain its imaging quality and structural strength, and solve the problem that curved electromagnetic shielding substrates are laser-transparent, and that while removing the curved metal coating, the laser will transmit to the other side of the curved surface, damaging the grid on the other side, and that high-energy laser etching will cause irreparable surface damage and changes in the substrate's internal stress, affecting the imaging quality and strength of the curved surface. Attached Figure Description

[0060] Figure 1 This is a three-dimensional structural schematic diagram of the ultrasonic coating mechanism in one embodiment of this application.

[0061] Explanation of reference numerals in the attached figures

[0062] 1. Control box; 2. First motion system; 3. Contouring heating base; 4. Support frame; 5. Ultrasonic nozzle; 6. Camera; 7. Telecentric lens; 8. Area array light source; 9. Teardrop-shaped freeform surface substrate. Detailed Implementation

[0063] The present application will be further described in detail below with reference to the accompanying drawings.

[0064] Example 1:

[0065] A method for creating random metal textures on freeform surfaces, comprising:

[0066] S11, Ultrasonic cleaning of teardrop-shaped freeform surface substrate 9.

[0067] S12. Photoresist is coated onto the teardrop-shaped freeform substrate 9 after ultrasonic cleaning.

[0068] S13. Bake the teardrop-shaped freeform substrate 9 after the photoresist film is coated to solidify the photoresist;

[0069] S14. Determine the pre-made texture pattern information. Based on the pre-made texture pattern information, obtain the visual image information of the water droplet-shaped freeform surface substrate 9 after baking and solidifying the adhesive. Analyze the visual image information and the pre-made texture pattern information to determine the laser motion trajectory. The laser motion trajectory is used to control the laser to perform exposure operation on the water droplet-shaped freeform surface substrate 9 after baking and solidifying the adhesive according to the pre-made texture pattern information.

[0070] S15. Develop the exposed teardrop-shaped freeform substrate 9.

[0071] S16. Vacuum evaporation coating is performed on the developed teardrop-shaped freeform surface substrate 9.

[0072] S17. Remove the adhesive from the coated teardrop-shaped freeform surface substrate 9.

[0073] S18, Water droplet-shaped freeform substrate 9 after ultrasonic cleaning and degumming.

[0074] S19. Transfer the cleaned and degummed teardrop-shaped freeform substrate 9 to a projection optical imager for texture measurement.

[0075] In this embodiment, step S11 involves ultrasonic cleaning of the teardrop-shaped freeform substrate 9.

[0076] In step S12, a vision-guided robotic arm, equipped with an ultrasonic spray gun, coats the teardrop-shaped freeform substrate 9 with photoresist. The vision system utilizes a 2000W camera 6 and a telecentric lens 7. The teardrop-shaped freeform substrate 9 is fixed to a contour-following base, which is covered with a high-precision, temperature-uniform, and controllable heating flexible cloth. Before coating, the temperature control heating function is activated, and the coating process is initiated only after the temperature display stabilizes. This base significantly reduces the problem of inconsistent photoresist thickness across different areas of the teardrop-shaped freeform substrate 9 due to gravity and the low viscosity of the photoresist. After acquiring the accurate coordinates of the teardrop-shaped freeform substrate 9 through vision, the robotic arm moves according to a pre-programmed 3D trajectory to perform the coating operation. The operating parameters are as follows: robotic arm movement speed 10mm / s, contour base temperature 30℃, spray gun distance from the normal of the teardrop-shaped freeform surface 45mm, photoresist viscosity 1~2cps, ultrasonic frequency 5000kHz, liquid supply flow rate 1.8L / h, using a micro airflow of ≤0.15MPA to guide the flow, so that the photoresist falls evenly onto the substrate to be sprayed, and the solvent evaporates to form a micron-sized thin film coating.

[0077] In step S13, the teardrop-shaped freeform substrate 9 after photoresist film formation is transferred to a clean, constant-temperature oven for baking and curing.

[0078] In step S14, the laser direct-write lithography equipment employs a dual-axis cradle turntable (A-axis and C-axis) combined with a three-linear-axis (X-axis, Y-axis, and Z-axis) configuration. The laser direct-write head is fixed on the X-axis and Z-axis cross-shaped modules, while the dual-axis cradle turntable (A-axis and C-axis) is fixed on the Y-axis. Simultaneously, a 2000W pixel camera 6 with a telecentric lens 7 is fixed on the Z-axis for vision. After obtaining the accurate coordinate system of the teardrop-shaped freeform substrate 9 through vision, the five axes can move according to a pre-programmed spatial outward-expanding surface trajectory. The laser source uses a wavelength of 375±10nm. The laser system projects pre-fabricated texture micro-units onto the teardrop-shaped freeform substrate 9 through a DMD spatial light modulator and a special beam-shaping lens group. Exposure is completed when the pre-fabricated texture pattern is spread across the entire surface of the teardrop-shaped freeform substrate 9 through the coordinated operation of the laser system and the motion system.

[0079] In step S15, the exposed product is fixedly placed on a developing device with a contoured vacuum adsorption rotating shaft. The rotating shaft speed is adjusted to 30-40 rpm, and the developing solution is simultaneously sprayed onto the surface of the teardrop-shaped freeform substrate 9 for development. The development time will vary depending on the photoresist material and the thickness of the micron-sized film layer; the development time can be customized on the device. After development, the spray automatically shuts off, and the rotating shaft speed jumps to 200-300 rpm for spin drying. The entire process is controlled by a microcomputer program; different production formulas can be used for different products.

[0080] In step S16, the developed product is clamped onto a specific tooling fixture with an on-board rotation to fabricate the electromagnetic shielding metal layer. A vacuum evaporation deposition method is used, with surface bombardment cleaning using an RF ion source for 10 minutes. The deposition process involves sequentially depositing a 15nm chromium film, a 100nm copper film, another 15nm chromium film, another 100nm copper film, and another 15nm chromium film. The process parameters are: vacuum chamber vacuum degree 3.0×10³ Pa, vacuum chamber temperature 200°C, on-board rotation speed 20 r / min, vacuum holding time 30 min, followed by room temperature stress release and a 1-hour resting time.

[0081] In step S17, the fabricated electromagnetic shielding teardrop-shaped freeform surface is placed on a photoresist stripping device with a contour-following vacuum adsorption rotating shaft. The rotating shaft is turned on and its speed adjusted to 30-40 rpm, simultaneously spraying the photoresist stripping solution onto the surface of the teardrop-shaped freeform surface substrate 9 for stripping. The stripping time will vary depending on the photoresist material and the thickness of the micron-sized film layer; the stripping time can be customized on the device. After stripping is complete, the spray is automatically turned off, and the rotating shaft speed jumps to 200-300 rpm for spin drying. The entire process is controlled by a microcomputer program; different production formulas can be added for different products.

[0082] In step S18, the degummed product is placed in an ultrasonic cleaning tank to clean off any remaining degumming liquid. At this point, the teardrop-shaped freeform optical cover with electromagnetic shielding function and extremely low diffraction is completed.

[0083] In step S19, the texture is measured under a projection optical imager. The line width of the texture is 5 μm, and the overall appearance of the texture is free from defects such as deformation, broken lines, and missing corners.

[0084] In summary, by determining the pre-fabricated texture pattern information and combining it with the visual image information of the teardrop-shaped freeform substrate 9 after baking and solidification, the laser's trajectory is determined. This step utilizes a high-precision vision system and a pre-programmed spatial outward-expanding surface trajectory to ensure precise laser exposure according to the pre-fabricated texture pattern information, thereby reducing misalignment issues caused by insufficient repeatability. This method achieves precise exposure of the freeform substrate by accurately controlling the laser's trajectory, avoiding misalignment during multiple scanning etching processes and improving manufacturing accuracy and repeatability. Furthermore, through subsequent development, vacuum evaporation coating, and resist removal steps, this method can form uniform and precise metal textures on the freeform substrate. Finally, ultrasonic cleaning and optical imaging measurements ensure texture quality, achieving high-quality freeform random metal texture fabrication. This not only improves product performance and reliability but also enhances the stability and efficiency of the manufacturing process.

[0085] Further, in step S12, photoresist film is coated on the water droplet-shaped freeform surface substrate 9 after ultrasonic cleaning by an ultrasonic coating mechanism. The ultrasonic coating mechanism includes a control box 1, a first motion system 2, a contour heating base 3 and a support frame 4 located on the control box 1. The first motion system 2 is provided with an ultrasonic nozzle 5. The support frame 4 is provided with a vision system corresponding to the contour heating base 3 and an area array light source 8 corresponding to the contour heating base 3. The vision system includes a camera 6 and a telecentric lens 7 located on the camera 6.

[0086] Step 12 also includes the following steps:

[0087] Based on the vision system, the motion coordinate system of the teardrop-shaped freeform surface base 9 is obtained;

[0088] Determine the preset three-dimensional trajectory;

[0089] Based on the preset three-dimensional trajectory and the motion coordinate system, the first motion system 2 is controlled to perform a coating operation on the teardrop-shaped freeform surface substrate 9 located in the contour heating base 3.

[0090] In summary, the technical effect of using the ultrasonic coating mechanism in step S12 is that, with the assistance of a precise vision system and the control of the first motion system 2, uniform film coating of photoresist on the teardrop-shaped freeform substrate 9 is achieved, ensuring the quality and precision of subsequent photolithography processes. At the same time, the application of the contour heating base 3 effectively avoids the problem of inconsistent coating thickness caused by the shape of the substrate or gravity.

[0091] Furthermore, the contour heating base 3 is provided with a controllable heating flexible cloth, and before performing step S12, the following steps are also included:

[0092] Determine whether the temperature parameters of the controllable heating flexible fabric have reached a preset threshold;

[0093] If so, a first window will be pushed to prompt the ultrasonic coating mechanism to start photoresist film coating;

[0094] If not, a second window will be pushed to indicate that the conditions for starting the ultrasonic coating mechanism to form a photoresist film are not met, and an audible and visual alarm will be triggered.

[0095] In summary, this technology, by integrating a controllable heating flexible cloth on the contour heating base 3 and performing preset threshold detection of temperature parameters before photoresist coating, ensures that the substrate is coated with photoresist under optimal temperature conditions, thereby improving film quality and process reliability. At the same time, intuitive window prompts and audible and visual alarm mechanisms enhance the controllability and safety of the process.

[0096] Furthermore, the preset threshold is 30±2℃.

[0097] In summary, by setting a preset threshold of 30±2℃, this technology ensures the temperature control accuracy of the substrate before photoresist coating, thereby optimizing the photoresist film formation effect, improving the uniformity and adhesion of the coating, and reducing process defects caused by temperature fluctuations.

[0098] Furthermore, in step S14, the laser system and the second motion system are used to cover the surface of the teardrop-shaped freeform substrate 9 with the texture pattern corresponding to the pre-made texture pattern information to complete the exposure operation;

[0099] The laser system uses a dmd spatial light modulator and a beam shaping lens group to determine the pre-fabricated texture micro-units, and projects the pre-fabricated texture micro-units onto a small light curtain onto a teardrop-shaped freeform surface substrate 9.

[0100] In this embodiment, the description illustrates a high-precision laser direct-write lithography device and its working process. This device consists of multiple precision mechanical axes and an advanced optical system, enabling precise processing of complex curved surfaces. A detailed analysis follows:

[0101] 1) Five-axis linkage system: The equipment has A-axis and C-axis (dual-axis cradle turntable), as well as X-axis, Y-axis and Z-axis (three linear axes), which can realize complex spatial motion trajectories.

[0102] 2) Laser direct writing head: Fixed on the cross module of the X and Z axes, responsible for emitting laser.

[0103] 3) Vision system: A 20-megapixel camera 6 and a telecentric lens 7 are mounted on the Z-axis to capture and identify the accurate position and shape of the substrate.

[0104] 4) Spatial light modulator (DMD): Used to control the shape and direction of the laser beam to adapt to different processing requirements.

[0105] 5) Beam shaping lens group: Further adjust the laser beam to ensure that it is accurately projected onto the substrate.

[0106] 6) Pre-fabricated texture micro-units: The designed texture pattern is projected onto the substrate through a laser system.

[0107] 7) Exposure process: The laser system and motion system work together to completely transfer the pre-made texture pattern onto the entire teardrop-shaped freeform substrate 9.

[0108] Imagine engraving a detailed map onto a spherical piece of glass. This device acts like a sophisticated paintbrush, precisely drawing every detail on the sphere's surface. First, the device's "eyes" (vision system) carefully observe the spherical glass, determining its shape and position. Then, the device's "arm" (five-axis linkage system) moves precisely to the correct position based on this information. Simultaneously, the "paintbrush" (laser direct-write head) adjusts the laser beam through a series of lenses and mirrors (beam shaping lens group and DMD) to adapt to the curvature of the sphere, drawing every detail of the map onto the surface. The entire process is like performing precise painting in three-dimensional space, ultimately forming a complete map pattern on the glass sphere.

[0109] Preferably, during the manufacturing process, there is a close relationship between the "prefabricated texture micro-units" and the "prefabricated texture pattern," which together define the surface features of the final product. The relationship and function between them are as follows:

[0110] 1) Texture micro-units: This usually refers to the basic graphic elements or units that make up a texture pattern. Each micro-unit contains specific lines, shapes, or structures, and they are the basis for building more complex patterns.

[0111] 2) Texture pattern: This refers to a complete pattern composed of multiple texture micro-units arranged and combined according to certain rules. The texture pattern defines the final appearance and characteristics of the product surface.

[0112] 3) Relevance: Texture micro-units are the "building blocks" that construct texture patterns. Their size, shape, and arrangement determine the final effect of the texture pattern. Texture patterns are achieved by replicating and arranging these micro-units, involving different combinations such as repetition, rotation, and mirroring. The design and selection of micro-units affect the functionality of the texture pattern, such as electromagnetic shielding effect, optical performance, or mechanical properties.

[0113] 4) Manufacturing Process: The manufacturing process begins with designing and determining the geometry and dimensions of the texture micro-units. Then, based on the required application and performance requirements, these micro-units are arranged into a texture pattern. Finally, using techniques such as laser direct-write lithography, these pre-made texture patterns are transferred onto the product substrate.

[0114] For example, to create a complex pattern on a piece of glass, which is composed of many small dots, each dot is a texture micro-unit, and the entire pattern is a texture pattern formed by arranging and combining these dots according to certain rules.

[0115] In laser direct-write lithography systems, the DMD (Digital Micromirror Device) spatial light modulator and beam-shaping lens group are typically used to control and adjust the characteristics of the laser beam to achieve precise pattern transfer. Their role is directly related to determining the pre-fabricated texture micro-units, but their main functions are to achieve the following:

[0116] 1) Beam Modulation: The DMD spatial light modulator modulates the incident laser beam by controlling an array of micromirrors. Specific micromirrors can be turned on or off, thereby controlling the beam path. This can be used to selectively form or block the beam to create desired micro-unit patterns.

[0117] 2) Pattern generation: DMD can quickly switch the state of micromirrors, thereby generating complex patterns along the path of the beam. These patterns can be texture patterns composed of multiple micro-units.

[0118] 3) Beam Shaping: The beam shaping lens group is used to adjust the shape and size of the laser beam, ensuring that the beam is projected onto the substrate in the desired shape and size. This helps to accurately transfer micro-cell patterns onto the substrate.

[0119] 4) Precise alignment: In complex manufacturing processes, these devices can also help to precisely align patterns, ensuring that they are placed accurately in specific locations on the substrate as designed.

[0120] 5) Dynamic adjustment: The DMD and beam shaping lens group can be dynamically adjusted to adapt to different pattern designs and manufacturing requirements, providing a high degree of flexibility.

[0121] Therefore, it can be said that the DMD spatial light modulator and beam shaping lens group are used to achieve the precise transfer and positioning of pre-fabricated textured micro-units. They are key components to ensure the pattern accuracy and quality during laser direct writing lithography. Through these devices, the designed textured micro-units can be accurately projected and transferred onto the substrate according to the pre-fabricated texture pattern to achieve the desired surface features.

[0122] In summary, the technology used in step S14 achieves high-resolution and high-precision texture pattern exposure by precisely controlling the coordinated operation of the laser system and the second motion system, combined with the DMD spatial light modulator and beam shaping lens group. This ensures that the pre-made texture micro-units can be uniformly and accurately projected and covered on the entire surface of the teardrop-shaped freeform substrate 9, thereby giving it a predetermined functional texture pattern while maintaining the original characteristics of the surface.

[0123] Furthermore, the wavelength of the laser source in the laser system is 375±10nm.

[0124] In summary, by selecting a laser light source with a wavelength of 375±10nm, this technology achieves precise absorption and processing of specific materials while minimizing the heat-affected zone, effectively avoiding unnecessary damage to the teardrop-shaped freeform substrate 9, and ensuring the precision of micro-nano structure processing and the integrity of the substrate material.

[0125] Furthermore, in step S15, the stripping solution is sprayed onto the surface of the droplet-shaped freeform substrate 9 for development. The thickness of the micron-sized thin film coating formed after the solvent in the photoresist evaporates will vary at different times during the development process. The development time is defined by determining the different photoresist materials and the thickness difference of the micron-sized thin film coating.

[0126] In step 17, the stripping solution is sprayed onto the surface of the teardrop-shaped freeform substrate 9 for stripping. The thickness of the micron-sized thin film coating formed after the solvent in the photoresist evaporates will vary at different times during the stripping process. The stripping operation time is defined by determining the different photoresist materials and the thickness difference of the micron-sized thin film coating.

[0127] In summary, by precisely controlling the spraying of the stripping solution during the development and stripping processes, combined with real-time monitoring of different photoresist materials and the thickness of micron-sized thin film coatings, this technology enables precise definition of the development and stripping operation times, ensuring uniform removal of the photoresist coating and accurate transfer of micron-sized patterns, thereby optimizing the accuracy and repeatability of the entire photolithography process.

[0128] Furthermore, step S16 includes the following steps:

[0129] The developed teardrop-shaped freeform surface substrate 9 is clamped in a self-rotating tooling fixture;

[0130] The surface of the water droplet-shaped freeform substrate 9, which is clamped in a self-rotating tooling fixture, is bombarded and cleaned using an RF ion source according to a preset operation time.

[0131] A chromium film, a copper film, another chromium film, another copper film, and a final chromium film are sequentially deposited on the surface of the teardrop-shaped freeform substrate 9.

[0132] In summary, the technology used in step S16 achieves uniform and high-quality electromagnetic shielding layer deposition by fixing the developed teardrop-shaped freeform surface substrate 9 in a rotating fixture, using an RF ion source for surface bombardment cleaning, and then precisely evaporating multiple alternating chromium and copper films. This ensures precise alignment and cleanliness of the substrate, thereby improving the performance and reliability of the final product.

[0133] In summary, this fabrication method is used to create teardrop-shaped freeform optical masks with electromagnetic shielding and extremely low diffraction characteristics. Through these techniques, the manufacturing process can: reduce laser damage to the back surface of the substrate due to the use of precise laser control and beam shaping techniques; reduce misalignment problems caused by multiple scanning etching through precise operation of a vision system and robotic arms; reduce damage to the substrate caused by high-energy laser etching through baking, developing, and spin-drying steps; and improve the quality and uniformity of the electromagnetic shielding layer and reduce its impact on the substrate through vacuum evaporation coating and ion source cleaning.

[0134] Example 2:

[0135] A method for creating random metallic textures on freeform surfaces, the method comprising:

[0136] S21, Ultrasonic cleaning of teardrop-shaped freeform surface substrate 9.

[0137] S22. Vacuum evaporation coating is performed on the water droplet-shaped freeform surface substrate 9 after ultrasonic cleaning.

[0138] S23. Photoresist is coated onto the teardrop-shaped freeform substrate 9 after coating.

[0139] S24. Bake the teardrop-shaped freeform substrate 9 after the photoresist film is coated to solidify the photoresist;

[0140] S25. Determine the pre-made texture pattern information. Based on the pre-made texture pattern information, obtain the visual image information of the teardrop-shaped freeform surface substrate 9 after baking and solidifying the adhesive. Analyze the visual image information and the pre-made texture pattern information to determine the laser motion trajectory. The laser motion trajectory is used to control the laser to perform exposure operation on the teardrop-shaped freeform surface substrate 9 after baking and solidifying the adhesive according to the pre-made texture pattern information.

[0141] S26. Etch the developed teardrop-shaped freeform surface substrate 9;

[0142] S27. Remove the adhesive from the etched teardrop-shaped freeform surface substrate 9.

[0143] S28, Water droplet-shaped freeform substrate 9 after ultrasonic cleaning and adhesive removal;

[0144] S29. Transfer the cleaned and degummed teardrop-shaped freeform substrate 9 to a projection optical imager for texture measurement.

[0145] In this embodiment, the teardrop-shaped freeform substrate 9 is ultrasonically cleaned in step S21.

[0146] In step S22, the cleaned product is clamped onto a specific tooling fixture with an on-board rotation to fabricate the electromagnetic shielding metal layer. A vacuum evaporation deposition method is used, with surface bombardment cleaning using an RF ion source for 10 minutes. Then, 15nm chromium, 100nm copper, 15nm chromium, 100nm copper, and 15nm chromium films are deposited sequentially. The process parameters are: vacuum chamber vacuum degree 3.0×10³ Pa, vacuum chamber temperature 200°C, on-board rotation 20 r / min, vacuum holding time 30 min, followed by room temperature stress release and a 1-hour resting time.

[0147] In step S23, a vision-guided robotic arm, equipped with an ultrasonic spray gun, applies photoresist to a teardrop-shaped freeform surface workpiece with an electromagnetically shielded metal layer. The vision system uses a 2000W camera 6 and a telecentric lens 7. The teardrop-shaped freeform substrate 9 is fixed on a contour-following base, which is covered with a high-precision, temperature-uniform, and controllable heating flexible cloth. Before the coating process, the temperature control heating function is activated, and the coating process is initiated only after the temperature display stabilizes. This base significantly reduces the problem of inconsistent photoresist thickness across different areas of the teardrop-shaped freeform substrate 9 due to gravity and the low viscosity of the photoresist. After acquiring the accurate coordinates of the teardrop-shaped freeform substrate 9 through vision, the robotic arm moves according to a pre-programmed 3D trajectory to perform the coating operation. The operating parameters are as follows: robotic arm movement speed 10mm / s, contour base temperature 30℃, spray gun distance from the normal of the teardrop-shaped freeform surface 45mm, photoresist viscosity 1~2cps, ultrasonic frequency 5000kHz, liquid supply flow rate 1.8L / h, using a micro airflow of ≤0.15MPA to guide the flow, so that the photoresist falls evenly onto the substrate to be sprayed, and the solvent evaporates to form a micron-sized thin film coating.

[0148] In step S24, the teardrop-shaped freeform substrate 9 after photoresist film formation is transferred to a clean constant temperature oven for baking and solidification.

[0149] In step S25, the laser direct-write lithography equipment employs a dual-axis cradle turntable (A-axis and C-axis) combined with a three-linear-axis (X-axis, Y-axis, and Z-axis) configuration. The laser direct-write head is fixed on the X-axis and Z-axis cross-shaped modules, while the dual-axis cradle turntable (A-axis and C-axis) is fixed on the Y-axis. Simultaneously, a 2000W pixel camera 6 with a telecentric lens 7 is fixed on the Z-axis for vision. After obtaining the accurate coordinate system of the teardrop-shaped freeform substrate 9 through vision, the five axes can move according to a pre-programmed spatial outward-expanding surface trajectory. The laser source uses a wavelength of 375±10nm. The laser system projects pre-fabricated texture micro-units onto the teardrop-shaped freeform substrate 9 through a DMD spatial light modulator and a special beam-shaping lens group. Through the coordinated operation of the laser system and the motion system, the pre-fabricated texture pattern is spread across the entire surface of the teardrop-shaped freeform metal layer, thus completing the exposure.

[0150] In step S26, the exposed product is fixedly placed on a developing device with a contoured vacuum adsorption rotating shaft. The rotating shaft speed is adjusted to 30-40 rpm, and the developing solution is simultaneously sprayed onto the surface of the droplet-shaped freeform metal layer for development. The development time will vary depending on the photoresist material and the thickness of the micron-sized film; the development time can be customized on the device. After development, the spray automatically shuts off, and the rotating shaft speed jumps to 200-300 rpm for spin-drying. The entire process is controlled by a microcomputer program; different production formulas can be added for different products.

[0151] In step S27, the developed product is fixedly placed on an etching device with a contour-following vacuum adsorption rotating shaft. The rotating shaft speed is adjusted to 30-40 rpm, and a specially formulated etching solution is simultaneously sprayed onto the surface of the teardrop-shaped freeform substrate 9 for etching. The specially formulated etching solution can simultaneously etch both chromium and copper. After etching is complete, the spray automatically shuts off, and the rotating shaft speed jumps to 200-300 rpm for spin-drying. The entire process is controlled by a microcomputer program; different production formulas can be added for different products.

[0152] In step S28, the etched electromagnetic shielding teardrop-shaped freeform surface is placed on a degumming device with a contour-following vacuum adsorption rotating shaft. The rotating shaft is turned on and its speed adjusted to 30-40 rpm, simultaneously spraying degumming liquid onto the teardrop-shaped freeform surface for degumming. The degumming time is approximately 2-4 minutes. After degumming is complete, the spray automatically shuts off, and the rotating shaft speed jumps to 200-300 rpm for spin-drying. The entire process is controlled by a microcomputer program; different production formulas can be added for different products.

[0153] In step S29, the degummed product is placed in an ultrasonic cleaning tank to clean off any remaining degumming liquid. At this point, the teardrop-shaped freeform optical cover with electromagnetic shielding function and extremely low diffraction is completed.

[0154] In step S210, the texture is measured under a projection optical imager. The line width of the texture is 5 μm, and the overall appearance of the texture is free from defects such as deformation, broken lines, and missing corners.

[0155] In summary, the technical advantage of the freeform surface random metal texture fabrication method lies in the fact that, through a series of precisely controlled steps such as ultrasonic cleaning, vacuum evaporation coating, photoresist coating and baking, precise laser exposure, development etching, photoresist removal, and ultrasonic cleaning, a uniform, precise, and predetermined electromagnetic shielding random metal texture is fabricated on a teardrop-shaped freeform surface substrate 9. At the same time, the integrity and optical performance of the substrate are ensured. Finally, the texture is measured by an optical imager to verify the product quality.

[0156] Preferably, the difference between the two embodiments lies in that the second method, because it involves pre-coating, places higher demands on the uniformity and integrity of the coated layer during photoresist curing and exposure to avoid affecting the accuracy of the final pattern. If the coating material has specific requirements regarding photoresist adhesion or the baking process, this will influence the choice of manufacturing process. The first method is suitable for situations where the substrate needs to undergo certain surface treatments or where a specific pattern needs to be formed before coating. The second method is suitable for situations where a pattern needs to be formed on a specific material before subsequent processing.

[0157] Furthermore, step S26 includes:

[0158] The etching solution is sprayed onto the developed droplet-shaped freeform substrate 9, the etching solution being used to simultaneously etch chromium and copper;

[0159] The etched teardrop-shaped freeform surface substrate 9 is then dried.

[0160] In summary, the technical effect of step S26 is that by simultaneously removing the chromium and copper layers on the developed teardrop-shaped freeform substrate 9 through spray etching solution, precise metal layer pattern transfer is achieved. The subsequent drying process ensures the cleanliness of the substrate and the smooth progress of subsequent processes, thereby giving the substrate the required functional texture while maintaining the surface characteristics.

[0161] In summary, this fabrication method is used to create teardrop-shaped freeform optical masks with electromagnetic shielding and extremely low diffraction characteristics. Through these techniques, the manufacturing process can: reduce laser damage to the back surface of the substrate due to the use of precise laser control and beam shaping techniques; reduce misalignment problems caused by multiple scanning etching through precise operation of a vision system and robotic arms; reduce damage to the substrate caused by high-energy laser etching through baking, developing, etching, and resist removal steps; and improve the quality and uniformity of the electromagnetic shielding layer and reduce its impact on the substrate through vacuum evaporation coating and ion source cleaning.

[0162] Preferably, in both embodiments, the "teardrop-shaped" feature refers to the shape of the substrate; it is a specific technical feature but not necessarily necessary for manufacturing a freeform optical cover with electromagnetic shielding and extremely low diffraction. The teardrop-shaped design is based on the following considerations:

[0163] Optical performance: The teardrop shape contributes to specific optical properties, such as reducing light reflection or scattering and improving optical imaging quality.

[0164] Electromagnetic shielding effect: Specific shapes help optimize the electromagnetic shielding effect, and the performance of the shielding layer can be enhanced or adjusted through shape design.

[0165] Structural strength: The teardrop shape provides better structural strength, making it more suitable for withstanding mechanical stress or environmental factors.

[0166] Aesthetic or design requirements: In some applications, the teardrop shape is a design choice to meet specific aesthetic or brand identity needs.

[0167] Adaptability of manufacturing processes: Teardrop-shaped curved surfaces require specific manufacturing processes to achieve, such as photoresist coating and laser direct writing lithography mentioned in the article. These processes are particularly suitable for handling curved surface shapes.

[0168] However, whether a "teardrop shape" is a necessary technical feature depends on the specific application and performance requirements of the final product. In some cases, other substrate shapes also meet the technical requirements, as long as they can achieve the required functionality and performance. Therefore, a "teardrop shape" can be considered a design choice rather than an absolutely necessary technical feature.

[0169] For reference, the existing technology manufacturing process is as follows:

[0170] Step 1: Cleaning the curved surface substrate;

[0171] Step 2: Apply a titanium and copper film using vacuum coating technology;

[0172] Step 3: Remove the material using multiple laser processing steps with a 515nm femtosecond laser;

[0173] Step 4: Ultrasonic cleaning;

[0174] Step 5: Visual inspection using an imaging device;

[0175] The shortcomings and deficiencies of existing inventions:

[0176] Curved electromagnetic shielding substrates are all laser-transparent. While removing the curved metal coating, the laser will be transmitted to the other side of the curved surface, and the transmitted laser will destroy the grid on the other side.

[0177] For curved surfaces, at least two scanning etching operations are required, which places extremely stringent demands on the repeatability accuracy of laser direct writing equipment. Multiple scanning etching operations have a high probability of resulting in misalignment.

[0178] High-energy laser etching can cause irreparable surface damage and changes in internal stress of curved substrates, affecting the imaging quality of the curved surface and the strength of the substrate.

[0179] This application enables the fabrication of uniform photoresist films on teardrop-shaped freeform surfaces. This technology allows for the fabrication of irregular meshes on complex teardrop-shaped freeform surfaces. The designed texture pattern can be formed in a single exposure. There is no displacement deviation caused by repeated repositioning. The fabrication process does not damage the teardrop-shaped freeform surface substrate, ensuring the original strength and optical properties of the substrate. It avoids texture damage in the straight lines of the teardrop-shaped freeform surface caused by laser transmission, allowing for the fabrication of complete irregular meshes. The use of a laser projection small light curtain technology is many times more efficient than existing technologies.

[0180] More importantly, it avoids laser transmission damage: the new process prevents laser damage to the other side of the freeform surface during fabrication. Texture pattern formation in a single exposure: compared to existing technologies, the new method completes the designed texture pattern in a single exposure, eliminating displacement deviations caused by repeated overlays. No damage to the substrate: the teardrop-shaped freeform surface substrate is not damaged during fabrication, maintaining the original strength and optical properties of the substrate. Complete irregular mesh fabrication: the new technology can produce complete irregular meshes without damage from laser transmission. Improved production efficiency: using laser projection small light curtain technology, production efficiency is significantly improved compared to existing technologies. Combination of optical performance and electromagnetic shielding: the freeform random metal mesh maintains electromagnetic shielding performance while also achieving excellent optical performance, without optical diffraction issues.

[0181] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for creating random metallic textures on freeform surfaces, characterized in that, The method for creating random metallic textures on freeform surfaces includes: S11, Ultrasonic cleaning of teardrop-shaped freeform surface substrates. S12. Photoresist is coated onto a teardrop-shaped freeform substrate after ultrasonic cleaning. S13. Bake the photoresist-coated teardrop-shaped freeform substrate to solidify the photoresist. S14. Determine the pre-made texture pattern information. Based on the pre-made texture pattern information, obtain the visual image information of the water droplet-shaped freeform surface substrate after baking and solidifying the adhesive. Analyze the visual image information and the pre-made texture pattern information to determine the laser motion trajectory. The laser motion trajectory is used to control the laser to perform exposure operation on the water droplet-shaped freeform surface substrate after baking and solidifying the adhesive according to the pre-made texture pattern information. S15. Develop the exposed teardrop-shaped freeform substrate; S16. Vacuum evaporation coating is performed on the developed teardrop-shaped freeform surface substrate; S17. Remove the adhesive from the coated teardrop-shaped freeform surface substrate; S18. Water droplet-shaped freeform substrate after ultrasonic cleaning and degumming. S19. Transfer the cleaned and degummed teardrop-shaped freeform substrate to a projection optical imager for texture measurement. In step S12, a photoresist film is formed and coated on the water droplet-shaped freeform surface substrate after ultrasonic cleaning by an ultrasonic coating mechanism. The ultrasonic coating mechanism includes a control box (1), a first motion system (2), a contour heating base (3), and a support frame (4) located on the control box (1). The first motion system (2) is equipped with an ultrasonic nozzle (5), and the support frame (4) is equipped with a vision system. Step 12 also includes the following steps: Based on a vision system, obtain the motion coordinate system of a teardrop-shaped freeform surface substrate; Determine the preset three-dimensional trajectory; According to the preset three-dimensional trajectory and the motion coordinate system, the first motion system (2) is controlled to perform a coating operation on the teardrop-shaped freeform surface substrate located in the contour heating base (3); The contour heating base (3) is provided with a controllable heating flexible cloth. Before performing step S12, the following steps are also included: Determine whether the temperature parameters of the controllable heating flexible fabric have reached a preset threshold; If so, a first window will be pushed to prompt the ultrasonic coating mechanism to start photoresist film coating; If not, a second window will be pushed to indicate that the conditions for starting the ultrasonic coating mechanism to form a photoresist film are not met, and an audible and visual alarm will be triggered.

2. The method for creating random metallic textures on freeform surfaces according to claim 1, characterized in that, The preset threshold is 30±2℃.

3. The method for creating random metallic textures on freeform surfaces according to claim 1, characterized in that, In step S14, the laser system and the second motion system are used to spread the texture pattern corresponding to the pre-made texture pattern information all over the surface of the teardrop-shaped freeform substrate to complete the exposure operation; The laser system uses a dmd spatial light modulator and a beam shaping lens group to determine pre-fabricated texture micro-units, and projects the pre-fabricated texture micro-units onto a small light curtain onto a teardrop-shaped freeform surface substrate.

4. The method for creating random metallic textures on free-form surfaces according to claim 3, characterized in that, The wavelength of the laser source in the laser system is 375±10nm.

5. The method for creating random metallic textures on freeform surfaces according to claim 1, characterized in that, In step S15, the stripping solution is sprayed onto the surface of the droplet-shaped freeform substrate for development. The thickness of the micron-sized thin film coating formed after the solvent in the photoresist evaporates will vary at different times during the development process. The development time is defined by determining the different photoresist materials and the thickness difference of the micron-sized thin film coating. In step 17, the stripping solution is sprayed onto the surface of the teardrop-shaped freeform substrate to remove the photoresist. The thickness of the micron-sized thin film coating formed after the solvent in the photoresist evaporates will vary at different times during the stripping process. The stripping operation time is defined by determining the different photoresist materials and the thickness difference of the micron-sized thin film coating.

6. The method for creating random metallic textures on freeform surfaces according to claim 1, characterized in that, Step S16 includes the following steps: The developed teardrop-shaped freeform surface substrate is clamped in a rotating tooling fixture; An RF ion source was used to perform surface bombardment cleaning on a teardrop-shaped freeform substrate clamped in a self-rotating fixture according to a preset operation time. A chromium film, a copper film, another chromium film, another copper film, and a final chromium film are sequentially deposited on the surface of a teardrop-shaped freeform substrate.

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