A method for laser processing transparent materials based on coating

Abstract

The present invention relates to the field of laser processing technology, and discloses a method for laser processing transparent materials based on coatings, comprising the following steps: step 1, fixing the transparent material to be processed; step 2, processing the coating on the surface of the transparent material; step 3, adjusting the focus of the light beam of the laser processing equipment, and making the focus located on the surface to be processed of the transparent material; step 4, processing the transparent material using the laser processing equipment; step 5, after the processing is completed, removing the remaining coating on the transparent material. The processing method proposed by the present invention adopts the method of coating the surface with an organic coating, which can reduce the scattering of the laser during laser processing and guide the light beam to focus on the surface of the material, which can not only solve the problem of laser defocusing, so that the laser beam can be effectively focused and process the upper surface of the transparent material, but also enhance the light absorption rate of the material and improve the processing efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of laser processing, and in particular to a coating-based laser processing method for transparent materials. Background Art

[0002] As an advanced processing method, laser processing technology has demonstrated its unique advantages in many fields. It is widely used in optical components, medical devices, microfluidic channels and electronic product manufacturing. Laser processing technology can achieve microfluidic channel processing at the micron or even nanometer level due to its extremely high processing accuracy. Laser processing has high efficiency and good flexibility, and is also widely used to process the structure of transparent light guide plates to enhance the luminous effect of electronic products.

[0003] In the application of processing transparent materials, commonly used methods are photolithography and injection molding, but these methods have obvious disadvantages. Photolithography usually requires specific photosensitive materials to transfer patterns, which limits the types of materials that can be used and the application fields, and its flexibility is low; injection molding methods may not be able to produce very small feature sizes due to the limitations of material fluidity. In addition, injection molding is usually limited to injection moldable plastic materials, such as PMMA, PC, etc.

[0004] With the rapid development of laser technology, laser processing of transparent materials has gradually entered the public's field of vision. Through laser processing technology, tiny concave and convex structures can be directly printed on the surface of transparent materials, thereby changing the direction and shape of light propagation and achieving precise control and distribution of light beams. Therefore, laser processing technology is suitable for light guide plate processing of electronic products. Compared with traditional light guide plate processing methods, laser processing of light guide plates has the advantages of greater processing flexibility, high precision, high efficiency and a wide range of processable materials.

[0005] In the application of nanosecond laser processing, there are many studies on laser cutting of non-transparent materials. At present, there are still the following problems to be solved:

[0006] First, in situations where high focusing accuracy is required for processing microstructures and micropits, femtosecond lasers are often used for microstructure processing of transparent materials. This is because the pulse width is larger than that of nanosecond lasers, and the laser is affected by refraction and reflection during its propagation inside the material. Changes in the refractive index will cause the laser beam to deflect to varying degrees. In transparent materials, the scattering of lasers is more obvious, and nanosecond lasers have obvious defocusing, so they cannot be accurately focused on the surface of transparent materials.

[0007] Secondly, glass is a material commonly used in processing light guide plates. It has the advantages of low absorption rate, high optical clarity, and low price, but it is also a material that easily scatters light. Therefore, due to the low light absorption of glass, defocusing is prone to occur during laser processing, that is, light will be backscattered when entering the surface of the material, which makes it difficult for the laser beam to accurately focus on the surface of the material. This phenomenon will reduce the efficiency and accuracy of laser processing, thereby affecting the processing quality or causing material damage.

[0008] At present, the methods to solve the laser defocusing problem and achieve laser focusing mainly include: using focusing lenses with special shapes and materials, using high-precision laser processing equipment such as femtosecond lasers to improve focusing accuracy, or changing the refractive index distribution of the material through the photothermal effect, heating the material surface to reduce the defocusing effect, and thus achieve laser focusing.

[0009] However, due to the high price of femtosecond lasers, the complexity of their construction, and the difficulty in obtaining and maintaining them, short-pulse laser processing is currently mostly used in China; the use of special focusing lenses not only increases costs but may also affect the original processing effect; the method of heating the surface of the material to change its refractive index distribution is prone to thermal damage and material deformation. In order to avoid these problems, the temperature of the heating stage must be strictly controlled during the processing, which often leads to a significant extension of the processing cycle.

[0010] Based on this, the present invention proposes a coating-based method to achieve nanosecond laser processing of transparent materials.

[0011] And during the research, the applicant found that traditional light-absorbing coatings usually use inorganic or metal oxide materials with high absorption rates such as carbon black, titanium dioxide, zinc oxide, etc., and reduce light scattering by reasonably selecting the thickness and structure of the coating. However, due to their relatively stable properties, these materials often require acid and alkali corrosion or sandpaper polishing to remove them. For relatively fragile transparent material surfaces or when the structure being processed is relatively fine, acid and alkali corrosion and sandpaper polishing will destroy the original processing structure, thereby affecting the processing quality and efficiency. Summary of the invention

[0012] In order to solve the technical problems raised in the background technology, the present invention provides a coating-based laser processing method for transparent materials.

[0013] The present invention is implemented by the following technical solution: A method for laser processing transparent materials based on coating, comprising the following steps:

[0014] Step 1, fixing the transparent material to be processed;

[0015] Step 2, processing a coating on the surface of the transparent material;

[0016] Step 3, adjusting the beam focus of the laser processing equipment so that the focus is located on the surface to be processed of the transparent material;

[0017] Step 4: Processing the transparent material using laser processing equipment;

[0018] Step 5: After processing, remove the remaining coating on the transparent material.

[0019] Optionally, the method for processing the coating in step 2 is as follows: the coating preparation method is as follows: a black organic pigment and an organic solvent are mixed and stirred fully, and then impurities are removed by screening to obtain a coating solution, and then the coating solution is sprayed on the surface to be processed of the transparent material to form a coating with uniform thickness. The coating with uniform thickness can make the energy distribution uniform during laser processing to ensure the processing effect.

[0020] Optionally, before processing the coating, the surface of the transparent material needs to be cleaned with an ethanol solution and then wiped with dust-free paper to ensure that the surface of the transparent material is dry, flat, dust-free and oil-free.

[0021] Optionally, after the coating is sprayed, it is necessary to determine whether the coating thickness is uniform, and the processed coating thickness is 50μm-200μm to ensure that it can effectively absorb laser energy, while avoiding the obstruction of laser energy penetration due to excessively thick coating and the inability to effectively absorb energy due to excessively thin coating.

[0022] Specifically, the laser processing equipment contains:

[0023] Coarse focus module; used for roughly adjusting the focal position of laser processing and making the focus located on the upper surface of the coating; the coarse focus module includes a micron-level lifting stepper motor for roughly adjusting the focal position of laser processing.

[0024] Fine focus module: used to finely adjust the focal position of laser processing and make the focal point located on the upper surface of the transparent material. The fine focus module includes a Z-axis motion table for finely adjusting the focal position of laser processing.

[0025] Specifically, the method for removing the coating on the surface of the transparent material is as follows: soak the transparent material in an organic solvent for a period of time, then take it out and rinse it with clean water.

[0026] Optionally, the material of the transparent material includes but is not limited to glass, polycarbonate, and methyl methacrylate.

[0027] Optionally, when the surface area of ​​the transparent material to be coated is greater than 1m 2 , immersing the transparent material in the coating solution, then taking it out and drying it, and finally forming a coating on the surface of the transparent material. The above-mentioned immersion method can improve the efficiency of preparing the coating.

[0028] Optionally, the raw materials of the coating may also be food-grade organic dyes such as plant carbon black and anthocyanin instead of black organic pigment.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The processing method proposed in the present invention adopts the method of coating the surface with an organic coating, which can reduce the scattering of the laser during laser processing and guide the light beam to focus on the surface of the material. It can not only solve the problem of laser defocusing, so that the laser beam can be effectively focused and process the upper surface of the transparent material, but also enhance the light absorption rate of the material and improve the processing efficiency.

[0031] The organic coating provided by the present invention is soluble in an organic solvent, and can be removed without damage after processing, without any adverse effect on the material itself and the processing effect.

[0032] The processing method proposed in the present invention can not only be applied to materials such as PDMS, but other transparent materials can also be processed using the method proposed in the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a comparative diagram of laser processing of non-transparent materials and transparent materials; among which: Figure 1 Part (a) of Figure 1 Part (c) is a schematic diagram of laser focusing on the upper surface of a non-transparent material and processing the upper surface thereof; Figure 1 Part (b) of Figure 1 Part (d) is a schematic diagram showing that the laser is focused on the upper surface of a transparent material for processing and causes damage to the lower surface;

[0034] Figure 2 The top surface morphology of the transparent material before and after the coating is cleaned after being coated with an organic coating and processed;

[0035] Figure 3 The schematic diagram of the method for laser processing transparent materials based on coating proposed by the present invention and the morphology of the processed product; wherein: Figure 3 Part (a) is a schematic diagram of applying an organic coating and performing laser processing; Figure 3 Part (b) shows the top and bottom surface morphologies of the product after being coated with an organic coating and laser processed.

[0036] Figure 4 A schematic diagram of mixing and spraying organic dyes onto the surface of a transparent material;

[0037] Figure 5 Schematic diagram of the principle of laser processing after coating;

[0038] Figure 6Schematic diagram of the principle of soaking off the organic coating after laser processing;

[0039] Figure 7 Side view of processed glass before and after coating;

[0040] Figure 8 Flow chart of the coating-based laser processing method for transparent materials proposed in the present invention. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0042] Embodiment 1:

[0043] Reference Figure 1-Figure 8 , This scheme proposes a coating-based laser processing method for transparent materials, and its specific operation steps are as follows:

[0044] Prepare a coating solution; select a suitable black organic pigment and an organic solvent, mix the two, stir them thoroughly, and screen to remove impurities to prepare a uniformly diluted coating solution. Specifically, aniline black can be used as a dye and ethanol can be used as a solvent. The mixing ratio of the two only needs to be such that the ethanol can just dissolve the dye, and there is no special requirement.

[0045] Spray coating: Use ethanol solution to clean the surface of the transparent material and then wipe it with dust-free paper to ensure that it is dry, flat, dust-free and oil-free so that the subsequent coating on the surface of the material can be evenly covered. Spray the mixed solution evenly on the surface of the transparent material. And decide whether to spray multiple times based on the spraying effect.

[0046] Adjust the focus; according to the clarity of the light spot on the black coating surface, adjust the nanosecond laser micron-level lifting stepper motor to make it focus on the black coating surface for coarse focusing. In the preliminary experiment, adjust the brightness of the laser itself according to the precise Z-axis moving stage for fine focusing.

[0047] In the specific operation of this solution, the laser defocusing phenomenon on the surface of transparent materials can be greatly reduced because the coating thickness is extremely small and the laser is blocked by the black coating. At the same time, the black coating can enhance the absorbance of the material, making it easier for the laser to process the material and produce better processing effects. The surface of the material removed by the laser will take away the black coating, so even if the coating is applied to the surface of the transparent material, only the upper surface of the transparent material is processed.

[0048] In this scheme, since the black coating is made by mixing organic pigments and organic solvents, and the transparent material is insoluble in organic solvents, the processed sample can be immediately placed in a container after processing, and a sufficient amount of organic solvent is added. The liquid level should completely cover all areas of the sheet. After a long period of immersion, take out the processed sample and rinse it with clean water. Subsequently, it is decided whether to use ultrasonic cleaning equipment such as an ultrasonic cleaner in an organic solution to further remove residual impurities based on the removal effect. Figure 4 , and finally achieve damage-free removal of the black coating, thus causing no adverse effects on the material and processing results.

[0049] like Figure 3 As shown, in order to solve the problem of difficulty in focusing on the surface of transparent materials during laser processing, an organic coating is applied to the surface to reduce the scattering of the laser and guide the light beam to focus on the material surface. This not only solves the problem of laser defocusing, but also enhances the light absorbency of the material and improves processing efficiency. In addition, the organic coating is soluble in organic solvents and can be removed without damage, without any adverse effects on the material itself and the processing effect.

[0050] The processing method provided in this scheme uses the following equipment to work, and the equipment list is as follows:

[0051] (1) A laser, as a processing light source, which can emit light that can process fluorescent polymer materials.

[0052] (2) Pre-optical path: adjust laser energy, phase and other related parameters.

[0053] (3) Micrometer-level lifting stepper motor to roughly adjust the focal position of laser processing.

[0054] (4) Z-axis motion table, to further fine-tune the focal position of laser processing.

[0055] (5) Glass materials, as transparent materials to be processed.

[0056] The specific processing process is as follows:

[0057] (1) Open the optical path and adjust the laser processing parameters such as power. Import the processing file of the calibration sample into the control software.

[0058] (2) Mix black organic pigment and organic solvent, such as Figure 4 As shown, after being fully stirred to remove impurities, the mixed liquid is sprayed onto the glass sheet to ensure uniform coating. The coated glass sheet is then placed on a stage and fixed for subsequent laser focusing and processing.

[0059] (3) Move the micron-level lifting stepper motor upward, and then slowly move the micron-level motor downward, gradually bringing the laser focus closer to the treated glass, and observe the clarity of the preview laser frame on the coating surface until it reaches the clearest position. At this time, use the micron-level lifting stepper motor to roughly adjust the focus position and end.

[0060] (4) The processing speed and parameters are adjusted down for preliminary experiments. With the help of the micron-level Z-axis motion stage, the laser is continuously focused according to the brightness of the laser during the processing. The laser is then processed at the brightest spot on the upper surface. At this point, the entire focus adjustment process is completed to ensure that the laser focus can be processed onto the upper surface of the material without scattering. Figure 5 As shown, laser processing is performed on glass material.

[0061] (5) In order to enhance the recognition effect of the processing position and determine whether the structure of the laser processed glass sheet is on the upper surface or the lower surface before and after the processing, this experiment processed a 5-row 5-column point array on the glass sheet before and after the processing for observation and comparison of the experimental results.

[0062] (6) If Figure 6 As shown, the coated glass slice is immersed in an organic solvent such as methanol, ethanol, etc. until the organic black coating is dissolved, thereby removing the black coating without damage and obtaining a complete structure.

[0063] The method proposed by the present invention has the following processing effects:

[0064] After spin coating, the scattering of laser can be reduced and the laser beam can be guided to focus on the surface of the material. During the laser processing step, nanosecond laser processing can be used on the upper surface of the glass material, such as Figure 2 As shown, the organic coating can be removed without damage, and there is no adverse effect on the material itself and the processing effect. After the processed workpiece is soaked and cleaned with an organic solvent, the organic coating is soluble in the organic solvent. Figure 3 As shown in part (b) of FIG. 1 , the material has a processed structure on the upper surface and no structure on the lower surface. Figure 7 Cross-sectional view of the processed material. There are pits on the upper surface, which enables the laser with a large pulse width to focus on the surface of the glass material.

[0065] Worth mentioning:

[0066] 1. In addition to glass materials, polycarbonate (PC) and methyl methacrylate (PMMA) can also be used to make light guide plates. They can be used to replace glass for experiments to simulate the laser defocusing phenomenon that occurs when transparent light guide plate materials are processed by laser, making the laser processing position of transparent materials uncontrollable.

[0067] 2. In addition to the organic black pigment and the organic black solvent mixed coating, organic dyes such as food-grade black dyes can also be used to color the coating on the sheet of the present invention, and common food coloring and carbon black extracted from burnt plant materials can be used as dyes.

[0068] 3. The method of using organic black coating to reduce laser defocusing proposed in the present invention, in addition, for larger workpieces, specifically, when the surface area of ​​the transparent material to be coated is greater than 1m 2 , immersing the transparent material in the coating solution, then taking it out and drying it, and finally forming a coating on the surface of the transparent material. The above-mentioned immersion method can improve the efficiency of preparing the coating.

[0069] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for laser processing of transparent materials based on coating, characterized in that: The steps include: Step 1, fixing the transparent material to be processed; Step 2, processing a coating on the surface of the transparent material; Step 3, adjusting the beam focus of the laser processing equipment and making the focus located on the surface to be processed of the transparent material; Step 4: Processing the transparent material using laser processing equipment; Step 5: After processing, remove the remaining coating on the transparent material; The method for processing the coating in step 2 is as follows: a black organic pigment and an organic solvent are mixed and stirred fully, and then impurities are removed by screening to obtain a coating solution, and then the coating solution is sprayed on the surface to be processed of the transparent material to form a coating with uniform thickness; the thickness of the processed coating is 50 μm-200 μm; Before processing the coating, the surface of the transparent material needs to be cleaned with an ethanol solution and then wiped with dust-free paper to ensure that the surface of the transparent material is dry, flat, dust-free and oil-free; The transparent material includes glass, polycarbonate or polymethyl methacrylate.

2. The method for laser processing transparent materials based on coating as claimed in claim 1, characterized in that: The raw material of the coating can also be plant carbon black or anthocyanin instead of black organic pigment.

3. The method for coating-based laser processing of transparent materials according to claim 1, characterized in that: After the coating is sprayed, it is necessary to determine whether the coating thickness is uniform.

4. The method for coating-based laser processing of transparent materials according to claim 1, characterized in that: The laser processing equipment contains: Coarse focus module; Used to roughly adjust the focal position of laser processing and make the focus on the upper surface of the coating; Fine focus module; It is used to finely adjust the focal position of laser processing and make the focus on the upper surface of transparent materials.

5. The method for coating-based laser processing of transparent materials as claimed in claim 1, characterized in that: The method for removing the coating on the surface of the transparent material is as follows: soak the transparent material in an organic solvent for a period of time, then take it out and rinse it with clean water.

6. The method for coating-based laser processing of transparent materials according to claim 1, characterized in that: When the surface area of ​​the transparent material to be coated is greater than 1m 2 , the transparent material is immersed in the coating solution, then taken out and dried, and finally a coating is formed on the surface of the transparent material.

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