A laser processing method for an AR film layer on a surface of an ITO film layer and an optical film group structure

Abstract

The application provides a laser processing method for an AR film layer on a surface of an ITO film layer, comprising the following steps: S1, cleaning a surface of a workpiece to be processed, and designing positions of the AR film layer to be removed on the surface of the workpiece to be processed according to a required conductor / electrode position distribution on the workpiece to be processed; and S2, focusing a laser beam on the designed positions of the AR film layer on the surface of the workpiece to be processed to process a plurality of micropores, so that the ITO film layer under the AR film layer is exposed at the micropores. The application adopts a pulsed laser to interact with the AR film layer in a very short time, to form micropores on the surface of the AR film layer after removal, to vaporize the AR film layer at the center of the micropores by instantaneous high energy, and to form a circle of exposed and undamaged conductive areas of the ITO film layer at the edge of the micropores due to thermal influence, so that the AR film layer can be removed, the ITO film layer can be exposed, the conductive capacity of the ITO film layer can be retained, the strength of a substrate under the ITO film layer is not affected, and the function and use are not affected.

Description

Technical Field

[0001] This invention belongs to the field of laser micromachining technology, specifically relating to a laser processing method and optical film structure for an AR film layer on the surface of an ITO film layer. Background Technology

[0002] Indium tin oxide (ITO) films possess high conductivity, high visible light transmittance, high mechanical hardness, and good chemical stability, making them the most commonly used thin-film material for transparent electrodes in liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescent displays (EL / OLEDs), touchscreens, solar cells, and other electronic instruments. Anti-reflective coating (AR) films have very high light transmittance (over 95%) and are commonly used protective materials for the outer surfaces of screens, lenses, and other components. In applications such as the optical windows of lidar systems, ITO films are often covered with AR films. The ITO film provides conductivity, while the AR film provides insulation. Depending on the location of the conductors / electrodes, the ITO film at these locations needs to be exposed, thus requiring the removal of the AR film layer from the ITO film surface.

[0003] Traditional methods for removing the AR film from the surface of the ITO film include chemical etching, fixture masking, continuous laser processing, and pulsed laser removal. Among these methods, chemical etching and fixture masking are complicated, time-consuming, have poor dimensional accuracy, and are not environmentally friendly. Continuous laser processing and pulsed laser removal can damage the underlying ITO film while removing the AR film, causing discoloration and loss of conductivity in the ITO film, and may even damage the substrate beneath the ITO film. Summary of the Invention

[0004] The purpose of this invention is to provide a laser processing method for AR film layers on the surface of ITO film layers, which can at least solve some of the defects existing in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A laser processing method for an AR film layer on the surface of an ITO film includes the following steps:

[0007] S1. Clean the surface of the workpiece and design the location of the AR film layer to be removed from the surface of the workpiece based on the required distribution of wires / electrodes on the workpiece.

[0008] S2. Using a laser beam focused on the AR film layer on the surface of the workpiece, several micro-holes are formed, so that the ITO film layer under the AR film layer is exposed at the micro-holes, and a conductive area with exposed and undamaged ITO film layer is formed at the edge of the micro-holes under the influence of heat.

[0009] Furthermore, the laser processing method for the AR film layer on the surface of the ITO film layer also includes step S3, which involves annealing the workpiece after step S2, screen printing silver paste, and performing resistance testing.

[0010] Furthermore, in step S1, a marking pattern is created using drawing software for the AR film layer to be removed on the workpiece, and the marking pattern to be processed is imported through the laser control system. Internal filling is performed first, and the filling method is unidirectional filling with a filling line spacing of 30-45 μm and a filling angle of 0° or 90°.

[0011] Furthermore, the laser beam has a wavelength of 355nm, a single pulse energy of 1.9–2.3μJ, and a dot pitch greater than 3 / 2 times the focused beam diameter.

[0012] Furthermore, the laser beam is a Gaussian beam, or a square or circular flat-top beam shaped by DOE.

[0013] Furthermore, the laser beam passes sequentially through a reflector, a beam expander, a galvanometer, and a field mirror along the external optical path before being focused onto the surface of the workpiece. The beam expander has a beam expansion factor of 1 to 4 times.

[0014] Furthermore, in step S2, the processing position of the workpiece is located by using a weak laser light indicator or a red light positioning method.

[0015] Furthermore, the micropores are square, circular, or elliptical in shape, and their size is 20–25 μm.

[0016] In addition, the present invention also provides an optical film assembly structure, which is processed by the laser processing method described above.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] (1) The laser processing method for AR film on the surface of ITO film provided by the present invention uses pulsed laser to interact with AR film in a very short time. After removal, micropores are formed on the surface of AR film. The instantaneous high energy vaporizes AR film in the center of micropore. Due to thermal effects, a conductive area of ​​exposed and undamaged ITO film is formed at the edge of micropore. Thus, the conductivity of ITO film can be preserved while removing AR film and exposing ITO film, without affecting the strength of the substrate under ITO film, and without affecting function and use.

[0019] (2) The laser processing method for AR film on ITO film surface provided by this invention can focus the spot size to the micron level, with high dimensional accuracy and non-contact processing. The laser removes the material through thermal effect, which is environmentally friendly and energy-free, and has a higher cost performance.

[0020] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the laser processing method of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure for laser removal of AR film from ITO film surface in this invention;

[0023] Figure 3 This is a microscopic image showing the effect of removing the AR film layer from the entire surface using a pulsed laser in Embodiment 1 of the present invention;

[0024] Figure 4 This is a microscopic image of the metallographic microscope showing the removal of the AR film layer using the laser processing method of the present invention in Embodiment 1 of the present invention;

[0025] Figure 5 This is a micropore structure diagram after pulsed laser removal, magnified 1000 times using a scanning electron microscope in Embodiment 1 of the present invention.

[0026] Explanation of reference numerals in the attached figures: 1. Laser beam; 2. AR film; 3. ITO film; 4. Substrate. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an abutting connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. In the description of this invention, unless otherwise stated, "a plurality of" or "several" means two or more.

[0030] like Figure 1 and Figure 2 As shown, this embodiment provides a laser processing method for an AR film layer on the surface of an ITO film, including the following steps:

[0031] S1. Clean the surface of the workpiece to be processed, wherein the workpiece includes a substrate 4, an ITO film layer 3, and an AR film layer 2 arranged sequentially from bottom to top. The specific method for cleaning the surface of the workpiece to be processed can be, but is not limited to, wiping the surface with alcohol to ensure that the surface is free of dirt and to avoid affecting the processing effect.

[0032] S2. Based on the required wire / electrode position distribution on the workpiece, design the area on the surface of the workpiece where AR film 2 needs to be removed.

[0033] Specifically, for the area where AR film layer 2 needs to be removed on the workpiece, a marking pattern can be created using drawing software. The marking pattern to be processed is then imported into the laser control system. Internal filling is performed first, and the filling method is unidirectional filling without intersection. The spacing between filling lines is 30-45um, and the specific value is determined by the size of the focused spot. The filling angle is 0° or 90°.

[0034] S3. Move the workpiece to be processed to the designated processing position through the motion control system, adjust the external optical path to focus the laser beam 1, and then adjust the motion control system to make the processing area be positioned at the laser focal point.

[0035] Specifically, the motion control system includes a marking platform and an X / Y / Z three-axis drive assembly that drives the marking platform to move along the X / Y / Z axes. The cleaned workpiece is placed on the marking platform. The X and Y axes of the X / Y / Z three-axis drive assembly drive the marking platform to the designated processing position; the Z axis drive of the X / Y / Z three-axis drive assembly ensures that the laser focus falls on the surface of the area to be processed. The specific structure and working principle of the X / Y / Z three-axis drive assembly are existing technologies and will not be described in detail here.

[0036] The external optical path includes a reflector, a galvanometer, and a field mirror arranged sequentially along the optical path. The laser beam 1 emitted by the laser passes through the reflector, galvanometer, and field mirror sequentially and is focused onto the surface of the workpiece. During this process, after the laser beam 1 enters the galvanometer, there are two mirrors inside the galvanometer. The galvanometer controller controls the two mirrors to deflect, thereby changing the position of the laser beam 1 on the sample. Optimally, a beam expander is also provided in the external optical path, located between the reflector and the galvanometer. The beam expander changes the size of the focused spot of the laser beam by changing the beam expansion magnification. Combined with the aforementioned reflector, galvanometer, and field mirror, their sequential positions can be adjusted according to design requirements. The beam expansion magnification of the beam expander is preferably 1 to 4 times. The higher the magnification, the smaller the focused spot can be, producing different processing effects to meet the removal requirements of different AR film thicknesses.

[0037] Furthermore, the processing position of the workpiece can be located by means of weak laser light indication or red light positioning.

[0038] S4. Adjust the laser processing parameters and use the laser beam 1 to focus on the AR film layer 2 on the surface of the workpiece at the designed position. Mark the workpiece according to the marking pattern to form several micro-holes, so that the ITO film layer 3 under the AR film layer 2 is exposed at the micro-holes, and a conductive area with exposed and undamaged ITO film layer is formed at the edge of the micro-holes under the influence of heat.

[0039] Specifically, in this embodiment, a pulsed laser is used, and the laser beam 1 is a Gaussian beam, or a square or circular flat-top beam shaped by DOE. The laser wavelength is 355nm, the single-pulse energy is 1.9–2.3μJ, the dot pitch is 30–45µm, and the processing is performed once, thereby forming dense micropores on the surface of the AR film layer 2 of the workpiece. The shape of the micropores can be, but is not limited to, square, circular, elliptical, etc., and their size is 20–25µm. The single-pulse energy is adjusted by changing the laser frequency and laser power, and the dot pitch is adjusted by changing the filler line spacing and processing speed, and the dot pitch is greater than 3 / 2 times the focused beam diameter. Different parameters are selected according to the requirements of processing accuracy, processing time, and the thickness of the AR film layer to be removed, so as to improve processing efficiency and processing quality.

[0040] In this embodiment, the pulsed laser of the pulsed laser is focused to a micrometer-scale size through an external optical path. At the same time, the pulsed laser interacts with the AR film layer 2 on the surface in a very short time. The instantaneous high energy vaporizes the AR film layer 2 at the center of the micropore. Due to thermal effects, a conductive area with an exposed and undamaged ITO film layer 3 is formed at the edge of the micropore.

[0041] Furthermore, after the AR film layer 2 is laser-processed, the workpiece is annealed. Silver paste is then screen-printed onto the microporous areas on the surface of the AR film layer 2, and a resistance test is performed to check whether the conductivity of the exposed ITO film layer 3 after removing the AR film layer 2 has recovered to the same level as the conductivity of the bottom ITO film layer 3. Because the microporous areas of the AR film layer 2 have multiple micropores, the surface of these microporous areas has an uneven structure. This surface roughness is greater than that of the smooth conductive film layer 3 after removing the entire AR film layer 2. During screen printing, the silver paste adheres more firmly to the ITO film layer 3, reducing the possibility of detachment and decreasing contact resistance.

[0042] The effects of the laser processing method for AR film on the surface of ITO film of the present invention are illustrated below through specific embodiments. Example 1

[0043] In this embodiment, two parts A and B from the same batch are subjected to laser processing. The AR film layer on the surface of part A is removed by a pulsed laser, while the laser processing method of the present invention is used on part B, that is, the AR film layer is processed by a pulsed laser through a method of marking dense micro-holes.

[0044] The microscopic effects of the surface of workpiece A after laser processing are as follows: Figure 3 As shown. By Figure 3 As can be seen, after the entire AR film layer was removed, the ITO film layer changed color, and some areas exposed the substrate (as shown by the circled area I in the figure). This indicates that using a pulsed laser to remove the entire AR film layer damaged the underlying ITO film layer, and may even damage the substrate beneath the ITO film layer, resulting in reduced strength of the workpiece. After annealing and removing the areas where silver paste was applied to the laser-processed workpiece A, the resistance of its ITO film layer was tested. The results showed that its resistance was higher than that of the original ITO film layer.

[0045] The microscopic effect of the surface B of the workpiece after laser processing is shown in the metallographic microscope. Figure 4 As shown, the microstructure of the surface of workpiece B, magnified 1000 times using a scanning electron microscope, is as follows: Figure 5 As shown. By Figure 4 and Figure 5 It can be seen that the laser micron-sized focused beam interacts with the surface AR film layer in a very short time. After the instantaneous high energy vaporizes the AR film layer at the center of the micropore, the central region of the micropore (i.e. Figure 4 The ITO film in part a) has some damage, but due to thermal effects, a conductive region with exposed and undamaged ITO film will form at the edge of the micropores (i.e., Figure 4(Part b). After annealing and removing the screen-printed silver paste from the laser-processed part B, the resistance of its ITO film layer was tested. The results showed that it had the same conductivity as the original lower ITO film layer, and did not affect the strength of the substrate below the ITO film layer, nor did it affect the function or use. Example 2

[0046] This embodiment provides a laser processing method for an AR film layer on the surface of an ITO film. The specific operation process is as follows:

[0047] 1. Pre-treatment of the workpiece: Wipe the sample with alcohol to ensure that its surface is free of dirt.

[0048] 2. Set up the test platform: Select an ultraviolet nanosecond laser, set the wavelength to 355nm, and preheat it. Fix the pre-treated workpiece on the marking platform with the surface to be processed facing upwards. Adjust the external optical path and motion control system so that the laser beam is focused on the surface of the area to be processed after passing through the reflector, beam expander, galvanometer, and field lens. Perform positive focus processing, adjust the magnification of the beam expander to 2x, and the focal length of the field lens to 355mm.

[0049] 3. Editing the drawing file: Create the marking drawing file. Import the two lead wire patterns to be processed through the laser control system. First, perform internal filling. The filling method is unidirectional filling with a filling line spacing of 40um and a filling angle of 90 degrees.

[0050] 4. Set the laser processing parameters: Based on the fill line spacing, frequency 40kHz, set the marking speed to 1600mm / s, field lens power to 82mW (i.e., single pulse energy 2.1μJ), micro-hole spacing to 40um, and marking times to 1.

[0051] 5. Positioning: Activate the laser weak light indicator function to position the laser at the processing location.

[0052] 6. Marking: Laser marking to mark dense micropores.

[0053] 7. Setting up the leads: After annealing (approximately 300℃ for 2 hours), silver paste screen printing, and drying, the resistance between the two leads was tested using a multimeter. A total of 10 samples were tested, and the results are shown in Table 1.

[0054] Table 1:

[0055]

[0056] Furthermore, this invention also provides an optical film assembly structure, fabricated using the aforementioned laser processing method for an AR film layer on the surface of an ITO film layer. Specifically, it includes an ITO film layer 3 and an AR film layer 2 covering the surface of the ITO film layer 3. Depending on the arrangement of the wires / electrodes, the AR film layer 2 has a complete area and a microporous area. For portions where wires / electrodes do not need to be laid, the complete area of ​​the AR film layer 2 completely covers the ITO film layer 3, providing insulation. For portions where wires / electrodes need to be laid, the microporous area of ​​the AR film layer 2 covers this portion of the ITO film layer 3. The surface of the microporous area of ​​the AR film layer 2 is processed using the laser processing method of this invention to form several spaced micropores. These micropores penetrate the AR film layer 2, and the ITO film layer 3 located in the microporous area of ​​the AR film layer 2 is electrically connected to the outside through these micropores, providing conductivity. Compared to existing structures that completely remove the AR film layer 2 for portions requiring wire / electrode placement, this optical film assembly structure reduces damage to the ITO film layer 3.

[0057] In summary, the laser processing method for AR film on the surface of ITO film provided by this invention achieves the removal of AR film on the surface of ITO film by selecting a laser, adjusting the beam expander, selecting a lens, and adjusting parameters such as single pulse energy, dot pitch, and filling method. The pulsed laser emitted by the pulsed laser interacts with the surface AR film in a very short time, forming dense micropores on the AR film surface after removal. The instantaneous high energy vaporizes the AR film at the center of the micropores. Due to thermal effects, a conductive area with exposed and undamaged ITO film is formed at the edge of the micropores. After annealing and screen printing, it has the same conductivity as the original underlying ITO film and does not affect the strength of the substrate below the ITO film, nor does it affect the function and use. It effectively solves the problems of complicated processes, poor dimensional accuracy, and environmental unfriendliness of traditional chemical etching processing, and also solves the problems of damage to ITO and increased resistance in laser full-surface removal processing.

[0058] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A laser processing method for an AR film layer on the surface of an ITO film, characterized in that, Includes the following steps: S1. Clean the surface of the workpiece and design the location of the AR film layer to be removed from the surface of the workpiece based on the required distribution of wires / electrodes on the workpiece. S2. A laser beam is focused onto the AR film layer on the surface of the workpiece to form several microholes, exposing the ITO film layer beneath the AR film layer at the microholes. A conductive area with exposed and undamaged ITO film layer is formed at the edge of the microholes under heat influence. The laser beam has a wavelength of 355nm, a single pulse energy of 1.9–2.3μJ, and a dot pitch greater than 3 / 2 times the diameter of the focused beam. The microholes are square, circular, or elliptical in shape, with a size of 20–25µm.

2. The laser processing method for the AR film layer on the surface of the ITO film layer as described in claim 1, characterized in that, It also includes step S3, which involves annealing and silkscreening the workpiece after step S2, and then performing a resistance test.

3. The laser processing method for the AR film layer on the surface of the ITO film layer as described in claim 1, characterized in that, In step S1, a marking pattern is created using drawing software for the AR film layer to be removed on the workpiece. The marking pattern to be processed is then imported into the laser control system. Internal filling is performed first, and the filling method is unidirectional filling with a filling line spacing of 30-45 μm and a filling angle of 0° or 90°.

4. The laser processing method for the AR film layer on the surface of the ITO film layer as described in claim 1, characterized in that, The laser beam is a Gaussian beam, or a square or circular flat-top beam shaped by DOE.

5. The laser processing method for the AR film layer on the surface of the ITO film layer as described in claim 1, characterized in that, The laser beam passes sequentially through a reflector, a beam expander, a galvanometer, and a field mirror along the external optical path before being focused onto the surface of the workpiece. The beam expander has a beam expansion factor of 1 to 4 times.

6. The laser processing method for the AR film layer on the surface of the ITO film layer as described in claim 1, characterized in that, In step S2, the processing position of the workpiece is located by using a weak laser light indicator or a red light positioning method.

7. An optical film module structure, characterized in that, It is processed using the laser processing method described in any one of claims 1 to 6.

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