Method and apparatus for laser removal of metal layer in composite thin film material

Abstract

The application discloses a method and equipment for removing a metal layer in a composite film material by laser, and the method comprises the following steps: laser processing the composite film by adopting a galvanometer to control a laser according to a preset processing path, wherein the composite film comprises a polymer layer and a metal layer attached to the surface of the polymer layer; wherein the laser emits a laser beam to irradiate the side of the metal layer away from the polymer layer, the energy range of the laser is 1mJ-2.5mJ, the pulse width is 300ns-600ns, and the processing depth of the laser beam is 95%-100% of the thickness of the metal layer; and after the laser processing is completed, the metal layer is torn off along the preset processing path. The laser processing of the composite film by the galvanometer controlled laser can ensure that the tearing and pulling effect of the metal layer is good and the processing speed is fast after the laser processing, and the removal efficiency of the metal layer in the composite film material is greatly increased.

Description

Technical Field

[0001] This invention belongs to the field of laser cutting technology, specifically relating to a method and apparatus for laser removal of metal layers in composite thin film materials. Background Technology

[0002] Copper foil has low surface oxygen properties, allowing it to adhere to various substrates such as metals and insulating materials. It has a wide operating temperature range and is mainly used for electromagnetic shielding and antistatic purposes. By placing conductive copper foil on a substrate and combining it with a metal substrate, it exhibits excellent conductivity and electrical conductivity.

[0003] Currently, most copper thin-film processing involves directly rolling and spreading the raw metal material, then attaching and assembling other materials one by one according to a set procedure. Selective copper removal processing methods for pre-formed composite thin-film materials are rare. Composite thin-film materials consist of a metal thin-film layer (such as copper film) and a polymer layer, where the metal thin-film layer refers to a film of different metals or alloys. When composite thin-film materials are used in solar cells, the processing requirement is to peel off only the metal layer with the perforated pattern, retaining the polymer layer.

[0004] Traditional methods for processing composite film materials include CNC cutting or mechanical stamping. CNC cutting requires high-strength tools, which are costly and make it difficult to cut metal without damaging the polymer layer. Mechanical stamping, on the other hand, cannot accurately control the cutting depth of composite film materials, especially when the metal layer is only tens of micrometers deep. In addition, mechanical stamping is limited by factors such as the precision, type, and cost of the molds.

[0005] Currently, there are also methods for removing metal layers using laser processing (utilizing the absorption characteristics of lasers on different materials). Existing methods for removing metal layers (copper films, aluminum films, or copper-aluminum alloy films, etc.) using lasers involve etching lines into the metal layer. The lines are etched to a certain depth within the metal layer, and the depth of the processing area needs to be relatively uniform in order to peel off the metal layer. Figure 2 and Figure 4 As shown, this method has low processing efficiency and the tearing effect needs to be improved. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for laser removal of metal layers in composite thin film materials, thereby solving the problems of low efficiency and poor tearing effect in current laser removal of metal layers.

[0007] To achieve the above objectives, the present invention provides a method for laser removal of a metal layer in a composite thin film material, the method comprising the following steps:

[0008] According to the preset processing path, a galvanometer-controlled laser is used to perform laser processing on the composite film, which includes a polymer layer and a metal layer attached to the surface of the polymer layer.

[0009] In this process, the laser emits a laser beam to irradiate the side of the metal layer away from the polymer layer. The energy range of the laser is 1mJ to 2.5mJ, the pulse width is 300ns to 600ns, and the processing depth of the laser beam is 95% to 100% of the thickness of the metal layer.

[0010] After laser processing is completed, the metal layer is removed along the preset processing path.

[0011] Furthermore, the galvanometer speed is controlled to be 10 m / s to 20 m / s. Within this speed range, adjacent laser beam spots on the metal layer do not overlap.

[0012] Furthermore, the spacing between adjacent light spots is greater than d and less than 3d, where d is the size of a single light spot.

[0013] Furthermore, the laser has a frequency of 200 kHz to 400 kHz and a wavelength range of 915 to 1064 nm.

[0014] Furthermore, the focal point of the laser beam is located at the center of the metal layer.

[0015] Furthermore, when using a galvanometer-controlled laser to perform laser processing on the composite thin film, after the galvanometer-controlled laser emits light and moves the laser beam a first preset distance, the laser is turned off and then moved to a second preset distance before being emitted again to continue moving the laser beam a first preset distance. This process is repeated until the processing is completed.

[0016] Furthermore, the first preset distance is 200-500µm, and the jump distance is 100-300µm.

[0017] Furthermore, when using a galvanometer-controlled laser to perform laser processing on the composite film, the composite film is blown with gas, and the gas used for blowing is oxygen or air.

[0018] The present invention also provides a laser processing apparatus for processing metal layers in composite films. The apparatus uses the above-mentioned laser method for removing metal layers in composite film materials to remove the metal layers in the composite film materials.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] 1) The method for removing the metal layer in the composite thin film material by laser is proposed in this application. By controlling the processing depth of the laser beam to 95% to 100% of the thickness of the metal layer, and the energy range of the laser to 1mJ to 2.5mJ, and the pulse width to 300ns to 600ns (using a long pulse laser to increase the processing depth of a single spot), the removal efficiency of the metal layer in the composite thin film material is greatly increased. Moreover, the metal layer has a good tearing effect after processing, and the polymer layer is not damaged.

[0021] 2) This application adopts a laser beam jumping processing method controlled by a galvanometer, which can cut metal with a very fast laser processing speed, and can reduce the heat accumulation of metal layers and polymer materials, reduce material deformation, and avoid the problem of subsequent metal layer bonding with battery process; at the same time, the jumping processing method generates less waste dust and residual impurities, is cleaner, and is also conducive to the next process.

[0022] By increasing the speed of the galvanometer and processing the metal layer through a spot separation mode, the required depth for removing the metal layer can be achieved, while the metal layer can be easily torn off, thus improving efficiency. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the composition of the composite thin film material;

[0024] Figure 2 Microscopic images of traditional laser film removal;

[0025] Figure 3 This is a microscopic image of the laser film removal effect of the present invention;

[0026] Figure 4 3D diagram of a traditional membrane removal process;

[0027] Figure 5 The 3D image is cut for this invention;

[0028] Figure 6 The diagram shows the copper foil removal process using the dashed lines.

[0029] Figure 7 The light spot depth and size are those of Example 1;

[0030] Figure 8 The light spot depth and size are shown in Comparative Example 1;

[0031] Figure 9 The light spot depth and size are shown in Comparative Example 2;

[0032] Figure 10 The light spot depth and size are shown in Comparative Example 3. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0034] This invention uses infrared laser processing to process composite thin film materials (metal film and polymer film). By using an adjustable pulse width fiber laser and a longer pulse width parameter, the processing depth of a single spot is increased. In addition, by using a skip processing method, the metal layer on the hollowed-out pattern can be perfectly removed, improving processing capacity. At the same time, it reduces the heat effect area that will accumulate high heat during low-speed processing, reduces residual metal dust on the material surface, and avoids potential problems such as leakage.

[0035] This invention provides a method for laser removal of a metal layer in a composite thin film material, the method comprising:

[0036] Following a preset processing path, a galvanometer-controlled laser is used to laser process the composite film, which includes a polymer layer and a metal layer bonded to the surface of the polymer layer. Figure 1 As shown. A metal layer refers to a thin film of different metals or alloys.

[0037] During processing, the laser emits a laser beam to irradiate the side of the metal layer away from the polymer layer. The laser energy range is 1mJ to 2.5mJ, the pulse width is 300ns to 600ns, and the processing depth of the laser beam is 95% to 100% of the metal layer thickness.

[0038] After laser processing is complete, the metal layer is peeled off along a preset processing path. The preset processing path refers to the trajectory of the cutout pattern to be peeled off, for example... Figure 6 The path the laser needs to process, as shown in the diagram, is the trajectory of the pattern. During processing, a galvanometer controls the laser beam to scan this path. Regarding the pulse width, if the pulse width is too small, the interaction time between the laser and the metal is short, resulting in excessively high peak power. This causes the copper film (also called copper foil) to melt rapidly, creating a mirror-like surface that reflects most of the laser energy. This results in shallow processing depth, excessive tearing force, and a lot of residue. Conversely, if the pulse width is too large, the peak power does not reach the threshold, also leading to insufficient processing depth and excessive tearing force.

[0039] The laser removal method proposed in this application greatly increases the removal efficiency of the metal layer in the composite film material, and the metal layer has a good tearing effect after processing without damaging the polymer layer.

[0040] In this invention, the depth of laser scribing is either completely penetrating the metal layer or at least 95% of the processing depth. By adjusting the laser focus to the center of the metal layer, the entire metal layer is ensured to be at the laser focal depth, thus ensuring the optimal processing depth.

[0041] Furthermore, to improve film removal efficiency, a skip processing method is adopted, which greatly increases the processing speed of galvanometer scanning. The skip processing method is as follows: when using a galvanometer-controlled laser to laser process the composite thin film, the galvanometer controls the laser to emit light, moving the laser beam a first preset distance, then controls the laser to turn off, skips to a second preset distance, and then controls the laser to emit light again, continuing to move the laser beam a first preset distance, repeating this process until processing is complete. Figure 6 As shown in the figure. In this embodiment, the first preset distance is 200-500 μm, and the jump distance is 100-300 μm. By using this alternating combination of processing paths, it is possible to achieve low tearing stress and no tearing breakage. At the same time, the short distance of unprocessed metal layer itself has a certain tearable distance, followed by continuous light-emitting processing for a certain distance. After combination, the tearing distance and direction can be controlled. In addition, the jump processing method can reduce heat accumulation in metal layers such as copper film and polymer materials, reduce material deformation, and avoid subsequent battery bonding problems. At the same time, the jump processing method generates less waste dust and residual impurities, is cleaner, and is also beneficial to the next process.

[0042] When the laser emits light, the galvanometer speed is controlled at 10 m / s to 20 m / s. Within this speed range, adjacent laser beam spots on the metal layer do not overlap. By increasing the galvanometer speed and processing the metal layer through a spot-separation mode, the required depth for removing the metal layer can be achieved, while the metal layer can be easily torn off, thus improving efficiency. In this way, the combination of high galvanometer speed and skip-processing significantly improves processing efficiency and enhances the stability of subsequent processes.

[0043] Regarding galvanometer speed, if the speed is too low, the processing efficiency is low, the thermal effect is large, and there is more residual metal dust. Increasing the galvanometer speed within a certain range can shorten the processing time, but when the speed is too high, it will also lead to excessively large spot spacing, increasing the tearing resistance between adjacent holes in the metal layer. For example, at 10m / s-200khz-50um, the spots are tangent; by increasing the galvanometer speed to 14m / s, 20m / s, or even higher, the spacing between holes is increased. The spacing between adjacent spots is greater than d and less than 3d, where d is the size of a single spot. This not only improves processing efficiency but also facilitates the removal of the metal layer, ensuring tearing without breakage and meeting the required tearing force.

[0044] Furthermore, the frequency of the laser is 200kHz to 400kHz. If the frequency is too high, the single-point energy will be too low at the same power. If the frequency is too low, the processing efficiency will be low.

[0045] Furthermore, when using a galvanometer-controlled laser to process the composite thin film, air is blown onto the film, with either oxygen or air used. Blowing oxygen can accelerate the interaction between the laser and the metal, increasing the cutting depth and improving cutting efficiency. Because laser processing of the metal layer involves melting, oxidation, and plasma cloud formation, blowing air during processing enhances the reaction between the laser and the metal layer, removes some residue, effectively increasing the cutting depth while reducing residue buildup.

[0046] Since the copper foil (also called copper metal film) and the polymer layer are bonded together with adhesive, if the pulling force of the copper foil is greater than 1N, the copper foil in the processing area may break, resulting in residue in later processing. Removing this residue requires more manual labor, and the more residue there is, the greater the risk in later processing and the more detrimental it is to subsequent processes. Therefore, an important factor in evaluating the quality of metal layer removal is the pulling force of the copper foil. Only a pulling force of ≤0.75N is beneficial to the copper removal process after processing (the examples will illustrate that the pulling force of the copper foil meets the requirements when using the method of this application).

[0047] More specifically, a method for removing the metal layer in a composite thin film material using laser in this embodiment includes the following specific steps:

[0048] Based on the required cutout pattern to be removed, set the laser processing route, and use a galvanometer to scan the drawn route, such as... Figure 6 As shown.

[0049] The choice of laser spot size is also crucial; it's best to use a large beam expansion factor to maximize the beam size of a 915–1064 nm laser. Using the following optical formula, it can be seen that the larger the incident beam radius, the smaller the focused spot size of the field lens, and the greater the spot power density, thus maximizing the cutting depth.

[0050] Formula for focused spot radius:

[0051] Light spot power density formula:

[0052] In the formula, w 02(foc) The focal spot radius is represented by f, the focal length of the lens is represented by λ, and the laser wavelength is represented by M. 2 Indicates the laser mode parameters, w 01(in) ρ represents the radius of the laser spot incident on the lens surface, P represents the laser power density, and P represents the laser power.

[0053] This embodiment uses a fiber pulsed laser in the 915-1064nm band, which has a high absorption rate for metal films. At the same time, the transparent polymer film has extremely low absorption in the 915-1064nm band. The metal layer can be effectively removed by processing the metal layer, while protecting the polymer layer from damage.

[0054] Place the composite film material to be cut on the platform, with the metal side facing up as the processing surface. Activate the platform's suction to flatten the material. Simultaneously, turn on the oxygen blowing device and the dust extraction device, adjusting the pressure parameters of the devices. Oxygen blowing can accelerate the interaction between the laser and the metal, increasing the cutting depth and improving cutting efficiency. However, adding oxygen is not mandatory; ordinary clean air can be used instead.

[0055] By setting laser parameters and irradiating the copper film along a scanning path from left to right or top to bottom according to the processing route, and optimizing the processing sequence, processing can be performed along a reciprocating arc-shaped path from left to right or top to bottom. This can improve the scanning efficiency of the galvanometer, shorten the processing time, and increase processing efficiency. Specifically, the laser energy range is 1mJ to 2.5mJ, the laser frequency is 200kHz to 400kHz, the galvanometer speed is 10 to 20m / s, and the pulse width is 300 to 600ns.

[0056] After processing according to the processing route is completed, the metal layer is peeled off along the processing route. Figure 3 This is a microscopic image of the laser film removal effect of the present invention. Figure 5 The 3D image is cut for the present invention.

[0057] As another embodiment, the present invention also provides an apparatus for laser removal of metal layers in composite thin film materials. This apparatus employs the aforementioned method for laser removal of metal layers in composite thin film materials to remove the metal layers. Using this processing equipment to remove metal layers from composite thin film materials can significantly increase the removal efficiency of the metal layers, and the resulting metal layer exhibits good tear-off properties.

[0058] Experimental comparison:

[0059] Example 1: Using the same optical configuration and path, by adjusting the laser parameters, employing 95% laser power percentage, a frequency of 200 kHz, a pulse width of 50 ns, and performing three consecutive processes at a speed of 20 m / s, the spot size and width of the processed area were scanned using a 3D microscope. The results are as follows: Figure 7 As shown. Comparative Example 1 is similar to Example 1, except that the pulse width is changed to 100 ns. The laser power results are as follows. Figure 8 As shown. Comparative Example 2 is similar to Example 1, except that the pulse width is changed to 250 ns, and the results are as follows. Figure 9As shown. Comparative Example 3 is similar to Example 1, except that the pulse width is changed to 500 ns and the laser power is changed, and the results are as follows. Figure 10 As shown.

[0060] The experimental results of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 are shown in Table 1 below:

[0061] Table 1. Pulse Width Comparison Table

[0062]

[0063] As shown in Table 1, as the laser pulse width increases, the processing spot size of the metal layer decreases slightly, but the processing depth increases more significantly.

[0064] For conventional non-metallic materials (such as silicon and resin), the peak power P can be seen from the optical calculation formula. peak The same pulse width is inversely proportional:

[0065]

[0066] In the formula, P avg f represents the average power. rep τ represents the repetition frequency, τ represents the pulse width, and Δt represents the pulse period.

[0067] The peak power reflects the intensity of the laser's interaction with matter (physical and chemical) under normal circumstances; higher intensity is more conducive to interaction. That is, for conventional non-metallic materials, a smaller pulse width results in a larger peak power and a deeper processing depth. This invention uses an appropriate long pulse width range, which is more beneficial for the processing depth of copper foil and improves the efficiency of copper foil removal. For metallic materials, although a smaller pulse width results in a larger peak power, the processing depth is actually shallower, which is not conducive to processing thin metals (such as copper and aluminum). Due to the small pulse width, the interaction time between the laser and the metal is short, generating excessively high peak power, causing the copper foil to melt rapidly and reflect most of the laser energy.

[0068] To improve surface tearing efficiency, more embodiments are listed below.

[0069] Example A is similar to Example 1, except that it requires cutting a pattern from copper foil (jump processing), and then performing a copper foil tear test after processing the entire pattern. The processing is also performed three times, at a speed of 2.5 m / s, with laser parameters of 250 ns, 95% power, 200 kHz, 50% beam overlap, and a beam spacing of 25 μm. Comparative Example B is similar to Example A, with a laser parameter of 500 ns and other parameters identical. Example C uses a speed of 10 m / s, with laser parameters of 50 ns, 95% power, 200 kHz, and spaced beams with a beam spacing of 50 μm. Example D is similar to Example C, except the laser pulse width is changed to 100 ns, and other parameters remain the same. Example E is similar to Example C, except the laser pulse width is changed to 250 ns, and other parameters remain the same. Example F is similar to Example C, except the laser pulse width is changed to 500 ns, and other parameters remain the same. Comparative Example G is similar to Example F, with a laser pulse width of 500 ns, but the processing speed is increased to 14 m / s. The experimental results are shown in Table 2 below:

[0070] Table 2 Experimental Results

[0071]

[0072] The number of laser processing operations in the implementation case can be single or multiple, and there can be other combinations of spot spacing, spot size and depth.

[0073] As can be seen from Examples A and B, with a relatively low galvanometer speed and overlapping light spots, at the same overlap rate, a 500ns pulse width results in a smaller tearing force compared to a 250ns pulse width, which is much smaller than the most favorable tearing force (0.75N). Although Examples A and B can completely tear the light, the processing efficiency is low.

[0074] As can be seen from Examples C, D, and E, at the same frequency, with the same power and the same spot overlap rate, the tearing force is 250ns < 100ns < 50ns, indicating that the larger the pulse width, the smaller the tearing force, which is more conducive to tearing off the copper foil layer.

[0075] As can be seen from Examples F and G, by increasing the galvanometer speed and increasing the spot spacing, a spot spacing of 70µm at a pulse width of 500ns is just enough to completely peel off the copper foil layer while meeting the requirement of being less than the minimum favorable tearing force (0.75N). Although increasing the galvanometer speed within a certain range can shorten the processing time, if the galvanometer speed is too high, it will lead to an excessively large spot spacing, increasing the tearing resistance between adjacent holes. If the galvanometer speed is too low, the processing efficiency is low, the thermal effect is large, and there is more residual metal dust.

[0076] Examples H, I, and J show that when the laser speed, spot spacing, frequency, and pulse width are consistent, increasing the single-point energy of the laser reduces the tearing force on the copper foil in the cut-out area. However, lasers with the same frequency and pulse width but different single-point energies can vary drastically in cost, sometimes by several times.

[0077] This application proposes a method for laser removal of metal layers from composite thin film materials. Compared with traditional methods using cutting tools and stamping dies, it is not limited by sample size, shape, thickness, or cutting requirements. It is a non-contact metal cutting method with good appearance, no contact damage, simple processing, and avoids contamination of copper foil surfaces. The method uses laser-matched digital galvanometer cutting, which offers higher software controllability, higher cutting precision, and a high degree of automation. Compared with other laser processing methods, it greatly increases the removal efficiency of metal layers from composite thin film materials, and the metal layer has a good tear-off effect after processing without damaging the polymer layer.

[0078] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0079] Those skilled in the art will readily understand that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for laser removal of a metal layer in a composite thin film material, characterized in that, The method includes the following steps: A laser processing path is set according to the required cutout pattern to be torn off, wherein the laser processing path is the trajectory of the cutout pattern to be torn off; According to the laser processing path, a galvanometer-controlled laser is used to perform laser processing on the composite film, which includes a polymer layer and a metal layer attached to the surface of the polymer layer. The laser emits a laser beam to irradiate the side of the metal layer away from the polymer layer. The laser's energy range is 1 mJ to 2.5 mJ, its pulse width is 300 ns to 600 ns, and the processing depth of the laser beam is 95% to 100% of the metal layer thickness. The galvanometer speed is controlled to be 10 m / s to 20 m / s. Within this speed range, adjacent laser beam spots on the metal layer do not overlap. The distance between adjacent laser beam spots is greater than d and less than 3d, where d is the size of a single laser beam spot. When using a galvanometer-controlled laser to perform laser processing on a composite thin film, the galvanometer controls the laser to emit light, moving the laser beam a first preset distance. Then, the laser is turned off, and the process jumps to a second preset distance before the laser is emitting light again, continuing to move the laser beam a first preset distance. This process is repeated until the processing is complete. After laser processing is completed, the metal layer is removed along the laser processing path.

2. The method for laser removal of the metal layer in a composite thin film material according to claim 1, characterized in that, The laser has a frequency of 200 kHz to 400 kHz and a wavelength range of 915 to 1064 nm.

3. The method for laser removal of the metal layer in a composite thin film material according to claim 1, characterized in that, The focal point of the laser beam is located at the center of the metal layer.

4. The method for laser removal of the metal layer in a composite thin film material according to claim 1, characterized in that, The first preset distance is 200~500um, and the jump distance is 100~300um.

5. The method for laser removal of the metal layer in a composite thin film material according to claim 1, characterized in that, When using a galvanometer-controlled laser to perform laser processing on the composite film, the composite film is blown with gas, and the gas used for blowing is oxygen or air.

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