A laser etching apparatus and method

Abstract

The application provides a laser etching device and method, relates to the technical field of laser processing, and the device comprises a pulse laser device and a base for carrying a battery. The pulse laser device is used for emitting a plurality of laser sub-beams towards the battery. The surface of the battery has at least one electrode line preset area. After the plurality of laser sub-beams are emitted, a plurality of focused light spots are formed in the same electrode line preset area. The plurality of focused light spots are spaced apart from each other. The pulse laser device is used for controlling the plurality of focused light spots to scan the battery along the same electrode line preset area. The arrangement direction of at least two focused light spots in the plurality of focused light spots is arranged at an acute angle with the scanning direction of the plurality of focused light spots. When the plurality of focused light spots satisfying the above conditions are used to perform laser etching on the same electrode line preset area, the spacing between adjacent etching holes is increased, the etching width is optimized, the seed crystal area is increased, the series resistance is reduced, the fill factor is improved, and the photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of laser processing technology, and more specifically, to a laser etching apparatus and method. Background Technology

[0002] Solar cells are receiving increasing attention in the photovoltaic field. To facilitate timely current output, solar cells typically require electrode grid lines. In the process of fabricating electrode grid lines, a predetermined area of ​​the electrode grid lines needs to be laser-etched, and then the electrode grid lines are fabricated within that area through seeding and electroplating.

[0003] Current laser etching methods typically utilize a single laser beam to form a single spot within a predetermined area of ​​the electrode grid line, and employ a galvanometer for single-line processing. In this method, the subsequent seed area depends on the size and number of laser spots. For example, with a fixed number of spots, a larger spot size results in a larger seed area, but also a larger area damaged by laser etching. Conversely, reducing the spot size can decrease the damaged area, but it leads to a smaller seed area, which is detrimental to the stability of the electrode grid line. Similarly, with a fixed spot size, a larger number of spots results in a larger seed area, but also a larger area damaged by laser etching. Reducing the number of spots can decrease the damaged area, but it leads to a smaller seed area, which is detrimental to the stability of the electrode grid line. Summary of the Invention

[0004] The purpose of this application is to provide a laser etching apparatus and method to address the shortcomings of the prior art.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0006] In one aspect of this application, a laser etching apparatus is provided, including a pulsed laser device and a base for supporting a battery;

[0007] The pulsed laser device is used to emit multiple laser sub-beams toward the battery. The battery surface has at least one electrode line preset area. After the multiple laser sub-beams are emitted, they form multiple focused light spots located in the same electrode line preset area, and the multiple focused light spots are spaced apart from each other.

[0008] The pulsed laser device is used to control multiple focused light spots to scan the battery along a preset area of ​​the same electrode line, and the arrangement direction of at least two of the multiple focused light spots is set at an acute angle to the scanning direction of the multiple focused light spots.

[0009] Optionally, multiple focused light spots are arranged in a straight line.

[0010] Optionally, the width of the multiple focused spots along the vertical scanning direction is the etching width, and the etching width is less than or equal to 0.12 mm.

[0011] Optionally, the etching width is 0.07 mm to 0.1 mm, or 0.08 mm to 0.1 mm, or 0.04 mm to 0.12 mm.

[0012] Optionally, the number of multiple focused spots is two, and / or the acute angle is 30° to 60°.

[0013] Optionally, when the number of multiple focused light spots is two and the acute angle is 30°, in the etching holes formed on the battery by the focused light spots, any two etching holes with the smallest distance between them are distributed in an isosceles triangle.

[0014] When there are two focused light spots and the acute angle is 60°, the etched holes formed by the focused light spots on the battery will form an equilateral triangle distribution with the two etched holes with the smallest distance between them.

[0015] Optionally, among multiple focused spots (multiple focused spots formed by a single irradiation), the center-to-center distance between adjacent focused spots in the scanning direction is the center-to-center distance within the group;

[0016] In two adjacent irradiations, the minimum center-to-center distance between any of the focused light spots in the previous irradiation and any of the focused light spots in the subsequent irradiation in the scanning direction is the inter-group center-to-center distance.

[0017] The center-to-center distance within a group is greater than or equal to the center-to-center distance between groups.

[0018] Optionally, the diameter of the focused spot is 20 μm to 36 μm;

[0019] And / or, in multiple focused spots, the center-to-center distance between adjacent focused spots in the scanning direction is 40 μm to 100 μm;

[0020] And / or, in two adjacent irradiations, the minimum center-to-center distance between any of the focused spots in the previous irradiation and any of the focused spots in the subsequent irradiation in the scanning direction is 40 μm to 100 μm.

[0021] Optionally, the frequency of the pulsed laser device is from 500 kHz to 1000 kHz.

[0022] Optionally, the pulsed laser device includes a scanning module and a pulsed laser module and a beam splitting module arranged sequentially along the optical path. The laser beam emitted by the pulsed laser module is split into multiple laser sub-beams by the beam splitting module. The scanning module is used to modulate the multiple laser sub-beams to control multiple focused spots to scan the battery along the same electrode line in a preset area.

[0023] Optionally, the pulsed laser device further includes an angle adjustment module, which is driven and connected to the beam splitting module. The angle adjustment module drives the beam splitting module to rotate to adjust the angle between the arrangement direction of at least two focused spots and the scanning direction of multiple focused spots.

[0024] Optionally, the pulsed laser device also includes multiple beam shaping mirrors. The laser beam has different laser phases after being modulated by different beam shaping mirrors. The multiple beam shaping mirrors are used to replace each other in the optical path.

[0025] Alternatively, the pulsed laser device may also include a spatial beam modulator located in the optical path.

[0026] Optionally, the scanning module includes a galvanometer module and a field lens located in the optical path, with the galvanometer module located on the light-emitting side of the beam splitter module and the field lens located on the light-emitting side of the galvanometer module.

[0027] Alternatively, the scanning module can be a driving module, which is connected to the base drive, or the driving module can be connected to the pulsed laser module and the beam splitter module.

[0028] Optionally, multiple etched holes formed on the battery by the same focused light spot are spaced apart from each other, and etched holes formed on the battery by different focused light spots are spaced apart from each other.

[0029] Optionally, the electrode line preset area is either the main grid line preset area or the fine grid line preset area.

[0030] Another aspect of this application provides a laser etching method, the method comprising:

[0031] Multiple focused light spots are formed within a preset area along the same electrode line on the surface of the battery using multiple laser sub-beams, wherein the multiple focused light spots are spaced apart from each other;

[0032] Multiple focused light spots are controlled to scan the battery along a preset area of ​​the same electrode line, wherein at least two of the multiple focused light spots are arranged at an acute angle to the scanning direction of the multiple focused light spots.

[0033] The beneficial effects of this application include:

[0034] This application provides a laser etching apparatus and method. The apparatus includes a pulsed laser device and a base for supporting a battery. The pulsed laser device emits multiple laser sub-beams toward the battery. The battery surface has at least one electrode line with a predetermined region. After the multiple laser sub-beams are emitted, they form multiple focused light spots located within the same electrode line's predetermined region, with the multiple focused light spots spaced apart from each other. The pulsed laser device controls the multiple focused light spots to scan the battery along the same electrode line's predetermined region, and the arrangement direction of at least two of the multiple focused light spots forms an acute angle with the scanning direction of the multiple focused light spots. This application utilizes multiple focused light spots satisfying the aforementioned conditions to perform laser etching on the same electrode line's predetermined region, increasing the spacing between adjacent etched holes, optimizing the etching width, increasing the seed crystal area, reducing series resistance, improving the fill factor, and enhancing photoelectric conversion efficiency. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of an existing laser system.

[0037] Figure 2 This is a schematic diagram of a battery after etching using an existing laser system.

[0038] Figure 3 This is one of the structural schematic diagrams of a laser etching apparatus provided in an embodiment of this application;

[0039] Figure 4 This is one of the schematic diagrams of a focused light spot on the surface of a battery provided in an embodiment of this application;

[0040] Figure 5 This is a schematic diagram of the focused light spot after two irradiations provided in an embodiment of this application;

[0041] Figure 6 This is one of the schematic diagrams of etched holes on the surface of a battery provided in an embodiment of this application;

[0042] Figure 7 This is a second schematic diagram of a focused light spot on the surface of a battery, provided in an embodiment of this application.

[0043] Figure 8 This is the third schematic diagram of a focused light spot on the surface of a battery provided in this application embodiment;

[0044] Figure 9This is a second schematic diagram of a laser etching apparatus provided in an embodiment of this application;

[0045] Figure 10 This is a schematic flowchart of a laser etching method provided in an embodiment of this application. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. It should be noted that, unless otherwise specified, the various features in the embodiments of this application can be combined with each other, and the combined embodiments are still within the protection scope of this application.

[0048] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application 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, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0049] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0050] Please combine Figure 1 and Figure 2This illustrates a conventional laser etching scheme. A battery 20 is placed below a laser system 10, and the surface of the battery 20 has a predetermined area for electrode grid lines. A single laser beam 11 emitted by the laser system forms a single spot within the predetermined area of ​​the electrode grid lines on the surface of the battery 20. With the help of a galvanometer built into the laser system, the spot scans the predetermined area of ​​the electrode grid lines point by point along the scanning direction a, i.e., single-line processing, thereby forming a pattern such as... Figure 2 The etching trace 21 is located on the surface of the battery 20.

[0051] Based on existing laser etching methods, it is known that when a single laser spot irradiates the surface of the battery 20, it will form an etching hole 22 within its irradiation range. Therefore, multiple etching holes 22 will exist on the etching trajectory 21 formed along the scanning direction. The size of the laser spot also affects the size of the etching holes. For ease of understanding, the etching width is defined as the width between the upper and lower boundaries of the entire structure formed by all etching holes in the vertical scanning direction. Therefore, in existing laser etching methods, the etching width w is... Figure 2 The width of a single etched hole 22 shown is in the vertical scanning direction.

[0052] Since the subsequent seeding process requires seeding through etched holes to form a seed layer, with a fixed number of laser spots, a larger laser spot (wider etching width w) results in a larger etching hole area and consequently a larger seed crystal area. This allows for better contact between the seed layer and the gate metal formed on top of it. However, it's important to understand that a larger laser spot corresponds to a larger etching hole area. Because laser etching causes some damage to the etched areas of the battery, the damaged area is also larger, resulting in a smaller remaining undamaged area (the effective photoelectric conversion area), which is detrimental to improving photoelectric conversion efficiency. Conversely, a smaller laser spot (narrower etching width w) results in a smaller seed crystal area. While this reduces the damaged area, it inevitably makes it difficult for the seed layer to form good contact with the gate metal formed on top of it, leading to easy detachment. Therefore, existing laser etching methods struggle to achieve an effective balance between photoelectric conversion efficiency and the formation of electrode gate lines.

[0053] Based on this, one aspect of the embodiments of this application provides a laser etching apparatus, such as... Figure 3 As shown, it includes a pulsed laser device 100 and a base (not shown) for supporting a battery 200.

[0054] To facilitate understanding of the technical solution of this application, the battery is first introduced: In order to facilitate connection with external circuits, electrodes are usually made on the front and / or back of the battery 200. The specific position of the electrodes can be reasonably selected according to the type of battery. For example, when the battery is a back contact solar cell (BC battery), the electrodes to be made are located on the back of the battery; while when the battery is a non-back contact solar cell, the electrodes to be made can be distributed on the front and back of the battery, etc.

[0055] An electrode can be composed of several electrode lines. For example, an electrode can be an electrode grid line, which can be composed of several electrode lines. Specifically, the several electrode lines may include several main grid lines and / or several fine grid lines. During the fabrication of the electrode lines, for a battery 200 with surface passivation or protection, it is necessary to first perform laser etching on the surface layers of the battery 200 to open the passivation or protection layers. After fabricating the electrode lines in the opened areas, the electrode lines can easily pass through the passivation or protection layers and make good contact with the internal functional layers of the battery 200. In this embodiment, the laser etching of this application etches the passivation layer on the surface of the solar cell down to the functional layer (e.g., doped polycrystalline silicon / amorphous silicon / microcrystalline silicon layers, etc.) to form etched holes, ensuring good contact between the electrode layer and the functional layer during subsequent electrode fabrication.

[0056] For ease of description, the area on the surface of battery 200 where electrode lines need to be fabricated is defined as the electrode line preset area, for example... Figure 4 As shown, the area within the dotted line frame can serve as a preset area 201 for an electrode line. It should also be understood that the surface of the battery 200 can have one or more preset areas 201 for electrode lines, and these preset areas 201 can be connected, separated, or intersecting.

[0057] Based on the above description, when manufacturing electrodes, the battery needs to be laser etched using a laser etching device, which will be described below with reference to the accompanying drawings.

[0058] like Figure 3 As shown, the pulsed laser device can emit multiple laser sub-beams 101 (each laser sub-beam 101 is a pulsed laser) when laser etching is required, and these multiple laser sub-beams propagate towards the battery placed inside the substrate. It should be understood that the number of laser sub-beams 101 includes two or more, and the specific number can be reasonably selected according to actual needs, for example... Figure 3 As shown, the pulsed laser device emits two laser sub-beams 101, and both laser sub-beams 101 irradiate the surface of the battery 200.

[0059] Each laser sub-beam irradiating the battery surface can form a focused spot on the battery surface. Therefore, multiple laser sub-beams can form multiple focused spots on the battery surface in a single irradiation. For ease of understanding, the multiple focused spots formed in a single irradiation can also be called a focused spot group. For example, combining... Figure 3 and Figure 4 As shown, when there are two laser sub-beams 101, the two laser sub-beams 101 form a focused spot group 102 on the surface of the battery, including focused spots 102a and 102b.

[0060] To optimize laser etching results, it is necessary to ensure that all focused spots formed by multiple laser sub-beams are located within a preset area along the same electrode line. For example... Figure 4 As shown, the focused spot group 102 (including focused spots 102a and 102b) is located within the same preset region 201 of the electrode line. Simultaneously, multiple focused spots are spaced apart to avoid overlap or interleaving, thus preventing over-etching of the same location by different focused spots. Figure 4 As shown, the focused light spots 102a and 102b are spaced apart from each other.

[0061] Typically, the preset region of an electrode line has a certain length. Therefore, a pulsed laser device needs to control multiple laser sub-beams to scan the preset region of the electrode line, so that multiple focused beams etch the same preset region of the electrode line along the scanning direction. During the scanning process, the overall structure formed by multiple focused beams will successively irradiate different positions of the preset region of the electrode line along the scanning direction, thus forming an etching trajectory. Since each focused beam forms an etching hole at each irradiation position, in other words, all the etching holes formed within the preset region of the electrode line can form an etching trajectory. For example, combined with... Figures 3 to 4 As shown, when the pulsed laser device controls the focused spot group 102 to scan along the scanning direction a, the preset area 201 of the electrode line is irradiated 7 times, thus forming a shape as shown in the figure. Figure 6 The etching trajectory 220 shown extends along the scanning direction a. The etching trajectory 220 includes 7 sets of etching hole groups 210. The two etching holes 211 of each set of etching hole groups 210 are formed by each irradiation of the focused spot group 102. Therefore, the two etching holes 211 of each set of etching hole groups 210 correspond perfectly to the positions of each irradiation of the focused spots 102a and 102b.

[0062] As will be understood by those skilled in the art, the pulsed laser device includes a pulsed laser, which controls the focused spot to scan along a preset path (direction a in the figure) through a galvanometer module and a field lens. By controlling the pulse frequency and scanning speed, the aforementioned number of irradiations can be achieved.

[0063] Multiple focused light spots can form etching tracks on the battery surface. The width of the etching tracks can be understood as the etching width, such as... Figure 6 As shown, the etching width w is the width between the lower boundary of the lower etched hole and the upper boundary of the upper etched hole in each group of etched holes. That is, in this application, the etching width is the width of the entire structure formed by multiple focused spots along the vertical scanning direction, ignoring the area difference between the focused spot and its corresponding etched hole. For example... Figure 4 In the etching scheme shown, the etching width w is the width between the lower boundary of the focused spot 102a and the upper boundary of the focused spot 102b.

[0064] In the laser etching process using multiple laser sub-beams in a pulsed laser device, the laser etching effect can be improved and battery performance optimized by rationally setting the arrangement of multiple focused beams. To elaborate:

[0065] Multiple focused beams need to meet the following condition: at least two of the focused beams must be arranged at an acute angle to the scanning direction of the multiple focused beams. For example... Figure 4 As shown, the two focused spots 102a and 102b in the focused spot group 102 are arranged along the dashed line b. Therefore, the dashed line b is their arrangement direction. More specifically, the dashed line b can be defined as the line connecting the centers of the two focused spots 102a and 102b. The dashed line b has an angle t with the scanning direction a, and the angle t is an acute angle, i.e., 0° < angle t < 90°.

[0066] When multiple focused light spots meet the above conditions and etch the same preset area of ​​the electrode line, and based on the one-to-one correspondence between the focused light spots and the etched holes, in each group of etched holes on the etching trajectory, there will also be at least two etched holes whose arrangement direction is at an acute angle to the scanning direction of the multiple focused light spots.

[0067] After laser etching is completed, metal can be filled into each etched hole in the subsequent seeding process and allowed to overflow to form a continuous seed layer. A conductive layer can then be formed on the seed layer through various processes such as electroplating.

[0068] When comparing the laser etching scheme of this application with the aforementioned existing laser etching schemes, it can be concluded that:

[0069] On the one hand, while keeping the number of all etched holes constant, this application can effectively improve processing efficiency when the laser frequency is consistent (e.g., Figures 3 to 6 In the scheme shown, the focused spot group has two focused spots, which only need to be irradiated 7 times, while the existing laser etching scheme requires 14 irradiations. Therefore, this application can improve the etching rate by 100%. When the laser frequency is different, this application can use a low-frequency laser to reduce the cost of the pulsed laser device while maintaining the scanning rate.

[0070] On the other hand, while maintaining the same number of etched holes and the same area of ​​the focused spot as the single spot in the prior art, the same damage area can be maintained. However, the present application can significantly increase the etching width so that when the seed layer is formed by seeding through the etched holes, the seed width can be increased in the vertical scanning direction, that is, the seed area can be increased. This facilitates a larger contact area between the seed layer and the conductive layer, so that the two can form a good contact effect, avoid falling off, effectively reduce the series resistance, and improve the fill factor (FF), thereby improving the photoelectric conversion efficiency.

[0071] On the other hand, while maintaining the same etching width and seed crystal area, the same series resistance can be maintained. However, this application can reduce the area of ​​the focused spot, thereby reducing the area of ​​the damaged region, increasing the P / N area, improving the effective area of ​​photoelectric conversion and the fill factor, thereby achieving the purpose of increasing the photoelectric conversion efficiency.

[0072] In summary, this application can selectively improve aspects such as processing efficiency, processing cost, etching width, seed crystal area, series resistance, fill factor, and photoelectric conversion efficiency by using multiple focused light spots that meet the aforementioned conditions to perform laser etching on a preset area of ​​the same electrode line.

[0073] Furthermore, by using the aforementioned arrangement of at least two focused light spots at an acute angle, the overall length of these two focused light spots in the scanning direction is at least greater than the length of a single focused light spot. This can minimize or even avoid the shortening of the resulting etching trajectory.

[0074] The number of multiple focused light spots can be reasonably selected according to actual needs, for example... Figures 3 to 6 In one scheme, the number of focused light spots is two; for example... Figure 7 or Figure 8 In the scheme shown, the number of focused light spots is three, that is, the focused light spot group 102 includes focused light spots 102a, 102b and 102c.

[0075] When the number of focused spots is three or more, their arrangement can be flexibly chosen, as long as the following conditions are met: the focused spots are spaced apart from each other, and the arrangement direction of at least two focused spots forms an acute angle with the scanning direction. For example, all focused spots can be arranged in a straight line or randomly. Specifically: In one possible implementation, such as Figure 7 As shown, the focused light spots 102a, 102b, and 102c are spaced apart from each other, and the arrangement direction of the focused light spots 102a and 102b forms an acute angle with the scanning direction; in another possible embodiment, as... Figure 8As shown, the focused light spots 102a, 102b and 102c are spaced apart from each other, and the arrangement direction of the focused light spots 102a, 102b and 102c is at an acute angle to the scanning direction.

[0076] The etching width should be within a reasonable range. An excessively wide etching width may be detrimental to the layout of electrode lines on the battery surface. Therefore, in some possible implementations, the etching width can be less than or equal to 0.12 mm. Preferably, the etching width is 0.07 mm to 0.1 mm, or 0.08 mm to 0.1 mm, or 0.04 mm to 0.12 mm.

[0077] Optionally, the number of multiple focused light spots is two, such as... Figures 3 to 6 As shown.

[0078] Optionally, such as Figure 9 As shown, the pulsed laser device includes a scanning module and a pulsed laser module 110 (which may include several pulsed lasers) and a beam splitting module 130 arranged sequentially along the optical path. The laser beam emitted by the pulsed laser module 110 is split into multiple laser sub-beams by the beam splitting module 130. The scanning module is used to modulate the multiple laser sub-beams to control multiple focused spots to scan the battery along a preset area of ​​the same electrode line.

[0079] The aforementioned multiple focused light spots can complete laser etching of a preset area of ​​the same electrode line in a scanning manner. Furthermore, to flexibly meet various processing requirements, the center-to-center distance between any two focused light spots within the multiple focused light spots and the aforementioned included angle t can be adjusted. Specifically:

[0080] In some possible implementations, such as Figure 9 As shown, the pulsed laser device also includes an angle adjustment module 140, which is driven and connected to the beam splitter module 130. Thus, the angle adjustment module 140 can drive the beam splitter module 130 to rotate, thereby adjusting the angle between the arrangement direction of the focused spot and the scanning direction. Therefore, the angle can be correlated with the pulse value of the motor in the angle adjustment module. By providing the servo motor or stepper motor in the angle adjustment module with a pulse value corresponding to the angle, the angle can be adjusted to the corresponding angle.

[0081] In different implementations, the motor in the angle adjustment module can be a hollow motor, in which case its hollow portion can be located in the optical path. Conversely, when the motor in the angle adjustment module is a solid motor, it can be positioned beside the optical path.

[0082] Optionally, the aforementioned included angle t is an acute angle, and an angle range of 30° to 60° is more suitable, such as 30°, 35°, 40°, 45°, 50°, 55° or 60°.

[0083] For example, an included angle t of 30° allows for a suitable etching width. Based on this, when there are two focused light spots, the two etched holes formed on the battery by these focused light spots form an isosceles triangle with respect to any given hole. Figure 6 In the case where the included angle t is 30°, the two etched holes in the leftmost etched hole group and the leftmost etched hole in the etched hole group on the right side of the same etched hole group form an isosceles triangle. This makes the distribution of all etched holes more uniform and the etching width more suitable.

[0084] For example, when there are two focused light spots and the included angle t is 60°, in the etched holes formed by the focused light spots on the battery, any etched hole is distributed in an equilateral triangle with the two etched holes with the smallest distance between them. For example... Figure 6 In the case where the included angle t is 60°, the two etched holes in the leftmost etched hole group and the leftmost etched hole in the etched hole group on the right side of the same etched hole group form an equilateral triangle. This makes the distribution of all etched holes more uniform compared to the scheme where the included angle t is 30°.

[0085] Multiple illuminations are performed during the scanning process. Therefore, when considering all the focused spots corresponding to multiple illuminations, the center-to-center distance between adjacent focused spots in the scanning direction can be divided into intra-group center-to-center distance and inter-group center-to-center distance. Intra-group center-to-center distance can be understood as the center-to-center distance between adjacent focused spots in the same focused spot group 102 in the scanning direction. For example, each focused spot in the same focused spot group 102 has an orthographic projection in the scanning direction. Therefore, intra-group center-to-center distance can also be understood as the center-to-center distance between the orthographic projections of adjacent focused spots in the same focused spot group 102 in the scanning direction. The inter-group center spacing can be understood as the minimum center-to-center distance in the scanning direction between any focused spot in the previous illumination group and any focused spot in the subsequent illumination group during two adjacent illuminations. For example, each focused spot in the previous illumination group has a first orthographic projection in the scanning direction, and each focused spot in the subsequent illumination group also has a second orthographic projection in the scanning direction. Therefore, the inter-group center spacing can also be understood as the minimum center-to-center distance in the scanning direction between the first orthographic projection of any focused spot in the previous illumination group and the second orthographic projection of any focused spot in the subsequent illumination group. For example... Figure 5 The diagram shows the focused light spots formed on the battery in two adjacent irradiations. The focused light spot group 102 on the left was formed in the previous irradiation, and the focused light spot group 102 on the right was formed in the subsequent irradiation. Therefore, the center-to-center distance within the group is e, and the center-to-center distance between groups is f.

[0086] Optionally, the pulsed laser device also includes a spacing adjustment module located in the optical path. The spacing adjustment module can adjust the laser phase of the laser sub-beams emitted from it, thereby changing the emission angle of the laser sub-beams and achieving the purpose of adjusting the center spacing within the group.

[0087] Specifically, the spacing adjustment module may include multiple replaceable beam shaping mirrors disposed in the optical path. Each beam shaping mirror corresponds to a center-to-center spacing within a group. In other words, when it is necessary to adjust the center-to-center spacing within a group, the existing beam shaping mirror in the optical path can be removed first, and then another beam shaping mirror can be replaced in the optical path to change the center-to-center spacing within the group. Alternatively, the spacing adjustment module may also include a spatial beam modulator. Adjusting the electrical signal applied to the spatial beam modulator changes the direction of the liquid crystal within the spatial beam modulator, thereby changing the laser phase. Specifically, each electrical signal can correspond to a center-to-center spacing within a group.

[0088] A beam shaper, positioned in the optical path, can be located between the beam expander and the scanning module. Similarly, a spatial beam modulator can also be located between the beam expander and the scanning module.

[0089] Optionally, the aforementioned inter-group center spacing can be adjusted by controlling the speed of the scanning module and the frequency of the pulsed laser.

[0090] In some possible implementations, the center-to-center spacing within a group is 40 μm to 100 μm, such as 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0091] In some possible implementations, the center-to-center spacing between groups is 40 μm to 100 μm, such as 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0092] In some possible implementations, the intra-group center spacing and the inter-group center spacing can be equal or slightly different, for example, the intra-group center spacing is greater than the inter-group center spacing.

[0093] In some possible implementations, the diameter of the focused spot is 20 μm to 36 μm, such as 20 μm to 25 μm, or 25 μm to 36 μm.

[0094] In some possible implementations, the frequency of the pulsed laser is from 500 kHz to 1000 kHz, such as 500 kHz, 600 kHz, 700 kHz, 800 kHz, 900 kHz, or 1000 kHz.

[0095] In some possible implementations, when the aforementioned pulsed laser frequency, focused spot diameter, intra-group center spacing, inter-group center spacing, etching width, and included angle range are met, the final etched hole can meet the requirements, which facilitates the improvement of subsequent seed crystal quality and thus optimizes the performance of the electrodes in the battery.

[0096] By adjusting the spacing between focused laser spots, the etching trajectory formed by multiple focused laser spots can be minimized or even avoided compared to existing laser etching methods, where the etching trajectory is shorter. Specifically: Figure 2 The etched holes 22 are distributed at single-line intervals along the etching trajectory 21, and the center-to-center distance between two adjacent etched holes 22 is c; while when using the method of this application Figure 7 In the scheme shown, the center-to-center distance between two etched holes 211 in each group of etched holes 210 in the scanning direction a (based on the positional correspondence between the focused spot and the etched hole, equivalent to the aforementioned intra-group center-to-center distance e) can also be kept c, and the center-to-center distance between two etched holes 211 that are close to each other in adjacent etched hole groups 210 in the scanning direction a (equivalent to the aforementioned inter-group center-to-center distance f) can also be kept c. In this way, the length of the etching trajectory formed by the laser etching scheme of this application is equal to that of the etching trajectory formed by the existing laser etching scheme.

[0097] Optionally, the shape of the focused spot in this application is not limited, such as a circular spot, an elliptical spot, a square spot, a near-circular spot, or a near-elliptical spot.

[0098] Optionally, such as Figure 9 As shown, the scanning module includes a galvanometer module 150 and a field mirror located in the optical path. The galvanometer module is located on the light-emitting side of the beam splitter module, and the field mirror is located on the light-emitting side of the galvanometer module. In this way, when multiple laser sub-beams are incident on the galvanometer module 150, the galvanometer module 150 can swing to illuminate different positions of the battery, thereby achieving the aforementioned scanning.

[0099] Optionally, the scanning module may also include a driving module, which is connected to the base station. This allows the driving module to move the base station and the battery on the base station, thereby changing the position of the multiple laser sub-beams irradiating the battery, thus achieving the aforementioned scanning.

[0100] Optionally, the scanning module can also be a driving module, which is connected to the pulsed laser module and the beam splitter module. This allows the driving module to move the pulsed laser module and the beam splitter module, thereby changing the position of the multiple laser sub-beams irradiating the battery, thus achieving the aforementioned scanning.

[0101] Optionally, such as Figure 9As shown, the pulsed laser device may also include a beam expander module 120, which is located between the pulsed laser module 110 and the beam splitter module 130, so that the laser beam emitted from the pulsed laser module 110 is first expanded by the beam expander module 120 and then enters the beam splitter module 130.

[0102] Optionally, multiple etched holes formed on the battery by the same focused light spot are spaced apart, and etched holes formed on the battery by different focused light spots are also spaced apart. For example... Figure 6 As shown, all etched holes are spaced a certain distance apart to avoid over-etching.

[0103] Optionally, as mentioned above, the electrode is an electrode grid line, which can be composed of several electrode lines. Specifically, the several electrode lines may include several main grid lines and / or several fine grid lines. Therefore, the area preset by the main grid lines can be used as the main grid line preset area, and the area preset by the fine grid lines can be used as the fine grid line preset area.

[0104] Alternatively, the focused spot can be a Gaussian spot or a flat-top spot.

[0105] Another aspect of the embodiments of this application provides a laser etching method, such as... Figure 10 As shown, the method includes:

[0106] S10: Multiple focused light spots are formed within a preset area on the same electrode line on the surface of the battery using multiple laser sub-beams, wherein the multiple focused light spots are spaced apart from each other.

[0107] S20: Control multiple focused light spots to scan the battery along a preset area of ​​the same electrode line, wherein the arrangement direction of at least two of the multiple focused light spots is set at an acute angle to the scanning direction of the multiple focused light spots.

[0108] like Figure 3 As shown, multiple laser sub-beams are controlled to propagate towards a battery placed inside the base. Each laser sub-beam that hits the battery surface can form a focused spot on the battery surface, thus multiple laser sub-beams can form multiple focused spots on the battery surface. For example, combining... Figure 3 and Figure 4 As shown, when there are two laser sub-beams 101, the two laser sub-beams 101 form a focused spot group 102 on the surface of the battery, including focused spots 102a and 102b.

[0109] To optimize laser etching results, it is necessary to ensure that all focused spots formed by multiple laser sub-beams are located within a preset area along the same electrode line. For example... Figure 4As shown, the focused spot group 102 (including focused spots 102a and 102b) is located within the same preset region 201 of the electrode line. Simultaneously, multiple focused spots are spaced apart to avoid overlap or interleaving, thus preventing over-etching of the same location by different focused spots. Figure 4 As shown, the focused light spots 102a and 102b are spaced apart from each other.

[0110] Typically, the preset region of an electrode line has a certain length. Therefore, multiple laser sub-beams need to be controlled to scan this region, allowing multiple focused beams to etch the same preset region along the scanning direction. During the scanning process, the combined effect of these multiple focused beams sequentially irradiates different locations within the preset region of the electrode line along the scanning direction, thus forming an etching trajectory. Since each focused beam forms an etching hole at each irradiation location, in other words, all the etching holes formed within the preset region of the electrode line can constitute an etching trajectory. For example, combining... Figures 3 to 4 As shown, when the pulsed laser device controls the focused spot group 102 to scan along the scanning direction a, it irradiates the preset area 201 of the electrode line seven times, thus forming a shape as shown. Figure 6 The etching trajectory 220 shown extends along the scanning direction a. The etching trajectory 220 includes 7 sets of etching hole groups 210. The two etching holes 211 of each set of etching hole groups 210 are formed by each irradiation of the focused spot group 102. Therefore, the two etching holes 211 of each set of etching hole groups 210 correspond perfectly to the positions of each irradiation of the focused spots 102a and 102b.

[0111] As will be understood by those skilled in the art, the pulsed laser device uses a pulsed laser, and the focused spot is controlled to scan along a preset path (direction a in the figure) by a galvanometer and a field mirror. By controlling the pulse frequency and scanning speed, the aforementioned number of irradiations can be achieved.

[0112] Multiple focused light spots can form etching tracks on the battery surface. The width of the etching tracks can be understood as the etching width, which in this application refers to the width of the multiple focused light spots along the vertical scanning direction, for example... Figure 4 In the etching scheme shown, the etching width w is the distance between the lower boundary of the focused spot 102a and the upper boundary of the focused spot 102b, ignoring the area difference between the focused spot and the corresponding etched hole. Figure 6 As shown, the etching width w is also the distance between the lower boundary of the lower etched hole and the upper boundary of the upper etched hole in each group of etched holes.

[0113] In laser etching using multiple laser sub-beams, the etching effect can be improved and battery performance optimized by rationally arranging the multiple focused beams. To elaborate:

[0114] Multiple focused beams need to meet the following condition: at least two of the focused beams must be arranged at an acute angle to the scanning direction of the multiple focused beams. For example... Figure 4 As shown, the two focused spots 102a and 102b in the focused spot group 102 are arranged along the dashed line b. Therefore, the dashed line b is their arrangement direction. More specifically, the dashed line b can be defined as the line connecting the centers of the two focused spots 102a and 102b. The dashed line b has an angle t with the scanning direction a, and the angle t is an acute angle, i.e., 0° < angle t < 90°.

[0115] When multiple focused light spots meet the above conditions and etch the same preset area of ​​the electrode line, and based on the one-to-one correspondence between the focused light spots and the etched holes, in each group of etched holes on the etching trajectory, there will also be at least two etched holes whose arrangement direction is at an acute angle to the scanning direction of the multiple focused light spots.

[0116] After laser etching is completed, metal can be filled into each etched hole in the subsequent seeding process and allowed to overflow to form a continuous seed layer. A conductive layer can then be formed on the seed layer through various processes such as electroplating.

[0117] Based on the comparison between the aforementioned laser etching apparatus and existing laser etching solutions, this application can selectively improve aspects such as processing efficiency, processing cost, etching width, seed crystal area, series resistance, fill factor, and photoelectric conversion efficiency when using multiple focused light spots that meet the aforementioned conditions to perform laser etching on a preset area of ​​the same electrode line.

[0118] Of course, the limitation of the focused spot in the laser etching method of this application can be referred to the description of the aforementioned laser etching device, and therefore has the same or corresponding improvement effect, which will not be repeated here.

[0119] For ease of understanding, some examples will be given below:

[0120] Example 1

[0121] The beam splitter module divides the laser beam into two sub-beams. The two sub-beams pass through the galvanometer module, and the laser frequency, focused spot diameter, center-to-center distance, angle, and scanning speed of the galvanometer module are set to scan the passivation layer of the preset area of ​​the BC battery electrode line to complete the etching process.

[0122] The pulsed laser frequency is 1000kHz, the galvanometer module processing speed is 128m / s, the focused spot size is 32-34μm, the center-to-center spacing within and between groups is 73.9μm, the included angle t is adjusted to 30°, the CT (processing time) is 0.92s, and the production capacity is increased by 97.8% compared to the existing Gaussian single-beam single-spot solution (existing laser etching solution). The photoelectric conversion efficiency of the produced BC solar cells is 26.4-26.6%, which is 0.1-0.2% higher than that of the Gaussian single-beam single-spot solution.

[0123] Of course, the beam splitter module can adjust the included angle in real time through the angle adjustment module control.

[0124] Example 2

[0125] The pulsed laser frequency is 500kHz, the galvanometer module processing speed is 64m / s, the focused spot diameter is 32-34μm, the center-to-center spacing within and between groups is 73.9μm, the included angle t is adjusted to 60°, and the CT (processing time) is 1.82s. The production capacity is the same as that of a Gaussian single-beam single-spot laser, but the pulsed laser frequency is reduced from 1000K to 500K, which can reduce the cost of production equipment. The photoelectric conversion efficiency of the produced BC solar cells is 26.4-26.6%, which is 0.1-0.2% higher than that of a Gaussian single-beam single-spot laser.

[0126] Example 3

[0127] The pulsed laser frequency is 750kHz, the galvanometer module processing speed is 96m / s, the focused spot diameter is 32-34μm, the center-to-center spacing within and between groups is 73.9μm, the included angle t is 30°, and the processing time (CT) is 1.23s. The throughput is 47.9% higher than that of Gaussian single-beam spot. At the same time, the pulsed laser frequency is reduced from 1000K to 750K, which can reduce the cost of production equipment. The photoelectric conversion efficiency of the produced BC solar cells is 26.4-26.6%, which is 0.1-0.2% higher than that of Gaussian single-beam spot.

[0128] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A laser etching apparatus, characterized in that, Includes a pulsed laser device and a base for supporting the battery; The pulsed laser device is used to emit multiple laser sub-beams toward the battery. The surface of the battery has at least one electrode line preset area. After the multiple laser sub-beams are emitted, they form multiple focused light spots located in the same preset area of ​​the electrode line. The multiple focused light spots are spaced apart from each other. The pulsed laser device is used to control the plurality of focused light spots to scan the battery along the same electrode line preset area, and the arrangement direction of at least two of the plurality of focused light spots is set at an acute angle to the scanning direction of the plurality of focused light spots.

2. The laser etching apparatus as described in claim 1, characterized in that, The multiple focused light spots are arranged in a straight line.

3. The laser etching apparatus as described in claim 1, characterized in that, The width of the plurality of focused light spots along the direction perpendicular to the scanning direction is the etching width, and the etching width is less than or equal to 0.12 mm.

4. The laser etching apparatus as described in claim 3, characterized in that, The etching width is 0.07 mm to 0.1 mm, or the etching width is 0.08 mm to 0.1 mm, or the etching width is 0.04 mm to 0.12 mm.

5. The laser etching apparatus as described in claim 1, characterized in that, The number of the plurality of focused light spots is two, and / or the acute angle is 30° to 60°.

6. The laser etching apparatus as described in claim 5, characterized in that, When the number of the plurality of focused light spots is two and the acute angle is 30°, the focused light spots are distributed in an isosceles triangle with the two etched holes with the smallest distance between them in the etched holes formed on the battery. When the number of the plurality of focused light spots is two and the acute angle is 60°, the focused light spots are distributed in an equilateral triangle with the two etched holes with the smallest distance between them in the etched holes formed on the battery.

7. The laser etching apparatus as described in claim 1, characterized in that, Among the plurality of focused light spots, the center-to-center distance between adjacent focused light spots in the scanning direction is the center-to-center distance within the group; In two adjacent irradiations, the minimum center-to-center distance between any of the focused light spots in the previous irradiation and any of the focused light spots in the subsequent irradiation in the scanning direction is the inter-group center-to-center distance. The center-to-center distance within a group is greater than or equal to the center-to-center distance between groups.

8. The laser etching apparatus according to any one of claims 1 to 7, characterized in that, The diameter of the focused spot is 20 μm to 36 μm; And / or, in the plurality of focused spots, the center-to-center distance between adjacent focused spots in the scanning direction is 40 μm to 100 μm; And / or, in two adjacent irradiations, the minimum center-to-center distance between any of the focused spots in the previous irradiation and any of the focused spots in the subsequent irradiation in the scanning direction is 40 μm to 100 μm.

9. The laser etching apparatus according to any one of claims 1 to 7, characterized in that, The frequency of the pulsed laser device is 500kHz to 1000kHz.

10. The laser etching apparatus according to any one of claims 1 to 7, characterized in that, The pulsed laser device includes a pulsed laser module, a beam splitting module, and a scanning module arranged sequentially along the optical path. The laser beam emitted by the pulsed laser module is split into multiple laser sub-beams by the beam splitting module. The scanning module is used to modulate the multiple laser sub-beams to control the multiple focused light spots to scan the battery along the same preset area of ​​the electrode line.

11. The laser etching apparatus as described in claim 10, characterized in that, The pulsed laser device further includes an angle adjustment module, which is driven and connected to the beam splitting module. The angle adjustment module drives the beam splitting module to rotate in order to adjust the angle between the arrangement direction of at least two of the focused light spots and the scanning direction of the plurality of focused light spots.

12. The laser etching apparatus as described in claim 10, characterized in that, The pulsed laser device also includes multiple beam shaping mirrors. The laser beam has different laser phases after being modulated by different beam shaping mirrors. The multiple beam shaping mirrors are used to replace each other in the optical path. Alternatively, the pulsed laser device may further include a spatial beam modulator located in the optical path.

13. The laser etching apparatus as described in claim 10, characterized in that, The scanning module includes a galvanometer module and a field lens located in the optical path, wherein the galvanometer module is located on the light-emitting side of the beam splitter module, and the field lens is located on the light-emitting side of the galvanometer module; Alternatively, the scanning module may include a driving module, which is driven and connected to the base station; or, the driving module may be driven and connected to the pulsed laser module and the beam splitter module.

14. The laser etching apparatus according to any one of claims 1 to 7, characterized in that, Multiple etched holes formed on the battery by the same focused light spot are spaced apart from each other, and etched holes formed on the battery by different focused light spots are spaced apart from each other.

15. The laser etching apparatus according to any one of claims 1 to 7, characterized in that, The preset area of ​​the electrode line is the preset area of ​​the fine grid line.

16. A laser etching method, characterized in that, The method includes: Multiple focused light spots are formed within a preset area on the same electrode line on the surface of the battery using multiple laser sub-beams, wherein the multiple focused light spots are spaced apart from each other; The plurality of focused light spots are controlled to scan the battery along a preset area of ​​the same electrode line, wherein at least two of the plurality of focused light spots are arranged at an acute angle to the scanning direction of the plurality of focused light spots.

Images