Dynamic focusing laser cutting method and device

Abstract

The present invention provides a dynamic focusing laser cutting method and device, which uses a laser to adjust the divergence angle of the laser, or adjust the relative distance between the surface of the product to be processed and the laser processing module, so that after the laser is focused, a first light spot or a second light spot is formed on the surface of the product to be processed, and the first light spot is used to scan at least two points on the predetermined cutting line to form an induced cutting groove; the second light spot is used to scan along the predetermined cutting line to form thermal stress, so that the product to be processed is broken along the predetermined cutting line; the predetermined cutting line is the line where the product to be processed is to be cut and separated, and the size of the first light spot is smaller than the second light spot. The present invention uses the first light spot and the second light spot formed by dynamic focusing of the same laser to scan, so that the scanning trajectories of the two can be completely consistent with the predetermined cutting line, so that the alignment accuracy of the induced cutting groove and the thermal stress cutting path is excellent, avoiding cutting offset and ensuring the cutting effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser cutting of sheet materials, and in particular relates to a dynamic focusing laser cutting method and device. Background Art

[0002] The existing photovoltaic cell cutting technology can use the thermal cutting method, that is, the laser is focused to a spot of 20~50μm, and the surface of the cell is repeatedly scratched along the cutting line. After a certain depth of molten groove is formed on the cell, a breaking force is applied externally to separate the cell. This cutting method repeatedly scratches with a focused spot, which will cause cutting damage (microcracks) on the cut section and a large heat affected zone (HAZ) on the cell surface, which has a great impact on the electrical performance of the cut cell.

[0003] In order to reduce the damage of laser to photovoltaic cells, a non-destructive cutting method has been developed. The laser is induced to draw an induced cutting groove of a certain length at a specific position of the predetermined cutting line. The stress laser is irradiated on the induced cutting groove and moves along the predetermined cutting line. A local temperature gradient is formed on the irradiated part, and cracks are generated and extended along the induced cutting groove of the cell, thus achieving non-destructive cutting of the cell.

[0004] The applicant found in the research that the non-destructive cutting technology can be processed by using two lasers with different focusing heads: the first focusing head focuses the induction laser to carve an induction groove on the surface of the cell; then the second focusing head focuses the stress laser and makes its motion trajectory coincide with the induction groove and moves along the predetermined cutting line. The double focusing head for non-destructive cutting has low processing efficiency and the problem of misalignment between the induction laser and the stress laser, which affects the cutting effect. Summary of the invention

[0005] The technical problem to be solved by the present invention is: to provide a dynamic focusing laser cutting method and device, which uses the same laser to perform dynamic focusing processing and naturally achieves alignment, thereby avoiding the problems of inaccurate or difficult alignment of one induced laser beam and another stress laser beam in the prior art, and improving the cutting effect.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a dynamic focusing laser cutting method, using a laser,

[0007] Adjust the divergence angle of the laser, or adjust the relative distance between the surface of the product to be processed and the laser processing module, so that the laser is focused to form a first light spot on the surface of the product to be processed, and use the first light spot to scan at least two points on the predetermined cutting line to form an induced cutting groove;

[0008] Adjust the divergence angle of the laser, or adjust the relative distance between the surface of the product to be processed and the laser processing module, so that after the laser is focused, a second light spot is formed on the surface of the product to be processed, and the second light spot is used to scan along the predetermined cutting line to form thermal stress, so that the product to be processed is broken along the predetermined cutting line;

[0009] The predetermined cutting line is a line where the product to be processed is to be cut and separated, and the size of the first light spot is smaller than that of the second light spot.

[0010] According to the above method, the laser is a laser that has undergone flat-top beam shaping, the first light spot is the laser focused to become the minimum focused light spot with a diffraction-limited size; and the second light spot is a flat-top light spot.

[0011] According to the above method, the divergence angle of the laser is adjusted by dynamic focusing using a 3D galvanometer.

[0012] According to the above method, the laser scans once along the predetermined cutting line and is continuously turned on, wherein a first light spot is used at the induced cutting groove, and a second light spot is used at other positions of the predetermined cutting line, and the second light spot at least partially covers the induced cutting groove on the cutting path.

[0013] According to the above method, the laser scans twice along the predetermined cutting line; wherein, the first time, the first light spot is used to turn on the light at the induced cutting groove, and the light is turned off at other positions of the predetermined cutting line; the second time, the second light spot is used to turn on the light along the predetermined cutting line.

[0014] According to the above method, the relative distance between the surface of the product to be processed and the laser processing module is adjusted by moving the laser processing module up and down, or by moving the workbench carrying the product to be processed up and down.

[0015] According to the above method, the number of the induced cutting grooves is two, which are respectively located at the beginning and the end of the predetermined cutting line.

[0016] According to the above method, the width of the first light spot is 20-50 μm; the width of the second light spot is 100-1000 μm, and the length of the second light spot is 1-5 times of the width of the second light spot.

[0017] A dynamic focusing laser cutting device comprises a laser generating device, a laser processing module, a workbench and a control unit; wherein the laser emitted by the laser generating device is sorted by the laser processing module and then irradiated onto a product to be processed on the workbench, and the control unit is used to adjust the divergence angle of the laser or the relative distance between the workbench and the laser processing module according to the dynamic focusing laser cutting method, and control the laser processing module to perform laser scanning relative to the workbench.

[0018] According to the above device, the laser processing module includes a 3D galvanometer, which includes a 3D module and a 2D galvanometer; the control unit adjusts the divergence angle of the laser by adjusting the dynamic focus of the 3D module, and performs laser scanning through the 2D galvanometer.

[0019] According to the above device, the laser processing module includes a diffraction optical device for flattening the laser.

[0020] According to the above device, the device also includes a motion device for driving the workbench or the laser processing module to move up and down. When the motion device is controlled by the control unit to drive the workbench or the laser processing module to move up and down, the laser processing module and the workbench are moved away from or close to each other, and the laser forms a first light spot or a second light spot on the surface of the product to be processed.

[0021] The motion device is also used to drive the workbench to move along the predetermined cutting line under the control of the control unit, thereby realizing the scanning of the first light spot and the second light spot on the predetermined cutting line.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention uses the first light spot and the second light spot formed by dynamic focusing of the same laser for scanning, so that the scanning trajectories of the two can be completely consistent with the predetermined cutting line, thereby achieving excellent alignment accuracy of the induced cutting groove and the thermal stress cutting path, avoiding cutting deviation and ensuring the cutting effect.

[0024] 2. The use of a 3D galvanometer can directly form the required first light spot and second light spot through the dynamic focusing of the galvanometer, which is convenient and quick; further, on this basis, the first light spot is adjusted at the induced cutting groove, and the second light spot is adjusted at other positions of the predetermined cutting line. Only one scan is required to complete lossless cutting, and there is no need to scan back and forth. The advantage of this is that the product to be processed can be transported in an assembly line manner, and the effect of lossless cutting can be achieved by controlling the focusing time of the 3D galvanometer in one scan. The automated design is simple, efficient, and reliable.

[0025] 3. The purpose can also be achieved by adjusting the relative distance between the surface of the product to be processed and the laser processing module to adjust the laser spot on the surface of the product to be processed, which can reduce the cost of the galvanometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural diagram of embodiment 1 of the present invention.

[0027] Figure 2 FIG. 1 is a schematic diagram of a light spot path according to Embodiment 1 of the present invention.

[0028] Figure 3Schematic diagram of the light spot size of the first embodiment of the present invention, wherein (a) is the first light spot and (b) is the second light spot.

[0029] Figure 4 This is a cutting effect diagram of the first embodiment of the present invention.

[0030] Figure 5 This is a cutting effect diagram of the prior art.

[0031] Figure 6 This is a schematic diagram of the structure of the third embodiment of the present invention.

[0032] Figure 7 This is a structural diagram of embodiment 4 of the present invention.

[0033] In the figure: 1-laser, 2-beam expander, 3-flat top light shaper, 4-3D module, 5-2D galvanometer, 5'-2D galvanometer second position, 6-field lens, 6'-field lens second position, 7-first focused laser, 7'-second focused laser, 7''-first focused laser second position, 8-workbench, 8'-workbench second position, 9-sheet material, 9'-sheet material second position, 10-first light spot, 11-predetermined cutting line, 12-induced cutting groove, 13-second light spot. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific examples and drawings.

[0035] The present invention provides a dynamic focusing laser cutting method and device, which uses a laser, preferably a laser that has undergone flat-top beam shaping, and adjusts the working distance of the laser so that a first light spot is formed on the surface of the product to be processed after the first laser focusing, and the first light spot is used to scan at least two points on the predetermined cutting line to form an induced cutting groove; the working distance of the laser is adjusted so that a second light spot is formed on the surface of the product to be processed after the second laser focusing, and the second light spot is used to scan along the predetermined cutting line to form thermal stress, so that the product to be processed is broken along the predetermined cutting line; wherein the predetermined cutting line is a line where the product to be processed is to be cut and separated, and the size of the first light spot is smaller than the second light spot. The light spot is a light spot formed by focusing the laser generated by the laser on the battery cell. The induced cutting groove is a groove cut by a laser or the like on the predetermined cutting line, which is one or multiple grooves arranged at intervals.

[0036] The laser working distance adjustment mentioned above refers to adjusting the laser divergence angle, or adjusting the distance between the surface of the product to be processed and the laser processing module, so as to realize the processing of the material with different light spots. When not undergoing flat-top beam shaping, by adjusting the laser divergence angle (or at different working distances), the light spot will present a focused and defocused state, thereby obtaining light spots of different sizes; when undergoing flat-top beam shaping, by adjusting the laser divergence angle (or at different working distances), the light spot will generally present a process of a flat-top light spot, gradually focusing, focusing to a diffraction-limited size, and gradually diverging (depending on the different phase adjustments of the diffraction optical device, it may also present a process of a diffraction-limited size, gradual divergence, a flat-top light spot, and continued divergence), thereby realizing the formation of the first light spot and the second light spot.

[0037] Embodiment 1:

[0038] This embodiment 1 provides a dynamic focusing laser cutting method, such as Figures 1 to 3 As shown, when completing one cutting, only one laser generating device (in this embodiment, a laser 1) is needed. The emitted laser passes through a beam expander 2, is shaped into a flat top light by a flat top light shaper 3, and then passes through a single 3D galvanometer (including a 3D module 4 and a 2D galvanometer 5 connected in sequence) and a field lens 6 for focusing the laser beam, forming a first focused laser 7 that hits the surface of the product to be processed (i.e., a sheet material 9), forming a first light spot 10. The first light spot 10 is used to scan along a predetermined cutting line 11 in a first direction through a 2D galvanometer. When it reaches The light is turned on when the predetermined induced cutting groove 12 position is reached, and the light is turned off at other positions, thereby forming the induced cutting groove 12. Preferably, there are two induced cutting grooves 12, which are arranged at the beginning and end of the predetermined cutting line 11. The laser divergence angle is adjusted by dynamic focusing of the 3D module to form a second focused laser 7', and a second light spot 13 is formed on the surface of the sheet material 9. The second light spot 13 is scanned along the predetermined cutting line 11 through a 2D galvanometer in the first direction or in a second direction opposite to the first direction, thereby forming thermal stress, so that the sheet material 9 breaks along the predetermined cutting line 11.

[0039] In this embodiment, there is only one laser generating device and galvanometer; the divergence angle of the laser is dynamically adjustable; a control unit is used to adjust the divergence angle of the laser according to the above-mentioned dynamic focusing laser cutting method. The sheet material 9 is set on the workbench 8, and the workbench 8 is preferably a negative pressure adsorption workbench, which is used to adsorb the component to be processed thereon, so that the processing is more stable.

[0040] The wavelength of the laser is a monochromatic laser of 300-1500 Å, preferably 355, 532 or 1064 Å.

[0041] After the shaped laser beam is focused, a flat-top spot will appear at the corresponding position. The laser divergence angle is adjusted by using a dynamic focusing system, or the distance between the workpiece to be processed and the laser processing module is gradually adjusted. The flat-top spot will gradually continue to focus to become a minimum focused spot with a diffraction-limited size. In this embodiment, the first light spot 10 is the minimum focused spot, or it can be a spot near the minimum focused spot, as long as its spot size and energy can meet the requirements of the induced cutting groove 12; the second light spot 13 is a flat-top spot, or it can be a spot near the flat-top spot.

[0042] Furthermore, the width of the first light spot 10 is the width of the induced cutting groove 12; the width of the second light spot 13 is greater than the width of the induced cutting groove 12. The flat-top beam shaper 3 shapes the flat-top light spot into an elongated light spot, and its length direction is in the same direction as the predetermined cutting line direction. More specifically, as an application in the field of silicon wafer cutting technology, the width of the first light spot 10 irradiated on the surface of the product to be processed is 20-50 μm; the width of the second light spot 13 irradiated on the surface of the product to be processed is 100-1000 μm, and the length of the second light spot 13 is 1-5 times the width.

[0043] Figure 4 This is a cutting effect diagram of the first embodiment of the present invention. Figure 5 This is a cutting effect diagram of the prior art (in the first station, the same light spot as the first light spot is used to form an induction groove, and after alignment, the same light spot as the second light spot is used at the second station for thermal cracking). Figure 4 and Figure 5 By comparison, it is found that since the first light spot 10 and the second light spot 13 are formed by dynamic focusing of the same laser beam, their scanning trajectories can be completely consistent with the predetermined cutting line, so that the alignment accuracy of the induced cutting groove and the thermal stress cutting path is excellent, avoiding cutting deviation and ensuring the cutting effect.

[0044] Through dynamic control, a larger spot energy is used when processing the induced cutting groove 12, so that the processing effect of the induced cutting groove 12 is good. When processing the stress groove, uniform thermal stress release is guaranteed, thereby improving the process effect.

[0045] The flat-top light shaper 3 in this embodiment is a diffractive optical device.

[0046] Embodiment 2:

[0047] This embodiment is a variation of the first embodiment, in which the laser scans once along the predetermined cutting line 11, and during the entire scanning process, the laser is controlled to be turned on all the time, wherein a first light spot 10 is used at the induced cutting groove 12, and a second light spot 13 is used at other positions of the predetermined cutting line 11.

[0048] Specifically, during processing, the laser scanning path and focusing time are controlled by the 3D galvanometer. During one scanning process, the first light spot 10 is focused at the induced cutting groove 12, and the second light spot 13 is focused at other positions of the predetermined cutting line 11. In this processing mode, the second light spot at least partially covers the induced cutting groove 12 on the cutting path.

[0049] The advantage of this setting is that the laser can complete the non-destructive cutting process after one scan. (The first light spot 10 completes the processing of the induced cutting groove 12, and the second light spot 13, which is larger than the first light spot, will also cover or at least partially cover the induced cutting groove 12 on the cutting path). It only needs to control the scanning path and focusing time of the 3D galvanometer to achieve the effect of non-destructive cutting in one scan. The automated design is simple, efficient and reliable.

[0050] Embodiment three:

[0051] This embodiment is a variation of the first or second embodiment, and its basic principle and structure are the same as those of the first or second embodiment, except that the working distance of the laser in this embodiment is adjusted by adjusting the distance between the product to be processed and the galvanometer while keeping the laser divergence angle unchanged. Figure 6 As shown, other structures remain unchanged, and the galvanometer can be a low-cost 2D galvanometer 5, and a motion device is provided to drive the 2D galvanometer 5 to move up and down. When the 2D galvanometer 5 and the field lens 6 are at a higher position, the first focused laser 7 forms a first light spot 10 on the sheet material 9; when the 2D galvanometer 5 and the field lens 6 move to the 2D galvanometer second position 5' and the field lens second position 6', the first focused laser 7 does not refocus, but moves to the first focused laser second position 7'', and a second light spot 13 is formed on the sheet material 9.

[0052] The motion device may be a linear module that moves up and down and is arranged on the 2D galvanometer 5 , such as a linear motor or a hydraulic cylinder.

[0053] Embodiment 4:

[0054] The principle and structure of this embodiment are basically the same as those of the third embodiment, and the difference is that the motion device is set as a three-dimensional motion module, the 2D galvanometer 5 is eliminated, and the motion device can drive the laser processing module to scan along the predetermined cutting line 11 in addition to moving up and down. During processing, the three-dimensional motion module drives the laser processing module to scan along the predetermined cutting line 11 on the one hand, and on the other hand, when the light spot needs to be switched, it moves up and down to achieve the light spot switching.

[0055] Embodiment five:

[0056] This embodiment is a variation of the first or second embodiment, and its basic principle and structure are the same as those of the first embodiment, except that the working distance of the laser in this embodiment is adjusted by adjusting the distance between the product to be processed and the galvanometer while keeping the laser divergence angle unchanged. Figure 7 As shown, other structures remain unchanged, and the galvanometer can adopt a low-cost 2D galvanometer 5, and a motion device is provided to drive the workbench 8 to move up and down.

[0057] When the workbench 8 and the sheet material 9 thereon are in a lower position, the first focused laser 7 forms a first light spot 10 on the sheet material 9; when the workbench 8 and the sheet material 9 thereon move to the workbench second position 8' and the sheet material second position 9', the first focused laser 7 is not refocused, and a second light spot 13 is formed on the sheet material.

[0058] The motion device may be a linear module that moves up and down and is arranged on the workbench 8, such as a linear motor or a hydraulic cylinder.

[0059] Embodiment six:

[0060] The principle and structure of this embodiment are basically the same as those of the fifth embodiment, with the difference being that the 2D galvanometer is eliminated, and the motion device is configured as a three-dimensional motion module, which can realize the movement of the workbench 8 along a predetermined cutting line in addition to moving up and down. During processing, the three-dimensional motion module, on the one hand, drives the workbench 8 to move along the predetermined cutting line 11 to realize laser scanning, and on the other hand, when it is necessary to switch the light spot, the workbench 8 moves up and down to realize the light spot switching.

[0061] Those skilled in the art know that, in addition to the above-mentioned configuration, laser dynamic focusing and scanning can be achieved through a combination of one or more methods such as galvanometer, workbench movement, and laser processing module movement.

[0062] Preferably, the sheet material in the present application is a solar cell.

[0063] The above embodiments are only used to illustrate the design ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims

1. A dynamic focusing laser cutting method, characterized in that: Using a laser, A 3D galvanometer is used to adjust the divergence angle of the laser through dynamic focusing, so that a first light spot is formed on the surface of the product to be processed after the laser is focused, and the first light spot is used to scan at least two points on the predetermined cutting line to form an induced cutting groove; A 3D galvanometer is used to adjust the divergence angle of the laser through dynamic focusing, so that a second light spot is formed on the surface of the product to be processed after the laser is focused, and the second light spot is used to scan along a predetermined cutting line to form thermal stress, so that the product to be processed is broken along the predetermined cutting line; Wherein, the predetermined cutting line is a line where the product to be processed is to be cut and separated, and the size of the first light spot is smaller than the second light spot; The laser scans once along the predetermined cutting line and is continuously turned on, wherein a first light spot is used at the induced cutting groove, and a second light spot is used at other positions of the predetermined cutting line, and the second light spot at least partially covers the induced cutting groove on the cutting path.

2. The method according to claim 1, characterized in that: The laser is a laser that has undergone flat-top beam shaping, the first light spot is the laser focused to become a minimum focused light spot with a diffraction-limited size; and the second light spot is a flat-top light spot.

3. The method according to claim 1, characterized in that: The number of the induced cutting grooves is two, which are respectively located at the beginning and the end of the predetermined cutting line.

4. The method according to claim 1, characterized in that: The width of the first light spot is 20-50 μm; the width of the second light spot is 100-1000 μm, and the length of the second light spot is 1-5 times of the width of the second light spot.

5. A dynamic focusing laser cutting device, comprising a laser generating device, a laser processing module, a workbench and a control unit; wherein: The laser emitted by the laser generating device is sorted by the laser processing module and then irradiated onto the product to be processed on the workbench, and is characterized in that: the control unit is used to adjust the divergence angle of the laser according to the dynamic focusing laser cutting method according to claim 1, and control the laser processing module to perform laser scanning relative to the workbench.

6. The device according to claim 5, characterized in that: The laser processing module includes a 3D galvanometer, which includes a 3D module and a 2D galvanometer; the control unit adjusts the divergence angle of the laser by adjusting the dynamic focus of the 3D module, and performs laser scanning through the 2D galvanometer.

7. The device according to claim 5, characterized in that: The laser processing module includes a diffraction optical device for flattening the laser.

8. The device according to claim 5, characterized in that: The device also includes a motion device for driving the workbench or the laser processing module to move up and down. When the motion device is controlled by the control unit to drive the workbench or the laser processing module to move up and down, the laser processing module and the workbench are moved away from or close to each other, and the laser forms a first light spot or a second light spot on the surface of the product to be processed. The laser processing module of the device also includes a 2D galvanometer, and the control unit controls the 2D galvanometer to perform laser scanning.

9. The device according to claim 5, characterized in that: The device also includes a motion device, It is used to drive the workbench to move along the predetermined cutting line under the control of the control unit, so as to realize the scanning of the first light spot and the second light spot on the predetermined cutting line.

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