Laser welding device and laser welding method

Abstract

The invention relates to a laser welding device and a laser welding method. The laser welding device comprises a first carrying table, a second carrying table arranged above the first carrying table, a pressing assembly and a laser welding assembly, the pressing assembly and the laser welding assembly are arranged on the second carrying table and close to one side of the first carrying table, and the face, close to the second carrying table, of the first carrying table is a bearing face which is configured to bear a back plate and a wafer. A to-be-welded chip on the wafer is aligned with a corresponding bonding pad on the back plate; the pressing assembly is configured to apply pressure to the wafer from one side of the wafer, so that a chip electrode on the wafer is in contact with a bonding pad on the back plate, and after the pressing assembly applies pressure to the wafer to enable the chip electrode on the wafer to be in contact with the bonding pad on the back plate, the chip electrode on the wafer is pressed to be in contact with the bonding pad on the back plate. And the chip electrode and the bonding pad which are in contact are welded through the laser welding assembly, so that the problem of poor welding caused by warping between the wafer and the back plate is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor production and manufacturing, and in particular to a laser welding device and a laser welding method. Background Art

[0002] As a new generation of display technology, Micro-LED has higher brightness, better luminous efficiency, low power consumption and long life compared to LCD and OLED technologies. In the process of Micro-LED preparation, mass welding is an important link to improve the efficiency of mass transfer. During mass welding, the chip is fixed and grown on the wafer. The wafer and the backplane are aligned on the download table of the laser welding machine. The laser welding machine presses the wafer and the backplane together and fixes them on the download table through a buckle ring. Since there is a layer of light-emitting chip between the wafer and the backplane, and the buckle ring is in the process of pressing the wafer and the backplane, if there is no support for the light-emitting chip under the pressing part of the buckle ring or it only presses the corner of the light-emitting chip, it will cause the wafer to bend, resulting in a gap between the chip electrode on the wafer and the pad of the backplane, such as Figure 1 As shown, since there is a gap between the chip electrode and the pad and no effective contact is formed, it is easy to cause a cold solder joint between the chip electrode and the pad during the laser welding process, which seriously affects the welding yield.

[0003] Therefore, how to solve the problem of poor welding caused by warping between the wafer and the backplane during laser welding is an issue that needs to be solved urgently. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned related technologies, the purpose of the present application is to provide a laser welding device and a laser welding method, aiming to solve the problem of poor welding caused by warping between the wafer and the backplane in the existing laser welding process.

[0005] A laser welding device comprises: a first carrier, a second carrier arranged above the first carrier, and a laser welding assembly and a pressing assembly arranged on the second carrier and close to one side of the first carrier, wherein the laser welding assembly and the pressing assembly are arranged adjacent to each other;

[0006] A side of the first stage close to the second stage is a carrying surface, and the carrying surface is configured to carry a back plate and a wafer, and the back plate and the wafer are sequentially stacked on the carrying surface;

[0007] The pressing assembly is configured to apply pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer contact with the pads on the backplane;

[0008] The laser welding assembly is configured to weld the contacted chip electrodes and pads.

[0009] The above-mentioned laser welding device includes a pressing component and a laser welding component. The pressing component is configured to apply pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer contact the pads on the backplane. After the pressing component applies pressure to the wafer to make the chip electrodes on the wafer contact the pads on the backplane, the contacting chip electrodes and pads are welded by the laser welding component, thereby solving the problem of poor welding between the wafer and the backplane caused by warping.

[0010] Optionally, it further comprises an annular fixing assembly disposed between the first carrier and the second carrier, wherein the annular fixing assembly is configured to apply pressure to the periphery of the wafer so that the wafer is aligned and fixed with the back plate;

[0011] The press assembly is configured to apply pressure to the wafer within the annular fixture assembly.

[0012] The above-mentioned laser welding device arranges an annular fixing component between the first carrier and the second carrier, and fixes the wafer and the back plate in position through the annular fixing component. At the same time, the pressing component is configured to apply pressure to the wafer located in the annular fixing component so that the chip electrodes in the area and the adjacent area on the wafer contact with the pads on the back plate, so that the pressing component can set different pressing pressures according to the warping degree of different areas of the wafer to achieve better welding effect.

[0013] Optionally, the pressing assembly includes a pressing portion and a connecting portion, the pressing portion is connected to the second carrier through the connecting portion, and the pressing portion can roll along a direction perpendicular to an extending direction of the connecting portion.

[0014] In the above-mentioned laser welding device, the pressing assembly includes a pressing part and a connecting part. When the pressing assembly and the first carrier move horizontally relative to each other, the pressing part can be adjusted to above the current area to be welded or the adjacent area to be welded by rolling without lifting the pressing part, thereby improving the welding efficiency.

[0015] Based on the same inventive concept, the present application also provides a laser welding method, comprising:

[0016] Providing a laser welding device as described in any one of the present applications;

[0017] The back plate and the wafer are sequentially stacked on the carrying surface of the first carrier;

[0018] Placing the pressing assembly above the wafer and applying pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer are in contact with the pads on the backplane;

[0019] The laser welding assembly is controlled to weld the chip electrodes and the pads that are in contact.

[0020] The above-mentioned laser welding method is applied in a laser welding device provided in the present application, wherein a pressing assembly is placed above a wafer, and the pressing assembly applies pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer contact with the pads on the backplane, and then the contacting chip electrodes and the pads are welded by a laser welding assembly, thereby solving the problem of poor welding between the wafer and the backplane caused by warping. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a conventional laser welding device provided by an embodiment of the present invention showing warping of a wafer and a back plate after the unloading platform fixes the wafer and the back plate;

[0022] Figure 2 A schematic structural diagram of a laser welding device provided in an embodiment of the present invention;

[0023] Figure 3 A schematic structural diagram of another laser welding device provided by an embodiment of the present invention;

[0024] Figure 4 A schematic structural diagram of another laser welding device provided by an embodiment of the present invention;

[0025] Figure 5 A top view of a first carrier of a laser welding device provided in another optional embodiment of the present invention;

[0026] Figure 6 A schematic structural diagram of a laser welding device provided in another optional embodiment of the present invention;

[0027] Figure 7 A schematic structural diagram of another laser welding device provided for another optional embodiment of the present invention;

[0028] Figure 8 A schematic structural diagram of another laser welding device provided for another optional embodiment of the present invention;

[0029] Fig. 9 A schematic structural diagram of another laser welding device provided for another optional embodiment of the present invention;

[0030] Fig.10 A schematic structural diagram of another laser welding device provided for another optional embodiment of the present invention;

[0031] Fig.11 For this embodiment Fig. 9A schematic diagram of the structure of a left view of a laser welding device is provided;

[0032] Fig.12 A schematic structural diagram of another laser welding device provided for another optional embodiment of the present invention;

[0033] Fig.13 A schematic structural diagram of another laser welding device provided for another optional embodiment of the present invention;

[0034] Fig.14 A partially enlarged structural schematic diagram of a laser welding device provided in another optional embodiment of the present invention;

[0035] Fig.15 A schematic flow chart of a laser welding method provided for yet another optional embodiment of the present invention.

[0036] Description of reference numerals:

[0037] 100-first stage; 200-second stage; 300-laser welding assembly; 400-pressing assembly; 500-back plate; 600-wafer; 700-annular fixing assembly; 101-first driving assembly; 201-second driving assembly; 800-third driving assembly; 701-fixing buckle; 702-telescopic connecting rod; 401-roller; 402-first connecting rod; 403-second connecting rod; 404-first bearing; 405-second bearing; 406-connecting part; 407-pressing part; 408-fixed shaft; 900-pressure adjustment assembly; L-first preset distance. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly and comprehensively understood.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0040] In the existing Micro-LED preparation process, the chip is fixedly grown on the wafer, and the wafer and the backplane are aligned on the unloading table of the laser welding machine. The laser welding machine presses the wafer and the backplane together and fixes them on the unloading table through a buckle ring. Since there is a layer of light-emitting chip between the wafer and the backplane, if there is no support of the light-emitting chip under the buckle ring during the process of pressing the wafer and the backplane, or if the buckle ring only presses the corner of the light-emitting chip, the wafer will bend, resulting in a gap between the chip electrode on the wafer and the pad of the backplane, such as Figure 1 As shown, since there is a gap between the chip electrode and the pad and no effective contact is formed, it is easy to cause a cold solder joint between the chip electrode and the pad during the laser welding process, which seriously affects the welding yield.

[0041] Based on this, the present application hopes to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in the subsequent embodiments.

[0042] The present embodiment provides a laser welding device, comprising: a first carrier 100, a second carrier 200 arranged above the first carrier 100, and a laser welding assembly 300 and a pressing assembly 400 arranged on the second carrier 200 and close to one side of the first carrier 100, wherein the laser welding assembly 300 and the pressing assembly 400 are arranged adjacent to each other; a side of the first carrier 100 close to the second carrier 200 is a bearing surface, and the bearing surface is configured to bear a back plate 500 and a wafer 600, and the back plate 500 and the wafer 600 are stacked in sequence on the bearing surface; the pressing assembly 400 is configured to apply pressure to the wafer 600 from one side of the wafer 600 so that the chip electrodes on the wafer 600 are in contact with the pads on the back plate 500; the laser welding assembly 300 is configured to weld the contacting chip electrodes and pads.

[0043] See also Figure 2 , Figure 2The structure diagram of a laser welding device provided in this embodiment. The laser welding device includes: a first carrier 100, a second carrier 200 arranged above the first carrier 100, and a laser welding assembly 300 and a pressing assembly 400 arranged on the second carrier 200 and close to one side of the first carrier 100, and adjacently arranged laser welding assemblies 300 and pressing assemblies 400; a side of the first carrier 100 close to the second carrier 200 is a bearing surface, and the bearing surface is used to place a back plate 500 and a wafer 600, wherein the wafer 600 and the back plate 500 are sequentially stacked on the bearing surface, and the chip electrodes and pads are aligned with each other; the pressing assembly 400 is configured to be arranged from one side of the wafer 600 to the wafer 600. The circle 600 applies pressure to make the chip electrode on the wafer 600 contact with the pad on the back plate 500. The pressing component 400 can be moved to the area where pressing is required above the wafer 600 as needed. At the same time, the downward pressure applied by the pressing component 400 to the wafer 600 can be adjusted as needed to ensure effective contact between the chip electrode and the pad; the laser welding component 300 is configured to weld the contacting chip electrodes and pads. When the pressing component 400 applies downward pressure to the wafer 600 to make the chip electrode and the pad effectively contact, the laser welding component 300 will emit laser to the welding area to achieve welding of the chip electrode and the pad.

[0044] In this embodiment, the carrying surface of the first carrier 100 is used to carry the back plate 500 and the wafer 600, wherein the first carrier 100 can be a fixed carrier or a movable carrier, which is not limited in this embodiment. The back plate 500 and the wafer 600 carried on the first carrier 100 can be placed in the order of Figure 2 The order can also be Figure 2 After the back plate 500 and the wafer 600 are placed on the carrying surface of the first carrier 100, the back plate 500 and the wafer 600 are placed in alignment, that is, the pads on the back plate 500 are placed in alignment with the electrodes of the chip on the wafer 600. After the alignment, the back plate 500 and the wafer 600 are usually pressed and fixed on the first carrier 100 to avoid relative displacement and misalignment between the back plate 500 and the wafer 600.

[0045] In this embodiment, the second stage 200 is disposed above the first stage 100. Usually, the second stage 200 is used to fix the laser welding components and auxiliary devices related to welding, wherein the fixable components include but are not limited to the welding calibration probe, the alignment detection probe, the laser welding component 300 and the pressing component 400. It can be understood that the second stage 200 can also be a fixed stage or a movable stage, which is not limited in this embodiment.

[0046] In the present embodiment, the pressing assembly 400 is configured to apply pressure to the wafer 600 from one side of the wafer 600 so that the chip electrodes on the wafer 600 are in contact with the pads on the backplane 500. In order to prevent the pressing assembly 400 from blocking the laser emission point of the laser welding assembly 300 and affecting the welding quality, the pressing assembly 400 may be arranged adjacent to the side of the laser emission point of the laser welding assembly 300. Of course, it is understandable that in some cases the pressing assembly 400 can also be integrated with the laser welding assembly 300, but in order to prevent the pressing part from blocking the laser emission point of the laser welding assembly 300 and affecting the welding quality, the pressing part is also located in the collar area of ​​the welding area instead of directly above the welding area. In the present embodiment, the area below the laser emission point of the laser welding assembly 300 is the current area to be welded. It is understandable that the pressing assembly 400 has Figure 2 In addition to the round roller, it can also be a sheet-type tablet such as Figure 3 As shown; the setting position of the pressing assembly 400 is as shown Figure 2 As shown, the pressing assembly 400 is arranged on the right side of the laser welding assembly 300, and can also be arranged on the left side of the laser welding assembly 300; the arrangement position of the pressing assembly 400 can also refer to the following rules. When the first carrier 100 and the laser welding assembly 300 undergo horizontal relative displacement, the pressing assembly 400 is arranged in front of the laser welding assembly 300; of course, in other cases, the pressing assembly 400 can also be arranged on both sides of the laser welding assembly 300 at the same time, such as Figure 4 As shown; the fixing method of the press-fit assembly 400 is in addition to Figure 2 In addition to being fixed on the second carrier 200 as shown, it can also be fixed in other ways, including but not limited to fixing with a separate fixing bracket, fixing through the first carrier 100, etc.; of course, the pressing assembly 400 can also be set in a fixed manner, and can also be set in a movable manner, which is not limited to this embodiment.

[0047] The present embodiment provides a laser welding device, which includes a pressing component 400 and a laser welding component 300. The pressing component is configured to apply pressure to the wafer 600 from one side of the wafer 600 so that the chip electrodes on the wafer 600 contact the pads on the backplane 500. After the pressing component 400 applies pressure to the wafer 600 to contact the chip electrodes on the wafer 600 with the pads on the backplane 500, the contacting chip electrodes and pads are welded by the laser welding component 300, thereby solving the problem of poor welding between the wafer 600 and the backplane 500 caused by warping.

[0048] Another optional embodiment of the present invention:

[0049] This embodiment provides some other optional methods based on a laser welding device provided by the above entity, specifically including the following methods:

[0050] In another optional embodiment, the laser welding device also includes an annular fixing component 700 disposed between the first carrier 100 and the second carrier 200, and the annular fixing component 700 is configured to apply pressure to the periphery of the wafer 600 so that the wafer 600 is aligned and fixed with the back plate 500; the pressing component 400 is configured to apply pressure to the wafer 600 located in the annular fixing component 700 so that the chip electrodes on the wafer 600 in this area and adjacent areas are in contact with the pads on the back plate 500.

[0051] See also Figure 5 , Figure 5 A top view of the first carrier of a laser welding device provided in this embodiment. An annular fixing assembly 700 is disposed above the wafer 600 between the first carrier 100 and the second carrier 200. The annular fixing assembly 700 is pressed against the periphery of the wafer 600. A blank area is usually left on the periphery of the wafer 600 to facilitate the subsequent grasping and fixing of the production process. It should be noted that in actual applications, the annular fixing assembly 700 is not limited to Figure 5 The circular ring shown may also include, but is not limited to, a rectangular ring, an elliptical ring, and a special-shaped ring in other embodiments. The specific shape of the annular fixing assembly 700 is not limited in this embodiment.

[0052] In this embodiment, the annular fixing component 700 applies pressure to the outer circle of the wafer 600, so that after the wafer is aligned and fixed with the back plate, the pressing component 400 only needs to press the area on the wafer 600 located within the annular fixing component 700. In this way, the pressing component 400 can set different pressing pressures according to the degree of warping in different areas to achieve better welding effect.

[0053] In another optional embodiment, the annular fixing assembly 700 includes: a fixing buckle 701, and a plurality of telescopic connecting rods 702 disposed on the periphery of the fixing buckle 701;

[0054] One end of the telescopic link 702 is telescopically connected to the second stage 200, and the other end is movably connected to the fixed buckle 701. The telescopic link 702 is configured to control the lifting and lowering of the fixed buckle 701, and to adjust the pressure applied by the fixed buckle 701 to the wafer 600;

[0055] Alternatively, one end of the telescopic link 702 is fixedly connected to the first carrier 100 , and the other end is movably connected to the fixed buckle 701 . The telescopic link 702 is configured to control the lifting and lowering of the fixed buckle 701 , and to adjust the pressure applied by the fixed buckle 701 to the wafer 600 .

[0056] See also Fig. 9 , Fig. 9 The schematic diagram of the structure of a laser welding device provided in this embodiment. The annular fixing assembly 700 includes: a fixing buckle 701, and a plurality of telescopic connecting rods 702 arranged on the periphery of the fixing buckle 701; one end of the telescopic connecting rod 702 is telescopically connected to the second carrier 200, and the other end is movably connected to the fixing buckle 701. The telescopic connecting rod 702 is configured to control the lifting and lowering of the fixing buckle 701, and to adjust the pressure applied by the fixing buckle 701 to the wafer 600. Fig. 9 The first carrier 100 can move in direction A to drive the back plate 500 and the wafer 600 to move in direction A. Since the fixing buckle 701 is pressed and fixed on the wafer 600, the fixing buckle 701 also needs to move in direction A. In order to realize the movement of the fixing buckle 701 in direction A, the telescopic connecting rod 702 connected thereto needs to change the length of the telescopic connecting rod 702 by telescoping according to the moving direction of the fixing buckle 701.

[0057] See also Fig.10 , Fig.10 A schematic diagram of the structure of a laser welding device provided in this embodiment. The annular fixing assembly 700 includes: a fixing buckle 701, and a plurality of telescopic connecting rods 702 arranged on the periphery of the fixing buckle 701; one end of the telescopic connecting rod 702 is fixedly connected to the first carrier 100, and the other end is movably connected to the fixing buckle 701, and the telescopic connecting rod 702 is configured to control the lifting and lowering of the fixing buckle 701, and adjust the magnitude of the pressure applied by the fixing buckle 701 to the wafer 600. Fig.10 The first carrier 100 can move in direction A to drive the back plate 500 and the wafer 600 to move in direction A. Since the fixing ring 701 is connected and fixed to the first carrier 100, the fixing ring 701 will also move with the first carrier 100. Fig.10 The fixing ring 701 in the Fig. 9 The length of the telescopic connecting rod 702 is adjusted according to the moving direction as in FIG.

[0058] In another optional embodiment, the pressing assembly 400 includes a pressing portion and a connecting portion, the pressing portion is connected to the second carrier through the connecting portion, and the pressing portion can roll along a direction perpendicular to an extension direction of the connecting portion.

[0059] See also Figure 2 and Figure 4 , Figure 2 and Figure 4 The pressing assembly 400 includes a pressing part 407 and a connecting part 406, wherein the pressing part 406 is a component that contacts the pressing assembly 400 with the wafer 600, the pressing part 406 can roll on the upper surface of the wafer 600, and the connecting part 407 is used to connect the pressing part 406 and the second carrier 200, wherein the pressing part 406 is connected to the second carrier 200 through the connecting part 407, and the pressing part 406 can roll along a direction perpendicular to the extension direction of the connecting part 407, and the pressing part 406 can be rolled by rolling the pressing part 406 without lifting the pressing assembly 400 to achieve horizontal relative movement between the pressing assembly 400 and the first carrier 100, and the pressing assembly 400 can be moved to the current area to be welded or the adjacent area of ​​the current area to be welded of the wafer 600 by rolling, thereby improving the welding efficiency. It should be noted that Figure 3 The press-fit assembly 400 is Figure 2 and 4 Not the same, Figure 3 The pressing part of the pressing assembly 400 is a flat pressing part and cannot roll, so when the pressing assembly 400 needs to be moved, the flat pressing part needs to be lifted first. It should be noted that the current area to be welded refers to the area that needs to be welded at present, which is usually the area corresponding to the location of the electrode of the chip. The pressing part 406 can be set in a way of surrounding the current area to be welded, or in a way of being set in the collar area of ​​the current area to be welded to apply pressure to the wafer 600, so that the chip electrode contacts the pad.

[0060] In another optional embodiment, the pressing part 407 includes a roller shaft 401, and the connecting part 406 includes a first connecting rod 402 and a second connecting rod 403, and one end of the first connecting rod 402 and the second connecting rod 403 are respectively connected to two ends of the roller shaft 401 through a bearing;

[0061] The other ends of the first connecting rod 402 and the second connecting rod 403 are disposed on the second stage 200 .

[0062] See also Fig.11 , Fig.11 For this embodiment Fig. 9 A schematic diagram of the structure of a left view of a laser welding device is provided. The pressing part 407 includes a roller 401, and the connecting part 406 includes a first connecting rod 402 and a second connecting rod 403 and a bearing. Fig.11 The bearings in the embodiment include a first bearing 404 and a second bearing 405, Fig.11The first connecting rod 402 and the second connecting rod 403 are perpendicular to the roller shaft 401 and are respectively arranged at the two ends of the roller shaft 401, the first bearing 404 is arranged at the end of the roller shaft 401 and fixed to the first connecting rod 402, and the second bearing 405 is arranged at the other end of the roller shaft 401 and fixed to the second connecting rod 403; the other end of the first connecting rod 402 opposite to the first bearing 404 is movably connected to the side of the second platform 200 close to the first platform 100, and the other end of the second connecting rod 403 opposite to the second bearing 405 is movably connected to the side of the second platform 200 close to the first platform 100.

[0063] In another optional embodiment, the pressing portion includes a roller and a fixed shaft, the roller is sleeved on the fixed shaft, and the fixed shaft is connected to the second carrier through the connecting portion.

[0064] See also Fig.12 , Fig.12 FIG. 4 is a schematic diagram of another laser welding device provided in this embodiment. The pressing part 407 includes a roller 401 and a fixed shaft 408. The roller 401 is sleeved on the fixed shaft 408. The fixed shaft 408 is connected to the second carrier 200 through the connecting part 406. It can be understood that the fixed shaft 408 has the following structure: Fig.12 In addition to being arranged at the end of the roller 401 as shown, it can be arranged at any position in the middle of the roller 401.

[0065] In another optional embodiment, the roller shaft 401 includes a telescopic part and a fixed part, and the telescopic part is sleeved in the fixed part; the telescopic part can be telescoped along the axial direction of the roller shaft, so that the axial length of the roller shaft 401 varies between the laser radiation length of the laser welding assembly 300 and the inner diameter of the annular fixing assembly 700.

[0066] In this embodiment, when the fixing buckle 701 in the annular fixing assembly 700 is a buckle similar to a circular one, the length of the line segment perpendicular to the symmetry axis when moving from the center of the circle along the symmetry axis to the edge of the circle will gradually become shorter. In order to allow the roller 401 to press the area to be welded at the edge of the wafer 600, the roller 401 can be set as a roller 401 with a retractable length, and the retractable length of the roller 401 can be changed by a motor or a threaded rod. Of course, in other cases, when the thickness of the fixing buckle 701 in the annular fixing assembly 700 is relatively thin, for example, when the thickness is less than or equal to 50 μm, the two sides of the roller 401 can also be pressed onto the fixing buckle 701 to achieve the pressing of the area to be welded at the edge of the wafer 600. It can be understood that, in addition to being arranged in the fixing part as mentioned above, the retractable part in the roller 401 can also be arranged at both ends of the fixing part or only at one end of the fixing part, and the retractable part at both ends or one end is respectively extended to both ends or one end to achieve the change of the length of the roller 401.

[0067] In another optional embodiment, a pressure adjustment assembly 900 is further provided between the first connecting rod 402 and the second connecting rod 403 and the second carrier 200 ; the pressure adjustment assembly 900 is configured to adjust the length of the first connecting rod 402 and the second connecting rod 403 to adjust the pressure applied by the roller 401 to the wafer 600 .

[0068] See also Fig.13 , Fig.13 This is a schematic structural diagram of a laser welding device provided in this embodiment. Fig.10 A pressure regulating assembly 900 is also provided between the first connecting rod 402, the second connecting rod 403 and the second carrier 200. The pressure regulating assembly 900 is configured to adjust the length of the first connecting rod 402 and the second connecting rod 403 to adjust the pressure applied by the roller 401 to the wafer 600. The pressure regulating assembly 900 may optionally include but is not limited to a hydraulic telescopic assembly, an inclined pull assembly and a screw telescopic assembly. The hydraulic telescopic assembly and the screw telescopic assembly both adjust the length of the first connecting rod 402 and the second connecting rod 403 by changing the thickness of their protrusions by telescoping. The inclined pull assembly adjusts the position of the first connecting rod 402 and the second connecting rod 403 by controlling the angle between the first connecting rod 402 and the second connecting rod 403 and the second carrier 200. It can be understood that the laser welding device in this embodiment also includes a pressure sensor assembly, which can collect the downward pressure value of the pressing assembly 400 and the downward pressure value of the annular fixing assembly 700, and control the corresponding assembly to adjust the pressing pressure generated on the corresponding assembly through the collected downward pressure value.

[0069] In another optional embodiment, the first carrier 100 includes a first driving assembly 101, and the first driving assembly 101 is configured to drive the first carrier 100 to move horizontally, so that the pressing assembly 400 and the first carrier 100 move horizontally relative to each other;

[0070] And / or, the second stage 200 includes a second driving assembly 201, and the second driving assembly 201 is configured to drive the second stage 200 to move horizontally and drive the pressing assembly 400 to move horizontally, so that the pressing assembly 400 and the first stage 100 move horizontally relative to each other;

[0071] And / or, it also includes a third driving component 800 disposed between the second carrier 200 and the pressing component 400, and the third driving component 800 is configured to drive the pressing component 400 to move horizontally so that the pressing component 400 and the second carrier 200 move horizontally relative to each other.

[0072] like Figure 6 As shown, the first carrier 100 includes a first driving component 101, and the first driving component 101 can drive the first carrier 100 to move horizontally in direction A, so that the pressing component 400 and the first carrier 100 move horizontally relative to each other. The first carrier 100 is moved in this way, and the movement of the first carrier 100 drives the back plate 500 and the wafer 600 to move, thereby completing the laser welding of all light-emitting chips.

[0073] like Figure 7 As shown, the second carrier 200 includes a second driving component 201, which can drive the second carrier 200 to move horizontally in direction B. The pressing component 400 moves together with the second carrier 200, thereby realizing horizontal relative movement of the pressing component 400 and the first carrier 100, thereby completing laser welding of all light-emitting chips.

[0074] like Figure 8 As shown, the laser welding device also includes a third driving component 800 arranged between the second carrier 200 and the pressing assembly 400. The movement of the third driving component 800 drives the pressing assembly 400 to move horizontally in direction C, so that the pressing assembly 400 and the first carrier 100 move horizontally relative to each other, thereby completing the laser welding of all light-emitting chips.

[0075] In another optional embodiment, the horizontal distance between the laser emission point of the laser welding assembly 300 and the roller 401 is a first preset distance;

[0076] The first preset distance is greater than or equal to the length of the electrode of the chip and less than or equal to the length of n chips, where n is less than or equal to 5.

[0077] See also Fig.14 , Fig.14A schematic diagram of a partially enlarged structure of a laser welding device provided in this embodiment. The horizontal spacing between the laser emission point of the laser welding assembly 300 and the roller 401 is a first preset distance L, which is usually a fixed value and does not change with the horizontal relative movement of the roller 401 and the first carrier 100. The first preset distance L usually satisfies the requirement of being greater than or equal to the length of the chip electrode and less than or equal to the length of n chips, where n is less than or equal to 5. The first preset distance L is greater than or equal to the length of the chip electrode to avoid the pressing assembly 400 from blocking the laser to ensure the welding quality, and is less than the length of n chips, where n is less than or equal to 5. Here, the value of n of 5 is an empirical value. The size of the existing micro-LED chip is between 50μm-200μm. When n is less than or equal to 5, it can be ensured that the wafer 600 does not warp and prevents the occurrence of cold solder joints. Of course, it is understandable that the value of n will change according to different chip sizes and types, as well as the performance of the wafer 600, and can be adjusted as needed. It should be noted that, in other embodiments, when the pressing assembly 400 includes a roller 401, the diameter of the roller 401 also needs to be limited according to actual conditions. The purpose of limiting the diameter of the roller 401 is to avoid the roller 401 being too thick, which causes the force point of the roller 401 to be too far away from the laser emission point of the laser welding assembly 300. Too far a distance will cause the horizontal distance between the laser emission point of the laser welding assembly 300 and the current area to be welded on the back plate 500 and the wafer 600 to fail to meet the requirements of the first preset distance. Under normal circumstances, the diameter of the roller 401 is required to be smaller than the first preset distance.

[0078] Another optional embodiment of the present invention:

[0079] This embodiment provides a laser welding method, comprising:

[0080] Provided is a laser welding device of the present application;

[0081] A back plate and a wafer are sequentially stacked on the carrying surface of the first carrier;

[0082] Placing the pressing assembly on top of the wafer and applying pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer contact the pads on the backplane;

[0083] The laser welding component is controlled to weld the contacting chip electrodes and pads.

[0084] See also Fig.15 , Fig.15 The following is a schematic diagram of a laser welding method provided in this embodiment. The laser welding method includes the following steps:

[0085] S101. Provide a laser welding device of the present application.

[0086] S102 , stacking a back plate and a wafer in sequence on a carrying surface of a first carrier.

[0087] S103, placing the pressing assembly above the wafer and applying pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer are in contact with the pads on the backplane.

[0088] S104, controlling the laser welding assembly to weld the contacting chip electrodes and pads.

[0089] A laser welding method provided in this embodiment is applied in a laser welding device provided in this application, wherein a pressing assembly is placed above a wafer, and the pressing assembly applies pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer contact the pads on the backplane, and then the contacting chip electrodes and the pads are welded by a laser welding assembly, thereby solving the problem of poor welding between the wafer and the backplane caused by warping.

[0090] In some embodiments, the laser welding method may further include the steps of:

[0091] After step S102, the method further includes controlling the annular fixing assembly to apply pressure to the periphery of the wafer so that the wafer and the back plate are aligned and fixed.

[0092] After the wafer and the back plate are aligned and fixed by the annular fixing component, the chip to be welded on the wafer is located in the annular fixing component, and the corresponding pressing component only needs to apply pressure to the wafer located in the annular fixing component.

[0093] The above-mentioned control annular fixing component applies pressure to the periphery of the wafer, wherein the annular fixing component can be connected to the second carrier to align and fix the wafer and the back plate, and can also be connected to the first carrier to align and fix the wafer and the back plate.

[0094] In some embodiments, in step S103 of the above-mentioned laser welding method, the pressing assembly includes a pressing part and a connecting part, the pressing part is connected to the second carrier through the connecting part, and the pressing part can roll along a direction perpendicular to the extension direction of the connecting part. The pressing part moves horizontally on the wafer by rolling, which can increase the transfer speed of the pressing assembly and improve the welding efficiency.

[0095] The above-mentioned pressing part further includes a roller shaft and a first connecting rod and a second connecting rod. The two ends of the roller shaft are connected to the first connecting rod and the second connecting rod through bearings respectively. The other ends of the first connecting rod and the second connecting rod are arranged on the second platform. The downward pressure generated by the first connecting rod and the second connecting rod on the roller shaft can be adjusted by adjusting the length of the first connecting rod and the second connecting rod or the angle between the first connecting rod and the second platform, so that the roller shaft applies pressure to the wafer. At the same time, the roller shaft itself can also roll on the wafer to achieve horizontal movement of the pressing assembly. Alternatively, the pressing part further includes a roller shaft and a fixed shaft. The roller shaft is sleeved on the fixed shaft. The fixed shaft is connected to the second platform through the connecting part. The downward pressure generated by the fixed shaft on the roller shaft can be adjusted by adjusting the length of the fixed shaft or the angle between the fixed shaft and the second platform, so that the roller shaft applies pressure to the wafer. At the same time, the roller shaft itself can also roll on the wafer to achieve horizontal movement of the pressing assembly.

[0096] The above-mentioned pressing part realizes the horizontal movement of the pressing assembly on the wafer by rolling the roller. Considering that the internal shape of the annular fixing assembly may not be rectangular in some cases, for example, it may be circular or elliptical, in order to allow the roller to apply pressure to both the center and edge parts of the wafer area corresponding to the circle, the roller at this time includes a telescopic part and a fixed part, and the fixed part is used to fix the telescopic part. The telescopic part can be telescoped and changed in length in the axial direction, so that the axial length of the roller can vary between the laser radiation length of the laser welding assembly and the inner diameter of the annular fixing assembly.

[0097] In some embodiments, the laser welding method may further include the steps of:

[0098] Detect the wafer area where the roller is located, and adjust the length of the connection part according to the detection result to adjust the pressure applied by the roller to the wafer. The way in which the pressure regulating component adjusts the length of the connection part includes but is not limited to adjusting the length of the connection part by changing its own thickness, and adjusting the length of the connection part by adjusting the expansion and contraction of the connection part. The pressure regulating component adjusts the pressure applied by the roller to the wafer according to the detected wafer area where the roller is located. This is in consideration of the different degrees of warping in different areas of the wafer, so different pressures need to be applied to different areas of the wafer. For example, the central area of ​​the wafer has the highest degree of warping, and the area closer to the annular fixing component on the wafer has a lower degree of warping. Therefore, when the roller is located in the central area of ​​the wafer, the maximum pressure is applied to the wafer. When the roller moves from the central area of ​​the wafer to the edge close to the annular fixing component, the pressure applied to the wafer begins to gradually decrease. In this embodiment, the pressure regulating component adjusts the connection part to adjust the pressure applied by the roller to the wafer. The value needs to be adjusted according to the size of the wafer and the thickness of the wafer.

[0099] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A laser welding device, characterized in that: include: A first carrier, a second carrier disposed above the first carrier, and a laser welding assembly and a pressing assembly disposed on the second carrier and close to one side of the first carrier, wherein the laser welding assembly and the pressing assembly are disposed adjacent to each other; A side of the first stage close to the second stage is a carrying surface, and the carrying surface is configured to carry a back plate and a wafer, and the back plate and the wafer are sequentially stacked on the carrying surface; The pressing assembly is configured to apply pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer contact with the pads on the backplane; The laser welding assembly is configured to weld the contacted chip electrodes and pads.

2. The laser welding device according to claim 1, characterized in that: Also included is an annular fixing assembly disposed between the first carrier and the second carrier, wherein the annular fixing assembly is configured to apply pressure to the periphery of the wafer so that the wafer and the back plate are aligned and fixed; The press assembly is configured to apply pressure to the wafer within the annular fixture assembly.

3. The laser welding device according to claim 2, characterized in that: The annular fixing assembly comprises: a fixing buckle, and a plurality of telescopic connecting rods arranged on the periphery of the fixing buckle; One end of the telescopic link is telescopically connected to the second carrier, and the other end is movably connected to the fixed buckle, and the telescopic link is configured to control the lifting and lowering of the fixed buckle, and adjust the pressure applied by the fixed buckle on the wafer; Alternatively, one end of the telescopic link is fixedly connected to the first carrier, and the other end is movably connected to the fixed buckle, and the telescopic link is configured to control the lifting and lowering of the fixed buckle, and to adjust the pressure applied by the fixed buckle on the wafer.

4. The laser welding device according to claim 2, characterized in that: The pressing assembly includes a pressing portion and a connecting portion. The pressing portion is connected to the second carrier through the connecting portion, and the pressing portion can roll along a direction perpendicular to an extending direction of the connecting portion.

5. The laser welding device according to claim 4, characterized in that: The pressing part includes a roller shaft, and the connecting part includes a first connecting rod and a second connecting rod, and one end of the first connecting rod and one end of the second connecting rod are respectively connected to two ends of the roller shaft through a bearing; The other ends of the first connecting rod and the second connecting rod are arranged on the second carrier.

6. The laser welding device according to claim 4, characterized in that: The pressing part includes a roller shaft and a fixed shaft, the roller shaft is sleeved on the fixed shaft, and the fixed shaft is connected to the second carrier through the connecting part.

7. The laser welding device according to claim 6, characterized in that: The roller shaft comprises a telescopic part and a fixed part, the telescopic part is sleeved in the fixed part, and the fixed part is sleeved on the fixed shaft; The telescopic portion can be telescopic along the axial direction of the fixing shaft, so that the axial length of the roller shaft changes between the laser irradiation length of the laser welding component and the inner diameter of the annular fixing component.

8. The laser welding device according to any one of claims 5 to 7, characterized in that: A pressure regulating component is also provided between the connecting portion and the second carrier; The pressure adjustment assembly is configured to adjust the length of the connecting portion to adjust the pressure applied by the roller to the wafer.

9. The laser welding device according to any one of claims 1 to 7, characterized in that: The first carrier includes a first driving assembly, and the first driving assembly is configured to drive the first carrier to move relative to the pressing assembly; And / or, the second stage includes a second driving component, and the second driving component is configured to drive the second stage to move as a whole relative to the first stage; And / or, it also includes a third driving component arranged between the second carrier and the pressing assembly, and the third driving component is configured to drive the pressing assembly to move relative to the second carrier.

10. A laser welding method, characterized in that: include: Providing a laser welding device as described in any one of claims 1 to 9; The back plate and the wafer are sequentially stacked on the carrying surface of the first carrier; Placing the pressing assembly above the wafer and applying pressure to the wafer from one side of the wafer so that the chip electrodes on the wafer are in contact with the pads on the backplane; The laser welding assembly is controlled to weld the chip electrodes and the pads that are in contact.

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