Reprinting device for circuit board defective products and process thereof

Abstract

The invention relates to the field of circuit board printing, and discloses a reprinting device for circuit board defective products and a process thereof.The reprinting device for the circuit board defective products comprises two fixing plates, the two fixing plates are fixed to the top face of a workbench, and the top face of a printing box communicates with a fixed feeding pipe; a first conveying pump is arranged on the feeding pipe, a plurality of discharging holes are formed in the inner bottom face of the printing box, discharging pipes are fixed to the interiors of the discharging holes respectively, and second conveying pumps are arranged on the discharging pipes respectively. According to the device, through cooperative use of the first guide rail, the fixing frame, the first electric push rod, the printing box, a plurality of discharging pipes, a plurality of second conveying pumps, a second electric push rod, a placement table, an L-shaped frame and a printing plate, local printing of circuit board defective products is facilitated, traditional overall printing is avoided, waste of solder paste is reduced, and the production efficiency is improved. Therefore, the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board printing, and in particular to a reprinting device and a process for defective circuit boards. Background Art

[0002] Circuit board is one of the key components in electronic equipment, which provides electrical connection and support for electronic components. With the continuous development of electronic product technology, the production accuracy and functional requirements of circuit boards are also constantly improving. However, in the assembly process of circuit boards, solder paste printing is one of the key steps. The accurate printing of solder paste is crucial to the electrical performance, connection quality and long-term stability of the circuit board. However, in mass production, due to improper machine adjustment, material problems or human operating errors, the solder paste may be unevenly distributed or insufficient, and the defective circuit boards need to be reprinted.

[0003] At present, when most defective circuit boards are reprinted through a printing device, solder paste is usually reprinted on the entire board. Therefore, there are the following disadvantages: the defective circuit board cannot be partially printed during printing, which increases the waste of solder paste and thus increases production costs. Summary of the invention

[0004] The purpose of the present invention is to provide a reprinting device and process for defective circuit boards to solve the problem that the defective circuit boards cannot be partially printed during printing, thereby increasing the waste of solder paste and thus increasing the production cost.

[0005] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme: a reprinting device for defective circuit boards, comprising two fixing plates, the two fixing plates are respectively fixed on the top surface of the workbench, the inner sides of the two fixing plates are respectively provided with fixing grooves, a PLC controller is fixed on the front side of the workbench, first guide rails are respectively fixed inside the two fixing grooves, the first guide rails are electrically connected to the PLC controller, a fixing frame is fixed between the sliders of the two first guide rails, a first electric push rod is fixed on the inner top surface of the fixing frame, the first electric push rod is electrically connected to the PLC controller, a connecting frame is fixed to one end of the telescopic rod of the first electric push rod, a printing box is fixed on the bottom surface of the connecting frame, and the top surface of the printing box A feed pipe is connected and fixed, a first delivery pump is arranged on the feed pipe, the first delivery pump is electrically connected to the PLC controller, a plurality of discharge holes are arranged on the inner bottom surface of the printing box, discharge pipes are respectively fixed inside the plurality of discharge holes, a second delivery pump is respectively arranged on the plurality of discharge pipes, the second delivery pump is electrically connected to the PLC controller, a mounting groove is arranged on the top surface of the workbench, a second electric push rod is fixed inside the mounting groove, the second electric push rod is electrically connected to the PLC controller, a placing table is fixed on one end of the telescopic rod of the second electric push rod, two L-shaped frames are movably arranged above the workbench, a printing plate is arranged between the two L-shaped frames, a plurality of printing holes are arranged on the top surface of the printing plate.

[0006] Preferably, an automatic optical detector is fixed on the right side of the workbench, and the automatic optical detector is electrically connected to the PLC controller. Second guide rails are respectively fixed to the inner sides of the two fixed plates, and a movable plate is fixed between the sliders of the two second guide rails. A CCD camera is fixed on the bottom surface of the movable plate, and the CCD camera is electrically connected to the PLC controller.

[0007] Preferably, a scraper is detachably provided on the front side of the outer wall of the printing box.

[0008] Preferably, the front side of the outer wall of the printing box is provided with a plurality of threaded grooves, the front side of the scraper is provided with a plurality of threaded holes, the plurality of threaded holes are respectively threadedly connected with bolts, and the threaded ends of the plurality of bolts are respectively threadedly connected with the internal threads of the plurality of threaded grooves.

[0009] Preferably, a movable groove is provided on the top surface of the placing table, movable holes are provided on the left and right sides of the placing table respectively, two clamping plates are movably provided inside the movable groove, third electric push rods are fixed on the left and right sides of the placing table respectively, and one end of the two telescopic rods of the third electric push rods are fixedly connected to the outer sides of the two clamping plates respectively.

[0010] Preferably, connecting grooves are respectively opened on the inner sides of the two fixing plates, and fourth electric push rods are respectively fixed inside the two connecting grooves, and one end of the telescopic rods of the two fourth electric push rods is respectively fixedly connected to the outer sides of the two L-shaped frames.

[0011] Preferably, a plurality of fifth electric push rods are respectively fixed to the inner sides of the two L-shaped frames.

[0012] Preferably, a measuring rod is fixed between the two fixing plates, a scale is provided on the front side of the measuring rod, and measuring plates are respectively fixed on the top surfaces of the two L-shaped frames.

[0013] The present invention also provides a reprinting process for defective circuit boards, comprising the following steps:

[0014] S1: The staff first connects the feed pipe to the solder paste storage device (not shown in the figure), and injects an appropriate amount of solder paste into the printing box through the first delivery pump. Then the staff activates the fourth electric push rod to enable the L-shaped frame to move left and right, adjusts the distance between the two L-shaped frames, and then places the printed board on the two L-shaped frames. Then, the staff activates the fifth electric push rod so that one end of its telescopic rod contacts the top surface of the printed board and presses and fixes the printed board. Then, the staff places the defective circuit board on the top surface of the placement table;

[0015] S2: When the circuit board is placed, the staff starts the second electric push rod to raise the placement table and the circuit board until the circuit board fits with the bottom surface of the printed board. The second guide rail is started to enable the slider to move back and forth, thereby driving the moving plate and the CCD camera to move back and forth. When the CCD camera moves to the top of the circuit board, it automatically captures the image of the circuit board and transmits the data to the automatic optical detector.

[0016] S3: After receiving the data, the automatic optical inspection instrument uses the image processing algorithm to quickly identify the location where the solder paste is missing on the circuit board, and feeds back the location information of the defective area to the PLC controller. Based on this information, the PLC controller controls the first guide rail to automatically move the fixed frame and the printing box to the defective area.

[0017] S4: The PLC controller controls the first electric push rod to make the connecting frame and the printing box descend to the top surface of the printing board, and then starts the second delivery pump on the discharge pipe corresponding to the position where the solder paste on the circuit board is missing, squeezes the solder paste in the printing box, enters the printing hole of the printing board through the discharge pipe, and squeezes the solder paste to the position where the solder paste on the circuit board is missing;

[0018] S5: When the printing box moves, it can drive the scraper to move, and then can scrape the solder paste on the printed board, squeeze the solder paste to the surface of the circuit board, and complete the printing work on the circuit board.

[0019] Compared with the prior art, a reprinting device for defective circuit boards using the above technical solution has the following beneficial effects:

[0020] 1. During use, the staff first connects the feed pipe to the solder paste storage device (not shown in the figure), and injects an appropriate amount of solder paste into the printing box through the first delivery pump. Then the staff places the defective circuit board on the top surface of the placement table, and starts the second electric push rod to make the placement table and the circuit board rise until the circuit board fits with the bottom surface of the printed board. Then the slider of the first guide rail is started to move back and forth, thereby driving the fixed frame, the connecting frame and the printing box to move synchronously, so that the printing box moves to above the position where the solder paste on the circuit board is missing. Then the first electric push rod is started to make the connecting frame and the printing box descend to the top surface of the printing board. Then the second delivery pump on the discharge pipe corresponding to the position where the solder paste on the circuit board is missing is started to squeeze the solder paste in the printing box, enter the printing hole of the printing board through the discharge pipe, and squeeze the solder paste to the position where the solder paste on the circuit board is missing. The coordinated use of the first guide rail, the fixing frame, the first electric push rod, the printing box, the plurality of discharge pipes, the plurality of second delivery pumps, the second electric push rod, the placement table, the L-shaped frame and the printing plate facilitates partial printing of defective circuit boards, avoids traditional overall printing, reduces the waste of solder paste, and thus reduces production costs;

[0021] 2. During use, when the CCD camera moves to the top of the circuit board, it automatically captures the circuit board image and transmits the data to the automatic optical detector. The automatic optical detector uses the image processing algorithm to quickly identify the location where the solder paste is missing on the circuit board, and feeds back the location information of the defective area to the PLC controller. Based on this information, the PLC controller controls the first guide rail to automatically move the fixed frame and the printing box to the defective area, realizing automatic printing and soldering of the defective area, thereby improving the automation of the printing process and reducing the complexity and error of manual operation.

[0022] 3. During use, when the printing box moves, it can drive the scraper to move, and then it can scrape the solder paste on the printed board, squeeze the solder paste to the surface of the circuit board, complete the printing of the circuit board, and achieve uniform application of the solder paste. The use of the threaded groove and the bolt is convenient for the staff to disassemble and assemble the scraper, and then it is convenient for the staff to clean or replace the scraper. After the staff places the circuit board on the top surface of the placement table, by starting the third electric push rod, the two clamping plates are close to each other, and the circuit board can be clamped and fixed, ensuring the stability of the circuit board during the printing process and preventing the decline in printing quality due to the movement of the circuit board;

[0023] Fourth, during use, the L-shaped frame can be moved left and right by starting the fourth electric push rod, which makes it easier for the staff to adjust the distance between the two L-shaped frames, and can place printing plates of different sizes, thereby improving the flexibility and practicality of the device. After the staff places the printing plate between the two L-shaped frames, the fifth electric push rod is started so that one end of its telescopic rod contacts the top surface of the printing plate, and the printing plate is pressed and fixed, thereby ensuring the stability of the printing plate during the printing process and preventing the printing quality from being reduced due to the movement of the printing plate. When adjusting the distance between the two L-shaped frames, the staff can accurately measure the distance between the two L-shaped frames by observing the movement of the measuring plate in front of the measuring rod and the scale value on the ruler, which not only provides intuitive measurement data, but also ensures the accuracy of the distance between the L-shaped frames. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a three-dimensional schematic diagram of an embodiment.

[0025] Figure 2 It is an exploded schematic diagram of an embodiment.

[0026] Figure 3 It is a schematic diagram of the explosion of the fixed frame and the scraper in the embodiment.

[0027] Figure 4 It is a cross-sectional schematic diagram of the printing box in the embodiment.

[0028] Figure 5 It is an exploded schematic diagram of the placement table and the clamping plate in the embodiment.

[0029] Figure 6 It is a schematic diagram of the explosion of the fixed plate and the L-shaped frame in the embodiment.

[0030] Figure 7 For example Figure 2 Enlarged schematic diagram at point A in the middle.

[0031] In the figure: 1, fixed plate; 2, workbench; 3, fixed groove; 4, first guide rail; 5, fixed frame; 6, first electric push rod; 7, connecting frame; 8, printing box; 9, feeding pipe; 10, first delivery pump; 11, discharge hole; 12, discharge pipe; 13, second delivery pump; 14, mounting groove; 15, second electric push rod; 16, placement table; 17, L-shaped frame; 18, printing plate; 19, automatic optical detector; 20, second guide rail; 21, moving plate; 22, CCD camera; 23, scraper; 24, threaded groove; 25, threaded hole; 26, bolt; 27, movable groove; 28, movable hole; 29, clamping plate; 30, third electric push rod; 31, connecting groove; 32, fourth electric push rod; 33, fifth electric push rod; 34, measuring rod; 35, scale; 36, measuring plate. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0033] like Figure 1-Figure 7 As shown, a reprinting device for defective circuit boards comprises two fixing plates 1, the two fixing plates 1 are fixed to the top surface of a workbench 2, fixing grooves 3 are respectively provided on the inner sides of the two fixing plates 1, a PLC controller is fixed to the front side of the workbench 2, first guide rails 4 are respectively fixed inside the two fixing grooves 3, the first guide rails 4 are electrically connected to the PLC controller, a fixing frame 5 is fixed between the sliders of the two first guide rails 4, a first electric push rod 6 is fixed to the inner top surface of the fixing frame 5, the first electric push rod 6 is electrically connected to the PLC controller, a connecting frame 7 is fixed to one end of the telescopic rod of the first electric push rod 6, a printing box 8 is fixed to the bottom surface of the connecting frame 7, the top surface of the printing box 8 is connected to a fixed feed pipe 9, and a first feed pipe 9 is provided on the feed pipe 9 A delivery pump 10 is provided on the inner bottom surface of the printing box 8, and a delivery pipe 12 is fixed inside each of the delivery holes 11. Second delivery pumps 13 are provided on each of the delivery pipes 12, and the second delivery pump 13 is electrically connected to the PLC controller. A mounting groove 14 is provided on the top surface of the workbench 2, and a second electric push rod 15 is fixed inside the mounting groove 14, and the second electric push rod 15 is electrically connected to the PLC controller. A placement table 16 is fixed on one end of the telescopic rod of the second electric push rod 15, and two L-shaped frames 17 are movably provided above the workbench 2, and a printing plate 18 is provided between the two L-shaped frames 17, and a plurality of printing holes are provided on the top surface of the printing plate 18.

[0034] During use, the staff first connects the feed pipe 9 to the solder paste storage device (not shown in the figure), and injects an appropriate amount of solder paste into the printing box 8 through the first delivery pump 10. Then the staff places the defective circuit board on the top surface of the placement table 16, and starts the second electric push rod 15 to make the placement table 16 and the circuit board rise until the circuit board is in contact with the bottom surface of the printed board 18. Then the slider of the first guide rail 4 is started to move back and forth, thereby driving the fixed frame 5, the connecting frame 7 and the printing box 8 to move synchronously, so that the printing box 8 moves to above the position where the solder paste on the circuit board is missing, and then the first electric push rod 6 is started to make the connecting frame 7 and the printing box 8 descend to the top surface of the printing board 18, and then the second delivery pump 13 on the discharge pipe 12 corresponding to the position where the solder paste on the circuit board is missing is started to squeeze the solder paste in the printing box 8, and enter the printing hole of the printing board 18 through the discharge pipe 12, and squeeze the solder paste to the position where the solder paste on the circuit board is missing.

[0035] Through the coordinated use of the first guide rail 4, the fixing frame 5, the first electric push rod 6, the printing box 8, the plurality of discharge pipes 12, the plurality of second delivery pumps 13, the second electric push rod 15, the placement table 16, the L-shaped frame 17 and the printing plate 18, it is convenient to realize the partial printing of defective circuit boards, avoid the traditional overall printing, reduce the waste of solder paste, and thus reduce the production cost.

[0036] like Figure 1 , Figure 2 and Figure 5-Figure 7 As shown, an automatic optical detector 19 is fixed to the right side of the workbench 2. The automatic optical detector 19 is a prior art. The model of the automatic optical detector 19 is Koh Young Zenith 2. The automatic optical detector 19 is electrically connected to the PLC controller. Second guide rails 20 are fixed to the inner sides of the two fixed plates 1 respectively. A movable plate 21 is fixed between the sliders of the two second guide rails 20. A CCD camera 22 is fixed to the bottom surface of the movable plate 21. The CCD camera 22 is a prior art. The model of the CCD camera 22 is Teledyne DALSA Genie Nano. The CCD camera 22 is electrically connected to the PLC controller.

[0037] During use, after the staff places the circuit board on the top surface of the placement table 16, the second guide rail 20 is started to enable the slider to move forward and backward, thereby driving the movable plate 21 and the CCD camera 22 to move forward and backward. When the CCD camera 22 moves to the top of the circuit board, it automatically captures the image of the circuit board and transmits the data to the automatic optical detector 19. The automatic optical detector 19 uses an image processing algorithm to quickly identify the location where the solder paste is missing on the circuit board, and feeds back the location information of the defective area to the PLC controller. Based on this information, the PLC controller controls the first guide rail 4 to make the fixing frame 5 and the printing box 8 automatically move to the defective area, and then controls the first electric push rod 6 to move the printing box 8 downward, and at the same time controls the second electric push rod 15 to move the placement table 16 and the circuit board upward, so that the circuit board and the printing plate 18 are fitted together, and then controls the second delivery pump 13 on the corresponding discharge pipe 12 to realize automatic printing and tin replenishment of the defective area, thereby improving the degree of automation of the printing process and reducing the complexity and error of manual operation.

[0038] like Figure 1-Figure 5As shown, a scraper 23 is detachably provided on the front side of the outer wall of the printing box 8, a plurality of threaded grooves 24 are provided on the front side of the outer wall of the printing box 8, a plurality of threaded holes 25 are provided on the front side of the scraper 23, bolts 26 are threadedly connected in the plurality of threaded holes 25, and the threaded ends of the plurality of bolts 26 are respectively threadedly connected with the internal threads of the plurality of threaded grooves 24, a movable groove 27 is provided on the top surface of the placing table 16, movable holes 28 are respectively provided on the left and right sides of the placing table 16, two clamping plates 29 are movably provided inside the movable groove 27, third electric push rods 30 are respectively fixed on the left and right sides of the placing table 16, and one end of the telescopic rods of the two third electric push rods 30 are respectively fixedly connected with the outer sides of the two clamping plates 29.

[0039] In use, when the printing box 8 moves, it can drive the scraper 23 to move, and then can scrape the solder paste on the printing plate 18, squeeze the solder paste to the surface of the circuit board, complete the printing of the circuit board, and achieve uniform application of the solder paste. The use of the threaded groove 24 and the bolt 26 is convenient for the staff to disassemble and assemble the scraper 23, and then it is convenient for the staff to clean or replace the scraper 23. After the staff places the circuit board on the top surface of the placement table 16, by starting the third electric push rod 30, the two clamping plates 29 are close to each other, and the circuit board can be clamped and fixed, ensuring the stability of the circuit board during the printing process and preventing the printing quality from being reduced due to the movement of the circuit board.

[0040] like Figure 1 , Figure 2 , Figure 6 and Figure 7 As shown, connecting grooves 31 are respectively opened on the inner sides of the two fixed plates 1, and fourth electric push rods 32 are respectively fixed inside the two connecting grooves 31. One end of the telescopic rods of the two fourth electric push rods 32 are respectively fixedly connected to the outer sides of the two L-shaped frames 17, and a plurality of fifth electric push rods 33 are respectively fixed on the inner sides of the two L-shaped frames 17. A measuring rod 34 is fixed between the two fixed plates 1, and a scale 35 is provided on the front side of the measuring rod 34. Measuring plates 36 are respectively fixed to the top surfaces of the two L-shaped frames 17.

[0041] In use, the L-shaped frame 17 can be moved left and right by starting the fourth electric push rod 32, so that the staff can adjust the distance between the two L-shaped frames 17, and can place printing plates 18 of different sizes, thereby improving the flexibility and practicality of the device. After the staff places the printing plate 18 between the two L-shaped frames 17, the fifth electric push rod 33 is started so that one end of its telescopic rod contacts the top surface of the printing plate 18, and the printing plate 18 is pressed and fixed, thereby ensuring the stability of the printing plate 18 during the printing process and preventing the printing quality from being reduced due to the movement of the printing plate 18. When adjusting the distance between the two L-shaped frames 17, the staff can accurately measure the distance between the two L-shaped frames 17 by observing the movement of the measuring plate 36 in front of the measuring rod 34 and the scale value on the scale 35, which not only provides intuitive measurement data, but also ensures the accuracy of the distance between the L-shaped frames 17.

[0042] The present invention also provides a reprinting process for defective circuit boards, comprising the following steps:

[0043] S1: The staff first connects the feed pipe 9 to the solder paste storage device (not shown in the figure), and injects a proper amount of solder paste into the printing box 8 through the first delivery pump 10. Then the staff activates the fourth electric push rod 32 to enable the L-shaped frame 17 to move left and right, adjusts the distance between the two L-shaped frames 17, and then places the printed board 18 on the two L-shaped frames 17. Then, the staff activates the fifth electric push rod 33, so that one end of its telescopic rod contacts the top surface of the printed board 18, and presses and fixes the printed board 18. Then, the staff places the defective circuit board on the top surface of the placement table 16;

[0044] S2: After the circuit board is placed, the staff starts the second electric push rod 15 to make the placement table 16 and the circuit board rise until the circuit board fits with the bottom surface of the printed board 18, and starts the second guide rail 20 to make the slider move forward and backward, thereby driving the moving plate 21 and the CCD camera 22 to move forward and backward. When the CCD camera 22 moves to the top of the circuit board, it automatically takes an image of the circuit board and transmits the data to the automatic optical detector 19;

[0045] S3: After receiving the data, the automatic optical detector 19 uses an image processing algorithm to quickly identify the location where the solder paste is missing on the circuit board, and feeds back the location information of the defective area to the PLC controller. Based on this information, the PLC controller controls the first guide rail 4 to automatically move the fixing frame 5 and the printing box 8 to the defective area.

[0046] S4: The PLC controller controls the first electric push rod 6 to make the connecting frame 7 and the printing box 8 descend to the top surface of the printing board 18, and then starts the second delivery pump 13 on the discharge pipe 12 corresponding to the position where the solder paste on the circuit board is missing, squeezes the solder paste in the printing box 8, enters the printing hole of the printing board 18 through the discharge pipe 12, and squeezes the solder paste to the position where the solder paste on the circuit board is missing;

[0047] S5: When the printing box 8 moves, it can drive the scraper 23 to move, and then can scrape the solder paste on the printing board 18, squeeze the solder paste to the surface of the circuit board, and complete the printing work on the circuit board.

[0048] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A reprinting device for defective circuit boards, comprising two fixing plates (1), wherein the two fixing plates (1) are respectively fixed on the top surface of a workbench (2), and characterized in that: A fixing groove (3) is respectively provided on the inner side of the two fixing plates (1), a PLC controller is fixed on the front side of the workbench (2), a first guide rail (4) is respectively fixed inside the two fixing grooves (3), the first guide rail (4) is electrically connected to the PLC controller, a fixing frame (5) is fixed between the sliders of the two first guide rails (4), a first electric push rod (6) is fixed on the inner top surface of the fixing frame (5), the first electric push rod (6) is electrically connected to the PLC controller, a connecting frame (7) is fixed on one end of the telescopic rod of the first electric push rod (6), a printing box (8) is fixed on the bottom surface of the connecting frame (7), the top surface of the printing box (8) is connected to a fixed feed pipe (9), a first delivery pump (10) is provided on the feed pipe (9), the first delivery pump (10) is electrically connected to the PLC controller The bottom surface of the printing box (8) is provided with a plurality of discharge holes (11), and discharge pipes (12) are fixed inside the plurality of discharge holes (11), and second delivery pumps (13) are provided on the plurality of discharge pipes (12), and the second delivery pumps (13) are electrically connected to the PLC controller; the top surface of the workbench (2) is provided with a mounting groove (14), and a second electric push rod (15) is fixed inside the mounting groove (14), and the second electric push rod (15) is electrically connected to the PLC controller; a placement table (16) is fixed to one end of the telescopic rod of the second electric push rod (15); two L-shaped frames (17) are movably provided above the workbench (2), and a printing plate (18) is provided between the two L-shaped frames (17), and a plurality of printing holes are provided on the top surface of the printing plate (18).

2. A reprinting device for defective circuit boards according to claim 1, characterized in that: An automatic optical detector (19) is fixed on the right side of the workbench (2), and the automatic optical detector (19) is electrically connected to a PLC controller. Second guide rails (20) are respectively fixed on the inner sides of the two fixed plates (1), and a movable plate (21) is fixed between the sliders of the two second guide rails (20). A CCD camera (22) is fixed on the bottom surface of the movable plate (21), and the CCD camera (22) is electrically connected to the PLC controller.

3. A reprinting device for defective circuit boards according to claim 2, characterized in that: A scraper (23) is detachably provided on the front side of the outer wall of the printing box (8).

4. A reprinting device for defective circuit boards according to claim 3, characterized in that: The front side of the outer wall of the printing box (8) is provided with a plurality of threaded grooves (24), the front side of the scraper (23) is provided with a plurality of threaded holes (25), the plurality of threaded holes (25) are respectively threadedly connected with bolts (26), and the threaded ends of the plurality of bolts (26) are respectively threadedly connected with the inner parts of the plurality of threaded grooves (24).

5. A reprinting device for defective circuit boards according to claim 4, characterized in that: A movable groove (27) is provided on the top surface of the placing platform (16), and movable holes (28) are respectively provided on the left and right sides of the placing platform (16). Two clamping plates (29) are movably provided inside the movable groove (27), and third electric push rods (30) are respectively fixed on the left and right sides of the placing platform (16), and one end of the telescopic rods of the two third electric push rods (30) is respectively fixedly connected to the outer sides of the two clamping plates (29).

6. A reprinting device for defective circuit boards according to claim 5, characterized in that: The inner sides of the two fixing plates (1) are respectively provided with connection grooves (31), and the insides of the two connection grooves (31) are respectively fixed with fourth electric push rods (32), and one end of the telescopic rods of the two fourth electric push rods (32) is respectively fixedly connected to the outer sides of the two L-shaped frames (17).

7. The reprinting device for defective circuit boards according to claim 1, characterized in that: A plurality of fifth electric push rods (33) are respectively fixed on the inner sides of the two L-shaped frames (17).

8. The reprinting device for defective circuit boards according to claim 7, characterized in that: A measuring rod (34) is fixed between the two fixing plates (1), a scale (35) is provided on the front side of the measuring rod (34), and measuring plates (36) are respectively fixed on the top surfaces of the two L-shaped frames (17).

9. A reprinting process for defective circuit boards, characterized in that: The steps include: S1: The staff first connects the feed pipe (9) to the solder paste storage device, and injects a proper amount of solder paste into the printing box (8) through the first delivery pump (10). Then, the staff activates the fourth electric push rod (32) to enable the L-shaped frame (17) to move left and right, adjusts the distance between the two L-shaped frames (17), and then places the printing plate (18) on the two L-shaped frames (17). Then, the staff activates the fifth electric push rod (33) so that one end of its telescopic rod contacts the top surface of the printing plate (18), and presses and fixes the printing plate (18). Then, the staff places the defective circuit board on the top surface of the placement table (16); S2: After the placement of the circuit board is completed, the staff starts the second electric push rod (15) to make the placement table (16) and the circuit board rise until the circuit board is in contact with the bottom surface of the printed board (18), and starts the second guide rail (20) to make the slider move forward and backward, thereby driving the moving plate (21) and the CCD camera (22) to move forward and backward. When the CCD camera (22) moves to the top of the circuit board, it automatically captures the image of the circuit board and transmits the data to the automatic optical detector (19); S3: After receiving the data, the automatic optical detector (19) uses an image processing algorithm to quickly identify the location where the solder paste is missing on the circuit board, and feeds back the location information of the defective area to the PLC controller. Based on the information, the PLC controller controls the first guide rail (4) so ​​that the fixing frame (5) and the printing box (8) are automatically moved to the defective area. S4: The PLC controller controls the first electric push rod (6) to make the connecting frame (7) and the printing box (8) descend to the top surface of the printing board (18), and then starts the second delivery pump (13) on the discharge pipe (12) corresponding to the position where the solder paste on the circuit board is missing, squeezes the solder paste in the printing box (8) through the discharge pipe (12) into the printing hole of the printing board (18), and squeezes the solder paste to the position where the solder paste on the circuit board is missing; S5: When the printing box (8) moves, it can drive the scraper (23) to move, thereby scraping the solder paste on the printing plate (18), squeezing the solder paste to the surface of the circuit board, and completing the printing work on the circuit board.

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