A method for controlling a back drill stub using PI material

Abstract

This invention provides a method for controlling back-drill stubs using PI material. The method includes the following steps: S1: Precise bonding pretreatment of inner layer PI; S2: Multilayer board lamination and pressing; S3: Through-hole drilling; S4: Through-hole copper plating; S5: Electroplating thickening of the entire board circuit; S6: Reflow soldering and high-temperature curing; S7: Ultrasonic immersion cleaning for copper removal and finishing. This invention provides a method for controlling back-drill stubs using PI material, which reduces the need for back-drilling processes, saves board area, allows for better routing, and facilitates control over back-drill stub values, especially for high-multilayer server PCBs where stub requirements are strict and processing is difficult.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board processing and manufacturing technology, and in particular to a method for controlling back-drilling stubs using PI material. Background Technology

[0002] On multilayer printed circuit boards, signal transmission between layers is achieved through metallized vias. To ensure signal conduction between specific layers, a back-drilling process is often used to remove the metal from the via wall, selectively severing layers that do not require connection or transmission. This process involves using a drill bit larger than the via diameter to perform controlled-depth drilling at the original via location, removing the metal (copper) from the via wall connecting non-designated layers. This allows the remaining metal from the via wall to achieve localized circuit conduction between layers, thereby avoiding reflection, scattering, and delay in high-speed signal transmission, which can cause signal distortion.

[0003] As PCBs develop towards higher layers, greater thickness, higher frequency, and higher speed, the depth control requirements are also increasing. Due to the influence of multiple factors such as board thickness uniformity and depth control capability, the stub value after back drilling is difficult to meet the requirements, resulting in reflection, scattering, and delay in high-speed signal transmission, causing signal "distortion". To meet the high requirements of back drilling stub, PCB manufacturers need to purchase CCD back drilling machines, which will greatly increase costs.

[0004] Existing back-drilling methods are costly, PTFE materials are expensive, and the stub value after back-drilling is difficult to meet requirements, resulting in reflection, scattering, and delay in high-speed signal transmission, causing signal "distortion".

[0005] Therefore, it is necessary to provide a method for controlling the back drill stub using PI material to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides a method for controlling the back-drilling stub using PI material, which solves the problems of high cost, high price of PTFE material, and difficulty in meeting the requirements of the stub value after back-drilling in the existing back-drilling method, which causes reflection, scattering and delay in high-speed signal transmission, resulting in signal "distortion".

[0007] To solve the above-mentioned technical problems, the present invention provides a method for controlling a back drill stub using PI material, comprising the following steps: S1: Precise bonding pretreatment of inner layer PI; Positioning the non-drillable inner layer corresponding to all back drill holes inside the multi-layer PCB board. During the inner layer material preparation stage, cut PI film material of the corresponding size, and completely bond and fix the PI material to the preset position of the non-drillable inner layer corresponding to each back drill hole, completely covering the vertical projection area of ​​the back drill hole. S2: Multilayer board lamination and pressing; After all inner layer PI materials are bonded and fixed, the inner core board with PI material, PP prepreg, and surface board are precisely laminated and aligned according to the conventional multilayer PCB production process. The entire board is pressed by high temperature and high pressure pressing equipment, so that the inner layer structure, PI material, PP material, and core board are completely fused and solidified into a whole multilayer PCB substrate. The PI material is permanently fixed in the preset non-drillable inner layer position. S3: Through-hole drilling; For all signal vias in the PCB design, conventional drilling equipment is used to perform a unified drilling operation on the press-fitted PCB, drilling through all layers of the board to form a complete through-hole that runs through the upper and lower surfaces, retaining the conventional through-hole structure, without the need for targeted depth control drilling or back drilling allowance. S4: Through-hole copper plating treatment; A conventional chemical copper plating process is performed on the entire PCB board after drilling, in which a thin copper layer is deposited on the surface of the hole wall of all through holes by copper plating solution, so as to achieve the initial conductivity of the through hole wall. S5: Thickened electroplating of the entire circuit board; The PCB after copper plating is subjected to overall copper plating thickening treatment, and the copper plating layer on the wall of the through hole is thickened and solidified to form a stable conductive copper wall. S6: Reflow soldering high-temperature curing treatment; After electroplating, the entire PCB board undergoes reflow soldering high-temperature treatment. S7: Ultrasonic immersion cleaning for copper removal and finishing; The PCB after reflow soldering is put into an ultrasonic immersion cleaning equipment, and the inside of the through holes and the corresponding hole wall of the PI material are deeply cleaned by high-frequency ultrasonic vibration and special cleaning solution.

[0008] Preferably, in step S3 of the method for controlling the back drill stub using PI material, drilling equipment is required during the drilling process, and the drilling equipment includes: a worktable; The track is located on the rear side of the top of the workbench. A movable component is slidably mounted on the surface of the track. A lifting component is fixedly mounted on the top of the movable component. A fixed plate is fixedly mounted on the top of the output shaft of the lifting component. A driving component is fixedly installed on the front side of the top of the fixed plate, and a connecting column is fixedly installed on the front side of the bottom of the fixed plate. A drill rod mounting nozzle is rotatably installed on the bottom of the connecting column. A folding device is fixedly installed at the bottom of the outer surface of the connecting column. The folding device includes a fixed ring block, a sliding rod, a stop block, a movable ring block, and an elastic element. The fixed ring block is fixedly installed at the bottom of the outer surface of the connecting column. Multiple sliding rods are slidably installed around the inside of the fixed ring block. The stop block is fixedly installed at the top of the sliding rod. The movable ring block is fixedly installed at the bottom of the sliding rod. The elastic element is sleeved on the outer surface of the sliding rod. A shielding cloth is provided on the top outer surface of the movable ring block. The top of the shielding cloth is fixedly connected to the bottom outer surface of the fixed ring block. A filter box is fixedly installed on the rear side of the top of the fixed plate. An air pipe is fixedly installed on the front side of the filter box, and a fan is fixedly installed on the rear side of the filter box.

[0009] Preferably, one end of the trachea extends to the bottom of the fixing ring block.

[0010] Preferably, a mounting platform is fixedly installed on the front side of the top of the workbench, and a moving groove is provided on both sides of the middle of the top of the fixed platform.

[0011] Preferably, a threaded screw is rotatably mounted in the middle of the moving groove, and an adjusting block is fixedly mounted at one end of the threaded screw.

[0012] Preferably, the outer surface of the threaded screw is threaded with a clamping plate.

[0013] Preferably, the clamping plate is slidably mounted inside the movable groove.

[0014] Preferably, the top of the filter box has a slot in the middle, a collection device is provided inside the slot, and a connecting plate is fixedly installed on the top of the collection device.

[0015] Preferably, the collection device includes a collection box, a collection trough, a connecting hole, and a filter hole. The collection box is disposed inside the opening trough, the collection trough is opened in the middle of the inside of the collection box, the multiple connecting holes are respectively opened on one side of the outer surface of the collection box, and the multiple filter holes are respectively opened on the other side of the outer surface of the collection box.

[0016] Preferably, a tie rod is fixedly installed at the top center of the connecting plate.

[0017] Compared with related technologies, the method for controlling the back drill stub using PI material provided by the present invention has the following advantages: This invention provides a method for controlling back-drilling stubs using PI material. This method eliminates the need for back-drilling, saves board area, and allows for better routing. The stub value is controllable, and PI is bonded to non-drillable layers, even achieving zero stubs. Compared to the original PTFE solution, PI material is cheaper. PI material has a higher yield and will not fall off after being bonded to the board. The PP in the PI material process does not require processing, making the process more advantageous and easier to control the back-drilling stub value, especially for high-multilayer server PCBs, which have strict stub requirements and are difficult to process. Attached Figure Description

[0018] Figure 1 A flowchart of a method for controlling a back drill stub using PI material, provided by the present invention; Figure 2 A schematic flowchart illustrating a method for controlling a back drill stub using PI material, provided by the present invention. Figure 3 A schematic diagram of the second embodiment of a drilling device for a method of controlling a back drill stub using PI material provided by the present invention. Figure 4 for Figure 1 The diagram shows the structure of the folding device. Figure 5 for Figure 3 A rear view of the collection box shown; Figure 6 A schematic diagram of the third embodiment of a drilling device for a method of controlling a back drill stub using PI material provided by the present invention; Figure 7 for Figure 6 A cross-sectional schematic diagram of the collection device shown.

[0019] The following are the labels in the diagram: 1. Workbench, 2. Track, 3. Moving part, 4. Lifting part, 5. Fixed plate, 6. Filter box, 7. Air pipe, 8. Fan, 9. Drive component, 10. Connecting column, 11. Drill rod mounting nozzle, 12. Folding device, 121. Fixed ring block, 122. Slide rod, 123. Stop block, 124. Moving ring block, 125. Elastic component, 13. Shielding cloth, 14. Mounting platform, 15. Moving groove, 16. Threaded screw, 17. Adjusting block, 18. Clamping plate, 19. Opening groove, 20. Connecting plate, 21. Collection device, 211. Collection box, 212. Collection groove, 213. Connecting hole, 214. Filter hole, 22. Pull rod. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] First embodiment: Please refer to the following: Figure 1 and Figure 2 ,in, Figure 1 A flowchart of a method for controlling a back drill stub using PI material, provided by the present invention; Figure 2 This is a flowchart illustrating a method for controlling a back drill stub using PI material, as provided by the present invention.

[0022] A method for controlling a back drill stub using PI material includes the following steps: S1: Precise bonding pretreatment of inner layer PI; Positioning the non-drillable inner layer corresponding to all back drill holes inside the multi-layer PCB board. During the inner layer material preparation stage, cut PI film material of the corresponding size, and completely bond and fix the PI material to the preset position of the non-drillable inner layer corresponding to each back drill hole, completely covering the vertical projection area of ​​the back drill hole. S2: Multilayer board lamination and pressing; After all inner layer PI materials are bonded and fixed, the inner core board with PI material, PP prepreg, and surface board are precisely laminated and aligned according to the conventional multilayer PCB production process. The entire board is pressed by high temperature and high pressure pressing equipment, so that the inner layer structure, PI material, PP material, and core board are completely fused and solidified into a whole multilayer PCB substrate. The PI material is permanently fixed in the preset non-drillable inner layer position. S3: Through-hole drilling; For all signal vias in the PCB design, conventional drilling equipment is used to perform a unified drilling operation on the press-fitted PCB, drilling through all layers of the board to form a complete through-hole that runs through the upper and lower surfaces, retaining the conventional through-hole structure, without the need for targeted depth control drilling or back drilling allowance. S4: Through-hole copper plating treatment; A conventional chemical copper plating process is performed on the entire PCB board after drilling, in which a thin copper layer is deposited on the surface of the hole wall of all through holes by copper plating solution, so as to achieve the initial conductivity of the through hole wall. S5: Thickened electroplating of the entire circuit board; The PCB after copper plating is subjected to overall copper plating thickening treatment, and the copper plating layer on the wall of the through hole is thickened and solidified to form a stable conductive copper wall. S6: Reflow soldering high-temperature curing treatment; After electroplating, the entire PCB board undergoes reflow soldering high-temperature treatment. S7: Ultrasonic immersion cleaning for copper removal and finishing; The PCB after reflow soldering is put into an ultrasonic immersion cleaning equipment, and the inside of the through holes and the corresponding hole wall of the PI material are deeply cleaned by high-frequency ultrasonic vibration and special cleaning solution.

[0023] Compared with related technologies, the method for controlling the back drill stub using PI material provided by the present invention has the following advantages: This invention provides a method for controlling back-drilling stubs using PI material. This method eliminates the need for back-drilling, saves board area, and allows for better routing. The stub value is controllable, and PI is bonded to non-drillable layers, even achieving zero stubs. Compared to the original PTFE solution, PI material is cheaper. PI material has a higher yield and will not fall off after being bonded to the board. The PP in the PI material process does not require processing, making the process more advantageous and easier to control the back-drilling stub value, especially for high-multilayer server PCBs, which have strict stub requirements and are difficult to process.

[0024] Second embodiment: Please refer to the following: Figure 3 , Figure 4 and Figure 5 Based on the first embodiment of this application, which provides a method for controlling a back drill stub using PI material, the second embodiment of this application proposes another method for controlling a back drill stub using PI material. The second embodiment is merely a preferred embodiment of the first embodiment, and its implementation will not affect the independent implementation of the first embodiment.

[0025] Specifically, the difference in the second embodiment of this application regarding the operation method of controlling a back drill stub using PI material is that drilling equipment is required during the drilling process in step S3 of the operation method of controlling a back drill stub using PI material. The drilling equipment includes: a worktable 1. Track 2 is located on the rear side of the top of the workbench 1. A movable part 3 is slidably installed on the surface of the track 2. A lifting part 4 is fixedly installed on the top of the movable part 3. A fixed plate 5 is fixedly installed on the top of the output shaft of the lifting part 4. The driving component 9 is fixedly installed on the front side of the top of the fixed plate 5. A connecting column 10 is fixedly installed on the front side of the bottom of the fixed plate 5. A drill rod mounting nozzle 11 is rotatably installed on the bottom of the connecting column 10. A folding device 12 is fixedly installed at the bottom of the outer surface of the connecting column 10. The folding device 12 includes a fixed ring block 121, a sliding rod 122, a stop block 123, a movable ring block 124, and an elastic element 125. The fixed ring block 121 is fixedly installed at the bottom of the outer surface of the connecting column 10. Multiple sliding rods 122 are slidably installed around the inside of the fixed ring block 121. The stop block 123 is fixedly installed at the top of the sliding rod 122. The movable ring block 124 is fixedly installed at the bottom of the sliding rod 122. The elastic element 125 is sleeved on the outer surface of the sliding rod 122. A shielding cloth 13 is provided on the top outer surface of the movable ring block 124. The top of the shielding cloth 13 is fixedly connected to the bottom outer surface of the fixed ring block 121. The filter box 6 is fixedly installed on the rear side of the top of the fixing plate 5. An air pipe 7 is fixedly installed on the front side of the filter box 6, and a fan 8 is fixedly installed on the rear side of the filter box 6.

[0026] One end of the trachea 7 extends to the bottom of the fixing ring block 121.

[0027] A mounting platform 14 is fixedly installed on the front side of the top of the workbench 1, and a moving groove 15 is provided on both sides of the middle of the top of the fixed platform 14.

[0028] A threaded screw 16 is rotatably mounted in the middle of the moving groove 15, and an adjusting block 17 is fixedly mounted on one end of the threaded screw 16.

[0029] The outer surface of the threaded screw 16 is threaded with a clamping plate 18.

[0030] The clamping plate 18 is slidably installed inside the moving groove 15.

[0031] Track 2 can be an electromagnetic track or a threaded screw. The threaded engagement moving part 3 can slide left and right. The electromagnetic engagement moving part 3 of the electromagnetic track can also slide due to magnetic force, which is an existing sliding technology.

[0032] The lifting component 4 is an electric telescopic rod or a hydraulic cylinder device used to control the up and down movement of the fixed plate 5.

[0033] The fan 8 is existing technology. The surface of the fan 8 is provided with connecting grooves on the left and right sides. The filter box 6 is also provided with ventilation grooves on the side near the fan 8, so that the airflow can enter the filter box 6 from the air pipe 7 and be discharged by the fan 8. The negative pressure intensity of the airflow can attract the debris and make it flow with the airflow.

[0034] The drive unit 9 is a servo motor device. The bottom end of the output shaft of the drive unit 9 is fixedly connected to the drill rod mounting base 11. The drill rod can be installed at the bottom of the drill rod mounting base 11 to install drilling equipment on the existing drill rod.

[0035] The connecting column 10 is fixed to the bottom of the fixing plate 5 and does not move.

[0036] The top of the fixed ring block 121 is provided with sliding holes around its four sides, through which the sliding rods 122 extend to the top of the fixed ring block 121 and connect to the stop block 123. The diameter of the stop block 123 is larger than that of the sliding hole, so that when the moving ring block 124 is subjected to an upward compressive force, the moving ring block 124 drives the four sliding rods 122 to move upward. The sliding rods 122 slide upward along the sliding hole, and the stop block 123 plays a limiting role to prevent the sliding rods 122 from falling off the fixed ring block 121.

[0037] The elastic element 125 is a spring device. The elastic element 125 is sleeved on the outer surface of the slide rod 122. The top end of the elastic element 125 is connected to the bottom of the fixed ring block 121, and the bottom end of the elastic element 125 is connected to the top of the movable ring block 124. The restoring force of the elastic element 125 pushes the movable ring block 124 downward, so that the stop block 123 is restricted to the top surface of the fixed ring block 121. When the movable ring block 124 is not under pressure, the restoring force of the elastic element 125 pushes the movable ring block 124 downward away from the fixed ring block 121, so that the covering cloth 13 between the movable ring block 124 and the fixed ring block 121 unfolds.

[0038] The clamping plate 18 has threaded holes on its surface, which are threaded into the outer surface of the threaded screw 16. The two clamping plates 18 work together to clamp and fix PCBs of different sizes, improving the adaptability of the device to PCBs of different specifications. The clamping plates 18 are also fixed stably, preventing the PCBs from shifting during drilling and affecting the drilling accuracy, thus improving the stability and processing accuracy of the drilling operation.

[0039] The working principle of the method for controlling the back drill stub using PI material provided by this invention is as follows: During operation, the output shaft of the lifting component 4 moves downward, pulling the fixing plate 5 downward. The fixing plate 5 drives the connecting column 10 and the drill rod mounting nozzle 11 to move downward, so that the drill rod at the bottom of the drill rod mounting nozzle 11 slowly approaches the PCB board and performs drilling. The bottom of the moving ring block 124 is attached to the surface of the PCB board, and the drilling position of the drill rod is covered by the shielding cloth 13 to shield the flying debris.

[0040] At the same time, the blower 8 starts, and the airflow is drawn into the filter box 6 through the air pipe 7 and discharged from the blower 8, so that the air pipe 7 absorbs the debris raised at the drilling position of the covered drill rod into the filter box 6.

[0041] During drilling, as the bottom end of the drill rod penetrates deeper into the PCB board, the movable ring block 124 adheres to the surface of the PCB board. As the drill rod penetrates deeper, the movable ring block 124 presses against the PCB board and pushes the slide rod 122 upward. The slide rod 122 slides upward along the fixed ring block 121 and presses against the elastic element 126, reducing the gap between the movable ring block 124 and the fixed ring block 121. The drill rod drills deeper and deeper, and the shielding cloth 13 is folded, which does not affect the drilling and protects and absorbs the debris raised during drilling.

[0042] Compared with related technologies, the method for controlling the back drill stub using PI material provided by the present invention has the following advantages: This invention provides a method for controlling a back drill stub using PI material. The drilling position is shielded by a folding device 12, and the blower 8 absorbs debris to prevent debris generated during drilling from splashing into the air and affecting the working environment and the health of the operators. The shielding cloth 13 can automatically fold and retract as the drill rod moves down, without hindering normal drilling operations.

[0043] Third embodiment: Please refer to the following: Figure 6 and Figure 7 Based on the first embodiment of this application, which provides a method for controlling a back drill stub using PI material, the second embodiment of this application proposes another method for controlling a back drill stub using PI material. The second embodiment is merely a preferred embodiment of the first embodiment, and its implementation will not affect the independent implementation of the first embodiment.

[0044] Specifically, the second embodiment of this application provides a different method for controlling the back drill stub using PI material, wherein the filter box 6 has a slot 19 in the middle of its top, a collection device 21 is provided inside the slot 19, and a connecting plate 20 is fixedly installed on the top of the collection device 21.

[0045] The collection device 21 includes a collection box 211, a collection groove 212, a connecting hole 213, and a filter hole 214. The collection box 211 is disposed inside the slot 19. The collection groove 212 is opened in the middle of the inside of the collection box 211. A plurality of connecting holes 213 are respectively opened on one side of the outer surface of the collection box 211, and a plurality of filter holes 214 are respectively opened on the other side of the outer surface of the collection box 211.

[0046] A pull rod 22 is fixedly installed at the top center of the connecting plate 20.

[0047] The diameter of the connecting hole 213 is larger than that of the filter hole 214.

[0048] The working principle of the method for controlling the back drill stub using PI material provided by this invention is as follows: During operation, the collection box 211 is first placed inside the slot 19, and the connecting plate 20 is attached to the top surface of the filter box 6.

[0049] The airflow generated by the fan 8 enters the interior of the slot 19 through the air pipe 7. The debris in the airflow enters the filter box 6 and enters the collection tank 212 through the connecting hole 213. It is intercepted and stored in the collection tank 212 by the filter hole 214, while the airflow is discharged through the filter hole 214.

[0050] When cleaning is needed, the user can simply hold the lever 22 to lift the collection box 211 upwards, and then pour out the debris through the connecting hole 213.

[0051] Compared with related technologies, the method for controlling the back drill stub using PI material provided by the present invention has the following advantages: This invention provides a method for controlling a back drill stub using PI material. The collection device 21 collects and stores the debris generated during drilling, making it convenient for users to clean up the debris in a unified manner. The collection box 211 can be pulled out and emptied at any time, and the debris cleaning operation can be completed without disassembling the device, which simplifies the debris cleaning steps and improves the cleaning efficiency.

[0052] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for controlling a back drill stub using PI material, characterized in that, Includes the following steps: S1: Precise bonding pretreatment of inner layer PI; Positioning the non-drillable inner layer corresponding to all back drill holes inside the multi-layer PCB board. During the inner layer material preparation stage, cut PI film material of the corresponding size, and completely bond and fix the PI material to the preset position of the non-drillable inner layer corresponding to each back drill hole, completely covering the vertical projection area of ​​the back drill hole. S2: Multilayer board lamination and pressing; After all inner layer PI materials are bonded and fixed, the inner core board with PI material, PP prepreg, and surface board are precisely laminated and aligned according to the conventional multilayer PCB production process. The entire board is pressed by high temperature and high pressure pressing equipment, so that the inner layer structure, PI material, PP material, and core board are completely fused and solidified into a whole multilayer PCB substrate. The PI material is permanently fixed in the preset non-drillable inner layer position. S3: Through-hole drilling; For all signal vias in the PCB design, conventional drilling equipment is used to perform a unified drilling operation on the press-fitted PCB, drilling through all layers of the board to form a complete through-hole that runs through the upper and lower surfaces, retaining the conventional through-hole structure, without the need for targeted depth control drilling or back drilling allowance. S4: Through-hole copper plating treatment; A conventional chemical copper plating process is performed on the entire PCB board after drilling, in which a thin copper layer is deposited on the surface of the hole wall of all through holes by copper plating solution, so as to achieve the initial conductivity of the through hole wall. S5: Thickened electroplating of the entire circuit board; The PCB after copper plating is subjected to overall copper plating thickening treatment, and the copper plating layer on the wall of the through hole is thickened and solidified to form a stable conductive copper wall. S6: Reflow soldering high-temperature curing treatment; After electroplating, the entire PCB board undergoes reflow soldering high-temperature treatment. S7: Ultrasonic immersion cleaning for copper removal and finishing; The PCB after reflow soldering is put into an ultrasonic immersion cleaning equipment, and the inside of the through holes and the corresponding hole wall of the PI material are deeply cleaned by high-frequency ultrasonic vibration and special cleaning solution.

2. The method for controlling a back drill stub using PI material according to claim 1, characterized in that, In step S3 of the method for controlling the back drill stub using PI material, drilling equipment is required during the drilling process. The drilling equipment includes a worktable. The track is located on the rear side of the top of the workbench. A movable component is slidably mounted on the surface of the track. A lifting component is fixedly mounted on the top of the movable component. A fixed plate is fixedly mounted on the top of the output shaft of the lifting component. A driving component is fixedly installed on the front side of the top of the fixed plate, and a connecting column is fixedly installed on the front side of the bottom of the fixed plate. A drill rod mounting nozzle is rotatably installed on the bottom of the connecting column. A folding device is fixedly installed at the bottom of the outer surface of the connecting column. The folding device includes a fixed ring block, a sliding rod, a stop block, a movable ring block, and an elastic element. The fixed ring block is fixedly installed at the bottom of the outer surface of the connecting column. Multiple sliding rods are slidably installed around the inside of the fixed ring block. The stop block is fixedly installed at the top of the sliding rod. The movable ring block is fixedly installed at the bottom of the sliding rod. The elastic element is sleeved on the outer surface of the sliding rod. A shielding cloth is provided on the top outer surface of the movable ring block. The top of the shielding cloth is fixedly connected to the bottom outer surface of the fixed ring block. A filter box is fixedly installed on the rear side of the top of the fixed plate. An air pipe is fixedly installed on the front side of the filter box, and a fan is fixedly installed on the rear side of the filter box.

3. The method for controlling a back drill stub using PI material according to claim 2, characterized in that, One end of the trachea extends to the bottom of the fixed ring block.

4. The method for controlling a back drill stub using PI material according to claim 2, characterized in that, A mounting platform is fixedly installed on the front side of the top of the workbench, and a moving groove is opened on both sides of the middle of the top of the fixed platform.

5. The method for controlling a back drill stub using PI material according to claim 4, characterized in that, A threaded screw is rotatably mounted in the middle of the moving groove, and an adjusting block is fixedly mounted at one end of the threaded screw.

6. The method for controlling a back drill stub using PI material according to claim 5, characterized in that, The outer surface of the threaded screw is threaded with a clamping plate.

7. A method for controlling a back drill stub using PI material according to claim 6, characterized in that, The clamping plate is slidably installed inside the moving slot.

8. The method for controlling a back drill stub using PI material according to claim 2, characterized in that, The filter box has a slot in the middle of its top, and a collection device is installed inside the slot. A connecting plate is fixedly installed on the top of the collection device.

9. A method for controlling a back drill stub using PI material according to claim 8, characterized in that, The collection device includes a collection box, a collection trough, a connecting hole, and a filter hole. The collection box is disposed inside the opening trough, the collection trough is opened in the middle of the inside of the collection box, the multiple connecting holes are respectively opened on one side of the outer surface of the collection box, and the multiple filter holes are respectively opened on the other side of the outer surface of the collection box.

10. A method for controlling a back drill stub using PI material according to claim 8, characterized in that, A tie rod is fixedly installed at the top center of the connecting plate.

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