Multi-layer circuit board back drilling process and drilling equipment thereof
Through the vertical sliding structure and hollow layout formed by the fixed seat and the slide, the drill bit and the suction tube move synchronously, which solves the problems of hole alignment and debris removal during back drilling of multi-layer circuit boards, and achieves high-precision machining and reliable electrical performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-26
- Publication Date
- 2026-03-24
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing back-drilling equipment cannot simultaneously guarantee hole alignment accuracy and timely debris removal in multilayer circuit board processing, resulting in misaligned holes, blocked holes, and scratches on the hole walls, which affects electrical performance reliability, especially in high-density interconnect or multilayer thick board scenarios.
It adopts a vertical sliding structure consisting of a fixed seat, a middle slide and a top slide, and a hollow layout. The drill bit and suction tube move synchronously, and the debris is removed in time through gravity and negative pressure adsorption, ensuring accurate hole centering.
It achieves precise hole alignment and instant debris adsorption during the back drilling process of circuit boards, avoiding hole deviation, hole blockage and debris residue, and improving processing quality and electrical performance reliability.
Smart Images
Figure CN121728680A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of back drilling technology for circuit boards, and more particularly to a back drilling process and drilling equipment for multilayer circuit boards. Background Technology
[0002] In the design of high-speed, high-frequency signal transmission on multilayer circuit boards, to reduce signal reflection and stub effect, back-drilling is required on multilayer boards with completed through-hole plating. This involves drilling the existing through-holes from one side of the board to remove excess copper pillars that are not connected to the signal layer. This process requires highly precise drilling positions and ensures that no copper chips or dielectric debris generated during drilling remain inside the holes.
[0003] Existing back-drilling equipment typically separates the positioning mechanism from the drilling mechanism. During drilling, chip removal relies on gravity or suction from above the board surface. However, the PCB clamping platform is often a solid structure without a pre-designed chip removal channel. Since the drilling position needs to be aligned via a sliding table, the table itself obstructs the bottom of the through-hole, making it impossible to place a chip suction port directly below the hole. Even with lateral suction, the long airflow path and skewed direction make it difficult to effectively capture fine copper chips. This makes it difficult for existing technologies to simultaneously guarantee hole alignment accuracy and timely chip removal during back-drilling. This can easily lead to misaligned holes due to positioning errors, or through-hole blockage and hole wall scratches due to chip accumulation, affecting subsequent electrical performance reliability, especially in high-density interconnect or multi-layer thick board scenarios. Summary of the Invention
[0004] The purpose of this invention is to provide a back-drilling process and drilling equipment for multilayer circuit boards to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: A multilayer circuit board drilling device includes a base, a panel fixedly mounted on the top of the base, a positioning component above the panel, the positioning component including a fixed seat fixedly mounted on the panel, a middle slide seat slidably mounted above the fixed seat, a top slide seat slidably mounted above the middle slide seat, the middle slide seat and the top slide seat slide perpendicularly to each other above the fixed seat, the circuit board is placed on the top slide seat, a drill suction component is provided above the positioning component, the drill suction component includes a drill platform module located directly above the top slide seat, a drill bit is mounted on the bottom of the drill platform module, a suction tube is concentrically mounted below the drill bit, the drill bit and the suction tube move synchronously towards or away from each other.
[0006] Preferably, a drill bit is installed at the bottom of the drill platform module, and the drill bit moves up and down with the drill platform module, while the middle slide and the top slide drive the circuit board to move horizontally.
[0007] Preferably, the middle part of the fixed seat, the middle slide and the top slide are hollow, and the middle part of the top slide has a fixing opening with the edge of the fixing opening being stepped.
[0008] Preferably, uprights are fixedly installed on both sides of the fixed base, and an upper sliding plate is slidably installed between the two uprights. The drilling module is fixedly installed on the side wall of the upper sliding plate. The uprights improve the sliding stability of the upper sliding plate, and the sliding upper sliding plate drives the drilling module to move up and down.
[0009] Preferably, a sliding plate is slidably disposed below the panel, a clamp is fixedly installed on the side wall of the sliding plate, a sleeve rod is fixedly installed on the clamp, the sleeve rod passes through the panel, and a straw is inserted into the top of the sleeve rod.
[0010] Preferably, a double-segment screw is rotatably installed on the side of the upright near the upper slide plate. The double-segment screw has two sections of threads with opposite helical directions. The ends of the upper slide plate and the lower slide plate are respectively connected to the two ends of the double-segment screw through threads. A third closed-loop servo motor is fixedly installed on the top of the upright, and the output shaft of the third closed-loop servo motor is connected to the double-segment screw.
[0011] Preferably, a pair of first sliding sleeves are fixedly installed on both sides of the bottom of the intermediate slide block, and a first optical shaft is rotatably installed on both sides of the top of the fixed seat. The first sliding sleeves are slidably sleeved on the first optical shaft. A first rotating nut seat is fixedly installed on the bottom of the intermediate slide block, and a first screw is rotatably installed on the top of the fixed seat. The first screw is connected to the first rotating nut seat by a thread. A first closed-loop servo motor is fixedly installed on one side of the fixed seat. The top slide block has a second sliding sleeve fixedly installed on both sides of its bottom. The middle slide block has a second optical axis rotatably installed on both sides of its top. The second sliding sleeve is slidably fitted onto the second optical axis. The bottom of the top slide block has a second rotating nut seat fixedly installed. The top of the middle slide block has a second screw rotatably installed. The second screw is connected to the second rotating nut seat by a thread. A second closed-loop servo motor is fixedly installed on one side of the middle slide block. The second optical axis is perpendicular to the first optical axis.
[0012] A back-drilling process for multilayer circuit boards includes the following steps: S1. Place the multilayer circuit board to be processed on the top slide, and use the stepped edge of the fixing port to fix the circuit board in place, so that the circuit board is located between the drill bit and the suction tube. S2. According to the preset drilling coordinates, control the positioning component to work, and use the mutual vertical sliding of the middle slide and the top slide to drive the circuit board to move horizontally, so as to accurately align the center of the through hole to be back drilled on the circuit board to the concentric axis of the drill bit and the suction tube. S3. Start the drill and suction assembly to drive the drill bit and suction tube to move synchronously in opposite directions; that is, the drill bit feeds downwards to approach the upper surface of the circuit board, while the suction tube moves upwards through the hollow areas of the fixed seat, the middle slide and the top slide until the top of the suction tube is inserted into the through hole. S4. The drill bit performs back drilling at a fixed depth to remove the copper foil from the hole wall of the through hole of the circuit board. At the same time, the external negative pressure device is turned on to generate negative pressure inside the suction tube. During the drilling process, the drill chips generated fall directly from the bottom of the through hole into the suction tube and are sucked away under the dual action of gravity and negative pressure suction. S5. After the back drilling of a single through hole is completed, drive the drill bit and suction tube to move backward synchronously to reset, and repeat steps S2 to S4 until the back drilling of all preset holes on the circuit board is completed.
[0013] Compared with the prior art, the beneficial effects of this invention are as follows: 1. The mutually perpendicular sliding structure consisting of a fixed base, a middle slide, and a top slide, combined with its hollow central layout, allows the circuit board to be precisely positioned below the concentric axis of the drill bit and the suction tube in the horizontal plane, while providing an interference-free vertical passage path for the suction tube; the drill bit and the suction tube move concentrically and synchronously towards each other, achieving precise hole alignment and immediate chip removal during back drilling, effectively avoiding hole deviation, hole blockage, and chip residue.
[0014] 2. By setting a hollow layout in the middle, when the middle slide and the top slide move in the horizontal plane, the hollow area ensures that the upward movement path of the suction tube will not collide with the slide body, regardless of the processing position, thus ensuring the continuity of movement.
[0015] 3. By using two sections of screw with opposite directions of rotation on the double-segment screw to engage with the upper and lower sliding plates respectively, a single drive source drives the drill bit and suction tube to move synchronously in opposite directions or in opposite directions. This simplifies the transmission structure and ensures that the drilling and suction actions are strictly synchronized without the need for additional coordination and control. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is one of the overall structural schematic diagrams of the present invention; Figure 2 This is the second schematic diagram of the overall structure of the present invention; Figure 3 This is one of the schematic diagrams of the drill suction assembly structure of the present invention; Figure 4 This is the second schematic diagram of the drill suction assembly structure of the present invention; Figure 5 This is a schematic diagram of the positioning component structure of the present invention; Figure 6 This is an exploded view of the positioning component structure of the present invention; Figure 7 This is a schematic diagram of the state during secondary drilling corresponding to the present invention.
[0017] The attached figures are labeled as follows: 1. Drill suction assembly; 11. Vertical pole; 12. Double-section screw; 13. Upper slide plate; 14. Drill platform module; 15. Drill bit; 16. Lower slide plate; 17. Clamping plate; 18. Sleeve rod; 19. Suction tube; 2. Positioning assembly; 21. Fixing base; 211. First optical axis; 212. First screw; 213. First closed-loop servo motor; 22. Intermediate slide; 221. Second optical axis; 222. Second screw; 223. Second closed-loop servo motor; 224. First sliding sleeve; 225. First rotating nut seat; 23. Top slide; 231. Fixing port; 232. Second rotating nut seat; 233. Second sliding sleeve; 3. Base; 4. Panel; 5. Third closed-loop servo motor. Detailed Implementation
[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0019] A multilayer circuit board drilling device, such as Figures 1-7 As shown, the system includes a base 3, a panel 4 fixedly mounted on the top of the base 3, a positioning component 2 above the panel 4, a fixed seat 21 fixedly mounted on the drill suction component 1, a middle slide 22 slidably mounted above the fixed seat 21, a top slide 23 slidably mounted above the middle slide 22, the middle slide 22 and the top slide 23 slide perpendicularly to each other above the fixed seat 21, the circuit board is placed on the top slide 23, the drill suction component 1 is mounted above the positioning component 2, the drill suction component 1 includes a drill platform module 14 positioned directly above the top slide 23, a suction tube 19 concentrically positioned below the drill bit 15, and the drill bit 15 and the suction tube 19 move synchronously towards or away from each other.
[0020] The base 3 forms the supporting foundation of the equipment, and a panel 4 is fixedly installed on its top. A positioning component 2 is installed above the panel 4. The positioning component 2 includes a fixed seat 21 fixedly installed on the drill suction component 1, a middle slide 22 slidably disposed above the fixed seat 21, and a top slide 23 slidably disposed above the middle slide 22. The middle slide 22 and the top slide 23 slide perpendicularly to each other above the fixed seat 21, forming a two-dimensional planar positioning mechanism. A multi-layer circuit board is placed on the top slide 23. Above the positioning component 2 is... The drilling and suction assembly 1 includes a drilling platform module 14 positioned directly above the top slide block 23. A drill bit 15 is positioned below the drilling platform module 14, and a suction tube 19 is concentrically positioned below the drill bit 15. The drill bit 15 and the suction tube 19 are configured to move synchronously towards or away from each other. When the drill bit 15 approaches the circuit board and performs back drilling, the suction tube 19 rises synchronously to below the through hole and is connected to the suction tube 19 through an external negative pressure device to immediately absorb the debris generated during the secondary drilling process, preventing debris residue from causing blockage in the hole.
[0021] A drill bit 15 is installed at the bottom of the drill platform module 14. The drill bit 15 moves up and down with the drill platform module 14, while the middle slide 22 and the top slide 23 drive the circuit board to move horizontally.
[0022] The drill bit 15 can rotate around its axis to perform secondary drilling on the existing through holes on the circuit board from above; the drill bit 15 moves up and down with the drill table module 14 to realize the feeding and retraction actions; the middle slide 22 and the top slide 23 drive the circuit board to move in two mutually perpendicular directions in the horizontal plane, so that the drill bit 15 can sequentially align with and process the through holes at different positions on the circuit board, and sequentially complete the multi-point back drilling operation.
[0023] The middle part of the fixed seat 21, the middle slide 22 and the top slide 23 are hollow. The middle part of the top slide 23 has a fixing opening 231, and the edge of the fixing opening 231 is stepped.
[0024] After the circuit board is placed on the top slide 23, it moves horizontally below the drill bit 15 along with the middle slide 22 and the top slide 23 to adjust the drilling position. Since the middle of the fixed seat 21, the middle slide 22 and the top slide 23 are connected, the suction tube 19 can be inserted into the through hole at any position on the circuit board from below without obstruction, ensuring that the debris is picked up synchronously during the back drilling process.
[0025] Uprights 11 are fixedly installed on both sides of the fixed base 21. An upper slide plate 13 is slidably installed between the two uprights 11. The drill rig module 14 is fixedly installed on the side wall of the upper slide plate 13. The uprights 11 improve the sliding stability of the upper slide plate 13. The sliding upper slide plate 13 drives the drill rig module 14 to move up and down.
[0026] The upright 11 provides vertical guidance for the upper slide plate 13, improving its stability when sliding up and down. When the upper slide plate 13 slides along the upright 11, it drives the drill platform module 14 and the drill bit 15 on it to move up and down synchronously, realizing back drilling feed and retraction actions.
[0027] A sliding plate 16 is slidably disposed below the panel 4. A clamping plate 17 is fixedly installed on the side wall of the sliding plate 16. A sleeve rod 18 is fixedly installed on the clamping plate 17. The sleeve rod 18 passes through the panel 4, and the suction tube 19 is inserted into the top of the sleeve rod 18.
[0028] A sleeve rod 18 is fixedly installed on the clamping plate 17. The sleeve rod 18 passes through the panel 4 and can move up and down along it. The suction tube 19 is inserted into the top of the sleeve rod 18, and the bottom of the sleeve rod 18 is connected to an external negative pressure device. When the sleeve rod 18 drives the suction tube 19 to move upward and insert into the through hole of the circuit board, it is synchronized with the back drilling action of the upper drill bit 15 to perform negative pressure adsorption on the debris generated during the drilling process, preventing debris from remaining or falling into the hole.
[0029] A double-segment screw 12 is rotatably mounted on the side of the upright 11 near the upper slide plate 13. The double-segment screw 12 has two sections of threads with opposite helical directions. The ends of the upper slide plate 13 and the lower slide plate 16 are respectively connected to the two ends of the double-segment screw 12 through threads. A third closed-loop servo motor 5 is fixedly mounted on the top of the upright 11. The output shaft of the third closed-loop servo motor 5 is connected to the double-segment screw 12.
[0030] The double-segment screw 12 has two sections of threads with opposite helical directions. The ends of the upper slide plate 13 and the lower slide plate 16 are respectively connected to the two ends of the double-segment screw 12 through threads. A third closed-loop servo motor 5 is fixedly installed on the top of the upright 11. The output shaft of the third closed-loop servo motor 5 is coaxially connected to the double-segment screw 12 to drive its rotation. When the third closed-loop servo motor 5 is working, the double-segment screw 12 synchronously drives the upper slide plate 13 and the lower slide plate 16 to move in opposite directions or in opposite directions, thereby realizing the linkage feed of the drill bit 15 and the suction tube 19. The specific model of the third closed-loop servo motor 5 is FISCHERPF-30-24 / 1.
[0031] A pair of first sliding sleeves 224 are fixedly installed on both sides of the bottom of the intermediate slide block 22. A first optical shaft 211 is rotatably installed on both sides of the top of the fixed seat 21. The first sliding sleeves 224 are slidably sleeved on the first optical shaft 211. A first rotating nut seat 225 is fixedly installed on the bottom of the intermediate slide block 22. A first screw 212 is rotatably installed on the top of the fixed seat 21. The first screw 212 is connected to the first rotating nut seat 225 by threads. A first closed-loop servo motor 213 is fixedly installed on one side of the fixed seat 21.
[0032] The first closed-loop servo motor 213 drives the first screw 212 to rotate via the rotating shaft, thereby causing the first rotating nut seat 225 to move axially along the first screw 212, so that the intermediate slide 22 slides on the fixed seat 21 along the first optical axis 211, thereby realizing the horizontal position adjustment of the circuit board.
[0033] The top slide block 23 has a second sliding sleeve 233 fixedly installed on both sides of its bottom. The middle slide block 22 has a second optical shaft 221 rotatably installed on both sides of its top. The second sliding sleeve 233 is slidably sleeved on the second optical shaft 221. The bottom of the top slide block 23 has a second rotating nut seat 232 fixedly installed. The top of the middle slide block 22 has a second screw 222 rotatably installed. The second screw 222 is threadedly connected to the second sliding sleeve 233. The middle slide block 22 has a second closed-loop servo motor 223 fixedly installed on one side.
[0034] The second closed-loop servo motor 223 drives the second screw 222 to rotate, thereby causing the second rotating nut seat 232 to move axially, so that the top slide 23 slides on the middle slide 22 along the second optical axis 221, thereby realizing the adjustment of the circuit board in a position perpendicular to the aforementioned direction of movement.
[0035] The second optical axis 221 is arranged perpendicularly to the first optical axis 211, making the sliding directions of the top slide 23 and the middle slide 22 orthogonal, thus forming a two-dimensional planar positioning mechanism. The first closed-loop servo motor 213 and the second closed-loop servo motor 223 are both of model 0RK1A-AW2J, which are used to drive the first screw 212 and the second screw 222 respectively, so as to realize the independent and precise position adjustment of the circuit board in two horizontal directions. Furthermore, bearings can be added at necessary positions in this solution to improve stability. This is a widely used technical means in the field, and its specific structure and working principle belong to the prior art in the field, which will not be described in detail here.
[0036] A back-drilling process for multilayer circuit boards includes the following steps: S1. Place the multilayer circuit board to be processed on the top slide 23 and use the stepped edge of the fixing port 231 to fix the circuit board in place, so that the circuit board is located between the drill bit 15 and the suction tube 19. This positioning method can limit the movement of the circuit board in the vertical and horizontal directions, ensure that it remains stable during back drilling, and avoid hole position displacement or drilling deviation due to displacement. S2. According to the preset drilling coordinates, control the positioning component 2 to work. By using the mutual perpendicular sliding of the middle slide 22 and the top slide 23, drive the circuit board to move horizontally and accurately align the center of the through hole to be back drilled on the circuit board to the concentric axis of the drill bit 15 and the suction tube 19. High-precision two-dimensional positioning is achieved through the orthogonal slide structure to ensure that the drill bit 15 and the suction tube 19 are always coaxial with the target through hole, providing a centering basis for synchronous drilling and chip removal. S3. Start the drilling and suction assembly 1, and drive the drill bit 15 and the suction tube 19 to move synchronously towards each other; that is, the drill bit 15 feeds downward to approach the upper surface of the circuit board, while the suction tube 19 moves upward through the hollow area of the fixed seat 21, the middle slide 22 and the top slide 23 until the top of the suction tube 19 is inserted into the through hole. The synchronous movement ensures that the suction tube 19 is in place before the drilling begins, avoiding debris from falling before suction. At the same time, the hollow structure provides the suction tube 19 with an interference-free vertical channel. S4, Drill bit 15 performs fixed-depth back drilling on the through holes of the circuit board to remove the copper foil from the hole walls. At the same time, the external negative pressure device is turned on to generate negative pressure inside the suction tube 19. During the drilling process, the drill chips generated fall directly from the bottom of the through hole into the suction tube 19 under the dual action of gravity and negative pressure suction and are sucked away. The drilling and suction are combined with negative pressure adsorption to remove copper chips and dielectric debris in time, effectively preventing the residue in the hole, hole blockage or debris from contaminating the board surface, improving the back drilling quality and the reliability of subsequent electrical performance. S5. After the back drilling of a single through hole is completed, the drive drill bit 15 and the suction tube 19 move backward synchronously to reset. Repeat steps S2 to S4 until the back drilling of all preset holes on the circuit board is completed. This cycle process realizes automatic continuous operation of multiple holes, with good overall structural coordination, high processing efficiency, and consistent chip removal effect for each hole.
[0037] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A multilayer circuit board drilling device, characterized in that, The device includes a base (3), a panel (4) is fixedly installed on the top of the base (3), a positioning component (2) is provided above the panel (4), the positioning component (2) includes a fixed seat (21) fixedly installed on the panel (4), a middle slide (22) is slidably provided above the fixed seat (21), a top slide (23) is slidably provided above the middle slide (22), the middle slide (22) and the top slide (23) slide perpendicularly to each other above the fixed seat (21), the circuit board is placed on the top slide (23), a drill suction component (1) is provided above the positioning component (2), the drill suction component (1) includes a drill platform module (14) provided directly above the top slide (23), a drill bit (15) is installed at the bottom of the drill platform module (14), a suction tube (19) is concentrically provided below the drill bit (15), the drill bit (15) and the suction tube (19) move synchronously towards or away from each other.
2. The multilayer circuit board drilling device according to claim 1, characterized in that, The drill bit (15) is installed at the bottom of the drill platform module (14). The drill bit (15) moves up and down with the drill platform module (14), and the middle slide (22) and the top slide (23) drive the circuit board to move horizontally.
3. The multilayer circuit board drilling device according to claim 1, characterized in that, The middle part of the fixed seat (21), the middle slide (22) and the top slide (23) are hollow. The middle part of the top slide (23) has a fixing opening (231) with the edge of the fixing opening (231) being stepped.
4. The multilayer circuit board drilling device according to claim 1, characterized in that, Uprights (11) are fixedly installed on both sides of the fixed base (21). An upper slide plate (13) is slidably installed between the two uprights (11). The drilling module (14) is fixedly installed on the side wall of the upper slide plate (13). The uprights (11) improve the sliding stability of the upper slide plate (13). The sliding upper slide plate (13) drives the drilling module (14) to move up and down.
5. The multilayer circuit board opening device according to claim 4, characterized in that, A sliding plate (16) is slidably provided below the panel (4). A clamp (17) is fixedly installed on the side wall of the sliding plate (16). A sleeve rod (18) is fixedly installed on the clamp (17). The sleeve rod (18) passes through the panel (4). A suction tube (19) is inserted into the top of the sleeve rod (18).
6. The multilayer circuit board drilling device according to claim 5, characterized in that, A double-segment screw (12) is rotatably installed on the side of the upright (11) near the upper slide plate (13). The double-segment screw (12) has two sections of threads with opposite spiral directions. The ends of the upper slide plate (13) and the lower slide plate (16) are respectively connected to the two ends of the double-segment screw (12) through threads. A third closed-loop servo motor (5) is fixedly installed on the top of the upright (11). The output shaft of the third closed-loop servo motor (5) is connected to the double-segment screw (12).
7. The multilayer circuit board drilling device according to claim 1, characterized in that, A pair of first sliding sleeves (224) are fixedly installed on both sides of the bottom of the intermediate slide (22). A first optical shaft (211) is rotatably installed on both sides of the top of the fixed seat (21). The first sliding sleeves (224) are slidably sleeved on the first optical shaft (211). A first rotating nut seat (225) is fixedly installed at the bottom of the intermediate slide (22). A first screw (212) is rotatably installed at the top of the fixed seat (21). The first screw (212) is connected to the first rotating nut seat (225) by a thread. A first closed-loop servo motor (213) is fixedly installed on one side of the fixed seat (21). The top slide (23) has a second slide sleeve (233) fixedly installed on both sides of the bottom. The middle slide (22) has a second optical axis (221) rotatably installed on both sides of the top. The second slide sleeve (233) is slidably sleeved on the second optical axis (221). The bottom of the top slide (23) has a second rotating nut seat (232) fixedly installed. The top of the middle slide (22) has a second screw (222) rotatably installed. The second screw (222) and the second rotating nut seat (232) are connected by threads. The middle slide (22) has a second closed-loop servo motor (223) fixedly installed on one side. The second optical axis (221) is perpendicular to the first optical axis (211).
8. A multilayer circuit board back drilling process, comprising the multilayer circuit board drilling equipment as described in any one of claims 1-7, characterized in that: Includes the following steps: S1. Place the multilayer circuit board to be processed on the top slide (23), and use the stepped edge of the fixing port (231) to fix the circuit board in place, so that the circuit board is located between the drill bit (15) and the suction tube (19). S2. According to the preset drilling coordinates, control the positioning component (2) to work, and use the mutual vertical sliding of the middle slide (22) and the top slide (23) to drive the circuit board to move horizontally, and accurately align the center of the through hole to be back drilled on the circuit board to the concentric axis of the drill bit (15) and the suction tube (19). S3. Start the drill and suction assembly (1) to drive the drill bit (15) and suction tube (19) to move in opposite directions synchronously; that is, the drill bit (15) feeds downward to approach the upper surface of the circuit board, while the suction tube (19) moves upward through the hollow area of the fixed seat (21), the middle slide (22) and the top slide (23) until the top of the suction tube (19) is inserted into the through hole; S4. The drill bit (15) performs back drilling at a fixed depth to remove the copper foil from the hole wall of the circuit board through hole. At the same time, the external negative pressure device is turned on to generate negative pressure inside the suction tube (19). During the drilling process, the drill chips generated fall directly from the bottom of the through hole into the suction tube (19) and are sucked away under the dual action of gravity and negative pressure suction. S5. After the back drilling of a single through hole is completed, drive the drill bit (15) and the suction tube (19) to move back and reset synchronously. Repeat steps S2 to S4 until the back drilling of all preset holes on the circuit board is completed.