back drill

Abstract

The utility model belongs to the technical field of circuit board processing and manufacturing, disclose a back drill, including the feed section, cylindrical section, the link section, the cutting edge section and the handle that connect each other, feed section and link section all are set to the taper structure with spiral chip flute, the big end of feed section is connected with cylindrical section, and the diameter of cylindrical section is same with the diameter of big end of feed section, the small end of link section is connected with cylindrical section, the big end of link section is connected with cutting edge section, and cutting edge section has spiral chip flute. The utility model discloses through setting feed section and cylindrical section, feed section has certain orientation effect, can avoid the problem of partial hole of back drill at the feed, improves the alignment, and feed section sets up the taper structure with spiral chip flute, and it is convenient to drill cover plate, and it is convenient to chip removal, cylindrical section plays the role of orientation in the back drilling process of back drill, it can also penetrate through the hole, and the drill chips generated in the back drilling process are discharged from the through -hole, avoid the problem of hole blockage.

Description

Technical Field

[0001] This utility model relates to the field of circuit board processing and manufacturing technology, and in particular to a back drill bit. Background Technology

[0002] As the printed circuit board (PCB) industry continues to develop, electronic devices are constantly evolving towards higher speeds and greater integration. This has led downstream customers to place more stringent demands on the reliability of PCB products, especially for high-speed signal board back-drilling products, which are widely used in high-speed signal transmission scenarios. The quality of back-drilling directly determines the stability and integrity of signal transmission and has become a core focus for customers.

[0003] The back-drilling process for high-speed signal boards essentially reduces signal reflection and crosstalk by removing redundant hole segments (i.e., back-drill stubs) along the high-speed signal transmission path, thereby ensuring the effective transmission of high-speed signals. When the drill bit drills into the PCB substrate and copper layer, a large amount of copper and substrate chips are generated. If the chip removal system of the processing equipment fails to remove these chips in a timely and sufficient manner, the chips will be squeezed into the through-hole formed by the back drill under the drilling pressure, leading to partial or complete blockage of the through-hole, resulting in a back-drill blocked hole.

[0004] Related technologies typically employ ultrasonic water washing or adhesive removal methods to remove foreign matter residue inside the holes. However, these methods are largely ineffective for severe blockages caused by foreign matter or copper shavings. In such cases, manual cleaning is the only option, which is extremely inefficient and virtually impossible to clean small holes. Utility Model Content

[0005] The purpose of this utility model is to provide a back drill bit that solves the problems of easy clogging of back drill holes in the prior art, poor cleaning after clogging, and low cleaning efficiency. The back drill bit of this utility model can effectively avoid the occurrence of clogging problems.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A back drill bit includes: an infeed section, a cylindrical section, a connecting section, a cutting edge section, and a shank connected to each other. The infeed section and the connecting section are both configured as conical structures with helical chip removal grooves. The large end of the infeed section is connected to the cylindrical section, and the diameter of the cylindrical section is the same as the diameter of the large end of the infeed section. The small end of the connecting section is connected to the cylindrical section, and the large end of the connecting section is connected to the cutting edge section, which has helical chip removal grooves.

[0008] In some possible implementations, the taper of the feed section is the same as the taper of the connecting section.

[0009] In some possible implementations, the diameter of the cylindrical segment is r, and the diameter of the through hole is R.

[0010] In some possible implementations, the length of the cylindrical segment is A2, and the copper retention length is h1, where h1 ≤ A2.

[0011] In some possible implementations, the diameter of the handle is greater than or equal to the diameter of the cutting edge.

[0012] In some possible implementations, the length of the feed section is A1, the length of the cylindrical section is A2, the length of the connecting section is A3, the length of the cutting edge section is A4, and the drilling depth of the back drill in the PCB board is H, where A1+A2+A3+A4>H.

[0013] In some possible implementations, when the back drill bit reaches its deepest point, the distance between the end face of the cutting edge segment away from the connecting segment and the end face of the cover plate away from the PCB board is d, where d ≥ 1.3 mm.

[0014] In some possible implementations, when the back drill reaches its deepest point, the feed section protrudes from the first surface of the PCB board away from the cover plate, and the end face of the large end of the feed section is flush with the first surface.

[0015] In some possible implementations, the spiral chip removal groove of the cutting edge segment is a double-edged, double-groove structure; and / or, the spiral chip removal groove of the connecting segment is a double-edged, double-groove structure.

[0016] In some possible implementations, the handle is detachably connected to the blade section; the handle is fitted with an anti-slip sleeve.

[0017] The beneficial effects of this utility model are:

[0018] The back drill bit provided by this utility model features an infeed section and a cylindrical section. The infeed section pre-opens the cover plate, allowing the back drill bit to initially enter the through hole to be back drilled. The infeed section provides a guiding function, preventing the back drill bit from deviating at the infeed point and improving alignment. The infeed section is also designed with a conical structure featuring a spiral chip removal groove, facilitating drilling down the cover plate and chip removal. After entering the through hole, the cylindrical section performs another pre-positioning, preventing misalignment between the axis of the back drill hole and the axis of the through hole without damaging the copper layer on the hole wall, further improving alignment. Additionally, the cylindrical section guides the back drill bit during back drilling and penetrates the through hole, pushing the drill chips generated during back drilling out of the through hole and preventing blockage. A connecting section, also with a conical structure featuring a spiral chip removal groove, facilitates drilling down and chip removal. The cutting edge section also has a spiral chip removal groove for chip removal. A tool holder supports the cutting edge section and facilitates connection to external components. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the back drill bit provided in an embodiment of the present utility model;

[0020] Figure 2 This is a schematic diagram of the back drill bit in the first state (the feed section passes through the cover plate) when drilling with the present utility model embodiment;

[0021] Figure 3 This is a schematic diagram of the back drill bit in the second state (connecting section passes through the cover plate) when drilling with the present utility model embodiment;

[0022] Figure 4 This is a schematic diagram of the back drill bit in the third state (drilling to the deepest point) when drilling, as provided in the embodiment of this utility model.

[0023] In the picture:

[0024] 10. Back drill bit; 20. PCB board; 21. Through hole; 22. Signal transmission layer; 30. Cover plate;

[0025] 100, feed section; 200, cylindrical section; 300, connecting section; 400, cutting edge section; 500, tool holder. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0027] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0030] Back drilling essentially reduces signal reflection and crosstalk by removing redundant vias (i.e., back drill stubs) from the high-speed signal transmission path. During back drilling, a cover plate (such as an aluminum plate) is usually placed on the surface of the PCB board. The cover plate typically serves a conductive function and assists the back drill bit in calculating the drilling depth.

[0031] like Figures 1 to 4 As shown, this embodiment provides a back drill bit 10, including an infeed section 100, a cylindrical section 200, a connecting section 300, a cutting edge section 400, and a shank 500 connected to each other. The infeed section 100 and the connecting section 300 are both configured as conical structures with spiral chip removal grooves. The large end of the infeed section 100 is connected to the cylindrical section 200, and the diameter of the cylindrical section 200 is the same as the diameter of the large end of the infeed section 100. The small end of the connecting section 300 is connected to the cylindrical section 200, and the large end of the connecting section 300 is connected to the cutting edge section 400, which has spiral chip removal grooves.

[0032] The back drill bit 10 provided in this embodiment, by setting an infeed section 100 and a cylindrical section 200, first pre-opens the cover plate 30, so that the back drill bit 10 initially enters the through hole 21 to be back drilled. The infeed section 100 has a certain guiding function, which can avoid the back drill bit 10 from deviating at the infeed point, improve the alignment, and the infeed section 100 is set as a conical structure with a spiral chip removal groove, which facilitates drilling down the cover plate 30 and facilitates chip removal. After the cylindrical section 200 enters the through hole 21, it is pre-positioned again, and at the same time, without damaging the copper layer set on the hole wall of the through hole 21, it avoids To prevent misalignment between the axis of the back drill hole to be drilled and the axis of the through hole 21, the alignment is improved. In addition, the cylindrical section 200 plays a guiding role during the back drilling process of the back drill bit 10. It can also penetrate through the through hole 21 to push the drill chips generated during the back drilling process out of the through hole 21, avoiding the problem of hole blockage. By setting the connecting section 300, which is a conical structure with a spiral chip removal groove, it is easy to drill down and easy to remove chips. The cutting edge section 400 has a spiral chip removal groove to facilitate chip removal. By setting the tool holder 500, the tool holder 500 is used to support the cutting edge section 400, which is convenient for connection with external equipment.

[0033] Optionally, the taper of the feed section 100 is the same as that of the connecting section 300. This equal taper design of the feed section 100 and the connecting section 300 helps ensure their coaxiality during machining; it also ensures the uniformity and continuity of the drilling process as the connecting section 300 continues to drill.

[0034] like Figure 4 As shown, in this embodiment, the diameter of the cylindrical segment 200 is r, and the diameter of the through hole 21 is R. ≤r≤R-0.1mm. The diameter of the cylindrical segment 200 is smaller than the diameter of the through hole 21, allowing the cylindrical segment 200 to pass through the through hole 21 without damaging the copper layer on the hole wall of the through hole 21; by setting It covers alignment error and reserves an alignment accuracy of 0.05mm.

[0035] Optionally, the length of the cylindrical segment 200 is A2, and the copper retention length is h1, where h1 ≤ A2. Typically, the back-drilled stub is located in a portion of the signal transmission layer 22 near the cover plate 30, such as... Figure 4 As shown, taking the cylindrical section 200 and the copper-retained portion in the through hole 21 as parallel to each other as an example, the length of the back drill stub in the figure is h2, and the length of the copper-retained portion is h1. If h1 > A2, the copper-retained portion of the connecting section 300 penetrates through the through hole 21, which means that the cylindrical section 200 does not completely penetrate the copper-retained portion in the through hole 21, which can easily lead to drill cuttings remaining in the through hole 21 and causing hole blockage.

[0036] Optionally, the diameter of the shank 500 is greater than or equal to the diameter of the cutting edge section 400. The shank 500 is the connecting carrier between the back drill 10 and external equipment. If the diameter of the shank 500 is greater than or equal to the diameter of the cutting edge section 400, the shank 500 has a higher moment of inertia, which can transmit force more stably and resist deformation. If the diameter of the shank 500 is greater than or equal to the diameter of the cutting edge section 400, the shank 500 has stronger rigidity and is less prone to tool breakage.

[0037] Preferably, the length of the feed section 100 is A1, the length of the cylindrical section 200 is A2, the length of the connecting section 300 is A3, the length of the cutting edge section 400 is A4, and the drilling depth of the back drill 10 within the PCB board 20 is H, where A1+A2+A3+A4>H. This ensures that the back drill 10 has a sufficiently long effective length for chip removal and drilling during the drilling process, which is beneficial for improving the adequacy of chip removal.

[0038] In this embodiment, when the back drill 10 drills to its deepest point, the distance between the end face of the cutting edge 400 away from the connecting section 300 and the end face of the cover plate 30 away from the PCB board 20 is d, where d ≥ 1.3 mm. This ensures that the cutting edge 400 has sufficient effective length for drilling. If the distance between the end face of the cutting edge 400 away from the connecting section 300 and the end face of the cover plate 30 away from the PCB board 20 is too small, the shank 500 may collide with the cover plate 30, causing damage to the cover plate 30; if the distance between the end face of the cutting edge 400 away from the connecting section 300 and the end face of the cover plate 30 away from the PCB board 20 is too large, the entire back drill 10 will be too long, increasing manufacturing costs.

[0039] Preferably, when the back drill 10 drills to its deepest point, the feed section 100 protrudes from the first surface of the PCB board 20 away from the cover plate 30, and the large end face of the feed section 100 is flush with the first surface. This ensures that the back drill 10 protrudes from the PCB board 20 by a sufficient length, preventing drill bits from getting stuck between the feed section 100 and the hole wall of the through hole 21, and allowing the drill bits to be fully discharged.

[0040] In this embodiment, the spiral chip removal groove of the cutting edge section 400 has a double-edge, double-groove structure; and / or, the spiral chip removal groove of the connecting section 300 has a double-edge, double-groove structure. The double-edge, double-groove structure means that two spiral grooves are evenly distributed on the circumference of the cutting edge section 400 and the connecting section 300, and the edge of each groove forms a main cutting edge. The symmetrical layout achieves cutting force balance, smooth chip removal, and machining stability.

[0041] Preferably, the handle 500 and the cutting edge 400 are detachably connected, and the handle 500 is fitted with an anti-slip sleeve. This detachable connection improves ease of assembly and disassembly; the anti-slip sleeve cushions vibrations and impacts during manual operation, enhancing safety and comfort; and it protects the handle 500 from contamination by water, oil, etc.

[0042] The usage process of the back drill bit 10 in this embodiment includes:

[0043] S1. Process and manufacture 20 PCB boards to be back drilled;

[0044] S2. Machining back drill bit 10 and adjusting the drilling depth of back drill bit 10;

[0045] S3. Set a cover plate 30 on the PCB board 20;

[0046] S4. Use a back drill bit 10 to back drill and check for any abnormalities such as blockage.

[0047] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A back drill bit, characterized in that, include: The tool consists of an interconnected feed section (100), a cylindrical section (200), a connecting section (300), a cutting edge section (400), and a tool holder (500). The feed section (100) and the connecting section (300) are both configured as conical structures with spiral chip removal grooves. The large end of the feed section (100) is connected to the cylindrical section (200), and the diameter of the cylindrical section (200) is the same as the diameter of the large end of the feed section (100). The small end of the connecting section (300) is connected to the cylindrical section (200), and the large end of the connecting section (300) is connected to the cutting edge section (400). The cutting edge section (400) has spiral chip removal grooves.

2. The back drill bit according to claim 1, characterized in that, The taper of the feed section (100) is the same as the taper of the connecting section (300).

3. The back drill bit according to claim 1, characterized in that, The diameter of the cylindrical segment (200) is r, and the diameter of the through hole (21) is R.

4. The back drill bit according to claim 1, characterized in that, The length of the cylindrical segment (200) is A2, and the copper retention length is h1, where h1 ≤ A2.

5. The back drill bit according to claim 1, characterized in that, The diameter of the handle (500) is greater than or equal to the diameter of the cutting edge (400).

6. The back drill bit according to claim 1, characterized in that, The length of the feed section (100) is A1, the length of the cylindrical section (200) is A2, the length of the connecting section (300) is A3, the length of the cutting edge section (400) is A4, and the drilling depth of the back drill in the PCB board (20) is H, where A1+A2+A3+A4>H.

7. The back drill bit according to claim 1, characterized in that, When the back drill bit drills to the deepest point, the distance between the end face of the cutting edge segment (400) away from the connecting segment (300) and the end face of the cover plate (30) away from the PCB board (20) is d, where d ≥ 1.3 mm.

8. The back drill bit according to claim 1, characterized in that, When the back drill bit drills to the deepest point, the feed section (100) protrudes from the first surface of the PCB board (20) away from the cover plate (30), and the end face of the large end of the feed section (100) is flush with the first surface.

9. The back drill bit according to claim 1, characterized in that, The spiral chip removal groove of the cutting edge section (400) is a double-edged double-groove structure; and / or, the spiral chip removal groove of the connecting section (300) is a double-edged double-groove structure.

10. The back drill bit according to claim 1, characterized in that, The handle (500) is detachably connected to the blade section (400); the handle (500) is fitted with an anti-slip sleeve.

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