Double-edge single-groove drill bit and drilling method

Abstract

The invention discloses a double-edge single-groove drill bit and a drilling method, the double-edge single-groove drill bit comprises a cutter handle and a drill body, the two ends of the drill body are a drill tip end and a drill tail end respectively, the double-edge single-groove drill bit adopts front-end double-groove design and rear-end single-groove design, the front-end double-groove design is beneficial to cutting stress balance and cutter breaking risk reduction, and the rear-end single-groove design is beneficial to rigidity enhancement and step reduction; meanwhile, the large-core-thickness design is adopted, the rigidity of the drill bit is enhanced, the cutter breaking risk is reduced, and steps are reduced. According to the double-edge single-groove drill bit and the drilling method, the unsmooth hole wall caused by opposite drilling can be improved, and then dust blocking or hole copper separation after electroplating is improved.

Description

Technical Field

[0001] The invention relates to the technical field of drilling equipment, and in particular to a double-edged single-groove drill bit and a drilling method. Background Art

[0002] With the development of 5G, cloud computing, and the Internet of Things, the functions and complexity of electronic devices have increased, and the number of PCB layers has increased, the thickness has become thicker, and the aperture has become smaller. We generally call PCB boards with an aspect ratio of more than 30 times as ultra-high aspect ratio PCB boards. For such ultra-high aspect ratio PCB boards, the aspect ratio of the drill bit is very large, so the rigidity is very poor, and it is easy to have problems such as broken tools and offset holes. For this, drilling is usually performed to reduce the aspect ratio of the drill bit and ensure the rigidity of the drill bit. However, this will cause step problems due to alignment deviation, and the step problem will cause the hole wall to be uneven, which is easy to cause dust plugging or copper separation in the hole after electroplating. Summary of the invention

[0003] The object of the present invention is to provide a double-edged single-slot drill bit and a drilling method to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or create conditions.

[0004] The technical solutions adopted to solve the above technical problems are: A double-edge single-groove drill bit comprises a drill body, wherein the two ends of the drill body are respectively a drill tip and a drill tail end, the drill body comprises a double-groove section and a single-groove section arranged in sequence from the drill tip to the drill tail end, the outer circumference of the drill body is provided with a main spiral groove spirally arranged from the drill tip to the drill tail end, the main spiral groove spans the double-groove section and the single-groove section, the outer circumferential wall of the double-groove section is provided with a spirally arranged secondary spiral groove, one end of the secondary spiral groove extends to the drill tip, and the other end intersects with the main spiral groove between the double-groove section and the single-groove section, a drill core is formed between the main spiral groove and the secondary spiral groove, and the ratio of the thickness of the drill core to the diameter of the drill body varies in the range of 50% to 90%.

[0005] The beneficial effects of the present invention are: The double-edged single-groove drill bit has a double-groove design at the front end and a single-groove design at the rear end. The double-groove design at the front end helps balance the cutting force and reduce the risk of tool breakage, while the single-groove design at the rear end helps enhance rigidity, and the step 411 formed by drilling is smoother. At the same time, the large core thickness design helps enhance the rigidity of the drill bit, reduces the risk of tool breakage, and reduces the inclination of the step formed by drilling. The present invention is used for grinding the drill when drilling deep holes, and can improve the uneven hole wall caused by the drill, thereby improving dust plugging or copper separation in the hole after electroplating.

[0006] As a further improvement of the above technical solution, the auxiliary spiral groove and the main spiral groove located on the double groove section are arranged in a central symmetric manner with respect to the axis of the drill body.

[0007] As a further improvement of the above technical solution, the drill tip is provided with a conical drill tip body, and the tip angle of the drill tip body is 60°~120°.

[0008] As a further improvement of the above technical solution, the drill tip body is provided with two main cutting faces, two secondary cutting faces connected to the long side lines of the main cutting faces, and a chisel edge is provided at the connection between the two main cutting faces.

[0009] As a further improvement of the above technical solution, the helix angles of the main spiral groove and the secondary spiral groove on the double-groove segment vary in the range of 35° to 55°.

[0010] As a further improvement of the above technical solution, the helix angle of the main spiral groove located on the single groove segment varies in the range of 45° to 60°.

[0011] The present invention also provides a drilling method for drilling holes in a PCB board, the drilling method comprising: Drilling a first guide hole of a first depth on one side of the PCB board using a short-blade long drill bit; Drilling the first guide hole to a second depth using a long-edge long drill bit; Drilling the first guide hole to a third depth by using the double-edge single-flute drill bit as claimed in claims 1 to 6; Drilling a second guide hole of a first depth at a position corresponding to the first guide hole on the other side of the PCB board by using a short-blade long drill bit; Drilling the first guide hole to a second depth using a long-edge long drill bit; The first guide hole is drilled through the PCB board by using the double-edge single-slot drill bit.

[0012] As a further improvement of the above technical solution, between drilling the first guide hole of the first depth on one side of the PCB board by a short-blade long drill bit and drilling the first guide hole to the second depth by a long-blade long drill bit, the method also includes drilling the first guide hole to a fourth depth by a drill bit with an intermediate blade length.

[0013] As a further improvement of the above technical solution, a first guide hole of a first depth is drilled on one side of the PCB board by a short-blade long drill bit, wherein the first depth ranges from 0.5 mm to 1.0 mm.

[0014] As a further improvement of the above technical solution, the first guide hole is drilled to a third depth by the double-edged single-slot drill bit as described in claims 1 to 6, wherein the third depth ranges from half the thickness of the PCB board + 0.3mm to 0.7mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments; Figure 1 A double-edge single-groove drill bit provided by the present invention is a schematic diagram of a drill point angle and a helix angle of an embodiment thereof; Figure 2 This is a schematic diagram of the tool structure of a double-edged single-groove drill bit provided by the present invention; Figure 3 A schematic diagram of the core thickness of a double-edge single-groove drill bit provided by the present invention; Figure 4 Schematic diagram of drilling process; Figure 5 Schematic diagram of drilling without steps; Figure 6 Schematic diagram of normal drilling steps; Figure 7 Schematic diagram of the improved step of the present invention; Figure 8 A drilling method provided by the present invention and a schematic diagram of the process flow of one embodiment thereof.

[0016] Reference numerals: Tool handle 100, drill body 200, main cutting face 201, secondary cutting face 202, chisel edge 203, double groove section 210, main spiral groove 211, secondary spiral groove 212, single groove section 220, drill point angle 300, PCB board 400, through hole 410, step 411, short-edge long drill bit 500, long-edge long drill bit 600, double-edge single-groove drill bit 700. DETAILED DESCRIPTION

[0017] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0018] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0019] In the description of the present invention, if there are words such as "several", it means one or more, "more" means more than two, greater than, less than, exceed, etc. are understood as not including the number, and above, below, within, etc. are understood as including the number.

[0020] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0021] Reference Figures 1 to 8 The present invention provides a double-edged single-groove drill and a drilling method as follows: A double-edged single-groove drill bit comprises a shank 100 and a drill body 200 connected to each other, wherein the two ends of the drill body 200 are respectively a drill tip and a drill tail end, and the drill body 200 comprises a double-groove section 210 and a single-groove section 220 which are sequentially arranged from the drill tip to the drill tail end, and the outer periphery of the drill body 200 is provided with a main spiral groove 211 which is spirally arranged from the drill tip to the drill tail end, and the main spiral groove 211 spans the double-groove section 210 and the single-groove section 220, and the outer peripheral wall of the double-groove section 210 is provided with a spirally arranged auxiliary spiral groove 212, one end of the auxiliary spiral groove 212 extends to the drill tip, and the other end intersects with the main spiral groove 211 between the double-groove section 210 and the single-groove section 220, and the auxiliary spiral groove 212 and the main spiral groove 211 located on the double-groove section 210 are centrally symmetrically arranged with respect to the axis of the drill body 200.

[0022] The double-edge single-groove drill 700 has a double-groove design at the front end and a single-groove design at the rear end. The double-groove design at the front end helps to balance the cutting force and reduce the risk of tool breakage, and the single-groove design at the rear end helps to enhance rigidity, and the step 411 produced by drilling is smoother. That is, the double-groove section 210 not only increases the number of cutting edges, but also improves the utilization rate of the cutting edges. The cooperation between the secondary spiral groove 212 and the main spiral groove 211 makes the cutting force distribution more uniform, further improving the cutting efficiency and chip removal performance. The helix angle of the main spiral groove 211 and the secondary spiral groove 212 located on the double-groove section 210 varies from 35° to 55°, and this design can optimize the distribution of the cutting force. During the cutting process, the cutting force will be distributed along the direction of the spiral groove, and the appropriate helix angle can make the cutting force act more evenly on various parts of the drill bit, reduce the vibration and deviation of the drill bit, and improve the processing accuracy and surface quality. The helix angle of the main spiral groove 211 located on the single-groove section 220 varies from 45° to 60°, and this design can improve the cutting efficiency. A larger helix angle can increase the cutting area, thereby removing more material in one cutting process. At the same time, such a design also helps to discharge the chips smoothly, reduce the risk of chip accumulation and blockage, and maintain the stability and continuity of the cutting process. In addition, by adopting different helix angles for the double groove section 210 and the single groove section 220, friction and wear during the cutting process can be reduced, thereby extending the service life of the drill bit. In addition, the double-edge single groove design also increases the strength and rigidity of the drill bit, making the drill bit less likely to be damaged when subjected to large cutting forces.

[0023] The drill tip is provided with a conical drill tip body, the drill tip angle is 60° to 120°, and a smaller drill tip angle 300 is used. The smaller drill tip angle 300 can ensure that the step 411 produced by drilling is smoother, and reduce the risk of dust plugging or copper separation in the hole after electroplating. The drill tip includes two main cutting faces 201, two secondary cutting faces 202 connected to the long side lines of the main cutting faces 201, and a chisel edge 203 is provided at the connection between the two main cutting faces 201.

[0024] A drill core is formed between the main spiral groove 211 and the secondary spiral groove 212. The ratio of the drill core thickness to the diameter of the drill body 200 varies in the range of 50% to 90%. The large core thickness design helps to enhance the drill bit rigidity, reduce the risk of tool breakage, and at the same time, form an inclination of the step 411 during drilling.

[0025] The present invention is used for grinding the drill bit when drilling deep holes, which helps to reduce the inclination of the step 411 formed by the drilling. Because the drill point angle 300 of the present invention is small, the radial force is large when drilling, resulting in a large deflection of the drill bit, so the drill bit of the present invention cannot be used to replace the long-blade long drill bit 600 for processing. Therefore, the long-blade long drill bit 600 is required for drilling. The specific operation is as follows: Reference Figure 4 and Figure 8 For a PCB board 400 with a thickness-to-diameter ratio of 30 to 35 times, use a drill to process. First, use a short-edged long drill bit 500 to drill from the front or back of the PCB board 400 to a depth of about 1.0 mm. Then use a long-edged long drill bit 600 to drill to a depth of half the thickness of the board + 0.5 mm to ensure that the drill can drill through. The specific depth will vary depending on the drill bit diameter. Finally, use the drill bit of the present invention to drill to a depth of half the thickness of the board + 0.6 mm to ensure that the previous step 411 can be drilled out and a step 411 with a smaller angle can be drilled out. Then repeat the same operation from the other side to complete the processing. The improved step 411 is obtained by using the drill bit and drilling method of the present invention. For details, refer to Figure 7 , normal drilling step 411 reference Figure 6 .

[0026] For plates with a thickness-to-diameter ratio of more than 35 times, a drill with an intermediate blade length is added between the short blade length drill 500 and the long blade length drill 600, that is, three drills with different blade lengths are used for processing on one side, and finally the drill bit of the present invention is used for processing to make the step 411 smoother.

[0027] For a PCB board 400 with a thickness-to-diameter ratio of more than 30 times the board thickness to the hole diameter, if the step 411 is removed by expanding the hole, the drill bit length-to-diameter ratio needs to be more than 40 times. For example, a 0.15mm diameter drill bit processes a 4.5mm board, and the blade length needs to be 6.0mm, because it is necessary to consider the drilling depth of 0.5mm + the board thickness of 4.5mm + the aluminum sheet of 0.20mm + the chip removal space of 0.8mm. However, a micro drill bit with a diameter of 0.15mm and a blade length of 6mm has a very low manufacturing qualification rate, and at the same time, the micro drill bit with a diameter of 0.15mm and a blade length of 6mm has a tool breakage rate of up to a few thousandths when drilling. For ultra-high aspect ratio drilling, assuming a board has 30,000 holes and each drill bit is limited to 100 holes, then each board requires 100 drill bits. Assuming the tool breakage rate is one in a thousand, one tool will break in every 10 boards, causing one board to be scrapped, and the scrap rate is as high as 10%. Ultra-high aspect ratio PCB boards of 400 generally have more layers, and the cost of a board is usually as high as tens of thousands of yuan, so such a high scrap rate leads to a high cost problem.

[0028] By using the drilling method of the present invention, even if a PCB board 400 with a thickness-to-diameter ratio of 40 times is processed, the required drill bit aspect ratio is no more than 30 times, because only half of the board thickness needs to be processed. For example, when a 6mm board is processed with a diameter of 0.15mm, the blade length only needs to be 4.5mm, the overlapping depth is 0.5mm + half of the board thickness 3mm + aluminum sheet 0.20mm + chip removal space 0.8mm, and the drill bit aspect ratio is about 30 times, and the drill bit manufacturing qualification rate and the tool breakage rate during drilling are greatly improved. However, since the drilling process requires turning the plate, there will be a misalignment after turning the plate, and the step 411 is inevitable, so the step 411 can be made gentle by improving the drill bit, reducing the problem of the step 411 causing the hole wall to be uneven, which is easy to cause dust plugging or the effect of copper separation in the hole after electroplating.

[0029] The present invention also provides an embodiment of a drilling method for drilling a PCB board 400 having a thickness-to-diameter ratio of 30 to 35 times, comprising: Step 1: Drill a first guide hole of a first depth on one side of the PCB board 400 using a short-blade long drill bit 500, wherein the first depth ranges from 0.5 mm to 1.0 mm; Step 2: Drill the first guide hole to a second depth using a long-edge long drill bit 600, wherein the second depth ranges from half the thickness of the PCB board 400 + 0.3 mm to 0.5 mm, to ensure that the drill can drill through; Step 3: Drilling the first guide hole to a third depth using the double-edged single-slot drill bit 700 as claimed in claims 1 to 6, wherein the third depth ranges from half the thickness of the PCB board 400 + 0.3 mm to 0.7 mm; Step 4: Drill a second guide hole of a first depth at a position corresponding to the first guide hole on the other side of the PCB board 400 using a short-blade long drill bit 500; Step 5: Drill the first guide hole to a second depth using the long-edge long drill bit 600 to ensure that the drill can drill through; Step 6: The first guide hole is drilled through the PCB board 400 by using the double-edged single-slot drill bit 700, and the step 411 of the drilled through hole 410 has a small inclination.

[0030] For a PCB board 400 with a thickness-to-diameter ratio of more than 35 times, step 7 is also included. Step 7 is implemented between step 1 and step 2. Step 7 includes: between drilling a first guide hole of a first depth on one side of the PCB board 400 by a short-blade long drill 500 and drilling the first guide hole to a second depth by a long-blade long drill 600, the first guide hole is also drilled to a fourth depth by a drill with an intermediate blade length so as to make the step 411 gentle, wherein the fourth depth is determined according to the board thickness.

[0031] For the short-blade drill 500, the blade length is relatively short, and it is usually used for shallow hole processing. Due to the short blade length, the resistance in the cutting process can be reduced, and the processing efficiency can be improved. However, because the short blade may be more susceptible to vibration and deviation during the processing, the processing accuracy may be limited to a certain extent. For the long-blade drill 600, the blade length is relatively long, which is suitable for deep hole processing and meets the needs of deep hole processing. Although the longer blade length may increase the resistance in the cutting process, the long blade design can better disperse the cutting force and improve the durability of the cutting edge, thereby improving the processing efficiency to a certain extent. Due to the longer blade length, the processing accuracy can be better controlled, and the processed workpiece surface is smoother and more accurate. The drill bit of the present invention has a smaller drill point angle 300, which can ensure that the step 411 formed by drilling is smoother, reducing the risk of dust plugging or copper separation after electroplating; the double-slot design at the front end helps to balance the cutting force and reduce the risk of tool breakage, and the single-slot design at the rear end helps to enhance the rigidity and reduce the inclination of the step 411 formed during drilling; the large core thickness design helps to enhance the rigidity of the drill bit, reduce the risk of tool breakage and reduce the step 411. In summary, the drill bit of the present invention can improve the unevenness of the hole wall caused by drilling, thereby improving dust plugging or copper separation after electroplating. The drilling method of the present invention makes full use of the characteristics of the short-blade long drill bit 500, the long-blade long drill bit 600, and the double-blade single-slot drill bit 700 to perform drilling on the ultra-high aspect ratio PCB board 400. The wall of the processed through hole 410 is smoother and is not easily blocked by dust or copper separation after electroplating.

[0032] The preferred embodiments of the present invention are specifically described above, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A double-edged single-groove drill bit, characterized in that: The drill body (200) comprises a drill tip and a drill tail end respectively at two ends thereof, the drill body (200) comprising a double groove section (210) and a single groove section (220) arranged in sequence from the drill tip to the drill tail end, the outer circumference of the drill body (200) being provided with a main spiral groove (211) spirally arranged from the drill tip to the drill tail end, the main spiral groove (211) spanning the double groove section (210) and the single groove section (220), the double groove section The outer peripheral wall of the drill bit (210) is provided with a spirally arranged auxiliary spiral groove (212), one end of the auxiliary spiral groove (212) extends to the drill tip, and the other end intersects with the main spiral groove (211) between the double-groove section (210) and the single-groove section (220), a drill core is formed between the main spiral groove (211) and the auxiliary spiral groove (212), and the ratio of the thickness of the drill core to the diameter of the drill body (200) varies in the range of 50% to 90%.

2. A double-edge single-slot drill bit according to claim 1, characterized in that: The secondary spiral groove (212) and the primary spiral groove (211) located on the double groove section (210) are arranged in a centrally symmetrical manner with respect to the axis of the drill body (200).

3. A double-edge single-slot drill bit according to claim 1, characterized in that: The drill tip is provided with a conical drill tip body, and the tip angle of the drill tip body is 60° to 120°.

4. A double-edge single-slot drill bit according to claim 3, characterized in that: The drill tip body is provided with two main cutting surfaces (201), two secondary cutting surfaces (202) connected to the long side edges of the main cutting surfaces (201), and a chisel edge (203) is provided at the connection between the two main cutting surfaces (201).

5. A double-edge single-flute drill bit according to claim 1, characterized in that: The helical angles of the main helical groove (211) and the secondary helical groove (212) located on the double-groove section (210) vary in the range of 35° to 55°.

6. A double-edge single-slot drill bit according to claim 1, characterized in that: The helical angle of the main helical groove (211) located on the single groove section (220) varies in the range of 45° to 60°.

7. A drilling method, characterized in that: Used for drilling holes in a PCB board, the drilling method comprises: Drilling a first guide hole of a first depth on one side of the PCB board (400) using a short-blade long drill bit (500); Drilling the first guide hole to a second depth using a long-edge long drill bit (600); Drilling the first guide hole to a third depth using the double-edge single-flute drill bit (700) as claimed in claims 1 to 6; Drilling a second guide hole of a first depth at a position corresponding to the first guide hole on the other side of the PCB board (400) using a short-blade long drill bit (500); Drilling the first guide hole to a second depth using a long-edge long drill bit (600); The first guide hole is drilled through the PCB board (400) using the double-edged single-slot drill bit (700).

8. A drilling method according to claim 7, characterized in that: The method of drilling a first guide hole of a first depth on one side of the PCB board (400) by using a short-blade long drill bit (500) and drilling the first guide hole to a second depth by using a long-blade long drill bit (600) also includes drilling the first guide hole to a fourth depth by using a medium-blade long drill bit.

9. A drilling method according to claim 7, characterized in that: The short-blade long drill bit (500) is used to drill a first guide hole of a first depth on one side of the PCB board (400), wherein the first depth ranges from 0.5 mm to 1.0 mm.

10. A drilling method according to claim 7, characterized in that: The first guide hole is drilled to a third depth by using the double-edged single-slot drill bit (700) as claimed in claims 1 to 6, wherein the third depth ranges from half the thickness of the PCB board (400) + 0.3 mm to 0.7 mm.

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