A new type of drill bit

Abstract

The present invention is applicable to the field of PCB micro-drill manufacturing, and provides a new type of drill bit, which includes a drill shank and a working part. The rear end of the working part is connected to the drill shank. The working part includes two cutting edges and chip flutes corresponding to the two cutting edges and spirally distributed on the outer peripheral surface of the working part. The spiral angle of the chip flutes is 10°-25°. Each cutting edge is correspondingly provided with a first flank and a second flank. The intersection line of the first flank and the second flank deviates from the axis position of the working part. The projection of the cutting edge on the plane perpendicular to the central axis of the working part is a curve without inflection points. The ratio of the distance from the highest point of the curve to the intersection line to the distance from the lowest point of the curve to the intersection line is 2-4:1, and the ratio of the core thickness at the front end of the working part to the diameter of the working part is 1:5-12. The new type of drill bit provided by the present invention can greatly improve the problem of copper nodules in the holes during the drilling process of high-frequency material circuit boards containing PTFE.

Description

Technical Field

[0001] The present invention belongs to the field of manufacturing PCB micro-drills, and particularly relates to a new type of drill bit. Background Art

[0002] With the rapid development of the communication industry, high-frequency material circuit boards are increasingly used, mainly widely used in antennas and power amplifiers. Most of the drilling of high-frequency materials is relatively easy to process, but the drilling of special PTFE materials (polytetrafluoroethylene) or high-frequency materials containing a certain proportion of PTFE materials is very difficult. The main difficulty lies in the particularity of PTFE materials (polytetrafluoroethylene). Polytetrafluoroethylene is a typical soft and weak polymer with relatively small intermolecular attraction, low stiffness, hardness, and strength, and it will deform under stress. The mechanical properties of polytetrafluoroethylene are relatively soft and it has a very low surface energy, so the drilling process is very difficult. The main quality problems are manifested in that the hole glass fibers in the hole and a small amount of resin at the hole opening are not cut cleanly, resulting in a large number of copper nodules after copper plating in the hole, seriously affecting the function of electronic products or causing a high scrap rate in the circuit board manufacturing process, which is an urgent problem to be solved in the entire circuit board industry. At the same time, due to the high-frequency material circuit board containing PTFE, the drill bit is extremely easy to wear during processing, resulting in high processing costs. Summary of the Invention

[0003] The present invention aims to solve at least one of the above technical problems, and provides a new type of drill bit that can greatly improve the problem of copper nodules in the hole during the drilling process of high-frequency material circuit boards containing PTFE.

[0004] The technical solution of the present invention is: a new type of drill bit, including a drill shank and a working part. The rear end of the working part is connected to the drill shank. The working part includes two cutting edges and chip flutes corresponding to the two cutting edges and spirally distributed on the outer peripheral surface of the working part. The spiral angle of the chip flutes is 10° - 25°. Each cutting edge is correspondingly provided with a first flank face and a second flank face. The intersection line of the first flank face and the second flank face deviates from the axis position of the working part. The projection of the cutting edge on a plane perpendicular to the central axis of the working part is a curve without inflection points. The ratio of the distance from the highest point of the curve to the intersection line to the distance from the lowest point of the curve to the intersection line is 2 - 4:1, and the ratio of the core thickness at the front end of the working part to the diameter of the working part is 1:5 - 12.

[0005] Optionally, the ratio of the distance from the highest point of the curve to the intersection line to the distance from the lowest point of the curve to the intersection line is 2.4 - 3.2:1, and the ratio of the core thickness at the front end of the working part to the diameter of the working part is 1:8 - 10.

[0006] Optionally, along the direction from the front end to the rear end of the working part, the core thickness gradually increases.

[0007] Optionally, along the direction from the front end to the rear end of the working part, the width of the chip discharge groove gradually increases.

[0008] Optionally, the working part further includes a cutting edge lobe located between the two chip discharge grooves. The cutting edge lobe includes a land and a flank. The land is located in front of the flank along the rotation direction of the drill bit, and the land is adjacent to the chip discharge groove. The height difference between the flank and the land increases as it gets closer to the flank along the rotation direction of the drill bit.

[0009] Optionally, the ratio of the height difference between the flank and the land on the side close to the land to the height difference between the flank and the land on the side far from the land is 2:1.

[0010] Optionally, the distance from the flank on the side far from the land to the axis of the working part is 80%-95% of the radius of the working part.

[0011] A novel drill bit provided by the present invention optimizes the helix angle of the chip discharge groove, the core thickness at the front end of the drill bit, and the structure of the cutting edge. When used for processing a high-frequency material circuit board containing PTFE, the drill bit can quickly cut into the circuit board substrate. Among them, the design of the small helix angle of the chip discharge groove can reduce the wear of the cutting edge surface. The projection of the cutting edge is a curve without inflection points, and the design that limits the ratio of the highest point to the lowest point of the curve makes the drill tip sharp, ensuring excellent processing performance of the drill bit. By controlling the core thickness at the front end of the drill bit, the chisel edge is shortened, which can reduce the influence of drill tip wear on the cutting ability. Through the combination of the three, the problems of internal hole burrs and unclean resin cutting at the hole opening that occur when the existing drill bit processes a high-frequency material circuit board containing PTFE are solved, resulting in a large number of copper nodules after copper plating in the hole, and the quality of the holes obtained by drilling the high-frequency material circuit board containing PTFE is guaranteed. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0013] Figure 1 It is a front view of a novel drill bit provided by an embodiment of the present invention;

[0014] Figure 2 It is a front view of a novel drill bit provided by an embodiment of the present invention;

[0015] Figure 3 It is a front view of the control group drill bit in Embodiment 1 of the present invention;

[0016] Figure 4 It is a schematic diagram of the orifice quality of the first machined hole after copper plating in the experimental group of Example 1;

[0017] Figure 5 It is a schematic diagram of the orifice quality of the twentieth machined hole after copper plating in the experimental group of Example 1;

[0018] Figure 6 It is a schematic diagram of the partial inner-hole quality of the first machined hole after copper plating in the experimental group of Example 1;

[0019] Figure 7 It is a schematic diagram of the partial inner-hole quality of the twentieth machined hole after copper plating in the experimental group of Example 1;

[0020] Figure 8 It is a schematic diagram of the orifice quality of the first machined hole after copper plating in the control group of Example 1;

[0021] Figure 9 It is a schematic diagram of the orifice quality of the twentieth machined hole after copper plating in the control group of Example 1;

[0022] Figure 10 It is a schematic diagram of the inner-hole quality of the first machined hole after copper plating in the control group of Example 1;

[0023] Figure 11 It is a schematic diagram of the inner-hole quality of the twentieth machined hole after copper plating in the control group of Example 1;

[0024] In the figure, 1 - working part, 2 - cutting edge, 21 - first flank face, 22 - second flank face, 23 - intersection line of the first flank face and the second flank face, 3 - chip flute, 4 - blade lobe, 41 - land, 42 - blade back, 2' - cutting edge of the drill bit in the control group, 41' - land of the drill bit in the control group, 42' - blade back of the drill bit in the control group, c - width of the chip flute, d1 - distance from the lowest point of the curve to the intersection line, d2 - distance from the highest point of the curve to the intersection line, d - front core thickness of the working part. Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] It should be noted that the terms "arrange" and "connect" should be understood in a broad sense. For example, it can be a direct arrangement, installation, connection, or can be indirectly arranged and connected through intermediate components and intermediate structures.

[0027] In addition, in the embodiments of the present invention, if there are orientations or positional relationships indicated by "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., they are based on the orientations or positional relationships shown in the drawings or the conventional placement states or usage states. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the structures, features, devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more than two.

[0028] In the various specific technical features and embodiments described in the specific implementation manners, they can be combined in any appropriate manner without conflict. For example, different embodiments can be formed by combining different specific technical features / embodiments. To avoid unnecessary repetition, various possible combination manners of the specific technical features / embodiments in the present invention will not be described separately.

[0029] As Figure 1 and Figure 2 shown, a new type of drill bit provided by the embodiments of the present invention is used for drilling a circuit board made of high-frequency material containing PTFE, and the aperture of the processed hole is greater than 0.5 mm. In the circuit board made of high-frequency material containing PTFE, the PTFE material has a relatively soft property and does not belong to plastic materials. After being laminated with glass fiber, the high-frequency material circuit board has the characteristics of being soft and tough, and it is difficult to drill it. During processing, it is necessary to ensure the quality of the processed hole as much as possible while minimizing the wear amount of the drill bit cutting edge and the wear amount of the drill bit body. Based on this, the new type of drill bit in this embodiment includes a drill shank and a working part 1. The rear end of the working part 1 is connected to the drill shank. The working part 1 includes two cutting edges 2 and two chip flutes 3. The two chip flutes 3 correspond to the two cutting edges 2 and are spirally distributed on the outer peripheral surface of the working part 1. Among them, the spiral angle of the chip flute 3 is 10° - 25°. Each cutting edge 2 is correspondingly provided with a first flank 21 and a second flank 22. The first flank 21 is adjacent to the cutting edge 2, and the second flank 22 is adjacent to the other chip flute 3. The intersection line 23 of the first flank 21 and the second flank 22 deviates from the axis position of the working part 1. The projection of the cutting edge 2 on the plane perpendicular to the central axis of the working part 1 is a curve without inflection points. The ratio of the distance d2 from the highest point of the curve to the intersection line 23 to the distance d1 from the lowest point of the curve to the intersection line 23 is 2 - 4:1, and the ratio of the core thickness d at the front end of the working part 1 to the diameter of the working part 1 is 1:5 - 12.

[0030] In this embodiment, the limitation of the existing processing idea is broken through. The wear of the cutting edge surface is reduced by significantly decreasing the helix angle. The wear of the cutting edge 2 is reduced by controlling the structure of the cutting edge 2 (the ratio of the distance d2 from the highest point of the curve to the intersection line 23 to the distance d1 from the lowest point of the curve to the intersection line 23 is 2 - 4:1), so as to ensure the sharpness of the cutting edge 2. By optimizing the ratio between the core thickness at the front end of the working part 1 and the working part 1, the length of the chisel edge is shortened to reduce the wear of the drill tip. Starting from the three aspects of reducing the cutting edge surface, the cutting edge 2 and the wear of the drill tip, when drilling a circuit board made of high-frequency material containing PTFE, the drill tip can quickly drill into the circuit board substrate and cut off the PTFE material, thus effectively solving the problems of burrs in the hole and unclean resin cutting at the hole opening during the processing of the existing drill bit, which leads to a large number of copper nodules formed after copper plating in the hole, and ensuring the quality of the holes obtained by drilling the circuit board made of high-frequency material containing PTFE.

[0031] In some embodiments, the ratio of the distance d2 from the highest point of the curve to the intersection line 23 to the distance d1 from the lowest point of the curve to the intersection line 23 is 2.4 - 3.2:1, and the ratio of the core thickness d at the front end of the working part 1 to the diameter of the working part 1 is 1:8 - 10. Preferably, the ratio of the distance d2 from the highest point of the curve to the intersection line 23 to the distance d1 from the lowest point of the curve to the intersection line 23 is 2.5:1, and the ratio of the core thickness d at the front end of the working part 1 to the diameter of the working part 1 is 1:8.

[0032] In some embodiments, the helix angle of the chip flute 3 is 18°. Among them, the drill point angle of this drill bit can be the same as that of a conventional drill needle, ensuring that the drill bit can be ground without being affected after use and can be reused.

[0033] In some embodiments, along the direction from the front end to the rear end of the working part 1, the core thickness gradually increases. That is, along the direction from the front end to the rear end of the working part 1, the core thickness of the working part 1 has a taper structure to improve the rigidity strength of the drill bit. Since the general drilling of medium and large sizes has a relatively thick stacked board, it is necessary to ensure that the drill bit has sufficient rigidity and cooperate with the sharp chip cutting ability in the above-mentioned tip structure. On the premise of ensuring excellent processing performance of the drill bit, the drill bit works reliably and stably.

[0034] In some embodiments, such as Figure 2As shown, along the direction from the front end to the rear end of the working part 1, the width c of the chip removal groove 3 gradually increases. That is, at the rear end of the working part 1, a design of increasing the width c of the chip removal groove 3 is adopted to form a wider chip removal space, greatly enhancing the chip removal ability of the drill bit. This ensures that during the processing of a high-frequency material circuit board containing PTFE, chips can be quickly discharged, improving the smoothness of chip removal, thus solving the problem of resin dissolving the tool in drilling processing and ensuring the quality of the hole wall. The problem of resin dissolving the tool refers to: because the PTFE material is very soft, it will mix with copper chips and other fillers during processing to form a substance sticking to the side of the drill bit or the root of the chip removal groove 3, resulting in chip clogging.

[0035] In practical applications, when using a grinding wheel to grind and process the chip removal groove 3, the width c of the chip removal groove 3 is increased by controlling the width of the grinding wheel and adjusting the grinding angle of the grinding wheel.

[0036] In some embodiments, as Figure 1 shown, the working part 1 further includes a cutting lip 4 located between two chip removal grooves 3. The cutting lip 4 includes a land 41 and a flank 42. The cutting lip 4 refers to the part of the working part 1 other than the two chip removal grooves 3. The land 41 is located in front of the flank 42 along the rotation direction of the drill bit, and the land 41 is adjacent to the corresponding chip removal groove 3, that is, the wall surface of the chip removal groove 3 facing the rotation direction of the drill bit intersects with the land 41, and along the rotation direction of the drill bit, the closer to the flank 42, the greater the height difference (along the radial direction of the working part 1) between the flank 42 and the land 41, so that the gap between the flank 42 and the hole wall is larger closer to the land 41. Through such a design, the friction between the working part 1 and the hole wall can be reduced, thereby reducing the temperature of the working part 1 during the processing. During the drilling process of the drill bit, the land 41 can play a supporting role for the working part 1 and can stabilize the rotation of the working part 1 in the hole.

[0037] In some embodiments, the ratio of the height difference between the flank 42 and the land 41 on the side close to the land 41 to the height difference between the flank 42 and the land 41 on the side far from the land 41 is 2:1.

[0038] In some embodiments, the distance from the flank 42 on the side far from the land 41 to the axis of the working part 1 is 80%-95% of the radius of the working part 1. By optimizing the space size between the flank 42 and the wall of the processed hole, the heat dissipation efficiency can also be improved, and it can ensure that the working part has sufficient strength. Preferably, the distance between the axis of the working part 1 and the flank 42 on the side far from the land 41 is 85% of the radius of the working part 1.

[0039] Specifically, along the rotation direction of the drill bit, the height difference between the flank 42 and the land 41 changes in a stepped progressive manner, that is, the projection of the flank 42 on the plane perpendicular to the central axis of the working part 1 is a stepped line; or, the projection of the flank 42 on the plane perpendicular to the central axis of the working part 1 is an arc.

[0040] A novel drill bit provided by an embodiment of the present invention optimizes the helix angle of the chip flute 3, the core thickness at the front end of the drill bit, and the structure of the cutting edge 2. When used for processing a high-frequency material circuit board containing PTFE, the drill bit can quickly cut into the circuit board substrate. Among them, the design of the small helix angle of the chip flute 3 can reduce the wear of the cutting edge surface. The projection of the cutting edge 2 is a curve without inflection points, and the design that limits the ratio of the highest point to the lowest point of the curve makes the drill tip sharp, ensuring excellent machining performance of the drill bit. By controlling the core thickness at the front end of the drill bit, the chisel edge is shortened, which can reduce the influence of drill tip wear on the cutting ability. Through the combination of the three, the problems of internal hole burrs and unclean resin cutting at the hole opening that occur when the existing drill bit processes a high-frequency material circuit board containing PTFE are solved, resulting in a large number of copper nodules after copper plating in the hole, and the quality of the holes obtained by drilling the high-frequency material circuit board containing PTFE is guaranteed.

[0041] In order to further understand the present invention, the following will be described in detail with specific embodiments.

[0042] Example 1,

[0043] Experimental group: The drill bit structure of the present invention, wherein the helix angle of the chip flute 3 is 18°, the ratio of the distance d2 from the highest point of the curve to the intersection line 23 to the distance d1 from the lowest point of the curve to the intersection line 23 is 2.5:1, and the ratio of the core thickness d at the front end of the working part 1 to the diameter of the working part 1 is 1:8. In the direction from the front end to the rear end of the working part, the width of the chip flute gradually increases, and the core thickness gradually increases. The height difference between the cutting edge back 42 and the cutting edge band 41 on the side close to the cutting edge band 41 and the height difference between the cutting edge back 42 and the cutting edge band 41 on the side far from the cutting edge band 41 is 2:1, and the distance between the axis of the working part 1 and the cutting edge back 42 on the side far from the cutting edge band 41 is 85% of the radius of the working part 1;

[0044] Control group: In the drill bit of the control group, the helix angle of the chip flute is 27°. In the direction from the front end to the rear end of the working part, the width of the chip flute remains unchanged, and the height difference between the entire cutting edge back 42' and the cutting edge band 41' remains unchanged (see Figure 3 ). Specifically, the drill bit of the control group is the existing 129-type drill bit.

[0045] The drill bits of the experimental group and the control group both have a diameter of 3.175 mm. The drill bits of the experimental group and the control group are respectively used to drill two identical circuit boards containing high-frequency materials with PTFE under the same processing conditions, and the holes obtained by processing are copper-plated. Among them, the hole mouth qualities of the first hole and the twentieth hole obtained by processing and copper-plating in the experimental group are as Figure 4 and Figure 5 shown, and the hole mouth qualities of the first hole and the twentieth hole obtained by processing and copper-plating in the control group are asFigure 8 and Figure 9 As shown in Figure 9 , it can be seen by comparison that the quality of the hole opening of the holes processed in the experimental group is better than that of the control group;

[0046] The internal quality of the first hole and the twentieth hole in the experimental group is as Figure 6 and Figure 7 shown ( Figure 6 and Figure 7 Figure 6 and Figure 7 are only part of the cross-sectional views of the first hole and the twentieth hole), and the internal quality of the first hole and the twentieth hole in the control group is as Figure 10 and Figure 11 shown. It can be seen by comparison that the internal quality of the holes processed in the experimental group is better than that of the control group; and by comparing the hole opening quality and the internal quality of the first hole and the twentieth hole, there is little difference between the hole opening quality and the internal quality of the first hole and the twentieth hole in the experimental group, while there is a large difference between the hole opening quality and the internal quality of the first hole and the twentieth hole in the control group, and a large number of copper tumors are formed after copper plating on the twentieth hole. Thus, it can be known that the drill bit of the present invention has a longer service life compared with the existing drill bits.

[0047] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A new type of drill bit, characterized in that, the new type of drill bit is used for drilling a high-frequency material circuit board containing PTFE, and includes a drill shank and a working part. The rear end of the working part is connected to the drill shank. The working part includes two cutting edges and chip removal grooves corresponding to the two cutting edges and spirally distributed on the outer peripheral surface of the working part. The spiral angle of the chip removal grooves is 10°-25°. Each cutting edge is correspondingly provided with a first flank and a second flank. The intersection line of the first flank and the second flank deviates from the axis position of the working part. The projection of the cutting edge on a plane perpendicular to the central axis of the working part is a curve without inflection points. The ratio of the distance from the highest point of the curve to the intersection line to the distance from the lowest point of the curve to the intersection line is 2-4:1, and the ratio of the core thickness at the front end of the working part to the diameter of the working part is 1:5-12.

2. The new type of drill bit according to claim 1, characterized in that, the ratio of the distance from the highest point of the curve to the intersection line to the distance from the lowest point of the curve to the intersection line is 2.4-3.2:1, and the ratio of the core thickness at the front end of the working part to the diameter of the working part is 1:8-10.

3. The new type of drill bit according to claim 1, characterized in that, along the direction from the front end to the rear end of the working part, the core thickness gradually increases.

4. The new type of drill bit according to claim 1, characterized in that, along the direction from the front end to the rear end of the working part, the width of the chip removal groove gradually increases.

5. The new type of drill bit according to claim 1, characterized in that, the working part further includes a cutting lip located between the two chip removal grooves. The cutting lip includes a land and a flank. The land is located in front of the flank along the rotation direction of the drill bit, and the land is adjacent to the chip removal groove. The height difference between the flank and the land gradually increases along the rotation direction of the drill bit.

6. The new type of drill bit according to claim 5, characterized in that, the ratio of the height difference between the flank and the land on the side close to the land to the height difference between the flank and the land on the side far from the land is 2:

1.

7. The new type of drill bit according to claim 5, characterized in that, the distance from the flank on the side far from the land to the axis of the working part is 80%-95% of the radius of the working part.

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