Circuit board metalization half-hole processing tool and half-hole processing process

Abstract

The application discloses a circuit board metalization half-hole machining tool and a half-hole machining process, and relates to the technical field of circuit board half-hole machining. The application discloses a circuit board metalization half-hole machining tool and a half-hole machining process, and relates to the technical field of circuit board half-hole machining. The tool seat is provided with a cutting edge structure coaxially arranged at the bottom of the tool seat, and a cleaning structure is arranged between the tool seat and the cutting edge structure, so that the cutting chips can be removed in time during the cutting process. The cutting edge structure comprises a first cutter assembly coaxially arranged at the bottom of the tool seat, and a second cutter assembly coaxially arranged at the bottom of the first cutter assembly. The first cutter assembly and the second cutter assembly are connected and provided with the cleaning structure. The cutting edge structure composed of the first cutter assembly and the second cutter assembly with opposite spiral directions can avoid unevenness and hole wall scratches during cutting, ensure sufficient finishing of the half-hole wall and the edge of the groove, reduce the surface roughness, and meet the high-precision machining requirement.

Description

Technical Field

[0001] This invention relates to the field of circuit board half-hole processing technology, specifically to the cutting tools and half-hole processing technology for metallized circuit boards. Background Technology

[0002] In the PCB manufacturing process, the processing quality of metallized half-holes directly affects the conductivity, mechanical strength, and reliability of the PCB. Currently, the main process for processing metallized half-holes on circuit boards is drilling, metallization, and router finishing. This involves first drilling a complete through-hole on the PCB, then metallizing the hole wall through processes such as chemical copper plating and electroplating, and finally removing part of the hole wall and surrounding copper layer by router finishing, forming a semi-circular metallized half-hole structure.

[0003] In the aforementioned processing, the performance of the machining tool determines the quality of the metallized half-hole machining. However, most existing finishing tools employ a single-component design with a single helical direction. During cutting, the cutting force is concentrated, which easily leads to skew, especially when machining thinner PCB boards or high-hardness copper layers. This can result in uneven cutting, scratches on the hole walls, and an inability to adequately finish the groove edges and half-hole walls, leading to high surface roughness that does not meet the requirements of high-precision machining. Summary of the Invention

[0004] The purpose of this invention is to provide a tool and process for machining half-holes in circuit board metallization. By using a cutting edge structure composed of a first cutting tool assembly and a second cutting tool assembly with opposite spiral directions, problems such as unevenness and scratches on the hole wall can be avoided during cutting. This ensures that the edge of the groove and the half-hole wall are fully finished, reducing the surface roughness of the machined surface and meeting the requirements of high-precision machining.

[0005] The above-mentioned optimized structure of the present invention is achieved through the following technical solution: a metallization half-hole machining tool for circuit boards, including a tool holder; A cutting edge structure, wherein the cutting edge structure is coaxially disposed at the bottom of the tool holder; It also includes a cleaning structure, which is located between the tool holder and the cutting edge structure, and can realize the timely removal of chips during the cutting process; The blade structure includes a first blade assembly, which is coaxially disposed at the bottom of the blade holder; The second blade assembly is coaxially disposed at the bottom of the first blade assembly, and the spiral direction of the first blade assembly is opposite to that of the second blade assembly. The cleaning structure is provided at the connection between the first blade assembly and the second blade assembly.

[0006] In some embodiments, the first blade assembly includes a first blade body, which is coaxially disposed at the bottom of the blade holder; Multiple first main cutting edges are arranged in a spiral shape around the first blade body; Multiple first secondary blades are spirally arranged around the first blade body; and the first secondary blades are located between two adjacent first main blades. Multiple first guide grooves are provided between multiple first main cutting edges and multiple first secondary cutting edges.

[0007] In some embodiments, the second blade assembly includes a second blade body, which is coaxially disposed at the bottom of the first blade body; Multiple second main cutting edges are arranged in a spiral around the second blade body; Multiple secondary blades are spirally arranged around the second blade body; and the secondary blades are located between two adjacent second primary blades. Multiple second guide grooves are provided between multiple second main cutting edges and multiple second secondary cutting edges.

[0008] In some embodiments, a plurality of second main cutting edges are respectively connected to the bottom of a plurality of first main cutting edges, a plurality of second secondary cutting edges are respectively connected to the bottom of a plurality of first secondary cutting edges, and a plurality of second guide grooves are respectively connected to a plurality of first guide grooves.

[0009] In some embodiments, the helical direction of the second primary blade is opposite to that of the first primary blade, and the helical direction of the second secondary blade is opposite to that of the first secondary blade.

[0010] In some embodiments, the angle between the first main blade, the first secondary blade and the axis of the first blade body is 5°-10°, and the angle between the second main blade, the second secondary blade and the axis of the second blade body is 5°-10°.

[0011] In some embodiments, the helix angle of the first main blade, the first secondary blade, the second main blade, and the second secondary blade is 25° to 35°, and the surfaces of the first main blade, the first secondary blade, the second main blade, and the second secondary blade are coated with a titanium nitride coating.

[0012] In some embodiments, the cleaning structure includes a cleaning blind hole that coaxially passes through the tool holder and the first tool body and extends to the top of the second tool body; Multiple cleaning ports are arranged in a ring at the bottom of the cleaning blind hole and are respectively connected to the connection points of multiple first guide grooves and multiple second guide grooves.

[0013] A process for metallizing half-holes on a circuit board includes the following steps: Step S1: Drill through holes on the PCB board for forming metallized half-holes, wherein the diameter of the through holes is 0.8mm-1.0mm; Step S2: A copper layer is deposited on the surface of the hole wall of the through hole using a combination of chemical copper plating and electroplating thickening process to form a conductive circuit; Step S3: Fabricate outer layer circuitry and outer layer circuitry via rings on the surface of the PCB board; Step S4: Use a coarse router cutter to create a router groove in the router groove forming area of ​​the PCB board along the pre-router line. The router groove penetrates the through hole to initially form a metallized half hole. Step S5: Adjust the cutting angle of the tool to 30°-45° and perform fine finishing along the forming line of the groove. During the fine finishing process, the tool holder moves in a wave-shaped curve, and at the same time, the cleaning structure continuously removes chips to prevent the copper foil on the hole wall from lifting and the burrs from remaining. Step S6: Inspect the size and wall quality of the metallized half-holes on the finished PCB board. Once the inspection is passed, the metallized half-holes are processed.

[0014] In some embodiments, step S5 includes the following steps: Step S51: Align the connection point between the first blade assembly and the second blade assembly with the bottom of one end of the hole wall to be finished; Step S52: Rotate the cutting tool to refine the wall of the hole to be refined, and lift the cutting tool so that the connection between the first cutting tool assembly and the second cutting tool assembly is flush with the top of the end of the wall of the hole to be refined. Step S53: Move the cutting tool to the other end of the hole wall to be repaired. During the movement, make the tool holder move up and down back and forth synchronously until the connection between the first tool assembly and the second tool assembly is flush with the bottom or top of the other end of the hole wall to be repaired. The moving height of the tool holder is less than the height of the hole wall to be repaired. Step S54: Stop moving the cutting tool, and move the cutting tool up or down to complete the finishing of the hole wall to be finished.

[0015] The above-described technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: (1) The first and second cutting tool components of the present invention adopt opposite spiral directions. When rotating synchronously, the first and second cutting tool components perform reverse cutting. After the first cutting tool component completes the initial finishing, the second cutting tool component performs supplementary cutting from the opposite direction, making the cutting force distribution more uniform. This can effectively eliminate burrs and uneven parts generated by unidirectional cutting, reduce the pulling of the copper layer on the hole wall during the cutting process, and prevent the copper skin from lifting. At the same time, through the cleaning structure, the cleaning medium enters the connection between the first guide groove and the second guide groove through the cleaning blind hole and the cleaning port, and quickly discharges the chips from the cutting area, preventing the chips from accumulating in the half hole. This reduces the frictional resistance between the tool and the chips and the hole wall, and avoids defects such as burrs and flashes on the edge of the groove and lifting and falling off of the copper skin on the hole wall caused by uneven cutting force. This ensures that the half hole wall is flat and smooth, and improves the surface quality of the machined surface. It can also reduce the tool vibration caused by chip extrusion, ensure the stability of the cutting trajectory, improve the machining accuracy, avoid chip wear on the cutting edge, and extend the tool life.

[0016] (2) The cutting angle of the tool is designed to be 30°-45°, which can be flexibly adjusted according to the processing material to achieve efficient cutting of resin substrate and copper layer, reduce cutting resistance and tool wear; the included angle of the axis is designed to be 5°-10° to ensure that the contact area between the tool and the processing surface is moderate, avoid stress concentration and chipping caused by stress, and reduce frictional resistance; the helix angle is designed to be 25°-35° to make the cutting trajectory more stable, improve chip removal efficiency and processing surface quality; the titanium nitride coating has high hardness and wear resistance, which can reduce the friction coefficient between the tool and the processing material, reduce tool sticking, extend tool life, and improve the smoothness of the processing surface to ensure consistency of batch processing.

[0017] (3) The present invention adopts a bidirectional finishing method to offset the stress generated by single-direction cutting, reduce processing deformation, avoid cutting dead angles, and improve processing accuracy; the wave-shaped moving trajectory increases the contact area between the cutting edge and the processing surface, improves the finishing effect, and reduces cutting edge wear; the coordinated chip removal ensures that chips are removed in time during the finishing process, avoids defects, and further improves processing accuracy and efficiency; and through single bidirectional finishing, copper wire and glass fiber can have sufficient force points at the hole wall, thereby avoiding wire pulling caused by avoidance, and finishing can be achieved in one go, thereby improving finishing efficiency. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the cutting tool of the present invention; Figure 2 This is a structural schematic diagram of the cutting tool of the present invention from another perspective; Figure 3 This is a cross-sectional view of the cutting tool of the present invention; Figure 4 This is a process flow diagram of the present invention; Figure 5 This is a top view of the tool path corresponding to the finishing steps of the present invention; Figure 6 This is a front view of the tool path corresponding to the finishing steps of this invention.

[0020] In the diagram: 1. Tool holder; 2. Cleaning structure; 21. Cleaning blind hole; 22. Cleaning port; 3. First tool assembly; 31. First tool body; 32. First main cutting edge; 33. First secondary cutting edge; 34. First guide groove; 4. Second tool assembly; 41. Second tool body; 42. Second main cutting edge; 43. Second secondary cutting edge; 44. Second guide groove. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, 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 invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 invention according to the specific circumstances.

[0025] refer to Figure 1-3 The circuit board metallization semi-hole machining tool includes a tool holder 1, a cutting edge structure, and a cleaning structure 2. The tool holder 1 is the mounting base component for the tool, used to connect with the spindle of the machining equipment, providing stable support and power transmission for the entire tool. The shape design of the tool holder 1 is adapted to the clamping structure of conventional machining equipment, ensuring coaxiality and rotational stability after installation. The tool holder 1 can be made of cemented carbide, which has high hardness, wear resistance, and bending strength, and can withstand the cutting force and vibration during high-speed rotation cutting, preventing deformation or damage to the tool holder. The cutting edge structure is coaxially located at the bottom of the tool holder 1 and is used for cutting and finishing operations of metallized half-holes and router slots on PCB boards. The cleaning structure 2 is located between the tool holder 1 and the cutting edge structure, which can remove the chips generated during the cutting process in a timely manner, preventing chip accumulation from affecting the processing quality. The cutting edge structure includes a first cutting edge assembly 3 and a second cutting edge assembly 4. The first cutting edge assembly 3 is coaxially located at the bottom of the tool holder 1 and mainly undertakes cutting and finishing operations. The second cutting edge assembly 4 is coaxially located at the bottom of the first cutting edge assembly 3 and mainly undertakes cutting and finishing operations. The spiral direction of the first cutting edge assembly 3 is opposite to that of the second cutting edge assembly 4. The cleaning structure 2 is provided at the connection between the first cutting edge assembly 3 and the second cutting edge assembly 4 to ensure that the chips generated during cutting can be quickly guided into the cleaning structure 2 for timely removal.

[0026] The first cutting tool assembly 3 includes a first cutting tool body 31, multiple first main cutting edges 32, multiple first secondary cutting edges 33, and multiple first guide grooves 34. All components are integrally molded to ensure structural stability and cutting reliability. The first cutting tool body 31 is coaxially mounted at the bottom of the tool holder 1, serving as the mounting base for the first cutting tool assembly 3. It maintains high-precision coaxiality with the tool holder 1 to avoid vibration during cutting. The first cutting tool body 31 may be a cylindrical structure, with multiple first main cutting edges 32 spirally arranged around it and evenly distributed. 1. In the circumferential direction, it undertakes the main cutting operation and can quickly remove the machining allowance remaining after rough milling; the number of first main cutting edges 32 can be 3-4, and the cutting edge thickness of the first main cutting edge 32 gradually decreases from the root to the tip, forming a sharp cutting edge, which is convenient for cutting into the PCB substrate and copper layer and reducing cutting resistance; the tip of the first main cutting edge 32 is provided with a chamfer structure, and the chamfer angle is 45° to prevent the cutting edge from chipping and reduce burrs generated during the cutting process; multiple first secondary cutting edges 33 are arranged in a spiral shape. On the first cutting body 31, a first secondary cutting edge 33 is located between two adjacent first main cutting edges 32. The number of first secondary cutting edges 33 is equal to the number of first main cutting edges 32, ensuring that there is one first secondary cutting edge 33 between each adjacent first main cutting edge 32. The first secondary cutting edge 33 is smaller than the cutting edge width of the first main cutting edge 32, and is used to perform preliminary finishing on the surface after cutting by the first main cutting edge 32, remove residual burrs, reduce surface roughness, and assist in the removal of chips; the cutting edge of the first secondary cutting edge 33 is... The sharpness is higher than that of the first main cutting edge 32, which can effectively remove the burrs and chips remaining after the first main cutting edge 32 cuts, thus improving the machining quality. Multiple first guide grooves 34 are respectively arranged between multiple first main cutting edges 32 and multiple first secondary cutting edges 33. The first guide grooves 34 have a spiral structure, and their spiral direction is consistent with the spiral direction of the first main cutting edge 32 and the first secondary cutting edge 33. They serve as chip discharge channels and can guide the chips generated by the cutting of the first main cutting edge 32 and the first secondary cutting edge 33 to achieve rapid chip discharge.

[0027] In some embodiments, the second cutting tool assembly 4 includes a second cutting tool body 41, a plurality of second main cutting edges 42, a plurality of second auxiliary cutting edges 43, and a plurality of second guide grooves 44. Its overall structure is adapted to the first cutting tool assembly 3 to ensure the continuity of cutting and finishing operations. The second cutting tool body 41 is coaxially disposed at the bottom of the first cutting tool body 31 and integrally formed with the first cutting tool body 31 to ensure a fixed connection and avoid the formation of steps, thereby avoiding the formation of cutting dead angles. At the same time, it remains coaxial with the tool holder 1 and the first cutting tool body 31 to ensure a stable cutting trajectory. The outer diameter of the second cutting tool body 41 is equal to the outer diameter of the first cutting tool body 31 to ensure uniform contact between the tool and the half-hole and the groove during the cutting process and to avoid the formation of steps. The plurality of second main cutting edges 42 are spirally arranged around the second cutting tool body 41 and are evenly distributed in the circumferential direction of the second cutting tool body 41. The number of second main cutting edges 42 is equal to the number of second main cutting edges 43. The number of first main cutting edges 32 is equal, and they work together to complete secondary cutting, further removing residual machining allowance. The cutting edge width and thickness of the second main cutting edge 42 are exactly the same as those of the first main cutting edge 32, ensuring consistent cutting performance. Multiple second auxiliary cutting edges 43 are spirally arranged around the second cutter body 41, and the second auxiliary cutting edges 43 are located between two adjacent second main cutting edges 42. The cutting edge width and sharpness of the second auxiliary cutting edges 43 are exactly the same as those of the first auxiliary cutting edges 33. They are used to finely finish the surface after the second main cutting edge 42 is cut, further reducing the surface roughness and improving the surface quality of the half-hole and the groove. Multiple second guide grooves 44 are respectively arranged between the multiple second main cutting edges 42 and the multiple second auxiliary cutting edges 43 to guide the chips generated by the cutting of the second cutter assembly 4, so as to realize the rapid discharge of chips.

[0028] In some embodiments, multiple second main cutting edges 42 are respectively connected to the bottom of multiple first main cutting edges 32, with a smooth transition at the connection point to ensure a continuous cutting trajectory and avoid cutting overlap or omission; multiple second auxiliary cutting edges 43 are respectively connected to the bottom of multiple first auxiliary cutting edges 33 to simultaneously realize the connection of finishing operations and improve the finishing effect; multiple second guide grooves 44 are respectively connected to multiple first guide grooves 34 to form a complete chip discharge channel, ensuring that the chips generated by the first cutting edge assembly 3 and the second cutting edge assembly 4 can slide smoothly and avoid chip accumulation in the guide groove.

[0029] In some embodiments, the helical direction of the second main cutting edge 42 is opposite to that of the first main cutting edge 32, and the helical direction of the second secondary cutting edge 43 is opposite to that of the first secondary cutting edge 33. This reverse helical design allows the chips generated by the cutting of the first cutting tool assembly 3 and the second cutting tool assembly 4 to converge towards the cleaning structure 2, achieving bidirectional chip collection, or to move away from the cleaning structure 2, achieving bidirectional chip removal, thereby improving chip removal efficiency. At the same time, the reverse helix can offset part of the cutting force, making the cutting force distribution more uniform, reducing tool vibration, and improving machining accuracy.

[0030] In some embodiments, the cutting angles of the first blade assembly 3 and the second blade assembly 4 are both 30°-45°. This cutting angle can be flexibly adjusted according to the characteristics of the processed material to adapt to PCB substrates and copper layers with different hardness. This can reduce cutting resistance, avoid blade wear, ensure smooth cutting, reduce burr generation, and balance cutting efficiency and processing quality.

[0031] In some embodiments, the angle between the axes of the first main cutting edge 32, the first secondary cutting edge 33 and the first cutting body 31 is 5°-10°, and the angle between the axes of the second main cutting edge 42, the second secondary cutting edge 43 and the second cutting body 41 is 5°-10°. This angle setting can enable the cutting edge to form a reasonable cutting rake angle, reduce cutting resistance, and at the same time ensure that the contact area between the cutting edge and the machined surface is moderate, avoiding excessive contact area leading to increased frictional resistance, or excessive contact area leading to stress concentration and chipping of the cutting edge.

[0032] In some embodiments, the helix angle of the first main cutting edge 32, the first secondary cutting edge 33, the second main cutting edge 42, and the second secondary cutting edge 43 is 25°~35°. This helix angle setting can make the cutting trajectory of the cutting edge smoother, further improve the uniformity of cutting force and chip removal efficiency. In addition, the surfaces of the first main cutting edge 32, the first secondary cutting edge 33, the second main cutting edge 42, and the second secondary cutting edge 43 are coated with a titanium nitride coating. This coating has high hardness, wear resistance and friction reduction properties, which can effectively reduce the coefficient of friction between the cutting edge and the workpiece material, reduce tool sticking, extend tool life, and improve the smoothness of the workpiece surface.

[0033] In some embodiments, the cleaning structure 2 includes a cleaning blind hole 21 and multiple cleaning ports 22, which work together to achieve efficient chip removal. The cleaning blind hole 21 coaxially penetrates the tool holder 1 and the first tool body 31, and extends to the top of the second tool body 41, forming a sealed chip collection space that can temporarily store the introduced chips for subsequent centralized discharge. The top of the cleaning blind hole 21 is connected to an external high-pressure air source or coolant supply device. Multiple cleaning ports 22 are arranged in a ring at the bottom of the cleaning blind hole 21 and are respectively connected to the connection points of multiple first guide grooves 34 and multiple second guide grooves 44. The high-pressure gas or coolant in the cleaning blind hole 21 can be transported to the cutting area to blow away the chips at the connection points of the first guide grooves 34 and the second guide grooves 44, preventing the chips from getting stuck and accumulating at the connection points, and ensuring the smooth discharge of the chips.

[0034] refer to Figure 4-6 A process for machining metallized half-holes on circuit boards, employing the aforementioned machining tools, achieves high-precision and high-efficiency machining of metallized half-holes through the coordinated operation of multiple processes. Specifically, it includes the following steps: Step S1: Drill through holes on the PCB board for forming metallized semi-holes. The diameter of the through holes is controlled to be 0.8mm-1.0mm. Before drilling, the PCB board needs to be cleaned to remove surface oil, dust, and oxide layers. A high-precision drilling machine is used during drilling, with the rotation speed controlled at 30,000-40,000 r / min and the feed rate at 0.1-0.2 mm / r. High-pressure air cooling is used to prevent the substrate from softening and carbonizing. After drilling, the through holes are deburred to ensure that the hole walls are flat, laying the foundation for the subsequent metallization process.

[0035] Step S2: A copper layer is deposited on the surface of the via wall using a combination of chemical copper plating and electroplating to form a stable conductive circuit. First, a thin copper layer of 0.5-1.0 μm thickness is deposited on the via wall surface using chemical copper plating as a conductive substrate, ensuring a tight bond between the subsequent electroplated copper layer and the via wall substrate. Then, the copper layer thickness is increased to 15-20 μm using electroplating to form a stable conductive circuit, meeting the conductivity and mechanical strength requirements of the metallized semi-hole. After electroplating, passivation, cleaning, and drying are performed to prevent copper oxidation.

[0036] Step S3: Fabricate outer layer circuits and outer layer circuit hole rings on the surface of the PCB board to achieve conductive connection between the metallized half-holes and the outer layer circuits of the PCB board. The outer layer circuitry and via rings are fabricated using photolithography. The outer layer circuit via rings are designed in an arc shape and are distributed around the through-holes outside the routing groove area. The center of the arc-shaped via ring coincides with the center of the through-hole, which ensures reliable conductive connection with the half-holes and reduces the space occupied on the PCB board, improving the board integration. After fabrication, the distance between the end of the outer layer circuit via ring and the edge of the routing groove area is precisely controlled by a copper stripping process, keeping it between 0.05mm and 0.1mm. This avoids damage to the via ring during routing and also prevents excessive spacing from wasting board space. After copper stripping, the ends of the via ring are polished to remove burrs and copper spikes, avoiding potential short circuit hazards.

[0037] Step S4: Use a coarse router cutter to create a router groove in the router groove forming area of ​​the PCB board along the pre-routing line. The router groove passes through the hole to initially form a metallized half-hole. The single-sided distance between the pre-routing line and the router groove forming line is controlled at 0.2mm~0.3mm to leave an appropriate amount of finishing allowance to facilitate the improvement of processing accuracy in subsequent finishing processes. The travel speed of the coarse router cutter is controlled at 0.4m / min~0.8m / min to balance coarse router efficiency and router groove surface flatness, and to avoid excessive burrs on the router groove edge due to excessive speed. High-pressure air cooling is used to assist in chip removal.

[0038] After rough milling is completed, the milling groove area is cleaned by using high-pressure air blowing to remove the chips from the milling groove. At the same time, the size and shape of the milling groove are checked. If there are any problems such as dimensional deviation or excessive burrs, rework is carried out in time to ensure that the quality of rough milling meets the requirements of fine finishing.

[0039] Step S5: Use the above-mentioned metallized half-hole machining tool for the circuit board to perform fine finishing work to ensure the dimensional accuracy and surface quality of the metallized half-hole and the slot; First, the metallization half-hole machining tool of the present invention is installed on the spindle of the machining equipment. The cutting angle of the tool is adjusted to 30°-45° to adapt to the machining characteristics of the PCB board. The cleaning structure 2 is activated, and high-pressure gas is introduced through the cleaning blind hole 21. The machining equipment is controlled to drive the tool to perform fine finishing along the forming line of the groove. During the fine finishing process, the tool holder 1 moves in a wave-shaped curve. That is, while the tool rotates and cuts, it makes a small reciprocating motion along the axial direction. In conjunction with the cleaning structure 2, the chips are continuously removed, which effectively avoids the copper foil on the hole wall from lifting and the burrs from remaining. At the same time, it reduces the wear of the cutting edge and extends the service life of the tool.

[0040] Step S6: Conduct a comprehensive inspection of the finished PCB board, focusing on the dimensional accuracy and wall quality of the metallized half-holes, the flatness of the copper foil, and the presence of any remaining burrs. Confirm that the half-hole dimensions, wall flatness, and copper adhesion meet the design requirements, and that there are no defects such as copper foil lifting, burrs, or micro-cracks. If the inspection is passed, complete all processing steps for the metallized half-holes. If the inspection fails, rework is required based on the type of defect. After rework, the inspection is repeated until the product quality meets the standards, ensuring that the product quality meets the standards.

[0041] In some embodiments, step S5 includes the following steps to further improve finishing accuracy and processing consistency, conforming to the actual processing operation flow: Step S51: Adjust the processing equipment and cutting tools. Align the connection between the first cutting tool assembly 3 and the second cutting tool assembly 4 with the bottom of one end of the hole wall to be finished. Calibrate the coaxiality of the cutting tool and the area to be finished to ensure accurate cutting trajectory. At the same time, start the cleaning structure 2 and introduce high-pressure gas to prepare for cutting.

[0042] Step S52: Start the processing equipment and drive the cutting tool to rotate at high speed, with the speed controllable at 35000-45000 r / min, so that the cutting tool can perform preliminary finishing on the hole wall to be finished. During the finishing process, slowly raise the cutting tool, controlling the raising speed at 0.5-1.0 mm / s, until the connection between the first cutting tool assembly 3 and the second cutting tool assembly 4 is flush with the top of the hole wall to be finished, completing the preliminary finishing of the hole wall at that end. The chips generated by cutting can be discharged in time under the guidance of the first guide groove 34 and the second guide groove 44 and the blowing of high-pressure gas or liquid. Since the spiral directions of the first cutting tool assembly 3 and the second cutting tool assembly 4 are opposite, the direction of the force between the first cutting tool assembly 3 and the second cutting tool assembly 4 and the hole wall to be finished is different when rotating synchronously. Through the action of the two forces in different directions, it can be ensured that the copper wire and glass fiber have sufficient force points at the hole wall, thereby avoiding wire pulling caused by avoidance. At the same time, chip removal channels in both the upper and lower directions can be formed between the tool and the hole wall to divert chips, improve chip removal speed, and avoid adverse effects such as chip accumulation causing scratches on the hole wall.

[0043] Step S53: Keep the tool rotating and slowly move the tool to the other end of the hole wall to be fine-tuned. During the movement, control the tool holder 1 to move up and down in sync. Coordinate with the movement of the tool holder 1 to form a wave-like movement. The single movement height of the tool holder 1 is controlled at 0.1-0.2mm, and the overall movement height is less than the height of the hole wall to be fine-tuned. This ensures that during the fine-tuning process, the hole wall to be fine-tuned is always in contact with the first tool assembly 3 and the second tool assembly 4 at the same time, ensuring bidirectional fine-tuning of the hole wall to be fine-tuned, further improving the cleaning effect and finishing quality, and avoiding cutting dead angles.

[0044] Step S54: When the tool moves to the other end of the hole wall to be finished, and the connection between the first tool assembly 3 and the second tool assembly 4 is flush with the bottom or top of that end, stop moving the tool; control the tool to slowly move up or down to repair the hole wall and the edge of the groove at that end, thoroughly remove residual material and burrs, and complete all finishing work on the hole wall to be finished; after finishing, close the cleaning structure 2, move the tool to the next cutting point, and repeat the above steps S51-S54 until all metallized half holes are finished.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tool for machining metallized half-holes in circuit boards, including a tool holder (1); The blade structure is coaxially disposed at the bottom of the blade holder (1); Its features are: It also includes a cleaning structure (2), which is located between the tool holder (1) and the cutting edge structure, and can realize the timely removal of chips during the cutting process; The blade structure includes a first blade assembly (3), which is coaxially disposed at the bottom of the blade holder (1); The second blade assembly (4) is coaxially disposed at the bottom of the first blade assembly (3), and the spiral direction of the first blade assembly (3) is opposite to the spiral direction of the second blade assembly (4). The cleaning structure (2) is provided at the connection between the first blade assembly (3) and the second blade assembly (4).

2. The cutting tool for machining metallized half-holes in circuit boards according to claim 1, characterized in that: The first blade assembly (3) includes a first blade body (31), which is coaxially disposed at the bottom of the blade holder (1); Multiple first main cutting edges (32) are spirally arranged around the first blade body (31); Multiple first secondary blades (33) are spirally arranged around the first blade body (31); and the first secondary blades (33) are located between two adjacent first main blades (32); Multiple first guide grooves (34) are respectively disposed between multiple first main blades (32) and multiple first secondary blades (33).

3. The cutting tool for machining metallized half-holes in circuit boards according to claim 2, characterized in that: The second blade assembly (4) includes a second blade body (41), which is coaxially disposed at the bottom of the first blade body (31); Multiple second main cutting edges (42) are spirally arranged around the second blade body (41); Multiple secondary blades (43) are spirally arranged around the second blade body (41); and the secondary blades (43) are located between two adjacent secondary blades (42); Multiple second guide grooves (44) are provided between multiple second main cutting edges (42) and multiple second secondary cutting edges (43).

4. The cutting tool for machining metallized half-holes in circuit boards according to claim 3, characterized in that: Multiple second main blades (42) are connected to the bottom of multiple first main blades (32), multiple second auxiliary blades (43) are connected to the bottom of multiple first auxiliary blades (33), and multiple second guide grooves (44) are connected to multiple first guide grooves (34).

5. The cutting tool for machining metallized half-holes in circuit boards according to claim 4, characterized in that: The spiral direction of the second main blade (42) is opposite to that of the first main blade (32), and the spiral direction of the second secondary blade (43) is opposite to that of the first secondary blade (33).

6. The circuit board metallization half-hole machining tool according to claim 3, characterized in that: The angle between the first main blade (32), the first secondary blade (33) and the axis of the first blade body (31) is 5°-10°, and the angle between the second main blade (42), the second secondary blade (43) and the axis of the second blade body (41) is 5°-10°.

7. The cutting tool for machining metallized half-holes in circuit boards according to claim 3, characterized in that: The first main blade (32), the first secondary blade (33), the second main blade (42), and the second secondary blade (43) have a helix angle of 25°~35°, and the surfaces of the first main blade (32), the first secondary blade (33), the second main blade (42), and the second secondary blade (43) are coated with a titanium nitride coating.

8. The cutting tool for machining metallized half-holes in circuit boards according to claim 3, characterized in that: The cleaning structure (2) includes a cleaning blind hole (21), which coaxially passes through the tool holder (1) and the first tool body (31) and extends to the top of the second tool body (41); Multiple cleaning ports (22) are arranged in a ring at the bottom of the cleaning blind hole (21) and are respectively connected to the connection points of multiple first guide grooves (34) and multiple second guide grooves (44).

9. A process for machining metallized half-holes in circuit boards, using the metallized half-hole machining tool as described in any one of claims 1-8, characterized in that: Includes the following steps: Step S1: Drill through holes on the PCB board for forming metallized half-holes, wherein the diameter of the through holes is 0.8mm-1.0mm; Step S2: A copper layer is deposited on the surface of the hole wall of the through hole using a combination of chemical copper plating and electroplating thickening process to form a conductive circuit; Step S3: Fabricate outer layer circuitry and outer layer circuitry via rings on the surface of the PCB board; Step S4: Use a coarse router cutter to create a router groove in the router groove forming area of ​​the PCB board along the pre-router line. The router groove penetrates the through hole to initially form a metallized half hole. Step S5: Adjust the cutting angle of the tool to 30°-45° and perform fine finishing along the forming line of the groove. During the fine finishing process, the tool holder (1) moves in a wave-shaped curve, and the cleaning structure (2) continuously removes chips to avoid the copper foil on the hole wall from lifting and the burrs from remaining. Step S6: Inspect the size and wall quality of the metallized half-holes on the finished PCB board. Once the inspection is passed, the metallized half-holes are processed.

10. The circuit board metallization half-hole processing technology according to claim 9, characterized in that: Step S5 includes the following steps: Step S51: Align the connection point between the first blade assembly (3) and the second blade assembly (4) with the bottom of one end of the hole wall to be finished; Step S52: Rotate the cutting tool to refine the wall of the hole to be refined, and lift the cutting tool so that the connection between the first cutting tool assembly (3) and the second cutting tool assembly (4) is flush with the top of the end of the wall of the hole to be refined. Step S53: Move the cutting tool to the other end of the hole wall to be repaired. During the movement, make the tool holder (1) move up and down simultaneously until the connection between the first tool assembly (3) and the second tool assembly (4) is flush with the bottom or top of the other end of the hole wall to be repaired. The moving height of the tool holder (1) is less than the height of the hole wall to be repaired. Step S54: Stop moving the cutting tool, and move the cutting tool up or down to complete the finishing of the hole wall to be finished.

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