A method of drilling a PCB board

Abstract

The application discloses a PCB drilling method and relates to the technical field of circuit board processing.The method comprises the following steps: S10, providing a metal sheet and drilling a plurality of guide holes in the sheet by using a micro drill; S20, filling and solidifying graphite resin in the lower half of the guide holes to form a lubricating layer in the lower half of the guide holes; S30, filling ordinary resin in the upper half of the guide holes and semi-solidifying the ordinary resin to form a positioning layer in the upper half of the guide holes; S40, covering the metal sheet on a PCB to be processed and aligning the guide holes with target hole positions on the PCB; S50, using the micro drill to sequentially pass through the positioning layer, the lubricating layer and the PCB above the guide holes to once drill the target hole; and S60, removing the metal sheet after the target hole is drilled to obtain a processed PCB.The application has the beneficial effects of realizing small drilling effects with low broken needle rate, high hole wall quality and no influence on signal transmission.

Description

Technical Field

[0001] This invention relates to the field of circuit board processing technology, and more specifically, to a drilling method for PCB boards. Background Technology

[0002] With the miniaturization of electronic components and the development of high-density interconnect technologies, the manufacturing process of printed circuit boards (PCBs) faces increasingly stringent precision requirements. This is particularly true in the field of high-multilayer thick boards, where the finished board thickness typically exceeds 3.2 mm, while the minimum drill hole diameter has shrunk to below 0.15 mm. Under these extreme dimensional conditions, the rigidity of the drill bit is approaching its physical limit, leading to numerous defects in existing drilling methods.

[0003] In existing technologies, commonly used drilling methods mainly include the following: Firstly, there's the single-drill-through method. This involves using a micro drill bit to drill directly from the surface of the board down through the entire thickness in one go. However, due to the extremely small diameter of the drill bit (≤0.15mm) and insufficient rigidity, when penetrating boards thicker than 3.2mm, the drill bit experiences extremely high torque and lateral forces, resulting in a very high probability of needle breakage, which severely impacts production efficiency and processing costs.

[0004] Secondly, there is the segmented drilling method. To avoid needle breakage, some processes involve drilling a portion of the hole first, then flipping the plate over and continuing drilling from the other side until the hole is fully drilled. However, this method causes the drill bit to rub against the hole wall multiple times when withdrawing and re-entering the hole, resulting in increased hole wall roughness, burrs, and even delamination. The hole wall quality is very poor and cannot meet the requirements of subsequent electroplating and signal transmission.

[0005] Thirdly, there is the reverse drilling method. This involves drilling holes from both sides of the board, with the two holes meeting at the midpoint of the board thickness. While this method reduces the depth of a single drilling operation, it can easily lead to misalignment or steps at the connection point, causing discontinuities in the signal transmission path. In high-frequency and high-speed applications, this can result in severe impedance changes and signal loss, affecting the electrical performance of the product.

[0006] In addition, the industry has tried to use coated aluminum sheets as top cover plates or coated drill bits to reduce friction and improve chip removal. However, when faced with the extreme combination of "plate thickness ≥ 3.2 mm and hole diameter ≤ 0.15 mm", the above-mentioned auxiliary methods are still difficult to fundamentally solve the problems of drill bit breakage and hole wall quality deterioration.

[0007] Therefore, this invention provides a drilling method for PCB boards, which can solve the problems of high needle breakage rate, poor hole wall quality, and signal transmission impact in existing micro-drilling technology for multilayer thick boards, thereby achieving a micro-drilling effect with low needle breakage rate, high hole wall quality, and no impact on signal transmission. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, this invention provides a drilling method for PCB boards, which can solve the problems of high needle breakage rate, poor hole wall quality, and signal transmission impact in existing micro-drilling technology for multilayer thick boards. This achieves a micro-drilling effect with low needle breakage rate, high hole wall quality, and no impact on signal transmission.

[0009] The technical solution adopted by this invention to solve its technical problem is: a drilling method for a PCB board, wherein the improvement is that the drilling method for the PCB board includes the following steps: S10 provides a metal sheet and drills multiple guide holes in the sheet using a micro drill; S20, fill and cure graphite resin in the lower half of the guide hole to form a lubricating layer in the lower half of the guide hole; S30, fill the upper half of the guide hole with ordinary resin and semi-cur the ordinary resin to form a positioning layer in the upper half of the guide hole. S40: Cover the PCB board to be processed with a thin metal sheet and align the guide holes with the target holes on the PCB board; The S50 uses a miniature drill to drill through the positioning layer, lubrication layer, and PCB board of the guide hole in sequence, passing above the guide hole, and drills through the target hole in one go. S60: After the target hole is drilled, the metal sheet is removed to obtain the processed PCB board.

[0010] Furthermore, in step S10, the metal sheet is made of 304 stainless steel with a thickness between 0.1mm and 0.2mm, and its length and width dimensions are adapted to the length and width dimensions of the PCB board.

[0011] Furthermore, the guide hole is drilled using a drill bit with a cutting length between 0.16mm and 0.2mm and a diameter between 0.18mm and 0.22mm.

[0012] Furthermore, in step S20, the graphite resin is an epoxy resin with a graphite sphere content of 5%.

[0013] Furthermore, the graphite resin is cured in stages at 80℃, 100℃, 110℃, and 150℃.

[0014] Furthermore, in step S30, the semi-curing method of the ordinary resin is as follows: semi-curing is carried out in stages at 80°C and 100°C in sequence.

[0015] Furthermore, in step S40, the size of the guide hole is 0.05 mm larger than that of the target hole.

[0016] Furthermore, in step 50, the target hole is drilled using a drill bit with a cutting length greater than the PCB board thickness by 0.7 mm and a diameter between 0.1 mm and 0.2 mm.

[0017] The beneficial effects of this invention are as follows: By pre-drilling guide holes in a metal sheet and filling the guide holes with graphite resin and ordinary resin in two parts (upper and lower), a lubrication layer and a positioning layer are formed in the guide holes. Then, the sheet is covered on the PCB board for one-time drilling. The positioning layer provides precise guidance and support for the drill bit, significantly reducing lateral force and the risk of deviation, thereby greatly reducing the needle breakage rate. The lubrication layer continuously releases graphite during the drilling process, effectively reducing friction between the drill bit and the hole wall, reducing torque, and improving chip removal. This avoids rough hole walls, burrs, or delamination caused by repeated friction, ensuring excellent hole wall quality. At the same time, because a one-time drilling method is used instead of segmented or butt joints, steps or misalignments within the hole are avoided, ensuring a continuous signal transmission path and eliminating impedance changes and signal loss in high-frequency applications. Therefore, this invention can solve the problems of high needle breakage rate, poor hole wall quality, and signal transmission impact in existing micro-drilling technology for multilayer thick boards, thus achieving a micro-drilling effect with low needle breakage rate, high hole wall quality, and no impact on signal transmission. Attached Figure Description

[0018] Figure 1 This is an overall flowchart of a PCB board drilling method according to the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0021] Example 1: Reference Figure 1 As shown, this invention discloses a drilling method for a PCB board, which includes the following steps: S10, a metal sheet is provided, and multiple guide holes are drilled on the sheet using a micro drill; preferably, the metal sheet is made of 304 stainless steel with a thickness of 0.1mm, and its length and width dimensions are adapted to the length and width dimensions of the PCB board to be processed, so as to ensure that the subsequent metal sheet and PCB board are completely covered, and the guide holes are drilled using a drill bit with a cutting edge of 0.16mm and a diameter of 0.18mm; S20, graphite resin is filled and cured in the lower half of the guide hole to form a lubricating layer in the lower half of the guide hole; specifically, the graphite resin is epoxy resin with a graphite ball content of 5%, that is, the mass fraction of graphite balls is about 5%. The guide hole is filled on one side of the stainless steel sheet with the guide hole by a horizontal plugging machine to complete the filling of the lower half of the guide hole. After filling, the graphite resin is cured. The preferred curing method is staged heating: the resin is held at 80℃, 100℃, 110℃ and 150℃ for a certain time (e.g., 80℃ for 30min, 100℃ for 30min, 110℃ for 30min and 150℃ for 60min) in stages to ensure that the resin is fully cured and the internal stress is released uniformly. S30, ordinary resin is filled into the upper half of the guide hole, and the ordinary resin is semi-cured to form a positioning layer in the upper half of the guide hole; wherein, the ordinary resin can be conventional epoxy resin, which is used to fill the guide hole with resin by a vertical vacuum plugging machine to complete the filling of the upper half of the guide hole; and the semi-curing method of the ordinary resin is preferably: semi-curing in stages by holding it at 80℃ and 100℃ for a certain time (e.g., 30 min at 80℃ and 10 min at 100℃), so that the resin has a certain hardness to support the drill tip, and retains a certain viscoelasticity to achieve precise centering. S40: A thin metal sheet is placed over the PCB board to be processed, and the guide hole is aligned with the target hole on the PCB board. To ensure alignment accuracy, the size of the guide hole is 0.05mm larger than the target hole, that is, the diameter of the guide hole is approximately equal to the diameter of the target hole plus 0.05mm. This provides an appropriate clearance for the drill bit to limit its oscillation, while not being too loose to cause positioning failure. S50: Using a miniature drill, the drill passes sequentially through the positioning layer, lubrication layer, and PCB board above the guide hole, drilling through the target hole in one pass. Preferably, the target hole is drilled using a drill bit with a cutting edge length greater than the PCB board thickness by 0.7 mm and a diameter of 0.1 mm. Because the cutting edge is long enough, it can penetrate the total thickness of the metal sheet and the PCB board in one pass, avoiding segmented drilling. During drilling, the drill tip first contacts the semi-cured positioning layer, where it is viscoelastically fixed to prevent slippage. Then, the drill bit enters the lubrication layer containing graphite balls; the graphite components adhere to the drill bit's chip grooves, providing continuous lubrication and reducing friction and heat. Finally, under the rigid constraint of the guide hole, the drill bit vertically passes through the PCB board, ensuring hole position accuracy and hole wall quality.

[0022] S60: After the target holes are drilled, the metal sheet is removed to obtain the processed PCB board. At this point, the hole positions on the PCB board are accurate and the hole walls are smooth, allowing it to proceed directly to subsequent routine processes (such as deburring, electroplating, etc.).

[0023] Example 2: Reference Figure 1 As shown, this invention discloses a drilling method for a PCB board, which includes the following steps: S10, a metal sheet is provided, and multiple guide holes are drilled on the sheet using a micro drill; preferably, the metal sheet is made of 304 stainless steel with a thickness of 0.15mm, and its length and width dimensions are adapted to the length and width dimensions of the PCB board to be processed, so as to ensure that the subsequent metal sheet and PCB board are completely covered, and the guide holes are drilled using a drill bit with a cutting edge of 0.18mm and a diameter of 0.2mm; S20, graphite resin is filled and cured in the lower half of the guide hole to form a lubricating layer in the lower half of the guide hole; specifically, the graphite resin is epoxy resin with a graphite ball content of 5%, that is, the mass fraction of graphite balls is about 5%. The guide hole is filled on one side of the stainless steel sheet with the guide hole by a horizontal plugging machine to complete the filling of the lower half of the guide hole. After filling, the graphite resin is cured. The preferred curing method is staged heating: the resin is held at 80℃, 100℃, 110℃ and 150℃ for a certain time (e.g., 80℃ for 30min, 100℃ for 30min, 110℃ for 30min and 150℃ for 60min) in stages to ensure that the resin is fully cured and the internal stress is released uniformly. S30, ordinary resin is filled into the upper half of the guide hole, and the ordinary resin is semi-cured to form a positioning layer in the upper half of the guide hole; wherein, the ordinary resin can be conventional epoxy resin, which is used to fill the guide hole with resin by a vertical vacuum plugging machine to complete the filling of the upper half of the guide hole; and the semi-curing method of the ordinary resin is preferably: semi-curing in stages by holding it at 80℃ and 100℃ for a certain time (e.g., 30 min at 80℃ and 10 min at 100℃), so that the resin has a certain hardness to support the drill tip, and retains a certain viscoelasticity to achieve precise centering. S40: A thin metal sheet is placed over the PCB board to be processed, and the guide hole is aligned with the target hole on the PCB board. To ensure alignment accuracy, the size of the guide hole is 0.05mm larger than the target hole, that is, the diameter of the guide hole is approximately equal to the diameter of the target hole plus 0.05mm. This provides an appropriate clearance for the drill bit to limit its oscillation, while not being too loose to cause positioning failure. S50, using a miniature drill bit, the drill passes sequentially through the positioning layer, lubrication layer, and PCB board above the guide hole, drilling through the target hole in one pass. Preferably, the target hole is drilled using a drill bit with a cutting edge length greater than the PCB board thickness by 0.7 mm and a diameter of 0.15 mm. Because the cutting edge length is sufficiently long, it can penetrate the total thickness of the metal sheet and the PCB board in one pass, avoiding segmented drilling. During drilling, the drill tip first contacts the semi-cured positioning layer, where it is viscoelastically fixed to prevent slippage. Then, the drill bit enters the lubrication layer containing graphite balls; the graphite components adhere to the drill bit's chip grooves, providing continuous lubrication and reducing friction and heat. Finally, under the rigid constraint of the guide hole, the drill bit vertically passes through the PCB board, ensuring hole position accuracy and hole wall quality.

[0024] S60: After the target holes are drilled, the metal sheet is removed to obtain the processed PCB board. At this point, the hole positions on the PCB board are accurate and the hole walls are smooth, allowing it to proceed directly to subsequent routine processes (such as deburring, electroplating, etc.).

[0025] Example 3: Reference Figure 1 As shown, this invention discloses a drilling method for a PCB board, which includes the following steps: S10, a metal sheet is provided, and multiple guide holes are drilled on the sheet using a micro drill; preferably, the metal sheet is made of 304 stainless steel with a thickness of 0.2mm, and its length and width dimensions are adapted to the length and width dimensions of the PCB board to be processed, so as to ensure that the subsequent metal sheet and PCB board are completely covered, and the guide holes are drilled using a drill bit with a cutting edge of 0.2mm in length and 0.22mm in diameter; S20, graphite resin is filled and cured in the lower half of the guide hole to form a lubricating layer in the lower half of the guide hole; specifically, the graphite resin is epoxy resin with a graphite ball content of 5%, that is, the mass fraction of graphite balls is about 5%. The guide hole is filled on one side of the stainless steel sheet with the guide hole by a horizontal plugging machine to complete the filling of the lower half of the guide hole. After filling, the graphite resin is cured. The preferred curing method is staged heating: the resin is held at 80℃, 100℃, 110℃ and 150℃ for a certain time (e.g., 80℃ for 30min, 100℃ for 30min, 110℃ for 30min and 150℃ for 60min) in stages to ensure that the resin is fully cured and the internal stress is released uniformly. S30, ordinary resin is filled into the upper half of the guide hole, and the ordinary resin is semi-cured to form a positioning layer in the upper half of the guide hole; wherein, the ordinary resin can be conventional epoxy resin, which is used to fill the guide hole with resin by a vertical vacuum plugging machine to complete the filling of the upper half of the guide hole; and the semi-curing method of the ordinary resin is preferably: semi-curing in stages by holding it at 80℃ and 100℃ for a certain time (e.g., 30 min at 80℃ and 10 min at 100℃), so that the resin has a certain hardness to support the drill tip, and retains a certain viscoelasticity to achieve precise centering. S40: A thin metal sheet is placed over the PCB board to be processed, and the guide hole is aligned with the target hole on the PCB board. To ensure alignment accuracy, the size of the guide hole is 0.05mm larger than the target hole, that is, the diameter of the guide hole is approximately equal to the diameter of the target hole plus 0.05mm. This provides an appropriate clearance for the drill bit to limit its oscillation, while not being too loose to cause positioning failure. S50: Using a miniature drill, the drill passes sequentially through the positioning layer, lubrication layer, and PCB board above the guide hole, drilling through the target hole in one pass. Preferably, the target hole is drilled using a drill bit with a cutting edge length greater than the PCB board thickness by 0.7 mm and a diameter of 0.2 mm. Because the cutting edge is long enough, it can penetrate the total thickness of the metal sheet and the PCB board in one pass, avoiding segmented drilling. During drilling, the drill tip first contacts the semi-cured positioning layer, where it is viscoelastically fixed to prevent slippage. Then, the drill bit enters the lubrication layer containing graphite balls; the graphite components adhere to the drill bit's chip grooves, providing continuous lubrication and reducing friction and heat. Finally, under the rigid constraint of the guide hole, the drill bit vertically passes through the PCB board, ensuring hole position accuracy and hole wall quality.

[0026] S60: After the target holes are drilled, the metal sheet is removed to obtain the processed PCB board. At this point, the hole positions on the PCB board are accurate and the hole walls are smooth, allowing it to proceed directly to subsequent routine processes (such as deburring, electroplating, etc.).

[0027] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention pre-drills guide holes in a metal sheet and fills the guide holes with graphite resin and ordinary resin in two parts to form a lubrication layer and a positioning layer in the guide holes. Then, the sheet is covered on the PCB board for one-time drilling. The positioning layer provides precise guidance and support for the drill bit, significantly reducing lateral force and the risk of deviation, thereby greatly reducing the needle breakage rate. The lubrication layer continuously releases graphite during the drilling process, effectively reducing friction between the drill bit and the hole wall, reducing torque, and improving chip removal. This avoids rough hole walls, burrs, or delamination caused by repeated friction, ensuring excellent hole wall quality. At the same time, since a one-time drilling method is used instead of segmented or butt joints, steps or misalignments within the hole are avoided, ensuring a continuous signal transmission path and eliminating impedance changes and signal loss in high-frequency applications. Therefore, this invention can solve the problems of high needle breakage rate, poor hole wall quality, and signal transmission impact in existing micro-drilling technologies for multilayer thick boards, thus achieving a micro-drilling effect with low needle breakage rate, high hole wall quality, and no impact on signal transmission.

[0028] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A drilling method for a PCB board, characterized in that, The drilling method for the PCB board includes the following steps: S10 provides a metal sheet and drills multiple guide holes in the sheet using a micro drill; S20, fill and cure graphite resin in the lower half of the guide hole to form a lubricating layer in the lower half of the guide hole; S30, fill the upper half of the guide hole with ordinary resin and semi-cur the ordinary resin to form a positioning layer in the upper half of the guide hole. S40: Cover the PCB board to be processed with a metal sheet and align the guide hole with the target hole on the PCB board; The S50 uses a miniature drill to drill through the positioning layer, lubrication layer, and PCB board of the guide hole in sequence, passing above the guide hole, and drills through the target hole in one go. S60: After the target hole is drilled, the metal sheet is removed to obtain the processed PCB board.

2. The drilling method for a PCB board according to claim 1, characterized in that, In step S10, the metal sheet is made of 304 stainless steel with a thickness between 0.1mm and 0.2mm, and its length and width dimensions are adapted to the length and width dimensions of the PCB board.

3. The drilling method for a PCB board according to claim 1, characterized in that, The guide hole is drilled using a drill bit with a cutting length between 0.16mm and 0.2mm and a diameter between 0.18mm and 0.22mm.

4. The drilling method for a PCB board according to claim 1, characterized in that, In step S20, the graphite resin is an epoxy resin with 5% graphite spheres.

5. A drilling method for a PCB board according to claim 4, characterized in that, The graphite resin is cured in stages at 80℃, 100℃, 110℃, and 150℃.

6. The drilling method for a PCB board according to claim 1, characterized in that, In step S30, the semi-curing method of the ordinary resin is as follows: semi-curing is carried out in stages at 80°C and 100°C.

7. The drilling method for a PCB board according to claim 1, characterized in that, In step S40, the size of the guide hole is 0.05 mm larger than that of the target hole.

8. A drilling method for a PCB board according to claim 1, characterized in that, In step 50, the target hole is drilled using a drill bit with a cutting length greater than the PCB board thickness by 0.7 mm and a diameter between 0.1 mm and 0.2 mm.

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