A method and plugging tool for preventing base copper grinding damage to vias

Abstract

This invention discloses a method and tool for preventing damage to the copper surface during platen via grinding, belonging to the field of printed circuit board technology. The method includes: providing a platen via-filling aluminum sheet, on which normal platen via patterns are provided, and in the area surrounding the corresponding platen via insertion holes, dummy-dot platen via patterns are provided; after aligning the platen via-filling aluminum sheet with the board to be plated, resin platen via filling is performed, so that resin ink simultaneously fills the board surface areas corresponding to the normal platen vias and the dummy-dot vias; after curing, resin support points are formed around the insertion holes; during grinding, these resin support points support the grinding brush, preventing the brush from extending to the edge of the insertion hole and damaging the copper surface of the hole. This invention also discloses a via-filling tool for the above method. By adding dummy-dot platen via patterns, this invention effectively solves the problem of easy damage to the copper surface around the insertion holes during grinding without changing the existing via-filling process, thus improving product yield and reliability.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board technology, and in particular to a method and tool for preventing the base copper from being ground and damaged during via filling. Background Technology

[0002] In the development of the printed circuit board industry, resin ink via filling technology is widely used in high-multilayer, HDI, high-frequency and high-speed circuit boards. The core of resin via filling technology is to solve five major problems: production, soldering, high density, electrical, and reliability. It is compatible with HDI, BGA, and high-frequency and high-speed boards.

[0003] The main functions of using resin ink for hole plugging are as follows: 1. Production process assurance (essential for multilayer boards) a. Preventing lamination bursting / insufficient adhesive: The inner layer blind buried holes are filled with resin to prevent the semi-cured sheet (PP) from flowing into the holes during lamination, thus preventing lamination voids, delamination, and bursting.

[0004] b. Increase lamination vacuum: Expel air from the holes to quickly establish lamination vacuum, resulting in tighter bonding between layers.

[0005] c. Flat board surface: Avoid hole recesses to ensure fine circuitry, impedance control, and subsequent electroplating / mounting accuracy.

[0006] 2. Soldering and SMT reliability (through-pad core) a. Preventing solder loss / cold solder joints: After the Via-in-pad is filled, the solder will not flow into the hole, ensuring the pad area and solder joint strength.

[0007] b. Prevent solder ball short circuit: During wave soldering, prevent solder balls from popping out of the holes and causing a short circuit.

[0008] c. No residual hazards: Avoid flux and moisture residue in the holes, which can cause corrosion, bubbles, and delamination.

[0009] 3. High density and space utilization (miniaturization is a necessity) a. Supports via-in-pad: For BGA / QFN and other close-pitch packages, pads can be directly placed on the vias, significantly increasing wiring density.

[0010] b. Hole stacking / arbitrary layer interconnection: Enables 3D routing, saves board space, and is compatible with HDI boards.

[0011] 4. Electrical performance optimization (high-frequency / high-speed boards) a. Improve signal integrity: Low-loss resin suppresses the hole-wall antenna effect, crosstalk and reflection, reducing signal attenuation.

[0012] b. Stable impedance: Flat surface + uniform dielectric to ensure consistent impedance of high-frequency signals.

[0013] c. Isolate interference: Isolate the copper inside the via from the outer layer circuitry to reduce capacitance / crosstalk.

[0014] 5. Long-term reliability (harsh environment) a. Anti-oxidation and corrosion: Seals the channels, isolates moisture, salt spray, and chemicals, and protects the copper layer on the hole walls.

[0015] b. Thermal stress resistance: The resin buffers thermal expansion and contraction, reducing the risk of copper cracking and delamination in the hole walls.

[0016] c. Extended lifespan: Suitable for high-reliability applications such as automotive, medical, and industrial applications.

[0017] However, in resin-filled via polishing processes, especially when the outermost layer after lamination has large insertion holes, the polishing brush of the resin has a certain degree of flexibility. The area around the insertion holes is too open, and during polishing, the brush will directly grind to the edge of the insertion hole, damaging the copper surface and causing exposed substrate defects (such as...). Figure 1 (As shown). Summary of the Invention

[0018] The purpose of this invention is to provide a method for preventing the base copper from being ground and damaged by the plugging hole.

[0019] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preventing base copper grinding damage to vias includes the following steps: A plugging aluminum sheet is provided, wherein a normal plugging pattern is provided on the plugging aluminum sheet, and a fake plugging pattern is provided in the area around the corresponding printed circuit board plug hole; Align the plugging aluminum sheet with the printed circuit board to which the hole is to be plugged; The resin is used to plug the holes with the aluminum sheet, so that the resin ink fills the printed circuit board holes corresponding to the normal plug pattern and the peripheral board surface of the printed circuit board plug hole corresponding to the fake plug pattern. The filled resin ink is cured to form resin support points around the plug hole; The grinding process is performed, and the resin support points support the grinding brush to prevent the grinding brush from extending to the edge of the plug hole and damaging the copper surface of the hole.

[0020] Preferably, the dummy plug hole pattern is evenly distributed around the corresponding position of the plug hole, with one dummy plug hole set at every 0.5mm interval.

[0021] Preferably, the distance between the dummy plug hole pattern and the edge of the plug hole is 1 mm.

[0022] Preferably, the distance between the dummy plug pattern and the normal plug pattern is 0.5 mm to 0.8 mm.

[0023] Preferably, when the area around the plug hole is open, the dummy plug hole pattern covers at least 3mm of the area around the plug hole ring.

[0024] Preferably, the aperture of the dummy plug pattern is designed according to the conventional plug aperture, which is 0.35 mm.

[0025] Preferably, the cured pseudo-pore-filling resin and the normal pore-filling resin are removed simultaneously during the grinding step.

[0026] A plugging tool, wherein the plugging tool is a plugging aluminum sheet, the plugging aluminum sheet is provided with a normal plugging pattern, and a fake plugging pattern is provided in the area around the corresponding printed circuit board plug hole.

[0027] Furthermore, the dummy plug patterns are evenly spaced around the corresponding positions of the plug hole, with one dummy plug at every 0.5 mm interval; the distance between the dummy plug pattern and the edge of the plug hole is 1 mm; and the distance between the dummy plug pattern and the normal plug pattern is 0.5 mm to 0.8 mm.

[0028] Furthermore, when the area around the plug hole is open, the dummy plug hole pattern covers at least 3 mm of the area around the plug hole ring; the diameter of the dummy plug hole pattern is 0.35 mm.

[0029] When plugging the insertion hole, the ink is applied to the surrounding surface of the PCB insertion hole at the same time as normal plugging. After the resin ink is cured at high temperature, it is removed by grinding at the same time as normal resin. Because the insertion hole is supported and protected by the pseudo-dot plugging resin, the grinding brush will grind the plugging resin and pseudo-dot resin at the same time, and will not grind directly to the edge of the insertion hole on the board surface, thus achieving the effect of not damaging the hole opening. Attached Figure Description

[0030] Figure 1 A schematic diagram of copper damage at the opening of the plug-in hole; Figure 2 This is a schematic diagram of the plugged aluminum sheet structure before the preferred embodiment of the present invention; Figure 3 This is a schematic diagram of the optimized plugged aluminum sheet structure of the present invention; Figure 4 This is the optimized plug production diagram of the present invention; Figure 5 This is a diagram showing the optimized hole-filling grinding effect of the present invention. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, but this does not constitute a limitation on the scope of protection of the present invention.

[0032] See Figure 2-5 As shown; Figure 2 A schematic diagram of the optimized front plug hole aluminum sheet structure; Figure 3 This is a schematic diagram of the modified aluminum sheet structure for plugging holes according to the present invention, in which the spatial arrangement relationship between the normal plugging hole pattern and the fake plugging hole pattern is clearly shown. This invention provides a method for preventing through-hole damage from copper grinding, comprising the following steps: A plugging aluminum sheet is provided, on which normal plugging patterns are provided, and in the area around the corresponding printed circuit board insertion holes, dummy plugging patterns are provided (e.g., Figure 2 (as shown) Align the aluminum sheet used for plugging holes with the printed circuit board containing the holes to be plugged; Resin is used to plug holes with aluminum sheets, so that the resin ink fills the printed circuit board holes corresponding to normal plug patterns and the board surface around the plug holes corresponding to false plug patterns. The filled resin ink is cured to form resin support points around the plug hole; The grinding process involves using resin support points to support the grinding brush, preventing the brush from extending to the edge of the insertion hole and damaging the copper surface of the hole.

[0033] In a preferred embodiment of the present invention, the dummy dot plugging hole pattern is evenly distributed around the position corresponding to the plug hole, with one dummy dot plugging hole set at every 0.5 mm interval; the distance between the dummy dot plugging hole pattern and the edge of the plug hole is 1 mm to prevent ink from entering the plug hole due to printing pressure when the hole is too close.

[0034] In another preferred embodiment of the present invention, the distance between the dummy plug pattern and the normal plug pattern is 0.5 mm to 0.8 mm. This setting is to prevent the holes from being too close together, which would cause the plugging resin to clump together, resulting in overlapping oil accumulation and making grinding difficult. When there are few resin plugs around the insertion hole and the hole opening edge is relatively open, the dummy plug pattern must cover at least 3 mm around the hole ring to provide sufficient support for grinding.

[0035] In another preferred embodiment of the present invention, the aperture of the dummy plug pattern is designed according to the conventional plug aperture, which is 0.35 mm.

[0036] The cured pseudo-pore-filling resin and normal pore-filling resin are removed simultaneously during the grinding step.

[0037] When plugging the insertion hole, ink is applied to the surrounding surface of the PCB insertion hole at the same time as normal insertion. After the resin ink is cured at high temperature, it is removed by grinding simultaneously with the normal resin. Because the insertion hole is supported and protected by the pseudo-dot insertion resin, the grinding brush will grind the insertion resin and pseudo-dot resin at the same time, without directly grinding the edge of the insertion hole on the board surface, thus achieving the effect of not damaging the hole opening.

[0038] This invention also provides a plugging tool, which is a plugging aluminum sheet. A normal plugging pattern is formed on the aluminum sheet, and dummy plugging patterns are formed in the area surrounding the corresponding printed circuit board insertion holes. The dummy plugging patterns are evenly distributed around the corresponding positions of the insertion holes, with one dummy plugging hole every 0.5 mm. The distance between the dummy plugging pattern and the edge of the insertion hole is 1 mm; the distance between the dummy plugging pattern and the normal plugging pattern is 0.5 mm to 0.8 mm. When the area around the insertion hole is open, the dummy plugging pattern covers at least 3 mm of the area around the insertion hole ring; the diameter of the dummy plugging pattern is 0.35 mm.

[0039]

[0040] In summary, compared with the prior art, the present invention has the following beneficial effects: 1. Effectively solves the problem of grinding damage to insertion holes, improving product yield. In existing resin plugging processes, the area around the insertion hole is open, and during grinding, the flexible brush can easily get stuck at the edge of the hole, causing cutting damage to the copper surface and resulting in exposed substrate scrap. This invention adds dummy plugs around the insertion hole. After curing, these resin support points are evenly distributed around the hole. During grinding, the brush is supported by these support points, avoiding direct contact between the brush and the hole edge, fundamentally eliminating the risk of damage to the copper surface at the hole opening.

[0041] 2. No changes to existing processes, low implementation cost. This invention only modifies the graphic design of the plugging aluminum sheet, adding a dummy dot plugging pattern to the original normal plugging pattern. It requires no adjustment to the resin plugging equipment, parameters, or process flow, nor does it require additional materials or procedures. The dummy dot plugging is applied, cured, and removed by grinding simultaneously with the normal plugging process, without increasing the production cycle. It is simple to implement and has low promotion costs.

[0042] 3. The parameters are reasonably designed, balancing protection effectiveness with process reliability. This invention optimizes the key parameters of the pseudo-point plugging orifice: The distance between the false dot plug hole and the edge of the plug hole is set to 1 mm to prevent ink from being squeezed into the plug hole due to printing pressure during plugging. The distance between the dummy plug hole and the normal plug hole is set to 0.5-0.8 mm to prevent resin from sticking together and oil from piling up, which would make grinding difficult. The dummy plug holes are evenly distributed at 0.5 mm intervals, and the open area covers a 3 mm range around the hole ring to ensure the uniformity and sufficiency of the grinding support. The dummy plug hole diameter is designed according to the conventional plug hole diameter of 0.35 mm and is compatible with existing tools.

[0043] The above parameter design achieves a good balance between protection effectiveness and process feasibility.

[0044] 4. Wide range of applications, compatible with various PCB products This invention is particularly suitable for high-reliability PCB products such as multilayer boards, automotive boards, power boards, and industrial control boards, which have large-diameter insertion holes on the outermost layer after lamination. It can effectively solve the scrap problem caused by grinding damage and improve the reliability of the product during welding, assembly and long-term use.

[0045] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preventing damage to plugged vias from grinding of the base copper, characterized in that, Includes the following steps: A plugging aluminum sheet is provided, wherein a normal plugging pattern is provided on the plugging aluminum sheet, and a fake plugging pattern is provided in the area around the corresponding printed circuit board plug hole; Align the plugging aluminum sheet with the printed circuit board to which the hole is to be plugged; The resin is used to plug the holes with the aluminum sheet, so that the resin ink fills the printed circuit board holes corresponding to the normal plug pattern and the peripheral board surface of the printed circuit board plug hole corresponding to the fake plug pattern. The filled resin ink is cured to form resin support points around the plug hole; The grinding process is performed, and the resin support points support the grinding brush to prevent the grinding brush from extending to the edge of the plug hole and damaging the copper surface of the hole.

2. The method for preventing base copper grinding damage to plugged vias according to claim 1, characterized in that, The dummy plug holes are evenly spaced around the corresponding positions of the plug holes, with one dummy plug hole set at every 0.5 mm interval.

3. The method for preventing base copper grinding damage to plugged vias according to claim 1, characterized in that, The distance between the dummy plug hole pattern and the edge of the plug hole is 1 mm.

4. The method for preventing base copper grinding damage to plugged vias according to claim 1, characterized in that, The distance between the dummy plug pattern and the normal plug pattern is 0.5 mm to 0.8 mm.

5. The method for preventing base copper grinding damage to plugged vias according to claim 1, characterized in that, When the area around the plug hole is empty, the dummy plug hole pattern covers at least 3 mm of the area around the plug hole ring.

6. The method for preventing base copper grinding damage to plugged vias according to claim 1, characterized in that, The aperture of the dummy plug pattern is designed according to the conventional plug aperture, which is 0.35 mm.

7. The method for preventing base copper grinding damage to plugged vias according to claim 1, characterized in that, The cured pseudo-pore-filling resin and normal pore-filling resin are removed simultaneously during the grinding step.

8. A plugging tool for use in the method according to any one of claims 1 to 7, characterized in that, The plugging tool is a plugging aluminum sheet, which has a normal plugging pattern and a fake plugging pattern in the area around the corresponding printed circuit board insertion hole.

9. The plugging tool according to claim 8, characterized in that, The dummy plug patterns are evenly distributed around the corresponding positions of the plug hole, with one dummy plug at every 0.5 mm interval; the distance between the dummy plug pattern and the edge of the plug hole is 1 mm; the distance between the dummy plug pattern and the normal plug pattern is 0.5 mm to 0.8 mm.

10. The plugging tool according to claim 8, characterized in that, When the area around the plug hole is empty, the dummy plug hole pattern covers at least 3 mm of the area around the plug hole ring; the diameter of the dummy plug hole pattern is 0.35 mm.

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