Method for manufacturing a printed circuit board and printed circuit board

Abstract

This invention discloses a method for manufacturing a printed circuit board and the printed circuit board itself. The manufacturing method includes the following steps: S1: forming micro-blind vias on a multilayer board using laser processing; S2: processing a first microchannel at the edge of the micro-blind via, the first microchannel being connected to the micro-blind via; S3: performing copper plating on the board, depositing a first metal layer on the inner walls of the micro-blind via and the first microchannel; S4: disconnecting the conductive connection between the micro-blind via and the first microchannel, and performing thickening electroplating on the multilayer board to thicken the first metal layer within the micro-blind via to a thickened metal layer; S5: performing outer layer pattern processing to form an outer layer trace layer. By disconnecting the conductive connection between the micro-blind via and the first microchannel, the plating solution can flow between the disconnected micro-blind via and the first microchannel, thereby facilitating thickening electroplating on the multilayer board and achieving metallization of the micro-blind via.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board technology, and in particular to a method for manufacturing a printed circuit board and a printed circuit board. Background Technology

[0002] With the ever-increasing demand for high-speed, high-density interconnects in applications such as 5G, AI computing power, and automotive electronics, printed circuit boards (PCBs) are evolving towards high-density interconnect (HDI). The industry generally believes that high density is reflected in four dimensions: vias, lines, layers, and surfaces. Among these, blind vias are a key technology for achieving inter-layer connectivity and saving space, and are already widely used in products such as mobile phones, automotive components, and servers. Driven by this trend, the demand for micro-blind vias (with apertures ≤100µm) is growing exponentially, especially for signal layers with fine linewidths and fine pitches.

[0003] In related technologies, as apertures are further reduced to ultra-micro blind vias (≤50µm), the difficulty of metallization increases dramatically. Large aspect ratios and obstructed plating solution flow easily lead to bubbles and uneven plating, resulting in increased resistance and decreased reliability. These technological bottlenecks keep the reliable production cost of ultra-micro blind vias high, becoming a key challenge that PCB manufacturers urgently need to overcome. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for manufacturing a printed circuit board, which disconnects the conductive connection between the ultra-micro blind via and the first microchannel, allowing the plating solution to flow between the disconnected ultra-micro blind via and the first microchannel, thereby facilitating thicker electroplating of multilayer boards and ultimately achieving metallization of the ultra-micro blind via.

[0005] The present invention further proposes a printed circuit board.

[0006] A method for manufacturing a printed circuit board according to a first aspect of the present invention includes the following steps: S1: forming micro-blind vias on a multilayer board by laser processing; S2: processing a first microchannel at the edge of the micro-blind via, the first microchannel being connected to the micro-blind via; S3: performing copper plating on the board, depositing a first metal layer on the inner walls of the micro-blind via and the first microchannel; S4: disconnecting the conductive connection between the micro-blind via and the first microchannel, and performing thickening electroplating on the multilayer board to thicken the first metal layer in the micro-blind via to a thickened metal layer; S5: performing outer layer pattern processing to form an outer layer trace layer.

[0007] According to the method for manufacturing a printed circuit board according to an embodiment of the present invention, by disconnecting the conductive connection between the micro-blind via and the first micro-channel, the plating solution can flow between the disconnected micro-blind via and the first micro-channel, thereby facilitating thicker electroplating of the multilayer board and thus realizing the metallization of the micro-blind via.

[0008] According to some embodiments of the present invention, step S4 specifically involves: ablating the first metal layer at the connection between the ultra-micro blind hole and the first micro-channel by laser processing to form a thin copper layer.

[0009] According to some embodiments of the present invention, after laser processing and ablation, the thickness of the thin copper layer in the ultra-micro blind hole is 1 / 2 to 2 / 3 of the thickness of the first metal layer.

[0010] According to some embodiments of the present invention, step S4 specifically involves: processing the first microchannel of the multilayer board to form a second microchannel, wherein the size of the second microchannel is larger than the size of the first microchannel, so as to disconnect the ultra-micro blind hole from the first microchannel through the second microchannel.

[0011] According to some embodiments of the present invention, the diameter of the ultramicro blind hole is less than or equal to 50µm.

[0012] According to some embodiments of the present invention, in step S2, the processing direction of the first micro-channel is either parallel to the axial direction of the ultra-micro blind hole or intersects with the axial direction of the ultra-micro blind hole.

[0013] According to some embodiments of the present invention, in step S2, when the processing area of ​​the first microchannel is insufficient to meet the electroplating requirements, the first microchannel is made into a through hole penetrating the multilayer board.

[0014] According to some embodiments of the present invention, the thickness of the first metal layer deposited in step S3 is 0.3-0.8µm.

[0015] According to some embodiments of the present invention, the thickness of the first metal layer after electroplating in step S4 is 15-30µm.

[0016] According to a second aspect of the present invention, the printed circuit board is prepared by the method for manufacturing the printed circuit board.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a simplified cross-sectional view of a multilayer plate stack according to Embodiment 1 of the present invention; Figure 2 This is a simplified cross-sectional view of step S1 according to Embodiment 1 of the present invention; Figure 3 This is a simplified top view of step S1 according to Embodiment 1 of the present invention; Figure 4 This is a simplified cross-sectional view of step S2 according to Embodiment 1 of the present invention; Figure 5 This is a top view of step S2 according to Embodiment 1 of the present invention; Figure 6 This is a simplified cross-sectional view of step S3 according to Embodiment 1 of the present invention; Figure 7 This is a simplified cross-sectional view of step S4 of embodiment one of the present invention; Figure 8 This is a simplified cross-sectional view of operation two in step S4 of embodiment one of the present invention; Figure 9 This is a top view of operation two of step S4 according to embodiment one of the present invention; Figure 10 This is a simplified cross-sectional view of step S5 according to Embodiment 1 of the present invention; Figure 11 This is a simplified cross-sectional view of the multilayer plate stacking according to Embodiment 2 of the present invention; Figure 12 This is a simplified cross-sectional view of step S1 according to Embodiment 2 of the present invention; Figure 13 This is a simplified top view of step S1 according to embodiment two of the present invention; Figure 14 This is a simplified cross-sectional view of step S2 according to Embodiment 2 of the present invention; Figure 15 This is a simplified top view of step S2 according to Embodiment 2 of the present invention; Figure 16 This is a simplified cross-sectional view of step S3 according to Embodiment 2 of the present invention; Figure 17 This is a simplified cross-sectional view of step S4 of embodiment two of the present invention. Figure 18 This is a top view of operation one of step S4 according to embodiment two of the present invention; Figure 19 This is a simplified cross-sectional view of step S4 of embodiment two of the present invention; Figure 20This is a simplified cross-sectional view of step S5 according to Embodiment 2 of the present invention.

[0019] Figure label: 100. Printed circuit boards; 11. Multilayer board; 12. Ultra-micro blind via; 13. First microchannel; 14. First metal layer; 15. Thin copper layer; 16. Thickened metal layer; 17. Second microchannel. Detailed Implementation

[0020] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. The embodiments of the present invention are described in detail below.

[0021] The following is for reference. Figures 1-20 A method for manufacturing a printed circuit board 100 according to an embodiment of the present invention is described, and the present invention also provides a printed circuit board 100.

[0022] Reference Figures 1-20 As shown, the present invention provides a method for manufacturing a printed circuit board 100, comprising the following steps: S1: Ultra-micro blind holes 12 are formed on the multilayer board 11 by laser processing; S2: A first micro-channel 13 is machined at the edge of the micro-blind hole 12, and the first micro-channel 13 is connected to the micro-blind hole 12. S3: Perform copper plating on the board and deposit a first metal layer 14 on the inner wall of the micro-blind hole 12 and the first micro-channel 13; S4: Disconnect the conductive connection between the micro-blind hole 12 and the first micro-channel 13, and perform thickening electroplating on the multilayer board 11 to thicken the first metal layer 14 in the micro-blind hole 12 to the thickened metal layer 16. S5: Perform outer layer graphic processing to form an outer layer routing layer.

[0023] In other words, by disconnecting the conductive connection between the micro-blind hole 12 and the first micro-channel 13, the plating solution can flow between the disconnected micro-blind hole 12 and the first micro-channel 13, thereby facilitating the thickening electroplating of the multilayer board 11 and achieving the metallization of the micro-blind hole 12.

[0024] Therefore, by first constructing a plating solution flow channel connected to the blind hole, the common problems of plating solution exchange difficulties, inability to expel bubbles, and excessively thin plating layer or even missed plating at the bottom of the hole caused by the large depth-to-diameter ratio of the ultra-micro blind hole 12 with a hole diameter ≤50µm are fundamentally solved, and high-quality and repeatable metallization of the ultra-micro blind hole 12 is achieved.

[0025] According to an optional embodiment of the present invention, referring to Figures 17-19As shown, step S4 specifically involves: ablating the first metal layer 14 at the connection between the micro-blind via 12 and the first microchannel 13 using laser processing to form a thin copper layer 15. Using laser ablation to disconnect the conductive connection offers significant advantages such as high processing precision, a small heat-affected zone, and no mechanical stress damage, without damaging the first metal layer 14 already deposited inside the blind via. Compared to mechanical cutting, this avoids problems such as tool wear, burr generation, and substrate debris contamination, making it particularly suitable for ultra-high density layouts with small blind via spacing, and increasing the number of blind vias per unit area.

[0026] Furthermore, after laser ablation, the thickness of the thin copper layer 15 within the micro-blind hole 12 is 1 / 2 to 2 / 3 of the thickness of the first metal layer 14. This configuration ensures that when the thickness of the thin copper layer 15 is 1 / 2 to 2 / 3 of the first metal layer 14, the conductive connection between the micro-blind hole 12 and the first microchannel 13 is completely severed, preventing current diversion to the microchannel during thickening electroplating and resulting in insufficient plating thickness in the blind hole. Simultaneously, it preserves a sufficiently continuous seed layer to guarantee the uniformity and adhesion of subsequent thickening electroplating. If the remaining thickness is less than 1 / 2, seed layer breakage can easily lead to incomplete plating or plating voids; if the remaining thickness is greater than 2 / 3, the conductive connection cannot be completely severed, affecting the plating effect.

[0027] According to another optional embodiment of the invention, referring to Figures 7-9 As shown, step S4 specifically involves processing the first microchannel 13 of the multilayer board 11 to form a second microchannel 17. The size of the second microchannel 17 is larger than that of the first microchannel 13, so that the micro-blind via 12 can be disconnected from the first microchannel 13 through the second microchannel 17. By controlling the processing size and position of the second microchannel 17, the second microchannel 17 can cover the first microchannel 13, removing the first metal layer 14 inside the first microchannel 13, thereby disconnecting the micro-blind via 12 from the first microchannel 13. This achieves a high conductive connection disconnection rate, and the processing is stable and controllable with good batch consistency.

[0028] Preferably, the aperture of the micro-blind via 12 is less than or equal to 50µm. This results in an exponential increase in interconnect density, with the number of interlayer interconnects per unit area increasing several times over. For the same interconnect requirements, 2-4 fewer PCB layers can be reduced, improving wiring space utilization. Furthermore, it significantly enhances high-speed signal performance, reducing parasitic capacitance and inductance to meet the requirements of 224GPAM4 signal transmission.

[0029] Furthermore, in step S2, the processing direction of the first microchannel 13 is either parallel to the axial direction of the micro-blind via 12 or intersects with the axial direction of the micro-blind via 12. This flexible channel processing direction design can adapt to different PCB layout requirements. When the parallel direction is used, the plating solution flow path is shortest, resistance is lowest, bubble removal efficiency is highest, and the ratio of plating thickness at the bottom of the blind via to the thickness at the via opening can reach over 0.95, resulting in optimal plating uniformity. When the intersecting direction is used, one microchannel can simultaneously provide plating solution channels for multiple adjacent blind vias, significantly saving wiring space and increasing PCB wiring density. This is particularly suitable for processing array-type micro-blind vias 12 in BGA packaging areas.

[0030] Furthermore, in step S2, when the processing area of ​​the first microchannel 13 is insufficient to meet the electroplating requirements, the first microchannel 13 is fabricated as a through-hole penetrating the multilayer board 11. That is, upgrading the microchannel to a through-hole can form a vertically connected plating solution circulation channel, completely solving the problem of plating solution exchange for thick plates and high aspect ratio ultra-micro blind holes 12. The through-hole structure allows the electroplating solution to form forced convection under pressure, completely eliminating the bubble retention phenomenon inside the blind hole. Even for ultra-micro blind holes 12 with a depth of up to 60µm, a uniform metallized plating layer can be achieved. Thus, when the processing area of ​​the first microchannel 13 is insufficient to meet the electroplating requirements, fabricating the first microchannel 13 as a through-hole penetrating the multilayer board 11 can significantly improve the processing yield of ultra-micro blind holes 12.

[0031] Preferably, the thickness of the first metal layer 14 deposited in step S3 is 0.3-0.8 µm. When the thickness of the first metal layer 14 is between 0.3-0.8 µm, the electroless copper layer exhibits both good conductivity and adhesion. When the thickness is 0.3 µm, a continuous, pinhole-free conductive film can be formed, meeting the seed layer requirements for subsequent electroplating. When the thickness exceeds 0.8 µm, the internal stress of the electroless copper layer increases significantly, making it prone to plating peeling and delamination, while also increasing unnecessary material costs. This improves the adhesion between the electroless copper layer and the substrate, preventing blistering and peeling, and providing a solid foundation for subsequent thicker electroplating.

[0032] Preferably, the thickness of the first metal layer 14 after thickening electroplating in step S4 is 15-30µm. When the thickness of the first metal layer 14 after thickening electroplating is in the range of 15-30µm, the resistance change rate of the micro-blind via 12 is significantly reduced, with no open circuit or short circuit phenomena, resulting in excellent long-term reliability. The minimum thickness of 15µm ensures that the micro-blind via 12 has sufficient current carrying capacity to meet the transmission requirements of high-speed differential signals; the maximum thickness of 30µm avoids the problems of orifice protrusion and reduced pattern accuracy caused by excessively thick plating. This plating thickness is adopted.

[0033] According to a second aspect embodiment of the present invention, the printed circuit board 100 is manufactured by any of the above-described methods for manufacturing printed circuit boards 100. This configuration provides the printed circuit board 100 with comprehensive advantages, including high metallization quality of the micro-blind vias 12, good signal transmission performance, high reliability, and low cost, thus meeting the urgent needs of next-generation electronic systems for high-speed, high-density, and high-reliability interconnections.

[0034] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used 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.

[0035] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0036] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for manufacturing a printed circuit board, characterized in that, Includes the following steps: S1: Ultra-micro blind holes are formed on a multilayer board by laser processing; S2: A first micro-channel is machined at the edge of the micro-blind hole, and the first micro-channel is connected to the micro-blind hole; S3: Perform copper plating on the board, depositing a first metal layer on the inner wall of the ultra-micro blind hole and the first micro-channel; S4: Disconnect the conductive connection between the micro-blind hole and the first micro-channel, and perform thickening electroplating on the multilayer board to thicken the first metal layer in the micro-blind hole to a thickened metal layer; S5: Perform outer layer graphic processing to form an outer layer routing layer.

2. The method for manufacturing a printed circuit board according to claim 1, characterized in that, Step S4 specifically involves: ablating the first metal layer at the connection between the ultra-micro blind hole and the first micro-channel through by laser processing to form a thin copper layer.

3. The method for manufacturing a printed circuit board according to claim 2, characterized in that, After laser ablation, the thickness of the thin copper layer inside the micro-blind hole is 1 / 2 to 2 / 3 of the thickness of the first metal layer.

4. The method for manufacturing a printed circuit board according to claim 1, characterized in that, Step S4 specifically involves processing the first microchannel of the multilayer board to form a second microchannel, wherein the size of the second microchannel is larger than the size of the first microchannel, so as to disconnect the ultra-micro blind hole from the first microchannel through the second microchannel.

5. The method for manufacturing a printed circuit board according to any one of claims 1-4, characterized in that, The diameter of the micro-blind hole is less than or equal to 50µm.

6. The method for manufacturing a printed circuit board according to any one of claims 1-4, characterized in that, In step S2, the processing direction of the first micro-channel is either parallel to the axial direction of the micro-blind hole or intersects with the axial direction of the micro-blind hole.

7. The method for manufacturing a printed circuit board according to any one of claims 1-4, characterized in that, In step S2, when the processing area of ​​the first micro-channel is insufficient to meet the electroplating requirements, the first micro-channel is made into a through hole penetrating the multilayer board.

8. The method for manufacturing a printed circuit board according to any one of claims 1-4, characterized in that, The thickness of the first metal layer deposited in step S3 is 0.3-0.8µm.

9. The method for manufacturing a printed circuit board according to any one of claims 1-4, characterized in that, In step S4, the thickness of the first metal layer after electroplating is 15-30µm.

10. A printed circuit board, characterized in that, The printed circuit board is manufactured by the method of manufacturing the printed circuit board according to any one of claims 1-9.

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