Method for manufacturing a printed circuit board and printed circuit board

Abstract

This invention discloses a method for manufacturing a printed circuit board (PCB). The method includes the following steps: printing washable ink at predetermined drilling positions on a prepreg; laminating the prepreg printed with the washable ink to a core board and a first metal layer to form a multilayer board; etching windows in the first metal layer on the surface of the multilayer board to expose a substrate area corresponding to the predetermined drilling positions; drilling holes in the substrate area to form through-holes penetrating the multilayer board; removing the washable ink from the through-holes; and performing copper plating on the through-holes. By pre-setting the washable ink, the burrs generated at the drilling openings adhere to the washable ink and detach from the board along with the washable ink during ink removal, eliminating residual burrs at the openings from the source, reducing various reliability risks caused by burrs, and ensuring that the finished product meets the requirements of high-frequency and high-speed products.

Description

Technical Field

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

[0002] In the printed circuit board (PCB) manufacturing process, drilling is a crucial step in achieving interlayer interconnection. If burrs remain at the hole opening after drilling, it will cause rough hole walls, prevent uniform copper metallization, weaken signal transmission strength, and generate electromagnetic interference. It will also reduce the mechanical strength of the board, and in severe cases, cause hole wall delamination, increasing the probability of short circuits and poor soldering. Burrs often exist in the form of metal or glass fiber residues. In high-density interconnection or micro-via processing scenarios, they are more likely to form volcano-like burrs, directly causing through-hole failure or scrapping the entire board. Therefore, burr problems have become one of the major reliability challenges faced by PCB manufacturers.

[0003] In related technologies, the industry typically maintains strict control over processing parameters such as drill bit material selection, rotation speed, and feed rate. Post-processing is also carried out using backing plates, cover plates, or dedicated deburring devices. Some factories with advanced production capacity equip themselves with automatic deburring components to automatically remove burrs, thereby improving product yield and processing efficiency. However, with the rapid development of high-frequency and high-speed applications such as 5G and 6G, the industry's requirements for micro-hole processing quality continue to rise. The technical difficulty and processing cost of burr control are increasing simultaneously, becoming a bottleneck restricting capacity improvement and product reliability. How to improve the burr problem at the borehole opening during the drilling process is a technical challenge that major manufacturers urgently need to solve. 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 printed circuit boards, which involves pre-setting a washable ink so that the burrs generated during drilling adhere to the washable ink and detach from the board along with the washable ink during ink removal, thereby eliminating residual burrs at the hole openings from the source.

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

[0006] According to a first aspect of the present invention, a method for manufacturing a printed circuit board includes the following steps: printing washable ink at predetermined drilling positions on a prepreg; laminating the prepreg printed with the washable ink to a core board and a first metal layer to form a multilayer board; etching a window in the first metal layer on the surface of the multilayer board to expose a substrate area corresponding to the predetermined drilling position; drilling the substrate area to form a through hole penetrating the multilayer board; removing the washable ink from the through hole; and performing copper plating on the through hole.

[0007] According to the method for manufacturing printed circuit boards according to embodiments of the present invention, by pre-setting washable ink, the burrs generated by drilling are attached to the washable ink and detached from the board along with the washable ink during the ink removal process, thereby eliminating residual burrs at the hole openings from the source, reducing various reliability risks caused by burrs, and enabling the finished product to meet the usage requirements of high-frequency and high-speed products.

[0008] According to some embodiments of the present invention, before printing washable ink on the prepreg, the method further includes: punching and positioning the prepreg.

[0009] According to some embodiments of the present invention, before etching and opening windows in the multilayer board, the method further includes: applying a film to the multilayer board for exposure, thereby exposing the preset drilling positions.

[0010] According to some embodiments of the present invention, the step of removing the washable ink at the through-hole further includes: removing the film on both sides of the multilayer board.

[0011] According to some embodiments of the present invention, the window area is a circular blank area.

[0012] According to some embodiments of the present invention, the step of printing washable ink at the preset drilling positions of the prepreg sheets further includes: printing washable ink at the preset drilling positions of the two prepreg sheets; the step of pressing the prepreg sheets printed with the washable ink with the core board and the first metal layer further includes: stacking and pressing the two prepreg sheets printed with the washable ink on both sides of the core board and having a first metal layer disposed on the outer side.

[0013] According to some embodiments of the present invention, the printing thickness of the washable ink is 1 / 3 to 1 / 2 of the thickness of the prepreg.

[0014] According to some embodiments of the present invention, the size of the window area formed by etching is 1-2 mil larger than the diameter of the drill bit used for drilling.

[0015] According to a second aspect of the present invention, the printed circuit board is manufactured using the aforementioned preparation method.

[0016] 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

[0017] 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 structural diagram of a prepreg according to an embodiment of the present invention; Figure 2 This is step one of the methods for preparing a printed circuit board according to an embodiment of the present invention; Figure 3 This is step two of the method for preparing a printed circuit board according to an embodiment of the present invention; Figure 4 This is step three of the method for preparing a printed circuit board according to an embodiment of the present invention; Figure 5 This is step four of the method for preparing a printed circuit board according to an embodiment of the present invention; Figure 6 This is step five of the method for preparing a printed circuit board according to an embodiment of the present invention; Figure 7 This is step six of the method for preparing a printed circuit board according to an embodiment of the present invention; Figure 8 This is step seven of the method for preparing a printed circuit board according to an embodiment of the present invention; Figure 9 This is step eight of the method for preparing a printed circuit board according to an embodiment of the present invention; Figure label: 100. Printed circuit boards; 11. Prepreg; 12. Positioning hole; 13. Washable ink; 14. First metal layer; 15. Mask; 16. Through hole; 17. Second metal layer; 18. Core board. Detailed Implementation

[0018] 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.

[0019] The following is for reference. Figures 1-9 The invention describes a method for manufacturing a printed circuit board 100 according to an embodiment of the invention, and also provides a printed circuit board 100.

[0020] Reference Figures 1-9 As shown, the method for preparing the printed circuit board 100 according to an embodiment of the present invention includes the following steps: Washable ink 13 is printed at the preset drilled positions of the prepreg 11; A prepreg 11 printed with washable ink 13 is pressed together with a core board 18 and a first metal layer 14 to form a multilayer board. After ink printing is completed, the prepreg 11 with washable ink 13, the core board 18, and the first metal layer 14 are precisely aligned and arranged according to the designed stacking structure, and sent into a pressing equipment to complete high-temperature and high-pressure pressing. After the prepreg 11 is heated and cured, it is tightly bonded to the core board 18 and the first metal layer 14 to form a complete multilayer board. The printed washable ink 13 is stably retained in the preset drilling position below the first metal layer 14, and does not spread widely with the normal glue flow of the prepreg 11, nor does it damage the bonding strength and insulation performance between layers.

[0021] The first metal layer 14 on the surface of the multilayer board is etched to create a window, exposing the substrate area corresponding to the preset drilling position. The substrate area is then drilled to form a through-hole 16 penetrating the multilayer board. After the multilayer board is fabricated, the first metal layer 14 on the surface of the multilayer board is etched to remove the first metal layer 14 at the preset drilling position, exposing the substrate area below. This allows subsequent drilling operations to directly target the substrate surface, preventing the drill bit from directly cutting the first metal layer 14 and causing a large amount of copper residue to accumulate at the hole opening, thus reducing the source of burr generation from the processing front end. After the window is created, drilling is performed along the center of the windowed area. The drill bit penetrates the multilayer board at a uniform speed in the vertical direction, forming a through-hole 16 penetrating the upper and lower surfaces of the multilayer board. Glass fiber residue and substrate burrs generated during drilling adhere to the washable ink 13 surface at the hole opening position, rather than firmly adhering to the substrate hole edge to form difficult-to-remove volcano-like burrs.

[0022] The washable ink 13 at the through-hole 16 is removed, and the through-hole 16 is then plated with copper. After drilling, the board is washed away using a matching washing solution to dissolve and remove the pre-printed washable ink 13. Burrs and processing debris adhering to the ink surface are removed from the board along with the ink, keeping the openings of the through-hole 16 smooth and clean, without any residual burrs. After the ink is removed, the through-hole 16 is plated with copper to form a continuous and uniform second metal layer 17 on the inner wall of the through-hole 16, achieving interlayer electrical interconnection of the multilayer board. Because there are no burr protrusions at the openings, the overall flatness of the hole wall is high. The second metal layer 17 formed by copper plating has uniform thickness and stable adhesion, which can effectively reduce signal transmission loss and electromagnetic interference, avoid reliability problems such as hole wall delamination, short circuits, and poor welding, and adapt to the stringent requirements of high-frequency and high-speed products for micro-hole processing quality.

[0023] In other words, a multilayer board is formed by laminating a prepreg 11 printed with washable ink 13 to a core board 18 and a first metal layer 14. The first metal layer 14 on the surface of the multilayer board is etched to create windows, exposing the substrate area corresponding to the preset drilling positions. Drilling is then performed on the substrate area to form through-holes 16 penetrating the multilayer board. After removing the washable ink 13 from the through-holes 16, copper plating is applied to the through-holes 16. The entire process, by pre-setting the washable ink 13, allows the burrs generated during drilling to adhere to the ink structure. During ink removal, these burrs detach from the board along with the ink, eliminating residual burrs at the hole openings from the source, reducing various reliability risks caused by burrs, and ensuring the finished product meets the requirements of high-frequency and high-speed products.

[0024] Therefore, by pre-setting the washable ink 13, the burrs generated during drilling are attached to the washable ink 13 and detached from the board along with the washable ink 13 during ink removal, thus eliminating residual burrs at the hole opening from the source, reducing various reliability risks caused by burrs, and enabling the finished product to meet the usage requirements of high-frequency and high-speed products.

[0025] Reference Figure 2 As shown, before printing washable ink 13 on the prepreg 11, the process also includes punching and positioning the prepreg 11. By punching positioning holes 12 on the prepreg 11, the positioning holes 12 can form a precise alignment reference on the prepreg 11, ensuring that the subsequent ink printing position corresponds completely with the designed drilling position, avoiding ink not covering the hole area due to positional misalignment, ensuring the stability of the deburring effect, and adapting to the alignment process in mass production, thus improving the overall processing efficiency.

[0026] Reference Figure 5 and Figure 6 As shown, before etching and opening windows on the multilayer board, the process also includes: applying a film to the multilayer board for exposure, thereby exposing the preset drilling positions. The film can cover the entire area of ​​the first metal layer 14 on the surface of the board, and the drilling positions to be opened are accurately exposed through the exposure and development process, providing a protective mask 15 for subsequent etching processes, preventing the first metal layer 14 in non-drilled areas from being etched and damaged, and ensuring the accuracy of the window opening position and the integrity of the circuit layer.

[0027] Reference Figure 7 and Figure 8 As shown, the step of removing the washable ink 13 at the through-hole 16 also includes: removing the film on both sides of the multilayer board. The washing process can be carried out using a matching chemical solution, which can simultaneously decompose the ink and film material, allowing both to completely detach from the board surface. At the same time, it also removes the burrs and debris attached to the hole openings from the board, eliminating the need for an additional deburring process, simplifying the processing flow, ensuring the cleanliness of the hole openings and the board surface, and providing a good processing foundation for the subsequent copper plating process.

[0028] In other words, while removing the washable ink 13 from the through hole 16, it is also necessary to remove the film on both sides of the multilayer board in order to perform copper plating on the through hole 16.

[0029] The window area is a circular blank area. The circular blank area matches the circular outline of the drill hole, and the first metal layer 14 on the surface can be removed evenly along the circumference of the drill hole. This ensures that the drilling operation is carried out entirely in the substrate area without the first metal layer 14, avoiding the formation of copper burrs when the drill bit drills the first metal layer 14. At the same time, the circular structure distributes the force evenly, which can reduce the probability of the substrate at the hole opening cracking or delamination during drilling, and improve the hole opening forming quality.

[0030] The step of printing washable ink 13 at the preset drilling positions of the prepreg 11 further includes: printing washable ink 13 at the preset drilling positions of the two prepregs 11. Two prepregs 11 are selected and printed separately. In the area of ​​each prepreg 11 corresponding to the subsequent drilling position, washable ink 13 of a preset thickness is printed. The ink printing positions on the two prepregs 11 correspond to each other to ensure that the stacked layers can completely overlap with the final designed drilling positions.

[0031] The step of laminating the prepreg 11 printed with washable ink 13 to the core board 18 and the first metal layer 14 further includes: stacking and laminating two prepregs 11 printed with washable ink 13 on both sides of the core board 18, with the first metal layer 14 on the outer side. When performing multilayer board lamination, the core board 18 is first placed in the middle of the laminated structure, then the two printed prepregs 11 are laid on the upper and lower surfaces of the core board 18, with the area with washable ink 13 facing the drilling entrance direction on the outer side of the board. Finally, the first metal layer 14 is covered on the outer side of each of the two prepregs 11.

[0032] In this way, the openings at both ends of the through-hole 16 come into contact with the washable ink 13. The glass fiber debris and substrate burrs generated during drilling will adhere to the surface of the ink layer, rather than directly adhering to the edge of the board substrate and the first metal layer 14. In the subsequent ink removal process, the washable ink 13 on both sides of the multilayer board will be dissolved and removed simultaneously by the removal solution. The burrs and processing debris adhering to the ink will also detach from the board along with the ink, achieving simultaneous cleaning of the burrs at both ends of the through-hole 16. This avoids the problem of burrs remaining at the opening on the other side when ink is applied on one side, ensuring that the flatness of the openings at both ends of all through-holes 16 on the entire board is consistent.

[0033] The print thickness of the washable ink 13 is 1 / 3 to 1 / 2 of the thickness of the prepreg 11. Thus, within this thickness range, the ink layer will not experience large-scale flow and diffusion due to extrusion during subsequent high-temperature lamination, and can be stably maintained at the preset drilling position. During lamination, the prepreg 11 will experience a certain degree of adhesive flow; this thickness setting prevents the ink from being dispersed by the flow, ensuring that the ink always covers the corresponding position of the hole. At the same time, sufficient thickness can accommodate burr residue generated during drilling, ensuring that the burrs completely detach from the board along with the ink. Controlling the thickness within this range will not affect the normal adhesive flow and interlayer bonding force of the prepreg 11, ensuring the lamination reliability and interlayer adhesion strength of the multilayer board.

[0034] The size of the etched window area is 1-2 mil larger than the diameter of the drill bit used for drilling. This dimensional allowance can compensate for the alignment tolerance during the drilling process, ensuring that the drill bit falls completely within the blank area formed by the window and does not contact the surrounding first metal layer 14 throughout the process. This avoids metal residue from the drill bit cutting the first metal layer 14 adhering to the hole opening, reducing the possibility of burr generation from the front end of the processing. At the same time, the 1-2 mil allowance will not excessively occupy the surface space of the board and will not affect the layout design of the surrounding circuits and pads, adapting to the processing requirements of printed circuit boards 100 with high-density wiring.

[0035] One mil is one-thousandth of an inch, that is, 1 mil = 0.0254 millimeters.

[0036] According to a second aspect embodiment of the present invention, the printed circuit board 100 is manufactured by a preparation method. Thus, the printed circuit board 100 manufactured by the above-described preparation method has no residual burrs at the openings of the through holes 16, smooth and flat hole walls, and a uniform thickness of the second metal layer 17 formed after copper plating. It exhibits low signal transmission loss and minimal electromagnetic interference, high mechanical strength at the hole locations, no risk of hole wall delamination, excellent soldering yield, and superior long-term reliability. It can be widely used in fields with stringent reliability requirements for the printed circuit board 100, and is particularly suitable for high-speed, high-frequency communication products with numerous drilled holes.

[0037] 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.

[0038] 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.

[0039] 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, The preparation method includes the following steps: Print washable ink at the pre-drilled locations on the prepreg; The prepreg printed with the washable ink is pressed together with the core board and the first metal layer to produce a multilayer board; The first metal layer on the surface of the multilayer board is etched to create a window, exposing the substrate area corresponding to the preset drilling position; Drilling is performed on the substrate area to form through holes that penetrate the multilayer board; Remove the washable ink from the through holes and perform copper plating on the through holes.

2. The method for preparing a printed circuit board according to claim 1, characterized in that, Before printing washable inks on the prepreg, the process also includes: Punch holes to position the prepreg.

3. The method for preparing a printed circuit board according to claim 1, characterized in that, Before etching windows into the multilayer board, the following steps are also included: The step of applying a film to the multilayer board to expose the preset drilling positions.

4. The method for preparing a printed circuit board according to claim 3, characterized in that, The step of removing the washable ink from the through-hole also includes: Remove the film from both sides of the multilayer board.

5. The method for preparing a printed circuit board according to claim 1, characterized in that, The window area is a circular blank area.

6. The method for preparing a printed circuit board according to claim 1, characterized in that, The step of printing washable ink at the preset drilling positions of the prepreg also includes: Washable ink is printed at the preset drilled locations on the two prepreg sheets; The step of laminating the prepreg printed with the washable ink to the core board and the first metal layer further includes: Two prepreg sheets printed with the washable ink are respectively placed on both sides of the core board, with a first metal layer on the outer side, and then stacked and pressed together.

7. The method for preparing a printed circuit board according to claim 1, characterized in that, The print thickness of the washable ink is 1 / 3 to 1 / 2 of the thickness of the prepreg.

8. The method for preparing a printed circuit board according to claim 1, characterized in that, The size of the window area formed by etching is 1-2 mil larger than the diameter of the drill bit used for drilling.

9. A printed circuit board, characterized in that, The printed circuit board is prepared by any one of claims 1-8.

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