Circuit board manufacturing method and circuit board

Abstract

The application relates to the technical field of circuit board manufacturing, and discloses a circuit board manufacturing method and a circuit board. The circuit board manufacturing method comprises the following steps: providing a to-be-drilled substrate, performing windowing on the outer copper layer of the to-be-drilled substrate to remove the hole opening copper layer, and the windowing aperture is equal to the finished product aperture; performing laser thermal processing to burn and expand the hole, and the burn and expand aperture is smaller than the windowing aperture; and performing laser cold processing to round cut to obtain a deep micro blind hole, and the round cut aperture is smaller than the windowing aperture and larger than the burn and expand aperture. After the windowing is performed on the outer copper layer of the to-be-drilled substrate, the laser thermal processing is first used to burn and expand the hole to remove most of the medium layer in the hole, and then the laser cold processing is used to perform round cutting to remove the remaining medium layer in the hole, so that the deep micro blind hole is obtained. In the above process, the high processing efficiency of the laser thermal processing and the high processing precision of the laser cold processing can improve the hole wall quality after the deep micro blind hole is processed, while ensuring the processing efficiency.

Description

Technical Field

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

[0002] Currently, deep micro-blind vias on circuit boards are typically machined using carbon dioxide (CO2) laser drilling. However, this often results in rough hole walls after machining. Summary of the Invention

[0003] In view of this, embodiments of this application provide a circuit board manufacturing method and a circuit board to solve the problem of rough hole walls.

[0004] The first aspect of this application discloses a method for manufacturing a circuit board, comprising: A substrate to be drilled is provided, and a window is made in the outer copper layer of the substrate to be drilled to remove the copper layer at the hole opening, and the diameter of the window opening is equal to the diameter of the finished hole. The hole is enlarged by laser thermal processing, and the diameter of the enlarged hole is smaller than the diameter of the window opening. Laser cold processing is used to perform circular cutting to obtain deep micro blind holes. The diameter of the circularly cut hole is smaller than the diameter of the window opening and larger than the diameter of the burn-through hole.

[0005] The beneficial effects of the circuit board manufacturing method provided in this application are as follows: After opening a window in the outer copper layer of the substrate to be drilled, a laser thermal processing method is first used to burn and enlarge the hole to remove most of the dielectric layer inside the hole. Then, a laser cold processing method is used to perform circular cutting to remove the remaining dielectric layer inside the hole, thereby obtaining a deep micro blind via. In the above circuit board manufacturing process, the high processing efficiency of the laser thermal processing method and the high processing precision of the laser cold processing method can improve the hole wall quality after the deep micro blind via is processed while ensuring processing efficiency.

[0006] In some embodiments, the use of laser thermal processing to enlarge holes by burning includes: enlarging holes by burning with a carbon dioxide laser; and / or, the use of laser cold processing to perform circular cutting includes: performing circular cutting with an ultraviolet laser.

[0007] In some embodiments, the diameter of the burn-through hole is 0.05 mm to 0.1 mm smaller than the diameter of the window opening.

[0008] In some embodiments, the circular cut diameter is 0.01mm-0.02mm smaller than the window opening diameter, and the circular cut diameter is 0.01mm-0.02mm larger than the sintering diameter.

[0009] In some embodiments, during the borehole enlargement process, the coverage area of ​​the laser aperture is 0.011 mm. 2 -0.020mm 2 .

[0010] In some embodiments, circular cutting is performed using a laser cold processing method, which includes: the laser beam drills a hole at one point each time, and then moves to the next point, and the laser beam travels in a circle to achieve circular cutting.

[0011] In some embodiments, circular cutting is performed using laser cold processing, including: The laser beam travels in multiple circles continuously. As the laser beam moves in circles, the focal point moves downwards layer by layer along the depth direction of the material to achieve circular cutting; or, The laser beam is a ring laser beam, and circular cutting is achieved by rotating the ring laser beam.

[0012] In some embodiments, when circular cutting is performed using laser cold processing, the depth of the inner copper layer of the substrate to be drilled is less than 0.0005 mm.

[0013] In some embodiments, the outer copper layer of the substrate to be drilled is opened by etching; or, the outer copper layer of the substrate to be drilled is opened by machining.

[0014] The second aspect of this application discloses a circuit board manufactured by the circuit board manufacturing method described in the first aspect.

[0015] The circuit board adopts any one or more embodiments of the circuit board manufacturing method described above, and therefore has the beneficial effects of the embodiments described above, which will not be repeated here.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a circuit board manufacturing method provided in some embodiments of this application; Figure 2 This is a cross-sectional view of a substrate to be drilled provided in some embodiments of this application; Figure 3 yes Figure 2 The cross-sectional view of the substrate to be drilled after the window has been opened; Figure 4 yes Figure 3 The top view of the substrate to be drilled during the enlargement of the hole by wire bonding. Figure 5 yes Figure 4 The cross-sectional view of the substrate to be drilled after the hole has been enlarged by wire wrapping. Figure 6 yes Figure 5 The top view shown is taken during the circular cutting process of the substrate to be drilled. Figure 7 yes Figure 6 The cross-sectional view shown is of the substrate to be drilled after circular cutting. Figure 8 This is a comparison diagram of the coverage area of ​​the laser aperture in related technologies and the coverage area of ​​the laser aperture in this application.

[0019] The markings in the diagram mean: 10. Substrate to be drilled; 11. Outer copper layer; 12. Dielectric layer; 13. Inner copper layer; 14. Deep micro blind hole. Detailed Implementation

[0020] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0022] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0025] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0026] In the description of the embodiments of this application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of this application 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 the embodiments of this application.

[0027] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0028] In circuit board manufacturing, deep micro-blind vias are often fabricated to achieve high-density, short-path electrical interconnection between the surface layer and the deep inner layer without penetrating the entire board. This improves wiring density, optimizes high-speed signal integrity, and facilitates device miniaturization.

[0029] Currently, in laser processing of deep micro-blind holes, after creating a window in the outer copper layer, a carbon dioxide (CO2) laser is used to drill the dielectric layer at the window opening to obtain the deep micro-blind hole. The dielectric layer is typically a prepreg, also known as a PP sheet, which is composed of resin (mainly epoxy resin, but also including bismaleimide triazine resin, cyanate ester resin, polyphenylene ether resin, polyimide resin, etc.) and reinforcing materials (mainly fiberglass cloth). Under heat and pressure, the prepreg softens, flows, and eventually cures, serving both adhesive and insulating functions.

[0030] Due to the difference in laser absorption and ablation rates between resin and glass fiber, during CO2 laser drilling, resin is often preferentially removed, leaving glass fiber ends remaining or exposed. This problem is exacerbated by the denser distribution of glass fibers in some prepreg sizes. Furthermore, for prepregs located close to the bottom of the hole, the combined effects of copper surface reflection, the heat-affected zone, and residual medium make it more difficult to uniformly remove glass fiber residue from the hole wall, leading to issues such as blind holes, rough hole walls, and subsequent plating defects.

[0031] To address the aforementioned problems, this application proposes a circuit board manufacturing method and a circuit board.

[0032] This application addresses the problem of rough hole walls in deep micro blind holes. During the hole enlargement stage, the laser thermal processing range is controlled by reducing the drill bit data. Then, based on the hole diameter, medium thickness, and machine capability, a laser cold processing method is selected for circular cutting to obtain the deep micro blind hole. This improves the problems of glass fiber residue and rough hole walls while meeting the target hole diameter requirements and ensuring processing efficiency.

[0033] Please refer to Figure 1 The first aspect of this application provides a method for manufacturing a circuit board, comprising: S100, please refer to Figure 2 and Figure 3 A substrate 10 to be drilled is provided, and a window is made in the outer copper layer 11 of the substrate 10 to remove the copper layer at the hole opening, and the opening diameter D1 is equal to the finished hole diameter.

[0034] Optionally, the substrate 10 to be drilled is a multilayer substrate (i.e., including at least three copper layers), specifically, the substrate 10 to be drilled includes two outer copper layers 11, at least two dielectric layers 12, and at least one inner copper layer 13. For example, the substrate 10 to be drilled may include two outer copper layers 11, two dielectric layers 12, and one inner copper layer 13; or, the substrate 10 to be drilled may include two outer copper layers 11, three dielectric layers 12, and two inner copper layers 13. The dielectric layers 12 are disposed between the outer copper layers 11 and the inner copper layers 13, and between the inner copper layers 13. Of course, the substrate 10 to be drilled may also be a two-layer substrate (i.e., including two copper layers).

[0035] Optionally, the dielectric layer 12 is a prepreg, also known as a PP (Prepreg) sheet, which is composed of resin (mainly epoxy resin, and also bismaleimide triazine resin, cyanate resin, polyphenylene ether resin, polyimide resin, etc.) and reinforcing material (mainly fiberglass cloth). Under heating and pressure, the prepreg softens, flows and eventually cures, playing a bonding and insulating role between the outer copper layer 11 and the inner copper layer 13.

[0036] Optionally, an etching method can be used to create windows in the outer copper layer 11 of the substrate 10 to be drilled. For example, by applying a dry film to the outer copper layer 11 of the substrate 10 to be drilled, and after exposure and development, etching is used to remove the copper layer at the hole opening that is not covered by the dry film; or, by coating a wet film on the outer copper layer 11 of the substrate 10 to be drilled, and after exposure and development, etching is used to remove the copper layer at the hole opening that is not covered by the wet film.

[0037] Alternatively, a mechanical processing method can be used to create a window in the outer copper layer 11 of the substrate 10 to be drilled. For example, the copper layer at the hole opening can be removed by laser processing; or, the copper layer at the hole opening can be removed by mechanical controlled-depth drilling.

[0038] The opening diameter D1 is equal to the finished hole diameter. That is, the opening diameter D1 is processed according to the diameter of the final finished hole. After the outer copper layer 11 is opened, the outer copper layer 11 will not be processed again, and the opening size will not change. The opening shape is circular.

[0039] It should be noted that the window opening diameter D1 is equal to the finished product diameter, but it is not limited to being equal in a strict sense. That is, the window opening diameter D1 can also be close to the finished product diameter.

[0040] S200, please refer to Figure 4 and Figure 5 The hole is enlarged by laser thermal processing, and the diameter of the enlarged hole, D2, is smaller than the diameter of the window opening, D1.

[0041] Among them, laser thermal processing has high power density and relatively long pulse width. The material is first heated, then melted, then vaporized, and finally blown away by auxiliary gas.

[0042] Alternatively, the laser thermal processing method can be carbon dioxide laser processing, that is, using a carbon dioxide laser to burn around and enlarge the hole. Carbon dioxide lasers are low in cost and fast in processing, which can improve processing efficiency. Of course, laser thermal processing methods can also be carbon monoxide laser processing or fiber laser processing, etc.

[0043] Burn-around hole enlargement refers to the process where a laser beam starts from the center of the hole and removes material layer by layer along a preset path (such as a circle or a spiral) until the hole diameter and depth reach the target dimensions.

[0044] The shape of the enlarged hole after firing is circular. Optionally, the firing hole diameter D2 is 0.05mm-0.1mm smaller than the window opening diameter D1. For example, the firing hole diameter D2 is 0.05mm, 0.055mm, 0.06mm, 0.065mm, 0.07mm, 0.075mm, 0.08mm, 0.085mm, 0.09mm, 0.095mm, or 0.1mm smaller than the window opening diameter D1.

[0045] S300, please refer to Figure 6 and Figure 7 Laser cold processing is used to perform circular cutting to obtain deep micro blind holes 14. The circular cutting hole diameter D3 is smaller than the window opening diameter D3 and larger than the burn-through hole diameter D2.

[0046] Among them, laser cold processing has a short wavelength and short pulse width, and the photon energy is higher than the material bond energy, which directly decomposes / sublimates the material into plasma or small molecules, and the crystal lattice does not have time to conduct heat.

[0047] Alternatively, the laser cold processing method can be ultraviolet laser processing, that is, using ultraviolet lasers for circular cutting. Ultraviolet lasers offer high precision and low heat loss, meeting high yield requirements. Of course, laser cold processing methods can also include femtosecond infrared laser processing or picosecond infrared laser processing, etc.

[0048] Optionally, there are two circular cutting methods. One is the single-point drilling method, where the laser beam drills at one point each time (creating a deep hole in one go), and then moves to the next point, completing one circle to achieve the circular cutting process. The other is the nested circular cutting method, where the laser beam continuously makes multiple circles. As the laser beam moves in circles, the focal point moves downwards layer by layer along the material depth direction to achieve the circular cutting process; alternatively, the laser beam is a ring-shaped laser beam, and the circular cutting process is achieved through the rotation of the ring-shaped laser beam.

[0049] Optionally, the circular aperture D3 is 0.01mm-0.02mm smaller than the window aperture D3. For example, the circular aperture D3 is 0.01mm, 0.011mm, 0.012mm, 0.013mm, 0.014mm, 0.015mm, 0.016mm, 0.017mm, 0.018mm, 0.019mm, or 0.02mm smaller than the window aperture D3.

[0050] Optionally, the circular cut diameter D3 is 0.01mm-0.02mm larger than the sintering diameter D2. For example, the circular cut diameter D3 is 0.01mm, 0.011mm, 0.012mm, 0.013mm, 0.014mm, 0.015mm, 0.016mm, 0.017mm, 0.018mm, 0.019mm, or 0.02mm larger than the sintering diameter D2.

[0051] In laser processing, the laser is processed by making a small circle of a certain diameter (e.g., 0.02mm-0.05mm) around the hole. Therefore, after processing one circle, a virtual ring is formed. The outer diameter of the virtual ring is the circular cutting hole diameter D3, and the inner diameter of the virtual ring is D4. D4 is smaller than the cutting hole diameter D2.

[0052] It should be noted that, due to the energy attenuation inside the material during laser processing and the combined effect of the physical mechanisms during material removal, the deep micro-blind hole 14 is tapered with a larger upper diameter and a smaller lower diameter. That is, the deep micro-blind hole 14 has an upper diameter and a lower diameter.

[0053] The circuit board manufacturing method provided in this application involves creating a window in the outer copper layer 11 of the substrate 10 to be drilled. First, a laser thermal processing method is used to enlarge the hole by burning around it to remove most of the dielectric layer 12 inside the hole. Then, a laser cold processing method is used to perform circular cutting to remove the remaining dielectric layer 12 inside the hole, thereby obtaining a deep micro-blind via 14. In the above circuit board manufacturing process, the high processing efficiency of the laser thermal processing method and the high processing precision of the laser cold processing method can improve the hole wall quality after the deep micro-blind via 14 is processed, while ensuring processing efficiency.

[0054] In some embodiments, the burn-through aperture D2 is 0.05mm-0.1mm smaller than the window aperture D1. This ensures that the lower aperture is within the required range while burning the prepreg as thoroughly as possible, thereby reducing the phenomenon of coarse glass fibers on the aperture wall.

[0055] In other embodiments, the diameter of the burn-in hole D2 may be less than 0.05 mm larger than the diameter of the window opening D1. For example, the diameter of the burn-in hole D2 may be 0.04 mm larger than the diameter of the window opening D1, or the diameter of the burn-in hole D2 may be 0.045 mm larger than the diameter of the window opening D1, etc.

[0056] In other embodiments, the diameter of the burn-in hole D2 may be more than 0.1 mm larger than the diameter of the window opening D1. For example, the diameter of the burn-in hole D2 may be 0.105 mm larger than the diameter of the window opening D1, or the diameter of the burn-in hole D2 may be 0.11 mm larger than the diameter of the window opening D1, etc.

[0057] In some embodiments, the circular cut diameter D3 is 0.01mm-0.02mm smaller than the window opening diameter D1, and the circular cut diameter D3 is 0.01mm-0.02mm larger than the wire-wound diameter D2. This is beneficial for trimming the residual glass fibers at the opening and on the wall, avoiding direct expansion to the outside of the window, and reducing the risk of damaging the inner copper layer 13 and causing the aperture to exceed tolerance by adjusting the parameters.

[0058] In other embodiments, when the circular cut diameter D3 is 0.01mm-0.02mm smaller than the window opening diameter D1, the circular cut diameter D3 can be less than 0.01mm larger than the firing diameter D2. For example, the circular cut diameter D3 can be 0.009mm larger than the firing diameter D2, or the circular cut diameter D3 can be 0.008mm larger than the firing diameter D2. Of course, the circular cut diameter D3 can also be more than 0.02mm larger than the firing diameter D2. For example, the circular cut diameter D3 can be 0.021mm larger than the firing diameter D2, or the circular cut diameter D3 can be 0.022mm larger than the firing diameter D2.

[0059] In other embodiments, when the circular cut diameter D3 is 0.01mm-0.02mm larger than the sintering diameter D2, the circular cut diameter D3 can be less than 0.01mm smaller than the windowed diameter D1. For example, the circular cut diameter D3 can be 0.009mm smaller than the windowed diameter D1, or the circular cut diameter D3 can be 0.008mm smaller than the windowed diameter D1. Of course, the circular cut diameter D3 can also be more than 0.02mm smaller than the windowed diameter D1. For example, the circular cut diameter D3 can be 0.021mm smaller than the windowed diameter D1, or the circular cut diameter D3 can be 0.022mm smaller than the windowed diameter D1.

[0060] Please refer to Figure 8 In some embodiments, during the borehole enlargement process, the coverage area S1 of the laser aperture is 0.011 mm. 2 -0.020mm 2 .

[0061] Understandably, the coverage area S1 of the laser aperture can be 0.011 mm. 2 0.012mm 2 0.013mm 2 0.014mm 2 0.015mm 2 0.016mm 2 0.017mm 2 0.018mm 2 0.019mm 2 or 0.020mm 2 wait.

[0062] Compared to related technologies where the laser aperture coverage area S2 is 0.020mm 2 -0.031mm 2 By reducing the laser aperture, energy can be more concentrated and the heat diffusion range can be smaller, making the treatment of glass fibers more effective. In addition, the smaller laser aperture, combined with the burning path, can improve the uniformity of the repair of glass fiber residue on the hole wall and reduce the risk of excessive enlargement of the hole size.

[0063] In other embodiments, the coverage area S1 of the laser aperture can be 0.010 mm. 2 0.009mm 2 0.008mm 2 0.007mm 2 0.006mm 2 or 0.005mm 2 Of course, if the roughness of the hole wall can be improved after circular cutting, the coverage area S1 of the laser aperture can also be designed to be 0.020mm. 2 -0.031mm 2 For example, the coverage area S1 of the laser aperture can be 0.020 mm. 2 0.021mm 2 0.022mm 2 0.023mm 2 0.024mm 2 0.025mm 2 0.026mm 2 0.027mm 2 0.028mm 2 0.029mm 2 0.030mm 2 or 0.031mm 2 wait.

[0064] In some embodiments, when using laser cold processing for circular cutting, the depth of the damage to the inner copper layer 13 of the substrate 10 to be drilled is less than 0.005 mm, so as to avoid causing a significant impact on the inner copper layer 13.

[0065] The laser drilling method of the circuit board manufacturing method of this application is carried out in steps by winding and burning and circular cutting, which solves the problem of rough hole walls that are easy to be generated in deep micro blind holes 14. The specific process includes: substrate to be drilled → window opening → hole shrinking winding and burning → circular cutting → post-processing.

[0066] Windowing: Windowing refers to removing the copper layer at the orifice. This can be achieved through etching, where a dry film / wet film is applied to the outer copper layer 11 of the substrate 10 with the drilled hole. After exposure and development, the copper layer at the orifice not covered by the dry / wet film is etched away. Alternatively, mechanical windowing can be used, such as laser or mechanical controlled-depth drilling, to remove the copper layer at the orifice. The window size D1 is equal to the final hole diameter.

[0067] Enlarging via laser winding: The enlarging aperture D2 is smaller than the finished aperture, i.e., the enlarging aperture D2 is smaller than the window aperture D1. Specifically, when creating CO2 laser enlarging data, the enlarging aperture D2 is reduced by 0.05mm relative to the window aperture D1. For large holes with an upper aperture greater than 0.35mm, the reduction can be set to 0.06mm-0.08mm. During operation, the premise should be that the inner copper layer 13 has no floating or padding, and the aperture meets the design requirements. Adjust the pulse number, energy, and enlarging path to ensure that the prepreg is fully removed and the exposed glass fiber on the hole wall is reduced. Even if more resin is ablated during enlarging via laser winding, and the glass fiber on the hole wall is not completely removed, this problem can still be solved because a circular cutting step is designed in the subsequent process. Among them, using a CO2 laser for enlarging via laser winding can balance processing efficiency and production cost.

[0068] When using a carbon dioxide laser device with adjustable aperture for sintering, compared to existing laser processing parameters, this application lowers the laser aperture; the conventionally set laser aperture can cover an area of ​​0.020mm. 2 -0.031mm 2 This application reduces the coverage area of ​​the laser aperture to 0.011mm. 2 -0.020mm 2 The advantage lies in the fact that the energy of the small aperture is more concentrated and the heat diffusion range is smaller, which is more effective for the treatment of glass fibers. In addition, the small aperture combined with the burning path can improve the uniformity of the repair of glass fiber residue on the hole wall and reduce the risk of excessive enlargement of the hole size.

[0069] Circular Cutting: After the winding and burning process is completed, a UV laser is used for circular cutting. The circular cut diameter D3 should be 0.01mm-0.02mm smaller than the window opening diameter D1, and 0.01mm-0.02mm larger than the winding and burning diameter D2. Simultaneously, the depth of damage to the inner copper layer 13 should be controlled within 0.005mm. The advantage of this dimensional setting is that it places the circular cut boundary between the window opening boundary and the winding and burning boundary, allowing for directional trimming of the hole opening and residual glass fiber on the hole wall, preventing direct expansion to the outside of the window opening. At the same time, adjusting the parameters reduces the risk of damaging the inner copper layer 13 and causing out-of-tolerance hole diameter. In practice, a single-point routing method can be used for circular cutting. The single-point routing method needs to be designed in the engineering data, and then the machine's single-point processing method is used to complete one loop. Circular cutting can also be performed using a nested circular method, where the laser beam continuously travels multiple circles. As the laser moves in circles, the focal point moves downwards layer by layer along the material depth direction. Alternatively, a ring-shaped laser beam can be used, and circular cutting is achieved through the rotation of the ring-shaped laser beam. In terms of parameter control, position compensation is performed based on expansion and contraction data before circular cutting. A gentle ultraviolet laser process with low pulse energy, multiple laser beams, and multiple revolutions is used. After the first piece is completed, a cross-section inspection is performed to confirm the hole diameter, hole wall roughness, and the depth of damage to the inner copper layer 13. Only after meeting the requirements can mass production begin.

[0070] By optimizing the process design, using carbon dioxide laser drilling followed by ultraviolet circular cutting, and adjusting the drill strip data, the roughness of the hole wall during the deep micro blind hole 14 machining process was improved, thereby reducing abnormal scrap such as crab legs and plating defects caused by the roughness of the hole wall.

[0071] The second aspect of this application discloses a circuit board manufactured by the circuit board manufacturing method described in the first aspect.

[0072] The circuit board adopts any one or more embodiments of the circuit board manufacturing method described above, and therefore has the beneficial effects of the embodiments described above, which will not be repeated here.

[0073] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for manufacturing a circuit board, characterized in that, include: A substrate to be drilled is provided, and a window is made in the outer copper layer of the substrate to be drilled to remove the copper layer at the hole opening, and the diameter of the window opening is equal to the diameter of the finished hole. The hole is enlarged by laser thermal processing, and the diameter of the enlarged hole is smaller than the diameter of the window opening. Laser cold processing is used to perform circular cutting to obtain deep micro blind holes. The diameter of the circularly cut hole is smaller than the diameter of the window opening and larger than the diameter of the burn-through hole.

2. The circuit board manufacturing method as described in claim 1, characterized in that, Hole enlargement using laser thermal processing includes: hole enlargement using carbon dioxide laser; and / or circular cutting using laser cold processing includes: circular cutting using ultraviolet laser.

3. The circuit board manufacturing method as described in claim 1 or 2, characterized in that, The diameter of the burn-in hole is 0.05mm-0.1mm smaller than the diameter of the window opening.

4. The circuit board manufacturing method as described in claim 1 or 2, characterized in that, The diameter of the circular cut hole is 0.01mm-0.02mm smaller than the diameter of the window opening, and the diameter of the circular cut hole is 0.01mm-0.02mm larger than the diameter of the burnishing hole.

5. The circuit board manufacturing method as described in claim 1 or 2, characterized in that, During the borehole enlargement process, the coverage area of ​​the laser aperture is 0.011mm. 2 -0.020mm 2 .

6. The circuit board manufacturing method as described in claim 1 or 2, characterized in that, Circular cutting using laser cold processing involves drilling a hole at one point with the laser beam, then moving to the next point, and completing a full circle of the laser beam to achieve circular cutting.

7. The circuit board manufacturing method as described in claim 1 or 2, characterized in that, Circular cutting using laser cold processing includes: The laser beam travels in multiple circles continuously. As the laser beam moves in circles, the focal point moves downwards layer by layer along the depth direction of the material to achieve circular cutting; or, The laser beam is a ring laser beam, and circular cutting is achieved by rotating the ring laser beam.

8. The circuit board manufacturing method as described in claim 1 or 2, characterized in that, When using laser cold processing for circular cutting, the depth of the inner copper layer of the substrate to be drilled is less than 0.0005 mm.

9. The circuit board manufacturing method as described in claim 1 or 2, characterized in that, The outer copper layer of the substrate to be drilled is opened by etching; or, the outer copper layer of the substrate to be drilled is opened by machining.

10. A circuit board, characterized in that, Includes circuit boards manufactured by any one of claims 1-9.

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