Fine line PCB and method of manufacturing the same

Abstract

This invention discloses a PCB board with fine lines and its preparation method, relating to the field of PCB processing. The preparation method includes preparing a copper-clad laminate with a hydrocarbon resin substrate; using a UV laser with a wavelength of 315-400 nm to etch away copper foil to form circuit patterns; using a CO2 or green laser to remove the substrate to process holes; and cleaning, wet desmearing, shadowing, dry lamination, and electroplating the copper-clad laminate to obtain the PCB board. This application uses a UV laser to remove the copper foil on the surface of the copper-clad laminate to process circuit patterns without damaging the substrate, and utilizes a CO2 or green laser to remove the substrate to process holes. This enables ultra-fine circuit processing with a line width / spacing ≤15 μm, and the high etching factor and uniformity result in low resistance and heat loss. This method requires no chemically polluting reagents and does not use special materials, improving processing efficiency and quality while reducing production costs and environmental impact.

Description

Technical Field

[0001] This invention relates to the field of circuit board processing, and more particularly to a PCB board with fine circuitry and its preparation method. Background Technology

[0002] With the rapid development of 5G communication, artificial intelligence, high-speed computing and other fields, higher requirements are placed on the signal integrity, transmission loss, wiring density and dimensional accuracy of printed circuit boards (PCBs). High-frequency PCBs need to use substrates with low dielectric constant (Dk) and low loss factor (Df), such as hydrocarbon resin and polytetrafluoroethylene, and achieve high-reliability manufacturing of micro-line (line width / line spacing ≤20 μm) and high-precision interconnect holes.

[0003] Currently, the mainstream circuit forming processes in the industry can be mainly divided into three categories: subtractive, semi-additive, and additive. The subtractive process includes drilling, electroplating, film lamination, exposure, development, and etching. Its achievable precision is generally ≥30 μm. Its limitation lies in its reliance on chemical etching, which consumes a large amount of chemicals, generating significant wastewater and exhaust gas, leading to substantial environmental pressure. Furthermore, the side etching phenomenon limits circuit precision, making it difficult to stably manufacture circuits ≤20 μm. The semi-additive process includes ultra-thin copper foil, drilling, patterned electroplating, and flash etching, achieving a precision of 10-15 μm. However, its limitation is its reliance on ultra-thin copper foil, resulting in high material costs and limited supply. The additive process includes drilling of the insulating substrate, catalysis, electroless copper plating, patterned resist plating, and electroplating thickening, achieving a precision below 10 μm. Its limitations include the need for specialized catalyst layers or photoconductive materials, resulting in a narrow material selection. Moreover, electroless copper plating is slow, leading to low production efficiency, and its coating adhesion and reliability are often lower than traditional lamination methods.

[0004] In summary, the current circuit forming process in the industry involves many wet chemical processes, which leads to increasingly higher costs for pollutant treatment. Moreover, due to limitations in physical or chemical processing principles, it is difficult to meet the requirements of high precision and high reliability. Some processes also require the use of special materials and high-precision equipment, which further increases manufacturing costs. Summary of the Invention

[0005] This invention provides a PCB board with fine circuitry and its preparation method. By using a UV laser to etch and remove the copper foil from a copper-clad laminate with a carbonate resin dielectric, circuit patterns and hole structures can be processed. Laser forming can be achieved in one step, the process is simple, and there is no need to use expensive special materials or generate chemical reagents, which improves environmental protection and reduces production costs.

[0006] To address the aforementioned technical problems, one objective of this invention is to provide a method for fabricating a PCB board with fine-lined circuitry, comprising the following steps: (1) Prepare a copper-clad laminate, the copper-clad laminate comprising a substrate and copper foil on both sides of the substrate, the substrate comprising a hydrocarbon resin; (2) Use a UV laser with a wavelength of 315-400 nm to etch away the copper foil on the surface of the copper-clad laminate to form a circuit pattern. Switch or use a CO2 laser or a green laser simultaneously to ablate the substrate at the location where blind holes or through holes need to be formed on the copper-clad laminate to form blind holes or through holes. (3) After cleaning, wet desmearing, shadow removal, dry lamination and electroplating of the copper-clad laminate, a PCB board is prepared.

[0007] This application utilizes the near-zero absorption optical properties of hydrocarbon resins to UV lasers with wavelengths of 315-400 nm, transforming the UV laser into a high-precision, heat-damage-free selective copper stripping tool. This allows the UV laser to precisely remove only the copper foil on the surface of the copper-clad laminate, without damaging the substrate layer, thus improving product reliability. Subsequently, CO2 or green lasers are used to remove the substrate for hole processing. This method combines the traditionally separate circuit fabrication and drilling processes into a single step, eliminating errors caused by multiple positioning steps, avoiding hole / line misalignment, and improving processing accuracy. It can achieve ultra-fine circuit processing with line width / spacing ≤15 μm, and the line etching factor is improved, resulting in larger conductor cross-sectional area and longer conductor perimeter, reducing current concentration problems caused by the skin effect, effectively reducing resistance and heat loss, and improving overall circuit uniformity. This application uses a dry physical processing method throughout, eliminating the need for any chemical etching solutions or expensive special materials, thus avoiding chemical pollution and improving processing efficiency and quality while reducing production costs.

[0008] In some embodiments, in step (1), the thickness of the copper foil is 3-35 μm.

[0009] In some embodiments, in step (1), the thickness of the copper foil is any one or a range between any two of 3 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, and 35 μm.

[0010] In some embodiments, in step (1), the substrate thickness of the copper-clad laminate is 50-300 μm.

[0011] In some embodiments, in step (1), the substrate thickness of the copper-clad laminate is 168-254 μm.

[0012] In some embodiments, in step (1), the thickness of the copper foil is 12-35 μm.

[0013] The thickness of the copper foil in the copper-clad laminate of this application is controlled within the above-mentioned preferred range, which can avoid excessive copper foil thickness, thereby improving the etching factor and reducing substrate damage. If the copper foil thickness is too large, it will cause the circuit to appear trapezoidal, resulting in poor linearity and a decrease in the etching factor. Secondly, excessive copper foil thickness will also accelerate the loss of laser life. Excessive laser accumulation may lead to heat accumulation, resulting in the risk of substrate melting and making the substrate surface prone to damage.

[0014] In some embodiments, in step (2), the UV laser has a pulse width of 10-1000 ns, a pulse frequency of 40-300 kHz, a power of 2-20 W, and a scanning speed of 100-1000 mm / s.

[0015] In some embodiments, in step (2), the UV laser has a pulse width of 50-100 ns, a pulse frequency of 40-60 kHz, a power of 2-8 W, and a scanning speed of 400-600 mm / s.

[0016] The UV laser parameters of this application are preferably within the above-mentioned range. The UV laser pulse width is selected in the range of 50-100 ns to avoid damage to the substrate due to nonlinear absorption. In addition, in order to ensure the ablation capability of the laser on the copper foil, the pulse frequency is controlled in the range of 40-60 kHz, because a higher frequency will lead to a decrease in the peak power of the laser. Similarly, the laser scanning speed is controlled in the range of 400-600 mm / s to avoid the risk of incomplete ablation of the copper foil due to excessive speed, which would reduce the etching factor.

[0017] In some implementations, in step (2), the minimum line width and line spacing of the circuit pattern are independent and are 12-50 μm, and the minimum diameter of the blind via is 20-180 μm.

[0018] This application utilizes the transparent absorption characteristics of hydrocarbon resin in the UV laser band, enabling UV laser to precisely etch and remove copper foil. By eliminating the traditional separate circuit fabrication and drilling processes, errors caused by multiple positioning can be avoided. Furthermore, the circuit etching factor is high and the heat loss is low, allowing for stable manufacturing of circuits ≤15 μm, thus improving the processing accuracy of PCB boards.

[0019] In some embodiments, in step (2), the wavelength of the CO2 laser is 9300-10600 nm.

[0020] In some embodiments, the wavelength of the green laser is 515-543 nm.

[0021] In some embodiments, in step (2), the pulse width of the CO2 laser is 1-30 μs, the single pulse energy is 2-30 mj, the number of single-hole impacts is 1-5 shots, and the pulse frequency is 1-15 kHz.

[0022] In some embodiments, in step (2), the pulse width of the green laser is 1-15 ps, the pulse frequency is 50 kHz-5 MHz, the power is 10-150 W, and the scanning speed is 500-8000 mm / s.

[0023] This application uses CO2 or green laser to burn off the substrate on the copper-clad laminate. The laser utilizes the high absorption rate of hydrocarbon resin at this wavelength to achieve efficient vaporization and drilling of the material. The process is simple and produces no polluting reagents, which can improve processing efficiency and processing quality.

[0024] In some embodiments, in step (1), the substrate is Rogers RO4350B laminate.

[0025] In some embodiments, in step (1), the copper foil is low profile electrolytic copper foil (LoPro), reverse copper foil (RTC), or standard electrolytic copper foil (ED).

[0026] To address the aforementioned technical problems, the second objective of this invention is to provide a PCB board with fine-lined circuitry.

[0027] Compared with the prior art, the present invention has the following beneficial effects: 1. This application utilizes the near-zero absorption optical properties of hydrocarbon resin to UV lasers with wavelengths of 315-400 nm to precisely remove copper foil from the surface of copper-clad laminates without damaging the substrate layer. CO2 or green lasers are then used to remove the substrate to process holes. The circuit fabrication and drilling processes can be performed in the same process, eliminating errors caused by multiple positioning. This enables ultra-fine circuit processing with line width / spacing ≤15 μm, and the high etching factor effectively reduces resistance and heat loss, improving the overall uniformity of the circuit.

[0028] 2. The entire process of precision circuit processing of the PCB board in this application is a dry physical processing method, which does not require the use of any chemical etching solution or any expensive special materials. It does not generate chemical pollution reagents, reduces environmental pressure, and improves processing efficiency and quality, resulting in low production costs. Attached Figure Description

[0029] Figure 1 This is a schematic diagram showing the damage to the substrate after processing of the copper-clad laminate in Embodiment 1 and Comparative Example 2 of the present invention (left: Comparative Example 2; right: Embodiment 1). Figure 2The test results of the line etching factor of a PCB board with fine lines in Embodiment 1 of the present invention; Figure 3 The test results of the line etching factor of a PCB board with fine lines in Comparative Example 1 of the present invention. Figure 4 The test results of the line etching factor of a PCB board with fine lines in Comparative Example 2 of the present invention. Figure 5 The test results of the line etching factor of a PCB board with fine lines in Comparative Example 3 of the present invention. Figure 6 The insertion loss test results are for a PCB board with fine lines in Embodiment 2 of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicating orientation or positional relationship are 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, and therefore should not be construed as a limitation of this invention.

[0034] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the following embodiments and comparative examples are all commercially available, and the same raw materials were used in parallel experiments.

[0035] Example 1 A method for fabricating a PCB board with fine lines includes the following steps: (1) Select a high-frequency copper clad laminate with a hydrocarbon resin substrate. The copper clad laminate includes a substrate (core) and copper foil on both sides of the substrate. In this embodiment, the substrate is Rogers RO4350B laminate and the copper foil is LoPro copper foil. The thickness of the substrate in the copper clad laminate is 254 μm and the thickness of the copper foil is 18 μm. (2) Import the circuit pattern and hole position data into a dual-source laser processing system equipped with a UV laser and a CO2 RF laser. The minimum line width and line spacing are designed to be 30 μm, and the minimum blind hole diameter is 150 μm. The copper foil on the surface of the copper-clad board is removed by UV laser etching with a wavelength of 355 nm, a pulse width of 80 ns, a pulse frequency of 40 kHz, a power of 2.5 W, and a scanning speed of 500 mm / s to form the circuit pattern. (3) At the location where blind vias need to be formed on the copper-clad laminate, a CO2 laser with a wavelength of 10600 nm is used to ablate the substrate. The single pulse energy is 20 mj, the pulse width is 10 μs, the number of single-hole impacts is 4 shots, the pulse frequency is 3kHz, and a single-spot processing method (Punch) is used to form blind vias. (4) The holes of the processed copper-clad board are subjected to plasma cleaning, wet adhesive removal, and black shadow treatment to deposit conductive graphite colloid on the surface of the blind holes. Then, dry lamination and electroplating are performed to fill the holes and prepare the PCB board.

[0036] Example 2 A method for fabricating a PCB board with fine lines includes the following steps: (1) Select a high-frequency copper clad laminate with a hydrocarbon resin substrate. The copper clad laminate includes a substrate (core) and copper foil on both sides of the substrate. In this embodiment, the substrate is Rogers RO4350B laminate containing hydrocarbon resin, and the copper foil is LoPro copper foil. The thickness of the substrate of the copper clad laminate is 168 μm and the thickness of the copper foil is 18 μm. (2) Import the circuit pattern and hole position data into a dual-source laser processing system equipped with a UV laser and a CO2 RF laser. The minimum line width and line spacing are designed to be 12 μm, and the minimum blind hole diameter is 120 μm. The copper foil on the surface of the copper-clad board is removed by UV laser etching with a wavelength of 355 nm. The pulse width is 15 ns, the pulse frequency is 40 kHz, the power is 2.2 W, and the scanning speed is 450 mm / s to form the circuit pattern. (3) At the location where blind vias need to be formed on the copper-clad laminate, a CO2 laser with a wavelength of 10600 nm is used to ablate the substrate. The single pulse energy is 16 mj, the pulse width is 8 μs, the number of single-hole impacts is 3 shots, the pulse frequency is 3 kHz, and the single-spot processing method (Punch) is used to form blind vias. (4) The holes of the processed copper-clad board are subjected to plasma cleaning, wet adhesive removal, and black shadow treatment to deposit conductive graphite colloid on the surface of the blind holes. Then, dry lamination and electroplating are performed to fill the holes and prepare the PCB board.

[0037] Example 3 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 1. The difference is that in step (2), the minimum line width and line spacing are designed to be 12 μm and the minimum blind hole diameter is 120 μm.

[0038] Example 4 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3, except that in step (2), the wavelength of the UV laser is 315 nm.

[0039] Example 5 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3, except that in step (2), the wavelength of the UV laser is 400 nm.

[0040] Example 6 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3. The difference is that in step (2), the UV laser etching pulse width is 50 ns, the pulse frequency is 60 kHz, the power is 8 W, and the scanning speed is 400 mm / s to form a circuit pattern.

[0041] Example 7 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3. The difference is that in step (2), the pulse width of the UV laser etching is 100 ns, the pulse frequency is 50 kHz, the power is 3 W, and the scanning speed is 600 mm / s.

[0042] Example 8 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3. The difference is that in step (2), the pulse width of the UV laser etching is 30 ns, the pulse frequency is 100 kHz, the power is 2 W, and the scanning speed is 800 mm / s.

[0043] Example 9 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3, except that the copper foil thickness is 35 μm in step (1).

[0044] Example 10 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3, except that the copper foil thickness is 25 μm in step (1).

[0045] Example 11 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3, except that the copper foil thickness is 12 μm in step (1).

[0046] Example 12 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 3. The difference is that in step (3), at the position where blind holes need to be formed on the copper-clad board, a green laser with a wavelength of 532 nm is used to ablate and form the substrate, with a pulse width of 15 ps, a pulse frequency of 500 kHz, a power of 30 W and a scanning speed of 500 mm / s.

[0047] Comparative Example 1 A method for fabricating a PCB board with fine lines includes the following steps: (1) Select a high-frequency copper-clad laminate with a hydrocarbon resin substrate. The copper-clad laminate includes a substrate and copper foil on both sides of the substrate. In this embodiment, the substrate is Rogers RO4350B laminate, the copper foil is LoPro copper foil, the thickness of the copper-clad laminate is 254 μm, the thickness of the copper foil is 18 μm, the minimum line width and line spacing are designed to be 30 μm, and the minimum blind hole diameter is 150 μm. (2) A 30 μm dry film is wet-laid on the copper foil surface of the copper-clad laminate, and exposed with 405 nm UV light to transfer the circuit pattern to the dry film. After standing, it is developed and etched to open windows to remove the copper foil and form the circuit pattern. (3) At the location where through holes or blind holes need to be formed on the copper-clad laminate, switch to using a CO2 laser with a wavelength of 10600 nm to ablate and form the substrate. The single pulse energy is 20 mj, the pulse width is 10 μs, the number of single hole impacts is 4 shots, the pulse frequency is 3 kHz, and the single spot processing method (Punch) is used to form blind holes. (4) The holes of the processed copper-clad board are subjected to plasma cleaning, wet adhesive removal, and black shadow treatment to deposit conductive graphite colloid on the surface of the blind holes. Then, dry lamination and electroplating are performed to fill the holes and prepare the PCB board.

[0048] Comparative Example 2 A method for preparing a fine-line PCB board, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 1. The difference is that in step (1), the substrate of the copper-clad laminate is a multifunctional epoxy resin, specifically EM-526 of the EMC brand, with a substrate thickness of 254 μm, and the copper foil is reverse-processed copper foil (RTF) with a copper foil thickness of 18 μm.

[0049] Comparative Example 3 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 1. The difference is that in step (1), the substrate of the copper clad laminate is polyimide (PI) with a thickness of 254 μm, and the copper foil is reverse-treated copper foil (RTF) with a thickness of 18 μm.

[0050] Comparative Example 4 A method for preparing a PCB board with fine lines, wherein each step of the preparation method and the raw materials, equipment and process parameters used in each step are the same as those in Example 1. The difference is that in step (2), the circuit pattern and hole position data are imported into a dual-source laser processing system equipped with a green laser and a CO2 radio frequency laser. The minimum line width and line spacing are designed to be 30 μm, the minimum blind hole diameter is 150 μm, and a 532 nm green laser is used to etch and remove the copper foil on the surface of the copper-clad board. The pulse width is 100 ps, ​​the pulse frequency is 1000 kHz, the power is 15 W, and the scanning speed is 1000 mm / s to form the circuit pattern.

[0051] Performance testing 1. Line dimensions and hole position accuracy: Line dimensions were measured using a high-precision line width measuring instrument, and hole position accuracy was measured using a Hole AOI (automatic hole inspection machine). The test results are shown in Table 1 below.

[0052] 2. Etching Factor: After fabricating the circuit in step (2) of the examples and comparative examples, the ratio of the top and bottom line widths to the copper foil thickness is measured. The formula is S=2H / (W1-W2), where S is the etching factor, H is the copper foil thickness, W1 is the bottom line width, and W2 is the top line width. The calculated etching factors are shown in Table 1 below. Figure 2-5 As shown.

[0053] 3. Insertion Loss: The insertion loss at 28 GHz was tested according to the IPC-TM-650 2.5.5.12 standard. Insertion loss refers to the energy loss of the signal after passing through the component. Generally, the loss value per unit length is compared. The test results are shown in Table 1 below. Figure 6 As shown.

[0054] 4. Substrate layer condition: After the copper foil of the copper-clad laminates of the examples and comparative examples is removed by UV laser in step (2), the copper-clad laminates are sliced ​​and the substrate cross-section at the location of the laser-etched copper foil is observed to be flush with the original substrate cross-section before laser etching. If the substrate depression depth is basically 0, it is defined as intact; if the substrate depression depth is ≤10 μm, it is defined as slightly damaged; if the substrate depression depth is >10 μm, it is defined as damaged. The observation results are shown in Table 1 below.

[0055] Table 1 - Etching effect of blind vias on PCB boards in embodiments and comparative examples of this application. In Examples 1-12 of this application, the near-zero absorption optical property of hydrocarbon resin to UV lasers with wavelengths of 300-400 nm is utilized to precisely remove copper foil from the surface of copper-clad laminates using UV lasers without damaging the hydrocarbon resin substrate layer, thus improving product reliability. Furthermore, the high absorption rate of hydrocarbon resin to CO2 or green light of this specific wavelength enables efficient vaporization drilling of the material, improving processing accuracy. This allows for ultra-fine circuit processing with linewidth / spacing as low as 12 μm, and the line etching factor is improved, reducing the current concentration problem caused by the skin effect and effectively reducing resistance and heat loss.

[0056] A comparison of the schemes in Examples 1 and 3 shows that in Example 1, the minimum linewidth and line spacing of the copper foil circuit pattern are 30 μm, and the minimum blind via diameter is 150 μm. In Example 3, the minimum linewidth and line spacing of the copper foil circuit pattern are 12 μm, and the minimum blind via diameter is 120 μm. It can be observed that, under the premise of copper foil of the same thickness, the smaller the linewidth and line spacing, the lower the etching factor, indicating that the smaller the circuit size, the more difficult it is to improve the processing accuracy. This application can achieve ultra-fine circuit processing with a linewidth / line spacing ≤ 15 μm, and the processed circuit has a high etching factor and good linearity.

[0057] Compared to Example 1, Comparative Example 1 uses a traditional wet chemical method to etch the copper foil of the copper-clad laminate. The circuit fabrication and drilling are carried out in different processes, requiring multiple positioning, resulting in larger errors and lower processing accuracy. The circuit size and hole position tolerances are larger, the etching factor of the processed circuit is lower, the cross-sectional area of ​​the conductor is increased, and the resistance and heat loss are higher.

[0058] Compared to Example 1, the copper-clad laminate in Comparative Example 2 uses a multifunctional epoxy resin substrate, while the copper-clad laminate in Comparative Example 3 uses a polyimide substrate. Figure 1 As shown, due to the high absorption characteristics of multifunctional epoxy resin and polyimide for the 355nm wavelength UV laser, during the UV laser removal of copper foil etched circuits, part of the substrate will be burned off simultaneously, causing damage to the substrate. The unevenness of the substrate interface may lead to substrate cracking or the entry of foreign matter into the substrate, resulting in unqualified products and reduced reliability.

[0059] Compared to Example 1, Comparative Example 4 uses a green laser with a wavelength of 532 nm to etch the copper foil on the surface of the copper-clad laminate to process circuit patterns. However, due to the high absorption rate of the hydrocarbon resin of this wavelength green laser, the copper foil etching process will simultaneously damage the hydrocarbon resin substrate, resulting in unqualified products and reduced reliability.

[0060] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for fabricating a PCB board with fine circuitry, characterized in that, Includes the following steps: (1) Prepare a copper-clad laminate, the copper-clad laminate comprising a substrate and copper foil on both sides of the substrate, the substrate comprising a hydrocarbon resin; (2) Use a UV laser with a wavelength of 315-400 nm to etch away the copper foil on the surface of the copper-clad laminate to form a circuit pattern. Switch or use a CO2 laser or a green laser simultaneously to ablate the substrate at the location where blind holes or through holes need to be formed on the copper-clad laminate to form blind holes or through holes. (3) After cleaning, wet desmearing, shadow removal, dry lamination and electroplating of the copper-clad laminate, a PCB board is prepared.

2. The method for preparing a PCB board with fine circuitry as described in claim 1, characterized in that, In step (1), the thickness of the copper foil is 3-35 μm; And / or, in step (1), the substrate thickness of the copper-clad laminate is 50-300 μm.

3. The method for preparing a PCB board with fine lines as described in claim 2, characterized in that, In step (1), the thickness of the copper foil is 12-35 μm; And / or, in step (1), the substrate thickness of the copper-clad laminate is 168-254 μm.

4. The method for preparing a PCB board with fine circuitry as described in claim 1, characterized in that, In step (2), the UV laser has a pulse width of 10-1000 ns, a pulse frequency of 40-300 kHz, a power of 2-20 W, and a scanning speed of 100-1000 mm / s.

5. The method for preparing a PCB board with fine lines as described in claim 4, characterized in that, In step (2), the UV laser has a pulse width of 50-100 ns, a pulse frequency of 40-60 kHz, a power of 2-8 W, and a scanning speed of 400-600 mm / s.

6. The method for preparing a PCB board with fine lines as described in claim 1, characterized in that, In step (2), the minimum line width and line spacing of the circuit pattern are independent and range from 12 to 50 μm, and the minimum diameter of the blind hole is 20 to 180 μm.

7. The method for preparing a PCB board with fine lines as described in claim 1, characterized in that, In step (2), the wavelength of the CO2 laser is 9300-10600 nm; And / or, the wavelength of the green laser is 515-543 nm.

8. The method for preparing a PCB board with fine lines as described in claim 5, characterized in that, In step (2), the pulse width of the CO2 laser is 1-30 μs, the single pulse energy is 2-30 mj, the number of single-hole impacts is 1-5 shots, and the pulse frequency is 1-15 kHz.

9. The method for preparing a PCB board with fine lines as described in claim 5, characterized in that, In step (2), the green laser has a pulse width of 1-15 ps, a pulse frequency of 50 kHz-5 MHz, a power of 10-150 W, and a scanning speed of 500-8000 mm / s.

10. A PCB board with fine lines prepared by the method described in any one of claims 1-9.

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