Flexible circuit board, via hole redundant structure and manufacturing method thereof, and electronic equipment

Abstract

The invention discloses a flexible circuit board, a via hole redundant structure of the flexible circuit board, a manufacturing method of the via hole redundant structure and electronic equipment, and is used for electrically connecting a first conductive layer and a second conductive layer of the flexible circuit board. The plurality of micro-conduction holes are arranged according to a preset pattern in a corresponding electrical connection area of the first conductive layer and the second conductive layer, and the aperture of each micro-conduction hole is equal and ranges from 0.01 mm to 0.05 mm. A traditional single via hole is replaced by a plurality of micro via hole arrays arranged according to a preset pattern, so that the problem of circuit reliability reduction caused by single-point failure due to the fact that semi-flowing colloid flows into the via holes in the production and manufacturing process is fundamentally solved, the product yield is remarkably increased, and the service life of the product is remarkably prolonged.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit board printing technology, specifically to a flexible circuit board and its redundant via structure and manufacturing method, and electronic devices. Background Technology

[0002] Flexible circuit boards (PCBs) have become core components in consumer electronics, medical devices, and other fields due to their advantages such as flexibility and thinness. In multilayer flexible PCBs, vias are key structures for achieving electrical connections between different conductive layers. Currently, the industry commonly uses mechanical drilling to form individual vias.

[0003] However, this traditional single-hole connection method has inherent reliability risks. First, the diameter of mechanically drilled holes is limited by the physical size of the drill bit, with a lower limit of approximately 0.05mm, making it difficult to meet the requirements of high-density interconnects. More importantly, in subsequent assembly processes, a cover film needs to be laminated onto the board surface to protect the circuitry. During this high-pressure, high-temperature process, the semi-fluid colloid of the cover film can easily flow into the via, causing partial or complete blockage of the via walls. This degrades the effectiveness of subsequent via metallization (such as chemical copper plating), leading to increased via resistance or, in severe cases, open circuits between layers, seriously affecting the electrical performance and long-term reliability of the product. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a flexible circuit board and its redundant via structure and manufacturing method, as well as an electronic device. The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a redundant via structure for a flexible circuit board, used for electrically connecting a first conductive layer and a second conductive layer of a flexible circuit board. The redundant via structure is composed of a plurality of independent micro vias, which are arranged in a preset pattern in the corresponding electrical connection areas of the first conductive layer and the second conductive layer. Each micro via has the same aperture, and the aperture ranges from 0.01 mm to 0.05 mm.

[0005] The beneficial effects of this invention are as follows: by replacing the traditional single via with an array of multiple micro-vias arranged in a preset pattern, a parallel redundancy is created in the structure. Therefore, during the manufacturing process, when one or more micro-vias are blocked or covered by subsequent processes (such as cover film lamination), the remaining micro-vias can still effectively maintain the interlayer electrical connection of multiple conductive layers. This fundamentally solves the problem of single-point failure caused by semi-fluid colloid flowing into the vias during manufacturing, leading to reduced circuit reliability and significantly improving product yield and service life.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the plurality of micro-vias are arranged in a cross shape.

[0008] The beneficial effect of adopting the above-mentioned further solution is that by arranging multiple micro-vias in a cross shape, the arrangement of multiple micro-vias in this invention provides a uniform and symmetrical hole distribution on the plane, thereby optimally dispersing process stresses (such as cover film pressure) from various directions, and making the conductive path more uniform and stable on the two-dimensional plane, further optimizing the reliability of redundant connections.

[0009] Furthermore, the cross-shaped arrangement includes a central micro-via and four micro-vias arranged around the central micro-via in four mutually perpendicular directions, together forming an array of five micro-vias.

[0010] The beneficial effect of adopting the above-described further solution is that by employing a centrally arranged cross-shaped array of five holes, the present invention achieves a specific structure that balances optimal redundancy and space efficiency. The layout of the central hole and the four directional holes maximizes the utilization of the connection area, ensuring that multiple effective pathways remain even in extreme cases.

[0011] Furthermore, the micro-through hole is a blind hole or through hole formed by laser processing.

[0012] The beneficial effects of adopting the above-mentioned further solution are: by using laser equipment to process the flexible circuit board to form micro-vias, the feasibility of small aperture and precise arrangement structure is ensured. At the same time, the laser processing method used in this invention, compared with the traditional mechanical drilling method, can reduce the heat-affected zone of the flexible circuit board during the processing of micro-vias and improve the processing accuracy of the micro-vias.

[0013] Secondly, the present invention also provides a flexible circuit board, including a flexible circuit board via redundancy structure.

[0014] The beneficial effects of this invention are as follows: By applying a redundant via structure to flexible circuit boards, the single via structure used for electrical connection of multiple conductive layers in the flexible circuit board is replaced with an array structure of multiple micro-vias, forming parallel redundancy in the structure. This ensures that during the manufacturing process, when the conductivity of the via structure decreases due to the inflow of semi-fluid colloid, the electrical stability between multiple conductive layers can be maintained through other micro-vias, thereby fundamentally ensuring the circuit stability of the flexible circuit board and ultimately effectively improving the product yield and service life of the flexible circuit board.

[0015] Thirdly, the present invention also provides a method for manufacturing a flexible circuit board, for forming a redundant via structure of the flexible circuit board, comprising the following steps: S1: Provide a flexible circuit board substrate to be processed, the substrate having at least a first conductive layer and a second conductive layer disposed opposite to each other; S2: In a predetermined electrical connection area, a plurality of micro-through holes penetrating the substrate are formed using laser equipment. The plurality of micro-through holes are arranged in a preset pattern, and the diameter of each micro-through hole is equal, ranging from 0.01 mm to 0.05 mm. S3: Perform hole metallization treatment on the plurality of micro-conductive holes to form a conductive path connecting the first conductive layer and the second conductive layer.

[0016] The beneficial effects of this invention are as follows: By using laser equipment to process the flexible circuit board substrate, multiple micro-via structures penetrating its multiple conductive layers are formed on the flexible circuit board substrate, thereby replacing the single via structure formed by traditional mechanical drilling. This results in a structurally redundant parallel micro-via structure on the flexible circuit board substrate. Specifically, by employing laser processing, this invention ensures the feasibility of the micro-via structure's small aperture and precise arrangement. Furthermore, compared to traditional mechanical drilling, laser processing can reduce the heat-affected zone on the flexible circuit board during the formation of micro-vias and improve the processing accuracy of the micro-vias.

[0017] Furthermore, in step S2, the processing parameters of the laser device are set within the following range: The laser power factor ranges from 50% to 120%. The laser frequency ranges from 50 kHz to 110 kHz; The laser power ranges from 5W to 12W; The number of laser processing passes ranges from 5 to 30. The laser scanning speed ranges from 500 mm / s to 1200 mm / s.

[0018] The beneficial effect of adopting the above-mentioned further solution is that by adjusting specific parameters of the laser equipment, the accuracy and efficiency of laser equipment in processing micro-vias on flexible circuit board substrates can be improved.

[0019] Furthermore, in step S2, the number of laser processing passes and the laser scanning speed are adjusted proportionally according to the thickness of the flexible circuit board substrate; wherein, for every 10 μm increase in the thickness of the flexible circuit board substrate, the number of laser processing passes is increased by 1 to 3 times, and / or the laser scanning speed is reduced by 50 to 150 mm / s.

[0020] The beneficial effects of adopting the above-mentioned further solution are: by adjusting the number of laser processing passes and / or laser scanning speed according to the flexible circuit board substrates of different thicknesses, a micro-hole array with consistent aperture and good hole shape can be stably obtained on flexible circuit board substrates of all thicknesses, which effectively improves the universality and mass production stability of the flexible circuit board manufacturing method.

[0021] Furthermore, in step S2, by monitoring the intensity of plasma emission generated during the laser equipment processing or by measuring the temperature of the processing area in real time, the laser power factor or the laser power is controlled to maintain the temperature of the processing area below the decomposition temperature of the flexible circuit board substrate.

[0022] The beneficial effects of adopting the above-mentioned further solution are: by monitoring the plasma emission intensity (indirectly reflecting the intensity of processing) or directly measuring the temperature, and using this feedback to adjust the laser power, precise control of the thermal effects generated by laser equipment processing is achieved. This ensures that the laser energy is just sufficient to vaporize the material to form micro-vias, while effectively suppressing thermal damage such as ablation and carbonization of the flexible circuit board substrate caused by excess energy, thereby guaranteeing the chemical cleanliness and geometric quality of the micro-via walls.

[0023] Fourthly, the present invention also provides an electronic device, including a flexible circuit board.

[0024] The beneficial effects of this invention are: by applying a flexible circuit board with a via redundancy structure to electronic devices, and in combination with the via redundancy structure, the service life of the flexible circuit board in the electronic device is effectively improved. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a schematic diagram of the redundant via structure in this invention, which includes three micro-vias. Figure 2 This is a schematic diagram of the redundant via structure in this invention, which includes four micro-vias. Figure 3 This is a schematic diagram of the redundant via structure in this invention, which includes 5 micro-vias; Figure 4 This is a flowchart of the manufacturing method of the flexible circuit board in this invention.

[0027] The attached diagram lists the components represented by each number as follows: 10. Redundant via structure; 11. Micro-via; 20. First conductive layer; 30. Second conductive layer. Detailed Implementation

[0028] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0029] Example 1 refer to Figures 1-3 The present invention provides a redundant via structure for a flexible circuit board for electrically connecting a first conductive layer 20 and a second conductive layer 30 of the flexible circuit board. The redundant via structure 10 is composed of a plurality of independent micro vias 11. The plurality of micro vias 11 are arranged in a preset pattern in the corresponding electrical connection areas of the first conductive layer 20 and the second conductive layer 30. The diameter of each micro via 11 is equal and the diameter ranges from 0.01 mm to 0.05 mm.

[0030] In this embodiment, reference Figure 1 A via redundancy structure 10 is formed on the flexible circuit board for electrically connecting its first conductive layer 20 and second conductive layer 30. Specifically, the via redundancy structure 10 is used to electrically connect the top copper foil and the bottom copper foil. The via redundancy structure 10 consists of three independent micro-vias 11. All three micro-vias 11 are located in the same pad area where the first conductive layer 20 and the second conductive layer 30 need to be interconnected, and are arranged according to a preset equilateral triangle shape. The three micro-vias 11 have the same aperture of 0.03 mm. Furthermore, the micro-vias 11 penetrate the flexible dielectric substrate, optionally using a polyimide flexible dielectric substrate. After the vias are metallized, these three micro-vias 11 together form three parallel conductive channels for connecting the upper and lower conductive layers.

[0031] It needs to be explained that, compared to traditional mechanical drilling to form a single through-hole connecting the upper and lower conductive layers, this invention replaces a single channel with multiple parallel channels. This allows current to still be transmitted unimpeded through the other two unobstructed micro-through-holes 11 even when the colloid in the cover film flows into and completely blocks one of the micro-through-holes 11 in subsequent processes. This structural redundancy design eliminates the risk of "single-point failure" at the physical level, thus solving the problem of hole wall blockage or increased resistance caused by colloid flowing into the through-hole. In other words, compared to the traditional single-hole structure, the multi-hole parallel redundant structure of this invention achieves an order-of-magnitude improvement in connection reliability.

[0032] The beneficial effects of this invention are as follows: by replacing the traditional single via with an array of multiple micro-vias arranged in a preset pattern, a parallel redundancy is created in the structure. Therefore, during the manufacturing process, when one or more micro-vias 11 are blocked or covered by subsequent processes (such as cover film lamination), the remaining micro-vias 11 can still effectively maintain the interlayer electrical connection of multiple conductive layers. This fundamentally solves the problem of single-point failure caused by semi-fluid colloid flowing into the vias during manufacturing, leading to reduced circuit reliability and significantly improving product yield and service life.

[0033] Preferred, Reference Figures 2-3 The plurality of micro-conducting holes 11 are arranged in a cross shape.

[0034] In this embodiment, reference Figure 2 The redundant via structure 10 consists of four micro-vias 11, which are arranged in a cross shape. Specifically, the four micro-vias 11 are located at the four ends of a virtual cross: top, bottom, left, and right. The diameters of the four micro-vias 11 are equal, all being 0.02 mm.

[0035] It should be explained that the "cross-shaped" arrangement in this embodiment creates a symmetrical and uniform distribution of the four micro-channels 11 within the connection area. During the pressing of the cover film, the symmetrical structure formed by the "cross-shaped" arrangement helps to evenly distribute the pressing stress in four directions, preventing stress concentration that could lead to excessive compression or filling of any particular channel. This uniform stress distribution ensures that the probability and extent of colloid inflow into each channel are consistent, further guaranteeing that even if partial blockage occurs, the remaining channels can maintain optimal operating conditions, thereby "optimizing the reliability of redundant connections" and making the structural design more robust.

[0036] By arranging multiple micro-vias 11 in a cross shape, the arrangement of the multiple micro-vias 11 in this invention provides a uniform and symmetrical hole distribution on the plane, thereby optimally dispersing process stresses (such as cover film pressure) from various directions, and making the conductive path more uniform and stable on the two-dimensional plane, further optimizing the reliability of redundant connections.

[0037] Preferred, Reference Figures 2-3 The cross-shaped arrangement includes a central micro-through hole 11 and four micro-through holes 11 arranged around the central micro-through hole 11 in four mutually perpendicular directions, together forming an array of five micro-through holes 11.

[0038] In this embodiment, reference Figure 2 The via redundancy structure 10 consists of a standard cross-shaped array of five microvias 11. The five microvias 11 include a central microvia 11 located at the geometric center of the pad, and four peripheral microvias 11 located directly above, below, to the left, and to the right of the central microvia. The diameter of each of the five microvias 11 is 0.025 mm. Together, the five vias form a tight, symmetrical pattern.

[0039] It should be explained that this embodiment, while solving the problem of microvia 11 blockage, also considers "space efficiency." Specifically, by arranging the central hole and four directional holes of the microvia 11 within a limited pad area, five parallel pathways can be accommodated while maintaining a symmetrical layout. This layout maximizes the utilization of the connection area, ensuring that even in extreme cases (e.g., excessive cover film colloid, or simultaneous blockage of two diagonal holes by foreign matter), at least three holes (the central hole and the two holes on the other side) can still maintain effective connection. This provides optimal structural assurance for "ensuring multiple effective pathways even in extreme cases," thereby improving the reliability of connecting the upper and lower conductive layers.

[0040] By employing a centrally located, cross-shaped array of five holes, this invention achieves a specific structure that balances optimal redundancy and space efficiency. The layout of the central hole and the four directional holes maximizes the utilization of the connection area, ensuring multiple effective pathways even in extreme conditions.

[0041] Preferred, Reference Figures 1-3 The micro-conductive via 11 is a blind hole or through hole formed by laser processing.

[0042] In this embodiment, the micro-vias 11 are all fabricated using ultraviolet laser equipment. Optionally, a 355nm ultraviolet laser is used, and a high-precision galvanometer control system is employed to ablate and form the patterned micro-vias 11 on a flexible polyimide substrate. The fabricated micro-vias 11 can be through-holes penetrating the substrate or blind holes reaching only the intermediate conductive layer.

[0043] It needs to be explained that the hole diameter limit of mechanical drilling in the background technology is 0.05 mm, making it impossible to achieve smaller holes. This invention requires hole diameters as small as 0.01-0.05 mm, with precise arrangement, which can be better achieved using laser processing (especially cold-processing ultraviolet lasers). Specifically, laser processing overcomes the physical size limitations of mechanical drill bits, thus enabling the fabrication of micro-through holes 11 with even smaller diameters. Furthermore, the heat-affected zone (HAZ) of laser processing is much smaller than the stress-affected zone of mechanical drilling, reducing damage to the soft polyimide substrate and minimizing damage to the material surrounding the micro-through holes 11, thus improving hole wall quality. Finally, by program-controlled laser path, sub-micron level positioning accuracy can be achieved, reliably processing the "preset pattern" and ensuring the accurate realization of the redundant structural design.

[0044] By using laser equipment to process the flexible circuit board to form micro-vias 11, the feasibility of small aperture and precise arrangement structure is ensured. At the same time, the laser processing method used in this invention, compared with the traditional mechanical drilling method, can reduce the heat-affected zone of the flexible circuit board when processing the micro-vias 11, and can also improve the processing accuracy of the micro-vias 11.

[0045] In some embodiments, reference Figures 1 to 3 The micro-vias 11 are filled with conductive paste. The micro-vias 11 are through-holes penetrating the flexible circuit board substrate. The conductive paste, after curing, forms a solid conductive filling structure. This filling structure is integrally formed with the flexible circuit board substrate, and its top and bottom surfaces are coplanar with the upper and lower surfaces of the flexible circuit board substrate, respectively, thus maintaining flatness. By filling and curing with conductive paste, the micro-vias 11 are completely filled. This structural design effectively prevents the semi-fluid colloid of the cover film, which is under high temperature and high pressure during subsequent assembly processes, from flowing into the micro-vias 11. Simultaneously, the filled surface keeps the flexible circuit board substrate flat overall, which not only facilitates the mounting and pressing of the cover film but also improves the yield rate of subsequent surface mount processes.

[0046] Example 2 refer to Figures 1-3 Based on Embodiment 1, the present invention also provides a flexible circuit board, including a flexible circuit board via redundancy structure 10.

[0047] In this embodiment, reference Figure 3 The flexible circuit board is a double-sided flexible circuit board used in smartphone camera modules. Specifically, on the board body of the double-sided flexible circuit board, multiple redundant through-hole structures 10, such as the 5-hole cross array structure described in Embodiment 3, are set on the key signal transmission path connecting the image sensor and the motherboard interface to realize the interconnection between the top layer traces and the bottom layer traces.

[0048] It should be explained that the flexible circuit board product in this example employs a redundant structure at its critical internal interconnect points. Even when the camera module is repeatedly bent or the phone is dropped and impacted, and individual interconnect points experience performance degradation due to stress or manufacturing defects, the redundant design ensures normal circuit function. This fundamentally guarantees the circuit stability of modules using this double-sided flexible circuit board, reduces the overall failure rate caused by interconnect failures, and thus "effectively improves the product yield and lifespan of the flexible circuit board."

[0049] The beneficial effects of this invention are as follows: By applying the redundant via structure 10 to a flexible circuit board, the single via structure used for electrical connection of multiple conductive layers in the flexible circuit board is replaced with an array structure of multiple micro-vias, forming parallel redundancy in the structure. This ensures that during the manufacturing process, when the conductivity of the via structure decreases due to the inflow of semi-fluid colloid, other micro-vias can maintain stable electrical connections between multiple conductive layers, thereby fundamentally ensuring the circuit stability of the flexible circuit board and ultimately effectively improving the product yield and service life of the flexible circuit board.

[0050] Example 3 refer to Figure 4 Based on Embodiments 1 and 2, the present invention also provides a method for manufacturing a flexible circuit board, for forming a redundant via structure 10 of the flexible circuit board, comprising the following steps: S1: Provide a flexible circuit board substrate to be processed, the substrate having at least a first conductive layer 20 and a second conductive layer 30 disposed opposite to each other; Specifically, prepare a double-sided copper-clad polyimide flexible board, with a substrate thickness of 25μm and a copper thickness of 12μm.

[0051] S2: In the predetermined electrical connection area, a plurality of micro-through holes 11 penetrating the substrate are formed by using laser equipment. The plurality of micro-through holes 11 are arranged in a preset pattern, and the aperture of each micro-through hole 11 is equal, ranging from 0.01mm to 0.05mm. Specifically, an ultraviolet laser processing machine is used to control the laser beam to scan and drill holes sequentially at the pad positions defined in the photoplotting program, forming five micro-through holes 11 arranged in a cross shape, each with a diameter of 0.025mm.

[0052] S3: Perform hole metallization treatment on the plurality of micro-through holes 11 to form a conductive path connecting the first conductive layer 20 and the second conductive layer 30.

[0053] Specifically, the board undergoes plasma desmearing treatment, followed by chemical copper plating and electroplating to form a complete conductive layer within the micro-via 11, thus achieving electrical connection between the upper and lower copper layers.

[0054] It should be explained that the present invention systematically replaces the traditional "mechanical drilling + hole metallization" process by using a specific combination of "laser processing + hole metallization", thereby forming a redundant structure of multiple micro-through-hole arrays arranged in a preset pattern, which improves the reliability of electrical connection between the upper and lower copper layers. By using laser processing, the feasibility of the micro-diameter and precision pattern of the micro-through-hole 11 can be ensured.

[0055] The beneficial effects of this invention are as follows: By using laser equipment to process the flexible circuit board substrate, multiple micro-vias 11 are formed through its multiple conductive layers, replacing the traditional single via structure formed by mechanical drilling. This results in a structurally redundant parallel micro-via 11 structure on the flexible circuit board substrate. Specifically, by employing laser processing, this invention ensures the feasibility of the micro-aperture and precise arrangement of the micro-vias 11. Furthermore, compared to traditional mechanical drilling, laser processing can reduce the heat-affected zone on the flexible circuit board during the formation of the micro-vias 11 and improve the processing accuracy of the micro-vias 11.

[0056] Preferably, in step S2, the processing parameters of the laser device are set within the following range: The laser power factor ranges from 50% to 120%. The laser frequency ranges from 50 kHz to 110 kHz; The laser power ranges from 5W to 12W; The number of laser processing passes ranges from 5 to 30. The laser scanning speed ranges from 500 mm / s to 1200 mm / s.

[0057] In this embodiment, in step S2, to process a 0.025mm hole on a 25μm polyimide substrate, the laser equipment parameters are set as follows: The laser power factor is 80%. The laser frequency is 80 kHz; The laser power is 8 W; The laser processing is performed in 15 passes. The laser scanning speed is 800 mm / s.

[0058] It needs to be explained that when laser equipment processes flexible materials, by selecting specific parameters, the laser equipment can remove the material at a sufficient speed and with an appropriate number of passes. At the same time, by using appropriate power and frequency to control the heat input, the potential problem of damage to the substrate caused by improper laser parameters can be avoided. This ensures that the micro-through hole 11 has a smooth and clean hole wall, thereby solving the problem that if the power or energy is too low, the material cannot be effectively vaporized, resulting in blocked holes or irregular hole shapes; while if it is too high, it will cause carbonization and scorching of the substrate, affecting the metallization bonding force.

[0059] By adjusting specific parameters of the laser equipment, the accuracy and efficiency of processing micro-vias on flexible circuit board substrates can be improved.

[0060] Preferably, in step S2, the number of laser processing passes and the laser scanning speed are adjusted proportionally according to the thickness of the flexible circuit board substrate; wherein, for every 10 μm increase in the thickness of the flexible circuit board substrate, the number of laser processing passes is increased by 1 to 3 times, and / or the laser scanning speed is reduced by 50 to 150 mm / s.

[0061] In this embodiment, when processing a 50μm thick polyimide substrate, the substrate thickness is increased by 25μm (relative to a 25μm baseline). The adjustment rule is: for every 10μm increase in thickness, the number of processing passes increases by 2, and the scanning speed decreases by 100mm / s. Therefore, the laser parameters are adjusted as follows: Number of laser processing passes: 15 passes (baseline) + (25μm / 10μm) * 2 passes = 15 + 5 = 20 passes Laser scanning speed: 800 mm / s (reference) - (25μm / 10μm) * 100 mm / s = 800 - 250 = 550 mm / s.

[0062] By adjusting the number of laser processing passes and / or laser scanning speed according to the flexible circuit board substrates of different thicknesses, a micro-hole array with consistent aperture and good hole shape can be stably obtained on flexible circuit board substrates of all thicknesses, effectively improving the universality and mass production stability of the flexible circuit board manufacturing method.

[0063] Preferably, in step S2, the laser power factor or the laser power is controlled by monitoring the plasma luminescence intensity generated during the laser equipment processing or by measuring the temperature of the processing area in real time, so that the temperature of the processing area is maintained below the decomposition temperature of the flexible circuit board substrate.

[0064] In this embodiment, during the laser processing in step S2, a spectral sensor is integrated to monitor the plasma luminescence intensity generated at the laser application point in real time. A luminescence intensity threshold corresponding to slight vaporization of the substrate (ideal processing state) is set. When the monitored intensity exceeds the threshold (indicating excessive energy and potential ablation), the control system immediately reduces the laser power factor proportionally (e.g., by 1% each time); when the intensity is below the threshold (indicating insufficient energy and incomplete material removal), the power factor is increased. This real-time feedback control ensures that the processing process remains within the optimal energy range, guaranteeing that the processing point temperature is below the decomposition temperature of polyimide.

[0065] By monitoring the plasma emission intensity (indirectly reflecting the intensity of processing) or directly measuring the temperature, and using this feedback to adjust the laser power, precise control of the thermal effects generated by laser equipment processing is achieved. This ensures that the laser energy is just sufficient to vaporize the material to form the micro-via 11, while effectively suppressing thermal damage such as ablation and carbonization of the flexible circuit board substrate caused by excess energy, thereby guaranteeing the chemical cleanliness and geometric quality of the micro-via 11 hole wall.

[0066] Example 4 Based on Embodiment 2, the present invention also provides an electronic device, including a flexible circuit board.

[0067] The beneficial effects of the present invention are: by applying the flexible circuit board with the via redundancy structure 10 to electronic devices, and in combination with the setting of the via redundancy structure 10, the service life of the flexible circuit board in the electronic device is effectively improved.

[0068] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A redundant via structure for a flexible circuit board, used for electrically connecting a first conductive layer and a second conductive layer of the flexible circuit board, characterized in that: The redundant via structure consists of multiple independent micro-vias, which are arranged in a preset pattern in the corresponding electrical connection areas of the first conductive layer and the second conductive layer. Each micro-via has the same aperture, and the aperture ranges from 0.01 mm to 0.05 mm.

2. The flexible circuit board via redundancy structure according to claim 1, characterized in that, The multiple micro-vias are arranged in a cross shape.

3. The flexible circuit board via redundancy structure according to claim 2, characterized in that, The cross-shaped arrangement includes a central micro-via and four micro-vias arranged around the central micro-via in four mutually perpendicular directions, together forming an array of five micro-vias.

4. The flexible circuit board via redundancy structure according to any one of claims 1-3, characterized in that, The micro-through hole is a blind hole or through hole formed by laser processing.

5. A flexible circuit board, characterized in that, Includes a flexible circuit board via redundancy structure as described in any one of claims 1-4.

6. A method for manufacturing a flexible circuit board, used to form a redundant via structure for the flexible circuit board as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Provide a flexible circuit board substrate to be processed, the substrate having at least a first conductive layer and a second conductive layer disposed opposite to each other; S2: In a predetermined electrical connection area, a plurality of micro-through holes penetrating the substrate are formed using laser equipment. The plurality of micro-through holes are arranged in a preset pattern, and the diameter of each micro-through hole is equal, ranging from 0.01 mm to 0.05 mm. S3: Perform hole metallization treatment on the plurality of micro-conductive holes to form a conductive path connecting the first conductive layer and the second conductive layer.

7. The manufacturing method according to claim 6, characterized in that, In step S2, the processing parameters of the laser equipment are set within the following range: The laser power factor ranges from 50% to 120%. The laser frequency ranges from 50 kHz to 110 kHz; The laser power ranges from 5W to 12W; The number of laser processing passes ranges from 5 to 30. The laser scanning speed ranges from 500 mm / s to 1200 mm / s.

8. The manufacturing method according to claim 7, characterized in that, In step S2, the number of laser processing passes and the laser scanning speed are adjusted proportionally according to the thickness of the flexible circuit board substrate; wherein, for every 10 μm increase in the thickness of the flexible circuit board substrate, the number of laser processing passes is increased by 1 to 3 times, and / or the laser scanning speed is reduced by 50 to 150 mm / s.

9. The manufacturing method according to claim 6 or 7, characterized in that, In step S2, by monitoring the intensity of plasma emission generated during the laser equipment processing or by measuring the temperature of the processing area in real time, the laser power factor or the laser power is controlled to keep the temperature of the processing area below the decomposition temperature of the flexible circuit board substrate.

10. An electronic device, characterized in that, Including the flexible circuit board as described in claim 5.

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