Flexible printed circuit boards and their fabrication methods

Abstract

This invention discloses a flexible circuit board and its preparation method. The preparation method includes: obtaining a fiberglass cloth carrier and a flexible circuit board to be baked; placing the flexible circuit board to be baked on the surface of the fiberglass cloth carrier; synchronously winding the fiberglass cloth carrier and the flexible circuit board to be baked together to form a roll; and baking the roll to obtain a baked flexible circuit board. In this invention, by wrapping the flexible circuit board to be baked with fiberglass cloth and then winding and baking it, the flexible circuit board to be baked in the roll is completely and tightly bonded to the fiberglass cloth carrier, thereby limiting the free deformation of the ultra-thin PI substrate layer in the flexible circuit board to be baked, balancing the thermal stress on the board surface, and suppressing heat-induced wrinkles and warping from the source.

Description

Technical Field

[0001] This invention relates to the field of circuit board technology, and in particular to a flexible circuit board and its preparation method. Background Technology

[0002] Flexible printed circuit boards (FPCBs) are widely used in consumer electronics and automotive electronics due to their lightweight and bendable properties. To meet the higher requirements of end products for bending performance, some high-end FPCBs use ultra-thin polyimide films as the substrate insulation layer, for example, polyimide films with a thickness of only 12.5 μm. However, such ultra-thin substrates have extremely poor rigidity and significant thermal expansion and contraction stress after heating, making them prone to surface wrinkles and warping during the baking and leveling process. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a flexible circuit board and a method for preparing the same, so as to reduce the appearance defects such as wrinkles and warping.

[0004] In a first aspect, the present invention provides a method for fabricating a flexible circuit board. The fabrication method includes: Obtain the fiberglass cloth carrier and the flexible circuit board to be baked; The flexible circuit board to be baked is placed on the surface of the fiberglass cloth carrier; The fiberglass cloth carrier and the flexible circuit board to be baked are simultaneously wound into a roll. The material roll is baked to obtain a baked flexible circuit board.

[0005] In one implementation of the first aspect, after obtaining the fiberglass cloth carrier and the flexible circuit board to be baked, the method further includes: Clean the oven tray and lay the fiberglass cloth carrier flat on the cleaned oven tray; Wipe and clean the surface impurities on the fiberglass cloth carrier.

[0006] In one implementation of the first aspect, the flexible circuit board to be baked has a circuit surface and a non-circuit surface; Correspondingly, placing the flexible circuit board to be baked on the surface of the fiberglass cloth carrier includes: The circuit surface is covered on the fiberglass cloth carrier, and the non-circuit surface is oriented toward the side away from the fiberglass cloth carrier.

[0007] In one implementation of the first aspect, placing the flexible circuit board to be baked on the surface of the fiberglass cloth carrier includes: Multiple flexible circuit boards to be baked are arranged in an array on the surface of the fiberglass cloth carrier; wherein, there is a first spacing between two adjacent flexible circuit boards to be baked, and the first spacing is greater than or equal to a preset distance.

[0008] In one implementation of the first aspect, one end of the fiberglass cloth carrier has a roll; Correspondingly, the fiberglass cloth carrier and the flexible circuit board to be baked are simultaneously wound into a roll to form a material roll, including: The roller is driven to rotate around its own central axis so that the fiberglass cloth carrier and the flexible circuit board to be baked are wound onto the roller layer by layer synchronously, thereby forming the material roll.

[0009] In one implementation of the first aspect, after the fiberglass cloth carrier and the flexible circuit board to be baked are simultaneously wound into a roll, the method further includes: sealing the opening of the roll with high-temperature adhesive tape.

[0010] In one implementation of the first aspect, the material roll is baked to obtain a baked flexible circuit board, comprising: The material roll is baked at a constant temperature in an oven under preset baking conditions. After completing the constant temperature baking process, the roll is removed from the oven and placed in a room temperature, dust-free area to allow it to warm up. After the entire roll of material has cooled to the preset temperature, the high-temperature tape is removed and the fiberglass cloth carrier is unfolded to take out the baked flexible circuit board.

[0011] In one implementation of the first aspect, the preset baking conditions are: a baking temperature of 150℃±10℃ and a constant temperature baking time of 120min±30min.

[0012] Secondly, the present invention provides a flexible circuit board. The flexible circuit board is prepared according to the preparation method described above.

[0013] In one implementation of the second aspect, a single-layer region is included, the single-layer region comprising a substrate insulating layer, a first copper layer, and an ink insulating layer, wherein the substrate insulating layer and the ink insulating layer are respectively disposed on opposite sides of the first copper layer.

[0014] The beneficial effects of this invention are as follows: Using fiberglass cloth as a flexible constraint carrier, the flexible circuit board to be baked is wrapped in the fiberglass cloth and then wound for baking, thereby ensuring a completely tight fit between the flexible circuit board to be baked and the fiberglass cloth carrier in the roll (without gaps inside the roll). Based on this, during the baking process, the fiberglass cloth carrier restricts the free deformation of the ultra-thin PI substrate layer (i.e., the PI-based insulating layer) in the flexible circuit board to be baked, balancing the thermal stress on the board surface and suppressing heat-induced wrinkles and warping from the source. Attached Figure Description

[0015] Figure 1 This is a flowchart of the steps in a method for preparing a flexible circuit board according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of a flexible circuit board to be baked placed on a fiberglass cloth carrier.

[0017] Figure 3 This is a schematic diagram of the structure of a flexible circuit board disclosed in an embodiment of the present invention.

[0018] Label Explanation: 1. Fiberglass cloth carrier; 11. Roll; 2. Flexible circuit board to be baked; 3. Flexible circuit board; 31. Double-sided board area; 32. Substrate insulating layer; 33. First copper layer; 34. Second copper layer; 35. First cover film layer; 36. Second cover film; 37. Single-layer area; 38. Ink insulating layer. Detailed Implementation

[0019] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0020] To facilitate understanding of the technical solutions provided in the embodiments of the present invention by those skilled in the art, the relevant technologies are described below: Flexible printed circuit boards (such as double-layer flexible printed circuit boards) are widely used in consumer electronics, automotive electronics and other fields due to their bendability and lightweight characteristics. To meet the higher requirements of end products for bending performance, some high-end flexible printed circuit boards use ultra-thin polyimide film as the substrate insulation layer, for example, using polyimide film with a thickness of only 12.5μm.

[0021] However, such ultra-thin substrates are extremely thin and have poor rigidity. When heated, they undergo significant changes in thermal expansion and contraction stress, making them prone to surface wrinkles and local warping during the baking and leveling process.

[0022] The inventors learned that the following two baking methods are mainly used in the relevant technologies: (1) placing the board directly on the oven tray for free baking: due to the lack of constraint of the ultra-thin PI substrate layer when heated, the shrinkage is uneven and wrinkles are produced in batches; (2) hard plate pressing baking: it is easy to cause secondary defects such as fine line damage, board surface indentation and exposed copper, which cannot meet the quality requirements of high-end terminal products.

[0023] To at least address the aforementioned problems, this invention provides a method for preparing a flexible circuit board. This method first lays a high-temperature resistant fiberglass cloth flat as a flexible carrier. The flexible circuit board 2, with an ultra-thin PI substrate layer (i.e., substrate insulation layer 32), is placed on the fiberglass cloth carrier 1, with its circuit surface facing the carrier 1. Next, the fiberglass cloth carrier 1 and the flexible circuit board 2 are tightly wound and sealed to obtain a roll. Finally, the roll is placed in an oven for baking, and after baking, the entire roll is allowed to cool at room temperature before being unwound. Based on this, by wrapping and constraining the flexible circuit board 2 with its ultra-thin PI substrate layer using the fiberglass cloth carrier 1, heat deformation is mitigated and thermal stress on the board surface is balanced, effectively alleviating the problem of wrinkles and warping of the ultra-thin PI substrate layer in the flexible circuit board 2 during baking. Furthermore, the above baking process is compatible with existing production equipment, does not damage fine circuits or surface coatings, is suitable for mass production of double-layer flexible circuit boards, and significantly improves the yield of the finished product.

[0024] The technical solutions according to the present invention will be described below with reference to specific embodiments and in conjunction with the accompanying drawings.

[0025] Figure 1 This is a flowchart illustrating the steps of a method for fabricating a flexible circuit board according to an embodiment of the present invention. (Refer to...) Figure 1 The preparation method includes steps 100 to 106.

[0026] Step 100: Obtain the fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked; Step 102: Place the flexible circuit board 2 to be baked on the surface of the fiberglass cloth carrier 1; Step 104: The fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked are simultaneously wound into a roll. Step 106: Bake the material roll to obtain a baked flexible circuit board 3.

[0027] As can be seen from the above description, the beneficial effects of this invention are as follows: Using fiberglass cloth as a flexible constraint carrier, the flexible circuit board 2 to be baked is wrapped in fiberglass cloth and then wound and baked, thereby ensuring that the flexible circuit board 2 to be baked in the roll is completely and tightly bonded to the fiberglass cloth carrier 1 (no gaps appear inside the roll). Based on this, during the baking process, the free deformation of the ultra-thin PI substrate layer (i.e., the substrate insulation layer 32 made of PI) in the flexible circuit board 2 is restricted by the fiberglass cloth carrier 1, balancing the thermal stress on the board surface and suppressing heat-induced wrinkles and warping from the source.

[0028] It should be noted that although the winding process described above causes the flexible circuit board 3 to bend, the bending caused by winding is fundamentally different from the wrinkles and warping caused by baking. Winding causes the surface of the flexible circuit board 3 to form a uniform and smooth large-arc bend, which is an elastic deformation. The stress is symmetrical and consistent at all points of the board. After unwinding, the stress is released evenly, and the flexible circuit board 3 naturally springs back to its straight position without leaving permanent deformation. In contrast, baking wrinkles and warping are out-of-plane buckling instability caused by uneven distribution of thermal stress on the surface of the flexible circuit board 3. This is an irreversible plastic deformation, manifested as local bulges or waves. Winding, through the continuous radial constraint of the fiberglass cloth carrier 1, forcibly suppresses the uneven thermal expansion and contraction of the board surface in the horizontal direction throughout the baking process, and distributes the thermal stress evenly along the winding layers, thereby alleviating the generation of wrinkles and warping from the source.

[0029] The following combination Figure 1 The steps in steps 100 to 106, as well as other optional steps, are described in detail.

[0030] Step 100: Obtain the fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked.

[0031] Fiberglass cloth, as a constraint carrier, possesses high-temperature resistance (≥180℃), making it suitable for subsequent baking processes. Furthermore, due to its interwoven warp and weft structure, the warp and weft yarns pull on each other, resulting in excellent dimensional stability at high temperatures and preventing tensile deformation. This ensures continuous constraint on the flexible circuit board 2 throughout the baking process. In contrast, other high-temperature resistant materials (such as silicone) are prone to tensile deformation at high temperatures, leading to a decrease or even loss of constraint force, and thus failing to effectively suppress product warping.

[0032] In an optional embodiment, after obtaining the fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked, the method further includes: cleaning the oven tray, laying the fiberglass cloth carrier 1 flat on the cleaned oven tray, and wiping and cleaning surface impurities on the fiberglass cloth carrier 1. Based on this, by cleaning dust and foreign matter from the surface of the fiberglass cloth carrier 1, a flat and flexible support carrier can be effectively formed.

[0033] As described above, cleaning the oven tray and removing surface dust can effectively reduce the occurrence of dust and impurities being pressed into the tray or trapped between layers during the baking process, thereby preventing indentations, scratches, and poor appearance, and ensuring the surface quality of the product.

[0034] Step 102: Place the flexible circuit board 2 to be baked on the surface of the fiberglass cloth carrier 1.

[0035] In an optional embodiment, the flexible circuit board 2 to be baked has a circuit surface and a non-circuit surface; correspondingly, placing the flexible circuit board 2 to be baked on the surface of the fiberglass cloth carrier 1 includes: covering the circuit surface on the fiberglass cloth carrier 1, and facing the non-circuit surface toward the side away from the fiberglass cloth carrier 1.

[0036] In practical applications, the fiberglass cloth carrier 1 is laid flat on the cleaned oven tray, meaning the lower surface of the flat portion of the fiberglass cloth carrier 1 adheres to the oven tray, while its upper surface is used to place the flexible circuit board 2 to be baked. For the flexible circuit board 2 to be baked, the single-layer area 37 of the flexible circuit board 2 has a circuit surface and a non-circuit surface on opposite sides. When the flexible circuit board 2 to be baked is placed on the flat fiberglass cloth carrier, the circuit surface of the flexible circuit board 2 faces downwards, i.e., towards the fiberglass cloth carrier 1; the non-circuit surface faces the side away from the fiberglass cloth carrier 1, i.e., upwards.

[0037] It should be noted that, since the circuit surface of the single-layer region 37 is covered with ink (i.e., ink insulating layer 38), the thermal shrinkage behavior of the ink and the PI substrate layer is fundamentally different during the baking process. The stress release of the two is not synchronized, causing the flexible circuit board 3 to warp towards the circuit surface after cooling. To address this stress mismatch problem, the present invention arranges the circuit surface towards the fiberglass cloth carrier 1 (that is, after winding, the circuit surface faces the outside of the roll 11). By utilizing the continuous radial constraint applied by the fiberglass cloth carrier 1 during winding, the warping trend is effectively suppressed throughout the baking process, ensuring that the output product remains flat without the need for subsequent secondary leveling treatment, and significantly improving process stability.

[0038] In addition, to improve baking efficiency, multiple flexible circuit boards 2 to be baked can be placed simultaneously on the fiberglass cloth carrier 1, as follows: In an optional embodiment, placing the flexible circuit board 2 to be baked on the surface of the fiberglass cloth carrier 1 includes: arranging a plurality of the flexible circuit boards 2 to be baked in an array on the surface of the fiberglass cloth carrier 1; wherein, there is a first spacing between two adjacent flexible circuit boards 2 to be baked, and the first spacing is greater than or equal to a preset distance.

[0039] Of course, other arrangements can also be adopted, and are not limited here, as long as there is a first spacing greater than or equal to the preset distance between two adjacent flexible circuit boards 2 to be baked. It should be noted that the preset distance can be set and selected according to the actual situation, such as 1cm.

[0040] As described above, arranging the flexible circuit boards 2 to be baked neatly prevents them from tilting or overlapping. This arrangement process reduces the risk of circuit area stacking and squeezing, thus minimizing the risk of circuit damage during the baking process.

[0041] Step 104: The fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked are simultaneously wound into a roll.

[0042] In an optional embodiment, one end of the fiberglass cloth carrier 1 has a roll 11; correspondingly, the fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked are synchronously wound to form a roll, including: driving the roll 11 to rotate around its own central axis so that the fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked are synchronously wound layer by layer on the roll 11 to form the roll.

[0043] In practical applications, such as Figure 3 As shown, the fiberglass cloth carrier 1 on the oven tray has a roll 11 at one end and a flat, free end at the other. It should be noted that the roll 11 is a cylindrical structure formed by the fiberglass cloth carrier 1 itself, serving as the rotating frame during winding. Since the flexible circuit board 2 to be baked is placed on the upper surface of the fiberglass cloth carrier 1, when the roll 11 rotates around its central axis to synchronously and tightly wind the fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked into a roll, the fiberglass cloth, as a flexible constraint carrier, will cover the flexible circuit board 2 located on it, thus ensuring that the flexible circuit board 2 to be baked and the fiberglass cloth carrier 1 are completely and tightly bonded within the roll (without gaps inside the roll), suppressing heat-induced wrinkles and warping from the source. It must be clearly stated that the entire winding process must ensure that the flexible circuit board 2 to be baked and the fiberglass cloth carrier 1 are completely and tightly bonded, and there must be no gaps or looseness inside the roll.

[0044] In an optional embodiment, after the fiberglass cloth carrier 1 and the flexible circuit board 2 to be baked are simultaneously wound into a roll, the method further includes: sealing the opening of the roll with high-temperature adhesive tape.

[0045] Therefore, after the material roll is formed by synchronous winding, high-temperature tape is applied to the opening of the roll to seal it and prevent the roll from loosening or shifting. The high-temperature tape has high-temperature resistance (e.g., ≥150℃) and is suitable for subsequent baking processes.

[0046] Step 106: Bake the material roll to obtain a baked flexible circuit board 3.

[0047] In an optional embodiment, the material roll is baked to obtain a baked flexible circuit board 3, including: Step 200: The material roll is baked at a constant temperature in an oven under preset baking conditions; wherein the preset baking conditions are: baking temperature of 150℃±10℃ and constant temperature baking time of 120min±30min. Step 202: After completing the constant temperature baking process, remove the material roll from the oven and place it in a clean, room-temperature area to allow it to warm up; the warming time should be ≥1.5 hours. Step 204: After the material roll has cooled to the preset temperature, remove the high-temperature tape and unfold the fiberglass cloth carrier 1 to take out the baked flexible circuit board 3.

[0048] In practical applications, the top baking tray of a conventional oven can be removed to place the rolled material horizontally inside the oven tray. The oven door is then closed, and the baking temperature is set to 150℃ with a constant baking time of 120 minutes. After the constant temperature baking process, a slow rewarming and cooling process is performed. Specifically, the material roll is not immediately unpacked but removed from the oven and placed in a clean, room-temperature area for at least 1.5 hours to fully rewarm. Once the material roll has cooled to the preset temperature, the high-temperature tape is removed, the fiberglass cloth carrier 1 is unfolded, and the baked flexible circuit board 3 is taken out and transferred to the next process.

[0049] As described above, baking and other operations can be performed using common ovens, eliminating the need for additional large equipment. The standardized operating procedure (SOP) allows for easy implementation. Furthermore, the entire roll is sealed and cooled slowly after baking, reducing the risk of secondary stress deformation caused by rapid cooling of the flexible circuit board 3, thus further ensuring a smoothing effect.

[0050] Figure 2 This is a schematic diagram of a flexible circuit board according to an embodiment of the present invention. The flexible circuit board 3 is prepared according to the preparation method described above. (Refer to...) Figure 2 The flexible circuit board 3 includes a double-sided panel area 31, which includes a substrate insulating layer 32, a first copper layer 33, a second copper layer 34, a first cover film layer 35, and a second cover film 36. The first copper layer 33 and the second copper layer 34 are respectively disposed on both sides of the substrate insulating layer 32. The first cover film layer 35 is disposed on the side of the first copper layer 33 away from the substrate insulating layer 32, and the second cover film 36 is disposed on the side of the second copper layer 34 away from the substrate insulating layer 32.

[0051] In practical applications, the flexible circuit board 3 may include a double-sided panel area 31 and a single-layer area 37. The double-sided panel area 31 is a double-layer FCCL (Flexible Copper Clad Laminate) structure. A polyimide cover film (i.e., a first cover film layer 35 and a second cover film 36) is laminated onto the top and bottom surfaces of the double-layer FCCL structure, and the surface is treated with immersion gold. It should be noted that the aforementioned double-layer FCCL structure refers to a structure formed by the combination of a substrate insulating layer 32, a first copper layer 33, and a second copper layer 34. It should also be noted that both the first copper layer 33 and the second copper layer 34 are circuit layers.

[0052] In an optional embodiment, the single-layer region 37 includes a substrate insulating layer 32, a first copper layer 33, and an ink insulating layer 38, wherein the substrate insulating layer 32 and the ink insulating layer 38 are respectively disposed on opposite sides (i.e., upper and lower sides) of the first copper layer 33. Since the single-layer region 37 does not have a second copper layer 34, therefore, in the single-layer region 37, as... Figure 2 As shown, the side where the first copper layer 33 is located is the circuit surface, which is covered with an ink insulating layer 38, while the side where the substrate insulating layer 32 is located is the non-circuit surface.

[0053] To make this application easier to understand, an exemplary application is provided below. In this exemplary application, the flexible circuit board 3 adopts a double-layer FCCL structure with a 12.5μm PI substrate layer, with a first cover film laminated on top and a second cover film 36 laminated on the bottom, and the surface layer is treated with immersion gold. Based on this, the anti-wrinkle baking and leveling production process of the above-mentioned flexible circuit board using a 12.5μm ultra-thin PI substrate layer is described in detail below.

[0054] Step S1: Preparing the carrier and cleaning the oven tray Lay the fiberglass cloth roll with the open end of the roll 11 downwards, then lay the fiberglass cloth flat on the oven tray to form a carrier, and wipe and clean the surface of the fiberglass cloth carrier 1 to remove dust and other impurities.

[0055] Step S2, Placing the tray Multiple flexible circuit boards 2 to be baked are placed on the fiberglass cloth carrier 1 with the circuit side facing down (i.e., the non-circuit side facing up). At the same time, the flexible circuit boards 2 to be baked do not overlap each other, and the spacing between adjacent flexible circuit boards 2 to be baked is ≥1cm.

[0056] Step S3, winding and wrapping Rotating the drum 11 around its axis slowly winds the fiberglass cloth carrier 1, tightly winding it together with the flexible circuit board 2 to be baked, forming a roll. This ensures that the surface of each flexible circuit board 2 is completely adhered to the fiberglass cloth, without bulges or gaps. During this process, the roll must be rolled tightly without any looseness, ensuring a close fit between the flexible board and the fiberglass cloth carrier 1. Furthermore, after rolling, the free end (i.e., the opening) of the roll needs to be sealed with high-temperature tape.

[0057] Step S4: Baking at a constant temperature Place the roll horizontally on the oven tray in the oven, set the baking temperature to 150℃ and the constant temperature baking time to 120 minutes, and then bake it in the oven.

[0058] Step S5, slowly warm up After baking, remove the entire roll of material and place it in a dust-free area at room temperature for at least 90 minutes to allow it to fully cool down. After cooling, remove the high-temperature tape and unfold the fiberglass cloth to remove the baked flexible circuit board 3.

[0059] Comparative test: In the conventional free baking process, the wrinkle defect rate of flexible circuit boards is about 18%; after production using the process of this invention, the wrinkle defect rate of flexible circuit boards is reduced to less than 0.5%, the board surface is flat, the dimensional stability meets the customer's tolerance requirements, and there are no secondary defects such as pressure marks and plating scratches.

[0060] In summary, according to the flexible circuit board and its preparation method described in this invention: (1) High-temperature resistant fiberglass cloth is used as a flexible constraint carrier to wrap the flexible circuit board 2 with an ultra-thin PI substrate layer for baking. During the baking process, the fiberglass cloth carrier 1 restricts the free deformation of the ultra-thin PI substrate layer, balances the thermal stress on the board surface, and alleviates the heat-induced wrinkling and warping of the ultra-thin PI substrate layer from the source. (2) After baking, the entire roll is sealed and slowly cooled to reduce the secondary stress deformation caused by rapid cooling of the flexible circuit board, and further ensures the flattening effect. (3) The entire process can be directly mass-produced using existing ovens without the need for additional large equipment. The standardized operation process can be implemented as a standard operating procedure. Moreover, the flexible fiberglass cloth, as an isolation material, will not cause pressure damage or scratches to fine lines or immersion gold plating. Mass production verification shows that it can significantly reduce the wrinkling defect rate of the ultra-thin PI substrate layer. (4) The process is compatible with double-layer flexible circuit boards with ultra-thin PI substrate layers, and is compatible with complex layout structures such as reinforcement areas, dummy copper, and local PI reinforcement, with a wide range of applications. (5) A production process for anti-wrinkle baking and leveling of ultra-thin polyimide substrate flexible circuit board is provided to solve the technical problem that wrinkles and warping are easily generated during the baking process of 12.5μm ultra-thin PI substrate flexible circuit board. The board surface is leveled without damaging the circuit and surface coating, thereby improving the product yield.

[0061] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for fabricating a flexible circuit board, characterized in that, include: Obtain the fiberglass cloth carrier and the flexible circuit board to be baked; The flexible circuit board to be baked is placed on the surface of the fiberglass cloth carrier; The fiberglass cloth carrier and the flexible circuit board to be baked are simultaneously wound into a roll. The material roll is baked to obtain a baked flexible circuit board.

2. The method for preparing a flexible circuit board according to claim 1, characterized in that, After obtaining the fiberglass cloth carrier and the flexible circuit board to be baked, the process also includes: Clean the oven tray and lay the fiberglass cloth carrier flat on the cleaned oven tray; Wipe and clean the surface impurities on the fiberglass cloth carrier.

3. The method for preparing a flexible circuit board according to claim 1, characterized in that, The flexible circuit board to be baked has a circuit surface and a non-circuit surface; Correspondingly, placing the flexible circuit board to be baked on the surface of the fiberglass cloth carrier includes: The circuit surface is covered on the fiberglass cloth carrier, and the non-circuit surface is oriented toward the side away from the fiberglass cloth carrier.

4. The method for preparing a flexible circuit board according to claim 1, characterized in that, Placing the flexible circuit board to be baked on the surface of the fiberglass cloth carrier includes: Multiple flexible circuit boards to be baked are arranged in an array on the surface of the fiberglass cloth carrier; wherein, there is a first spacing between two adjacent flexible circuit boards to be baked, and the first spacing is greater than or equal to a preset distance.

5. The method for preparing a flexible circuit board according to claim 2, characterized in that, One end of the fiberglass cloth carrier has a roll; Correspondingly, the fiberglass cloth carrier and the flexible circuit board to be baked are simultaneously wound into a roll to form a material roll, including: The roller is driven to rotate around its own central axis so that the fiberglass cloth carrier and the flexible circuit board to be baked are wound onto the roller layer by layer synchronously, thereby forming the material roll.

6. The method for preparing a flexible circuit board according to claim 1, characterized in that, After the fiberglass cloth carrier and the flexible circuit board to be baked are simultaneously wound into a roll, the process further includes sealing the opening of the roll with high-temperature adhesive tape.

7. The method for preparing a flexible circuit board according to claim 6, characterized in that, The process of baking the material roll to obtain a baked flexible circuit board includes: The material roll is baked at a constant temperature in an oven under preset baking conditions. After completing the constant temperature baking process, the roll is removed from the oven and placed in a room temperature, dust-free area to allow it to warm up. After the entire roll of material has cooled to the preset temperature, the high-temperature tape is removed and the fiberglass cloth carrier is unfolded to take out the baked flexible circuit board.

8. The method for preparing a flexible circuit board according to claim 7, characterized in that, The preset baking conditions are: baking temperature of 150℃±10℃, and constant temperature baking time of 120min±30min.

9. A flexible circuit board, characterized in that, It is prepared according to any one of claims 1 to 8.

10. The flexible circuit board according to claim 9, characterized in that, It includes a single-layer region, which includes a substrate insulating layer, a first copper layer, and an ink insulating layer, wherein the substrate insulating layer and the ink insulating layer are respectively disposed on opposite sides of the first copper layer.

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