Single-face double-contact FPC production process

Abstract

The invention relates to the field of FPC (Flexible Printed Circuit) production processes, and particularly discloses a single-sided double-contact FPC production process, which comprises the following steps of die cutting of a cover film and coating compounding, the method comprises the following steps: baking, cleaning the back surface, pressing dry films on the two surfaces in a roll-to-roll manner / coating photosensitive oil, exposing LDI in a roll-to-roll manner, developing in a roll-to-roll manner, etching in a roll-to-roll manner, AOI and target punching, cleaning, pressing films in a roll-to-roll manner, pasting reinforcement, pressing in a roll-to-roll manner, cutting, baking, OSP, forming, FQC-FQA, packaging and warehousing, thereby obtaining the single-side double-contact FPC. The manufactured FPC product solves the problems of errors, tension accumulation and front and back pattern offset caused by coiled material deformation in the FPC production process, and solves the problem that efficiency and precision cannot be both considered in a traditional process.

Description

Technical Field

[0001] The present application relates to the field of FPC production technology, and more specifically, to a single-sided double-contact FPC production technology. Background Art

[0002] FPC is a printed circuit suitable for MP3, DVD, digital camera, mobile phone, medical, automotive and aerospace fields, and has the characteristics of free bending, folding, winding, small size, thinness, free movement and expansion. Many flexible circuit boards only design the circuit on one side to meet the circuit board density requirements, but for assembly, windows must be opened on both sides or long slots must be left to leave assembly contacts. The contacts lose the support of the substrate and cannot be wet-etched. Resin must be coated for protection before the circuit is completed. The protective glue is then removed for metal surface treatment. The general single-sided double-contact FPC process in the prior art is as follows: material cutting - cutting / punching covering film - sheet bonding - sheet pressing - sheet target punching - sheet cleaning - sheet lamination - sheet alignment - sheet exposure - sheet development - sheet etching - sheet demolding - sheet AOI - sheet target punching - sheet cleaning - bonding - pressing - baking - cleaning - electrical testing - shape 1 - reinforcement 1 - pressing - reinforcement 2 - pressing - baking - OSP - shape 2 - FQC - FQA - packaging - warehousing and shipment.

[0003] Since double contact requires conductive layers on both sides, precise alignment and step-by-step window opening, reinforcement and surface treatment are required. Therefore, the process is complicated and inefficient. The sheet needs to be moved multiple times. Step-by-step operations such as exposure and reinforcement lead to step-by-step errors, which ultimately affect the overlap between window opening and circuit. It is difficult to ensure the precise alignment of multiple process steps. Complex circuit design and contact point layout will also cause uneven stress in the material during continuous transmission, which in turn causes deformation or wrinkling, making it difficult for roll-to-roll equipment to simultaneously process double-sided pattern transfer and etching, resulting in high manufacturing costs and low quality yield during the production process.

[0004] Therefore, how to provide a single-sided double-contact (hollow board) FPC production process so that the intermediate material can have uniform stress during continuous transmission, without causing deformation or wrinkles, and without excessive movement, so as to adapt to the synchronous transfer and etching of roll-to-roll equipment, is of great value in reducing the process of FPC products, reducing costs, and improving production efficiency. Summary of the Invention

[0005] In order to achieve efficient and high-yield production of single-sided dual-contact FPCs, the present application provides a single-sided dual-contact FPC production process, comprising the following steps: S1: Die-cut cover film - coating composite, high temperature baking and curing: First, the first cover film is die-cut, and the whole roll is windowed to obtain the die-cut cover film. The blackened pure copper foil and the die-cut cover film are composited and subjected to roll-to-roll high temperature curing to obtain the back-side windowed conductive structure; S2: Cleaning the back: Cleaning the residual blackened layer on the back window; S3: Roll-to-roll double-sided dry film pressing / photosensitive oil coating: double-sided film pressing or coating to form a uniform photoresist layer; S4: LDI roll-to-roll exposure: Use the roll-to-roll LDI exposure machine to perform registration exposure so that the front and back windows and circuits coincide; S5: Roll-to-roll development - Use the duplex developer to perform double-sided development; S6: Roll-to-roll etching: Etching and demolding are performed using a double-sided vacuum etching and demolding machine; S7: Roll-to-roll AOI and target punching and cleaning: detect circuit defects, make positioning holes, correct hole position errors, and clean excess impurities; S8: Roll-to-roll lamination - reinforcement - roll-to-roll lamination - cutting - baking; S9: Post-processing process: OSP-appearance-FQC-FQA-packaging-warehousing to obtain single-sided double-contact FPC.

[0006] By adopting the above-mentioned preparation method, roll-to-roll double-sided lamination, exposure, and etching achieve seamless simultaneous processing of two contact points, breaking through the traditional single-sided limitations, reducing manual intervention, contamination, and operational errors, and eliminating the errors caused by traditional process downtime for re-material changes. Laminating blackened copper foil with die-cut cover film simplifies the double-sided structure production process, resolving the traditional process's inability to balance efficiency and precision. LDI exposure combined with target punching achieves precise alignment of front and back windowing and circuitry, addressing the issue of front and back pattern offset caused by roll deformation. Double-sided development and vacuum etching improve uniformity, and double-sided vacuum etching also avoids solution residue from traditional etching. Through optimized laser die-cutting, LDI exposure, coating, and etching processes, the entire roll is processed from substrate windowing to final molding. Die-cutting, windowing, and coating lamination are completed in one step, reducing slitting and handling, enabling continuous roll-to-roll (R2R) production. The improved roll-to-roll process enables ultra-precision, low-cost mass production of FPCs, particularly suitable for high-end applications such as 5G high-frequency flexible circuits and Mini LED backplanes.

[0007] In a specific embodiment, the die-cutting in S1 is laser die-cutting with a wavelength of 355 nm and a power of 10-20 W. The coating includes a slit coating technology and a real-time infrared thickness gauge with a closed-loop thickness control system. The coating speed is 1.5-2.0 m / min, the adhesive layer is an acrylic adhesive with a thickness of 15 μm ± 0.5 μm, the curing temperature is 150-180 ° C, the curing time is 30-60 min, and the curing pressure is 0.5-1.0 MPa. When the coating speed is 1.5 m / min and the thickness of the blackened pure copper foil is 8 μm, the unwinding tension is 4.0-4.2 N / mm 2 , winding tension 3.0-3.2N / mm 2 , dynamically adjust the tension according to the thickness test value of the blackened pure copper foil and the coating thickness. For every ±1μm deviation of the copper thickness, the tension is fine-tuned by ±0.3N / mm 2 When the coating speed fluctuates by ±0.2m / min, the tension is fine-tuned by ±0.1N / mm 2 .

[0008] This preparation method results in burr-free die-cutting, no vibration deviation, high precision, no deformation, and no excessive stress accumulation. The adhesive coating process ensures leveling, no obvious horizontal or vertical streaks, and sufficient curing. Furthermore, low tension during the curing process reduces thermal expansion stress. By dynamically adjusting the unwinding and rewinding tension based on different copper foil thicknesses and coating speeds, the tension of the back-side windowed conductive structure is more uniform, further improving precision.

[0009] In a specific embodiment, the cleaning liquid in S2 is 5-6 wt% NaOH solution, the cleaning temperature is 40-50 ° C, the cleaning speed is 1.0-1.2 m / min, the spray pressure is 1.5-2.0 bar, and the unwinding tension is 4.4-4.8 N / mm 2 , winding tension 2.8-3.4N / mm 2 .

[0010] By adopting the above preparation method, the cleaning is sufficient, no damage occurs, and the stress is released to a certain extent.

[0011] In a specific embodiment, the temperature of the S3 film press is 80-100°C, the pressure is 0.3-0.5 MPa, the speed is 1-2 m / min, the wet film thickness of the coated photosensitive oil is 15-25 μm, and the curing energy is 300-500 mJ / cm 2 , unwinding tension is 3.8-4.2N / mm 2 , winding tension 2.6-3.2N / mm 2 .

[0012] By adopting the above-mentioned preparation method, the pressure of winding and unwinding is adjusted in sections, the tension distribution in the front, back, left and right directions is more even, the edge tension can compensate and suppress the center relaxation to a certain extent, and the tension difference between the center area and the edge area will not be too large while the intermediate product is fully coated. It is more suitable for the preparation of the FPC of this application, compensates for the difference in material ductility, avoids local excessive stretching, the dry film and photosensitive oil are firmly adhered, and the risk of circuit breakage is small.

[0013] In a specific embodiment, the exposure in S4 is laser direct imaging with a power of 7-10 kW and an illumination intensity of 80-400 mJ / cm 2 , unwinding tension is 4.2-4.6N / mm 2 , winding tension 2.8-3.4N / mm 2 .

[0014] By adopting the above-mentioned preparation method, there is no need for a mask plate, and exposure can be directly carried out according to the digital file, avoiding the overprint error of traditional photolithography, avoiding the physical damage and surface contamination that may be caused by traditional methods, forming a preset circuit pattern, and the window opening and circuit overlap highly. The imaging is completed more accurately, and the subtle features of the surface, such as microcracks, micropores and tiny bumps, can be captured more clearly, achieving timely feedback and control, reducing defective products caused by stress accumulation, and is more suitable for the process of this application.

[0015] In a specific embodiment, the developer concentration in S5 is 0.8-1.2% Na2CO3, the temperature is 30-35°C, the spray pressure is 1.5-2.0 bar, the developing time is 60-90 seconds, and the unwinding tension is 4.4-4.8 N / mm 2 , winding tension 3.0-3.6N / mm 2 .

[0016] By adopting the above preparation method, the circuit pattern is clear, with less residue and impurities, which significantly improves the manufacturing accuracy and pattern fineness of the PCB and enhances the long-term stability and anti-interference ability of the product.

[0017] In a specific embodiment, the etching solution in S6 includes one or more of CuCl2 and FeCl3, with a concentration of 2.5-3.5 / L, an etching temperature of 40-50°C, a vacuum degree of -80 to -60 kPa, a flow rate of 1.0-1.2 m / s, and a winding tension of 4.2-4.6 N / mm 2 , winding tension 3.0-3.6N / mm 2 .

[0018] By adopting the above preparation method, the etching is uniform and clear, with no obvious side etching and uniform tension. By limiting the vacuum degree to adsorb the coil, the etching liquid flows evenly, the circuits have better insulation function and the probability of residual copper is small.

[0019] In a specific embodiment, the AOI scanning speed in S7 is 10-15m / min, the resolution is 5μm, the target punching is a CCD vision target punching machine with a resolution of 3-7μm, and the unwinding tension is 4.2-4.6N / mm 2 , winding tension 3.0-3.6N / mm 2 .

[0020] By adopting the above preparation method, defects of intermediate products in the production process can be detected in time and repaired in time, with small deviation and high precision.

[0021] In a specific embodiment, the thickness of the covering film in S8 is 25-50 μm, the pressing temperature is 160-180°C, the pressure is 10-15 MPa, the time is 30-60 minutes, and the unwinding tension is 3.8-4.2 N / mm 2 , winding tension 2.6-3.2N / mm 2 .

[0022] By adopting the above preparation method, the pressing is sufficient, the protection and insulation effect of copper is good, and at the same time the covering film is not too thick, the product has high flexibility and is suitable for the winding and unwinding tension.

[0023] In a specific embodiment, the concentration of the OSP treatment solution in S9 is 85-95%, the film thickness is 0.2-0.5 μm, the treatment temperature is 36-42°C, and the unwinding tension is 3.8-4.2 N / mm 2 , winding tension 2.6-3.2N / mm 2 .

[0024] By adopting the above preparation method, the processing effect is good, the processing temperature is low, the product does not produce bending deformation, and the yield is high.

[0025] In summary, this application has the following beneficial effects: This application combines blackened copper foil with die-cut cover film to produce a single-sided, dual-contact FPC, simplifying the double-sided structure production steps. Roll-to-roll double-sided lamination, exposure, and etching enable seamless simultaneous processing of dual contact points. By coordinating process parameters such as winding and unwinding tension in different steps, this approach breaks through the traditional single-sided limitations and eliminates the errors caused by traditional process downtime for reloading. LDI exposure combined with visual target punching and high-precision dynamic alignment solves the problems of errors and tension accumulation caused by coil deformation, as well as front and back pattern offsets. This addresses the problem of traditional sheet material processes that cannot balance efficiency and precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the process flow provided in Example 1 of the present application; Figure 2 This is a process flow chart for producing single-sided double-contact FPC using traditional sheet materials. DETAILED DESCRIPTION

[0027] To further facilitate understanding of the technical solution of the present invention, several specific embodiments are provided to provide a more detailed description of the technical solution of the present invention. These embodiments are only partial embodiments of the present invention, not all of them. The embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. The following embodiments further illustrate the present invention, but the present invention is not limited thereto.

[0028] The raw materials used in the examples and preparation examples of this application are all conventional commercial brands, or can be prepared according to conventional processes.

[0029] 8μm and 12μm blackened rolled copper foils were purchased from Zhuoliangdi C1100; 10μm polyimide was purchased from Wuxi Shunxuan New Material Technology Co., Ltd. HYS-10; 30μm polyimide cover film was purchased from Dongguan Kaixun New Materials Co., Ltd. X50301-2 photosensitive oil was purchased from Youli PSM-800FY5; OSP treatment liquid was purchased from Kebaoxin KBX108H; acrylic glue was purchased from 8853. Example

[0030] Example 1: S1: Die-cut cover film - coating composite, baking: First, the first cover film 12.5μm polyimide is laser die-cut with a wavelength of 355nm and a power of 10W. The entire roll is opened to obtain a die-cut cover film. The 8μm blackened calendered pure copper foil is coated with 15μm±0.5μm acrylic adhesive at a speed of 1.5m / min and composited with the die-cut cover film. The roll-to-roll aging is carried out at 160℃ and 1.0MPa for 45min, and the unwinding tension is 4.0N / mm 2 , winding tension 3.0N / mm 2 , obtaining a back-side windowed conductive structure; S2: Back cleaning: Clean the residual black layer on the back window, wherein the cleaning liquid is 5wt% NaOH solution, the cleaning temperature is 45°C, the cleaning speed is 1.0m / min, the spray pressure is 1.5bar, and the unwinding tension is 4.6N / mm 2 , winding tension 3.2N / mm 2 .

[0031] S3: Roll-to-roll double-sided dry film pressing / photosensitive oil coating: Double-sided lamination is performed to form a uniform photoresist layer; the lamination temperature is 80°C, the pressure is 0.4 MPa, the speed is 1.5 m / min, the film thickness is 20 μm, and the unwinding tension is 4.0 N / mm 2 , winding tension 3.0N / mm 2 .

[0032] S4: LDI roll-to-roll exposure: A roll-to-roll LDI exposure machine is used for registration exposure, so that the front and back windows and lines coincide with each other. The line width is 40μm and the spacing is 40μm. The exposure is laser direct imaging with a power of 7kW and an illumination intensity of 400mJ / cm 2 , unwinding tension is 4.4N / mm 2 , winding tension 3.2N / mm 2 .

[0033] S5: Roll-to-roll development - double-sided development using a double-sided developer; the developer solution is 1 wt% Na2CO3, the temperature is 30°C, the spray pressure is 1.5 bar, the development time is 70 seconds, and the unwinding tension is 4.4 N / mm 2 , winding tension 3.2N / mm 2 .

[0034] S6: Roll-to-roll etching: Etching and demolding are performed using a double-sided vacuum etching and demolding machine; wherein the etching solution has a CuCl2 concentration of 3.0 / L, an etching temperature of 40°C, a vacuum degree of -80 kPa, a flow rate of 1.0 m / s, and a reel tension of 4.6 N / mm 2 , winding tension 3.6N / mm 2 .

[0035] S7: Roll-to-roll AOI, target punching, and cleaning: Detect circuit defects and correct hole position errors; the AOI scanning speed is 10m / min, the resolution is 5μm, and the target punching is a CCD visual target punching machine with a resolution of 4μm; the positioning hole diameter is 0.5mm, and it is cleaned with 5wt% NaOH solution at a cleaning temperature of 45°C, a cleaning speed of 2.0m / min, a spray pressure of 1.5bar, and an unwinding tension of 4.6N / mm 2 , winding tension 3.6N / mm 2 .

[0036] S8: Roll-to-roll lamination - reinforcement - roll-to-roll lamination - cutting - baking; the polyimide cover film is 30 μm thick, and 15 μm ± 0.5 μm acrylic adhesive is applied at a speed of 1.5 m / min. The polyimide cover film is laminated. The lamination temperature is 170°C, the pressure is 12 MPa, and the time is 30 minutes. The laser cutting is performed at a power of 15 W. The roll-to-roll baking is performed at 160°C and 1.0 MPa for 45 minutes. The unwinding tension is 4.2 N / mm. 2 , winding tension 3.2N / mm 2 .

[0037] S9: Post-processing process: OSP-appearance-FQC-FQA-packaging-warehousing, to obtain single-sided double-contact FPC; wherein the OSP treatment liquid concentration is 90%, the treatment temperature is 40 ° C, and the unwinding tension is 4.0N / mm 2, winding tension 3.0N / mm 2 .

[0038] Performance Testing The single-sided double-contact FPC prepared in Example 1 was subjected to performance testing.

[0039] Among them, tension uniformity test: use non-contact laser tension meter BST-100, take 5 measurement points every 10m (4 points on both sides and 1 point in the center), take a total of 100m, calculate the average tension including the center point and the longitudinal average tension excluding the center point, and then calculate the tension fluctuation rate, full-width tension fluctuation rate = (tension max - tension min) ÷ average tension × 100%, longitudinal tension fluctuation rate = (longitudinal tension max - longitudinal tension min) ÷ longitudinal average tension × 100%; Deformation and alignment accuracy detection: Laser interferometer measures the front and back deformation of the coil (unit: μm / m), and three-dimensional measuring machine (CMM) detects the offset of the front and back patterns; Atomic absorption spectrometer (AAS) was used to measure the copper concentration in the etching solution and then the residual copper rate was determined.

[0040] The test results are shown in Table 1.

[0041] Table 1 Example 2: S1: Die-cut cover film - coating composite, baking: First, the first cover film 12.5μm polyimide is laser die-cut with a wavelength of 355nm and a power of 10W. The entire roll is windowed to obtain the die-cut cover film. The 12μm blackened calendered pure copper foil is coated with 15μm±0.5μm acrylic adhesive at a speed of 1.5m / min and composited with the die-cut cover film. The roll-to-roll aging is carried out at 160℃ and 1.0MPa for 45min, and the unwinding tension is 5.2N / mm 2 , winding tension 4.2N / mm 2 , obtaining a back-side windowed conductive structure; S2: Back cleaning: Clean the residual blackened layer on the back window, wherein the cleaning liquid is 5wt% NaOH solution, the cleaning temperature is 45°C, the cleaning speed is 1.0m / min, the spray pressure is 1.5bar, and the unwinding tension is 4.6N / mm 2 , winding tension 3.2N / mm 2 .

[0042] S3: Roll-to-roll double-sided dry film pressing / photosensitive oil coating: Double-sided lamination is performed to form a uniform photoresist layer; the lamination temperature is 80°C, the pressure is 0.4 MPa, the speed is 1.5 m / min, the film thickness is 20 μm, and the unwinding tension is 4.0 N / mm 2 , winding tension 3.0N / mm2 .

[0043] S4: LDI roll-to-roll exposure: A roll-to-roll LDI exposure machine is used for registration exposure, so that the front and back windows and lines coincide with each other. The line width is 40μm and the spacing is 40μm. The exposure is laser direct imaging with a power of 7kW and an illumination intensity of 400mJ / cm 2 , unwinding tension is 4.4N / mm 2 , winding tension 3.2N / mm 2 .

[0044] S5: Roll-to-roll development - double-sided development using a double-sided developer; the developer solution is 1 wt% Na2CO3, the temperature is 30°C, the spray pressure is 1.5 bar, the development time is 70 seconds, and the unwinding tension is 4.4 N / mm 2 , winding tension 3.2N / mm 2 .

[0045] S6: Roll-to-roll etching: Etching and demolding are performed using a double-sided vacuum etching and demolding machine; wherein the etching solution has a CuCl2 concentration of 3.0 / L, an etching temperature of 40°C, a vacuum degree of -80 kPa, a flow rate of 1.0 m / s, and a reel tension of 4.6 N / mm 2 , winding tension 3.6N / mm 2 .

[0046] S7: Roll-to-roll AOI, target punching, and cleaning: Detect circuit defects and correct hole position errors; the AOI scanning speed is 10m / min, the resolution is 5μm, and the target punching is a CCD visual target punching machine with a resolution of 4μm; the positioning hole diameter is 0.5mm, and it is cleaned with 5wt% NaOH solution at a cleaning temperature of 45°C, a cleaning speed of 2.0m / min, a spray pressure of 1.5bar, and an unwinding tension of 4.6N / mm 2 , winding tension 3.6N / mm 2 .

[0047] S8: Roll-to-roll lamination - reinforcement - roll-to-roll lamination - cutting - baking; the polyimide cover film is 30 μm thick, and 15 μm ± 0.5 μm acrylic adhesive is applied at a speed of 1.5 m / min. The polyimide cover film is laminated. The lamination temperature is 170°C, the pressure is 12 MPa, and the time is 30 minutes. The laser cutting is performed at a power of 15 W. The roll-to-roll baking is performed at 160°C and 1.0 MPa for 45 minutes. The unwinding tension is 4.2 N / mm. 2 , winding tension 3.2N / mm 2 .

[0048] S9: Post-processing process: OSP-appearance-FQC-FQA-packaging-warehousing, to obtain single-sided double-contact FPC; wherein the OSP treatment liquid concentration is 90%, the treatment temperature is 40 ° C, and the unwinding tension is 4.0N / mm 2 , winding tension 3.0N / mm 2 .

[0049] Performance Testing The above performance test was repeated on the single-sided double-contact FPC prepared in Example 2.

[0050] The test results are shown in Table 2.

[0051] Table 2 This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A single-sided double-contact FPC production process, characterized in that: The following steps are involved: S1: Die-cut cover film - coating composite, high temperature baking and curing: First, the first cover film is die-cut, and the whole roll is windowed to obtain the die-cut cover film. The blackened pure copper foil and the die-cut cover film are composited, and then subjected to roll-to-roll high temperature baking and curing to obtain the back window conductive structure; S2: Cleaning the back: Cleaning the residual blackened layer on the back window; S3: Roll-to-roll double-sided dry film pressing / photosensitive oil coating: double-sided film pressing or coating to form a uniform photoresist layer; S4: LDI roll-to-roll exposure: Use the roll-to-roll LDI exposure machine to perform registration exposure so that the front and back windows and circuits coincide; S5: Roll-to-roll development - double-sided development using a double-sided developer; S6: Roll-to-roll etching: Etching and demolding are performed using a double-sided vacuum etching and demolding machine; S7: Roll-to-roll AOI and target punching and cleaning; S8: roll-to-roll lamination - reinforcement - roll-to-roll lamination - cutting - baking; S9: Post-processing process: OSP-appearance-FQC-FQA-packaging-warehousing to obtain single-sided double-contact FPC.

2. The single-sided double-contact FPC production process according to claim 1, characterized in that: The die-cutting in S1 is laser die-cutting with a wavelength of 355nm and a power of 10-20W. The coating includes a slit coating technology and a real-time infrared thickness gauge with a closed-loop thickness control system. The coating speed is 1.5-2.0m / min, the adhesive layer is an acrylic adhesive with a thickness of 15μm±0.5μm, the curing temperature is 150-180℃, the curing time is 30-60min, and the curing pressure is 0.5-1.0MPa. When the coating speed is 1.5m / min and the thickness of the blackened pure copper foil is 8μm, the unwinding tension is 4.0-4.2N / mm², and the winding tension is 3.0-3.2N / mm². The tension is dynamically adjusted according to the thickness detection value of the blackened pure copper foil and the coating thickness. For every ±1μm deviation in copper thickness, the tension is fine-tuned by ±0.3N / mm². When the coating speed fluctuates by ±0.2m / min, the tension is fine-tuned by ±0.1N / mm².

3. The single-sided double-contact FPC production process according to claim 1, characterized in that: The cleaning liquid in S2 is 5-6wt% NaOH solution, the cleaning temperature is 40-50°C, the cleaning speed is 1.0-1.2m / min, the spray pressure is 1.5-2.0bar, the unwinding tension is 4.4-4.8N / mm², and the winding tension is 2.8-3.4N / mm².

4. The single-sided double-contact FPC production process according to claim 1, characterized in that: The S3 medium-pressure film temperature is 80-100°C, the pressure is 0.3-0.5MPa, the speed is 1-2m / min, the wet film thickness of the coated photosensitive oil is 15-25μm, the curing energy is 300-500mJ / cm², the unwinding tension is 3.8-4.2N / mm², and the winding tension is 2.6-3.2N / mm².

5. The single-sided double-contact FPC production process according to claim 1, characterized in that: The exposure in the S4 is laser direct imaging, with a power of 7-10KW, a light intensity of 80-400mJ / cm², an unwinding tension of 4.2-4.6N / mm², and a winding tension of 2.8-3.4N / mm².

6. The single-sided double-contact FPC production process according to claim 1, characterized in that: The developer concentration in S5 is 0.8-1.2% Na2CO3, the temperature is 30-35°C, the spray pressure is 1.5-2.0 bar, the developing time is 60-90 seconds, the unwinding tension is 4.4-4.8 N / mm², and the winding tension is 3.0-3.6 N / mm².

7. The single-sided double-contact FPC production process according to claim 6, characterized in that: The etching solution in S6 includes one or more of CuCl2 and FeCl3, with a concentration of 2.5-3.5 / L, an etching temperature of 40-50°C, a vacuum degree of -80~-60kPa, a flow rate of 1.0-1.2m / s, an unwinding tension of 4.2-4.6N / mm², and a winding tension of 3.0-3.6N / mm².

8. The single-sided double-contact FPC production process according to claim 1, characterized in that: The AOI scanning speed of the S7 is 10-15m / min, the resolution is 5μm, the target punching is a CCD visual target punching machine with a resolution of 3-7μm, the positioning hole diameter is 0.5-1.0mm, the unwinding tension is 4.2-4.6N / mm², and the winding tension is 3.0-3.6N / mm².

9. The single-sided double-contact FPC production process according to claim 1, characterized in that: In the S8, the thickness of the covering film is 25-50 μm, the pressing temperature is 160-180° C., the pressure is 10-15 MPa, the time is 30-60 minutes, the unwinding tension is 3.8-4.2 N / mm², and the winding tension is 2.6-3.2 N / mm².

10. The single-sided double-contact FPC production process according to claim 1, characterized in that: The concentration of the OSP treatment solution in the S9 is 85-95%, the film thickness is 0.2-0.5 μm, the treatment temperature is 36-42°C, the unwinding tension is 3.8-4.2 N / mm², and the winding tension is 2.6-3.2 N / mm².

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