Flexible circuit board production line based on intelligent circulating conveying platform

Abstract

The invention discloses a flexible circuit board production line based on an intelligent circulating conveying platform, and belongs to the technical field of flexible circuit board manufacturing. The production line comprises a rack, and a pressing bracket and a conveying bracket which are arranged on the rack. A hot-pressing unit and a cold-pressing unit are sequentially arranged on the pressing support, and the conveying support is provided with an upper-layer conveying line and a lower-layer conveying line. Automatic transfer of workpieces among hot pressing, cold pressing and lower-layer conveying lines is achieved through a carrying mechanical arm on the portal frame, and a continuous operation flow is formed. Wherein there is an auxiliary cover film, which has support rigidity at room temperature and can melt and decompose at a hot pressing temperature without a separate tear step. In cooperation with the material and the process, low-temperature pressure equalizing, heating decomposition and curing and pressure maintaining curing are sequentially completed in the hot pressing unit, and programmed cooling is conducted in the cold pressing unit. According to the invention, material innovation is deeply coupled with equipment and a process, a film tearing link in a traditional lamination process is thoroughly eliminated, and process simplification, precision improvement and full-automatic continuous production are realized.

Description

Technical Field

[0001] This invention relates to the field of flexible circuit board manufacturing technology, and in particular to a flexible circuit board production line based on an intelligent circulating conveyor platform. Background Technology

[0002] When laminating cover films or reinforcing plates onto flexible circuit boards, extremely high alignment accuracy must be ensured, especially in precision applications such as laser fiber bonding, where alignment accuracy must be controlled within 0.05mm. Existing technologies typically employ complex multi-step processes to achieve this precision.

[0003] The disclosure document CN113411973A, which describes a high-precision alignment process for fiber-optic bonding FPCs, includes the following steps: first, attaching a PET film to the cover film to increase its rigidity and facilitate processing; then, aligning and temporarily attaching it to the FPC using a PIN fixture; followed by cold pressing for initial fixation; then, manually or mechanically removing the PET film; and finally, covering the FPC with a TPX high-temperature film for final hot pressing and curing. While this process improves accuracy, it has drawbacks: the entire process is cumbersome, especially the independent film removal step, which is not only inefficient but may also introduce secondary alignment errors or contamination; moreover, the use of TPX high-temperature film as a resist medium, which is a disposable consumable and therefore costly; and the separate cold and hot pressing steps result in a dispersed equipment layout and poor automation continuity in the entire production line.

[0004] To this end, the applicant has been committed to developing a lamination technology solution that can simplify processes, improve efficiency, ensure accuracy, and is more suitable for automated continuous production. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a flexible circuit board production line based on an intelligent circulating conveyor platform and the supporting materials and processes, which address the problems of cumbersome procedures, low efficiency and risk of secondary alignment in existing FPC lamination processes, so as to achieve integrated, efficient and precise lamination.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In one aspect, a flexible circuit board production line based on an intelligent circulating conveying platform is provided, including a frame, the frame including a pressing bracket and a conveying bracket; The pressing bracket is provided with hot pressing units and cold pressing units arranged in sequence. Both the hot pressing unit and the cold pressing unit include an upper pressing plate and a lower pressing plate that can move relative to each other. The conveyor support is equipped with an upper conveyor line and a lower conveyor line. The upper conveyor line is used to convey the flexible circuit board assembly to be pressed to the hot pressing unit, and the lower conveyor line is used to output the pressed flexible circuit board assembly from the cold pressing unit. The frame also includes a gantry frame located around the hot pressing unit and the cold pressing unit, on which a handling robot is provided to transfer the flexible circuit board assembly between the hot pressing unit, the cold pressing unit and the lower conveyor line.

[0007] In one feasible embodiment, at least one feeding bracket is provided on the side of the conveyor support, and the feeding bracket is provided with a feeding preparation table for placing the flexible circuit board assembly to be pressed, and the outlet of the feeding preparation table is connected to the upper conveyor line.

[0008] In one feasible implementation, a lifting support is provided at the end of the conveyor support, and a hoist is provided inside the lifting support. The hoist is used to lift the pressed components on the lower conveyor line to the outside of the production line.

[0009] In one feasible implementation, a high-precision pin-fitting fixture is installed on the feeding preparation table for a preparatory step, where the auxiliary cover film and FPC are temporarily bonded together using the high-precision pin-fitting fixture. A specially formulated low-melting-point, high-thermal-decomposition-efficiency polymer auxiliary cover film is used as the sacrificial layer. This material rapidly melts and vaporizes at 160℃-180℃, and the decomposition products are harmless small-molecule gases.

[0010] Secondly, the auxiliary covering film is a heat-electrode sacrificial layer, and its preparation materials include, by mass percentage: 40%-60% polyvinyl butyral, 30%-50% polyethylene glycol with a molecular weight of 1000-4000, 5%-15% citrate plasticizer, and 1%-5% modified organosilicon powder or zinc stearate.

[0011] In a feasible manner, the preparation method of the auxiliary covering film is as follows: a. Raw material preparation and pretreatment: Polyvinyl butyral resin was vacuum dried at 80°C for 4 hours to remove moisture; polyethylene glycol was melted at 50°C for later use. b. Ingredient preparation and dissolution: The dried polyvinyl butyral resin was added to a mixed solvent of ethanol and ethyl acetate in a mass ratio of 7:3; then it was placed in a sealed reaction vessel equipped with stirring and heating. Heat to 65±5℃ and stir continuously until the polyethylene glycol is completely dissolved to form a homogeneous adhesive solution. Cool the sealed reactor to 50°C, then add molten polyethylene glycol, plasticizer, and release agent in sequence, and stir continuously for 2-4 hours to form a uniform and transparent slurry. c. Constant temperature stirring and vacuum degassing: Transfer the mixed slurry to a storage tank, maintain the temperature at 50°C and stir slowly; at the same time, turn on the vacuum pump to remove air bubbles from the mixed slurry at -0.095MPa for no less than 1 hour. d Precision casting coating: A precision casting coating machine is used to uniformly coat the degassed slurry onto a polyester release film carrier that is moving at a uniform speed. The parameters used in the precision casting coating machine are as follows: the thickness of the film to be formed is set to 80±5μm, which is precisely controlled by the doctor blade gap; the coating speed is 1.5 m / min to 2 m / min. e-program heating and drying: Once the film has formed, it enters a drying tunnel with three temperature zones, the temperatures of which are 60℃, 80℃, and 100℃ respectively in the conveying direction. The drying time is 3 minutes in the 60℃ zone, 5 minutes in the 80℃ zone, and 10 minutes in the 100℃ zone. This ensures that the solvent is completely and slowly evaporated to prevent pinholes or stress caused by excessively rapid drying.

[0012] f. Cooling, shaping, and winding: After drying, the film to be formed is cooled to room temperature by cooling rollers and peeled off from the polyester release film; and the auxiliary cover film with a final thickness of 50±2μm is wound up for use by the tension control system.

[0013] Thirdly, the hot pressing unit 3 is capable of performing a multi-stage pressing process, including low-temperature pressure equalization, temperature rise curing, and pressure holding curing. Among them, low-temperature pressure equalization is to start the hot pressing unit 3 at a lower temperature below 100℃, so that the auxiliary cover film and FPC are initially tightly bonded; The heating and curing process involves heating the hot-pressing unit 3 to the curing temperature, which is 180°C. In this step, the auxiliary cover film melts, decomposes, and vaporizes. After the auxiliary cover film "disappears," it directly contacts the FPC surface and begins to cure.

[0014] Pressure holding curing involves maintaining pressure at the curing temperature to ensure complete curing of the FPC.

[0015] In a feasible implementation, the cold pressing unit 4 is capable of performing programmed cooling while maintaining pressure. Programmed cooling involves cooling the product under pressure using a preset cooling program until it reaches a temperature at which it can be safely removed.

[0016] The flexible circuit board production line proposed in this invention has the following advantages: By adopting a heat-electrode sacrificial layer, the time-consuming manual or semi-manual step of "film removal," which is essential in traditional processes and may introduce alignment errors and contamination, is completely eliminated. The process of false application, curing, and cooling is integrated into a continuous automated process, which greatly improves production efficiency.

[0017] From initial application to final curing, no secondary relative displacement occurs between the cover film and the FPC. The closed-loop alignment compensation of the CCD ensures the absolute accuracy of the final state, theoretically achieving a higher alignment yield and consistency than traditional processes.

[0018] Eliminating consumables such as TPX high-temperature film reduces equipment footprint and process changeover time, thereby lowering overall production costs. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the flexible circuit board production line of the present invention.

[0020] In the diagram: 1. Pressing support; 2. Conveying support; 3. Hot pressing unit; 4. Cold pressing unit; 5. Upper conveyor line; 6. Lower conveyor line; 7. Gantry; 8. Handling robot; 20. Feeding support; 21. Feeding preparation table; 22. Lifting support; 23. Elevator. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0022] like Figure 1 The diagram shows a schematic of a flexible circuit board production line based on an intelligent circulating conveying platform according to the present invention. As can be seen from the diagram, the flexible circuit board production line based on the intelligent circulating conveying platform includes a frame, which includes a pressing support 1 and a conveying support 2. The pressing bracket 1 is provided with a hot pressing unit 3 and a cold pressing unit 4 arranged in sequence. Both the hot pressing unit 3 and the cold pressing unit 4 include an upper pressure plate and a lower pressure plate that can move relative to each other. The hot pressing unit 3 is a programmable vacuum hot press with heating and multi-stage pressure control functions; the cold pressing unit 4 is a programmable cold press with a water cooling circulation system and pressure holding function.

[0023] The conveyor support 2 is equipped with an upper conveyor line 5 and a lower conveyor line 6. The upper conveyor line 5 is used to transport the flexible circuit board assemblies to be pressed to the hot pressing unit 3, and the lower conveyor line 6 is used to output the pressed flexible circuit board assemblies from the cold pressing unit 4. Both the upper conveyor line 5 and the lower conveyor line 6 are double-speed chain conveyors. A section of the lower conveyor line 6 passes through the lower pressure plate area of ​​the hot pressing unit 3 and the cold pressing unit 4 to allow materials to pass directly through.

[0024] The frame also includes a gantry 7 located around the hot pressing unit 3 and the cold pressing unit 4. The gantry 7 is equipped with a handling robot 8 that can transfer flexible circuit board assemblies between the hot pressing unit 3, the cold pressing unit 4 and the lower conveyor line 6. Linear modules on the gantry 7 drive the handling robot 8 to perform three-dimensional motion.

[0025] In this embodiment, three feeding brackets 20 are provided on the side of the conveying bracket 2. Each feeding bracket 20 is provided with a feeding preparation table 21 for placing the flexible circuit board assembly to be pressed. The outlet of the feeding preparation table 21 is connected to the upper conveyor line 5. The three feeding brackets 20 are staggered on both sides of the conveying bracket 2.

[0026] In this embodiment, a lifting bracket 22 is provided at the end of the conveying bracket 2, and a hoist 23 is provided inside the lifting bracket 22. The hoist 23 is used to lift the pressed components on the lower conveying line 6 to the outside of the production line. Example

[0027] A high-precision pin-fitting fixture is installed on the feeding preparation table 21; it is used for the preparation step, and the auxiliary cover film and FPC are temporarily attached through the high-precision pin-fitting fixture.

[0028] In this embodiment, the auxiliary cover film is a heat-electrode sacrificial layer, and its preparation materials include, by mass percentage: 40%-60% polyvinyl butyral, 30%-50% polyethylene glycol with a molecular weight of 1000-4000, 5%-15% citrate plasticizer, and 1%-5% modified organosilicon powder or zinc stearate.

[0029] In this embodiment, the steps for preparing the auxiliary cover film for the thermally erodible sacrificial layer are as follows: a. Raw material preparation and pretreatment: Polyvinyl butyral resin was vacuum dried at 80°C for 4 hours to remove moisture; polyethylene glycol was melted at 50°C for later use. b. Ingredient preparation and dissolution: The dried polyvinyl butyral resin was added to a mixed solvent of ethanol and ethyl acetate in a mass ratio of 7:3; then it was placed in a sealed reaction vessel equipped with stirring and heating. Heat to 65±5℃ and stir continuously until the polyethylene glycol is completely dissolved to form a homogeneous adhesive solution. Cool the sealed reactor to 50°C, then add molten polyethylene glycol, plasticizer, and release agent in sequence, and stir continuously for 2-4 hours to form a uniform and transparent slurry. c. Constant temperature stirring and vacuum degassing: Transfer the mixed slurry to a storage tank, maintain the temperature at 50°C and stir slowly; at the same time, turn on the vacuum pump to remove air bubbles from the mixed slurry at -0.095MPa for no less than 1 hour. d Precision casting coating: A precision casting coating machine is used to uniformly coat the degassed slurry onto a polyester release film carrier that is moving at a uniform speed. The parameters used in the precision casting coating machine are as follows: the thickness of the film to be formed is set to 80±5μm, which is precisely controlled by the doctor blade gap; the coating speed is 1.5 m / min to 2 m / min. e-program heating and drying: The film is then placed into a drying tunnel with three temperature zones, the temperatures of which are 60°C, 80°C, and 100°C in the conveying direction, respectively; the drying time in the 60°C zone is 3 minutes, the drying time in the 80°C zone is 5 minutes, and the drying time in the 100°C zone is 10 minutes. f. Cooling, shaping, and winding: After drying, the film to be formed is cooled to room temperature by cooling rollers and peeled off from the polyester release film; and the auxiliary cover film with a final thickness of 50±2μm is wound up for use by the tension control system.

[0030] In this embodiment, the performance of the auxiliary cover film was tested: First, thermal properties were analyzed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to confirm the decomposition initiation temperature (target: >160°C), peak temperature, and residual ash content (target: <0.5%). Post-experimental statistics showed that the TGA curve should indicate a mass loss rate of greater than 99% for the auxiliary cover film after holding at a constant temperature of 180°C for 5 minutes. Second, the tensile strength and modulus at room temperature were tested to ensure sufficient support. Post-experimental statistics showed that the elastic modulus of the prepared auxiliary cover film was not less than 1.5 GPa. Third, it was hot-pressed with a standard cover film at 100°C and 0.5 MPa, and the peel strength and subsequent detachment effect after hot pressing were tested. Post-experimental statistics showed that the temporary peel strength of the auxiliary cover film was between 0.1 N / cm and 0.3 N / cm. This strength ensures that it does not peel during the process and allows for natural interface failure after the sacrificial layer decomposes. Example

[0031] The auxiliary cover film prepared in Example 2 was hot-pressed with a standard epoxy adhesive cover film at 90°C and 0.5 MPa to form a temporary composite. This composite was then temporarily attached to an FPC on the feeding preparation table 21 using a pin fixture to form an assembly to be pressed.

[0032] The hot pressing unit 3 can perform a multi-stage pressing process including low-temperature equalization, temperature curing, and pressure holding curing. The low-temperature equalization involves starting the hot pressing unit 3 at a relatively low temperature below 100°C to initially and tightly bond the auxiliary cover film to the FPC. Specifically, a vacuum is drawn to below 10 mbar, the upper and lower pressure plates are heated to 100°C, and a pressure of 0.8 MPa is applied for 60 seconds to achieve initial bonding.

[0033] The heating and curing process involves heating the hot-pressing unit 3 to the curing temperature, which is 180°C; specifically, the temperature is increased to 180°C at a rate of 3°C / minute. During this process, the auxiliary cover film melts and decomposes, and the gas is removed by the vacuum system; the cover film adhesive begins to crosslink and cure. The pressure is maintained at 0.8 MPa.

[0034] Pressure holding curing involves maintaining pressure at the curing temperature to ensure complete curing of the FPC. Maintain a pressure of 0.8 MPa at 180°C for 30 minutes to allow the adhesive to fully cure.

[0035] After pressing, the handling robot 8 moves the workpiece into the cold pressing unit 4. The cold pressing unit 4 can perform programmed cooling while maintaining pressure. Programmed cooling involves cooling the workpiece according to a preset cooling program under maintained pressure until it reaches a safe removal temperature. Specifically, the upper and lower cold plates of the cold pressing unit 4 are closed, maintaining a pressure of 0.8 MPa, and cooling begins at a preset rate of 2°C / minute. When the workpiece temperature drops to 60°C, cooling stops and the pressure is released. The robot 8 removes the final product and places it on the lower conveyor line 6, completing the entire production cycle.

[0036] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A flexible circuit board production line based on an intelligent circulating conveyor platform, comprising a frame, characterized in that, The frame includes a pressing support (1) and a conveying support (2); The pressing bracket (1) is provided with a hot pressing unit (3) and a cold pressing unit (4) arranged in sequence. The hot pressing unit (3) and the cold pressing unit (4) each include an upper pressing plate and a lower pressing plate that can move relative to each other. The conveying bracket (2) is provided with an upper conveying line (5) and a lower conveying line (6). The upper conveying line (5) is used to convey the flexible circuit board assembly to be pressed to the hot pressing unit (3), and the lower conveying line (6) is used to output the pressed flexible circuit board assembly from the cold pressing unit (4). The frame also includes a gantry (7) disposed around the hot pressing unit (3) and the cold pressing unit (4), and the gantry (7) is provided with a handling robot (8) that can transfer the flexible circuit board assembly between the hot pressing unit (3), the cold pressing unit (4) and the lower conveyor line (6).

2. The flexible circuit board production line based on an intelligent circulating conveyor platform according to claim 1, characterized in that, At least one feeding bracket (20) is provided on the side of the conveying bracket (2), and a feeding preparation table (21) for placing the flexible circuit board assembly to be pressed is provided on the feeding bracket (20). The outlet of the feeding preparation table (21) is connected to the upper conveying line (5).

3. The flexible circuit board production line based on an intelligent circulating conveyor platform according to claim 1 or 2, characterized in that, The end of the conveying bracket (2) is provided with a lifting bracket (22), and a hoist (23) is provided inside the lifting bracket (22). The hoist (23) is used to lift the pressed components on the lower conveying line (6) to the outside of the production line.

4. The flexible circuit board production line based on an intelligent circulating conveyor platform according to claim 3, characterized in that, The feeding preparation table (21) is equipped with a high-precision pin-fitting fixture; used for preparation steps, whereby the auxiliary cover film and FPC are falsely bonded together using the high-precision pin-fitting fixture.

5. The flexible circuit board production line based on an intelligent circulating conveyor platform according to claim 4, characterized in that, The auxiliary cover film is a heat-electrode sacrificial layer, and its preparation materials include, by mass percentage: 40%-60% polyvinyl butyral, 30%-50% polyethylene glycol with a molecular weight of 1000-4000, 5%-15% citrate plasticizer, and 1%-5% modified organosilicon powder or zinc stearate.

6. The flexible circuit board production line based on an intelligent circulating conveyor platform according to claim 5, characterized in that, The method for preparing the auxiliary covering film is as follows: a. Raw material preparation and pretreatment: Polyvinyl butyral resin was vacuum dried at 80°C for 4 hours to remove moisture; polyethylene glycol was melted at 50°C for later use. b. Ingredient preparation and dissolution: The dried polyvinyl butyral resin was added to a mixed solvent of ethanol and ethyl acetate in a mass ratio of 7:3; then it was placed in a sealed reaction vessel equipped with stirring and heating. Heat to 65±5℃ and stir continuously until the polyethylene glycol is completely dissolved to form a homogeneous adhesive solution. Cool the sealed reactor to 50°C, then add molten polyethylene glycol, plasticizer, and release agent in sequence, and stir continuously for 2-4 hours to form a uniform and transparent slurry. c. Constant temperature stirring and vacuum degassing: Transfer the mixed slurry to a storage tank, maintain the temperature at 50°C and stir slowly; at the same time, turn on the vacuum pump to remove air bubbles from the mixed slurry at -0.095MPa for no less than 1 hour. d Precision casting coating: A precision casting coating machine is used to uniformly coat the degassed slurry onto a polyester release film carrier that is moving at a uniform speed. The parameters used in the precision casting coating machine are as follows: the thickness of the film to be formed is set to 80±5μm, which is precisely controlled by the doctor blade gap; the coating speed is 1.5 m / min to 2 m / min. e-program heating and drying: The film is then placed into a drying tunnel with three temperature zones, the temperatures of which are 60°C, 80°C, and 100°C in the conveying direction, respectively; the drying time in the 60°C zone is 3 minutes, the drying time in the 80°C zone is 5 minutes, and the drying time in the 100°C zone is 10 minutes. f. Cooling, shaping, and winding: After drying, the film to be formed is cooled to room temperature by cooling rollers and peeled off from the polyester release film; and the auxiliary cover film with a final thickness of 50±2μm is wound up for use by the tension control system.

7. The flexible circuit board production line based on an intelligent circulating conveyor platform according to claim 1 or 4, characterized in that, The hot pressing unit (3) is capable of performing a multi-stage pressing process including low-temperature equalization, temperature rise curing and pressure holding curing; The low-temperature pressure equalization refers to starting the hot-pressing unit (3) at a lower temperature below 100°C, so that the auxiliary cover film is initially tightly bonded to the FPC; The heating and curing process involves heating the hot pressing unit (3) to the curing temperature, which is 180°C. In this step, the auxiliary covering film melts, decomposes, and vaporizes. The pressure-holding curing process involves maintaining pressure at the curing temperature to ensure complete curing of the FPC.

8. The flexible circuit board production line based on an intelligent circulating conveyor platform according to claim 7, characterized in that, The cold pressing unit (4) is capable of performing programmed cooling under pressure holding conditions. The programmed cooling process involves cooling the product under pressure using a preset cooling program until it reaches a temperature at which it can be safely removed.

Images