Flexible circuit board with independent profiled layers and method of processing

Abstract

The application discloses a flexible circuit board with independent outer shape layered board and a processing method. First, interlayer adhesive material is removed in predetermined target areas of a plurality of FPC core boards with completed inner layer circuit to form glue-free window areas; then, laminating and subsequent circuit board body manufacturing are performed; then, preliminary cutting is performed to make each layer relatively spread in the target areas; then, metal isolation plates are sequentially inserted under the layers to be processed, and laser cutting is performed layer by layer to make each layer form different outer shape profiles in the target areas; finally, the isolation plates are removed to obtain finished products. Through the process of combining "selective glue removal" and "insertion type dynamic isolation", the application breaks through the limitation that traditional multi-layer flexible circuit boards can only be integrally formed and processed, and can economically and reliably manufacture flexible circuit boards with independent outer shape of each layer, thereby significantly improving space utilization, optimizing electrical performance and improving heat dissipation.

Description

Technical Field

[0001] This invention relates to the field of circuit board processing, and specifically to a flexible circuit board with an independent outer shape and a processing method thereof. Background Technology

[0002] Flexible circuit boards (PCBs) have been widely used in consumer electronics, automotive electronics, and medical devices due to their advantages such as flexibility, light weight, and small size. As electronic devices become increasingly high-density and multifunctional, higher demands are being placed on flexible circuit boards, leading to a surge in the application of multilayer flexible circuit boards.

[0003] In the manufacturing of multilayer flexible circuit boards, in order to achieve circuit interconnection and physical support between layers, multiple single / double-sided flexible core boards with circuit patterns need to be laminated with adhesive materials such as pure glue to finally form an integral multilayer structure.

[0004] Currently, for multilayer flexible circuit boards that have already undergone lamination, the shaping of their outer contours mainly relies on two mature processes: die-cutting and laser cutting. Both of these processes are "one-piece forming" processes, meaning that all layers of the multilayer board are cut simultaneously using the same set of molds or the same laser cutting path to obtain the final product shape. Therefore, the outer contours of each layer of a multilayer flexible circuit board manufactured using existing processing methods are completely consistent.

[0005] However, the market's increasing demands for space utilization and signal integrity in electronic devices have led to new requirements for multilayer flexible circuit boards: the desire to design different shapes in specific areas on different layers of the same board. For example, staggered designs could free up space for components of different heights, or independent shielding boundaries could be planned for specific signal layers. Existing "one-piece molding" manufacturing methods clearly cannot meet these "layered irregular shape" design requirements.

[0006] If we try to use a step-by-step laser cutting method to achieve layered irregular shapes, that is, after cutting one layer, we then cut the next layer using a different path, we will face a major technical obstacle: when the laser is cutting one layer, its energy will inevitably damage the adjacent other layers, thus making it impossible to guarantee the yield and reliability of the product. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a flexible circuit board with an independent shape layered board and a processing method, which can reliably and efficiently realize that each layer of the multilayer flexible circuit board has a different shape in a specific area.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for fabricating a flexible circuit board with independently shaped layered panels includes the following steps:

[0010] Step 1: Provide multiple FPC core boards and perform preprocessing;

[0011] Multiple FPC core boards with completed inner layer circuitry are provided. Target areas that need to achieve independent shapes are predefined on the FPC core boards. The entire area of ​​the FPC core board includes a common area with a consistent shape and a target area with an independent shape. The independent shape area refers to the area with different shapes between the FPC core boards.

[0012] Treatment of interlayer adhesive material: The target area where the FPC core board needs to achieve an independent shape is predefined on the interlayer adhesive material of the FPC core board. Within the target area, some or all of the adhesive material is removed.

[0013] Multiple FPC core boards are stacked together using a treated interlayer adhesive material, resulting in glue-free window areas on the stacked FPC core boards.

[0014] Step 2: Lamination and FPC main body fabrication;

[0015] The stacked materials are pressed together to form a single multilayer board; standard subsequent processes are then performed on the pressed multilayer board to complete the FPC main body fabrication.

[0016] Step 3: Preliminary cutting and layer pre-separation; Cut along the outer perimeter of the board and the common area where all circuit structure layers have the same shape;

[0017] Step 4, Insertion of isolation protection and layered laser forming; Step 4.1, Insertion of metal isolation plate: For the first circuit structure layer that needs to be cut, insert a metal isolation plate of matching size from the side into the glue-free gap between the first circuit structure layer and the layer below it;

[0018] Step 4.2: Adjust the laser parameters and perform laser cutting on the first circuit structure layer along a predetermined path that is different from the common area;

[0019] Step 4.3, Layer-by-layer processing: Remove the isolation plate under the first layer and insert it between the second layer and the next layer that needs to be processed. Repeat steps 4.1 and 4.2 to cut the second layer with a different shape path. Continue in this way until all circuit structure layers that require a separate shape have been processed. Step 5, Final shaping.

[0020] Remove all the isolation metal plates and clean or micro-process the processing edges; the multilayer flexible circuit board has achieved differentiated design of the outline of each circuit structure layer in the target area.

[0021] In step 1, there are no vent holes in the glue-free window area.

[0022] In step 2, the fabrication of the FPC body includes drilling, hole metallization, application of the outer cover film, and surface treatment.

[0023] In step 2, the FPC body fabrication also includes the fabrication of the outer layer circuit pattern, which is carried out after the hole metallization and before the outer layer cover film is applied.

[0024] In step 3, the initial cutting is performed using die punching or laser cutting.

[0025] A flexible circuit board with an independent shape and layered structure is characterized in that the circuit board is processed by the method described above, the flexible circuit board includes at least two stacked FPC core boards, the at least two FPC core boards are provided with an adhesive area and a glue-free window area, the FPC core boards are bonded to each other in the adhesive area by an adhesive material, and there is no adhesive material between at least two FPC core boards in the glue-free window area, the outer contours of at least two FPC core boards are different from each other in the glue-free window area.

[0026] By adopting the above solution, this invention fundamentally changes the processing mode of "integrated molding" of multilayer flexible circuit boards. Through the preliminary "selective glue removal" design, combined with the subsequent "insertion isolation and layer-by-layer cutting" process, for the first time in economical and reliable industrial production, it is possible to enable different circuit structure layers to have completely independent external outlines within the same circuit board.

[0027] Flexible circuit boards manufactured using the method of this invention can bring direct product-level benefits:

[0028] Improve space utilization: The shape of each layer can be staggered according to the actual height of the assembled components, achieving a more compact stacking in the Z-axis direction and reducing the overall volume of the module.

[0029] Optimize electrical performance: By designing independent, shielded boundary profiles for sensitive signal layers, or by providing a better reference plane for high-speed signals through shape isolation, signal crosstalk can be effectively reduced, and the integrity and stability of transmission can be improved.

[0030] Improved heat dissipation: The staggered layered structure can form micro air channels between the layers, which is conducive to heat dissipation. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the FPC core board shape in this embodiment;

[0032] Figure 2 This is a schematic diagram of the FPC core board stack-up in this embodiment;

[0033] Figure 3 This is a schematic diagram showing the cut-off of the common area of ​​the FPC body in this embodiment;

[0034] Figure 4 This is a schematic diagram of the independent shape cutting of the FPC core board in this embodiment;

[0035] Figure 5 This is a schematic diagram of the product processed in this embodiment.

[0036] Label Explanation:

[0037] First FPC core board 1; Second FPC core board 2; Bonding area 3; Glue-free window area 4; Metal isolation plate 5. Detailed Implementation

[0038] This invention discloses a method for processing a flexible circuit board with an independently shaped layered board, which includes the following steps:

[0039] Step 1: Provide multiple FPC core boards and perform preprocessing.

[0040] We offer multiple pre-fabricated FPC core boards with completed inner layer circuitry. For example... Figure 1 As shown, this embodiment provides two FPC core boards, namely the first FPC core board 1 and the second FPC core board 2. The two ends of the first FPC core board 1 and the second FPC core board 2 have independent shapes, that is, the two ends have different shapes.

[0041] Treatment of interlayer adhesive material: Target areas where the FPC core board needs to achieve an independent shape are pre-defined on the interlayer adhesive material. Within these target areas, some or all of the adhesive material is removed using laser ablation or precision mechanical methods. The entire FPC core board area includes common areas with consistent shapes and target areas with independent shapes. Independent shape areas refer to areas with different shapes between FPC core boards.

[0042] Multiple FPC core boards are stacked together using a treated interlayer adhesive material. A glue-free window region 4 is formed on the stacked FPC core boards, and this glue-free window region 4 has no vent holes. The glue-free window region 4 provides a physical separation interface or a weak bonding interface for the FPC core boards. In this embodiment, the first FPC core board 1 and the second FPC core board 2 are stacked as follows... Figure 2 As shown, after lamination, an adhesive area 3 and a glue-free window area 4 will be formed on the FPC core board.

[0043] Step 2: Lamination assembly and FPC body fabrication.

[0044] First, the stacked materials are pressed together to form a single multilayer board. During the pressing process, the layers in the glued areas are firmly bonded together, while in the glueless window areas 4, the layers are only bonded through physical contact or very weak connections, thus forming a "partially separable" structure inside the board.

[0045] After lamination, standard follow-up processes are performed on the multilayer board to complete the FPC body fabrication. These processes include, but are not limited to: drilling, hole metallization, outer layer circuit pattern fabrication (using DES process), lamination of outer layer cover film (CVL), and surface treatment. At this point, a complete multilayer flexible circuit board with full electrical functionality and separable potential in specific internal areas is obtained.

[0046] Step 3: Preliminary cutting and layer pre-separation.

[0047] Using die-cutting or laser cutting methods, along the outer perimeter of the sheet and the common area with a consistent shape of all FPC core boards (corresponding to...). Figure 3 Cut the thick lines. After this step, the panel frame is removed, but the circuit structure layers in the target area can be relatively separated because there is no strong adhesion. At the same time, the entire board still maintains the physical connection state of PNL or SET, which facilitates the positioning and operation of subsequent processes.

[0048] Step 4: Insert isolation protection and layered laser forming.

[0049] Step 4.1, Insert metal isolation plate 5: as shown Figure 4 As shown, for the first layer of FPC core board that needs to be cut, a metal isolation plate 5 of matching size is precisely inserted from the side into the gap in the glue-free window area between the first circuit structure layer and the layer below it. The function of this isolation plate is to block laser energy and protect the non-target layer below.

[0050] Step 4.2: Adjust the laser parameters and perform laser cutting on the first circuit structure layer along a predetermined path that differs from the common area. Because of the metal isolation plate 5 underneath, the laser can completely cut this layer without damaging the underlying layers.

[0051] Step 4.3, Layer-by-layer processing: Remove the metal separator 5 from under the first FPC core board and insert it between the second FPC core board and the next lower FPC core board. Repeat steps 4.1 and 4.2 to cut the second FPC core board using a separate external shape path. Continue in this manner until all circuit structure layers requiring a separate external shape have been processed.

[0052] The isolation plate can form a precise and effective physical barrier between the target layer and the lower layer at the moment of cutting, completely absorbing the scattered laser energy, thereby completely avoiding defects such as interlayer short circuits and dielectric damage, and ensuring the yield rate of layered irregular shape processing.

[0053] Step 5: Final shaping.

[0054] Remove all the insulating metal plates and perform necessary cleaning or micro-processing on the machined edges. At this point, the multilayer flexible circuit board has achieved differentiated design of the contours of each circuit structure layer in the target area, and the final product is as follows: Figure 5 As shown. In practical applications, further processing can be carried out on the formed product according to the specific application scenario.

[0055] This invention fundamentally changes the processing mode of "one-piece molding" of multilayer flexible circuit boards. Through the preliminary "selective glue removal" design, combined with the subsequent "insertion isolation and layer-by-layer cutting" process, it is the first time that, at the level of economical and reliable industrial production, different circuit structure layers can have completely independent external outlines within the same circuit board.

[0056] Based on the above processing method, the present invention also discloses a flexible circuit board with an independent shape layered board. The flexible circuit board includes at least two stacked FPC core boards. The at least two FPC core boards are provided with an adhesive area 3 and a glue-free window area 4. The FPC core boards are bonded to each other in the adhesive area 3 by an adhesive material. In the glue-free window area 4, there is no adhesive material between the at least two FPC core boards. The outer contours of the at least two FPC core boards in the glue-free window area 4 are different from each other.

[0057] Flexible circuit boards manufactured using the method of this invention can bring direct product-level benefits:

[0058] Improve space utilization: The shape of each layer can be staggered according to the actual height of the assembled components, achieving a more compact stacking in the Z-axis direction and reducing the overall volume of the module.

[0059] Optimize electrical performance: By designing independent, shielded boundary profiles for sensitive signal layers, or by providing a better reference plane for high-speed signals through shape isolation, signal crosstalk can be effectively reduced, and the integrity and stability of transmission can be improved.

[0060] Improved heat dissipation: The staggered layered structure can form micro air channels between the layers, which is conducive to heat dissipation.

[0061] The above description is merely an embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for processing a flexible circuit board with independently shaped layered panels, characterized in that, Includes the following steps: Step 1: Provide multiple FPC core boards and perform preprocessing; Multiple FPC core boards with completed inner layer circuitry are provided. Target areas that need to achieve independent shapes are predefined on the FPC core boards. The entire area of ​​the FPC core board includes a common area with a consistent shape and a target area with an independent shape. The target area with an independent shape refers to the area with different shapes between the FPC core boards. Treatment of interlayer adhesive material: The target area where the FPC core board needs to achieve an independent shape is predefined on the interlayer adhesive material of the FPC core board. Within the target area of ​​the independent shape, some or all of the adhesive material is removed. Multiple FPC core boards are stacked together using a treated interlayer adhesive material, resulting in glue-free window areas on the stacked FPC core boards. Step 2: Lamination and FPC main body fabrication; The stacked materials are pressed together to form a single multilayer board; standard subsequent processes are then performed on the pressed multilayer board to complete the FPC main body fabrication. Step 3: Preliminary cutting and pre-separation of layers; Cut along the outer perimeter of the board and the common area where all circuit structure layers have the same shape; Step 4: Insert isolation protection and layered laser forming; Step 4.1: Insert a metal isolation plate: For the first circuit structure layer that needs to be cut, insert a metal isolation plate of the same size into the glue-free gap between the first circuit structure layer and the layer below it from the side. Step 4.2: Adjust the laser parameters and perform laser cutting on the first circuit structure layer along a predetermined path that is different from the common area; Step 4.3, Layer-by-layer processing: Remove the metal isolation plate under the first layer and insert it between the second layer and the next layer that needs to be processed. Repeat steps 4.1 and 4.2 to cut the second layer with another independent shape path. Continue in this way until all circuit structure layers that require independent shapes have been processed. Step 5: Final shaping; remove the metal isolation plate and clean or micro-process the processed edges; the multilayer flexible circuit board has achieved differentiated design of the contours of each circuit structure layer in the target area.

2. The method for processing a flexible circuit board with an independently shaped layered board according to claim 1, characterized in that, In step 1, there are no vent holes in the glue-free window area.

3. The method for processing a flexible circuit board with an independently shaped layered board according to claim 1, characterized in that, In step 2, the FPC body fabrication includes drilling, hole metallization, applying an outer cover film, and surface treatment.

4. The method for processing a flexible circuit board with an independently shaped layered board according to claim 3, characterized in that, In step 2, the FPC body fabrication also includes the fabrication of the outer layer circuit pattern, which is carried out after the hole metallization and before the outer layer cover film is applied.

5. A method for processing a flexible circuit board with an independently shaped layered board according to claim 1, characterized in that, In step 3, the initial cutting is performed using die punching or laser cutting.

6. A flexible circuit board with independently shaped layered panels, characterized in that, The circuit board is processed using the method described in any one of claims 1-5. The flexible circuit board includes at least two stacked FPC core boards. The at least two FPC core boards are provided with an adhesive area and a glue-free window area. The FPC core boards are bonded to each other in the adhesive area by an adhesive material. In the glue-free window area, there is no adhesive material between at least two FPC core boards. The outer contours of at least two FPC core boards in the glue-free window area are different from each other.

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