Rigid-flex board and manufacturing method thereof

Abstract

The invention discloses a rigid-flex board and a manufacturing method thereof, the rigid-flex board comprises a flexible core board, a cover film and a shielding film, the flexible core board comprises a signal area and an edge area, at least one side surface of the flexible core board is provided with a signal line in the signal area, the cover film is arranged on the surface of the flexible core board, and the shielding film is arranged on the surface of the flexible core board. The signal line is located between the soft board core board and the covering film, the shielding film is arranged on the side, away from the signal line, of the covering film, the shielding film covers the signal area, and the shielding film comprises a metal layer. Therefore, interference of external signals on the rigid-flex board can be reduced, and bending of the rigid-flex board is facilitated. The circuit board is widely applied to the technical field of circuit boards.

Description

Technical Field

[0001] The present application relates to the technical field of circuit boards, and in particular to a rigid-flex board and a method for manufacturing the same. Background Art

[0002] During the production of rigid-flex PCBs, special structural designs are often required for signal lines to ensure that the multi-layer PCB meets signal transmission requirements. For example, to avoid dispersion issues during high-speed transmission, the signal lines need to be designed as stripline structures. To isolate external signal interference, a core board is often used as a signal shielding layer for the stripline structure. This increases the thickness of the PCB area, making it difficult for the rigid-flex PCB product to bend. Summary of the Invention

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a rigid-flex board and a manufacturing method thereof, which can reduce interference of external signals on the rigid-flex board while facilitating the bending of the rigid-flex board.

[0004] According to the first embodiment of the present application, a rigid-flex board includes:

[0005] A flexible board core board, the flexible board core board comprising a signal area and an edge area, and a signal line is provided on at least one side surface of the flexible board core board in the signal area;

[0006] A covering film is provided on the surface of the soft board core, and the signal line is located between the soft board core and the covering film;

[0007] A shielding film is provided on a side of the covering film away from the signal line, the shielding film covers the signal area, and the shielding film includes a metal layer.

[0008] The rigid-flex board according to the embodiment of the present application has at least the following beneficial effects: by sequentially stacking a covering film and a shielding film on the side of the flexible board core board where the signal line is provided, the covering film is used to insulate the flexible board core board from the shielding film, and by covering the signal area with the shielding film and utilizing the metal layer of the shielding film as a shielding layer, the metal layer can play a role in isolating the interference of external signals, thereby reducing the interference of external signals on the rigid-flex board, and facilitating the bending of the rigid-flex board. At the same time, by providing the shielding film to cover only the signal area of the flexible board core board, that is, partially covering the flexible board core board with the shielding film, the thickness of the edge area can be reduced, thereby facilitating the bending performance of the rigid-flex board and further facilitating the bending of the rigid-flex board.

[0009] According to some embodiments of the present application, the signal line is provided on one side of the flexible board core board, and a grounding circuit is provided on the other side of the flexible board core board. The flexible board core board is provided with a grounding hole running through the signal area, and the grounding hole is conductively connected to the metal layer and the grounding circuit.

[0010] According to some embodiments of the present application, the grounding hole is metallized by plugging the hole with copper paste to conduct the connection between the metal layer and the grounding line.

[0011] According to some embodiments of the present application, the flexible board core board is provided with a grounding pad in the signal area, the grounding pad is conductively connected to the grounding hole and the metal layer, and the covering film is provided with a window corresponding to the position of the grounding pad.

[0012] According to some embodiments of the present application, there are multiple grounding holes, and the multiple grounding holes form a grounding hole group on both sides of the signal line. The multiple grounding holes in the grounding hole group are arranged in sequence along the extension direction of the signal line. The spacing between two adjacent grounding holes in the grounding hole group is defined as S, and the electromagnetic wavelength of the circuit at the maximum operating frequency is λ, wherein λ / 20≤S≤λ / 10.

[0013] According to some embodiments of the present application, the shielding film includes a working portion and a positioning portion, the working portion corresponds to the signal area, the positioning portion is used for positioning when the shielding film is attached, and is removed after the shielding film is attached.

[0014] According to some embodiments of the present application, the working part includes a film layer, a metal layer, an insulating layer and a first carrier part stacked in sequence, the positioning part includes a second carrier part, the second carrier part is connected to the first carrier part, the number of the positioning parts is two, the working part is located between the two positioning parts, and the first carrier part and the second carrier part are removed after the shielding film is bonded.

[0015] According to some embodiments of the present application, the rigid-flex board is provided with a positioning angle line, and the positioning portion is used to align with the positioning angle line.

[0016] According to a second aspect of the present application, a method for manufacturing a rigid-flex PCB is provided for manufacturing the rigid-flex PCB as described in the first aspect. The method comprises:

[0017] Providing a flexible core board, wherein at least one side surface of the flexible core board is provided with a signal line in a signal area;

[0018] Laminating a covering film on the surface of the soft board core board;

[0019] A shielding film is attached to a side of the cover film away from the signal line corresponding to the signal area.

[0020] The method for manufacturing a rigid-flex board according to the embodiment of the present application has at least the following beneficial effects: it can reduce the interference of external signals on the rigid-flex board while facilitating the bending of the rigid-flex board.

[0021] According to some embodiments of the present application, the step of attaching a shielding film to the signal area on a side of the cover film away from the signal line includes:

[0022] A shielding film is provided, the shielding film including a working portion and positioning portions located on both sides of the working portion, the shielding film including an adhesive film layer, a metal layer, an insulating layer, and a carrier film stacked in sequence, the carrier film including a first carrier portion and a second carrier portion, the first carrier portion being connected to the second carrier portion, the first carrier portion corresponding to the working portion, the second carrier portion corresponding to the positioning portions, and the rigid-flex board being provided with positioning angle lines;

[0023] Cutting off the film layer, the metal layer and the insulating layer of the positioning portion, and aligning the first carrier portion with the positioning angle line so that the working portion corresponds to the signal area;

[0024] Pressing and curing the shielding film;

[0025] The carrier film is removed by peeling.

[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present application is further described below with reference to the accompanying drawings and embodiments, wherein:

[0028] Figure 1 A schematic diagram of the structure of a rigid-flex board disclosed in the related art;

[0029] Figure 2 A schematic diagram of the structure of a rigid-flex board disclosed in an embodiment of the present application;

[0030] Figure 3 A top view of the rigid-flex board disclosed in an embodiment of the present application;

[0031] Figure 4 A schematic structural diagram of the soft board area of the rigid-flex board disclosed in an embodiment of the present application;

[0032] Figure 5 A schematic diagram of the manufacturing process of a rigid-flex PCB disclosed in an embodiment of the present application;

[0033] Figure 6A schematic diagram of the manufacturing process of the grounding hole disclosed in the embodiment of the present application;

[0034] Figure 7 A schematic diagram of the lamination process of the shielding film disclosed in an embodiment of the present application;

[0035] Figure 8 A schematic diagram of the manufacturing process of the shielding film disclosed in the embodiment of this application;

[0036] Figure 9 Schematic diagram of the shielding film and the soft board core board disclosed in the embodiment of the present application;

[0037] Figure 10 This is a flow chart of the method for manufacturing a rigid-flex PCB disclosed in an embodiment of the present application.

[0038] Reference numerals:

[0039] 1. Rigid-flex PCB; 1a. Flex board area; 1b. Rigid board area; 11. Flex board core; 111. Signal area; 112. Edge area; 12. Cover film; 13. Shielding film; 13a. Working part; 13b. Positioning part; 131. Metal layer; 132. Adhesive film layer; 133. Insulation layer; 134. First carrier portion; 135. Second carrier portion; 136. Protective film; 14. Signal line; 15. Ground line; 16. Ground hole; 17. Ground pad; 18. Rigid board core; 19. Adhesive layer;

[0040] 2. Screen version. DETAILED DESCRIPTION

[0041] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0042] In the description of this application, it should be understood that if the terms "center", "middle", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0043] In the description of this application, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0044] In the description of this application, unless otherwise specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed, detachable, or integral connections; they can refer to mechanical or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0045] In the description of this application, if the reference terms "as an embodiment", "one embodiment", "some examples", "some embodiments", "illustrative embodiment", "example", "specific example", "some examples", etc. appear, it means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0046] In the process of manufacturing rigid-flex PCB, in order to make the multi-layer PCB meet the signal transmission requirements, it is usually necessary to make special structural design for the signal line. Figure 1 In the related art, in order to avoid the dispersion problem that occurs during high-speed transmission, the signal line 14 of the flexible and rigid combination board needs to be designed as a stripline structure. At the same time, in order to isolate the interference of external signals, a core board is usually used as the signal shielding layer of the stripline structure, so that the flexible and rigid combination board 1 includes at least two flexible board core boards 11, and the two flexible board core boards 11 are connected by an adhesive layer, which increases the overall thickness of the flexible board area and is inconvenient for bending the flexible and rigid combination board product.

[0047] Based on this, the present application provides a flexible and rigid combination board and a manufacturing method thereof, by sequentially stacking a covering film and a shielding film on one side of a flexible board core board where a signal line is provided, and utilizing the metal layer of the shielding film to achieve a shielding effect, compared with the design of adding an additional flexible board core board and an adhesive layer as a shielding layer on the flexible board core board, it can have a smaller thickness, and by arranging a shielding film to partially cover the signal area on the flexible board core board, the thickness of the non-signal area of the flexible board area (i.e., the edge area below) can be reduced, so as to solve the problem that the overall thickness of the flexible board area is large and it is inconvenient for the flexible and rigid combination board to bend.

[0048] The contents of this application are described in detail below in conjunction with specific embodiments. It should be noted that the following description is only for illustrative purposes and is not a specific limitation to this application.

[0049] Please also refer to Figures 2 to 4 In the first aspect, an embodiment of the present application provides a hard-flex board 1, comprising a soft board core board 11, a covering film 12 and a shielding film 13. The soft board core board 11 comprises a signal area 111 and an edge area 112. A signal line 14 is provided on the surface of at least one side of the soft board core board 11 in the signal area 111. The covering film 12 is arranged on the surface of the soft board core board 11. The signal line 14 is located between the soft board core board 11 and the covering film 12. The shielding film 13 is arranged on the side of the covering film 12 away from the signal line 14. The shielding film 13 covers the signal area 111. The shielding film 13 comprises a metal layer 131.

[0050] The rigid-flex board 1 provided in the embodiment of the present application is characterized by sequentially stacking a covering film 12 and a shielding film 13 on one side of a flexible core board 11 provided with a signal line 14. The covering film 12 insulates the flexible core board 11 from the shielding film 13. By covering the shielding film 13 in the signal area 111, the metal layer 131 of the shielding film 13 is utilized as a shielding layer, so that the metal layer 131 can isolate interference from external signals, thereby reducing interference from external signals on the rigid-flex board 1. Furthermore, compared to designs in which the flexible core board 11 and an adhesive layer are additionally added to the flexible core board 11 as a shielding layer, the rigid-flex board 1 can have a smaller thickness, thereby reducing the thickness of the flexible board area 1a and facilitating the bending of the rigid-flex board 1. Furthermore, by providing the shielding film 13 to cover only the signal area 111 of the flexible core board 11, that is, by partially covering the flexible core board 11 with the shielding film 13, the thickness of the edge area 112 can be reduced, thereby improving the bending performance of the rigid-flex board 1 and further facilitating the bending of the rigid-flex board 1.

[0051] Please combine Figures 4 to 6 In some embodiments, a signal line 14 is provided on one side of the flexible board core board 11, and a grounding line 15 is provided on the other side of the flexible board core board 11. A grounding hole 16 is provided through the signal area 111 of the flexible board core board 11, and the grounding hole 16 is conductively connected to the metal layer 131 of the shielding film 13 and the grounding line 15.

[0052] In this way, the grounding hole 16 is connected to the metal layer 131 of the shielding film 13 and the grounding line 15 to form a loop surrounding the signal line 14, so as to provide the signal line 14 with an effect similar to a sealed space, thereby helping to improve the shielding effect of external interference signals, further reduce the interference of external signals on the soft-hard combination board 1, and improve the reliability of the soft-hard combination board 1.

[0053] Optionally, the grounding hole 16 is filled with a conductive material, and the grounding hole 16 connects the metal layer 131 and the grounding line 15 through the conductive material. This ensures the metal content in the grounding hole 16, and compared to the method of providing the metal layer 131 on the inner wall of the via hole and filling the via hole with ink or resin, it is beneficial to improve the shielding effect and ensure the reliability of the flexible rigid board 1.

[0054] Optionally, considering that the via metallization in related technologies is mostly made by copper plating on the entire board followed by electroplating, which increases the thickness of the surface copper, thereby making the flexible board core board 11 have a larger thickness, affecting the bending performance of the flexible and rigid board 1, based on this, the conductive material is copper paste, and the grounding hole 16 is plugged with copper paste to achieve via metallization, so as to connect the metal layer 131 and the grounding line 15.

[0055] In this way, the copper paste plugging process is used instead of the copper deposition and electroplating process, which can simplify the production process of the grounding hole 16 and reduce production costs. At the same time, since there is no need to deposit copper and electroplate the entire board, the thickness of the surface copper will not increase during the production of the grounding hole 16, which is conducive to reducing the thickness of the flexible board core board 11, so that the flexible and rigid board 1 has better bending performance. In addition, in order to achieve the best loss performance, the flexible and rigid board 1 currently usually uses polytetrafluoroethylene material to make the substrate. This material requires strict control of the electroplating parameters during electroplating, otherwise it is easy to have poor copper hole connection. The embodiment of the present application directly uses copper paste plugging to make metalized vias, which does not require the control of electroplating parameters, has better material compatibility, is less difficult to make, and is conducive to reducing manufacturing costs.

[0056] It should be noted that since the function of the grounding hole 16 in the rigid-flex board 1 is to shield interference signals and there is no need for reliability testing, the embodiment of the present application adopts a copper paste plugging method to achieve via metallization. When making the grounding hole 16, the copper paste is first filled into the grounding hole 16 by screen printing with a screen 2 and then baked. The board is then ground to remove the copper paste overflowing near the grounding hole 16, thereby completing the via metallization. In this way, the reliability of the rigid-flex board 1 is ensured, the production process of the grounding hole 16 is simplified, and the production cycle of the rigid-flex board 1 is shortened.

[0057] It can be understood that in other embodiments, the conductive material may also be an aluminum sheet.

[0058] Optionally, considering that the covering film 12 is an insulating material layer, the grounding hole 16 is connected to the shielding film 13 through the covering film 12, and the shielding effect is poor. Based on this, the covering film 12 is provided with a window at the position of the grounding hole 16 so that the copper paste in the grounding hole 16 can be connected to the shielding film 13 and the grounding line 15 to enclose and form a sealed loop to ensure the shielding effect.

[0059] Optionally, considering that the grounding hole 16 is made by the copper paste plugging process, there is a risk of incomplete plugging, resulting in a depression at the position where the plugging is incomplete, and the shielding film 13 is directly attached to the depressed position, which easily causes the shielding film 13 to be disconnected from the copper paste, affecting the shielding effect. Based on this, the flexible board core board 11 is provided with a grounding pad 17 in the signal area 111, and the grounding pad 17 is conductively connected to the grounding hole 16 and the metal layer 131, and the covering film 12 is provided with a window at the position corresponding to the grounding pad 17 (see Figure 4 ).

[0060] In this way, the grounding pad 17 can pass through the covering film 12 and directly contact the shielding film 13, and the grounding pad 17 ensures that the copper paste in the grounding hole 16 is conductively connected to the metal layer 131 of the shielding film 13, so that the shielding film 13, the grounding pad 17, the copper paste in the grounding hole 16 and the grounding line 15 can form a shielding loop surrounding the signal line 14, thereby reducing the influence of external interference signals on the signal line 14 and ensuring the reliability of the soft-hard combination board 1.

[0061] Optionally, considering that the larger the copper paste contact area between the pad and the grounding hole 16, the smaller the grounding resistance, based on this, the area of the pad can be greater than or equal to 0.8mm*0.8mm, thereby ensuring the copper paste contact area between the pad and the grounding hole 16 and ensuring the shielding effect.

[0062] It is understandable that in other embodiments, the ground pad 17 may be replaced by other conductive metals, such as copper or tin.

[0063] Please combine Figure 7 In some embodiments, there are multiple grounding holes 16, each of which forms a grounding hole group on both sides of the signal line 14. The multiple grounding holes 16 in the grounding hole group are sequentially spaced along the extension direction of the signal line 14. This can further reduce the interference of electromagnetic radiation and improve the shielding effect against external interference signals.

[0064] Optionally, considering that the principle of metallized hole shielding is mainly to use the reflection and absorption of electromagnetic waves by metal conductors, when electromagnetic waves contact metal holes, reflection will occur, most of the electromagnetic wave energy will be reflected back to the original direction, and a small amount of electromagnetic wave energy will be absorbed by the metal holes. Based on this, the spacing between two adjacent grounding holes 16 in the grounding hole group is defined as S (see Figure 3), the electromagnetic wavelength of the circuit at the maximum operating frequency is λ, where λ / 20≤S≤λ / 10.

[0065] By limiting the spacing S between adjacent grounding holes 16 to no more than 1 / 10 of the electromagnetic wavelength λ at the circuit's maximum operating frequency, continuous signal shielding effectiveness can be ensured. When S > λ / 10, the spacing between adjacent grounding holes 16 is too large, allowing some electromagnetic waves to pass through between the two grounding holes 16, affecting the shielding effect. When S < λ / 20, the spacing between adjacent grounding holes 16 is too small, making it difficult to manufacture the grounding holes.

[0066] Optionally, considering the convenience of drilling and the shielding effect, the diameter of the grounding hole 16 is R, 10mi≤R≤20mil, so as to facilitate the processing of the grounding hole and ensure the shielding effect.

[0067] Please refer again Figure 3 , combined with Figures 7 to 9 In some embodiments, the shielding film 13 includes a working portion 13a and a positioning portion 13b. The working portion 13a corresponds to the signal area 111, and the positioning portion 13b is used to position the shielding film 13 during lamination and is removed after the shielding film 13 is attached. This facilitates the positioning and attachment of the shielding film 13 while ensuring that the shielding film 13 is partially attached to the signal area 111 of the flexible core board 11, thereby reducing the thickness of the edge area 112 and facilitating the bending of the rigid-flex board 1.

[0068] Optionally, the working part 13a includes a film layer 132, a metal layer 131, an insulating layer 133 and a first carrier part 134 stacked in sequence, the positioning part 13b includes a second carrier part 135, the second carrier part 135 is connected to the first carrier part 134, the number of positioning parts 13b is two, the working part 13a is located between the two positioning parts 13b, and the first carrier part 134 and the second carrier part 135 are removed after the shielding film 13 is bonded.

[0069] In this way, by setting the positioning portion 13b to have only the second carrier portion 135, and using the first carrier portion 134 to drive the second carrier portion 135 to move and position, the working portion 13a can be positioned relative to the soft board core board 11 through the first carrier portion 134 during the bonding process, and the first carrier portion 134 and the second carrier portion 135 are peeled off after the bonding is completed, so that after the bonding is completed, the shielding film 13 only retains the film layer 132, the metal layer 131 and the insulating layer 133 in the signal area 111, wherein the film layer 132 is used to be glued and fixed with the covering film 12, the metal layer 131 is used to shield and isolate external interference signals, and the insulating layer 133 plays an insulating role, that is, the shielding film 13 only retains the necessary structure (the adhesive film layer 132 covering the signal area 111, the metal layer 131 and the insulating layer 133) after the bonding is completed, so as to help reduce the thickness of the flexible and rigid board 1 in the signal area 111 and the thickness of the non-signal area (that is, the edge area 112), thereby improving the bending performance of the flexible and rigid board 1 and facilitating the bending of the flexible and rigid board 1.

[0070] It should be noted that, as previously mentioned, a window is provided in the cover film 12 corresponding to the position of the grounding pad 17, so that the grounding pad 17 can pass through the cover film 12 and directly contact the shielding film 13. After the working portion 13a of the shielding film 13 is attached to the cover film 12, the adhesive layer 132 of the shielding film 13 is located between the metal layer 131 and the cover film 12. In one embodiment, the adhesive layer 132 contains conductive particles, and the grounding via 16 is conductively connected to the metal layer 131 through the grounding pad 17 and the adhesive layer 132, thereby achieving a metal shielding effect. In another embodiment, the adhesive layer 132 does not contain conductive particles, but when the shielding film 13 is pressed together, the metal layer 131 can pierce the adhesive layer 132 to connect to the grounding pad 17, so that the grounding via 16 is conductively connected to the metal layer 131 through the grounding pad 17.

[0071] Optionally, the rigid-flex board 1 is provided with a positioning angle line, and the second carrier portion 135 of the positioning portion 13b is used to align with the positioning angle line. Alignment of the positioning angle line and the second carrier portion 135 allows the shielding film 13 to be accurately attached to the flexible board core 11 via the positioning portion 13b, thereby facilitating the positioning and attachment of the shielding film 13 and ensuring the shielding effect of the shielding film 13 on the signal area 111.

[0072] Optionally, the positioning angle line can be a silk-screen mark on the rigid-flexible board 1, or the positioning angle line can be a mark formed on the rigid-flexible board 1 using a signal pen, a carving knife, etc., so as to ensure that the positioning angle line has little effect on the thickness of the flexible board core board 11, thereby ensuring the bending performance of the rigid-flexible board 1.

[0073] It is understandable that in other embodiments, the positioning angle line can also be replaced by a slot or a step.

[0074] Optionally, in some embodiments, the shielding film 13 further includes a protective film 136, which is disposed on the side of the adhesive film layer 132 away from the metal layer 131. The protective film 136 is used to protect the shielding film 13 during transportation and storage and ensure the adhesion of the adhesive film layer 132. Before the shielding film 13 is aligned and bonded to the flexible core board 11, the protective film 136 must be peeled off and removed to allow the adhesive film layer 132 to be pre-fixed and bonded to the cover film 12.

[0075] Please combine Figure 2 and Figure 3 In some embodiments, the rigid-flex board 1 further includes a rigid board core 18 and an adhesive layer 19. The rigid board core 18 is connected to the flexible board core 11 by laminating the adhesive layer. The rigid-flex board 1 includes a flexible board area 1a and a rigid board area 1b located on both sides of the flexible board area 1a. The rigid board core 18 is arranged in the rigid board area 1b. The signal area 111 of the flexible board core 11 is located in the flexible board area 1a. The covering film 12 is attached to the flexible board area 1a, and the shielding film 13 is attached to the signal area 111.

[0076] In this way, the hard board area 1b is not bonded with the covering film 12 and the shielding film 13. Compared with the design of adding the soft board core board 11 and the adhesive layer as the shielding layer on the soft board core board 11, the hard board area 1b can have a smaller thickness, so that the thickness of the soft-rigid combination board 1 is smaller, which is conducive to reducing costs and reducing the volume of the soft-rigid combination board 1.

[0077] Please refer to Figure 10 , combined with Figures 2 to 9 In a second aspect, an embodiment of the present application discloses a method for manufacturing a rigid-flex board 1, which is used to manufacture the rigid-flex board 1 as described in the first aspect above. The method for manufacturing the rigid-flex board 1 includes:

[0078] S100 , providing a flexible core board 11 , wherein a signal line 14 is provided in a signal area 111 on at least one side surface of the flexible core board 11 .

[0079] S200 , laminating a cover film 12 on the surface of the soft board core board 11 .

[0080] S300 , attaching the shielding film 13 to the signal area 111 on the side of the cover film 12 away from the signal line 14 .

[0081] Thus, by sequentially stacking a covering film 12 and a shielding film 13 on the side of the flexible core board 11 where the signal line 14 is provided, the covering film 12 insulates the flexible core board 11 from the shielding film 13. By covering the shielding film 13 on the signal area 111, the metal layer 131 of the shielding film 13 is utilized as a shielding layer, so that the metal layer 131 can isolate interference from external signals, thereby reducing interference of external signals on the rigid-flex board 1. Moreover, compared to the design of adding the flexible core board 11 and the adhesive layer as a shielding layer to the flexible core board 11, the thickness can be smaller, thereby reducing the thickness of the flexible board area 1a and facilitating the bending of the rigid-flex board 1. At the same time, by providing the shielding film 13 to cover only the signal area 111 of the flexible core board 11, that is, partially covering the flexible core board 11 with the shielding film 13, the thickness of the edge area 112 can be reduced, thereby facilitating the bending of the rigid-flex board 1 by improving the bending performance of the rigid-flex board 1 and further facilitating the bending of the rigid-flex board 1.

[0082] It can be understood that since the manufacturing method of the soft-rigid combination board 1 is used to manufacture the soft-rigid combination board 1 as described in the first aspect above, the manufacturing method of the soft-rigid combination board 1 provided in the embodiment of the present application also has the beneficial effects of the soft-rigid combination board 1 described in the first aspect above, and will not be repeated here.

[0083] In some embodiments, the above step S100 specifically includes the following steps:

[0084] S110 , providing a flexible core board 11 , wherein two opposite sides of the flexible core board 11 are respectively provided with copper layers.

[0085] S120 , drilling grounding holes 16 in the flexible board core board 11 , where the grounding holes 16 penetrate the copper layers on both sides of the flexible board core board 11 .

[0086] S130 , plugging the grounding hole 16 by using a copper paste plugging process.

[0087] Thus, using the copper paste plugging process to plug the grounding hole 16 can simplify the production process of the grounding hole 16 and reduce production costs, compared to using copper deposition and electroplating processes to metallize the grounding hole 16. At the same time, since there is no need to perform copper deposition and electroplating on the entire board, the thickness of the surface copper does not increase during the production of the grounding hole 16, which is conducive to reducing the thickness of the flexible board core board 11, making the flexible and rigid-flexible board 1 have better bending performance. In addition, using the copper paste plugging process to achieve metallization can increase the metal content in the grounding hole 16, thereby improving the shielding effect, compared to the method of providing a metal layer 131 on the inner wall of the via hole and filling the via hole with ink or resin. In addition, it can also improve material compatibility and reduce the difficulty and manufacturing cost of production.

[0088] Optionally, the above step S130 specifically includes the following steps:

[0089] S131 , filling the grounding hole 16 with copper paste through screen printing process 2 .

[0090] S132, baking the soft core board 11.

[0091] S133 , grinding the flexible core board 11 to remove the copper paste overflowing from the vicinity of the grounding hole 16 .

[0092] This completes the copper paste plugging process, facilitating conductive connection between the copper paste in the grounding hole 16 and the copper layers on both sides of the flexible core board 11. This facilitates the copper paste in the grounding hole 16 to connect with the metal layer 131 of the shielding film 13 and the grounding line 15 in subsequent steps, forming a shielding loop surrounding the signal line 14 and improving the shielding effect against external interference signals. Furthermore, the via metallization process of "filling the grounding hole 16 with copper paste using screen printing 2 → baking the board → grinding the board" can simplify the production process of the grounding hole 16 and help shorten the production cycle of the rigid-flex board 1.

[0093] S140 , performing exposure and etching processing on the copper layer of the flexible circuit board to obtain the signal line 14 and the ground line 15 .

[0094] At this time, the copper paste in the ground hole 16 is conductively connected to the signal line 14 and the ground line 15 .

[0095] In some embodiments, the above step S300 specifically includes the following steps:

[0096] S310. Provide a shielding film 13. The shielding film 13 includes a working part 13a and positioning parts 13b located on both sides of the working part 13a. The shielding film 13 includes a glue film layer 132, a metal layer 131, an insulating layer 133 and a carrier film stacked in sequence. The carrier film includes a first carrier part 134 and a second carrier part 135. The first carrier part 134 is connected to the second carrier part 135. The first carrier part 134 corresponds to the working part 13a, and the second carrier part 135 corresponds to the positioning part 13b. The soft-hard combination board 1 is provided with a positioning angle line on the side close to the signal line 14.

[0097] The positioning portion 13b is aligned with the positioning angle line to facilitate the positioning and fitting of the shielding membrane 13. At the same time, the positioning angle line is used as a positioning mark to reduce the influence of the positioning angle line on the thickness of the soft board core board 11, so as to ensure the bending performance of the soft-rigid combination board 1.

[0098] It should be noted that in some embodiments, the shielding film 13 further includes a protective film 136. The protective film 136 is disposed on the side of the adhesive film layer 132 away from the metal layer 131. The protective film 136 is used to protect the shielding film 13 during transportation and storage and ensure the adhesion of the adhesive film layer 132. Before the shielding film 13 is aligned and bonded to the flexible core board 11, the protective film 136 must be peeled off and removed to allow the adhesive film layer 132 to be pre-fixed and bonded to the cover film 12.

[0099] S320 , removing the adhesive film 132 , the metal layer 131 and the insulating layer 133 of the positioning portion 13 b , and aligning the first carrier portion 134 with the positioning angle line so that the working portion 13 a corresponds to the signal area 111 .

[0100] By cutting off the adhesive film layer 132, the metal layer 131 and the insulating layer 133 of the positioning part 13b, the positioning part 13b only retains the second carrier part 135. On the one hand, the first carrier part 134 can be used to drive the second carrier part 135 to move and position, so that the working part 13a can be positioned relative to the soft-rigid combination board 1 through the first carrier part 134 during the bonding process, so as to facilitate the positioning and bonding of the shielding film 13. On the other hand, it is convenient to remove the positioning part 13b in subsequent steps, so that the shielding film 13 only retains the working part 13a covering the signal area 111.

[0101] S330 , pressing and curing the shielding film 13 .

[0102] S340, peeling and removing the carrier film.

[0103] As a result, the shielding film 13 only retains the working part 13a covering the signal area 111, and the working part 13a only has the adhesive film layer 132, the metal layer 131 and the insulating layer 133, wherein the adhesive film layer 132 is used to bond and fix with the covering film 12, the metal layer 131 is used to shield and isolate external interference signals, and the insulating layer 133 plays an insulating role, that is, the shielding film 13 only retains the necessary structure (the adhesive film layer 132, the metal layer 131 and the insulating layer 133 covering the signal area 111) after the bonding is completed, so as to help reduce the thickness of the flexible and rigid board 1 in the signal area 111 and the thickness of the non-signal area (that is, the edge area 112), thereby improving the bending performance of the flexible and rigid board 1 and facilitating the bending of the flexible and rigid board 1.

[0104] It can be seen that the rigid-flexible board 1 prepared by the manufacturing method of the rigid-flexible board 1 of the embodiment of the present application has only one flexible board core board 11, and the flexible board area 1a can realize the stripline structure and the shielding effect against external interference signals, and the rigid-flexible board 1 has the advantage of reducing the number of layers of the flexible board area 1a. In addition, the thickness of the flexible board area 1a is reduced by locally bonding the shielding film 13, and the surface copper thickness is reduced by the copper paste plugging process, which can reduce the thickness of the soft board area 1a of the rigid-flexible board 1, thereby making the soft board area 1a of the rigid-flexible board 1 have more excellent bending performance.

[0105] The embodiments of the present application have been described in detail above with reference to the accompanying drawings. However, the present application is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present application. In addition, the embodiments of the present application and the features of the embodiments can be combined with each other unless there is a conflict.

Claims

1. A rigid-flex board, characterized in that: include: A flexible board core board, the flexible board core board comprising a signal area and an edge area, and a signal line is provided on at least one side surface of the flexible board core board in the signal area; A covering film is provided on the surface of the soft board core, and the signal line is located between the soft board core and the covering film; A shielding film is provided on a side of the covering film away from the signal line, the shielding film covers the signal area, and the shielding film includes a metal layer.

2. The rigid-flex board according to claim 1, characterized in that: The signal line is provided on one side of the flexible board core board, and a grounding circuit is provided on the other side of the flexible board core board. The flexible board core board is provided with a grounding hole running through the signal area, and the grounding hole is conductively connected to the metal layer and the grounding circuit.

3. The rigid-flex board according to claim 2, characterized in that: The grounding hole is plugged with copper paste to achieve via metallization, so as to conduct the connection between the metal layer and the grounding line.

4. The rigid-flex board according to claim 2, characterized in that: The flexible board core is provided with a ground pad in the signal area, the ground pad is conductively connected to the ground hole and the metal layer, and the covering film is provided with a window corresponding to the position of the ground pad.

5. The rigid-flex board according to claim 2, characterized in that: There are multiple grounding holes, and the multiple grounding holes form a grounding hole group on both sides of the signal line. The multiple grounding holes in the grounding hole group are arranged in sequence along the extension direction of the signal line. The spacing between two adjacent grounding holes in the grounding hole group is defined as S, and the electromagnetic wavelength of the circuit at the maximum operating frequency is λ, where λ / 20≤S≤λ / 10.

6. The rigid-flex board according to claim 1, characterized in that: The shielding film includes a working portion and a positioning portion, the working portion corresponds to the signal area, the positioning portion is used for positioning when the shielding film is attached, and is removed after the shielding film is attached.

7. The rigid-flex board according to claim 6, characterized in that: The working part includes a film layer, a metal layer, an insulating layer and a first carrier part stacked in sequence, the positioning part includes a second carrier part, the second carrier part is connected to the first carrier part, the number of the positioning parts is two, the working part is located between the two positioning parts, and the first carrier part and the second carrier part are removed after the shielding film is bonded.

8. The rigid-flex board according to claim 6, characterized in that: The rigid-flex board is provided with a positioning angle line, and the positioning portion is used to align with the positioning angle line.

9. A method for manufacturing a rigid-flex board, characterized in that: Used to manufacture the rigid-flex board according to any one of claims 1 to 8, the manufacturing method comprising: Providing a flexible core board, wherein at least one side surface of the flexible core board is provided with a signal line in a signal area; Laminating a covering film on the surface of the soft board core board; A shielding film is attached to a side of the cover film away from the signal line corresponding to the signal area.

10. The method for manufacturing a rigid-flex PCB according to claim 9, wherein: The step of attaching a shielding film to the signal area on a side of the cover film away from the signal line includes: A shielding film is provided, the shielding film including a working portion and positioning portions located on both sides of the working portion, the shielding film including an adhesive film layer, a metal layer, an insulating layer, and a carrier film stacked in sequence, the carrier film including a first carrier portion and a second carrier portion, the first carrier portion being connected to the second carrier portion, the first carrier portion corresponding to the working portion, the second carrier portion corresponding to the positioning portions, and the rigid-flex board being provided with positioning angle lines; Cutting off the film layer, the metal layer and the insulating layer of the positioning portion, and aligning the first carrier portion with the positioning angle line so that the working portion corresponds to the signal area; Pressing and curing the shielding film; The carrier film is removed by peeling.

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