A rigid-flex printed circuit board and its manufacturing method

Abstract

The present application provides a hard-flex board and a method for making the same, wherein the method for making the hard-flex board includes: providing a flexible substrate; laminating a layer of flexible resin-coated copper foil on the two opposite sides of the flexible substrate to obtain a soft board layer; wherein the flexible resin-coated copper foil includes a resin layer, an insulating layer and a copper foil layer in sequence, and the copper foil layer is arranged on the side away from the flexible substrate; pasting a peelable adhesive on the surface of the flexible resin-coated copper foil at the position to be opened; laminating a semi-cured sheet and a resin copper foil layer on the surface of the flexible resin-coated copper foil and the peelable adhesive in sequence to obtain a hard board layer; wherein the resin copper foil layer includes at least one insulating layer and two copper foil layers located on the opposite sides of the insulating layer; removing the hard board layer at the position to be opened by using the peelable adhesive to obtain a hard-flex board. By means of the above method, the production process is reduced and the cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of circuit board processing and manufacturing, and in particular to a rigid-flexible board and a manufacturing method thereof. Background Art

[0002] With the continuous development and popularization of PCB, the application of RF PCB is gradually increasing, such as in the fields of consumer electronics, new energy vehicles, etc. At present, PCB is developing towards light, thin, short and small, which puts higher requirements on the combination of soft and hard boards.

[0003] For ordinary multi-layer rigid-flex boards, the flexible board area needs to be covered with a cover film, which has a long processing flow and high cost, and is not conducive to the requirement of thinness. Summary of the invention

[0004] The present application provides a rigid-flexible board and a manufacturing method thereof, which solves the problems of long processing flow and high cost in the prior art.

[0005] To solve the above problems, the present application provides a method for manufacturing a hard-flex board, which comprises: providing a flexible substrate; laminating a layer of flexible resin-coated copper foil on two opposite sides of the flexible substrate to obtain a soft board layer; wherein the flexible resin-coated copper foil comprises a resin layer, an insulating layer and a copper foil layer in sequence, and the copper foil layer is arranged away from the side of the flexible substrate; pasting a peelable adhesive at a position to be opened on the surface of the flexible resin-coated copper foil; laminating a semi-cured sheet and a resin copper foil layer on the surfaces of the flexible resin-coated copper foil and the peelable adhesive in sequence to obtain a hard board layer; wherein the resin copper foil layer comprises at least one insulating layer and two copper foil layers located on opposite sides of the insulating layer; removing the hard board layer at the position to be opened by using the peelable adhesive to obtain the hard-flex board.

[0006] Among them, the soft board layer forms the soft board area of the hard-flex board, and the hard board layer and the soft board layer form the hard board area of the hard-flex board; after the step of using the peelable glue to remove the hard board layer at the position to be opened to obtain the hard-flex board, it also includes: laser ablation and window opening of the soft board area of the hard-flex board to expose part of the copper foil layer of the soft board layer to form connecting pads in the soft board area of the hard-flex board.

[0007] The flexible substrate includes a resin layer and copper foil layers located on opposite sides of the resin layer; the step of laser ablation and window opening of the soft board area of the hard-flex board includes: removing the flexible resin-coated copper foil on the surface of the soft board layer to expose the copper foil layer of the flexible substrate.

[0008] Wherein, the step of providing a flexible substrate further includes: making the surface of the copper foil layer on one side of the flexible substrate or the surfaces of the copper foil layers on two opposite sides into a circuit pattern.

[0009] Wherein, before the step of pasting the peelable adhesive at the position to be opened on the surface of the flexible resin-coated copper foil, the method includes: removing the copper foil layer at the position to be opened on the surface of the flexible resin-coated copper foil by using a graphic etching process.

[0010] Wherein, the position to be opened is located on the same side of the two opposite sides of the soft board layer, and the soft-hard combination board is a soft-hard combination board with a flying tail structure.

[0011] Wherein, the resin copper foil layer includes an insulating layer and two copper foil layers located on opposite sides of the insulating layer;

[0012] The step of sequentially pressing a semi-cured sheet and a resin copper foil layer on the surface of the flexible resin-coated copper foil and the strippable adhesive to obtain a hard board layer also includes: pressing a first layer of semi-cured sheet on the surface of the flexible resin-coated copper foil and the strippable adhesive; pressing a first layer of resin copper foil layer on the surface of the first layer of semi-cured sheet; pressing a second layer of semi-cured sheet on the surface of the resin copper foil layer; pressing a second layer of resin copper foil layer on the surface of the second layer of semi-cured sheet to form the hard board layer comprising at least four copper foil layers.

[0013] After the step of sequentially pressing a semi-cured sheet and a resin copper foil layer on the surface of the flexible resin-coated copper foil and the peelable adhesive to obtain a hard board layer, the process further includes: patterning the copper foil layer on the surface of the hard board layer to form an outer circuit copper layer; and making vias or through holes in the hard board area of the hard-flex board to electrically interconnect the outer circuit copper layer with the inner copper foil layer.

[0014] The present application also provides a hard-flex board, which includes a soft board area and a hard board area; the soft board area and the hard board area are connected by a flexible substrate; the soft board area includes a flexible resin-coated copper foil located on opposite sides of the flexible substrate; the hard board area includes a flexible resin-coated copper foil located on opposite sides of the flexible substrate and a prepreg and a resin copper foil layer located on the surface of the flexible resin-coated copper foil; wherein the flexible resin-coated copper foil includes a resin layer, an insulating layer and a copper foil layer in sequence, and the copper foil layer is arranged away from the side of the flexible substrate; the resin copper foil layer includes at least one insulating layer and two copper foil layers located on opposite sides of the insulating layer.

[0015] The flexible substrate includes a resin layer and copper foil layers located on two opposite sides of the resin layer; the soft board area is also provided with windows to expose the copper foil layers on the surface of the flexible substrate.

[0016] The beneficial effects of the present application are as follows: A flexible substrate is provided. On the opposite two surfaces of the flexible substrate, a flexible resin-coated copper foil is laminated on each surface to obtain a flexible board layer, and a peelable adhesive is pasted on the surface of the flexible resin-coated copper foil corresponding to the position where the cover needs to be opened; then, a prepreg and a resin copper foil layer are sequentially laminated on the surfaces of the flexible resin-coated copper foil and the peelable adhesive to obtain a rigid board layer; finally, the rigid board layer at the position where the cover needs to be opened is removed by using the peelable adhesive, thereby obtaining a rigid-flex board. By using a flexible resin-coated copper foil instead of a traditional cover film, not only the manufacturing process is reduced, but also the cost is lowered. At the same time, the board thickness can be reduced during the separate manufacturing of the flexible resin-coated copper foil, thereby reducing the board thickness of the rigid-flex board. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic flow chart of an embodiment of the manufacturing method of the rigid-flex board of the present application;

[0018] Figure 2 It is a schematic structural diagram of the first embodiment of the rigid-flex board of the present application;

[0019] Figure 3 It is a schematic structural diagram of the second embodiment of the rigid-flex board of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0021] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the", and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless clearly stated otherwise in the above text. "Plural" generally includes at least two, but does not exclude the case of including at least one.

[0022] It should be understood that the term " / and / " used herein is only a description of the associated relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this text generally represents an "or" relationship between the associated objects before and after. The terms "first", "second", etc. in the description and claims of the present application and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0023] It should be understood that the terms "include", "comprises" or any other variations used herein are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "includes..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0024] This application provides a method for manufacturing a rigid-flex board. For details, please refer to Figure 1 , Figure 1 FIG. 1 is a flow chart of an embodiment of a method for manufacturing a rigid-flexible board of the present application. Figure 1 As shown, the production method includes:

[0025] Step S11: providing a flexible substrate.

[0026] In this embodiment, the flexible substrate includes a resin layer and two copper foil layers. The copper foil layers are located on two opposite sides of the resin layer to form a flexible substrate including two copper foil layers. In other embodiments, the flexible substrate may also be composed of a copper foil layer. Copper foil is a metal material and is often used in boards such as PCB boards or circuit boards.

[0027] This step also includes: making the copper foil layer on one side of the flexible substrate or the copper foil layers on two opposite sides into a circuit pattern. By making the copper foil layer on the surface of the flexible substrate into a circuit pattern to form an inner circuit copper layer, it is also convenient to form a circuit pad after the subsequent soft board layer is opened, so as to form a circuit connection.

[0028] Step S12: laminating a layer of flexible resin-coated copper foil on two opposite sides of the flexible substrate to obtain a soft board layer.

[0029] The flexible resin-coated copper foil includes a resin layer, an insulating layer and a copper foil layer in sequence. The copper foil layer is arranged on the side away from the flexible substrate. That is, the resin layer, the insulating layer and the copper foil layer are arranged in sequence in the direction away from the flexible substrate.

[0030] The flexible resin-coated copper foil is a pre-processed semi-finished product, and in this embodiment, it can be directly applied to the processing technology of the rigid-flexible board. In this embodiment, the two sides of the flexible resin-coated copper foils provided with the resin layer are directly pressed onto the opposite two sides of the flexible substrate, so that the copper foil layer of the flexible resin-coated copper foil is arranged away from the side of the flexible substrate.

[0031] In one embodiment, the soft board layer includes a flexible substrate and flexible resin-coated copper foil layers located on two opposite sides of the flexible substrate.

[0032] In another embodiment, the flexible printed circuit (FPC) layer includes a flexible substrate, and a resin layer and an insulating layer located on opposite surface sides of the flexible substrate. In another embodiment, step S12 further includes: using a graphic etching process to remove the copper foil layer at the position corresponding to the to-be-opened cover on the surface of the flexible copper-clad laminate with resin coating, so as to form a flexible printed circuit (FPC) area with insulated surface. At the same time, it can also ensure that the surface of the board is flat after pasting the peelable adhesive in step S13, and avoid the unevenness or protrusion of the board surface caused by the excessive thickness of the peelable adhesive.

[0033] Step S13: Paste a peelable adhesive at the position corresponding to the to-be-opened cover on the surface of the flexible copper-clad laminate with resin coating.

[0034] Among them, the peelable adhesive can be completely removed without residue. The peelable adhesive is pasted at the position corresponding to the to-be-opened cover on the surface of the copper-clad laminate with resin coating, that is, corresponding to the subsequently formed flexible printed circuit (FPC) area, and the peelable adhesive is not pasted on the rigid board area.

[0035] Step S14: Press and laminate a prepreg and a copper-clad laminate layer on the surfaces of the flexible copper-clad laminate with resin coating and the peelable adhesive in sequence to obtain a rigid board layer.

[0036] A rigid board layer is fabricated on the surface of the flexible copper-clad laminate with resin coating, where the rigid board layer at least includes multiple insulating layers and copper foil layers formed alternately. That is, the copper-clad laminate layer at least includes one insulating layer and two copper foil layers located on opposite surface sides of the insulating layer.

[0037] In a specific embodiment, the copper-clad laminate layer includes one insulating layer and two copper foil layers located on opposite surface sides of the insulating layer. Step S14 specifically includes: pressing and laminating the first prepreg on the surfaces of the flexible copper-clad laminate with resin coating and the peelable adhesive, pressing and laminating the first copper-clad laminate layer on the surface of the first prepreg, pressing and laminating the second prepreg on the surface of the first copper foil layer, and pressing and laminating the second copper-clad laminate layer on the surface of the second prepreg, so as to form a rigid board layer including at least four copper foil layers. Among them, the material compositions of the first copper-clad laminate layer and the second copper-clad laminate layer are the same. The materials of the first prepreg and the second prepreg are the same. By analogy, multiple copper foil layers can be fabricated on the surface of the flexible printed circuit (FPC) layer according to the specific functional requirements of the rigid-flex printed circuit board. Among them, the copper-clad laminate layer can also be pre-designed and then pressed onto the surface of the flexible printed circuit (FPC) layer by a pressing method and separated by prepregs.

[0038] Among them, the prepreg is also called PP. In a specific embodiment, the insulating layer can be PP or insulating resin, and the material thereof is not specifically limited herein.

[0039] In another embodiment, the resin copper foil layer can also be directly made into the required number of copper layers. That is, the resin copper foil layer can include multiple insulating layers and copper foil layers arranged at intervals. Specifically, the resin copper foil layer sequentially includes a first copper foil layer, a first insulating layer, a second copper foil layer, a second insulating layer, and a third copper foil layer along the direction perpendicular to the board surface, thus forming a rigid board layer including two insulating layers and three copper foil layers. In other embodiments, a rigid board layer including three insulating layers and four copper foil layers can also be formed, which is not limited herein.

[0040] It should be noted that the rigid board layer is located on the opposite two side surfaces of the flexible board layer. The flexible board layer and the rigid board layers arranged on both sides of the flexible board layer form the rigid board area of the rigid-flex board, and the flexible board layer forms the flexible board area of the rigid-flex board.

[0041] After this step, it can also include: performing patterning on the copper foil layer on the surface of the rigid board layer to form an outer layer circuit copper foil layer; making vias or through holes in the rigid board area of the rigid-flex board to enable electrical interconnection between the outer layer circuit copper foil layer and the inner layer copper foil layer, and further enabling electrical interconnection between the circuit copper foil layers in the rigid board area and the circuit copper foil layers in the flexible board area. Among them, each copper foil layer of the rigid-flex board can be made into a circuit copper foil layer.

[0042] Step S15: Use a peelable adhesive to remove the rigid board layer at the position to be opened, obtaining a rigid-flex board.

[0043] This step specifically includes: using a milling process to process the rigid board layer at the position to be opened to expose the peelable adhesive layer, and then using the peelable adhesive to tear off the rigid board layer at the position to be opened, thereby obtaining a rigid-flex board.

[0044] After this step, it also includes: performing laser ablation windowing on the flexible board area of the rigid-flex board to expose the copper foil layer on the flexible substrate of the flexible board layer, thereby forming connection pads in the flexible board area to facilitate connection with external devices or welding components in the flexible board area. Compared with welding components in the rigid board area, welding components in the flexible board area can reduce the overall volume of the rigid-flex board. In a specific embodiment, one connection pad can be formed by windowing on one side surface of the flexible board layer, or two connection pads can be formed by windowing on the opposite two side surfaces of the flexible board layer, which is not limited herein.

[0045] In a preferred embodiment, the opening position is set on the same side of the opposite two sides of the flexible board layer, so that the rigid-flex board forms a flying tail structure, and further facilitates windowing in the flexible board area to form connection pads to connect to an external circuit. In other embodiments, the opening position can also be set at the middle position of the opposite two sides of the flexible board layer to form a left-right symmetric rigid-flex board.

[0046] The beneficial effects of this embodiment are as follows: a soft board layer is obtained by laminating a layer of flexible resin-coated copper foil on the surfaces of the two opposite sides of the flexible substrate, and a peelable adhesive is pasted on the surface of the flexible resin-coated copper foil at the position to be opened; then a semi-cured sheet and a resin copper foil layer are sequentially pressed on the surface of the flexible resin-coated copper foil and the peelable adhesive to obtain a hard board layer; finally, the hard board layer at the position to be opened is removed using the peelable adhesive, thereby obtaining a hard-flex board. Using a flexible resin-coated copper foil instead of a traditional covering film not only reduces the production process, but also reduces costs. At the same time, the board thickness can be reduced in the process of making a flexible resin-coated copper foil alone, thereby reducing the board thickness of the hard-flex board. In addition, the hard-flex board adopts a flying tail structure, which makes the precision of laser ablation window opening in the soft board area higher.

[0047] This application also provides a rigid-flex board. Figure 2 , Figure 2 This is a schematic diagram of the structure of the first embodiment of the rigid-flex board of this application. Figure 2 As shown, the rigid-flex board includes a flexible board area 21 and a rigid board area 22 .

[0048] The soft board area 21 and the hard board area 22 are connected via a flexible substrate 201 .

[0049] The flexible board area 21 includes a flexible substrate 201 and a flexible resin-coated copper foil 202 located on two opposite sides of the flexible substrate 201. The flexible resin-coated copper foil 202 includes a resin layer C, an insulating layer P and a copper foil layer T in sequence.

[0050] The hard board area 22 includes a flexible substrate 201, a flexible resin-coated copper foil 202 located on opposite sides of the flexible substrate 201, and a prepreg 203 and a resin copper foil layer 204 located on the surface of the flexible resin-coated copper foil 202. The resin copper foil layer 204 includes at least one insulating layer P and two copper foil layers T located on opposite sides of the insulating layer.

[0051] In a specific embodiment, the flexible substrate 201 includes a resin layer C and copper foil layers T located on opposite sides of the resin layer C, and the copper foil layer T of the flexible resin-coated copper foil 202 corresponding to the flexible board area is removed to expose the insulating layer. The flexible board area 21 is also provided with an opening 211 to expose the copper foil layer T on the surface of the flexible substrate 201 to form a connection pad.

[0052] In this embodiment, the rigid board area 22 is further provided with a via 221 , and a copper layer is plated on the side wall of the via 221 to connect the inner copper foil layer and the outer copper foil layer.

[0053] In this embodiment, the soft board area 21 is located on one side of the hard board area 22 to form a hard-flex board with a flying tail structure.

[0054] The beneficial effects of this embodiment are as follows: By providing openings in the flexible board area to expose the copper foil layer on the flexible substrate, connection pads are formed for electrical connection with an external circuit. Additionally, the rigid-flex board adopts a flying tail structure, enabling higher precision in laser ablation for windowing in the flexible board area.

[0055] In other embodiments, the flexible board area 21 can also be located between two rigid board areas 22.

[0056] For details, please refer to Figure 3 , Figure 3 which is a schematic structural diagram of the second embodiment of the rigid-flex board of the present application. As Figure 3 shown, the rigid-flex board includes a flexible board area 31 and a rigid board area 32.

[0057] Among them, the flexible board area 31 and the rigid board area 32 are connected by a flexible substrate 301.

[0058] The flexible board area 31 includes a resin layer C and an insulating layer P of the flexible resin-coated copper foil 302 located on the flexible substrate 301 and on both opposite sides of the flexible substrate 301. Among them, the flexible resin-coated copper foil 302 in the flexible board area 31 includes a resin layer C and an insulating layer P.

[0059] The rigid board area 32 includes the flexible substrate 301, the flexible resin-coated copper foil 302 on both opposite sides of the flexible substrate 301, and a prepreg 303 and a resin copper foil layer 304 on the surface of the flexible resin-coated copper foil 302. The flexible resin-coated copper foil 302 in the rigid board area 32 sequentially includes a resin layer C, an insulating layer P, and a copper foil layer T. Among them, the resin copper foil layer 304 further includes an insulating layer P and two copper foil layers T on both opposite sides of the insulating layer.

[0060] In a specific embodiment, the flexible substrate 301 includes a resin layer C and copper foil layers T on both opposite surfaces of the resin layer C.

[0061] Among them, the flexible board area 31 is also provided with an opening 311 to remove the resin layer C and the insulating layer P of the flexible resin-coated copper foil 302 to expose the copper foil layer T on the surface of the flexible substrate 301, forming a connection pad.

[0062] In this embodiment, the rigid board area 32 is also provided with a via 321, and a copper layer is plated on the side wall of the via 321 to connect the inner copper foil layer and the outer copper foil layer.

[0063] In this embodiment, the flexible board area 31 is located between two rigid board areas 32.

[0064] The beneficial effects of this embodiment are as follows: By providing openings in the flexible board area to expose the copper foil layer on the flexible substrate, connection pads are formed for electrical connection with an external circuit.

[0065] The above are only the embodiments of the present application, and do not limit the patent protection scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present application.

Claims

1. A manufacturing method of a rigid-flex printed circuit board, characterized in that, The method for manufacturing the rigid-flexible board comprises: Provided is a flexible substrate; the flexible substrate comprises a resin layer and copper foil layers located on two opposite sides of the resin layer; A layer of flexible resin-coated copper foil is laminated on two opposite sides of the flexible substrate to obtain a soft board layer; wherein the flexible resin-coated copper foil comprises a resin layer, an insulating layer and a copper foil layer in sequence, and the copper foil layer is arranged away from the side of the flexible substrate; Pasting a peelable adhesive on the surface of the flexible resin-coated copper foil at the position to be opened; A prepreg and a resin copper foil layer are sequentially pressed on the surface of the flexible resin-coated copper foil and the peelable adhesive to obtain a hard board layer; wherein the resin copper foil layer comprises at least one insulating layer and two copper foil layers located on opposite sides of the insulating layer; The hard board layer at the position where the cover is to be opened is processed by a milling process to expose the peelable adhesive; Using the peelable adhesive to tear off the hard board layer at the position to be opened, to obtain the hard-flex board; Laser ablation is performed on the soft board area of the hard-flex board to open windows, remove the flexible resin-coated copper foil on the surface of the soft board layer, and expose part of the copper foil layer of the soft board layer to form connection pads in the soft board area of the hard-flex board.

2. The manufacturing method of the rigid-flex printed circuit board according to claim 1, wherein The step of providing a flexible substrate further includes: The copper foil layer surface on one side of the flexible substrate or the copper foil layer surfaces on two opposite sides are made into a circuit pattern.

3. The manufacturing method of the rigid-flex printed circuit board according to claim 1, wherein, Before the step of pasting the peelable adhesive at the position to be opened on the surface of the flexible resin-coated copper foil, the method comprises: The copper foil layer at the position to be opened on the surface of the flexible resin-coated copper foil is removed by using a graphic etching process.

4. The manufacturing method of the rigid-flex printed circuit board according to claim 1, wherein, The position to be opened is located on the same side of the two opposite sides of the soft board layer, and the hard-soft board is a hard-soft board with a flying tail structure.

5. The manufacturing method of the rigid-flex printed circuit board according to claim 1, wherein, The resin copper foil layer includes an insulating layer and two copper foil layers located on opposite sides of the insulating layer; The step of sequentially pressing a prepreg and a resin copper foil layer on the surface of the flexible resin-coated copper foil and the peelable adhesive to obtain a hard board layer also includes: Laminating a first layer of prepreg on the surface of the flexible resin-coated copper foil and the peelable adhesive; Laminating a first layer of resin copper foil on the surface of the first layer of prepreg; Laminating a second layer of prepreg on the surface of the resin copper foil layer; A second layer of resin copper foil is laminated on the surface of the second prepreg to form the hard board layer comprising at least four copper foil layers.

6. The manufacturing method of the rigid-flex printed circuit board according to claim 1, wherein After the step of sequentially pressing a prepreg and a resin copper foil layer on the surface of the flexible resin-coated copper foil and the peelable adhesive to obtain a hard board layer, the method further includes: Patterning the copper foil layer on the surface of the hard board layer to form an outer circuit copper layer; A via hole or through hole is made in the hard board area of the soft-hard combination board to form an electrical interconnection between the outer copper layer and the inner copper foil layer.

7. A rigid-flex printed circuit board, characterized in that, The rigid-flex board includes a flexible board area and a rigid board area; The soft board area and the hard board area are connected via a flexible substrate; the flexible substrate comprises a resin layer and copper foil layers located on two opposite sides of the resin layer; The soft board area includes flexible resin-coated copper foils located on opposite sides of the flexible substrate; wherein the flexible resin-coated copper foil includes a resin layer and an insulating layer in the soft board area in sequence; the soft board area is also provided with a window in which a portion of the flexible resin-coated copper foil on the surface of the flexible substrate is removed to expose the copper foil layer on the surface of the flexible substrate; The hard board area includes flexible resin-coated copper foil located on opposite sides of the flexible substrate and a prepreg and a resin copper foil layer located on the surface of the flexible resin-coated copper foil; wherein the flexible resin-coated copper foil includes a resin layer, an insulating layer and a copper foil layer in sequence in the hard board area, and the copper foil layer is arranged on the side away from the flexible substrate; the resin copper foil layer includes at least one insulating layer and two copper foil layers located on opposite sides of the insulating layer.

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