Method for manufacturing rigid-flex board and rigid-flex board

Abstract

The present application relates to the technical field of rigid-flex PCB production and manufacturing, and provides a rigid-flex PCB manufacturing method and a rigid-flex PCB. The rigid-flex PCB manufacturing method includes: providing an FPC board, the FPC board having a first copper layer, the first copper layer being provided with a first solder pad PAD; attaching and pressing a first cover film on the first copper layer, the first cover film being provided with a first window hole, the first window hole exposing the first solder pad PAD; printing a first solder mask ink on the first solder pad PAD; pressing a first PCB board on the first copper layer; and removing a portion of the first PCB board to expose the first solder mask ink. Applying the rigid-flex PCB manufacturing method provided in the embodiment of the present application can ensure that the first solder mask ink can effectively cover the first solder pad PAD.

Description

Technical Field

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

[0002] A rigid-flex board is a circuit board that combines a flexible circuit board (FPC) and a rigid circuit board (PCB) through lamination, through-holes, etc., according to relevant process requirements. The result is a circuit board that has both the flexibility of a flexible circuit board and the flatness and rigidity of a rigid circuit board.

[0003] Generally, the structure of a rigid-flex board uses a PCB as the outer hard board layer and an FPC as the inner soft board layer. The PCB and FPC are then stacked and pressed together using a high-temperature and high-pressure process. Since some soft board areas need to maintain their original soft properties and do not require a hard board layer, the PCB cover of this part, which serves as the hard board layer, needs to be removed.

[0004] High-precision electronic components are small in size, so to save layout space, they are usually designed on the FPC in the cover area for easy assembly and bending. Due to the limitations of the equipment process capabilities of the cover film window, the printing solder mask ink process is used for the locations with smaller pads PAD.

[0005] In the traditional method of manufacturing flexible and rigid boards, the FPC layer of the rigid board is often removed first, and then solder mask ink is printed in the removed area to cover the pads PAD. Due to the depth of the removed area, the solder mask ink cannot well cover the pads PAD of the FPC located inside. Summary of the Invention

[0006] The present application provides a method for manufacturing a rigid-flex board and a rigid-flex board to ensure that solder mask ink can better cover the pads PAD of the internal FPC.

[0007] In a first aspect, an embodiment of the present application provides a method for manufacturing a rigid-flex PCB, comprising:

[0008] Providing an FPC board, the FPC board having a first copper layer, and a first pad PAD is provided on the first copper layer;

[0009] Attaching and pressing a first cover film on the first copper layer, wherein the first cover film is provided with a first window hole, and the first window hole exposes the first pad PAD;

[0010] Printing a first solder resist ink on the first pad PAD;

[0011] Laminating a first PCB board on the first copper layer;

[0012] A portion of the first PCB is removed to expose the first solder mask ink.

[0013] In some embodiments, the FPC board further has a second copper layer opposite to the first copper layer, and a second pad PAD is provided on the second copper layer; after providing an FPC board, the method for manufacturing a rigid-flex board further includes:

[0014] Attaching and pressing a second cover film on the second copper layer, wherein the second cover film is provided with a second window hole, and the second window hole exposes the second pad PAD;

[0015] Printing a second solder resist ink on the second pad PAD;

[0016] Laminating a second PCB board on the second copper layer;

[0017] A portion of the second PCB is removed to expose the second solder mask ink.

[0018] In some embodiments, the first PCB board is provided with a third copper layer, and before the first PCB board is pressed onto the first copper layer, a first avoidance groove is processed on the third copper layer; pressing the first PCB board onto the first copper layer includes:

[0019] placing a first prepreg on the first copper layer, wherein the first prepreg is provided with a first avoidance hole, and the first avoidance hole exposes the first solder mask ink;

[0020] Placing the first PCB board on the side of the first prepreg facing away from the FPC board, and laminating the third copper layer to the first prepreg;

[0021] The first PCB board, the first prepreg and the FPC board are pressed together so that the hole wall of the first avoidance hole, the first avoidance groove and the first solder mask ink are combined to form a first cavity.

[0022] In some embodiments, the projection of the first avoidance hole on the third copper layer is located in the first avoidance groove, and the distance between the projection of the first avoidance hole on the third copper layer and the side groove wall of the first avoidance groove is 0.4mm-0.6mm.

[0023] In some embodiments, the first avoidance groove is processed on the third copper layer by exposure, development, and etching.

[0024] In some embodiments, removing a portion of the first PCB board and exposing the first solder mask ink includes: removing a portion of the first PCB board located at the bottom of the first avoidance groove by laser peeling and exposing the first solder mask ink.

[0025] In some embodiments, before printing the first solder mask ink on the first pad PAD, the first copper layer in the area where the first pad PAD is located is roughened.

[0026] In some embodiments, before printing the first solder mask ink on the first pad PAD, the first covering film constituting the hole wall of the first window hole is roughened.

[0027] In some embodiments, after the first PCB is laminated on the first copper layer, a third solder mask ink is printed on the side of the first PCB facing away from the FPC board, and then a portion of the first PCB is removed to expose the first solder mask ink.

[0028] In a second aspect, an embodiment of the present application provides a rigid-flex board, which is manufactured by the rigid-flex board manufacturing method as described in the first aspect.

[0029] The method for manufacturing a rigid-flex board provided in an embodiment of the present application has the beneficial effect of first printing a first solder mask ink on a first pad PAD of a first copper layer, then laminating a first PCB board on the first copper layer, and finally removing a portion of the first PCB board to expose the first solder mask ink, thereby ensuring that the first solder mask ink can better cover the first pad PAD.

[0030] The beneficial effects of the rigid-flex board provided in this application compared to the prior art, as well as the beneficial effects of the rigid-flex board manufacturing method provided in this application compared to the prior art, will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 This is a flow chart of a method for manufacturing a rigid-flex PCB in one embodiment of the present application;

[0033] Figure 2 This is a schematic diagram of the structure of a rigid-flex board in one of the embodiments of the present application;

[0034] Figure 3 It is a structural diagram of a rigid-flex board in another embodiment of the present application.

[0035] The meanings of the marks in the figure are:

[0036] 10. FPC board; 11. First copper layer; 12. Second copper layer; 13. First solder pad PAD; 14. Second solder pad PAD; 20. First covering film; 21. First window hole; 30. First solder mask ink; 40. First PCB board; 41. Third copper layer; 42. First avoidance groove; 50. Second covering film; 51. Second window hole; 60. Second solder mask ink; 70. Second PCB board; 71. Fourth copper layer; 72. Second avoidance groove; 80. First prepreg; 801. First avoidance hole; 81. Second prepreg; 811. Second avoidance hole; 90. Third solder mask ink; 91. Fourth solder mask ink. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0038] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0040] References to "one embodiment," "some embodiments," or "an embodiment" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present invention. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. Furthermore, in one or more embodiments, particular features, structures, or characteristics may be combined in any suitable manner.

[0041] In order to illustrate the technical solution of the present application, the following description is given with reference to specific drawings and embodiments.

[0042] Please refer to Figure 1 and Figure 2 In a first aspect, an embodiment of the present application provides a method for manufacturing a rigid-flex PCB, comprising:

[0043] S100 : providing an FPC board 10 , wherein the FPC board 10 has a first copper layer 11 , and a first pad PAD 13 is provided on the first copper layer 11 .

[0044] Specifically, the FPC board 10 may be a circuit board obtained through cutting, drilling, shading, copper plating and circuit manufacturing processes. The interior of the FPC board 10 may be a Pi (Polyimide) layer, and the first copper layer 11 is arranged on one side of the Pi layer.

[0045] In this embodiment, the FPC board 10 further has a second copper layer 12 opposite to the first copper layer 11 . The first copper layer 11 and the second copper layer 12 are respectively arranged on opposite sides of the Pi layer. A second pad PAD14 is provided on the second copper layer 12 .

[0046] S200 : attaching and pressing a first cover film 20 on the first copper layer 11 , wherein the first cover film 20 is provided with a first window hole 21 , and the first window hole 21 exposes the first pad PAD13 .

[0047] Specifically, the first covering film 20 can be drilled and opened in advance according to the design, and the corresponding hard board area and the first pad PAD13 area can be opened to obtain the first window hole 21. The first covering film 20 can protect and insulate the circuit layer on the first copper layer 11, and at the same time expose the first pad PAD13 that needs to be coated with solder mask ink. The first covering film 20 can be pressed and cured using conventional processes.

[0048] In this embodiment, a second cover film 50 is attached and pressed onto the second copper layer 12 . A second window hole 51 is provided on the second cover film 50 . The second window hole 51 exposes the second pad PAD14 .

[0049] Among them, the second covering film 50 can be drilled and opened in advance according to the design, and the corresponding hard board area and the second pad PAD14 area can be opened to obtain a second window hole 51. The second covering film 50 can protect the circuit layer on the insulating second copper layer 12, and at the same time expose the second pad PAD14 that needs to be coated with solder mask ink. The second covering film 50 can be pressed and cured using conventional processes.

[0050] S300 : Printing a first solder resist ink 30 on the first pad PAD13 .

[0051] Specifically, the first solder resist ink 30 may be directly printed on the side of the first cover film 20 facing away from the first copper layer 11 , and then exposed, developed and cured, that is, the first solder resist ink 30 is printed on the first pad PAD13 .

[0052] It can be understood that the main structure of the first cover film 20 is a PI (Polyimide) layer and an AD glue (Drylaminating adhesive AD) layer. The PI layer of the first cover film 20 contacts the first solder mask ink 30 and is relatively smooth.

[0053] In this embodiment, the second solder resist ink 60 is printed on the second pad PAD14. The second solder resist ink 60 can be directly printed on the side of the second cover film 50 facing away from the second copper layer 12, and then exposed, developed, and cured. In other words, the second solder resist ink 60 is printed on the second pad PAD14.

[0054] It can be understood that the main structure of the second cover film 50 is also a PI layer and an AD adhesive layer. The PI layer of the second cover film 50 is in contact with the second solder mask ink 60 and is relatively smooth.

[0055] Optionally, the first solder resist ink 30 can be printed on the side of the first cover film 20 away from the first copper layer 11 and pre-cured for about 5 minutes, and then the second solder resist ink 60 can be printed on the side of the second cover film 50 away from the second copper layer 12. After standing, it is pre-cured for 20-25 minutes, and then the first solder resist ink 30 and the second solder resist ink 60 are exposed by double-sided exposure. After development, the first solder resist ink 30 and the second solder resist ink 60 are cured.

[0056] S400 : Laminating the first PCB board 40 on the first copper layer 11 .

[0057] Specifically, the first PCB 40 may include an FR4 epoxy glass cloth laminate and two third copper layers 41 disposed on opposite sides of the FR4 epoxy glass cloth laminate. The first PCB 40 may be a circuit board obtained after cutting, exposing positioning holes, and laminating alignment holes. During lamination, a first prepreg 80 may be placed on the first copper layer 11. The first PCB 40 is then placed on the side of the first prepreg 80 facing away from the FPC 10. Rivets are then placed on the corresponding layers in the designed order to achieve precise alignment of the layers. Finally, vacuum pressure is applied to press the first PCB 40, the first prepreg 80, and the FPC 10 together.

[0058] In this embodiment, a second PCB 70 is laminated onto the second copper layer 12. The first PCB 40 may include an FR4 epoxy glass cloth laminate and two fourth copper layers 71 disposed on opposite sides of the FR4 epoxy glass cloth laminate. During the lamination process, a second prepreg 81 is first placed on the second copper layer 12. The second PCB 70 is then placed on the side of the second prepreg 81 facing away from the FPC board 10. Rivets are then placed on the corresponding layers in the designed sequence to ensure precise alignment of the layers. Finally, vacuum pressure is applied to laminate the second PCB 70, the second prepreg 81, and the FPC board 10 together.

[0059] It can be understood that the pressing of the first PCB board 40 and the second PCB board 70 on the first copper layer 11 can be performed simultaneously.

[0060] Optionally, before pressing the first PCB board 40, the second PCB board 70, the first prepreg 80, the second prepreg 81 and the FPC board 10 together, the first PCB board 40 and the second PCB board 70 are baked to remove moisture from their materials to prevent explosion of the boards due to pressure transfer during lamination.

[0061] Optionally, after laminating the first PCB 40 onto the first copper layer 11, the rigid-flex board can undergo processes such as outer layer drilling, plasma debonding, shadow copper plating, circuit fabrication, and ink printing of the outer rigid board area. The ink printing of the outer rigid board area involves printing a third solder mask ink 90 on the side of the first PCB 40 facing away from the FPC board 10, and printing a fourth solder mask ink 91 on the side of the second PCB 70 facing away from the FPC board 10.

[0062] S500 : removing a portion of the first PCB board 40 to expose the first solder resist ink 30 .

[0063] Specifically, the first PCB board 40 can be removed by laser peeling to expose the first solder mask ink 30 . In this embodiment, a portion of the second PCB board 70 is removed to expose the second solder mask ink 60 .

[0064] It can be understood that after removing a portion of the first PCB board 40 , a portion of the first copper layer 11 may be exposed, and after removing a portion of the second PCB board 70 , a portion of the second copper layer 12 may be exposed.

[0065] Optionally, after removing part of the first PCB board 40 and exposing the first solder mask ink 30 , the rigid-flex board may be further subjected to processes such as immersion gold deposition, character testing, functional testing, and appearance processing.

[0066] The method for manufacturing a flexible and rigid board provided in an embodiment of the present application first prints a first solder mask ink 30 on the first pad PAD13 of the first copper layer 11, then presses a first PCB board 40 on the first copper layer 11, and finally removes a portion of the first PCB board 40 to expose the first solder mask ink 30, thereby ensuring that the first solder mask ink 30 can better cover the first pad PAD13.

[0067] It can be understood that the method for manufacturing a flexible and rigid board provided in the embodiment of the present application first prints the second solder mask ink 60 on the second pad PAD14 of the second copper layer 12, then presses the second PCB board 70 on the second copper layer 12, and finally removes part of the second PCB board 70 and exposes the second solder mask ink 60, thereby ensuring that the second solder mask ink 60 can be well covered on the second pad PAD14.

[0068] Please refer to Figure 3 In some embodiments, before the first PCB board 40 is pressed onto the first copper layer 11, a first avoidance groove 42 is processed on the third copper layer 41; a first avoidance hole 801 is provided on the first prepreg 80, and the first avoidance hole 801 can be processed on the first prepreg 80 by laser cutting. When the first prepreg 80 is placed on the first copper layer 11, the first avoidance hole 801 exposes the first solder mask ink 30; when the first PCB board 40, the first prepreg 80 and the FPC board 10 are pressed together, the hole wall of the first avoidance hole 801, the first avoidance groove 42 and the first solder mask ink 30 are surrounded by a first cavity.

[0069] By adopting the above solution, when the first PCB board 40, the first prepreg 80 and the FPC board 10 are pressed together, the air remaining in the first cavity can be used to prevent the first PCB board 40 from squeezing the first solder mask ink 30, thereby preventing the second solder mask ink 60 from being damaged.

[0070] It is understandable that by adopting the above solution, the air remaining in the first cavity can also be used to prevent the high temperature and high pressure generated during pressing from squeezing the first solder mask ink 30 and causing damage to the second solder mask ink 60.

[0071] In this embodiment, before the second PCB board 70 is pressed onto the second copper layer 12, a second avoidance groove 72 is machined on the fourth copper layer 71; a second avoidance hole 811 is provided on the second prepreg 81, and the second avoidance hole 811 can be machined on the second prepreg 81 by laser cutting. When the second prepreg 81 is placed on the second copper layer 12, the second avoidance hole 811 exposes the second solder mask 60; when the second PCB board 70, the second prepreg 81, and the FPC board 10 are pressed together, the hole wall of the second avoidance hole 811, the second avoidance groove 72, and the second solder mask 60 are combined to form a second cavity. In this way, when the second PCB board 70, the second prepreg 81, and the FPC board 10 are pressed together, the air remaining in the second cavity can be used to prevent the second PCB board 70 and the high temperature and high pressure generated during the pressing from squeezing the second solder mask 60, resulting in damage to the second solder mask 60.

[0072] It can be understood that the first avoidance groove 42 may or may not pass through the first copper layer 11 , and the second avoidance groove 72 may or may not pass through the second copper layer 12 .

[0073] It can be understood that the portion of the first PCB board 40 located at the bottom of the first avoidance groove 42 can be removed by laser peeling to expose the first solder mask ink 30, and the portion of the second PCB board 70 located at the bottom of the second avoidance groove 72 can be removed by laser peeling to expose the second solder mask ink 60.

[0074] Optionally, the first avoidance groove 42 can be processed on the third copper layer 41 by exposure, development and etching, that is, according to the designed exposure film, the first PCB board 40 is exposed, developed and etched, the first copper layer 11 corresponding to the first avoidance groove 42 is etched away and other circuit production is completed.

[0075] It can be understood that the specific method of processing the second avoidance groove 72 on the fourth copper layer 71 can be similar to the specific method of processing the first avoidance groove 42 on the third copper layer 41 .

[0076] Please continue to refer to Figure 3 In some embodiments, the projection of the first avoidance hole 801 on the third copper layer 41 is located in the first avoidance groove 42, and the distance D between the projection of the first avoidance hole 801 on the third copper layer 41 and the side groove wall of the first avoidance groove 42 is 0.4mm-0.6mm, such as 0.4mm, 0.5mm or 0.6mm.

[0077] By adopting the above solution, the alignment deviation between the first avoidance hole 801 and the first avoidance groove 42 can be eliminated, ensuring that when the first PCB board 40, the first semi-cured sheet 80 and the FPC board 10 are pressed together, the third copper layer 41 on the first PCB board 40 will not damage the first solder mask ink 30.

[0078] Optionally, the projection of the first solder mask 30 on the third copper layer 41 is located inside the projection of the first avoidance hole 801 on the third copper layer 41. This further eliminates the misalignment between the first avoidance hole 801 and the first avoidance groove 42, ensuring that the third copper layer 41 on the first PCB 40 will not damage the first solder mask 30 when the first PCB 40, the first prepreg 80, and the FPC 10 are pressed together.

[0079] In this embodiment, D is 0.5 mm.

[0080] It can be understood that the specific structure and arrangement of the second avoidance hole 811 can be similar to the specific structure and arrangement of the first avoidance hole 801.

[0081] Please refer to Figure 3 In some embodiments, before printing the first solder resist ink 30 on the first pad PAD13 , the first copper layer 11 in the area where the first pad PAD13 is located is roughened.

[0082] By adopting the above solution, the bonding force between the first solder resist ink 30 and the first copper layer 11 can be improved, thereby preventing the first solder resist ink 30 from falling off the first copper layer 11 .

[0083] Among them, the first copper layer 11 in the area where the first pad PAD13 is located is roughened. The FPC board 10 to be processed can be first transferred to the horizontal browning line, and the first copper layer 11 in the area where the first pad PAD13 is located is roughened by micro-etching, alkali washing, pre-preg and browning processes. Then, the browned FPC board 10 is subjected to printing acid washing to wash away the browning film on its surface, so that the copper surface of the first copper layer 11 reaches a roughness of 1um to 3um, and then the first solder mask ink 30 can be printed on the first pad PAD13.

[0084] In this embodiment, before printing the second solder mask ink 60 on the second pad PAD 14, the second copper layer 12 in the area where the second pad PAD 14 is located is roughened. This improves the bonding strength between the second solder mask ink 60 and the second copper layer 12 and prevents the second solder mask ink 60 from falling off the second copper layer 12.

[0085] It can be understood that the specific process of roughening the second copper layer 12 in the area where the second pad PAD14 is located may be similar to the specific process of roughening the first copper layer 11 in the area where the first pad PAD13 is located.

[0086] Optionally, before printing the first solder mask ink 30 on the first pad PAD 13, the first cover film 20 forming the hole wall of the first window hole 21 is roughened. This can improve the bonding strength between the first solder mask ink 30 and the first cover film 20 and prevent the first solder mask ink 30 from falling off the first cover film 20.

[0087] It can be understood that when the roughening process is performed on the first covering film 20 constituting the hole wall of the first window hole 21 , only the PI layer on the first covering film 20 that contacts the first solder resist ink 30 may be roughened.

[0088] Among them, the first covering film 20 constituting the hole wall of the first window hole 21 is roughened by using a vertical plasma device, the first covering film 20 to be processed is placed in the device, and the first covering film 20 constituting the hole wall of the first window hole 21 is roughened by using a gas corresponding to the plasma roughening program, such as a comprehensive gas containing carbon tetrafluoride (CF4), oxygen (O2) and nitrogen (N2), and the processing conditions are: plasma power is 5kw, total processing time is 15min, CF4 flow rate is 0.18L, N2 flow rate is 0.36L, and O2 flow rate is 1.26L.

[0089] In this embodiment, before printing the second solder resist ink 60 on the second pad PAD 14, the second cover film 50 forming the hole wall of the second opening 51 is roughened. This improves the bonding strength between the second solder resist ink 60 and the second cover film 50, preventing the first solder resist ink 30 from falling off the second cover film 50.

[0090] It can be understood that when the second covering film 50 constituting the hole wall of the second window hole 51 is roughened, only the PI layer on the second covering film 50 that contacts the second solder mask ink 60 may be roughened.

[0091] It can be understood that the specific process of roughening the second covering film 50 constituting the hole wall of the second window hole 51 can be similar to the specific process of roughening the first covering film 20 constituting the hole wall of the first window hole 21 .

[0092] In a second aspect, an embodiment of the present application provides a rigid-flex board, which is manufactured by the rigid-flex board manufacturing method of the first aspect.

[0093] The rigid-flex board provided in the embodiment of the present application is manufactured by first printing the first solder mask ink 30 on the first pad PAD13 of the first copper layer 11, then pressing the first PCB board 40 on the first copper layer 11, and finally removing part of the first PCB board 40 to expose the first solder mask ink 30, thereby ensuring that the first solder mask ink 30 can better cover the first pad PAD13.

[0094] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for manufacturing a rigid-flex board, characterized in that: include: Providing an FPC board, the FPC board having a first copper layer, and a first pad PAD is provided on the first copper layer; Attaching and pressing a first cover film on the first copper layer, wherein the first cover film is provided with a first window hole, and the first window hole exposes the first pad PAD; Printing a first solder resist ink on the first pad PAD; Processing a first avoidance groove on the third copper layer of the first PCB board; placing a first prepreg on the first copper layer, wherein the first prepreg is provided with a first avoidance hole, and the first avoidance hole exposes the first solder mask ink; Placing the first PCB board on the side of the first prepreg facing away from the FPC board, and laminating the third copper layer to the first prepreg; Pressing the first PCB, the first prepreg, and the FPC together, so that the hole wall of the first avoidance hole, the first avoidance groove, and the first solder mask ink together form a first cavity, wherein the first cavity is used to accommodate air; A portion of the first PCB is removed to expose the first solder mask ink.

2. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The FPC board further comprises a second copper layer opposite to the first copper layer, and a second pad PAD is provided on the second copper layer. After providing an FPC board, the method for manufacturing a rigid-flex board further comprises: Attaching and pressing a second cover film on the second copper layer, wherein the second cover film is provided with a second window hole, and the second window hole exposes the second pad PAD; Printing a second solder resist ink on the second pad PAD; Laminating a second PCB board on the second copper layer; A portion of the second PCB is removed to expose the second solder mask ink.

3. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The projection of the first avoidance hole on the third copper layer is located in the first avoidance groove, and the distance between the projection of the first avoidance hole on the third copper layer and the side groove wall of the first avoidance groove is 0.4mm-0.6mm.

4. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: The first avoidance groove is processed on the third copper layer by exposure, development and etching.

5. The method for manufacturing a rigid-flex PCB according to claim 1, wherein: Removing a portion of the first PCB board and exposing the first solder mask ink includes: removing a portion of the first PCB board located at the bottom of the first avoidance groove by laser uncovering and exposing the first solder mask ink.

6. The method for manufacturing a rigid-flex PCB according to any one of claims 1 to 5, characterized in that: Before printing the first solder resist ink on the first pad PAD, the first copper layer in the area where the first pad PAD is located is roughened.

7. The method for manufacturing a rigid-flex PCB according to any one of claims 1 to 5, wherein: Before printing the first solder resist ink on the first pad PAD, the first covering film constituting the hole wall of the first window hole is roughened.

8. The method for manufacturing a rigid-flex PCB according to any one of claims 1 to 5, characterized in that: After the first PCB is laminated on the first copper layer, a third solder mask ink is printed on a side of the first PCB facing away from the FPC board, and then a portion of the first PCB is removed to expose the first solder mask ink.

9. A rigid-flex board, characterized in that: The rigid-flex board is manufactured by the rigid-flex board manufacturing method according to any one of claims 1 to 8.

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