Circuit board and electronic equipment

Abstract

A circuit board and electronic device, relating to but not limited to the field of circuit board technology, wherein the circuit board comprises a first circuit board, the first circuit board comprising a first substrate and a first circuit layer disposed on a first side of the first substrate, the first circuit layer comprising a first ground circuit; the circuit board further comprises a first protective layer and a first electromagnetic interference shielding layer stacked in sequence on a side of the first circuit layer away from the first substrate; the first protective layer is provided with a first opening, the first opening exposing at least a portion of the first ground circuit, the first opening being filled with a first conductive material, the height difference between the surface of the first conductive material and the surface of the first protective layer away from the first substrate being 0 to 2 microns, and the first conductive material connecting the first electromagnetic interference shielding layer and the first ground circuit. The circuit board of the disclosed embodiment can prevent the circuit board from partially warping or becoming uneven after a window is partially opened to expose the circuit layer.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to, but are not limited to, the technical field of circuit boards, and more particularly to a circuit board and an electronic device. Background Art

[0002] Electronic products are increasingly used in our lives, and circuit boards are a crucial component. To achieve grounding and electromagnetic shielding, some technologies require opening windows in the overlay covering the circuit layer to expose the grounding traces, allowing them to connect to the electromagnetic interference shielding film or conductive layer. However, this can cause localized warping and unevenness in the circuit board. Summary of the Invention

[0003] The embodiments of the present disclosure provide a circuit board and an electronic device, which can prevent the circuit board from being partially warped or uneven after a window is partially opened to expose a circuit layer.

[0004] An embodiment of the present disclosure provides a circuit board, comprising a first circuit board, wherein the first circuit board comprises a first substrate and a first circuit layer provided on a first side surface of the first substrate, wherein the first circuit layer comprises a first ground circuit; the circuit board further comprises a first protective layer and a first electromagnetic interference shielding layer stacked in sequence on a side of the first circuit layer away from the first substrate; the first protective layer is provided with a first opening, wherein the first opening exposes at least a portion of the first ground circuit, and the first opening is filled with a first conductive material, wherein the height difference between the surface of the first conductive material and the surface of the first protective layer away from the first substrate is 0 microns to 2 microns, and the first conductive material connects the first electromagnetic interference shielding layer and the first ground circuit.

[0005] Optionally, the first circuit board further includes a second circuit layer provided on the second side surface of the first substrate, and the second circuit layer includes a second ground circuit;

[0006] The circuit board further includes a first insulating layer, a second electromagnetic interference shielding layer, and a conductive layer stacked sequentially on a side of the second circuit layer away from the first substrate;

[0007] The first insulating layer and the second electromagnetic interference shielding layer are provided with a second opening, which exposes at least a portion of the second grounding line. The second opening is filled with a second conductive material. The height difference between the surface of the second conductive material and the surface of the second electromagnetic interference shielding layer away from the first substrate is 0 microns to 2 microns. The second conductive material connects the conductive layer and the second grounding line.

[0008] Optionally, the second conductive material is a metal material; or / and the material of the conductive layer is a conductive adhesive.

[0009] Optionally, the first conductive material is a metal material.

[0010] Optionally, the first protective layer includes a first covering layer and a first adhesive layer, and the first adhesive layer is located between the first covering layer and the first circuit layer.

[0011] Optionally, the circuit board includes a main body and a bendable portion located on a first side of the main body, the main body includes a plurality of stacked circuit boards, each of the circuit boards includes a substrate and at least one circuit layer provided on the substrate, the plurality of circuit boards includes the first circuit board, and the first circuit board extends to the bendable portion;

[0012] The first protective layer, the first electromagnetic interference shielding layer and the first opening are all located in the bendable portion.

[0013] Optionally, the main body and the bendable portion both include the first insulating layer, the second electromagnetic interference shielding layer and the conductive layer, and the second opening is located in the main body.

[0014] Optionally, the circuit board further comprises a binding portion located on a second side of the main body portion opposite to the first side;

[0015] The multiple circuit boards include a second circuit board, the second substrate and at least one circuit layer of the second circuit board extend to the binding part, and the circuit layer of the second circuit board extending to the binding part is provided with exposed binding pins, and the binding pins are configured to be bound and connected to an external circuit.

[0016] Optionally, the binding part includes a third circuit layer and a second protective layer stacked in sequence on the first side of the second substrate, the binding pin is provided at the end of the third circuit layer away from the main body, and the second protective layer exposes the binding pin; the binding part also includes a third protective layer provided on the second side of the second substrate.

[0017] Optionally, the second protective layer includes a second covering layer and a second adhesive layer, and the second adhesive layer is located between the second covering layer and the third circuit layer; or / and, the third protective layer includes a third covering layer and a third adhesive layer, and the third adhesive layer is located between the third covering layer and the second substrate.

[0018] Optionally, the multiple circuit boards also include a third circuit board, the first circuit board, the second circuit board and the third circuit board are stacked in sequence, two adjacent circuit boards are bonded together by an adhesive layer, and the first side of the first substrate is arranged toward the second circuit board.

[0019] Optionally, the second circuit board in the main body includes a third circuit layer and a fourth circuit layer respectively provided on two side surfaces of the second substrate, and the third circuit board includes a third substrate, and a fifth circuit layer and a sixth circuit layer respectively provided on two side surfaces of the third substrate;

[0020] The main body also includes a second insulating layer and a third electromagnetic interference shielding layer sequentially stacked on a side of the third circuit board away from the second circuit board, and the third electromagnetic interference shielding layer is integrally connected to the first electromagnetic interference shielding layer.

[0021] An embodiment of the present disclosure further provides an electronic device, comprising the circuit board described in any embodiment.

[0022] The circuit board of the embodiment of the present disclosure is filled with a first conductive material in the first opening of the first protective layer, and the height difference between the surface of the first conductive material and the surface of the first protective layer away from the first substrate is 0 microns to 2 microns. In this way, on the one hand, the first conductive material fills the step difference at the first opening of the first protective layer, ensuring that the surface of the first protective layer is flat without increasing the thickness of the circuit board. After the first electromagnetic interference shielding layer is attached to the first protective layer, the surface of the first electromagnetic interference shielding layer is also flat. In this way, when double-sided tape or other adhesive layers are attached to the first electromagnetic interference shielding layer, no bubbles or trapped air will be generated between the two, so that when the circuit board is attached to the back of the flexible OLED screen through double-sided tape or other adhesive layers, it will not cause poor film printing. On the other hand, the first conductive material fills the step difference at the first opening of the first protective layer. After the first electromagnetic interference shielding layer is attached to the first protective layer, the circuit board (for example, when the circuit board is a flexible circuit board) can achieve stress balance at the first opening to prevent the circuit board from warping. In addition, the first conductive material connects the first electromagnetic interference shielding layer and the first grounding line to achieve the shielding function of the first electromagnetic interference shielding layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0024] Figure 1a Schematic diagram of the cross-sectional structure of a circuit board of some technologies;

[0025] Figure 1b for Figure 1a Schematic diagram of the structure of the circuit board after being attached with double-sided tape;

[0026] Figure 2 is a schematic cross-sectional structural diagram of a circuit board according to some exemplary embodiments;

[0027] Figure 3 Schematic diagrams of planar structures of circuit boards according to other exemplary embodiments;

[0028] Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure at the AA position;

[0029] The accompanying drawings are:

[0030] 10. substrate, 11. circuit layer, 12. protective layer, 13. electromagnetic interference shielding layer;

[0031] 001, double-sided tape, 01, first double-sided tape, 02, second double-sided tape;

[0032] 21. Main body, 22. Bendable portion, 23. Binding portion, 211. Component area, 212. Connector, 221. Grounding area;

[0033] 31. First circuit board, 311. First substrate, 312. First circuit layer, 313. Second circuit layer,

[0034] 32. Second circuit board, 321. Second substrate, 322. Third circuit layer, 323. Fourth circuit layer,

[0035] 33. Third circuit board, 331. Third substrate, 332. Fifth circuit layer, 333. Sixth circuit layer,

[0036] 41. first adhesive layer, 42. second adhesive layer,

[0037] 51. First insulating layer, 52. Second insulating layer,

[0038] 61. First electromagnetic interference shielding layer, 62. Second electromagnetic interference shielding layer, 63. Third electromagnetic interference shielding layer,

[0039] 71. First protective layer, 711. First adhesive layer, 712. First covering layer,

[0040] 72. Second protective layer, 721. Second adhesive layer, 722. Second covering layer,

[0041] 73. Third protective layer, 731. Third adhesive layer, 732. Third covering layer,

[0042] 81. Conductive layer,

[0043] 91. A first conductive material, 92. A second conductive material. DETAILED DESCRIPTION

[0044] The technical solution of the present application will be further described below with reference to the accompanying drawings and through specific implementation methods. It should be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application.

[0045] Some technologies, such as Figure 1a As shown, Figure 1a This is a schematic diagram of the cross-sectional structure of some circuit boards. Because the circuit board needs to have higher electromagnetic shielding and signal anti-interference capabilities, an electromagnetic interference shielding film (referred to as EMI film) 13 is attached to its surface. By opening a window on the covering film (referred to as CVL) 12 of the circuit board, the EMI film 13 is connected to the ground line of the circuit layer (the circuit layer is provided on the substrate 10) 11, thereby realizing the electromagnetic shielding function of the EMI film 13. In this grounding method, at the grounding position of the EMI film 13, due to the window opening of the covering film 12, a local step difference (height difference) will be formed here. On the one hand, as Figure 1a As shown, since current consumer electronic products have higher requirements for circuit board shielding, the number of grounding points of the EMI film 13 on the circuit board is large and the area is small, resulting in an uneven surface of the circuit board and the step difference cannot be filled from the outer surface of the EMI film 13. In this case, Figure 1b As shown, Figure 1b for Figure 1a Schematic diagram of the structure of the circuit board after the double-sided tape is attached. When a thin double-sided tape 001 or other adhesive layer is attached to the surface of the circuit board (i.e., the outer surface of the EMI film 13), due to the uneven surface of the circuit board, bubbles and trapped air will form between the double-sided tape 001 and the EMI film 13 at the position M corresponding to the window of the covering film 12, resulting in when the circuit board is attached to the back of the flexible organic light-emitting diode (OLED) screen through the double-sided tape 001, the trapped air and bubbles will cause local material deformation, resulting in poor film printing; on the other hand, due to the step difference in the window area of ​​the covering film 12, after the EMI film 13 is attached, the circuit board in the window area (for example, when the circuit board is a flexible circuit board) will be warped due to stress pulling, affecting the assembly of the module.

[0046] An embodiment of the present disclosure provides a circuit board, comprising a first circuit board, wherein the first circuit board comprises a first substrate and a first circuit layer provided on a first side surface of the first substrate, wherein the first circuit layer comprises a first ground circuit; the circuit board further comprises a first protective layer and a first electromagnetic interference shielding layer stacked in sequence on a side of the first circuit layer away from the first substrate; the first protective layer is provided with a first opening, wherein the first opening exposes at least a portion of the first ground circuit, and the first opening is filled with a first conductive material, wherein the height difference between the surface of the first conductive material and the surface of the first protective layer away from the first substrate is 0 microns to 2 microns, and the first conductive material connects the first electromagnetic interference shielding layer and the first ground circuit.

[0047] The circuit board of the embodiment of the present disclosure is filled with a first conductive material in the first opening of the first protective layer, and the height difference between the surface of the first conductive material and the surface of the first protective layer away from the first substrate is 0 microns to 2 microns. In this way, on the one hand, the first conductive material fills the step difference at the first opening of the first protective layer, ensuring that the surface of the first protective layer is flat without increasing the thickness of the circuit board. After the first electromagnetic interference shielding layer is attached to the first protective layer, the surface of the first electromagnetic interference shielding layer is also flat. In this way, when double-sided tape or other adhesive layers are attached to the first electromagnetic interference shielding layer, no bubbles or trapped air will be generated between the two, so that when the circuit board is attached to the back of the flexible OLED screen through double-sided tape or other adhesive layers, it will not cause poor film printing. On the other hand, the first conductive material fills the step difference at the first opening of the first protective layer. After the first electromagnetic interference shielding layer is attached to the first protective layer, the circuit board (for example, when the circuit board is a flexible circuit board) can achieve stress balance at the first opening to prevent the circuit board from warping. In addition, the first conductive material connects the first electromagnetic interference shielding layer and the first grounding line to achieve the shielding function of the first electromagnetic interference shielding layer.

[0048] In the circuit board of the embodiment of the present disclosure, the height difference between the surface of the first conductive material and the surface of the first protective layer away from the first substrate is 0 microns to 2 microns, that is, the surface of the first conductive material and the surface of the first protective layer away from the first substrate can be flush, or the surface of the first conductive material is 0 microns to 2 microns higher or lower than the surface of the first protective layer away from the first substrate.

[0049] The circuit board of the embodiment of the present disclosure may be a flexible printed circuit board (FPC), a printed circuit board (PCB) or a rigid-flexible printed circuit board (RFPC). The embodiment of the present disclosure does not limit the type of the circuit board.

[0050] The circuit board of the embodiment of the present disclosure may be a single-sided circuit board, a double-sided circuit board or a multi-layer circuit board, and the number of circuit layers may be one or more layers, which is not limited in the embodiment of the present disclosure.

[0051] In some exemplary embodiments, Figure 2 As shown, Figure 2Schematic diagram of the cross-sectional structure of a circuit board of some exemplary embodiments. The circuit board includes a first circuit board 31, the first circuit board 31 includes a first substrate 311 and a first circuit layer 312 provided on a first side of the first substrate 311, the first circuit layer 312 including a first grounding circuit; the circuit board also includes a first protective layer 71 and a first electromagnetic interference shielding layer 61 stacked in sequence on a side of the first circuit layer 312 away from the first substrate 311; the first protective layer 71 has a first opening, the first opening exposes at least a portion of the first grounding circuit, the first opening is filled with a first conductive material 91, and the height difference between the surface of the first conductive material 91 and the surface of the first protective layer 71 away from the first substrate 311 is 0 microns to 2 microns ( Figure 2 In the example, the height difference is 0 micron, that is, the surface of the first conductive material 91 is flush with the surface of the first protective layer 71 away from the first substrate 311), and the first conductive material 91 connects the first electromagnetic interference shielding layer 61 and the first grounding line.

[0052] In this embodiment, the first circuit board 31 may further include a second circuit layer 313 provided on the second side surface of the first substrate 311, and the second circuit layer 313 includes a second grounding circuit; the circuit board may further include a second protective layer 72 and a second electromagnetic interference shielding layer 62 stacked in sequence on the side of the second circuit layer 313 away from the first substrate 311; the second protective layer 72 is provided with a second opening, and the second opening exposes at least a portion of the second grounding circuit, and the second opening is filled with a second conductive material 92, and the height difference between the surface of the second conductive material 92 and the surface of the second protective layer 72 away from the first substrate 311 is 0 microns to 2 microns, and the second conductive material 92 connects the second electromagnetic interference shielding layer 62 and the second grounding circuit.

[0053] In an example of this embodiment, Figure 2As shown, the first protective layer 71 may be provided with one or more first openings. The shape of the first openings may be rectangular, circular, polygonal, irregular, etc. The number and shape of the first openings are not limited in this embodiment. In one example of this embodiment, the material of the first substrate 311 may be polyimide (PI), polyetheretherketone (PEEK), or polyester. The material of the first circuit layer 312 and the second circuit layer 313 may be copper. In one example of this embodiment, the first conductive material 91 may be a metal material, such as any one or more of gold, silver, and copper. The first conductive material 91 may be filled into the first openings through an electroplating process or a coating process. For example, metallic copper may be filled into the first openings through an electroplating process, or silver paste may be applied to the first openings through a coating process and cured, ensuring that the height difference between the surface of the first conductive material 91 and the surface of the first protective layer 71 away from the first substrate 311 is 0 to 2 microns. The material and formation method of the second conductive material 92 may be the same as those of the first conductive material 91.

[0054] In one example of this embodiment, the first EMI shielding layer 61 may be a first EMI shielding film, which may include a protective film, a shielding functional layer sequentially stacked on one side of the protective film, and a conductive adhesive layer. The first EMI shielding film may be attached to the first protective layer 71 through a thermal compression process and contact the first conductive material 91. The shielding functional layer is connected to the first conductive material 91 via the conductive adhesive layer, thereby connecting the shielding functional layer to the first ground line.

[0055] In an example of this embodiment, Figure 2 As shown, the first protective layer 71 may include a first cover layer 712 and a first adhesive layer 711. The first adhesive layer 711 is located between the first cover layer 712 and the first circuit layer 312. The first cover layer 712 is bonded to the first circuit layer 312 via the first adhesive layer 711. In one example of this embodiment, the process of forming the first protective layer 71 may include: attaching a first cover film having the first opening to the surface of the first circuit layer 312. The first cover film includes the first cover layer 712 and the first adhesive layer 711 provided on one side of the first cover layer 712. The first cover film may be thermally pressed onto the first circuit layer 312 using a thermal pressing process (lamination process). During the thermal pressing process, the first adhesive layer 711 melts and bonds the first cover layer 712 to the first circuit layer 312. After forming the first protective layer 71, the first conductive material 91 is first filled inside the first opening to fill the step difference of the first protective layer 71 at the first opening, and then the first electromagnetic interference shielding layer (the first electromagnetic interference shielding layer can be an EMI film) 61 is attached to the first protective layer 71 and the first conductive material 91.

[0056] In one example of this embodiment, the second protective layer 72 may include a second cover layer 722 and a second adhesive layer 721, wherein the second adhesive layer 721 is located between the second cover layer 722 and the third circuit layer 322. The second protective layer 72 and the second electromagnetic interference shielding layer 62 may be arranged in the same manner as the first protective layer 71 and the first electromagnetic interference shielding layer 61.

[0057] The circuit board of the embodiment of the present disclosure is configured such that the first conductive material 91 is filled in the first opening of the first protective layer 71, and the height difference between the surface of the first conductive material 91 and the surface of the first protective layer 71 away from the first substrate 311 is 0 to 2 microns. In this way, the first conductive material 91 fills the step difference at the first opening of the first protective layer 71, thereby ensuring that the surface of the first protective layer 71 is flat without increasing the thickness of the circuit board. After the first electromagnetic interference shielding layer 61 is attached to the first protective layer 71, the surface of the first electromagnetic interference shielding layer 61 is also flat. Similarly, after the second electromagnetic interference shielding layer 62 is attached to the second protective layer 72, the surface of the second electromagnetic interference shielding layer 62 is also flat. In this way, after the first double-sided tape 01 is attached to the first electromagnetic interference shielding layer 61, and after the second double-sided tape 02 is attached to the second electromagnetic interference shielding layer 62, no bubbles or trapped air will be generated between the first double-sided tape 01 and the first electromagnetic interference shielding layer 61, and between the second double-sided tape 02 and the second electromagnetic interference shielding layer 62, so that when the circuit board is attached to the back of the flexible OLED screen through the double-sided tape or other adhesive layer, it will not cause poor film printing. In addition, the first conductive material 91 fills the step difference at the first opening of the first protective layer 71. Subsequently, after the first electromagnetic interference shielding layer 61 is attached to the first protective layer 71, the circuit board (for example, when the circuit board is a flexible circuit board) can achieve stress balance at the first opening to prevent the circuit board from warping at the first opening. Similarly, after the second electromagnetic interference shielding layer 62 is attached to the second protective layer 72, the circuit board (for example, when the circuit board is a flexible circuit board) can achieve stress balance at the second opening to prevent the circuit board from warping at the second opening.

[0058] In other exemplary embodiments, Figure 3 As shown, Figure 3Schematic diagrams of the planar structure of circuit boards according to other exemplary embodiments. The circuit board may be a rigid-flex board and may include a main body 21, a bendable portion 22 located on a first side of the main body 21, and a binding portion 23 located on a second side of the main body 21 opposite the first side. The main body 21 may include multiple circuit layers, and a component area 211 may be provided on one surface of the main body 21. Components such as chips, capacitors, and resistors may be placed in the component area 211. The main body 21 may be provided with a connector 212, which may be connected to an external circuit. The bendable portion 22 may be bendable and may be provided with a grounding area 221. At least a portion of the grounding circuit of the circuit board may be exposed by a film layer covering the grounding area 221. The exposed at least portion of the grounding circuit may be connected to the electromagnetic interference shielding layer of the circuit board to achieve the electromagnetic shielding function of the electromagnetic interference shielding layer. The binding portion 23 is used to achieve a binding connection between the circuit board and the external circuit. In some examples, when the circuit board is used in a display device, the circuit board can be bound to the display panel via the binding portion 23, and the circuit board can be connected to the mainboard of the display device via the connector 212. One or more openings can also be provided on the circuit board to avoid certain components or structures of the display device.

[0059] In some exemplary embodiments, Figure 4 As shown, Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure at position AA in the figure. The circuit board of this embodiment includes a first circuit board 31, the first circuit board 31 includes a first substrate 311 and a first circuit layer 312 provided on a first side surface of the first substrate 311, the first circuit layer 312 including a first grounding circuit; the circuit board also includes a first protective layer 71 and a first electromagnetic interference shielding layer 61 sequentially stacked on a side of the first circuit layer 312 away from the first substrate 311; the first protective layer 71 is provided with a first opening, the first opening exposes at least a portion of the first grounding circuit, the first opening is filled with a first conductive material 91, and the height difference between the surface of the first conductive material 91 and the surface of the first protective layer 71 away from the first substrate 311 is 0 microns to 2 microns ( Figure 4 In the example, the height difference is 0 micron, that is, the surface of the first conductive material 91 is flush with the surface of the first protective layer 71 away from the first substrate 311), and the first conductive material 91 connects the first electromagnetic interference shielding layer 61 and the first grounding line.

[0060] In the circuit board of this embodiment, a first conductive material 91 is filled within the first opening of the first protective layer 71. The height difference between the surface of the first conductive material 91 and the surface of the first protective layer 71 away from the first substrate 311 is 0 to 2 microns. Thus, the first conductive material 91 fills the step difference at the first opening of the first protective layer 71, ensuring a smooth surface of the first protective layer 71 without increasing the thickness of the circuit board. This ensures that the surface of the first electromagnetic interference shielding layer 61 is also smooth after the first electromagnetic interference shielding layer 61 is attached to the first protective layer 71. Furthermore, the first conductive material 91 fills the step difference at the first opening of the first protective layer 71. Subsequently, after the first electromagnetic interference shielding layer (which may be an EMI film in some examples) 61 is attached to the first protective layer 71, stress balance can be achieved at the first opening of the circuit board (for example, when the circuit board at the first opening is a flexible circuit board), preventing the circuit board from warping at the first opening.

[0061] In one example of this embodiment, the first conductive material 91 can be a metal material, such as any one or more of gold, silver, and copper. The first conductive material 91 can be filled in the first opening by an electroplating process or a coating process. For example, metal copper can be filled in the first opening by an electroplating process, or silver paste can be dotted in the first opening and solidified by a coating process. The first conductive material 91 is formed in the first opening by an electroplating process or a coating process, which can meet the different step filling requirements of different circuit boards. Under different step filling requirements, the height difference between the surface of the first conductive material 91 and the surface of the first protective layer 71 away from the first substrate 311 can be ensured to be 0 microns to 2 microns, which can ensure that the first electromagnetic interference shielding layer 61 and the first grounding line are reliably connected.

[0062] In one example of this embodiment, the first protective layer 71 may be provided with one or more first openings. The shape of the first openings may be rectangular, circular, polygonal, irregular, etc. This embodiment does not limit the number and shape of the first openings. In some examples, the area where the first openings are located is Figure 3 The landing area in 221.

[0063] In one example of this embodiment, the first EMI shielding layer 61 may be a first EMI shielding film, which may include a protective film, a shielding functional layer sequentially stacked on one side of the protective film, and a conductive adhesive layer. The first EMI shielding film may be attached to the first protective layer 71 through a thermal compression process and contact the first conductive material 91. The shielding functional layer is connected to the first conductive material 91 via the conductive adhesive layer, thereby connecting the shielding functional layer to the first ground line.

[0064] In one example of this embodiment, the first protective layer 71 may include a first cover layer 712 and a first adhesive layer 711. The first adhesive layer 711 is located between the first cover layer 712 and the first circuit layer 312, and the first cover layer 712 is bonded to the first circuit layer 312 via the first adhesive layer 711. The first cover layer 712 may be made of polyimide, and the first adhesive layer 711 may be made of epoxy resin or acrylic. Exemplarily, the process of forming the first protective layer 71 may include: attaching a first cover film having a first opening to the surface of the first circuit layer 312, the first cover film including the first cover layer 712 and the first adhesive layer 711 disposed on one side of the first cover layer 712. The first cover film may be thermally laminated to the first circuit layer 312 using a thermal lamination process. During the thermal lamination process, the first adhesive layer 711 melts and bonds the first cover layer 712 to the first circuit layer 312. After forming the first protection layer 71 , the first opening is filled with a first conductive material 91 to fill the step of the first protection layer 71 at the first opening. Then, the first EMI shielding layer 61 is attached to the first protection layer 71 and the first conductive material 91 .

[0065] In an example of this embodiment, the thickness of the first substrate 311 can be 10 microns to 15 microns, for example, 12.5 microns; the thickness of the first circuit layer 312 can be 10 microns to 15 microns, for example, 12 microns; the first protective layer 71 includes a first covering layer 712 and a first adhesive layer 711, and the thickness of the first protective layer 71 can be 25 microns to 35 microns, for example, the thickness of the first covering layer 712 is 12.5 microns, and the thickness of the first adhesive layer 711 is 20 microns, that is, the thickness of the first protective layer 71 is 32.5 microns, then the thickness of the first conductive material 91 is 30.5 microns to 34.5 microns, for example, 32.5 microns; the thickness of the first electromagnetic interference shielding layer 61 can be 10 microns to 20 microns, for example, 16 microns.

[0066] In some exemplary embodiments, Figure 4As shown, the first circuit board 31 may further include a second circuit layer 313 provided on the second side surface of the first substrate 311, and the second circuit layer 313 includes a second grounding circuit; the circuit board further includes a first insulating layer 51, a second electromagnetic interference shielding layer 62, and a conductive layer 81 stacked sequentially on the side of the second circuit layer 313 away from the first substrate 311; the first insulating layer 51 and the second electromagnetic interference shielding layer 62 are provided with a second opening (the second opening penetrates the first insulating layer 51 and the second electromagnetic interference shielding layer 62), the second opening exposes at least a portion of the second grounding circuit, and the second opening is filled with a second conductive material 92, and the height difference between the surface of the second conductive material 92 and the surface of the second electromagnetic interference shielding layer 62 away from the first substrate 311 is 0 microns to 2 microns ( Figure 4 In the example, the height difference is 0 micron, that is, the surface of the second conductive material 92 is flush with the surface of the second electromagnetic interference shielding layer 62 away from the first substrate 311), and the second conductive material 92 connects the conductive layer 81 and the second ground line.

[0067] In one example of this embodiment, the second conductive material 92 can be a metal material, such as any one or more of gold, silver, and copper. The second conductive material 92 can be filled into the second opening by an electroplating process or a coating process. For example, metallic copper can be filled into the second opening by an electroplating process, or silver paste can be dotted into the second opening by a coating process and then solidified. The use of an electroplating process or a coating process to form the second conductive material 92 in the second opening can meet the different step-filling requirements of different circuit boards. Under different step-filling requirements, the height difference between the surface of the second conductive material 92 and the surface of the second electromagnetic interference shielding layer 62 away from the first substrate 311 can be ensured to be 0 microns to 2 microns, thereby ensuring that the conductive layer 81 and the second grounding line are reliably connected, thereby achieving grounding of the conductive layer 81.

[0068] In one example of this embodiment, the material of the first insulating layer 51 can be insulating ink, such as PSR ink. The material of the second EMI shielding layer 62 can be a metal material, such as silver, and can be formed by an electroplating process. The material of the conductive layer 81 can be conductive adhesive. In other examples, the first insulating layer 51 can be a cover film having the second opening, the cover film including an insulating film and an adhesive layer provided on one side of the insulating film, the cover film being laminated to the second circuit layer 313 via the adhesive layer.

[0069] In some exemplary embodiments, Figure 3 、 Figure 4As shown, the circuit board may include a main body 21 and a bendable portion 22 located on a first side of the main body 21, the main body 21 may include a plurality of stacked circuit boards, each of the circuit boards including a substrate and at least one circuit layer provided on the substrate, the plurality of circuit boards including the first circuit board 31, the first circuit board 31 extending to the bendable portion 22; the first protective layer 71, the first electromagnetic interference shielding layer 61 and the first opening are all located in the bendable portion 22.

[0070] In one example of this embodiment, the first substrate 311, first circuit layer 312, and second circuit layer 313 of the first circuit board 31 may all extend to the bendable portion 22, that is, both the main portion 21 and the bendable portion 22 include the first circuit board 31. In one example of this embodiment, both the main portion 21 and the bendable portion 22 may include the first insulating layer 51, the second electromagnetic interference shielding layer 62, and the conductive layer 81. The second opening may be located in either the main portion 21 or the bendable portion 22. The number of circuit layers in the bendable portion 22 is less than that in the main portion 21, and the fewer circuit layers in the bendable portion 22 facilitates bending.

[0071] In an example of this embodiment, the thickness of the second circuit layer 313 can be 15 microns to 25 microns, for example, 21 microns; the thickness of the first insulating layer 51 can be 20 microns to 30 microns, for example, 25 microns; the thickness of the second electromagnetic interference shielding layer 62 can be 10 microns to 20 microns, for example, 16 microns; the total thickness of the first insulating layer 51 and the second electromagnetic interference shielding layer 62 is, for example, 41 microns, then the thickness of the second conductive material 92 is 39 microns to 43 microns, for example, 41 microns; the thickness of the conductive layer 81 can be different in the main body 21 and the bendable part 22, for example, the thickness of the conductive layer 81 of the main body 21 can be 100 microns to 200 microns, for example, 150 microns, and the thickness of the conductive layer 81 of the bendable part 22 can be 20 microns to 40 microns, for example, 30 microns.

[0072] In some exemplary embodiments, Figure 4 As shown, the circuit board may further include a binding portion 23 located on a second side of the main body 21 opposite to the first side; the plurality of circuit boards include a second circuit board 32, a second substrate 321 and at least one circuit layer of the second circuit board 32 extending to the binding portion 23, and the circuit layer of the second circuit board 32 extending to the binding portion 23 is provided with exposed binding pins ( Figure 4 The binding pin is configured to be bound and connected to an external circuit.

[0073] In an example of this embodiment, the binding portion 23 may include a third circuit layer 322 (the third circuit layer 322 is a circuit layer of the second circuit board 32) and a second protective layer 72 stacked in sequence on the first side surface of the second substrate 321, and the binding pin is provided at the end of the third circuit layer 322 away from the main body 21, and the second protective layer 72 exposes the binding pin; the binding portion 23 may also include a third protective layer 73 provided on the second side surface of the second substrate 321.

[0074] In one example of this embodiment, the second protective layer 72 may include a second cover layer 722 and a second adhesive layer 721. The second adhesive layer 721 is located between the second cover layer 722 and the third circuit layer 322. The third protective layer 73 may include a third cover layer 732 and a third adhesive layer 731. The third adhesive layer 731 is located between the third cover layer 732 and the second substrate 321. The second cover layer 722 and the third cover layer 732 may both be made of polyimide. The second adhesive layer 721 and the third adhesive layer 731 may be made of epoxy resin or acrylic. Exemplarily, the formation process of the second protective layer 72 and the third protective layer 73 can be the same. Taking the formation process of the second protective layer 72 as an example, a second covering film with a third opening is affixed to the surface of the third circuit layer 322. The second covering film includes a second covering layer 722 and a second adhesive layer 721 provided on one side of the second covering layer 722. The second covering film can be hot-pressed on the third circuit layer 322 by a hot pressing process. During the hot pressing process, the second adhesive layer 721 melts and adheres the second covering layer 722 to the third circuit layer 322, and the third opening exposes the binding pins of the third circuit layer 322.

[0075] In an example of this embodiment, the thickness of the second substrate 321 can be 10 microns to 30 microns, for example, 20 microns; the thickness of the third circuit layer 322 can be 10 microns to 20 microns, for example, 16 microns; the second protective layer 72 includes a second covering layer 722 and a second adhesive layer 721, and the thickness of the second protective layer 72 can be 25 microns to 35 microns, for example, the thickness of the second covering layer 722 is 12.5 microns, and the thickness of the second adhesive layer 721 is 20 microns; the third protective layer 73 includes a third covering layer 732 and a third adhesive layer 731, and the thickness of the third protective layer 73 can be 25 microns to 35 microns, for example, the thickness of the third covering layer 732 is 12.5 microns, and the thickness of the third adhesive layer 731 is 20 microns.

[0076] In some exemplary embodiments, Figure 4As shown, the multiple circuit boards may further include a third circuit board 33. The first circuit board 31, the second circuit board 32, and the third circuit board 33 may be stacked sequentially, with adjacent circuit boards bonded together by an adhesive layer. The first side of the first substrate 311, on which the first circuit layer 312 is provided, may be disposed toward the second circuit board 32. The side of the second substrate 321, on which the third circuit layer 322 is provided, may be disposed toward the first circuit board 31. Within the main body 21, the first circuit board 31 and the second circuit board 32 may be bonded together by a first adhesive layer 41, and the third circuit board 33 and the second circuit board 32 may be bonded together by a second adhesive layer 42.

[0077] In one example of this embodiment, the second circuit board 32 within the main body 21 may include a third circuit layer 322 and a fourth circuit layer 323, respectively disposed on two side surfaces of the second substrate 321. The third circuit layer 322 may be located on a first side surface of the second substrate 321 facing the first circuit board 31, and the fourth circuit layer 323 may be located on a second side surface of the second substrate 321 facing the third circuit board 33. The first circuit layer 312 of the first circuit board 31 is located on the first side surface of the first substrate 311 facing the second circuit board 32, and the second circuit layer 313 of the first circuit board 31 is located on the second side surface of the first substrate 311 facing away from the second circuit board 32. The third circuit board 33 includes a third substrate 331, and a fifth circuit layer 332 and a sixth circuit layer 333, respectively disposed on two side surfaces of the third substrate 331. The fifth circuit layer 332 may be located on the first side surface of the third substrate 331 facing the second circuit board 32, and the sixth circuit layer 333 may be located on the second side surface of the third substrate 331 facing away from the second circuit board 32. In this example, the first adhesive layer 41 can be bonded between the first circuit layer 312 of the first circuit board 31 and the third circuit layer 322 of the second circuit board 32, and the second adhesive layer 42 can be bonded between the fourth circuit layer 323 of the second circuit board 32 and the fifth circuit layer 332 of the third circuit board 33. The main body 21 of the circuit board in this example has six circuit layers, and each of the three circuit boards includes a substrate and two circuit layers respectively provided on two side surfaces of the substrate. In other examples, the number of circuit layers of the main body 21 can be designed as needed, for example, it can be three or four layers. The material of the substrate of each of the three circuit boards can be polyimide, polyetheretherketone or polyester, and the material of each circuit layer can be copper. In some examples, the formation process of each circuit board may include: providing a substrate, the substrate including an insulating substrate and a copper layer covering both surfaces of the insulating substrate (there may or may not be an adhesive layer between the insulating substrate and the copper layer); if the thickness of the copper layer of the substrate cannot reach the required circuit layer thickness, a copper layer of a certain thickness may be electroplated on the copper layer of the substrate; and forming the required circuit layer on the copper layers on both surfaces through processes such as exposure, development, and etching.

[0078] In one example of this embodiment, the main body 21 may further include a second insulating layer 52 and a third electromagnetic interference shielding layer 63 stacked in sequence on the side of the third circuit board 33 away from the second circuit board 32. The second insulating layer 52 may be provided on the sixth circuit layer 333 of the third circuit board 33, and the material of the second insulating layer 52 may be insulating ink, such as PSR ink. In other examples, the second insulating layer 52 may be a covering film, the covering film including an insulating film and an adhesive layer provided on one side of the insulating film, and the covering film is pressed onto the sixth circuit layer 333 through the adhesive layer. The third electromagnetic interference shielding layer 63 and the first electromagnetic interference shielding layer 61 may be connected as one piece, for example, the third electromagnetic interference shielding layer 63 and the first electromagnetic interference shielding layer 61 are the same electromagnetic interference shielding film, which is attached to the main body 21 and the bendable portion 22, or the third electromagnetic interference shielding layer 63 and the first electromagnetic interference shielding layer 61 are both made of the same metal material and can be formed simultaneously on the main body 21 and the bendable portion 22 through the same electroplating process. Figure 4 As shown, the surface of the circuit board near the third circuit board 33 has a certain height difference between the main body 21 and the bendable portion 22. The portion of the main body 21 protruding from the bendable portion 22 includes multiple circuit layers of the second circuit board 32 and the third circuit board 33. The end surfaces of these multiple circuit layers near the bendable portion 22 are Figure 4 It appears to be exposed in the figure, but in the actual circuit board manufacturing process, in the process of forming the insulating layer on the surface of the circuit layer, and in the process of bonding adjacent circuit boards with an adhesive layer, the materials forming the insulating layer and the adhesive layer will partially overflow the edge of the circuit board, thereby covering the end faces of the multiple circuit layers close to the bendable portion 22. In this way, the subsequently formed third electromagnetic interference shielding layer 63 and the first electromagnetic interference shielding layer 61 will not contact the end faces of the multiple circuit layers close to the bendable portion 22.

[0079] In an example of this embodiment, the thickness of the fourth circuit layer 323 can be 10 microns to 20 microns, for example, 16 microns; the thickness of the third substrate 331 can be 10 microns to 15 microns, for example, 12.5 microns; the thickness of the fifth circuit layer 332 can be 10 microns to 20 microns, for example, 12 microns; the thickness of the sixth circuit layer 333 can be 15 microns to 25 microns, for example, 21 microns; the thickness of the second insulating layer 52 can be 20 microns to 30 microns, for example, 25 microns; the thickness of the third electromagnetic interference shielding layer 63 can be 10 microns to 20 microns, for example, 16 microns; the thickness of the first adhesive layer 41 can be 30 microns to 50 microns, for example, 40 microns; the thickness of the second adhesive layer 42 can be 30 microns to 50 microns, for example, 40 microns.

[0080] The circuit board of the disclosed embodiment can be applied to a variety of display modules (such as OLED display modules, LCD display modules, etc.). The circuit board can include a display circuit and a touch circuit. The display circuit and the touch circuit can be arranged on different circuit layers. The circuit board is bound and connected to the display panel of the display module via a binding portion 23. The bendable portion 22 of the circuit board can be bent to the back of the display panel and fixed to the back of the display panel.

[0081] The present disclosure also provides an electronic device comprising the circuit board described in any of the embodiments. The electronic device may be a display device, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, navigation system, or other product or component with a display function. In some examples, the electronic device may be a touch display device.

[0082] In the description of the embodiments of the present application, it should be noted that the terms "upper", "lower", "left", "right", "top", "inside", "outside", "axial", "four corners", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only simplified descriptions for the convenience of describing the embodiments of the present application, and do not indicate or imply that the structure referred to has a specific orientation, is constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present application.

[0083] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, the terms "connect," "fixed connection," "installation," and "assembly" should be understood in a broad sense. For example, they may refer to a fixed connection, a detachable connection, or an integral connection. The terms "installation," "connection," and "fixed connection" may refer to a direct connection, an indirect connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present application based on the specific circumstances.

Claims

1. A circuit board, characterized in that: The first circuit board includes a first substrate and a first circuit layer provided on a first side surface of the first substrate, wherein the first circuit layer includes a first ground circuit; The circuit board further includes a first protection layer and a first electromagnetic interference shielding layer stacked in sequence on a side of the first circuit layer away from the first substrate; The first protective layer is provided with a first opening, the first opening exposing at least a portion of the first grounding line, the first opening being filled with a first conductive material, the height difference between a surface of the first conductive material and a surface of the first protective layer away from the first substrate being 0 micrometers to 2 micrometers, and the first conductive material connecting the first electromagnetic interference shielding layer and the first grounding line; The circuit board includes a main body and a bendable portion located on a first side of the main body. The main body includes a plurality of circuit boards stacked in sequence, each of the circuit boards including a substrate and at least one circuit layer provided on the substrate. The plurality of circuit boards include a first circuit board, a second circuit board, and a third circuit board. The first circuit board extends to the bendable portion, and the first protective layer, the first electromagnetic interference shielding layer, and the first opening are all located in the bendable portion. The second circuit board and the third circuit board do not extend to the bendable portion. The main body further includes a third electromagnetic interference shielding layer stacked on a side of the third circuit board away from the second circuit board, and the third electromagnetic interference shielding layer is integrally connected to the first electromagnetic interference shielding layer.

2. The circuit board according to claim 1, wherein: The first circuit board further includes a second circuit layer provided on the second side surface of the first substrate, and the second circuit layer includes a second ground circuit; The circuit board further includes a first insulating layer, a second electromagnetic interference shielding layer, and a conductive layer stacked sequentially on a side of the second circuit layer away from the first substrate; The first insulating layer and the second electromagnetic interference shielding layer are provided with a second opening, which exposes at least a portion of the second grounding line. The second opening is filled with a second conductive material. The height difference between the surface of the second conductive material and the surface of the second electromagnetic interference shielding layer away from the first substrate is 0 microns to 2 microns. The second conductive material connects the conductive layer and the second grounding line.

3. The circuit board according to claim 2, wherein: The second conductive material is a metal material; or / and the material of the conductive layer is a conductive adhesive.

4. The circuit board according to claim 1, wherein: The first conductive material is a metal material.

5. The circuit board according to claim 1, wherein: The first protective layer includes a first covering layer and a first adhesive layer, and the first adhesive layer is located between the first covering layer and the first circuit layer.

6. The circuit board according to claim 2, wherein: The main body and the bendable portion both include the first insulating layer, the second electromagnetic interference shielding layer, and the conductive layer, and the second opening is located in the main body.

7. The circuit board according to claim 2, wherein: The circuit board further includes a binding portion located on a second side of the main body portion opposite to the first side; The second substrate and at least one circuit layer of the second circuit board extend to the binding portion, and the circuit layer of the second circuit board extending to the binding portion is provided with exposed binding pins, and the binding pins are configured to be bound and connected to an external circuit.

8. The circuit board according to claim 7, wherein: The binding part includes a third circuit layer and a second protective layer stacked in sequence on the first side of the second substrate, the binding pin is provided at the end of the third circuit layer away from the main body, and the second protective layer exposes the binding pin; the binding part also includes a third protective layer provided on the second side of the second substrate.

9. The circuit board according to claim 8, wherein: The second protective layer includes a second covering layer and a second adhesive layer, and the second adhesive layer is located between the second covering layer and the third circuit layer; or / and, the third protective layer includes a third covering layer and a third adhesive layer, and the third adhesive layer is located between the third covering layer and the second substrate.

10. The circuit board according to claim 7, wherein: Two adjacent circuit boards are bonded together by an adhesive layer, and the first side surface of the first substrate is arranged toward the second circuit board.

11. The circuit board according to claim 10, wherein: The second circuit board in the main body includes a third circuit layer and a fourth circuit layer respectively provided on two side surfaces of the second substrate; the third circuit board includes a third substrate, and a fifth circuit layer and a sixth circuit layer respectively provided on two side surfaces of the third substrate; The main body further includes a second insulating layer stacked on a side of the third circuit board away from the second circuit board, and the second insulating layer is closer to the third circuit board than the third electromagnetic interference shielding layer.

12. An electronic device, characterized in that: A circuit board comprising the circuit board according to any one of claims 1 to 11.

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