Flexible circuit board and battery protection board

Abstract

The utility model discloses a flexible circuit board and a battery protection board, the flexible circuit board comprises at least one first metal layer, the flexible circuit board is provided with a first surface, and a part of the first metal layer close to the first surface is exposed out of the first surface; the flexible circuit board further comprises a shielding film, the shielding film covers the part, exposed out of the first surface, of the first metal layer, the shielding film comprises a second metal layer and insulating layers arranged on the two sides of the second metal layer, and the part, close to the second metal layer of the first surface, of the shielding film is exposed out of the insulating layers. The part of the first metal layer exposed out of the first surface is electrically connected with the part of the second metal layer exposed out of the insulating layer. Through electrical connection of the first metal layer and the second metal layer which are exposed out of the surface of the insulating layer, a better electromagnetic shielding effect is obtained, and the problem of short circuit caused by contact between the shielding film and other conductive circuits which do not need to be shielded on the flexible circuit board is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of flexible circuit boards and battery protection boards, in particular to a flexible circuit board and a battery protection board. Background Art

[0002] In integrated circuits, in order to ensure the normal operation of electronic components on circuit boards, it is generally necessary to perform electromagnetic shielding on the electronic components. First, it complies with the Electro Magnetic Compatibility (EMC) specification, and second, it prevents the electronic components from being interfered with by external electromagnetic waves (EMI) or from radiating electromagnetic waves generated by the electronic components. In recent years, the thickness of flexible circuit boards, which have been widely used in various fields, is relatively thin, and the anti-interference ability of electronic components on flexible circuit boards is relatively weak. The traditional anti-interference method for circuit boards is to install a metal shielding cover on the circuit board and connect it to the ground terminal to build a "Faraday cage" to achieve an effective electromagnetic shielding effect. However, due to the large size of the metal shielding cover, it is not suitable for thin and high-density flexible circuit boards.

[0003] Therefore, the prior art mostly uses surface mounted EMI shielding film to improve the anti-interference performance of flexible circuit boards. However, the prior art mostly performs overall mounting of EMI shielding film on flexible circuit boards, which has a high manufacturing cost. The overall mounted shielding film is also prone to contact with other conductive lines on the circuit board that do not require shielding, causing a short circuit, thereby affecting the electromagnetic shielding effect. Utility Model Content

[0004] The embodiments of the utility model provide a flexible circuit board and a battery protection board to solve the problem in the prior art that the integrally mounted shielding film easily causes a short circuit and has a poor electromagnetic shielding effect.

[0005] In order to solve the above technical problems, the embodiments of the present utility model disclose the following technical solutions:

[0006] According to a first aspect of the utility model, a circuit board is provided, wherein the flexible circuit board includes at least one first metal layer, the flexible circuit board has a first surface, and a portion of the first metal layer close to the first surface is exposed from the first surface; the flexible circuit board also includes a shielding film, the shielding film covers the portion of the first metal layer exposed from the first surface, wherein the shielding film includes a second metal layer and an insulating layer arranged on both sides of the second metal layer, and a portion of the second metal layer of the shielding film close to the first surface is exposed from the insulating layer; the portion of the first metal layer exposed from the first surface is electrically connected to the portion of the second metal layer exposed from the insulating layer.

[0007] Furthermore, the flexible circuit board includes a bending area and a non-bending area, and a portion of the first metal layer exposed from the first surface is arranged in the non-bending area.

[0008] Furthermore, a portion of the first metal layer that is exposed from the first surface is configured as a negative signal area.

[0009] Furthermore, a portion of the first metal layer that is not exposed from the first surface is configured as a positive signal area, and the positive signal area and the negative signal area are arranged at intervals.

[0010] Furthermore, the flexible circuit board also includes a wire, and the wire is arranged between the positive signal area and the negative signal area.

[0011] Furthermore, the flexible circuit board includes a first edge and a second edge that are relatively arranged, the first edge is close to the positive signal area, the second edge is close to the negative signal area, the distance between the edge of the shielding film and the first edge is 0, and the distance between the edge of the shielding film and the second edge is greater than or equal to a first preset threshold.

[0012] Furthermore, a distance between a portion of the first metal layer that is exposed from the first surface and an edge of the non-bending area is greater than or equal to a second preset threshold.

[0013] Furthermore, a distance between a portion of the second metal layer that is exposed from the insulating layer and an edge of the shielding film is greater than or equal to a third preset threshold.

[0014] Furthermore, a portion of the first metal layer exposed from the first surface is electrically connected to a portion of the second metal layer exposed from the insulating layer through a conductive adhesive.

[0015] According to a second aspect of the present invention, a battery protection board is provided, comprising a flexible circuit board as described in any one of the first aspects above.

[0016] One of the above technical solutions has the following advantages or beneficial effects:

[0017] In the embodiment of the utility model, by electrically connecting the metal layer in the flexible circuit board with the metal layer in the shielding film, a better electromagnetic shielding effect is obtained, the anti-interference performance of the flexible circuit board is improved, and at the same time, the problem of short circuit caused by contact between the shielding film and other conductive circuits that do not need to be shielded is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The technical solutions and other beneficial effects of the present invention will be made apparent by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0019] Figure 1 It is a plan view of a flexible circuit board provided according to an embodiment of the utility model;

[0020] Figure 2 is a cross-sectional schematic diagram of a flexible circuit board provided according to an embodiment of the utility model;

[0021] Figure 3 It is another plan view schematic diagram of a flexible circuit board provided according to an embodiment of the utility model;

[0022] The meanings of the figure marks are as follows: flexible circuit board-100; first surface-110; bending area-111; non-bending area 112; first edge-120; second edge-130; first metal layer-10; negative signal area-11; positive signal area-12; wire-13; shielding film-20; second metal layer-21; insulating layer-22; first insulating layer-30; second insulating layer-40; portion of the first metal layer exposed on the first surface-101; portion of the second metal layer exposed on the insulating layer-211. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and beneficial effects of the utility model clearer, the utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described in this specification are only for explaining the utility model, and are not intended to limit the utility model.

[0024] In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present utility model, the meaning of "multiple" refers to two or more, unless otherwise clearly and specifically defined.

[0025] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0026] In the present utility model, unless otherwise clearly stipulated and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0027] In view of the problems of high manufacturing cost and poor electromagnetic shielding effect caused by mounting shielding films on flexible circuit boards in the prior art, the utility model provides a flexible circuit board 100. Figure 1 Schematic diagram of a flexible circuit board 100 in an embodiment of the present invention. Figure 2 For along Figure 1 Schematic diagram of the cross section along the AA' direction.

[0028] like Figure 1 to Figure 2 As shown, the flexible circuit board 100 includes at least one first metal layer 10 . The flexible circuit board 100 has a first surface 110 . A portion 101 of the first metal layer 10 close to the first surface 110 is exposed from the first surface 110 .

[0029] In some embodiments, Figure 1 As shown, the flexible circuit board 100 includes a first insulating layer 30, a first metal layer 10 and a second insulating layer 40 which are stacked in sequence, wherein the materials of the first insulating layer 30 and the second insulating layer 40 may be polyimide (PI) or polyester (PET), and the first insulating layer 30 and the second insulating layer 40 are used to isolate the conductive layer to prevent short circuit and interference, wherein the second insulating layer 40 covers the first surface 110 of the flexible circuit board 100, provides electrical insulation performance on the surface of the flexible circuit board 100, and opens a window on the surface of the second insulating layer 40 to expose a portion of the first metal layer 10 close to the first surface 110. Figure 2As shown, on the first surface 110 of the flexible circuit board 100 , a plurality of portions 101 of the first metal layer 10 that are exposed from the first surface 110 may be arranged at intervals.

[0030] The flexible circuit board 100 further includes a shielding film 20, which covers a portion 101 of the first metal layer 10 that exposes the first surface 110, wherein the shielding film 20 includes a second metal layer 21 and an insulating layer 22 disposed on both sides of the second metal layer 21, and a portion 211 of the second metal layer 21 of the shielding film 20 that is close to the first surface 110 exposes the insulating layer 22. Figure 2 As shown, on one side of the shielding film 20 close to the first surface 110 , a plurality of portions 211 of the second metal layer 21 exposing the insulating layer 22 may be arranged at intervals.

[0031] The portion 101 of the first metal layer 10 exposed to the first surface 110 is electrically connected to the portion 211 of the second metal layer 21 exposed to the insulating layer 22. In some embodiments, in the thickness direction of the flexible circuit board 100, the projection of the portion 101 of the first metal layer 10 exposed to the first surface 110 and the projection of the portion 211 of the second metal layer 21 exposed to the insulating layer 22 at least partially overlap, and a conductive adhesive is applied at a position where the projection of the portion 101 of the first metal layer 10 exposed to the first surface 110 overlaps with the projection of the portion 211 of the second metal layer 21 exposed to the insulating layer 22, and the portion 101 of the first metal layer 10 exposed to the first surface 110 and the portion 211 of the second metal layer 21 exposed to the insulating layer 22 are electrically connected through the conductive adhesive.

[0032] A plurality of shielding films 20 may be provided on the flexible circuit board 100 and spaced apart from each other. Each shielding film 20 is electrically connected to the first metal layer 10 according to the above configuration.

[0033] In the embodiment of the utility model, in the area where the first metal layer 10 of the flexible circuit board 100 is exposed, the shielding film 20 covering it is electrically connected to the first metal layer 10 through the exposed second metal layer 21, thereby achieving a better shielding effect. In the area where the first metal layer 10 of the flexible circuit board 100 is not exposed, the shielding film 20 maintains electrical insulation with the first surface 110 of the flexible circuit board 100 covered thereunder, thereby preventing the shielding film 20 from contacting other conductive lines on the flexible circuit board 100 that do not need to be shielded and causing a short circuit.

[0034] In some embodiments, Figure 1 As shown, the portion of the first metal layer 10 that is exposed on the first surface 110 is configured as a negative signal region 11 . Specifically, the negative signal region 11 includes the portion 101 of the first metal layer 10 that is exposed on the first surface 110 and a portion that is electrically connected thereto.

[0035] In some embodiments, Figure 1As shown, a portion of the first metal layer 10 that is not exposed from the first surface 110 is configured as a positive signal area 12 , and the positive signal area 12 and the negative signal area 11 are arranged at intervals.

[0036] The negative pole portion of the flexible circuit board 100 needs to be connected to the shielding film 20 for electromagnetic shielding, while the positive pole portion of the flexible circuit board 100 needs to be electrically isolated from the shielding film 20. For the positive signal area 12 and the negative signal area 11 that are spaced apart, a portion of the first metal layer 10 of the negative signal area 11 is exposed to the first surface 110 and electrically connected to the second metal layer 21 of the shielding film 20, while the positive signal area 12 is not exposed to the first surface 110. There are two insulating layers between the positive signal area 12 and the shielding film 20 for protection, namely, a second insulating layer 40 covering the first surface 110 and an insulating layer 22 covering the surface of the shielding film 20, thereby ensuring the electrical isolation between the positive signal area 12 and the shielding film 20.

[0037] In some embodiments, Figure 2 As shown, the flexible circuit board 100 includes a first edge 120 and a second edge 130 that are arranged opposite to each other, the first edge 120 is close to the positive signal area 12, the second edge 130 is close to the negative signal area 11, the distance between the edge of the shielding film 20 and the first edge 120 is 0, and the distance between the edge of the shielding film 20 and the second edge 130 is greater than or equal to the first preset threshold value, and illustratively, the first preset threshold value is 0.5 mm. In other embodiments, the edge of the shielding film 20 on the side close to the first edge 120 may exceed the first edge 120, but the edge of the shielding film 20 on the side close to the second edge 130 may not exceed the second edge 130. For a single shielding film 20 cut out from a whole piece of material, its edge will expose the cross-section of the second metal layer 21 if it is not processed. If the distance between the edge of the shielding film 20 and the second edge 130 is 0 or the edge of the shielding film 20 exceeds the second edge 130, the exposed second metal layer 21 may contact the positive signal area 12, causing a short circuit.

[0038] In some embodiments, Figure 2 As shown, the flexible circuit board 100 includes a bending area 111 and a non-bending area 112, and the portion of the first metal layer 10 that exposes the first surface 110 is arranged in the non-bending area 112. In some embodiments, the bending area 111 and the non-bending area 112 are arranged in contact with each other, and the distance between the portion of the first metal layer 10 that exposes the first surface 110 and the edge of the non-bending area 112 is greater than or equal to a second preset threshold value. Exemplarily, the second preset threshold value can be 1mm. In the prior art, the shielding film integrally mounted on the surface of the flexible circuit board will affect the bending effect of the flexible circuit board because the shielding film itself is relatively thick. In the present application, the shielding film 20 is only arranged in the non-bending area 112 of the flexible circuit board 100, which avoids the problem of affecting the bending effect of the circuit board caused by the thick shielding film 20.

[0039] In some embodiments, Figure 2 As shown, the distance between the portion of the second metal layer 21 that exposes the insulating layer 22 and the edge of the shielding film 20 is greater than or equal to a third preset threshold value, and illustratively, the third preset threshold value is 0.5 mm. The portion of the second metal layer 21 that exposes the insulating layer 22 is formed by a window opening process, and illustratively, the window opening can be performed by a mechanical cutting process. The portion of the second metal layer 21 that exposes the insulating layer 22 maintains a distance greater than or equal to the third preset threshold value from the edge of the shielding film 20, which can avoid damage to the edge of the shielding film 20 due to limited precision during mechanical cutting, and is also beneficial to ensure the flatness of the insulating layer 22 adjacent to the window opening area.

[0040] In some embodiments, the distance between the edge of the portion 101 of the first metal layer 10 that exposes the first surface 110 and the edge of the flexible circuit board 100 is greater than or equal to a fourth preset threshold value, and illustratively, the fourth preset threshold value is 0.3 mm. The portion 101 of the first metal layer 10 that exposes the first surface 110 is formed by a window opening process, and illustratively, the window opening can be performed by a mechanical cutting process. The portion 101 of the first metal layer 10 that exposes the first surface 110 maintains a distance greater than or equal to the fourth preset threshold value from the edge of the flexible circuit board 100, which can avoid damage to the edge of the flexible circuit board 100 due to limited precision during mechanical cutting, and is also conducive to ensuring the flatness of the second insulating layer 40 adjacent to the window opening area.

[0041] In some embodiments, Figure 3 As shown, the flexible circuit board 100 further includes a wire 13, which is located in the first metal layer as a signal line and is used to connect to the connector ( Figure 3 The wire 13 is arranged between the positive signal area 12 and the negative signal area 11 at intervals, and has no electrical connection with the positive signal area 12 and the negative signal area 11. The distance between the edge of the portion 101 of the first metal layer 10 that exposes the first surface 110 and the wire 13 is greater than or equal to the fifth preset threshold value, which can prevent short circuits caused by short circuits between different networks. Exemplarily, the fifth preset threshold value is 0.3 mm.

[0042] In some embodiments, the portion 101 of the first metal layer 10 that exposes the first surface 110 is a rectangle, and the length or width of the rectangle is greater than or equal to the sixth preset threshold value, and illustratively, the sixth preset threshold value is 1 mm. The portion 101 of the first metal layer 10 that exposes the first surface 110 is formed by a window opening process, and illustratively, the window opening can be performed by a mechanical cutting process. The mechanical cutting process has certain precision limitations, and the minimum window opening size that can be produced is a square window opening with a side length of 1 mm.

[0043] The utility model also provides a battery protection board, including the above-mentioned flexible circuit board 100. The battery protection board is an integrated circuit board that protects rechargeable batteries, and can monitor the voltage of the battery cell and the current of the charging and discharging circuit, and instantly control the on and off of the current circuit. The battery protection board is usually composed of a circuit board and electronic components packaged on the circuit board. These electronic components include control ICs, MOS switches, precision resistors, and electricity meters. While being easily disturbed by the outside world, the magnetic field emitted by its own conductive circuit will also form electromagnetic interference to the outside world.

[0044] The flexible circuit board 100 with the shielding film as described above is used as a battery protection board, which can simultaneously meet the thinning requirements and electromagnetic shielding requirements of the battery protection board, reduce the occupied volume, and reduce the production cost.

[0045] The above embodiments are only used to help understand the structure and core concept of the utility model. For ordinary technicians in this technical field, the utility model can also be improved and modified without departing from the principle of the utility model, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

Claims

1. A flexible circuit board, characterized in that: The flexible circuit board includes at least one first metal layer, the flexible circuit board has a first surface, and a portion of the first metal layer close to the first surface is exposed from the first surface; The flexible circuit board further includes a shielding film, the shielding film covers a portion of the first metal layer that exposes the first surface, wherein the shielding film includes a second metal layer and an insulating layer disposed on both sides of the second metal layer, and a portion of the shielding film close to the second metal layer on the first surface exposes the insulating layer; A portion of the first metal layer exposed from the first surface is electrically connected to a portion of the second metal layer exposed from the insulating layer.

2. The flexible circuit board according to claim 1, characterized in that: The flexible circuit board includes a bending area and a non-bending area, and a portion of the first metal layer exposed from the first surface is disposed in the non-bending area.

3. The flexible circuit board as claimed in claim 2, characterized in that: The portion of the first metal layer exposed from the first surface is configured as a negative signal region.

4. The flexible circuit board as claimed in claim 3, characterized in that: A portion of the first metal layer that is not exposed from the first surface is configured as a positive signal area, and the positive signal area and the negative signal area are arranged at intervals.

5. The flexible circuit board as claimed in claim 4, characterized in that: The flexible circuit board also includes conductive lines located in the first metal layer, and the conductive lines are spaced apart and arranged between the positive signal area and the negative signal area.

6. The flexible circuit board as claimed in claim 4, characterized in that: The flexible circuit board includes a first edge and a second edge arranged opposite to each other, the first edge is close to the positive signal area, the second edge is close to the negative signal area, the distance between the edge of the shielding film and the first edge is 0, and the distance between the edge of the shielding film and the second edge is greater than or equal to a first preset threshold.

7. The flexible circuit board as claimed in claim 2, characterized in that: A distance between a portion of the first metal layer exposed from the first surface and an edge of the non-bending region is greater than or equal to a second preset threshold.

8. The flexible circuit board according to claim 1, characterized in that: A distance between a portion of the second metal layer exposed from the insulating layer and an edge of the shielding film is greater than or equal to a third preset threshold.

9. The flexible circuit board according to claim 1, characterized in that: A portion of the first metal layer exposed from the first surface is electrically connected to a portion of the second metal layer exposed from the insulating layer through a conductive adhesive.

10. A battery protection board, characterized in that: Comprising the flexible circuit board as claimed in any one of claims 1 to 9.

Images