Packaging adhesive film and flexible circuit board

Abstract

In order to overcome the problem that an existing flexible circuit board has electromagnetic interference, the utility model provides a packaging adhesive film which comprises a first adhesive film layer, a first binder layer, a signal shielding layer, a second adhesive film layer and a second binder layer, the first binder layer is clamped between the first adhesive film layer and the second adhesive film layer, and the signal shielding layer is clamped between the first adhesive film layer and the second adhesive film layer. The signal shielding layer is located between the first adhesive layer and the second adhesive film layer, the second adhesive layer is located on the surface of the side, away from the signal shielding layer, of the second adhesive film layer, and the signal shielding layer comprises a conductive shielding pattern, a conductive outgoing line and a grounding terminal. The conductive shielding pattern comprises a plurality of first conductive wires and a plurality of second conductive wires, the first conductive wires and the second conductive wires are vertically crossed to form a net-shaped pattern, one end of the conductive lead-out wire is electrically connected with the conductive shielding pattern, and the other end of the conductive lead-out wire is electrically connected with the grounding terminal.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of flexible circuit board, concretely relates to a kind of encapsulation adhesive film and flexible circuit board. BACKGROUND

[0002] With the continuous development of electronic products, the demand for lightweight, miniaturization and multi-functional flexible circuit board (FPC board) is increasing. However, in the process of high-frequency signal transmission, electromagnetic interference (EMI) problem becomes particularly prominent, which has a negative impact on signal integrity and circuit performance. Traditional flexible circuit board has deficiencies in electromagnetic compatibility (EMC), and it is difficult to meet the requirements of modern electronic products for high efficiency and stability. Although the material of the encapsulation adhesive film has been improved in the prior art, for example, a certain conductive filler is added to the adhesive film, but the encapsulation adhesive film itself requires a high dielectric constant, which contradicts the demand for reducing electromagnetic interference. The addition of conductive filler will inevitably lead to a decrease in dielectric constant, therefore, simply improving the material of the adhesive film cannot solve the problem of electromagnetic interference in the process of high-frequency signal transmission of the flexible circuit board. SUMMARY

[0003] In view of the problem of electromagnetic interference existing in the existing flexible circuit board, the utility model provides an encapsulation adhesive film and a flexible circuit board.

[0004] The utility model solves the above-mentioned technical problems by adopting the following technical solutions:

[0005] On the one hand, the utility model provides an encapsulation adhesive film, which comprises a first adhesive film layer, a first adhesive layer, a signal shielding layer, a second adhesive film layer and a second adhesive layer. The first adhesive layer is clamped between the first adhesive film layer and the second adhesive film layer. The signal shielding layer is located between the first adhesive layer and the second adhesive film layer. The second adhesive layer is located on the side surface of the second adhesive film layer away from the signal shielding layer. The signal shielding layer comprises a conductive shielding pattern, a conductive lead-out wire and a ground terminal. The conductive shielding pattern comprises a plurality of first conductive wires and a plurality of second conductive wires. The plurality of first conductive wires are parallel to each other. The plurality of second conductive wires are parallel to each other. The first conductive wires and the second conductive wires are perpendicular to each other to form a mesh pattern. One end of the conductive lead-out wire is electrically connected to the conductive shielding pattern. The other end of the conductive lead-out wire is electrically connected to the ground terminal. The first adhesive film layer is provided with a first through hole corresponding to the position of the ground terminal. The second adhesive film layer is provided with a second through hole corresponding to the position of the ground terminal. The first adhesive layer is provided with a third through hole corresponding to the position of the ground terminal. The second adhesive layer is provided with a fourth through hole corresponding to the position of the ground terminal.

[0006] Optionally, the conductive shielding pattern is located within a projection range of the first adhesive film layer on the second adhesive film layer, and the grounding terminal is located at a position close to an end of the first adhesive film layer.

[0007] Optionally, the first conductive line and the second conductive line are conductive silver paste coatings.

[0008] Optionally, the first adhesive film layer and the second adhesive film layer are polyimide layers.

[0009] Optionally, the packaging adhesive film further comprises a third adhesive layer, the third adhesive layer is located on a surface of the first adhesive film layer away from the first adhesive layer, and the third adhesive layer is provided with a fifth through hole corresponding to a position of the grounding terminal.

[0010] Optionally, the first adhesive layer, the second adhesive layer and the third adhesive layer are selected from epoxy adhesive layers.

[0011] Optionally, the thickness of the first adhesive layer is 20-60 μm, the thickness of the second adhesive layer is 10-40 μm, the thickness of the third adhesive layer is 20-60 μm, the thickness of the first adhesive film layer is 30-100 μm, and the thickness of the second adhesive film layer is 30-100 μm.

[0012] Optionally, the packaging adhesive film further comprises a first release layer and a second release layer, the first release layer is located on a surface of the third adhesive layer away from the first adhesive film layer, and the second release layer is located on a surface of the second adhesive layer away from the second adhesive film layer.

[0013] Optionally, the first release layer and the second release layer are polyethylene terephthalate layers.

[0014] In still another aspect, the present application provides a flexible circuit board, comprising at least one flexible circuit layer, the flexible circuit layer comprises a conductive circuit and a packaging adhesive film as described above which are stacked with each other, the conductive circuit layer is located within a projection of the conductive shielding pattern, and the conductive circuit layer and the grounding terminal are misaligned with each other.

[0015] According to the packaging adhesive film, the signal shielding layer is arranged between the first adhesive film layer and the second adhesive film layer to shield electromagnetic interference between conductive circuits on the flexible circuit board, and application of the flexible circuit board in the high-frequency signal transmission field is met, and meanwhile, in order to ensure that the signal shielding layer does not break when the flexible circuit board is bent, the signal shielding layer is arranged as a mesh structure formed by interweaving a plurality of first conductive lines and a plurality of second conductive lines, the mesh structure can adaptively deform along with bending of the flexible circuit board, so that the signal shielding layer breaking and being unable to be grounded is avoided, and even if individual points break, the overall performance is not affected; on the other hand, in order to ensure that the signal shielding layer functions, the conductive lead-out wire is connected to the grounding terminal, and corresponding through holes are arranged in the first adhesive film layer, the first adhesive layer, the second adhesive film layer and the second adhesive layer to expose the grounding terminal, when the multilayer flexible circuit layer is laminated, the mutual electrical connection of the grounding terminals can be ensured, and meanwhile, the mutual connection of the flexible circuit board and the external grounding wire during installation is facilitated, and installation difficulty is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic view of the packaging adhesive film provided by an embodiment of the present application;

[0017] Reference signs in the drawings of the specification are as follows:

[0018] 1, first adhesive film layer; 11, first through hole; 2, second adhesive film layer; 21, second through hole; 3, first adhesive layer; 31, third through hole; 4, second adhesive layer; 41, fourth through hole; 5, third adhesive layer; 51, fifth through hole; 6, signal shielding layer; 61, conductive shielding pattern; 611, first conductive line; 612, second conductive line; 62, conductive lead-out wire; 63, grounding terminal; 7, first release layer; 8, second release layer. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0020] In the description of the present application, it should be understood that the terms "thickness", "upper", "lower" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0021] Referring to Figure 1The utility model discloses an embodiment provides a kind of encapsulation adhesive film, including first adhesive film layer 1, first adhesive layer 3, signal shielding layer 6, second adhesive film layer 2 and second adhesive layer 4, the first adhesive layer 3 is clamped between the first adhesive film layer 1 and the second adhesive film layer 2, the signal shielding layer 6 is located between the first adhesive layer 3 and the second adhesive film layer 2, the second adhesive layer 4 is located the second adhesive film layer 2 side surface away from the signal shielding layer 6, the signal shielding layer 6 includes conductive shielding pattern 61, conductive lead-out wire 62 and ground terminal 63, the conductive shielding pattern 61 includes multiple first conductive line 611 and multiple second conductive line 612, multiple the first conductive line 611 is parallel, multiple the second conductive line 612 is parallel, and the first conductive line 611 and the second conductive line 612 are perpendicular to cross to form mesh pattern, one end of the conductive lead-out wire 62 is electrically connected the conductive shielding pattern 61, another end of the conductive lead-out wire 62 is electrically connected the ground terminal 63, the first adhesive film layer 1 is equipped with first through-hole 11 corresponding the position of ground terminal 63, the second adhesive film layer 2 is equipped with second through-hole 21 corresponding the position of ground terminal 63, the first adhesive layer 3 is equipped with third through-hole 31 corresponding the position of ground terminal 63, the second adhesive layer 4 is equipped with fourth through-hole 41 corresponding the position of ground terminal 63.

[0022] Signal shielding layer 6 is arranged between the first adhesive film layer 1 and the second adhesive film layer 2 to shield electromagnetic interference between conductive lines on the flexible circuit board, meeting the application of the flexible circuit board in the high-frequency signal transmission field, and to prevent the signal shielding layer 6 from breaking when the flexible circuit board is bent, the signal shielding layer 6 is arranged in a mesh structure formed by interlacing multiple first conductive lines 611 and multiple second conductive lines 612, which can adaptively deform with the bending of the flexible circuit board, thereby avoiding the situation that the signal shielding layer 6 breaks and cannot be grounded, and even if individual points break, the overall performance is not affected; on the other hand, to ensure the function of the signal shielding layer 6, the conductive lead-out wire 62 is connected to the ground terminal 63, and corresponding through holes are provided in the first adhesive film layer 1, the first adhesive layer 3, the second adhesive film layer 2 and the second adhesive layer 4 to expose the ground terminal 63, which can ensure the mutual electrical connection of the ground terminals 63 when the multi-layer flexible circuit is stacked, and also facilitates the mutual connection of the flexible circuit board and the external ground wire during installation, reducing the installation difficulty.

[0023] In an embodiment, the conductive shielding pattern 61 is located within the projection range of the first adhesive film layer 1 on the second adhesive film layer 2, and the ground terminal 63 is located at a position close to the end of the first adhesive film layer 1.

[0024] The conductive shielding pattern 61 is located in the projection range of the first adhesive film layer 1 on the second adhesive film layer 2, which can ensure the comprehensive coverage of the conductive shielding pattern 61 by the first adhesive film layer 1 and the second adhesive film layer 2, avoid the exposure of the conductive shielding pattern 61 or the electrical interference with the conductive circuit of the flexible circuit board or the external electrical connection structure, and ensure the shielding effect and stability of the conductive shielding pattern 61.

[0025] The ground terminal 63 is arranged at the position close to the end of the first adhesive film layer 1, which can avoid the influence on the main structure of the flexible circuit board and facilitate the subsequent electrical connection installation.

[0026] In an embodiment, the first conductive line 611 and the second conductive line 612 are conductive silver paste coatings.

[0027] The conductive silver paste coating has the characteristics of high electrical conductivity, convenient processing, and low thickness. The higher electrical conductivity has better electromagnetic shielding effect. Moreover, the conductive silver paste coating can be formed on the surface of the second adhesive film layer 2 by coating and curing, and has high adhesion without the need for additional adhesives. In addition, the thickness of the conductive silver paste coating is relatively low, only 1-5 μm, which has little effect on the overall thickness of the packaging adhesive film.

[0028] In other embodiments, the first conductive line 611 and the second conductive line 612 can also be selected from other types of conductive coatings. Specifically, in some fields with high requirements for the transparency of the flexible circuit board, the first conductive line 611 and the second conductive line 612 can use indium tin oxide coating. Compared with the conductive silver paste coating, the electrical conductivity of the indium tin oxide coating is lower and the electromagnetic shielding effect is slightly worse, but it has a higher light transmittance, which can meet the requirements of some transparent flexible circuit boards.

[0029] In an embodiment, the first adhesive film layer 1 and the second adhesive film layer 2 are polyimide layers.

[0030] Polyimide has extremely high heat resistance and can maintain its mechanical and electrical properties in high temperature environments. This characteristic makes it very suitable for use in flexible circuit boards that need to withstand soldering temperatures or work in high temperature environments. At the same time, it can provide good flexibility while maintaining high strength, which allows the flexible circuit board to be bent, folded, or even rolled without damage, suitable for complex shape designs and applications. Polyimide has excellent electrical insulation properties, which can effectively isolate the circuit to prevent short circuits and other electrical faults, improving the reliability of the product.

[0031] In an embodiment, the encapsulation adhesive film further comprises a third adhesive layer 5, which is located on the surface of the first adhesive layer 3 away from the first adhesive layer 1, and the third adhesive layer 5 is provided with a fifth through hole 51 corresponding to the position of the ground terminal 63.

[0032] When multiple flexible circuit layers need to be stacked, the third adhesive layer 5 can be used for mutual adhesion, and when the encapsulation adhesive film is used as a bottom layer and a top layer, the third adhesive layer 5 can also be omitted.

[0033] In an embodiment, the first adhesive layer 3, the second adhesive layer 4 and the third adhesive layer 5 are selected from an epoxy adhesive layer.

[0034] The epoxy adhesive has the effect of resisting high temperature and can maintain good adhesion effect under high temperature conditions. In some application scenarios with relatively low requirements for temperature resistance, the first adhesive layer, the second adhesive layer 4 and the third adhesive layer 5 can also be selected from an acrylic adhesive.

[0035] In an embodiment, the thickness of the first adhesive layer 3 is 20-60 μm, the thickness of the second adhesive layer 4 is 10-40 μm, the thickness of the third adhesive layer 5 is 20-60 μm, the thickness of the first adhesive layer 1 is 30-100 μm, and the thickness of the second adhesive layer 2 is 30-100 μm.

[0036] In an embodiment, the encapsulation adhesive film further comprises a first release layer 7 and a second release layer 8, the first release layer 7 is located on the surface of the third adhesive layer 5 away from the first adhesive layer 1, and the second release layer 8 is located on the surface of the second adhesive layer 4 away from the second adhesive layer 2.

[0037] The first release layer 7 and the second release layer 8 are used to temporarily protect the encapsulation adhesive film, so as to facilitate the storage and transfer of the encapsulation adhesive film, and avoid the third adhesive layer 5 and the second adhesive layer 4 from adhering to external dust or other impurities. When multiple flexible circuit layers are stacked, the first release layer 7 and the second release layer 8 should be exposed according to the need to expose the third adhesive layer 5 and the second adhesive layer 4, so as to facilitate the adhesion with other flexible circuit layers.

[0038] In an embodiment, the first release layer 7 and the second release layer 8 are polyethylene terephthalate layers.

[0039] In one embodiment, the present application provides a flexible circuit board, comprising at least one flexible circuit layer, the flexible circuit layer comprises mutually laminated conductive circuit and encapsulation adhesive film as described above, the conductive circuit layer is located within the projection of the conductive shielding pattern 61, and the conductive circuit layer is mutually staggered with the ground terminal 63.

[0040] By setting the conductive circuit layer and the ground terminal 63 mutually staggered, the influence of the ground terminal 63 on the conductive circuit layer is avoided, and meanwhile the exposure of the ground terminal 63 in each flexible circuit layer is ensured, so that the ground terminals 63 in each flexible circuit layer are electrically connected with each other, in some embodiments, the plurality of ground terminals 63 can be integrated by ultrasonic welding, and the welded ground terminal 63 is further welded with an external ground wire.

[0041] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An encapsulating film, characterized in that, The device comprises a first adhesive film layer, a first adhesive layer, a signal shielding layer, a second adhesive film layer, and a second adhesive layer. The first adhesive layer is sandwiched between the first adhesive film layer and the second adhesive film layer. The signal shielding layer is located between the first adhesive layer and the second adhesive film layer. The second adhesive layer is located on the side of the second adhesive film layer facing away from the signal shielding layer. The signal shielding layer includes a conductive shielding pattern, conductive leads, and a grounding terminal. The conductive shielding pattern includes multiple first conductive lines and multiple second conductive lines. The multiple first conductive lines are parallel to each other, and the multiple second conductive lines are parallel to each other. The first conductive lines and the second conductive lines intersect perpendicularly to form a mesh pattern. One end of the conductive lead is electrically connected to the conductive shielding pattern, and the other end of the conductive lead is electrically connected to the grounding terminal. The first adhesive film layer has a first through hole corresponding to the position of the grounding terminal, the second adhesive film layer has a second through hole corresponding to the position of the grounding terminal, the first adhesive layer has a third through hole corresponding to the position of the grounding terminal, and the second adhesive layer has a fourth through hole corresponding to the position of the grounding terminal.

2. The encapsulating film according to claim 1, characterized in that, The conductive shielding pattern is located within the projection range of the first adhesive layer onto the second adhesive layer, and the grounding terminal is located near the end of the first adhesive layer.

3. The encapsulating film according to claim 1, characterized in that, The first conductive line and the second conductive line are coated with conductive silver paste.

4. The encapsulating film according to claim 1, characterized in that, The first adhesive film layer and the second adhesive film layer are polyimide layers.

5. The encapsulating film according to claim 1, characterized in that, The encapsulating film further includes a third adhesive layer, which is located on the surface of the first film layer away from the first adhesive layer, and the third adhesive layer has a fifth through hole corresponding to the position of the grounding terminal.

6. The encapsulating film according to claim 5, characterized in that, The first adhesive layer, the second adhesive layer, and the third adhesive layer are selected from epoxy adhesive layers.

7. The encapsulating film according to claim 5, characterized in that, The thickness of the first adhesive layer is 20~60μm, the thickness of the second adhesive layer is 10~40μm, the thickness of the third adhesive layer is 20~60μm, the thickness of the first adhesive film layer is 30~100μm, and the thickness of the second adhesive film layer is 30~100μm.

8. The encapsulating film according to claim 5, characterized in that, The encapsulating film further includes a first release layer and a second release layer, wherein the first release layer is located on the surface of the third adhesive layer opposite to the first film layer, and the second release layer is located on the surface of the second adhesive layer opposite to the second film layer.

9. The encapsulating film according to claim 8, characterized in that, The first release layer and the second release layer are polyethylene terephthalate layers.

10. A flexible circuit board, characterized in that, It includes at least one flexible circuit layer, the flexible circuit layer comprising superimposed conductive lines and an encapsulating film as described in any one of claims 1 to 7, the conductive circuit layer being located within the projection of the conductive shielding pattern, and the conductive circuit layer being offset from the grounding terminal.

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