Flexible circuit boards and display modules

Abstract

The present invention relates to a flexible circuit board for connecting a display panel. The flexible circuit board comprises a substrate, including: a main body region; a first binding region provided at one end of the main body region, the first binding region being provided with a solder pad; a transition region between the first binding region and the main body region, the transition region being provided with a transition structure, wherein both the solder pad and the transition structure are located on a first surface of the substrate, and the thickness of the transition structure in a direction perpendicular to the substrate is less than the thickness of the solder pad in the direction perpendicular to the substrate. The present invention also relates to a display module.

Description

Technical Field

[0001] The present invention relates to the technical field of display product manufacturing, and in particular to a flexible circuit board and a display module. Background Art

[0002] With the continued development of AMOLED (Active Matrix / Organic Light Emitting Diode), flexible and full-screen displays will undoubtedly be a trend in the coming years. However, the development of new technologies inevitably brings new technical challenges. As foldable phones and laptops become larger and larger, they are facing unprecedented challenges. As the size of foldable products increases, the resolution will also increase. The bonding of multiple FPCs or COFs (chip-on-film) is inevitable. However, as the bonding area increases, the risk of short circuits in the bonding area also increases exponentially. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a flexible circuit board and a display module to solve the problem that short circuits are prone to occur in the binding connection of the flexible circuit board.

[0004] In order to achieve the above-mentioned object, the technical solution adopted in the embodiment of the present invention is: a flexible circuit board for connecting a display panel, wherein the flexible circuit board includes a substrate, including:

[0005] Main area;

[0006] A first binding area is provided at one end of the main body area, and a pad is provided in the first binding area;

[0007] There is a transition area between the first binding area and the main body area, and the transition area is provided with a transition structure, wherein,

[0008] The pad and the transition structure are both located on the first surface of the substrate, and the thickness of the transition structure in a direction perpendicular to the substrate is smaller than the thickness of the pad in the direction perpendicular to the substrate.

[0009] Optionally, along a direction away from the first surface of the substrate, the main area is sequentially provided with a first conductive layer and a first covering layer, the pad includes a second conductive layer and a third conductive layer sequentially provided, and the transition structure includes a transition film layer provided on the substrate;

[0010] The thickness of the second conductive layer in a direction perpendicular to the substrate is the same as the thickness of the transition film layer in a direction perpendicular to the substrate.

[0011] Optionally, the substrate has a second surface arranged opposite to the first surface, a sixth conductive layer is arranged on the second surface, the pad is connected to the sixth conductive layer through a via arranged on the substrate, and the sixth conductive layer is connected to the first conductive layer through a via arranged on the substrate.

[0012] Optionally, along a direction away from the first surface of the substrate, the main region is sequentially provided with a first conductive layer and a first covering layer, the pad includes a second conductive layer and a third conductive layer sequentially provided, and the transition structure includes a fourth conductive layer and a transition film layer;

[0013] The first conductive layer, the second conductive layer and the fourth conductive layer are arranged on the same layer.

[0014] Optionally, the material of the fourth conductive layer includes copper.

[0015] Optionally, along a direction away from the first surface of the substrate, the main region is sequentially provided with a first conductive layer and a first covering layer, the pad includes a second conductive layer, a fifth conductive layer, and a third conductive layer that are sequentially provided, and the transition structure includes a fourth conductive layer and a transition film layer;

[0016] The first conductive layer, the second conductive layer and the fourth conductive layer are arranged on the same layer.

[0017] Optionally, materials of the fourth conductive layer and the fifth conductive layer both include copper.

[0018] Optionally, the materials of the first conductive layer and the second conductive layer both include copper, and the material of the third conductive layer includes at least one of gold, nickel, and a gold-nickel alloy.

[0019] Optionally, the thickness of the transition structure is 10-12 um, and the difference between the thickness of the pad and the thickness of the transition structure is 8-10 um.

[0020] Optionally, a sixth conductive layer is provided on a second surface of the substrate opposite to the first surface, the sixth conductive layer is located on the main region, and a second covering layer is provided on a side of the sixth conductive layer away from the substrate.

[0021] Optionally, in the first binding area, a reinforcement layer is provided on the second surface of the substrate.

[0022] An embodiment of the present invention further provides a display module, comprising a display panel and the above-mentioned flexible circuit board, wherein the display panel comprises a display area, a second binding area, and an edge area that are adjacently arranged;

[0023] The second binding area is provided with a pad that is bound and connected to the pad of the flexible circuit board, and at least a portion of the orthographic projection of the transition structure on the display panel is located on the edge area.

[0024] The beneficial effects of the present invention are as follows: the thickness of the transition structure in the direction perpendicular to the substrate is less than the thickness of the pad in the direction perpendicular to the substrate. When the flexible circuit board is bound to the display panel, the transition structure enters the edge area of the display panel, avoiding exposure of the pad and not affecting the binding connection between the flexible circuit board and the display panel, thereby solving the problem of easy short circuit between the flexible circuit board and the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram showing the state before the flexible circuit board and the display panel are bound and connected in the related art;

[0026] Figure 2 Schematic diagram showing the state before the flexible circuit board and the display panel are connected together in accordance with the present invention Figure 1 ;

[0027] Figure 3 Schematic diagram of the laminated structure of the flexible circuit board in the embodiment of the present invention Figure 1 ;

[0028] Figure 4 Schematic diagram of the laminated structure of the flexible circuit board in the embodiment of the present invention Figure 2 ;

[0029] Figure 5 Schematic diagram of the laminated structure of the flexible circuit board in the embodiment of the present invention Figure 3 ;

[0030] Figure 6 A schematic diagram showing the structure of a display module according to an embodiment of the present invention;

[0031] Figure 7 Schematic diagram showing the state before the flexible circuit board and the display panel are connected together in accordance with the present invention Figure 2 . DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] refer to Figure 1 The flexible circuit board includes a main body area, a first binding area is provided at one end of the main body area, a transition area is provided between the first binding area and the main body area, the first binding area is provided with a first pad 10, and the transition area is provided with a transition structure 20. In order to prevent the first pad 10 from breaking when bending, the transition structure covers part of the first pad 10, and the end of the junction of the transition structure 20 and the first pad 10 is arranged in a wavy shape. In order to ensure the flatness of the first pad 10, the transition structure 20 is located outside the display panel. Therefore, a part of the pad 10 must be exposed relative to the display panel. Figure 1 The distance b between the end of the transition structure 20 close to the first pad 10 and the edge of the display panel is approximately 0.1 mm, and the distance a between the edge of the display panel and the second pad 20 is approximately 0.2 mm. These dimensions are the key dimensions that lead to defects. After analysis, it was confirmed that carbon residue was left on the edge of the display panel when it was cut, forming a carbonized area (the carbonized area is located in the edge area with a width a in the first direction). The carbonized area contains carbide (carbide is a short name, and the carbide contains display panel debris, and the display panel debris contains ITO debris). During the binding connection, the carbide is pressed between the first pad 10 of the flexible circuit board and the second pad 30 of the display panel. The presence of carbide causes a short circuit between the two signal lines, and the short-circuited signal lines are random, resulting in random dark lines or non-lighting defects in the binding area.

[0035] refer to Figure 2-Figure 5 In order to solve the above technical problems, this embodiment provides a flexible circuit board for connecting a display panel. The flexible circuit board includes a substrate, including:

[0036] Main area 101;

[0037] A first binding area 103 is provided at one end of the main body area 101 , and a pad 10 is provided in the first binding area 103 ;

[0038] There is a transition area 102 between the first binding area 103 and the main body area 101, and the transition area 102 is provided with a transition structure, wherein:

[0039] The pad 10 and the transition structure are both located on the first surface 106 of the substrate 100;

[0040] Furthermore, the thickness of the transition structure in the direction perpendicular to the substrate 100 is smaller than the thickness of the pad 10 in the direction perpendicular to the substrate 100 .

[0041] With the above technical solution, since the thickness of the transition structure in the direction perpendicular to the substrate 100 is less than the thickness of the pad 10 in the direction perpendicular to the substrate 100, when the flexible circuit board is bound to the display panel, the transition structure enters the edge area of the display panel, that is, at least part of the orthographic projection of the transition structure on the display panel is located in the edge area of the display panel. Figure 2 This prevents the pad 10 from being exposed, protects the pad 10, and prevents the exposed pad 10 from contacting the carbonized area of the display panel (the carbonized area is located in the edge area), thereby solving the problem of easy short circuit between the flexible circuit board and the display panel. Moreover, since the thickness of the transition structure in the direction perpendicular to the substrate 100 is less than the thickness of the pad 10 in the direction perpendicular to the substrate 100, even if the transition structure extends between the display panel and the flexible circuit board, it will not affect the flatness of the binding area, and will not affect the binding connection between the flexible circuit board and the display panel.

[0042] In this embodiment, the end portion where the transition structure meets the pad 10 is wavy, which improves the bending resistance of the pad 10, thereby avoiding breakage of the copper wire due to bending of the pad 10 and affecting the normal use of the product.

[0043] The specific structural forms of the transition structure and the pad 10 can be various, as long as the thickness of the transition structure in the direction perpendicular to the substrate 100 is less than the thickness of the pad 10 in the direction perpendicular to the substrate 100, and when the display panel is bound and connected, at least part of the orthographic projection of the transition structure on the display panel is located in the edge area of the display panel (at least part of which overlaps with the carbonized area). The following specifically introduces several specific structural forms of the flexible circuit board in this embodiment.

[0044] refer to Figure 3In some implementations of this embodiment, along a direction away from the first surface 106 of the substrate 100, the main region 101 is sequentially provided with a first conductive layer 31 and a first cover layer 40, the pad 10 includes a second conductive layer 11 and a third conductive layer 13 sequentially provided, and the transition structure includes a transition film layer 21 provided on the substrate 100;

[0045] The thickness of the second conductive layer 11 in a direction perpendicular to the substrate 100 is the same as the thickness of the transition film layer 21 in a direction perpendicular to the substrate 100;

[0046] The substrate 100 has a second surface 107 opposite to the first surface 106. A sixth conductive layer 50 is provided on the second surface 107. The pad 10 is connected to the substrate 100 through a via hole ( Figure 3 The first via hole 104 in the substrate 100 is connected to the sixth conductive layer 50, and the sixth conductive layer 50 is connected to the sixth conductive layer 50 through the via hole ( Figure 3 The second via hole 105 is connected to the first conductive layer 31.

[0047] In the above scheme, the thickness of the second conductive layer 11 in the direction perpendicular to the substrate 100 is the same as the thickness of the transition film layer 21 in the direction perpendicular to the substrate 100. Therefore, after the third conductive layer 13 is provided on the second conductive layer 11, the thickness of the pad 10 in the direction perpendicular to the substrate 100 will be greater than the thickness of the transition structure in the direction perpendicular to the substrate 100.

[0048] In some implementations of this embodiment, the materials of the first conductive layer 31 and the second conductive layer 11 both include copper, and the material of the third conductive layer 13 includes at least one of gold, nickel, and a gold-nickel alloy, but is not limited thereto.

[0049] The third conductive layer 13 protects the second conductive layer 11 and prevents the second conductive layer 11 from being exposed and oxidized.

[0050] In some implementations of this embodiment, the thickness of the transition film layer 21 is 10-12 um, but is not limited thereto.

[0051] In this embodiment, the thickness of the third conductive layer 13 can be 5-10 μm to ensure that when the flexible circuit board is bound and connected to the display panel, the pad 10 does not contact the edge area of the display panel and the transition structure does not contact the edge area of the display panel.

[0052] refer to Figure 4 and Figure 7In some implementations of this embodiment, along a direction away from the first surface 106 of the substrate 100, the main region 101 is sequentially provided with a first conductive layer 31 and a first covering layer 40, the pad 10 includes a second conductive layer 11 and a third conductive layer 13 sequentially provided, and the transition structure includes a fourth conductive layer 22 and a transition film layer 21;

[0053] The first conductive layer 31 , the second conductive layer 11 and the fourth conductive layer 22 are provided in the same layer.

[0054] The first conductive layer 31, the second conductive layer 11 and the fourth conductive layer 22 are arranged in the same layer and are arranged as a whole on the first surface 106 of the substrate 100, and are integrally formed to simplify the process steps. In this embodiment, the thickness of the transition film layer 21 in the direction perpendicular to the substrate 100 is smaller than the thickness of the third conductive layer 13 in the direction perpendicular to the substrate 100, so that the thickness of the pad 10 in the direction perpendicular to the substrate 100 is greater than the thickness of the transition structure in the direction perpendicular to the substrate 100.

[0055] In a specific implementation of this embodiment, the thickness of the transition film layer 21 is 10-12 um, and the thickness of the third conductive layer 13 is 15-20 um, but the present invention is not limited thereto.

[0056] In a specific implementation of this embodiment, the materials of the first conductive layer 31, the second conductive layer 11 and the fourth conductive layer 22 all include copper, and the material of the third conductive layer 13 includes at least one of gold, nickel and gold-nickel alloy, but is not limited thereto.

[0057] refer to Figure 5 In some implementations of this embodiment, along a direction away from the first surface 106 of the substrate 100, the main region 101 is sequentially provided with a first conductive layer 31 and a first cover layer 40, the pad 10 includes a second conductive layer 11, a fifth conductive layer 12, and a third conductive layer 13 sequentially provided, and the transition structure includes a fourth conductive layer 22 and a transition film layer 21;

[0058] The first conductive layer 31 , the second conductive layer 11 and the fourth conductive layer 22 are arranged on the same layer.

[0059] Relative to Figure 4 The structure of the flexible circuit board shown in Figure 5The pad 10 shown in FIG has a three-layer structure. Since the third conductive layer 13 is made of gold, nickel, or a gold-nickel alloy, and its main function is to prevent oxidation of the copper forming the second conductive layer 11, the thickness of the third conductive layer 13 in the direction perpendicular to the substrate 100 is too thick, which affects the quality of the bonding connection. Figure 5 The pad 10 shown has a three-layer structure. Figure 4 The solder pad 10 shown has a fifth conductive layer 12 added between the second conductive layer 11 and the third conductive layer 13. The fifth conductive layer 12 is formed on the second conductive layer 11 by copper plating. The setting of the fifth conductive layer 12 can ensure that the thickness of the solder pad 10 in the direction perpendicular to the substrate 100 is greater than the thickness of the transition structure in the direction perpendicular to the substrate 100, and reduce the thickness of the third conductive layer 13 to ensure the quality of the binding connection.

[0060] In a specific implementation of this embodiment, the thickness of the transition structure is 10-12 um, and the difference between the thickness of the pad 10 and the thickness of the transition structure is 8-10 um, but the present invention is not limited thereto.

[0061] The thickness of the transition film layer 21, the third conductive layer 13 and the fifth conductive layer 12 can be set according to actual needs. The side of the fifth conductive layer 12 away from the substrate 100 may be flush with the side of the transition film layer 21 away from the substrate 100, or may not be flush, that is, the thickness of the fifth conductive layer 12 in the direction perpendicular to the substrate 100 may be equal to or not equal to the thickness of the transition film layer 21 in the direction perpendicular to the substrate 100. In one embodiment, the thickness of the second conductive layer 11 may be 10-12um, and the thickness of the fifth conductive layer 12 may be 4-5um.

[0062] In some implementations of this embodiment, the materials of the first conductive layer 31, the second conductive layer 11, the fourth conductive layer 22 and the fifth conductive layer 12 all include copper, and the material of the third conductive layer 13 includes at least one of gold, nickel and gold-nickel alloy, but is not limited thereto.

[0063] refer to Figure 4 and Figure 5 In some implementations of this embodiment, a sixth conductive layer 50 is provided on the second surface 107 of the substrate 100 opposite to the first surface 106, the sixth conductive layer 50 is located on the main area 101, and a second covering layer 60 is provided on the side of the sixth conductive layer 50 away from the substrate 100.

[0064] In some implementations of this embodiment, a reinforcement layer 70 is disposed on the second surface 107 of the substrate 100 in the first binding area 103 .

[0065] The reinforcement layer 70 enhances the strength of the pad 10 and prevents the pad 10 from breaking.

[0066] On the second surface 107 of the substrate 100, no other structures are provided in the transition zone 102, that is, on the second surface 107, the reinforcing layer 70 and the sixth conductive layer 50 are arranged at intervals, and in the transition zone 102, a transition structure is provided only on the first surface 106 of the substrate 100 to facilitate bending of the flexible circuit board.

[0067] In some implementations of this embodiment, the first covering layer 40 is connected to the first conductive layer 31 through an adhesive layer 200, the second covering layer 60 is connected to the sixth conductive layer 50 through an adhesive layer 200, and the reinforcement layer 70 is connected to the substrate 100 through an adhesive layer 200. The adhesive layer 200 can be a double-sided tape, but is not limited to this.

[0068] In some implementations of this embodiment, the first covering layer 40 and the second covering layer 60 are made of polyimide film layers, but the present invention is not limited thereto.

[0069] In some implementations of this embodiment, the reinforcement layer 70 may be a polyimide film layer, but is not limited thereto.

[0070] refer to Figure 2 and Figure 7 This embodiment further provides a display module, comprising a display panel 2 and the above-mentioned flexible circuit board 1, wherein the display panel 2 comprises a display area and a second binding area and an edge area 21 sequentially arranged on one side of the display area along a first direction;

[0071] The second binding area is provided with a pad 10 that is bound and connected to the pad 10 of the flexible circuit board. The orthographic projection of at least part of the transition structure on the display panel is located on the edge area 21 .

[0072] refer to Figure 2 and Figure 7 ( Figure 2 and Figure 7Only the structure of the first surface 106 of the substrate is shown in the figure). Since the thickness of the pad 10 in the direction perpendicular to the substrate 100 is greater than the thickness of the transition structure in the direction perpendicular to the substrate 100, when the flexible circuit board 1 is bound to the display panel 2, at least part of the positive projection of the transition structure 20 on the display panel 2 is located on the edge area 21. This can avoid the occurrence of a short circuit between the flexible circuit board 1 and the display panel 2 caused by carbides in the edge area 21.

[0073] Figure 6 The structure diagram of a large-size AMOLED product is shown. The display panel 2 is rectangular, and its long side is the source driving direction. A plurality of source driver ICs 201 are distributed along the long side of the second binding area of the display panel 2. A plurality of source traces (data lines) connected to the plurality of source driver ICs 201 are distributed in the display panel 2. Figure 6 It is just a schematic diagram, each source driver IC 201 is connected to multiple data lines), and the display module also includes multiple flexible circuit boards 1 bound and connected to the multiple source driver ICs 201 in a one-to-one correspondence.

[0074] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A flexible circuit board for connecting a display panel, the flexible circuit board comprising a substrate, characterized in that: include: Main area; A first binding area is provided at one end of the main body area, and a pad is provided in the first binding area; There is a transition area between the first binding area and the main body area, and the transition area is provided with a transition structure, wherein, The pad and the transition structure are both located on the first surface of the substrate, and the thickness of the transition structure in a direction perpendicular to the substrate is smaller than the thickness of the pad in a direction perpendicular to the substrate; Along a direction away from the first surface of the substrate, the main area is sequentially provided with a first conductive layer and a first covering layer, the pad includes a second conductive layer and a third conductive layer sequentially provided, and the transition structure includes a transition film layer provided on the substrate; The material of the second conductive layer includes copper, and the material of the third conductive layer includes at least one of gold, nickel and gold-nickel alloy; The end portion where the transition structure meets the pad is arranged in a wave shape; The thickness of the second conductive layer in a direction perpendicular to the substrate is the same as the thickness of the transition film layer in a direction perpendicular to the substrate; The substrate has a second surface opposite to the first surface, a sixth conductive layer is provided on the second surface, the pad is connected to the sixth conductive layer through a via provided on the substrate, and the sixth conductive layer is connected to the first conductive layer through the via on the substrate.

2. The flexible circuit board according to claim 1, characterized in that: Along a direction away from the first surface of the substrate, the main area is sequentially provided with a first conductive layer and a first covering layer, the pad includes a second conductive layer and a third conductive layer sequentially provided, and the transition structure includes a fourth conductive layer and a transition film layer; The first conductive layer, the second conductive layer and the fourth conductive layer are arranged on the same layer.

3. The flexible circuit board according to claim 2, characterized in that: The material of the fourth conductive layer includes copper.

4. The flexible circuit board according to claim 1, wherein: Along a direction away from the first surface of the substrate, the main area is sequentially provided with a first conductive layer and a first covering layer, the pad includes a second conductive layer, a fifth conductive layer and a third conductive layer that are sequentially provided, and the transition structure includes a fourth conductive layer and a transition film layer; The first conductive layer, the second conductive layer and the fourth conductive layer are arranged on the same layer.

5. The flexible circuit board according to claim 4, characterized in that: Materials of the fourth conductive layer and the fifth conductive layer both include copper.

6. The flexible circuit board according to any one of claims 2 to 4, characterized in that: The materials of the first conductive layer and the second conductive layer both include copper, and the material of the third conductive layer includes at least one of gold, nickel, and a gold-nickel alloy.

7. The flexible circuit board according to any one of claims 2 to 4, characterized in that: The thickness of the transition structure is 10-12 um, and the difference between the thickness of the pad and the thickness of the transition structure is 8-10 um.

8. The flexible circuit board according to any one of claims 1 to 4, characterized in that: A sixth conductive layer is provided on a second surface of the substrate opposite to the first surface. The sixth conductive layer is located on the main region. A second covering layer is provided on a side of the sixth conductive layer away from the substrate.

9. The flexible circuit board according to claim 7, characterized in that: In the first binding area, a reinforcement layer is provided on the second surface of the substrate.

10. A display module comprising a display panel and the flexible circuit board according to any one of claims 1 to 9, wherein the display panel comprises a display area, a second binding area, and an edge area that are adjacently arranged; The second binding area is provided with a pad that is bound and connected to the pad of the flexible circuit board, and at least a portion of the orthographic projection of the transition structure on the display panel is located on the edge area.

Images