Flexible circuit board, cof module, and electronic device comprising same

Abstract

A flexible circuit board according to an embodiment comprises: a substrate including an effective region cut on the basis of a cutting line and including a first side end of the effective region and a second side end of the effective region opposite to the first side end; a conductive pattern part disposed on the substrate and including a pad disposed adjacent to the first side end and the second side end; and a protective layer disposed on the conductive pattern part, wherein a first length of the substrate between the first side end and the second side end of the substrate is 35 mm or less, and a thickness of the substrate is 25 um or less.

Description

Flexible circuit board, COF module, and electronic device including the same

[0001] The embodiment relates to a flexible circuit board, a COF module, and an electronic device including the same.

[0002] Recently, various electronic products are becoming thinner and smaller. Accordingly, it is required to mount semiconductor chips at high density in a narrow area of ​​the electronic products.

[0003] A COF (Chip On Film) comprises a circuit board and a chip disposed on the circuit board. The circuit board is flexible. That is, the COF is a flexible circuit board. Accordingly, the COF is applied to flexible displays. For example, the COF can be applied to various wearable electronic devices. Additionally, the COF has a fine pitch, and accordingly, the COF is applied to displays having high resolution.

[0004] The chip includes semiconductor chips. For example, the chip may be an Integrated Circuit (IC) chip or a Large Scale Integrated Circuit (LSI) chip.

[0005] The chip is connected to an external circuit board and a display panel through a circuit pattern. For example, a pad is provided at each end of the circuit pattern. One pad is electrically connected to a terminal of the chip. The other pad is connected to a terminal of the external circuit board and the display panel. Accordingly, the chip, the external circuit board, and the display panel are electrically connected through the COF. As a result, a signal is transmitted to the display panel through the circuit pattern.

[0006] Recently, display panel specifications have become higher in resolution and higher in integration, and accordingly, a plurality of flexible circuit boards spaced apart from each other in one direction can be attached to a single display panel. For example, in the case of a tablet, about six flexible circuit boards can be combined between the display panel and the external circuit board.

[0007] The aforementioned flexible circuit board can be joined between a display panel and an external circuit board in a bent state. At this time, a springback phenomenon may occur in which the flexible circuit board attempts to return to its original state from the bent state. The aforementioned springback phenomenon may act as a factor that degrades the electrical reliability between the flexible circuit board and the display panel or the external circuit board.

[0008] Accordingly, a structure capable of minimizing the springback phenomenon of flexible circuit boards is required.

[0009] An embodiment provides a flexible circuit board capable of maintaining a stable bending state, a COF module, and an electronic device including the same.

[0010] Additionally, the embodiment provides a flexible circuit board having a springback size of less than or equal to a certain level, a COF module, and an electronic device including the same.

[0011] In addition, the embodiment provides a flexible circuit board, a COF module, and an electronic device including the same, with improved physical reliability and / or electrical reliability.

[0012] Additionally, the embodiment provides a flexible circuit board capable of reducing the size of the bezel area, a COF module, and an electronic device including the same.

[0013] The technical problems to be solved in the proposed embodiments are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the proposed embodiments belong from the description below.

[0014] A flexible circuit board according to an embodiment comprises: a substrate including an effective area that is cut along a cutting line, a first side end of the effective area and a second side end of the effective area opposite to the first side end; a conductive pattern portion disposed on the substrate and including a pad disposed adjacent to the first side end and the second side end; and a protective layer disposed on the conductive pattern portion, wherein the first length of the substrate between the first side end and the second side end of the substrate is 35 mm or less, and the thickness of the substrate is 25 μm or less.

[0015] In addition, the first length of the above-described material between the first side end and the second side end is 30 mm or less, and the thickness of the above-described material is 20 μm or less.

[0016] In addition, the above-mentioned material has a bending region, and the second length from the second side end of the above-mentioned material to the bending region is 15 mm or less.

[0017] In addition, the second length from the second side end of the above-described material to the bending region is 10 mm or less, and the thickness of the above-described material is 20 μm or less.

[0018] Additionally, the conductive pattern portion comprises an upper wiring layer disposed on the substrate, a first upper plating layer disposed on the upper wiring layer, and a second upper plating layer disposed on the first upper plating layer within an area corresponding to the pad, wherein the first upper plating layer comprises an open portion, and the protective layer comprises a first protective pattern disposed within the open portion of the first upper plating layer, and a second protective pattern disposed on the first upper plating layer and the first protective pattern.

[0019] In addition, the second length from the second side end to the first protection pattern is 15 mm or less.

[0020] In addition, the second length from the second side end to the first protection pattern is 10 mm or less, and the thickness of the substrate is 20 μm or less.

[0021] Meanwhile, the COF module according to the embodiment includes the flexible circuit board, and a chip is disposed on the flexible circuit board.

[0022] Additionally, the electronic device according to the embodiment includes the COF module; a circuit board coupled to the first side end of the flexible circuit board; and a display panel coupled to the second side of the flexible circuit board, wherein a plurality of COF modules are provided between the circuit board and the display panel.

[0023] A flexible circuit board according to an embodiment comprises: a substrate having one side and another side opposite to the one side; an upper wiring pattern disposed on the one side of the substrate; an upper protective layer disposed on the upper wiring pattern; a lower wiring pattern disposed under the other side of the substrate; and a lower protective layer disposed under the lower wiring pattern, wherein the substrate comprises an effective area that is cut along a cutting line, and the substrate comprises a first side end of the effective area and a second side end of the effective area opposite to the first side end, and at least one of the upper wiring pattern and the lower wiring pattern comprises a pad disposed on one side or the other side of the effective area adjacent to the first side end and the second side end, and the first length of the substrate between the first side end and the second side end of the substrate is 35 mm or less, and the thickness of the substrate is 25 μm or less.

[0024] In addition, the first length is 15 mm to 35 mm, and the thickness of the substrate is 10 μm to 25 μm.

[0025] In addition, the first length is 30 mm or less, and the thickness of the substrate is 20 μm or less.

[0026] In addition, the above-mentioned material has a bending region, and the second length from the second side end of the above-mentioned material to the bending region is 15 mm or less.

[0027] In addition, the second length from the second side end of the above-described material to the bending region is 10 mm or less, and the thickness of the above-described material is 20 μm or less.

[0028] Additionally, the upper protective layer comprises at least one open area overlapping with the pad along the thickness direction of the substrate, and the upper wiring pattern comprises an upper wiring layer disposed on one side of the substrate, a first upper plating layer disposed on the upper wiring layer, and a second upper plating layer disposed on the first upper plating layer within the open area, and the lower wiring pattern comprises a lower wiring layer disposed under the other side of the substrate, and a lower plating layer disposed under the lower wiring layer.

[0029] Additionally, the first upper plating layer includes an open portion that overlaps with at least a portion of the upper wiring layer along the thickness direction of the substrate, and the upper protective layer includes a first protective pattern disposed within the open portion of the first upper plating layer, and a second protective pattern disposed on the first upper plating layer and the first protective pattern.

[0030] In addition, the first protection pattern is positioned closer to the second side end than to the first side end, and the second length from the second side end to the first protection pattern is 15 mm or less.

[0031] In addition, the second length from the second side end to the first protection pattern is 10 mm or less, and the thickness of the substrate is 20 μm or less.

[0032] A COF module according to an embodiment includes the flexible circuit board, and a chip is disposed on the flexible circuit board.

[0033] Additionally, the electronic device according to the embodiment includes the COF module; a circuit board coupled to a pad disposed adjacent to the first side end of the flexible circuit board; and a display panel coupled to a pad disposed adjacent to the second side end of the flexible circuit board, wherein a plurality of COF modules are provided between the circuit board and the display panel.

[0034] The flexible circuit board of the embodiment includes a substrate. The substrate includes a first side end and a second side end opposite to the first side end. The distance between the first side end and the second side end of the substrate may have a first length. At this time, the first length may be 35 mm or less. At this time, if the first length of the substrate exceeds 35 mm, the width of the bezel area, which increases proportionally to the first length of the substrate, may increase. For example, the flexible circuit board of the embodiment is coupled to a display panel. At this time, while the flexible circuit board is coupled to the display panel, the flexible circuit board may protrude outward from one side of the display panel. The aforementioned protruding area functions as a bezel area where an effective area is not displayed in the electronic device. At this time, if the first length of the substrate exceeds 35 mm, the size of the aforementioned bezel area increases, and as a result, the size of the electronic device may increase.

[0035] Furthermore, the flexible circuit board includes a first protection pattern disposed in a bending area of ​​the substrate. At this time, the distance from the second side end of the substrate to the first protection pattern of the protection layer may have a second length. The aforementioned second length may refer to the length of the flexible circuit board in a bending state. For example, the second length of the substrate may refer to the length from the second side end of the substrate to the point where the bending of the substrate begins. For example, the second length of the substrate may refer to the length from the second side end of the substrate to the first protection pattern. At this time, the aforementioned second length may be 15 mm or less. If the aforementioned second length exceeds 15 mm, the first length of the substrate may increase accordingly.

[0036] The embodiment reduces the thickness of the substrate according to the first length and the second length of the substrate. By doing so, the springback size that increases according to the first length and the second length of the substrate is minimized. That is, when the first length of the substrate is 35 mm or less, or the second length of the substrate is 15 mm or less, the thickness of the substrate is 25 μm or less.

[0037] At this time, if the thickness of the substrate exceeds 25㎛, stress may be applied to the electrical or physical connection sites while the flexible circuit board is bonded to the display panel, and this may cause cracks to occur in the electrical or physical connection sites. Furthermore, if the aforementioned cracks occur, physical reliability and / or electrical reliability may be degraded. Specifically, the flexible circuit board is bonded to the display panel and the external circuit board while in a bent state, and a springback phenomenon may occur in which it attempts to return to its original state from the aforementioned bonded state. Additionally, due to the aforementioned springback phenomenon, stress is applied to the electrical or physical connection sites, which may lead to a decrease in physical reliability and / or electrical reliability.

[0038] Accordingly, in the embodiment, when the first length of the substrate is 35 mm or less and the second length of the substrate is 15 mm or less, the thickness of the substrate is reduced to 25 μm or less, and the springback size is reduced accordingly. Through this, the embodiment can prevent the springback phenomenon and further minimize the springback size. Accordingly, the embodiment can ensure that the flexible circuit board is stably connected to a display panel or an external circuit board, and thereby improve physical reliability and / or electrical reliability. Accordingly, the embodiment can ensure that the flexible circuit board operates more stably, and thereby further improve product reliability.

[0039] FIGS. 1a and FIGS. 1b are schematic plan views of a flexible circuit board according to a first embodiment.

[0040] FIG. 2 is a cross-sectional view of a wiring pattern section cut along one region (A1) of FIG. 1b.

[0041] FIG. 3 is a cross-sectional view of a flexible circuit board according to a second embodiment cut along A-A' of FIG. 1b.

[0042] FIG. 4 is a cross-sectional view of a flexible circuit board according to a third embodiment cut along A-A' of FIG. 1b.

[0043] FIG. 5 is a plan view showing an electronic device in which a COF module, a circuit board, and a display panel are combined in an embodiment.

[0044] FIG. 6 is a diagram illustrating the connection relationship between a COF module, a circuit board, and a display panel according to a first embodiment.

[0045] FIG. 7 is a diagram illustrating the connection relationship between a COF module, a circuit board, and a display panel according to a second embodiment.

[0046] FIG. 8 is a drawing illustrating a comparison of connection relationships according to a comparative example and an embodiment.

[0047] Figure 9 is a drawing illustrating the springback size according to the length of the substrate.

[0048] FIGS. 10 to 12 are drawings relating to an electronic device including a flexible circuit board according to an embodiment.

[0049] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to some of the described embodiments but can be implemented in various different forms, and within the scope of the technical concept of the present invention, one or more of the components among the embodiments may be selectively combined or substituted.

[0050] In addition, terms used in the embodiments of the present invention (including technical and scientific terms) may be interpreted in a sense that is generally understood by those skilled in the art to which the present invention belongs, unless explicitly and specifically defined otherwise. Terms that are commonly used, such as terms defined in advance, may be interpreted in consideration of their meaning in the context of the relevant technology.

[0051] Furthermore, the terms used in the embodiments of the present invention are for the purpose of describing the embodiments and are not intended to limit the present invention. In this specification, the singular form may include the plural form unless specifically stated otherwise in the text, and when described as “and at least one of B and C (or more than one),” it may include one or more of all combinations that can be formed from A, B, and C.

[0052] In addition, terms such as first, second, A, B, (a), (b), etc., may be used when describing the components of the embodiments of the present invention. These terms are used merely to distinguish the components from other components and are not intended to limit the essence, order, or sequence of the components.

[0053] And, where it is stated that a component is 'connected', 'combined', or 'joined' to another component, this may include not only cases where the component is directly connected, combined, or joined to the other component, but also cases where it is 'connected', 'combined', or 'joined' due to another component located between the component and the other component.

[0054] Additionally, where described as being formed or placed on the "top or bottom" of each component, the top or bottom includes not only cases where two components are in direct contact with each other, but also cases where one or more other components are formed or placed between the two components.

[0055] In addition, when expressed as “up” or “down,” it can include the meaning of a downward direction as well as an upward direction relative to a single component.

[0056]

[0057] Hereinafter, with reference to the drawings, a flexible circuit board according to an embodiment and a COF module including the same will be described.

[0058]

[0059] FIGS. 1a and 1b are schematic plan views of a flexible circuit board according to a first embodiment. Specifically, FIG. 1a is a schematic plan view of one side of a flexible circuit board according to a first embodiment with a protective layer removed, and FIG. 1b is a schematic plan view of one side of a flexible circuit board according to a first embodiment with a protective layer disposed thereon.

[0060] Referring to FIG. 1a and FIG. 1b, a flexible circuit board (1000) according to the first embodiment includes a substrate (100), a conductive pattern portion (WP, DP), and a protective layer (800).

[0061] The substrate (100) includes one surface and another surface opposite to the one surface. At this time, the one surface of the substrate (100) may refer to the upper surface of the substrate (100) on which the conductive pattern portion (CP, DP) and the protective layer (800) are placed. The other surface of the substrate (100) may refer to the lower surface of the substrate (100).

[0062] A conductive pattern portion (WP, DP) and a protective layer (800) are disposed on one side of the substrate (100).

[0063] The substrate (100) may not represent the final manufactured flexible circuit board (1000). For example, the final manufactured flexible circuit board (1000) may not include some areas of the substrate (100) shown in FIG. 1a and FIG. 1b. For example, some areas of the substrate (100) shown in FIG. 1a and FIG. 1b may be cut and removed along a cutting line.

[0064] For example, a conductive pattern portion (WP, DP), a protective layer (800), and a chip (not shown) are disposed on a substrate (100). Subsequently, the substrate (100) can be cut along a cutting line, and a COF module can be manufactured accordingly. Here, the cutting line may correspond to a line defining an effective area (AA). Specifically, the finally manufactured flexible circuit board (1000) can be cut using a line separating the effective area (AA) shown in FIG. 1a and FIG. 1b as the cutting line.

[0065] Accordingly, the perimeter of the final manufactured COF module may correspond to the perimeter of the effective area (AA) of the substrate (100) in FIG. 1a and FIG. 1b. Additionally, a conductive pattern portion (WP, DP) and a protective layer (800) may be provided on the substrate (100) outside the effective area (AA) (preferably, in the non-effective area (UA)). At this time, the conductive pattern portion provided in the non-effective area (UA) may function as a test pattern for testing the signal lines of the conductive pattern portion (WP, DP) provided in the effective area (AA), or as a dummy pattern for improving the rigidity of the flexible circuit board (1000).

[0066] The substrate (100) includes an effective area (AA) and a non-effective area (UA). Specifically, one side of the substrate (100) includes an effective area (AA) and a non-effective area (UA) excluding the effective area (AA).

[0067] The valid area (AA) and the invalid area (UA) are separated by a cutting line. The valid area (AA) is the inner region of the area separated by the cutting line. Additionally, the invalid area (UA) is the outer region of the area separated by the cutting line.

[0068] A conductive pattern portion (WP, DP), a protective layer (800), and a chip (not shown) may be disposed on the effective area (AA). Additionally, a conductive pattern portion (not shown) and a sprocket hole (SH) may be provided on the non-effective area (UA). The wiring pattern of the conductive pattern portion provided on the non-effective area (UA) may be a test pattern for testing the wiring pattern portion (200) disposed on the effective area (AA). Furthermore, the dummy pattern of the conductive pattern portion provided on the non-effective area (UA) increases the strength of the substrate (100).

[0069] Additionally, the flexible circuit board (1000) can be manufactured by winding or unwinding it in a roll-to-roll manner through the sprocket hole (SH).

[0070] The substrate (100) includes a chip mounting area (CHA). The chip mounting area (CHA) may be provided on one side of the substrate (100). The chip mounting area (CHA) may be located in an effective area (AA) of the substrate (100). A chip (not shown) may be mounted on the chip mounting area (CHA). At this time, the pads of the conductive pattern portions (WP, DP) may be located within the chip mounting area (CHA).

[0071] The protective layer (800) may not be placed on the chip mounting area (CHA). For example, the protective layer (800) may include a first open area (OR1) that overlaps along a vertical direction with respect to the chip mounting area (CHA). The planar area of ​​the first open area (OR1) of the protective layer (800) may be larger than the planar area of ​​the chip mounting area (CHA). For example, the perimeter of the inner surface of the first open area (OR1) of the protective layer (800) may be provided to surround the chip mounting area (CHA) at a position spaced apart from the chip mounting area (CHA). Through this, process characteristics in the process of mounting a chip in the chip mounting area (CHA) can be improved, and the chip can be mounted more stably.

[0072] The protective layer (800) may further include a second open area (OR2) and a third open area (OR3). That is, the substrate (100) may include a substrate connection area (not shown) to which an external circuit board is connected. Additionally, the substrate (100) may include a panel connection area (not shown) to which a display panel is connected. For example, the substrate (100) may include a first side end (100E1) and a second side end (100E2) facing in a first direction (1D). Furthermore, the substrate (100) may include a substrate area provided in an area adjacent to the first side end (100E1). Additionally, the substrate (100) may include a panel connection area provided in an area adjacent to the second side end (100E2).

[0073] The protective layer (800) may not be placed on the substrate connection area. That is, the protective layer (800) may include a second open area (OR2) that overlaps along the vertical direction with the substrate connection area. Additionally, the protective layer (800) may not be placed on the panel connection area. That is, the protective layer (800) may include a third open area (OR3) that overlaps along the vertical direction with the panel connection area.

[0074] The substrate (100) comprises a flexible material. For example, the substrate (100) may comprise polyimide (PI). However, the embodiments are not limited thereto. The substrate (100) may comprise a polymer material including polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). Accordingly, the flexible circuit board (1000) can be applied to various electronic devices including curved display devices.

[0075] The substrate (100) may have a first length (L1) in a first direction (1D). For example, the substrate (100) may include a first side end (100E1) and a second side end (100E2), and the length between the first side end (100E1) and the second side end (100E2) may be the first length (L1). Here, the first side end (100E1) may refer to the first side end of the effective area (AA) of the substrate (100). Specifically, the first side end (100E1) may refer to a first cut side end cut along a cutting line. Additionally, the second side end (100E2) may refer to the second side end of the effective area (AA) of the substrate (100) opposite to the first side end (100E1). Specifically, the second side end (100E2) may refer to a second cut side end cut along a cutting line. Additionally, the first length (L1) may refer to the length in the first direction (1D) of the effective area (AA) of the substrate (100).

[0076] At this time, the first length (L1) of the substrate (100) may be 35 mm or less. Preferably, the first length (L1) of the substrate (100) may be 30 mm or less. More preferably, the first length (L1) of the substrate (100) may be 25 mm.

[0077] For example, the first length (L1) of the substrate (100) may be 15 mm to 35 mm. For example, the first length (L1) of the substrate (100) may be 15 mm to 30 mm. For example, the first length (L1) of the substrate (100) may be 15 mm to 25 mm.

[0078] If the first length (L1) of the substrate (100) exceeds 35 mm, the width of the bezel area, which increases proportionally to the first length (L1) of the substrate (100), may increase. For example, the flexible circuit board of the embodiment is coupled to a display panel. At this time, while the flexible circuit board is coupled to the display panel, the flexible circuit board may protrude outward from one side of the display panel. The protruding area described above functions as a bezel area where an effective area is not displayed in the electronic device. At this time, if the first length (L1) of the substrate (100) exceeds 35 mm, the size of the bezel area described above increases, and as a result, the size of the electronic device may increase.

[0079] In addition, if the first length (L1) is less than 15 mm, it may be difficult to place all the conductive pattern portions (WP, DP) connected to the display panel, chip, and external circuit board within the limited space.

[0080] The thickness of the substrate (100) may be 25㎛ or less. Preferably, the thickness of the substrate (100) may be 23㎛ or less. More preferably, the thickness of the substrate (100) may be 20㎛ or less.

[0081] If the thickness of the substrate (100) exceeds 25㎛, stress may be applied to the electrical connection area or the physical connection area while the flexible circuit board is bonded to the display panel, and as a result, cracks may occur in the electrical connection area or the physical connection area. In addition, if the above-mentioned cracks occur, physical reliability and / or electrical reliability may be reduced.

[0082] Specifically, the flexible circuit board is coupled to a display panel and an external circuit board while in a bent state, and a springback phenomenon may occur in which it attempts to return to its original state from the aforementioned coupled state. Furthermore, due to the aforementioned springback phenomenon, stress is applied to the electrical or physical coupling parts, which may degrade physical reliability and / or electrical reliability.

[0083] Furthermore, the first length (L1) of the substrate (100) is reduced and, as described above, can be 35 mm or less. And, when the first length (L1) of the substrate (100) is reduced, the springback size occurring under the same conditions may increase further. Accordingly, the embodiment reduces the thickness of the substrate (100) to 25 μm or less as the first length (L1) of the substrate (100) is 35 mm, and thereby reduces the springback size. Through this, the embodiment can prevent the springback phenomenon and further minimize the springback size. Accordingly, the embodiment can ensure that the flexible circuit board is stably connected to a display panel or an external circuit board, and thereby improve physical reliability and / or electrical reliability. Accordingly, the embodiment can ensure that the flexible circuit board operates more stably and thereby further improve product reliability.

[0084] Additionally, the thickness of the substrate (100) may be 10 μm or more. Preferably, the thickness of the substrate (100) may be 12 μm or more. More preferably, the thickness of the substrate (100) may be 15 μm or more. If the thickness of the substrate (100) is less than 10 μm, processability in the manufacturing process of the flexible circuit board may be reduced. For example, the flexible circuit board is manufactured through a roll-to-roll process. At this time, in order to secure the flatness of the substrate (100) in the manufacturing process of the flexible circuit board, a tension of a certain level or more is applied to the substrate (100). Here, if the thickness of the substrate (100) is less than 10 μm, the magnitude of the applied tension may be reduced, and as a result, the flatness of the substrate (100) may be reduced. Also, if the thickness of the substrate (100) is less than 10 μm, a problem may occur in which the substrate (100) tears due to the applied tension.

[0085] The relationship between the thickness of the substrate (100) according to the first length (L1) of the above-described substrate (100) is explained in more detail below.

[0086] A conductive pattern portion (WP, DP) and a protective layer (800) are disposed on a substrate (100). A conductive pattern portion (CP), a circuit pattern, and a protective layer (800) are disposed on one side of the substrate (100). For example, the conductive pattern portion (WP, DP) and the protective layer (800) may be disposed on an effective area (AA) of the substrate (100). Additionally, the conductive pattern portion (WP, DP) and the protective layer (800) may be optionally disposed on an ineffective area (UA) of the substrate (100).

[0087] The conductive pattern section (WP, DP) may include a wiring pattern section (WP) and a dummy pattern section (DP) depending on the function. The wiring pattern section (WP) and the dummy pattern section (DP) may include the same metallic material. The wiring pattern section (WP) and the dummy pattern section (DP) may have the same layer structure. Here, the wiring pattern section (WP) and the dummy pattern section (DP) may be distinguished based on whether an effective signal is transmitted. Alternatively, the wiring pattern section (WP) and the dummy pattern section (DP) may be distinguished based on whether a signal is transmitted and / or received between multiple components.

[0088] The wiring pattern section (WP) may refer to a conductive pattern through which an effective signal is transmitted. Here, the effective signal may include a control signal transmitted to control a specific component, a signal obtained from a specific component, and / or a power signal, etc. Additionally, the wiring pattern section (WP) may refer to a conductive pattern through which a signal is transmitted and / or received between multiple components. For example, the wiring pattern section (WP) may electrically connect a chip and an external circuit board, a chip and a display panel, or an external circuit board and a display panel.

[0089] The dummy pattern section (DP) may refer to a conductive pattern in which no valid signal is transmitted. Alternatively, the dummy pattern section (DP) may refer to a conductive pattern that is not electrically connected between multiple components. For example, the dummy pattern section (DP) may refer to a conductive pattern in which a valid signal (e.g., a test signal, etc.) is transmitted, but which is not electrically connected between the chip and the external circuit board, between the chip and the display panel, or between the external circuit board and the display panel. For example, the dummy pattern section (DP) may be electrically connected to any one of the components among the chip, the external circuit board, and the display panel, but not electrically connected to other components. The dummy pattern section (DP) may refer to a conductive pattern that performs at least one of a test function, a dummy function, a heat dissipation function, and a rigidity reinforcement function.

[0090] At least one of the wiring pattern section (WP) and the dummy pattern section (DP) may include pads disposed within the open area (OR) of the protective layer (800). In this case, the pads disposed within the open area (OR) of the protective layer (800) may be referred to as inner pads. Additionally, at least one of the wiring pattern section (WP) and the dummy pattern section (DP) may include pads disposed between the first side end (800E1) of the protective layer (800) and the first side end (100E1) of the substrate (100) that are not covered by the protective layer (800), and this may be referred to as a first outer pad. Additionally, at least one of the wiring pattern section (WP) and the dummy pattern section (DP) may include pads disposed between the second side end (800E2) of the protective layer (800) and the second side end (100E2) of the substrate (100) that are not covered by the protective layer (800), and this may be referred to as a second outer pad.

[0091] The wiring pattern section (WP) may include a first wiring pattern section (200), a second wiring pattern section (300), and a third wiring pattern section (400) depending on the placement location and / or function.

[0092] One end of the first wiring pattern portion (200) may be located within the first open area (OR1) of the protection layer (800) and the other end may be located within the second open area (OR2) of the protection layer (800). For example, one end of the first wiring pattern portion (200) may be connected to a chip, and the other end of the first wiring pattern portion (200) may be connected to an external circuit board. That is, the first wiring pattern portion (200) may refer to a wiring pattern that electrically connects the chip and the external circuit board. For example, the first wiring pattern portion (200) may include a first pad placed within the first open area (OR1), a second pad placed within the second open area (OR2), and a connecting wire connecting the first pad and the second pad.

[0093] The first wiring pattern section (200) may include a first-1 wiring pattern section (210) and a first-2 wiring pattern section (220) according to the arrangement structure and / or connection structure. The first-1 wiring pattern section (210) may be arranged such that one connecting wire connects between one first pad and one second pad. The first-2 wiring pattern section (220) may be arranged such that one connecting wire connects between a plurality of first pads and / or a plurality of second pads.

[0094] For example, the number of interconnected connecting wires, first pads, and second pads in the first-1 wiring pattern section (210) may be the same. For example, the number of interconnected connecting wires, first pads, and second pads in the first-2 wiring pattern section (220) may be different. For example, in the first-2 wiring section (220), one connection pattern may connect two or more first pads and one second pad. Or, in the first-2 wiring section (220), one connection pattern may connect one first pad and two or more second pads. Or, in the first-2 wiring section (220), one connection pattern may connect two or more first pads and two or more second pads.

[0095] The first-1 wiring pattern section (210) may include a first pad (210P1) disposed within a first open area (OR1). The first pad (210P1) of the first-1 wiring pattern section (210) may be connected to a chip. The first-1 wiring pattern section (210) may include a second pad (210P2) disposed within a second open area (OR2). The second pad (210P2) of the first-1 wiring pattern section (210) may be connected to an external circuit board. The first-1 wiring pattern section (210) may include a first connection pattern (210T) connecting the first pad (210P1) and the second pad (210P2). The first connection pattern (210T) of the first-1 wiring pattern section (210) may be covered by a protective layer (800). At this time, the first connection pattern (210T) of the first-1 wiring pattern section (210) may further include an area not covered by the protective layer (800). For example, the first connection pattern (210T) of the first-1 wiring pattern section (210) may include a first part connected to the first pad (210P1) of the first-1 wiring pattern section (210) and disposed within the first open area (OR1) of the protective layer (800). Additionally, the first connection pattern (210T) of the first-1 wiring pattern section (210) may include a second part connected to the second pad (210P2) of the first-1 wiring pattern section (210) and located within the second open area (OR2) of the protective layer (800).

[0096] Additionally, the first-1 wiring pattern section (210) may include a plurality of first-1 wiring patterns that are spaced apart from each other and arranged on the substrate (100), and include the first pad (210P1), second pad (210P2), and first connection pattern (210T) described above.

[0097] The first-2 wiring pattern section (220) may include a plurality of third pads (220P1) spaced apart from each other and disposed within a first open area (OR1). The plurality of third pads (220P1) of the first-2 wiring pattern section (220) may each be connected to different terminals of the chip. The first-2 wiring pattern section (220) may include a plurality of fourth pads (220P2) disposed within a second open area (OR2). The plurality of fourth pads (220P2) of the first-2 wiring pattern section (220) may be connected to an external circuit board. The first-2 wiring pattern section (220) may include a second connection pattern (220T) connecting the plurality of third pads (220P1) of the first-2 wiring pattern section (220) and the plurality of fourth pads (220P2) of the first-2 wiring pattern section (220). That is, the second connection pattern (220T) of the first-second wiring pattern section (220) may include a plurality of branch lines, at least one of a plurality of one end and a plurality of other ends. Additionally, the plurality of branch lines of the second connection pattern (220T) provided at one end of the first-second wiring pattern section (220) may be connected to a plurality of third pads (220P1) of the first-second wiring pattern section (220). Furthermore, the plurality of branch lines of the second connection pattern (220T) provided at the other end of the first-second wiring pattern section (220) may be connected to a plurality of fourth pads (220P2) of the first-second wiring pattern section (220).

[0098] Additionally, the first-second wiring pattern section (220) may include a plurality of first-second wiring patterns each comprising a second connection pattern (220T) that includes the aforementioned third pad (220P1), fourth pad (220P2), and a plurality of branch lines, which are spaced apart from each other.

[0099] One end of the second wiring pattern section (300) may be located within the first open area (OR1) of the protection layer (800) and the other end may be located within the third open area (OR3) of the protection layer (800). For example, one end of the second wiring pattern section (300) may be connected to a chip, and the other end of the second wiring pattern section (300) may be connected to a display panel. That is, the second wiring pattern section (300) may refer to a wiring pattern that electrically connects the chip and the display panel. For example, the second wiring pattern section (300) may include a fifth pad (310P1, 320P1) placed within the first open area (OR1), a sixth pad (310P2, 320P2) placed within the third open area (OR3), and a third connecting wire (310T, 320T) connecting them.

[0100] The second wiring pattern section (310) may include a second-1 wiring pattern section (310) and a second wiring pattern section (320) depending on the location. The second-1 wiring pattern section (310) may have a fifth pad (310P1) provided on the upper side of the first open area (OR1), and the second-2 wiring pattern section (320) may have a fifth pad (32OP1) provided on the lower side of the first open area (OR1). Additionally, the third connecting wire (310T) of the second-1 wiring pattern section (310) may be positioned on the upper side of the first open area (OR1) toward the second side end (100E2) of the substrate (100) and connected to the sixth pad (310P2) of the second-1 wiring pattern section (310). And, the third connecting wire (320T) of the second-2 wiring pattern section (320) is positioned below the first open area (OR1) while avoiding other wiring patterns or a dummy pattern section (DP) and can be connected to the sixth pad (320P2) of the second-2 wiring pattern section (320).

[0101] One end of the third wiring pattern section (400) may be located within the second open area (OR2) of the protection layer (800) and the other end may be located within the third open area (OR3) of the protection layer (800). For example, one end of the third wiring pattern section (400) may be connected to an external circuit board, and the other end of the third wiring pattern section (400) may be connected to a display panel. That is, the third wiring pattern section (400) may refer to a wiring pattern that electrically connects the external circuit board and the display panel. For example, the third wiring pattern section (400) may include a seventh pad (400P1) placed within the second open area (OR2), an eighth pad (400P2) placed within the third open area (OR3), and a fourth connecting wire (400T) connecting the seventh pad (400P1) and the eighth pad (400P2).

[0102] Additionally, the third wiring pattern section (400) may include a plurality of third wiring patterns spaced apart from each other, each including the aforementioned seventh pad (400P1), eighth pad (400P2), and fourth connecting wire (400T).

[0103] The third wiring pattern section (400) may be a bypass wiring pattern. For example, the third wiring pattern section (400) may be a power wiring line. Accordingly, the external circuit board and the display panel may receive power through the third wiring pattern section (400).

[0104] The line width of the third wiring pattern section (400) may be larger than the line width of the first and second wiring pattern sections (300, 400). This enables stable power supply.

[0105] One end of the first dummy pattern portion (500) may be located in the first open area (OR1), and the other end may be covered by a protective layer (800). For example, one end of the first dummy pattern portion (500) may be connected to a chip, and the other end may not be electrically connected to other components.

[0106] The first dummy pattern section (500) may include a ninth pad (510P, 520P, 530P) disposed within the first open area (OR1), and a fifth connecting wire (510T, 520T, 530T) connected to the ninth pad (510P, 520P, 530P).

[0107] The first dummy pattern section (500) may include a first-1 dummy pattern section (510), a first-2 dummy pattern section (520), and a first-3 dummy pattern section (530) depending on the location.

[0108] The ninth pad (510P) of the first-1 dummy pattern section (510) may be located below the first open area (OR1), and the fifth connecting wire (510T) of the first-1 dummy pattern section (510) may be connected to the ninth pad (510P) and extended in a direction toward the first side end (100E1) of the substrate (100).

[0109] The ninth pad (520P) of the first-second dummy pattern section (520) may be located to the left of the first open area (OR1), and the fifth connecting wire (520T) of the first-second dummy pattern section (520) may be connected to the ninth pad (520P) and extended in a direction toward the left end of the substrate (100).

[0110] The ninth pad (530P) of the first-third dummy pattern section (530) may be located to the right of the first open area (OR1), and the fifth connecting wire (530T) of the first-third dummy pattern section (530) may be connected to the ninth pad (530P) and extended in a direction toward the right end of the substrate (100).

[0111] The first dummy pattern section (500) described above is connected to the chip and can be used to test a specific terminal of the chip or to perform a heat dissipation function to transfer heat generated from the chip.

[0112] One end of the second dummy pattern portion (600) may be located in the second open area (OR2), and the other end may be covered by a protective layer (800). For example, one end of the second dummy pattern portion (600) may be connected to an external circuit board, and the other end may not be electrically connected to other components.

[0113] The second dummy pattern section (600) may include a first pad (610P) disposed within the second open area (OR2), and a sixth connecting wire (610T) connected to the first pad (610P).

[0114] The aforementioned second dummy pattern section (600) is connected to an external circuit board and can be used to test a specific signal line of the external circuit board or can perform a heat dissipation function to transfer heat generated from the external circuit board.

[0115] One end of the third dummy pattern portion (700) may be located in the third open area (OR3), and the other end may be covered by a protective layer (800). For example, one end of the third dummy pattern portion (700) may be connected to an external circuit board, and the other end may not be electrically connected to other components.

[0116] The third dummy pattern section (700) may include a first pad (710P) disposed within the second open area (OR2), and a seventh connecting wire (710T) connected to the first pad (710P).

[0117] The aforementioned third dummy pattern section (700) is connected to a display panel and can be used to test a specific signal line of the display panel or to perform a heat dissipation function to transfer heat generated from the display panel.

[0118] In addition, the aforementioned dummy pattern section (DP) can perform a reinforcing function, thereby preventing the flexible circuit board (1000) from bending. Furthermore, the line width and spacing of the wiring pattern section (WP) can be made uniform by the dummy pattern section (DP).

[0119] The protective layer (800) is disposed on the substrate (100) and may include a plurality of open regions. For example, the protective layer (800) may include a first open region (OR1). The first open region (OR1) may overlap along a vertical direction with the chip mounting region (CHA).

[0120] The protective layer (800) may include a second open area (OR2) and a third open area (OR3). In this case, the second open area (OR2) and the third open area (OR3) may be intentionally formed open areas, or they may be parts formed by not placing the protective layer (800) in the corresponding area.

[0121] For example, the first side end (800E1) of the protective layer (800) may be located further inward than the first side end (100E1) of the substrate (100). Accordingly, a second open area (OR2) may be provided between the first side end (800E1) of the protective layer (800) and the first side end (100E1) of the substrate (100).

[0122] Additionally, the second side end (800E2) of the protective layer (800) may be located further inward than the second side end (100E2) of the substrate (100). Accordingly, a third open area (OR3) may be provided between the second side end (800E2) of the protective layer (800) and the second side end (100E2) of the substrate (100).

[0123]

[0124] FIG. 2 is a cross-sectional view of a wiring pattern section cut along one region (A1) of FIG. 1b.

[0125] The following description is based on the effective area (AA) of the flexible circuit board (1000). Referring to FIG. 2, the flexible circuit board (1000) includes a first area (R1) and a second area (R2). That is, the flexible circuit board (1000) includes an effective area (AA), and the effective area (AA) can be divided into a first area (R1) and a second area (R2).

[0126] The first region (R1) can be defined as the bending region (BA) of the flexible circuit board (1000), and the second region (R2) can be defined as the region excluding the first region (R1). For example, the flexible circuit board (1000) can be bent based on the bending region (BA). Also, the first region (R1) can refer to the bending region (BA) of the flexible circuit board (1000), and the second region (R2) can be defined as the remaining region excluding the bending region (BA).

[0127] A flexible circuit board (1000) includes a substrate (100). An upper wiring pattern (200U) is disposed on a first surface (1S) of the substrate (100). Here, the upper wiring pattern (200U) may represent the wiring pattern portion (200) shown in FIGS. 1a and FIGS. 1b. Preferably, the upper wiring pattern (200U) may represent the second wiring pattern portion (310) shown in FIGS. 1a and FIGS. 1b.

[0128] The upper wiring pattern (200U) may be provided in multiple layers. For example, the upper wiring pattern (200U) may include an upper wiring layer (200a) and an upper plating layer (200b) disposed on the upper wiring layer (200a).

[0129] The upper wiring layer (200a) may be disposed with a thickness of 1 µm to 20 µm. For example, the upper wiring layer (200a) may be disposed with a thickness of 5 µm to 20 µm. For example, the upper wiring layer (200a) may be disposed with a thickness of 5 µm to 15 µm.

[0130] If the thickness of the upper wiring layer (200a) is less than 1 μm, the resistance of the upper wiring layer (200a) may increase. If the thickness of the upper wiring layer (200a) is greater than 20 μm, it may be difficult to implement a fine pattern.

[0131] An upper plating layer (200b) may be disposed on the upper wiring layer (200a). The upper plating layer (200b) may include a first upper plating layer (200b1) and a second upper plating layer (200b2).

[0132] The first upper plating layer (200b1) may be partially disposed on the upper wiring layer (200a). The first upper plating layer (200b1) may be disposed on the second region (R2) excluding the first region (R1) on the upper wiring layer (200a). The first upper plating layer (200b1) may be disposed in an area other than the region where the first protective pattern (810) of the protective layer (800) on the upper wiring layer (200a) is disposed. For example, the first upper plating layer (200b1) may be disposed in the area where the second protective pattern (820) on the upper wiring layer (200a) is disposed.

[0133] That is, the first upper plating layer (200b1) may not be placed on the first region (R1) on the upper wiring layer (200a). Accordingly, the first upper plating layer (200b1) may include an open portion (200b1O) provided in the first region (R1). For example, the width of the open portion (200b1O) may correspond to the width of the first region (R1). Specifically, the side of the first upper plating layer (200b1) may be placed in the boundary region between the first region (R1) and the second region (R1).

[0134] The first upper plating layer (200b1) may be spaced apart from each other by an open portion (200b1O). For example, the first upper plating layer (200b1) at the outer side of one end of the first region (R1) and the first upper plating layer (200b1) at the outer side of the other end of the first region (R1) may not be connected to each other.

[0135] The second upper plating layer (200b2) may be disposed on the first upper plating layer (200b1). The second upper plating layer (200b2) may be partially disposed on the first upper plating layer (200b1).

[0136] The second upper plating layer (200b2) may be disposed in an area other than the area where the second protection pattern (820) of the protection layer (800) is disposed. For example, the protection layer (800) may include a plurality of open areas. The protection layer (800) may include a first open area (OR1), a second open area (OR2), and a third open area (OR3). The first open area (OR1) of the protection layer (800) may correspond to a chip mounting area (CHA1). The second open area (OR2) of the protection layer (800) may be a first connection area connected to an external circuit board.

[0137] And, the second upper plating layer (200b2) can be placed on the first upper plating layer (200b1) on the first open area (OR1), the second open area (OR2), and the third open area (OR3).

[0138] That is, the upper plating layer (200b) may not be disposed in the first region (R1) of the flexible circuit board (1000) of the embodiment. Specifically, the first upper plating layer (200b1) and the second upper plating layer (200b2) may not be disposed in the first region (R1) of the flexible circuit board (1000). By doing so, the embodiment can prevent cracks that occur during bending of the flexible circuit board (1000) in the first region (R1), thereby further improving the physical reliability and / or electrical reliability of the flexible circuit board (1000). Additionally, the embodiment can prevent the upper wiring pattern (200U) from being damaged by the tensile force of the upper wiring pattern (200U) that occurs during bending of the flexible circuit board (1000) in the first region (R1), thereby improving the durability of the upper wiring pattern (200U).

[0139] In this way, the upper plating layer (200b) may be provided in two layers. That is, the upper plating layer (200b) may include a first upper plating layer (200b1) and a second upper plating layer (200b2). The first upper plating layer (200b1) and the second upper plating layer (200b2) may be formed in two layers on the upper wiring layer (200a) to prevent whisker formation. That is, the first upper plating layer (200b1) and the second upper plating layer (200b2) may be placed on the first open area (OR1) and the second open area (OR2) of the protective layer (800). Accordingly, short circuits between the patterns of the upper wiring layer (200a) can be prevented.

[0140] The upper plating layer (200b) may contain tin (Sn). For example, the first upper plating layer (200b1) and the second upper plating layer (200b2) may contain tin (Sn). For example, the upper wiring layer (200a) may contain copper (Cu), and the first upper plating layer (200b1) and the second upper plating layer (200b2) may contain tin (Sn). When the upper plating layer (200b) contains tin, oxidation of the upper wiring layer (200a) in the area where the protective layer (800) is not placed can be prevented because tin (Sn) has excellent corrosion resistance.

[0141] The protective layer (800) may have a two-layer structure including a first protective pattern (810) and a second protective pattern (820).

[0142] The first protection pattern (810) of the protection layer (800) may be provided in the first region (R1) of the flexible circuit board. That is, the first protection pattern (810) of the protection layer (800) may be in direct contact with the upper wiring layer (200a) of the upper wiring pattern (200U). For example, the lower surface of the first protection pattern (810) of the protection layer (800) may be in direct contact with the upper surface of the upper wiring layer (200a) and may not be in contact with the upper plating layer (200b).

[0143] The second protective pattern (820) of the protective layer (800) may be placed on the first protective pattern (810) and the first upper plating layer (200b1). That is, the second protective pattern (820) of the protective layer (800) may be placed in an area excluding the first open area (OR1) and the second open area (OR2).

[0144] Accordingly, on the first surface (1S) of the substrate (100), there may be a first placement area in which an upper wiring layer (200a), a first protection pattern (810), and a second protection pattern (820) are placed, a second placement area in which an upper wiring layer (200a), a first upper plating layer (200b1), and a second protection pattern (820) are placed, and an area in which an upper wiring layer (200a), a first upper plating layer (200b1), and a second upper plating layer (200b1) are placed.

[0145] The structure described above may include a first process of applying a first protective pattern (810) of a protective layer (800) on an upper wiring layer (200a), a second process of plating a first upper plating layer (200b1) with tin (Sn) on the upper wiring layer (200a), a third process of plating a second protective pattern (820) on the first protective pattern (810) and the first upper plating layer (200b1), and a fourth process of plating a second upper plating layer (200b2) with tin (Sn).

[0146] At this time, during the heat treatment process, the copper (Cu) of the upper wiring layer (200a) or the tin (Sn) of the upper plating layer (200b) may undergo diffusion. Accordingly, as the diffusion concentration of copper (Cu) decreases from the first upper plating layer (200b1) toward the surface of the second upper plating layer (200b2), the copper (Cu) content may decrease. Meanwhile, the tin (Sn) content may increase from the first upper plating layer (200b1) toward the surface of the second upper plating layer (200b2).

[0147] Due to chemical reactions at the lamination interface of the upper wiring layer (200a) and the upper plating layer (200b), the first upper plating layer (200b1) and the second upper plating layer (200b2) may be an alloy of tin and copper. Additionally, the tin and copper content of the first upper plating layer (200b1) and the second upper plating layer (200b2) may differ from each other. That is, the first upper plating layer (200b1) in direct contact with the upper wiring layer (200a) may have a higher copper content than the second upper plating layer (200b2). Alternatively, the first upper plating layer (200b1) may be an alloy of tin and copper, and the second upper plating layer (200b2) may contain tin. The plating layer according to the embodiment can prevent electrochemical migration resistance due to the diffusion phenomenon of Cu / Sn, thereby blocking short-circuit defects caused by metal growth.

[0148] However, the embodiments are not limited thereto and may include any one of Ni / Au alloy, gold (Au), electroless nickel immersion gold (ENIG), Ni / Pd alloy, and organic solderability preservative (OSP).

[0149] The first upper plating layer (200b1) may have a different thickness from the second upper plating layer (200b2). The thickness of the first upper plating layer (200b1) may be smaller than the thickness of the second upper plating layer (200b2). For example, the first upper plating layer (200b1) may have a thickness of 0.1 μm or less. For example, the second upper plating layer (200b2) may have a thickness of 1 μm or less. That is, the total thickness of the upper plating layer (200b) may be 1.1 μm or less.

[0150] The protective layer (800) may include a first protective pattern (810) and a second protective pattern (820). The first protective pattern (810) may be placed in a first region (R1), which is a bending region of the upper wiring layer (200a), and the second protective pattern (820) may be placed on the first protective pattern (810).

[0151] The first protection pattern (810) can be in contact with the upper wiring layer (200a) and the first upper plating layer (200b1). The first protection pattern (810) can be in contact with the upper surface of the upper wiring layer (200a) and the side surface of the first upper plating layer (200b1) on the first region (R1).

[0152] That is, the first protection pattern (810) is in direct contact with the upper wiring layer (200a), thereby dispersing the stress that may occur during bending of the first region (R1), and thus further improving the physical reliability and / or electrical reliability of the flexible circuit board. Additionally, the lower surface of the second protection pattern (820) is in contact with the first upper plating layer (200b1) and is not in contact with the second upper plating layer (200b1). Accordingly, it is possible to prevent the thickness of the flexible circuit board from increasing by the thickness of the second upper plating layer (200b2).

[0153] At this time, the second length (L2) from the second side end (110E2) of the substrate (100) to the first protection pattern (810) of the protection layer (800) may have a second length (L2). The second length (L2) described above may be smaller than the first length (L1) of the substrate (100). That is, the second length (L2) of the substrate (100) may refer to the length of the flexible circuit board (1000) in a bending state. For example, the second length (L2) of the substrate (100) may refer to the length from the second side end (110E2) of the substrate (100) to the point where the bending of the substrate (100) begins. For example, the second length (L2) of the substrate (100) may refer to the length from the second side end (110E2) of the substrate (100) to the first protection pattern (810).

[0154] At this time, the second length (L2) described above may be 15 mm or less. For example, the second length (L2) described above may be 12 mm or less. Preferably, the second length (L2) described above may be 10 mm or less.

[0155] If the second length (L2) described above exceeds 15 mm, the first length (L1) of the substrate (100) may be increased accordingly. And, when the first length (L1) of the substrate (100) is increased, the bezel area of ​​the electronic device may be increased when the flexible circuit board (1000) is coupled to a display panel and / or an external circuit board, and the size of the electronic device may be increased as a result.

[0156] Also, if the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, the thickness (T) of the substrate (100) may be 25 μm or less. Preferably, if the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, the thickness of the substrate (100) may be 23 μm or less. More preferably, if the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, the thickness (T) of the substrate (100) may be 20 μm or less.

[0157] If the thickness (T) of the substrate (100) exceeds 25 μm, stress may be applied to the electrical connection area or the physical connection area while the flexible circuit board (1000) is bonded to the display panel, and as a result, cracks may occur in the electrical connection area or the physical connection area. In addition, if the above-mentioned cracks occur, physical reliability and / or electrical reliability may be reduced. Specifically, the flexible circuit board is bonded to the display panel and the external circuit board while in a bent state, and a springback phenomenon may occur in which it attempts to return to its original state from the above-mentioned bonding state. Furthermore, due to the above-mentioned springback phenomenon, stress may be applied to the electrical connection area or the physical connection area, thereby reducing physical reliability and / or electrical reliability.

[0158] Furthermore, the first length (L1) and second length (L2) of the substrate (100) are reduced, and as described above, the first length (L1) of the substrate (100) may be 35 mm or less, and the second length (L2) of the substrate (100) may be 15 mm or less. Also, if the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, the springback size occurring under the same conditions may increase further. Accordingly, the embodiment reduces the thickness (T) of the substrate (100) to 25 μm or less as the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, and thereby reduces the springback size. Through this, the embodiment can prevent the springback phenomenon and further minimize the springback size. Accordingly, the embodiment can enable the flexible circuit board to be stably connected to a display panel or an external circuit board, thereby improving physical reliability and / or electrical reliability. Accordingly, the embodiment can enable the flexible circuit board to operate more stably, thereby further improving product reliability.

[0159] Additionally, the thickness (T) of the substrate (100) may be 10 μm or more. Preferably, the thickness (T) of the substrate (100) may be 12 μm or more. More preferably, the thickness (T) of the substrate (100) may be 15 μm or more. If the thickness (T) of the substrate (100) is less than 10 μm, processability in the manufacturing process of the flexible circuit board may be reduced. For example, the flexible circuit board is manufactured through a roll-to-roll process. At this time, in order to secure the flatness of the substrate (100) in the manufacturing process of the flexible circuit board, a tension of a certain level or more is applied to the substrate (100). Here, if the thickness (T) of the substrate (100) is less than 10 μm, the magnitude of the applied tension may be reduced, and as a result, the flatness of the substrate (100) may be reduced. In addition, if the thickness (T) of the substrate (100) is less than 10㎛, the problem of the substrate (100) being torn by the applied tension may occur.

[0160]

[0161] A flexible circuit board according to the second embodiment will be described below.

[0162] At this time, the flexible circuit board of the first embodiment may be a single-sided flexible circuit board in which an upper wiring pattern is arranged only on the first surface (1S) of the substrate (100).

[0163] In contrast, the flexible circuit board of the second embodiment may be a double-sided flexible circuit board in which an upper wiring pattern is disposed on the first surface (1S) of the substrate (100) and a lower wiring pattern is disposed on the second surface (2S) of the substrate (100).

[0164] Hereinafter, a flexible circuit board of the second embodiment will be described with reference to the attached drawings, provided that components substantially identical to the flexible circuit board of the first embodiment are given the same reference numerals and detailed descriptions thereof are omitted.

[0165] FIG. 3 is a cross-sectional view of a flexible circuit board according to a second embodiment cut along A-A' of FIG. 1b. In particular, FIG. 3 is a cross-sectional view cut along A-A' of FIG. 1b in an effective area (AA) of a flexible circuit board (1000).

[0166] The flexible circuit board (1000) includes a first region (R1) and a second region (R2). That is, the flexible circuit board (1000) includes an effective region (AA), and the effective region (AA) can be divided into a first region (R1) and a second region (R2). The first region (R1) can be defined as a bending region of the flexible circuit board (1000), and the second region (R2) can be defined as a region excluding the first region (R1).

[0167] A flexible circuit board (1000) includes a substrate (100). An upper wiring pattern (200U) is disposed on a first surface (1S) of the substrate (100). Additionally, a lower wiring pattern (200L) is disposed on a second surface (2S) of the substrate (100).

[0168] The upper wiring pattern (200U) may be provided in multiple layers. For example, the upper wiring pattern (200U) may include an upper wiring layer (200a) and an upper plating layer (200b) disposed on the upper wiring layer (200a).

[0169] An upper plating layer (200b) may be disposed on the upper wiring layer (200a). The upper plating layer (200b) may include a first upper plating layer (200b1) and a second upper plating layer (200b2).

[0170] The first upper plating layer (200b1) may be partially disposed on the upper wiring layer (200a). The first upper plating layer (200b1) may be disposed on the second region (R2) excluding the first region (R1) on the upper wiring layer (200a). The first upper plating layer (200b1) may be disposed in an area other than the region where the first protective pattern (311) of the upper protective layer (310) on the upper wiring layer (200a) is disposed. For example, the first upper plating layer (200b1) may be disposed in the area where the second protective pattern (312) on the upper wiring layer (200a) is disposed.

[0171] That is, the first upper plating layer (200b1) may not be placed on the first region (R1) on the upper wiring layer (200a). Accordingly, the first upper plating layer (200b1) may include an open portion (200b1O) provided in the first region (R1). For example, the width of the open portion (200b1O) may correspond to the width of the first region (R1). Specifically, the side of the first upper plating layer (200b1) may be placed in the boundary region between the first region (R1) and the second region (R1).

[0172] The first upper plating layer (200b1) may be spaced apart from each other by an open portion (200b1O). For example, the first upper plating layer (200b1) at the outer side of one end of the first region (R1) and the first upper plating layer (200b1) at the outer side of the other end of the first region (R1) may not be connected to each other.

[0173] The second upper plating layer (200b2) may be disposed on the first upper plating layer (200b1). The second upper plating layer (200b2) may be partially disposed on the first upper plating layer (200b1).

[0174] The second upper plating layer (200b2) may be disposed in an area other than the area where the second protection pattern (312) of the upper protection layer (310) is disposed. For example, the upper protection layer (310) may include a plurality of open areas. The upper protection layer (310) may include a first open area (OR1) and a second open area (OR2). The first open area (OR1) of the upper protection layer (310) may correspond to a chip mounting area (CHA1). The second open area (OR2) of the upper protection layer (310) may be a first connection area connected to an external circuit board. That is, the substrate (100) may include a first side end and a second side end opposite to the first side end. And, the first open area (OR1) may be located between the first side end and the second side end. Additionally, the second open area (OR2) may be spaced apart from the first open area (OR1) and located closer to the first side than the first open area (OR1).

[0175] The second upper plating layer (200b2) may be provided on the first upper plating layer (200b1) in an area excluding the second open area (OR2). That is, the upper plating layer (200b) may not be placed in the first area (R1) of the flexible circuit board (1000) of the embodiment. Specifically, the first upper plating layer (200b1) and the second upper plating layer (200b2) may not be placed in the first area (R1) of the flexible circuit board (1000). By doing so, the embodiment can prevent cracks occurring during bending of the flexible circuit board (1000) in the first area (R1), and thereby further improve the physical reliability and / or electrical reliability of the flexible circuit board (1000). In addition, the embodiment can prevent the upper wiring pattern (200U) from being damaged by the tensile force of the upper wiring pattern (200U) that occurs when the flexible circuit board (1000) is bent in the first region (R1), thereby improving the durability of the upper wiring pattern (200U).

[0176] In this way, the upper plating layer (200b) may be provided in two layers. That is, the upper plating layer (200b) may include a first upper plating layer (200b1) and a second upper plating layer (200b2).

[0177] The upper protective layer (310) may have a two-layer structure including a first protective pattern (311) and a second protective pattern (312).

[0178] The first protection pattern (311) of the upper protection layer (310) may be provided in the first region (R1) of the flexible circuit board. That is, the first protection pattern (311) of the upper protection layer (310) may be in direct contact with the upper wiring layer (200a) of the upper wiring pattern (200U). For example, the lower surface of the first protection pattern (311) of the upper protection layer (310) may be in direct contact with the upper surface of the upper wiring layer (200a) and may not be in contact with the upper plating layer (200b).

[0179] The second protection pattern (312) of the upper protection layer (310) may be placed on the first protection pattern (311) and the first upper plating layer (200b1). That is, the second protection pattern (312) of the upper protection layer (310) may be placed in an area excluding the first open area (OR1) and the second open area (OR2).

[0180] Accordingly, on the first surface (1S) of the substrate (100), there may be a first placement area in which an upper wiring layer (200a), a first protection pattern (311), and a second protection pattern (312) are placed, a second placement area in which an upper wiring layer (200a), a first upper plating layer (200b1), and a second protection pattern (312) are placed, and an area in which an upper wiring layer (200a), a first upper plating layer (200b1), and a second upper plating layer (200b1) are placed.

[0181] The upper protective layer (310) may include a first protective pattern (311) and a second protective pattern (312). The first protective pattern (311) may be placed in a first region (R1), which is a bending region of the upper wiring layer (200a), and the second protective pattern (312) may be placed on the first protective pattern (311).

[0182] The first protection pattern (311) can be in contact with the upper wiring layer (200a) and the first upper plating layer (200b1). The first protection pattern (311) can be in contact with the upper surface of the upper wiring layer (200a) and the side surface of the first upper plating layer (200b1) on the first region (R1).

[0183] That is, the first protection pattern (311) is in direct contact with the upper wiring layer (200a), thereby dispersing the stress that may occur during bending of the first region (R1), and thus further improving the physical reliability and / or electrical reliability of the flexible circuit board. Additionally, the lower surface of the second protection pattern (312) is in contact with the first upper plating layer (200b1) and is not in contact with the second upper plating layer (200b1). Accordingly, it is possible to prevent the thickness of the flexible circuit board from increasing by the thickness of the second upper plating layer (200b2).

[0184] Meanwhile, a lower wiring pattern (200L) and a lower protection layer (320) may be disposed on the second surface (2S) of the substrate (100).

[0185] A lower wiring pattern (200L) is disposed on the second surface (2S) of the substrate (100). Additionally, a lower protective layer (320) is disposed under the lower wiring pattern (200L) of the substrate (100).

[0186] The lower wiring pattern (200L) may be provided in multiple layers. For example, the lower wiring pattern (200L) may include a lower wiring layer (200c) and a lower plating layer (200d) disposed under the lower wiring layer (200c).

[0187] The lower wiring layer (200c) may be disposed with a thickness of 1 µm to 20 µm. For example, the lower wiring layer (200c) may be disposed with a thickness of 5 µm to 20 µm. For example, the lower wiring layer (200c) may be disposed with a thickness of 5 µm to 15 µm.

[0188] If the thickness of the lower wiring layer (200c) is less than 1㎛, the resistance of the lower wiring layer (200c) may increase. If the thickness of the lower wiring layer (200c) is greater than 20㎛, it may be difficult to implement a fine pattern.

[0189] A lower plating layer (200d) may be disposed on the lower wiring layer (200c). The lower plating layer (200d) may include a first lower plating layer (200d1) and a second lower plating layer (200d2).

[0190] The first lower plating layer (200d1) may be placed entirely under the lower wiring layer (200c). The first lower plating layer (200d1) may overlap with the lower protective layer (320) along the thickness direction. Additionally, the lower protective layer (320) may include a third open area (OR3). The third open area (OR3) may be a second connection area for connecting the lower wiring pattern (200L) and the display panel. The third open area (OR3) may be located closer to the second side end of the substrate (100) than the first open area (OR1). That is, the first lower plating layer (200d1) may be placed in each of the overlap area overlapping with the lower protective layer (320) along the thickness direction and the third open area (OR3) of the lower protective layer (320).

[0191] The second lower plating layer (200d2) may be placed entirely under the first lower plating layer (200d1). The second lower plating layer (200d2) may be placed in an area where the thickness direction overlaps with the lower protective layer (320), and in a third open area (OR3) of the lower protective layer (320).

[0192] The lower plating layer (200d) may be provided in two layers. That is, the lower plating layer (200d) may include a first lower plating layer (200d1) and a second lower plating layer (200d2).

[0193] Additionally, the substrate (100) of the embodiment is provided with a via electrode connecting an upper wiring pattern (200U) and a lower wiring pattern (200L). The via electrode includes a first open region (OR1) and a first via electrode (V1) that overlaps along the thickness direction. Additionally, the via electrode includes a second via electrode (V2) adjacent to one end of the substrate (100) from the first open region (OR1). Furthermore, the embodiment is configured such that a first region (R1) is provided between the first via electrode (V1) and the second via electrode (V2). Preferably, the first region (R1) may be extended between the first via electrode (V1) and the second via electrode (V2) in a direction perpendicular to the separation direction of the first via electrode (V1) and the second via electrode (V2). Through this, the embodiment can improve the rigidity of the flexible circuit board by the first via electrode (V1) and the second via electrode (V2) when bending the flexible circuit board in the first region (R1), and thereby further improve the physical reliability and / or electrical reliability of the flexible circuit board.

[0194] Additionally, the lower wiring pattern (200L) may not be placed in one area of ​​the second surface (2S) of the substrate (100). Preferably, the lower wiring pattern (200L) may not overlap in the thickness direction with the area between the first open area (OR1) and the second open area (OR2) of the upper protective layer (310). Preferably, the lower wiring pattern (200L) may not be placed in the area of ​​the second surface (2S) of the substrate (100) that overlaps in the thickness direction with the area between the first open area (OR1) and the second open area (OR2) of the upper protective layer (310), and may be provided in an area that does not overlap in the thickness direction with the area between the first open area (OR1) and the second open area (OR2) of the upper protective layer (310). Through this, the embodiment can control the placement area of ​​the lower wiring pattern (200L) to control the tensile force of the lower wiring pattern (200L) that occurs during bending of the flexible circuit board, and thereby further improve the durability of the lower wiring pattern (200L). However, a lower dummy pattern may be provided under the second surface (2S) of the substrate (100) that overlaps in the thickness direction with the area between the first open area (OR1) and the second open area (OR2) of the upper protective layer (310).

[0195] Meanwhile, the upper protective layer (310) may include a first protective pattern (311) and a second protective pattern (312). The first protective pattern (311) may be placed in a first region (R1), which is a bending region of the upper wiring layer (200a), and the second protective pattern (312) may be placed on the first protective pattern (311).

[0196] At this time, the second length (L2) from the second side end (110E2) of the substrate (100) to the first protection pattern (311) of the upper protection layer (310) may have a second length (L2). The second length (L2) described above may be smaller than the first length (L1) of the substrate (100). That is, the second length (L2) of the substrate (100) may refer to the length of the flexible circuit board (1000) in a bending state. For example, the second length (L2) of the substrate (100) may refer to the length from the second side end (110E2) of the substrate (100) to the point where the bending of the substrate (100) begins. For example, the second length (L2) of the substrate (100) may refer to the length from the second side end (110E2) of the substrate (100) to the first protection pattern (311).

[0197] At this time, the second length (L2) described above may be 15 mm or less. For example, the second length (L2) described above may be 12 mm or less. Preferably, the second length (L2) described above may be 10 mm or less.

[0198] If the second length (L2) described above exceeds 15 mm, the first length (L1) of the substrate (100) may be increased accordingly. And, when the first length (L1) of the substrate (100) is increased, the bezel area of ​​the electronic device may be increased when the flexible circuit board (1000) is coupled to a display panel and / or an external circuit board, and the size of the electronic device may be increased as a result.

[0199] Also, if the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, the thickness (T) of the substrate (100) may be 25 μm or less. Preferably, if the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, the thickness of the substrate (100) may be 23 μm or less. More preferably, if the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, the thickness (T) of the substrate (100) may be 20 μm or less.

[0200] If the thickness (T) of the substrate (100) exceeds 25 μm, stress may be applied to the electrical connection area or the physical connection area while the flexible circuit board (1000) is bonded to the display panel, and as a result, cracks may occur in the electrical connection area or the physical connection area. In addition, if the above-mentioned cracks occur, physical reliability and / or electrical reliability may be reduced. Specifically, the flexible circuit board is bonded to the display panel and the external circuit board while in a bent state, and a springback phenomenon may occur in which it attempts to return to its original state from the above-mentioned bonding state. Furthermore, due to the above-mentioned springback phenomenon, stress may be applied to the electrical connection area or the physical connection area, thereby reducing physical reliability and / or electrical reliability.

[0201] At this time, the first length (L1) and the second length (L2) of the substrate (100) in the second embodiment are reduced, and as described above, the first length (L1) of the substrate (100) may be 35 mm or less, and the second length (L2) of the substrate (100) may be 15 mm or less. Also, if the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less, the springback size occurring under the same conditions may be further increased. Accordingly, the embodiment reduces the thickness (T) of the substrate (100) to 25 μm or less and reduces the springback size accordingly, as the first length (L1) of the substrate (100) is 35 mm or less, or the second length (L2) of the substrate (100) is 15 mm or less. Through this, the embodiment can prevent springback phenomena and further minimize the size of the springback. Accordingly, the embodiment can ensure that the flexible circuit board is stably connected to a display panel or an external circuit board, thereby improving physical reliability and / or electrical reliability. Accordingly, the embodiment can enable the flexible circuit board to operate more stably, thereby further improving product reliability.

[0202] Additionally, the thickness (T) of the substrate (100) may be 10 μm or more. Preferably, the thickness (T) of the substrate (100) may be 12 μm or more. More preferably, the thickness (T) of the substrate (100) may be 15 μm or more. If the thickness (T) of the substrate (100) is less than 10 μm, processability in the manufacturing process of the flexible circuit board may be reduced. For example, the flexible circuit board is manufactured through a roll-to-roll process. At this time, in order to secure the flatness of the substrate (100) in the manufacturing process of the flexible circuit board, a tension of a certain level or more is applied to the substrate (100). Here, if the thickness (T) of the substrate (100) is less than 10 μm, the magnitude of the applied tension may be reduced, and as a result, the flatness of the substrate (100) may be reduced. In addition, if the thickness (T) of the substrate (100) is less than 10㎛, the problem of the substrate (100) being torn by the applied tension may occur.

[0203]

[0204] FIG. 4 is a cross-sectional view of a flexible circuit board according to a third embodiment cut along A-A' of FIG. 1b.

[0205] Referring to FIG. 4, the flexible circuit board according to the second embodiment can be connected to an external circuit board and a display panel, respectively, on the first surface (1S) of the substrate (100).

[0206] Accordingly, the upper protective layer (310) may include a first open area (OR1), a second open area (OR2), and a third open area (OR3).

[0207] And, the lower protective layer (320) may not have an open area.

[0208] Accordingly, the lower wiring pattern (200L) may include a lower wiring layer (200c) and a lower plating layer (200d). At this time, the lower plating layer (200d) of the lower wiring pattern (200L) may have a layer structure different from that of the previous embodiment. For example, the lower plating layer (200d) may be provided as a single layer. Preferably, the lower plating layer (200d) according to the embodiment of FIG. 4 may have a structure that includes only the first lower plating layer (200d1). That is, the lower protective layer (320) does not have an open area, and accordingly, the lower wiring pattern (200L) may be entirely covered by the lower protective layer (320). Thus, the embodiment may allow the lower plating layer (200d) to be provided as a single layer, thereby simplifying the manufacturing process, reducing manufacturing costs, and improving product yield. At this time, the lower plating layer (200d) provided as a single layer can prevent oxidation of the lower wiring layer (200c) during the process of forming the lower protective layer (320), and furthermore, can improve adhesion with the lower protective layer (320).

[0209] Additionally, the lower wiring pattern (200L) may not be placed in one area of ​​the second surface (2S) of the substrate (100). Preferably, the lower wiring pattern (200L) may not overlap in the thickness direction with the area between the first open area (OR1) and the second open area (OR2) of the upper protective layer (310). Preferably, the lower wiring pattern (200L) may not be placed in the area of ​​the second surface (2S) of the substrate (100) that overlaps in the thickness direction with the area between the first open area (OR1) and the second open area (OR2) of the upper protective layer (310), and may be provided in an area that does not overlap in the thickness direction with the area between the first open area (OR1) and the second open area (OR2) of the upper protective layer (310). Through this, the embodiment can control the placement area of ​​the lower wiring pattern (200L) to control the tensile force of the lower wiring pattern (200L) that occurs during bending of the flexible circuit board, and thereby further improve the durability of the lower wiring pattern (200L). However, a lower dummy pattern may be provided under the second surface (2S) of the substrate (100) that overlaps in the thickness direction with the area between the first open area (OR1) and the second open area (OR2) of the upper protective layer (310).

[0210] Hereinafter, the springback phenomenon according to the first length (L1), second length (L2) of the above-described substrate (100) and the thickness (T) of the substrate (100) is explained in more detail. Preferably, the springback phenomenon according to the first length (L1), second length (L2) of the substrate (100) and the thickness (T) of the substrate (100) in the effective area is explained in more detail below.

[0211]

[0212] FIG. 5 is a plan view showing an electronic device in which a COF module, a circuit board, and a display panel are combined in an embodiment; FIG. 6 is a diagram showing the connection relationship of a COF module, a circuit board, and a display panel according to a first embodiment; FIG. 7 is a diagram showing the connection relationship of a COF module, a circuit board, and a display panel according to a second embodiment; FIG. 8 is a diagram showing a comparison of connection relationships according to a comparative example and an embodiment; and FIG. 9 is a diagram for explaining the springback size according to the length of the substrate.

[0213] A chip (C) can be mounted on the chip mounting area (CHA) of the flexible circuit board (1000) described in FIGS. 1a to 4 to form a COF module (2000).

[0214] Referring to FIG. 5, one end of the COF module (2000) is connected to a display panel (4000), and the other end is connected to a circuit board (3000).

[0215] At this time, the resolution of the display panel (4000) increases, or the functions required of the display panel (4000) increase. Accordingly, it may be difficult to electrically connect the display panel (4000) and the circuit board (3000) with only one COF module (2000).

[0216] Accordingly, a plurality of COF modules (2000) may be provided between the display panel (4000) and the circuit board (3000). For example, six COF modules (2000) may be provided between the display panel (4000) and the circuit board (3000), but are not limited thereto. For example, the number of COF modules (2000) may increase or decrease depending on the number of signal transmission lines between the display panel (4000) and the circuit board (3000).

[0217] At this time, referring to FIG. 6, the display panel (4000) and the circuit board (3000) are placed on one side of the COF module (2000). That is, in the flexible circuit board (1000) according to the embodiment, the display panel (4000) and the circuit board (3000) are placed on the same side of the COF module (2000).

[0218] Referring to FIG. 7, the display panel (4000) and the circuit board (3000) are placed on the other side of the COF module (2000). That is, in the flexible circuit board according to the second embodiment, the display panel (4000) and the circuit board (3000) are placed on the other side of the COF module (2000).

[0219] Since the COF module (2000) includes a flexible substrate, it has a rigid shape and a bending shape between the display panel (3000) and the circuit board (4000). That is, the COF module (2000) may include a bending region (BA).

[0220] The COF module (2000) connects a display panel (4000) and a circuit board (3000) that are positioned facing each other in a curved shape. Accordingly, the thickness of the electronic device is reduced. In addition, the design freedom of the electronic device is improved. Furthermore, the wiring of the COF module (2000) is not broken even in a curved shape. Accordingly, the reliability of the electronic device is improved. Since the COF module is flexible, it can be used in various electronic devices.

[0221] As described above, when the COF module (2000), circuit board (3000), and display panel (4000) are combined, the second length (L2) of the COF module (2000) constitutes the bezel area of ​​the electronic device, and the size of the electronic device increases accordingly. Accordingly, development is underway to reduce the aforementioned bezel area.

[0222] Accordingly, as described above, the length of the flexible circuit board (1000) and the length of the COF module (2000) corresponding to the first length (L1) of the substrate (100) may be 35 mm or less. At this time, if the length of the flexible circuit board (1000) and the length of the COF module (2000) decrease, a springback phenomenon may occur in which the COF module (2000) attempts to return to its original state while the COF module (2000) is combined in a bent state.

[0223] The springback size can be increased according to the length of the flexible circuit board (1000) and the COF module (2000).

[0224] That is, referring to (A) of FIG. 8, in the comparative example, the length of the flexible circuit board (1000') and the COF module (2000') before bending exceeds 40 mm, and accordingly, the second length (L2') in the bent state also exceeds 20 mm.

[0225] At this time, when the length of the flexible circuit board (1000') and the COF module (2000') before bending exceeds 40mm and the second length (L2') in the bent state also exceeds 20mm, even if the thickness (T) of the substrate (100) exceeds 30㎛, the springback size was at the level of 150mN. Accordingly, in the comparative example, since the springback size was at the level of 150mN regardless of the thickness (T) of the substrate (100), no effort was required to reduce it. Furthermore, in the comparative example, it was not recognized that the springback size increased according to the second length (L2') of the flexible circuit board (1000') and the COF module (2000'), and furthermore, the relationship between the second length (L2') of the flexible circuit board (1000') and the springback size was not recognized.

[0226] In contrast, referring to (B) of FIG. 12, in the embodiment, the first length (L1) of the flexible circuit board (1000) and the COF module (2000) is 35 mm or less, and the second length (L2) is 15 mm or less. In addition, in the embodiment, it was confirmed that when the first length (L1) of the flexible circuit board (1000) and the COF module (2000) is 35 mm or less and the second length (L2) is reduced to 15 mm or less, the springback size increases accordingly.

[0227] That is, referring to FIG. 9, when the first length (L1) of the flexible circuit board (1000) and the COF module (2000) is 35 mm or less and the second length (L2) is 15 mm or less, and the thickness (T) of the substrate (100) is applied as 35 μm, it was confirmed that the springback size after bending of the flexible circuit board (1000) and the COF module (2000) is 344 mN.

[0228] In addition, when the first length (L1) of the flexible circuit board (1000) and the COF module (2000) is 35 mm or less and the second length (L2) is 15 mm or less, and the thickness (T) of the substrate (100) is 30 μm, it was confirmed that the springback size after bending of the flexible circuit board (1000) and the COF module (2000) is 212 mN.

[0229] In addition, when the first length (L1) of the flexible circuit board (1000) and the COF module (2000) is 35 mm or less and the second length (L2) is 15 mm or less, and the thickness (T) of the substrate (100) is 25 μm, it was confirmed that the springback size after bending of the flexible circuit board (1000) and the COF module (2000) is reduced to 127 mN.

[0230] Furthermore, when the first length (L1) of the flexible circuit board (1000) and the COF module (2000) is 35 mm or less and the second length (L2) is 15 mm or less, and the thickness (T) of the substrate (100) is 20 μm, it was confirmed that the springback size after bending of the flexible circuit board (1000) and the COF module (2000) is reduced to a level of 100 mN.

[0231] Additionally, a plurality of COF modules (2000) are arranged between the display panel (4000) and the circuit board (3000). Accordingly, a larger springback size may occur in the electronic device as the springback size acting on the plurality of COF modules (2000) accumulates. Consequently, a large stress is applied to the electrical contact area or mechanical contact area between the COF module (2000), the display panel (4000), and the circuit board (3000), and a problem may arise in which electrical reliability and / or mechanical reliability is degraded as a result.

[0232] Accordingly, in the embodiment, the first length (L1) of the flexible circuit board (1000) and the COF module (2000) is 35 mm or less and the second length (L2) is 15 mm or less, thereby reducing the thickness (T) of the substrate (100) to 25 μm, and consequently, the springback size after bending of the flexible circuit board (1000) and the COF module (2000) is reduced to a level of 127 mN. Therefore, the embodiment can significantly reduce the stress acting on the electrical contact area or mechanical contact area due to the springback phenomenon even when a plurality of COF modules (2000) are arranged between a plurality of display panels (4000) and a circuit board (3000). Accordingly, the embodiment can improve electrical reliability and / or mechanical reliability.

[0233]

[0234] FIGS. 10 to 12 are drawings relating to an electronic device including a flexible circuit board according to an embodiment.

[0235] For example, referring to FIG. 10, the COF module can be applied to a bendable flexible touch window. Thus, a touch device device including it may be a flexible touch device device. Thus, a user can bend or fold it with their hand. Such a flexible touch window can be applied to wearable touch devices, etc.

[0236] Referring to FIG. 11, the COF module can be applied to various wearable touch devices including curved displays. Accordingly, an electronic device including the COF module can be made slimmer or lighter.

[0237] Referring to FIG. 12, the COF module can be used in various electronic devices having a display part, such as TVs, monitors, and laptops. At this time, the COF module can also be used in electronic devices having a curved display part.

[0238]

[0239] The features, structures, effects, etc. described in the above-described embodiments are included in at least one embodiment of the present invention and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment may be combined or modified and implemented in other embodiments by a person skilled in the art to which the embodiments belong. Therefore, details regarding such combinations and modifications should be interpreted as being included within the scope of the present invention.

[0240] Furthermore, although the above description has focused on the embodiments, this is merely illustrative and does not limit the invention. Those skilled in the art will understand that various modifications and applications not exemplified above are possible within the scope of the essential characteristics of the embodiments. For example, each component specifically shown in the embodiments may be modified and implemented. Differences related to such modifications and applications should be interpreted as being included within the scope of the invention as defined in the appended claims.

Claims

A substrate including an effective area that is cut along a cutting line, and including a first side end of the effective area and a second side end of the effective area opposite to the first side end; A conductive pattern portion comprising a pad disposed on the effective area of ​​the above description and disposed adjacent to the first side end and the second side end; and It includes a protective layer disposed on the conductive pattern portion, and The first length of the above-described material between the first side end and the second side end is 35 mm or less, and A flexible circuit board having a thickness of 25㎛ or less as described above. In paragraph 1, The first length is 15mm to 35mm, and A flexible circuit board having a thickness of 10㎛ to 25㎛. In paragraph 1, The above first length is 30 mm or less, and A flexible circuit board having a thickness of 20㎛ or less as described above. In paragraph 1, The above description has a bending region, and A flexible circuit board in which the second length from the second side end to the bending region of the above description is 15 mm or less. In paragraph 4, The second length from the second side end of the above description to the bending region is 10 mm or less, and A flexible circuit board having a thickness of 20㎛ or less as described above. In paragraph 1, The above conductive pattern portion is, The upper wiring layer disposed on the above-mentioned substrate; a first upper plating layer disposed on the upper wiring layer; and a second upper plating layer disposed on the first upper plating layer within an area corresponding to the pad, The first upper plating layer includes an open portion, and A flexible circuit board comprising a protective layer including a first protective pattern disposed within the opening of the first upper plating layer, and a second protective pattern disposed on the first upper plating layer and the first protective pattern. In paragraph 6, A flexible circuit board in which the second length from the second side end to the first protection pattern is 15 mm or less. In Paragraph 7, The second length from the second side end to the first protection pattern is 10 mm or less, and A flexible circuit board having a thickness of 20㎛ or less as described above. In paragraph 1, The above conductive pattern portion is, It includes an upper wiring pattern disposed on one side of the above-mentioned substrate; and a lower wiring pattern disposed under the other side of the above-mentioned substrate, The above protective layer is, A flexible circuit board comprising: an upper protective layer disposed on the upper wiring pattern; and a lower protective layer disposed under the lower wiring pattern. In paragraph 9 A flexible circuit board comprising at least one of the upper wiring pattern and the lower wiring pattern, the pad disposed on one side or the other side of the effective area adjacent to the first side end and the second side end.

Images