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

Abstract

A flexible circuit board according to an embodiment includes: a substrate including a first surface and a second surface opposite to the first surface; a circuit pattern on the first surface; and a protective layer on the circuit pattern, wherein the circuit pattern includes a first circuit pattern connected to a chip and a circuit board and a second circuit pattern connected to the chip and a display panel; the first circuit pattern includes a first pad part connected to the chip, a second pad part connected to the circuit board, and a first wire part connecting the first pad part and the second pad part; the second circuit pattern includes a third pad part connected to the chip, a fourth pad part connected to the display panel, and a second wire part connecting the third pad part and the fourth pad part; and a first direction in which the second pad part and the fourth pad part face each other, a second direction perpendicular to the first direction, and a third direction between the first direction and the second direction are defined, and at least one fourth pad part extends in the third direction.

Description

Flexible circuit boards, COF modules and electronic devices including the same

[0001] The present invention 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. Consequently, there is a growing demand for high-density semiconductor chips to be mounted in narrow spaces within electronic devices.

[0003] COF (Chip-On-Film) comprises a substrate and a chip on the substrate. The substrate is flexible, meaning COF is a flexible circuit board. Therefore, COF is used in flexible displays. For example, COF can be applied to various wearable electronic devices. Furthermore, COF has a fine pitch, making it suitable for high-resolution displays.

[0004] A chip includes a semiconductor chip. 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 display panel through a circuit pattern. For example, pads are arranged at one end and the other end of the circuit pattern. One pad is electrically connected to a terminal on the chip, and the other pad is connected to a terminal on the circuit board and display panel. Accordingly, the chip, circuit board, and display panel are electrically connected through the COF. This allows signals to be transmitted to the display panel through the circuit pattern.

[0006] Flexible circuit boards bend in one direction. Consequently, they contain a bending region. Consequently, stress occurs in the bending region. Consequently, the circuit pattern in the bending region may delaminate.

[0007] Display panels come in various sizes. Specifically, display panels come in various sizes depending on their intended use. Accordingly, the terminals on the display panel can have various sizes depending on the intended use.

[0008] Therefore, the pad portion of the flexible circuit board is formed depending on the type of display panel. Consequently, the flexible circuit board is only combined with display panels for specific applications. Consequently, the manufacturing process becomes more difficult.

[0009] Therefore, a new structure of flexible circuit board, COF module and electronic device including the same that can solve the above problems are required.

[0010] As a patent related to a flexible circuit board, Korean registered patent KR10-0618898 (2006.09.01) is disclosed.

[0011] The embodiment provides a flexible circuit board having improved reliability.

[0012] The embodiment provides a flexible circuit board connected to various display panels.

[0013] The embodiment provides a flexible circuit board and a COF module capable of measuring the performance of a display panel before connecting the display panel and the flexible circuit board.

[0014] The technical tasks to be achieved in the proposed embodiment are not limited to the technical tasks mentioned above, and other technical tasks not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the proposed embodiment belongs from the description below.

[0015] According to one embodiment, a flexible circuit board comprises: a substrate including a first surface and a second surface opposite to the first surface; a circuit pattern disposed on the first surface; and a protective layer disposed on the circuit pattern and including a plurality of open areas, wherein the substrate includes first and second side ends facing each other in a first direction, the open areas including a first open area provided between the first side end and the second side end, a second open area spaced apart from the first open area and closer to the first side end, and a third open area spaced apart from the first open area and closer to the second side end, wherein the circuit pattern comprises: a first circuit pattern including a first pad portion disposed in the first open area; a second pad portion disposed in the second open area; and a first wiring portion connecting the first pad portion and the second pad portion; a third pad portion disposed in the first open area; a fourth pad portion disposed in the third open area; And a second circuit pattern including a second wiring portion connecting between the third pad portion and the fourth pad portion, wherein the first direction in which the second pad portion and the fourth pad portion face each other, a second direction perpendicular to the first direction, and a third direction between the first direction and the second direction are defined, and at least one fourth pad portion extends in the third direction on the substrate.

[0016] Additionally, the fourth pad portion extends in the first direction and the third direction.

[0017] Additionally, the fourth pad portion includes a central pad portion and an outer pad portion, the central pad portion extending in the first direction, and the outer pad portion extending in the third direction.

[0018] Additionally, the inclination angle of the outer pad portion increases as it moves away from the central pad portion.

[0019] In addition, the second wiring portion includes a 2-1 wiring portion and a 2-2 wiring portion, the 2-1 wiring portion extends in the first direction, the 2-2 wiring portion extends in the first direction and the third direction, and the maximum inclination angle of the outer pad portion is smaller than the maximum inclination angle of the 2-2 wiring portion.

[0020] Additionally, the outer pad portion extends in a different direction from at least one pad portion among the first pad portion, the second pad portion, and the third pad portion.

[0021] Additionally, the circuit pattern further includes a third circuit pattern including a fifth pad portion arranged in the second open area; a sixth pad portion arranged in the third open area; and a third wiring portion connecting between the fifth pad portion and the sixth pad portion.

[0022] Additionally, at least one sixth pad portion extends in the third direction.

[0023] Additionally, the sixth pad portion extends in the first direction and the third direction.

[0024] Additionally, the sixth pad portion includes a central pad portion and an outer pad portion, the central pad portion extending in the first direction, and the outer pad portion extending in the third direction.

[0025] Additionally, the inclination angle of the outer pad portion increases as it moves away from the central pad portion.

[0026] Additionally, the outer pad portion extends in a different direction from at least one pad portion among the first pad portion, the second pad portion, the third pad portion, and the fifth pad portion.

[0027] Meanwhile, the flexible circuit board of the embodiment further includes a test pattern arranged on the substrate.

[0028] Additionally, the test pattern includes a seventh pad portion, an eighth pad portion, and a fourth wiring portion, and the line width of the seventh pad portion is larger than the line width of the eighth pad portion.

[0029] Additionally, the seventh pad portion is adjacent to the second wiring portion, the eighth pad portion is adjacent to the fourth pad portion, and the fourth wiring portion connects the seventh pad portion and the eighth pad portion.

[0030] Additionally, the seventh pad portion is connected to the test device, and the eighth pad portion is placed in the third open area.

[0031] Additionally, the protective layer is not placed on the seventh pad portion and the eighth pad portion.

[0032] In addition, the protective layer is disposed on the seventh pad portion, the protective layer is not disposed on the eighth pad portion, the seventh pad portion includes a first region where the protective layer is not disposed and a second region where the protective layer is disposed, and the area of ​​the first region is 80% to 99% of the area of ​​the seventh pad portion.

[0033] Additionally, the line width of the seventh pad portion is larger than the line width of at least one of the first pad portion, the second pad portion, the third pad portion, and the fourth pad portion.

[0034] In addition, the seventh pad portion includes a 7-1 pad portion and a 7-2 pad portion on the first surface, the fourth wiring portion includes a 4-1 wiring portion on the first surface and a 4-2 wiring portion on the second surface, the eighth pad portion includes an 8-1 pad portion and an 8-2 pad portion on the second surface, the 8-1 pad portion is adjacent to the 4th pad portion, the 8-2 pad portion is adjacent to the 6th pad portion, and the 4-1 wiring portion and the 4-2 wiring portion are connected through a via.

[0035] Additionally, the line width of the seventh pad portion is larger than the line width of the via.

[0036] A flexible circuit board according to an embodiment includes a second circuit pattern connected to a display panel and a chip. The second circuit pattern includes a second wiring portion, a third pad portion, and a fourth pad portion.

[0037] The second wiring section includes a second wiring section 2-1 and a second wiring section 2-2. The second wiring section 2-1 extends in a linear direction, and the second wiring section 2-2 extends in a diagonal direction. The second wiring section 2-1 has a length within a set range. Therefore, the second wiring section 2-1 is arranged mostly or entirely on the bending area of ​​the flexible circuit board.

[0038] Therefore, the bending characteristics and reliability of the flexible circuit board are improved.

[0039] The third pad portion is connected to the chip, and the fourth pad portion is connected to the display panel. The third and fourth pad portions extend in different directions. The fourth pad portion extends in a diagonal direction. The fourth pad portion extends in a diagonal direction.

[0040] Accordingly, the fourth pad portion can be connected to display panels having various sizes. In addition, the fourth pad portion can be connected to display panels having various terminal sizes.

[0041] Therefore, there is no need to use different flexible circuit boards depending on the size of the display panel. Accordingly, flexible circuit boards can be applied to display panels for various purposes.

[0042] Additionally, the flexible circuit board according to the embodiment includes a test pattern.

[0043] The flexible circuit board is connected to the display panel and the circuit board. The test pattern can measure the performance of the display panel. Therefore, the performance of the display panel can be verified before connecting the flexible circuit board and the display panel. This prevents COF module failure due to poor display panel performance after connecting the flexible circuit board, display panel, and circuit board.

[0044] The test pattern includes one pad portion connected to the display panel and another pad portion connected to the test device.

[0045] The line width of the other pad is larger than that of the first pad. The other pad is formed by removing the protective layer. Since the line width of the other pad is larger, the process of increasing the protective layer can be easily performed. This improves process efficiency. Furthermore, when removing the protective layer, other patterns can be prevented from being exposed outside the protective layer.

[0046] The test pattern is placed on the outermost side of the substrate. This prevents interference between the test pattern and the flexible circuit board when connecting the display panel.

[0047] Accordingly, the reliability and electrical characteristics of the flexible circuit board and COF module according to the embodiment are improved.

[0048] Figure 1 is a top view of a flexible circuit board according to the first embodiment.

[0049] Figure 2 is an enlarged view of area A of Figure 1.

[0050] Figures 3 and 4 are drawings for explaining the connection between the fourth pad portion and the terminal of the display panel when the fourth pad portion is a straight line.

[0051] Figures 5 and 6 are drawings for explaining the connection of the terminal of the fourth pad portion and the display panel when the fourth pad portion is diagonal.

[0052] Figures 7 and 8 are cross-sectional views taken along the AA' area of ​​Figure 1.

[0053] Figure 9 is a top view of a flexible circuit board according to the second embodiment.

[0054] Fig. 10 is a bottom view of a flexible circuit board according to the second embodiment.

[0055] Figure 11 is an enlarged view of area B of Figure 9.

[0056] Figure 12 is an enlarged view of area C of Figure 9.

[0057] Figure 13 is an enlarged view of area D of Figure 10.

[0058] Fig. 14 is a top view of a flexible circuit board according to the third embodiment.

[0059] Figures 15 and 16 are enlarged views of area A of Figure 14.

[0060] Fig. 17 is a top view of a flexible circuit board according to the fourth embodiment.

[0061] Fig. 18 is a bottom view of a flexible circuit board according to the fourth embodiment.

[0062] Figure 19 is an enlarged view of area B of Figure 17.

[0063] Figure 20 is an enlarged view of area C of Figure 18.

[0064] FIG. 21 and FIG. 22 are drawings for explaining the connection of a COF module and other members according to an embodiment.

[0065] FIGS. 23 to 25 are drawings of electronic devices including flexible circuit boards according to embodiments.

[0066] 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 the described embodiments, but may be implemented in various different forms. Within the scope of the technical concept of the present invention, one or more of the components of the embodiments may be selectively combined or substituted for use.

[0067] In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

[0068] In addition, 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 may also include the plural unless specifically stated in the phrase, and when it is described as “and (and) at least one (or more) of B, C,” it may include one or more of all combinations that can be combined with A, B, and C.

[0069] Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

[0070] And, when a component is described as being 'connected', 'coupled' or 'connected' to another component, it may include not only cases where the component is directly connected, coupled or connected to the other component, but also cases where the component is 'connected', 'coupled' or 'connected' by another component between the component and the other component.

[0071] Additionally, when it is described as being formed or disposed "above or below" each component, above or below includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or disposed between the two components.

[0072] Additionally, when expressed as “upper or lower,” it can include the meaning of not only the upward direction but also the downward direction based on one component.

[0073]

[0074] Below, with reference to the drawings, a flexible circuit board and a COF module including the same according to an embodiment are described.

[0075] Figures 1 to 8 are drawings for explaining a flexible circuit board according to a first embodiment. Figures 9 to 13 are drawings for explaining a flexible circuit board according to a second embodiment.

[0076] Referring to FIGS. 1 to 8, a flexible circuit board (1000) according to the first embodiment includes a substrate (100), a circuit pattern, and a protective layer (300).

[0077] The substrate (100) includes a first surface (1S) and a second surface (2S) opposite to the first surface (1S). A circuit pattern and a protective layer (300) are arranged on the first surface (1S).

[0078] The substrate (100) includes a cutting line (CL). The flexible circuit board (1000) is cut along the cutting line (CL). For example, a circuit pattern, a metal pattern, a protective layer, and chips are placed on the substrate (100). Thereafter, the substrate (100) is cut along the cutting line (CL). Accordingly, a COF module is manufactured. Accordingly, the edge of the COF module becomes the cutting line (CL).

[0079] The substrate (100) includes an effective area (AA) and an ineffective area (UA). In detail, the first surface (1S) includes an effective area (AA) and an ineffective area (UA).

[0080] The valid area (AA) and the invalid area (UA) are separated by the cutting line (CL). The valid area (AA) is the area inside the cutting line (CL). Furthermore, the invalid area (UA) is the area outside the cutting line (CL).

[0081] Circuit patterns, protective layers, and chips are placed on the active area (AA). In addition, dummy patterns and sprocket holes (SH) are placed on the inactive area (UA). The dummy patterns increase the strength of the substrate (100). In addition, the flexible circuit board (1000) is rolled or unrolled in a roll-to-roll manner by the sprocket holes (SH).

[0082] The substrate (100) includes a chip mounting area (CHA). The chip mounting area (CHA) is disposed on the first surface (1S). The chip mounting area (CHA) is disposed on the effective area (AA). A chip (CH) is disposed on the chip mounting area (CHA). In addition, pad portions of the circuit pattern are disposed inside the chip mounting area (CHA). In addition, the protective layer (300) is not disposed on the chip mounting area (CHA).

[0083] The substrate (100) comprises a flexible material. For example, the substrate (100) may comprise polyimide (PI). However, the embodiment is not limited thereto. The substrate (100) may comprise a polymer material, such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). Accordingly, the flexible circuit board can be applied to various electronic devices, including curved display devices.

[0084] The substrate (100) may have a thickness of 20 μm to 100 μm. For example, the substrate (100) may have a thickness of 25 μm to 50 μm. For example, the substrate (100) may have a thickness of 30 μm to 40 μm. If the thickness of the substrate (100) exceeds 100 μm, the overall thickness of the flexible circuit board increases. As a result, the flexible characteristics of the flexible circuit board may be reduced. In addition, if the thickness of the substrate (100) is less than 20 μm, the substrate (100) may be damaged by heat and pressure applied to the substrate (100) when mounting a chip on the flexible circuit board.

[0085] A circuit pattern and a protective layer (300) are disposed on a substrate (100). In detail, the circuit pattern and a protective layer (300) are disposed on a first surface (1S). In detail, the circuit pattern and a protective layer (300) are disposed on at least one of an active area (AA) and an inactive area (UA).

[0086] The circuit pattern includes a first circuit pattern (210) and a second circuit pattern (220).

[0087] Referring to FIG. 1, the first circuit pattern (210) includes a first wiring portion (211), a first pad portion (212a), and a second pad portion (212b). The first wiring portion (211), the first pad portion (212a), and the second pad portion (212b) may include the same material. In addition, the first wiring portion (211), the first pad portion (212a), and the second pad portion (212b) may be formed integrally.

[0088] The first pad portion (212a) is positioned within the chip mounting area (CHA). Accordingly, the first pad portion (212a) is connected to the terminal of the chip. As a result, the first circuit pattern (210) and the chip are connected.

[0089] The second pad portion (212b) is positioned outside the chip mounting area (CHA). The second pad portion (212b) is connected to the pad portion of the circuit board (3000). As a result, the first circuit pattern (210) and the circuit board (3000) are connected.

[0090] The first wiring section (211) is arranged between the first pad section (212a) and the second pad section (212b). The first wiring section (211) connects the first pad section (212a) and the second pad section (212b). Accordingly, the chip (CH) and the circuit board (3000) are connected. Accordingly, a signal generated from the chip (CH) is transmitted to the circuit board (3000).

[0091] The first circuit pattern (210) may further include a test pad portion. That is, the second pad portion (212b) may function as the first test pad portion.

[0092] Before connecting the circuit board and the second pad portion (212b), the first circuit pattern (210) can be tested by the first test pad portion. For example, whether the first circuit pattern is open or shorted can be checked through the first test pad portion.

[0093] The second circuit pattern (220) includes a second wiring portion (221), a third pad portion (222a), and a fourth pad portion (222b). The second wiring portion (221), the third pad portion (222a), and the fourth pad portion (222b) may include the same material. In addition, the second wiring portion (221), the third pad portion (222a), and the fourth pad portion (222b) may be formed integrally.

[0094] The third pad portion (222a) is positioned within the chip mounting area (CHA). Accordingly, the third pad portion (222a) is connected to the terminal of the chip. As a result, the second circuit pattern (220) and the chip (CH) are connected.

[0095] The fourth pad portion (222b) is positioned outside the chip mounting area (CHA). The fourth pad portion (222b) is connected to the pad portion of the external display panel (4000). As a result, the second circuit pattern (220) and the display panel (4000) are connected.

[0096] The second wiring section (221) is arranged between the third pad section (222a) and the fourth pad section (222b). The second wiring section (221) connects the third pad section (222a) and the fourth pad section (222b). Accordingly, the chip (CH) and the display panel (4000) are connected. Accordingly, a signal generated from the chip (CH) is transmitted to the display panel (4000).

[0097] The first circuit pattern (210) may further include a test pad portion. That is, the fourth pad portion (212b) may function as a second test pad portion.

[0098] Before connecting the display panel and the fourth pad portion (212b), the second circuit pattern (220) can be tested by the second test pad portion. For example, whether the second circuit pattern is open or shorted can be checked through the second test pad portion.

[0099] Although not shown in the drawing, the circuit pattern may further include a third circuit pattern. The third circuit pattern is not connected to the chip. The third circuit pattern is connected to the circuit board and the display panel.

[0100] The third circuit pattern may be a bypass circuit. For example, the third circuit pattern may be a power supply pattern. Accordingly, the circuit board and display panel may be powered by the third circuit pattern.

[0101] The line width and spacing of the third circuit pattern may be larger than the line width and spacing of the first and second circuit patterns (210, 220).

[0102] Although not shown in the drawing, at least one dummy pattern may be placed on the effective area (AA).

[0103] The dummy pattern can prevent the flexible circuit board (1000) from bending. In addition, the spacing and line width of the circuit pattern can be made uniform by the dummy pattern.

[0104] The dummy pattern may contain the same material as the circuit pattern. The line width of the dummy pattern may be the same as or different from the circuit pattern. The dummy pattern is not connected to the chip (CH), the circuit board (3000), and the display panel (4000).

[0105] The protective layer (300) is disposed on the first surface (1S). Accordingly, the protective layer (300) is disposed on the first circuit pattern (210), the second circuit pattern (220), and the third circuit pattern. The protective layer (300) is disposed on the first wiring portion (211) and the second wiring portion (221). The protective layer (300) is not disposed on the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), and the fourth pad portion (222b). In addition, the protective layer (300) is not disposed on the chip mounting area (CHA).

[0106] For example, the protective layer (300) includes a plurality of open areas. In addition, the substrate (100) includes a first side end and a second side end facing in the first direction.

[0107] At this time, the protective layer (300) includes a first open area corresponding to the chip mounting area (CHA). In addition, the protective layer (300) includes a second open area spaced apart from the first open area and positioned closer to the first side end of the substrate (100). In addition, the protective layer (300) includes a third open area spaced apart from the first and second open areas and positioned closer to the second side end of the substrate (100). At this time, the first open area may be defined as a chip mounting area (CHA) where a chip is placed. In addition, the second open area may be defined as a substrate connection area where a circuit board is connected. In addition, the third open area may be defined as a panel connection area where a display panel is connected. However, the embodiment is not limited thereto, and depending on the product design, the second open area may be defined as a panel connection area, and the third open area may be defined as a substrate connection area.

[0108] A flexible circuit board (1000) includes a bending area (BA). The flexible circuit board (1000) is bent in one direction on the bending area (BA). The flexible circuit board (1000) includes a separation area (IA). The separation area (IA) is an area between a chip mounting area (CHA) and a fourth pad portion (222b). The bending area (BA) is disposed on the separation area (IA).

[0109] The second circuit pattern (220) is placed on the separation area (IA). In detail, the second wiring portion (221) is placed on the separation area (IA).

[0110] The flexible circuit board (1000) includes a first direction (1D), a second direction (2D), and a third direction. The first direction (1D) is a direction in which the second pad portion (212b) and the fourth pad portion (222b) face each other. The second direction (2D) is a direction perpendicular to the first direction (1D). The third direction is a direction between the first direction (1D) and the second direction (2D).

[0111] The second wiring section (221) extends in multiple directions. For example, the second wiring section (221) may include a second-first wiring section and a second-second wiring section. The second-first wiring section extends in the first direction (1D). That is, the second-first wiring section extends in a straight line. The second-second wiring section extends in a third direction. That is, the second-second wiring section extends diagonally.

[0112] Accordingly, a second wiring section (221) extending in multiple directions is arranged on the separation area (IA). A second-first wiring section may be arranged on the bending area (BA). For this purpose, the second-first wiring section may have a set length.

[0113] In detail, the length of the 2-1 wiring portion may be 1000 µm to 3000 µm, 1500 µm to 2800 µm, or 2300 µm to 2600 µm. Accordingly, the 2nd wiring portion (221) can sufficiently secure the length of the 2-1 wiring portion extending in a straight direction. Accordingly, most of the 2nd wiring portions on the bending area (BA) may be the 2-1 wiring portions. Alternatively, all of the 2nd wiring portions on the bending area (BA) may be the 2-1 wiring portions.

[0114] The bending area (BA) bends in one direction. Accordingly, if the direction in which the flexible circuit board is bent and the direction in which the second wiring section extends are at an angle, the bending characteristics of the flexible circuit board may be reduced.

[0115] Additionally, stress is generated on the bending area (BA). The second wiring portion may be stretched by the stress. If the second wiring portion is arranged diagonally, the stress may extend in the first direction, causing the second wiring portion to peel off.

[0116] Accordingly, the flexible circuit board is formed with the length of the second-first wiring section within a set range. Accordingly, most or all of the second wiring section on the bending area extends in the first direction. Consequently, the bending characteristics and reliability of the flexible circuit board are improved.

[0117] The fourth pad portion (222b) extends in multiple directions. The fourth pad portion (222b) may extend in a different direction from the second wiring portion (221). The fourth pad portion (222b) extends in a different direction from the third pad portion (222a). The fourth pad portion (222b) extends in a different direction from at least one of the first pad portion (212a) and the second pad portion (212b).

[0118] The fourth pad portion (222b) may extend in the third direction. Alternatively, the fourth pad portion (222b) may extend in the first direction (1D) and the third direction. That is, at least one fourth pad portion may extend in the third direction.

[0119] Referring to FIGS. 1 and 2, the fourth pad portion (222b) can extend in the first direction (1D) and the third direction. The fourth pad portion (222b) is connected to the second wiring portion (221). The second wiring portion (221) includes one central wiring portion and an outer wiring portion. The outer wiring portion can be arranged on the left and right of the central wiring portion in the second direction (2D).

[0120] Accordingly, the fourth pad portion (222b) may include one central pad portion (CP) and multiple outer pad portions. The outer pad portion may include multiple first outer pad portions (OP1) and multiple second outer pad portions (OP2). The first outer pad portion (OP1) is arranged to the left of the central pad portion (CP). The second outer pad portion (OP2) is arranged to the right of the central pad portion (CP).

[0121] The central pad portion (CP) extends in a first direction (1D). The first outer pad portion (OP1) and the second outer pad portion (OP2) extend in a third direction. The outer pad portions (OP1, OP2) can be arranged symmetrically left and right by the central pad portion (CP).

[0122] The first outer pad portion (OP1) and the second outer pad portion (OP2) are inclined. That is, the first outer pad portion (OP1) and the second outer pad portion (OP2) are arranged diagonally.

[0123] The inclination angles of the first outer pad portions (OP1) may vary as they extend in the second direction (2D). The inclination angles of the first outer pad portions (OP1) may vary as they extend away from the central pad portion (CP). The inclination angle of the first outer pad portion (OP1) is the angle formed by the central pad portion (CP) and the first outer pad portion (OP1). In detail, the inclination angles of the first outer pad portions (OP1) may increase as they extend away from the central pad portion (CP).

[0124] The inclination angle of the first outer pad portions (OP1) may be different from the inclination angle of the second-second wiring portion. The inclination angle of the second-second wiring portion is the angle formed by the second-first wiring portion and the second-second wiring portion. In detail, the maximum inclination angle of the first outer pad portions (OP1) may be smaller than the maximum inclination angle of the second-second wiring portion.

[0125] The inclination angles of the second outer pad portions (OP2) can vary as they extend in the second direction (2D). The inclination angle of the second outer pad portion (OP2) is the angle formed by the central pad portion (CP) and the second outer pad portion (OP2). Specifically, the inclination angles of the second outer pad portions (OP2) can increase as they extend in the second direction (2D).

[0126] The inclination angles of the second outer pad portions (OP2) may be different from the inclination angles of the second-second wiring portions. In detail, the maximum inclination angles of the second outer pad portions (OP2) may be smaller than the maximum inclination angles of the second-second wiring portions.

[0127] Since the first outer pad portion (OP1) and the second outer pad portion (OP1) are arranged diagonally, they can be easily connected to terminals of various display panels.

[0128] Figures 3 to 6 are drawings for explaining the connection between the fourth pad portion (222b) and the terminal (DP) of the display panel according to the extension direction of the fourth pad portion (222b).

[0129] Referring to FIGS. 3 and 4, the fourth pad portion (222b) extends in a straight line. Referring to FIGS. 3 and 4 (a), the sizes of the flexible circuit board and the display panel may be the same or similar. In detail, the width (W1) of the pad portion area where the fourth pad portion is arranged and the width (W2) of the terminal area where the terminal is arranged may be the same or similar. In this case, both the fourth pad portion (222b) and the terminal (DP) may be connected.

[0130] Referring to (b) and (c) of FIGS. 3 and 4, the sizes of the flexible circuit board and the display panel may be different. Specifically, the width (W1) of the pad area and the width (W2) of the terminal area may be different.

[0131] Referring to (b) of FIG. 3 and FIG. 4, the width (W1) of the pad area may be smaller than the width (W2) of the terminal area. In this case, the fourth pad area (222b) and the terminal (DP) are not all connected. That is, due to the line width difference between the fourth pad area (222b) and the terminal (DP), some of the pad areas and some of the terminals are not connected.

[0132] Referring to (c) of FIG. 3 and FIG. 4, the width (W1) of the pad area may be greater than the width (W2) of the terminal area. In this case, the fourth pad area (222b) and the terminal (DP) are not all connected. That is, due to the line width difference between the fourth pad area (222b) and the terminal (DP), some of the pad areas and some of the terminals are not connected.

[0133] The embodiment solves the above problem by controlling the extension direction of the fourth pad portion (222b). Specifically, the fourth pad portion (222b) of the embodiment extends in a diagonal direction.

[0134] Referring to FIGS. 5 and 6, the fourth pad portion (222b) extends diagonally. Referring to FIGS. 5 and 6 (a), the sizes of the flexible circuit board and the display panel may be the same or similar. Specifically, the width (W1) of the pad portion area and the width (W2) of the terminal area may be the same or similar. In this case, both the fourth pad portion (222b) and the terminal (DP) may be connected.

[0135] Referring to (b) and (c) of FIGS. 5 and 6, the sizes of the flexible circuit board and the display panel may be different. Specifically, the width (W1) of the pad area and the width (W2) of the terminal area may be different.

[0136] Referring to (b) of FIGS. 5 and 6, the width (W1) of the pad area may be smaller than the width (W2) of the terminal area. In this case, both the fourth pad area (222b) and the terminal area (DP) are connected. The fourth pad area (222b) extends in a diagonal direction. Therefore, the portion where the fourth pad area and the terminal area (DP) intersect is also covered by the fourth pad area (222b). Therefore, even when the line width of the terminal area (DP) is larger than the line width of the fourth pad area (222b), both the fourth pad area (222b) and the terminal area (DP) are connected.

[0137] Referring to (c) of FIGS. 5 and 6, the width (W1) of the pad area may be greater than the width (W2) of the terminal area. In this case, both the fourth pad area (222b) and the terminal area (DP) are connected. The fourth pad area (222b) extends in a diagonal direction. Therefore, the portion where the fourth pad area and the terminal area (DP) intersect is also covered by the fourth pad area (222b). Therefore, even when the line width of the terminal area (DP) is smaller than the line width of the fourth pad area (222b), both the fourth pad area (222b) and the terminal area (DP) are connected.

[0138] Accordingly, the flexible circuit board according to the embodiment can eliminate bonding defects between the flexible circuit board and the display panel even if the sizes of the fourth pad portion (222b) and the terminal (DP) of the display panel are different.

[0139] In addition, even if the width of the pad area (W1) and the width of the terminal area (W2) differ from the design dimensions due to the difference in shrinkage rate between the flexible circuit board and the display during the connection process between the fourth pad area (222b) and the terminal (DP) of the display panel, this can be compensated for and bonding defects can be eliminated.

[0140] In practice, the fourth pad portion (222b) is not limited to facilitating connection with the display panel when it is diagonal. The second pad portion (212b) may also be formed diagonally. That is, by forming at least one of the second pad portion (212b) and the fourth pad portion (222b) diagonally, bonding defects between the display panel and the circuit board can be reduced. By forming both the second pad portion (212b) and the fourth pad portion (222b) diagonally, bonding defects between the display panel and the circuit board can be reduced. Since the terminal pitch of the circuit board is larger than the terminal pitch of the display panel, the fourth pad portion (222b) may be formed diagonally, and the second pad portion (212b) may be formed in a straight line in order to reduce the overall width of the flexible circuit board.

[0141] A flexible circuit board according to an embodiment includes a second circuit pattern connected to a display panel and a chip. The second circuit pattern includes a second wiring portion, a third pad portion, and a fourth pad portion.

[0142] The second wiring section includes a second wiring section 2-1 and a second wiring section 2-2. The second wiring section 2-1 extends in a linear direction, and the second wiring section 2-2 extends in a diagonal direction. The second wiring section 2-1 has a length within a set range. Therefore, the second wiring section 2-1 is arranged mostly or entirely on the bending area of ​​the flexible circuit board.

[0143] Therefore, the bending characteristics and reliability of the flexible circuit board are improved.

[0144] The third pad portion is connected to the chip, and the fourth pad portion is connected to the display panel. The third and fourth pad portions extend in different directions. The fourth pad portion extends in a diagonal direction. The fourth pad portion extends in a diagonal direction.

[0145] Accordingly, the fourth pad portion can be connected to display panels having various sizes. In addition, the fourth pad portion can be connected to display panels having various terminal sizes.

[0146] Therefore, there is no need to use different flexible circuit boards depending on the size of the display panel. Accordingly, flexible circuit boards can be applied to display panels for various purposes.

[0147] Referring to FIGS. 7 and 8, the circuit pattern is formed in a multilayer structure. FIGS. 7 and 8 are described focusing on the first circuit pattern. The following description applies equally to the second and third circuit patterns.

[0148] Referring to Fig. 7, the first circuit pattern is formed in multiple layers. In detail, the first wiring portion (211), the first pad portion (212a), and the second pad portion (212b) include a buffer layer (205), a metal layer (201), and a bonding layer (203).

[0149] The buffer layer (205) may include multiple layers. Specifically, the buffer layer (205) includes a first buffer layer (205a) and a second buffer layer (205b). The first buffer layer (205a) is disposed on the substrate (100). The second buffer layer (205b) is disposed on the first buffer layer (205a).

[0150] The first buffer layer (205a) includes a material having good adhesion to the substrate (100). For example, the first buffer layer (205a) may include nickel (Ni). In addition, the second buffer layer (205b) includes a material having good adhesion to the circuit pattern. For example, the second buffer layer (205b) may include chromium (Cr).

[0151] The buffer layer (205) may have a thin film thickness in nanometer units. For example, the buffer layer (205) may have a thickness of 20 nm or less.

[0152] The adhesion between the substrate (100) and the circuit pattern is improved by the buffer layer (205).

[0153] The metal layer (201) is disposed on the buffer layer (205). Specifically, the metal layer (201) is disposed on the second buffer layer (205b). The metal layer (201) includes a metal material. For example, the metal layer (201) may include copper (Cu).

[0154] The metal layer (201) can be formed by electroplating using the buffer layer as a seed layer. That is, the metal layer (201) can be a plating layer.

[0155] The thickness of the metal layer (201) may be 5 µm to 30 µm.

[0156] The bonding layer (203) is placed on the metal layer (201).

[0157] The bonding layer (203) is disposed on the side and upper surface of the metal layer (201). For example, the bonding layer (203) may be disposed to surround the metal layer (201).

[0158] The bonding layer (203) includes a metal. For example, the bonding layer (203) may include tin (Sn). The bonding layer (203) is formed by a plating process. In detail, the bonding layer (203) may be a plating layer.

[0159] The thickness of the bonding layer (203) may be 0.3 μm to 0.7 μm. The tin content may increase as it extends from the lower surface to the upper surface of the bonding layer (203).

[0160] That is, the bonding layer (203) is in contact with the metal layer (201). Therefore, the tin content increases from the lower surface of the bonding layer (203) toward the upper surface. Additionally, the copper content decreases from the lower surface of the bonding layer (203) toward the upper surface.

[0161] Accordingly, pure tin may remain in a thickness range of 0.1 μm to 0.3 μm from the upper surface of the bonding layer (203).

[0162] The pad portion can be easily bonded to terminals of chips, circuit boards, and display panels by the bonding layer (203). For example, when heat and pressure are applied to the pad portion, the upper surface of the bonding layer melts. Pure tin remains on the upper surface of the bonding layer. Therefore, the pad portion can be easily bonded to terminals of chips, circuit boards, and display panels.

[0163] Referring to Fig. 8, the metal layer (201) may include a first metal layer (201a) and a second metal layer (201b). The first metal layer (201a) is disposed on the buffer layer (205). The second metal layer (201b) is disposed on the first metal layer (201a). The second metal layer (201b) may be formed by electroplating using the first metal layer (201a) as a seed layer. That is, the second metal layer (201b) may be a plating layer.

[0164] The thickness of the first metal layer (201a) may be smaller than the thickness of the second metal layer (201b).

[0165] For example, the thickness of the first metal layer (201a) may be 0.7 μm to 2 μm, and the thickness of the second metal layer (201b) may be 5 μm to 25 μm.

[0166] The first metal layer (201a) and the second metal layer (201b) may include the same metal material. For example, the first metal layer (201a) and the second metal layer (201b) may include copper (Cu).

[0167] The bonding layer (203) may include a first bonding layer (203a) and a second bonding layer (203b).

[0168] The first bonding layer (203a) is disposed on the metal layer (201). In detail, the first bonding layer (203a) is disposed on the first wiring portion (211), the first pad portion (212a), and the second pad portion (212b).

[0169] The second bonding layer (203b) is disposed on the first bonding layer (203a). In detail, the second bonding layer (203b) is disposed on the first pad portion (212a) and the second pad portion (212b).

[0170] Accordingly, the first wiring portion (211) includes a buffer layer (205), a metal layer (201), and a first bonding layer (203a). In addition, the first pad portion (212a) and the second pad portion (212b) include a buffer layer (205), a metal layer (201), a first bonding layer (203a), and a second bonding layer (203b).

[0171] Therefore, the layer structure of the first wiring section (211) is different from the layer structures of the first pad section (212a) and the second pad section (212b).

[0172] The first bonding layer (203a) and the second bonding layer (203b) contain metal. In detail, the first bonding layer (203a) and the second bonding layer (203b) may contain tin (Sn).

[0173] The first bonding layer (203a) and the second bonding layer (203b) are arranged with different thicknesses. In detail, the thickness of the second bonding layer (203b) is greater than the thickness of the first bonding layer (203a).

[0174] For example, the first bonding layer (203a) has a thickness of 0.02 μm to 0.06 μm. Additionally, the second bonding layer (203b) has a thickness of 0.2 μm to 0.6 μm.

[0175] Accordingly, the thickness of the first wiring portion (211) is reduced. The flexible circuit board includes a bending area (BA) that bends in one area. The wiring portion is arranged on the bending area (BA). Accordingly, the thickness of the bonding layer on the wiring portion is formed to be small. Accordingly, when the flexible circuit board is bent, cracks can be prevented from forming in the first wiring portion (211).

[0176] The thickness of the circuit pattern may be greater than 5 μm to 25 μm. In detail, the thickness of the circuit pattern may be 6 μm to 20 μm. In detail, the thickness of the circuit pattern may be 7 μm to 15 μm.

[0177] If the circuit pattern thickness is less than 5 μm, the circuit pattern resistance may increase. If the circuit pattern thickness exceeds 25 μm, it becomes difficult to implement a fine pattern.

[0178] Hereinafter, a flexible circuit board according to a second embodiment will be described with reference to FIGS. 9 to 13. Descriptions identical or similar to those of the first embodiment described above will be omitted.

[0179] The first direction (1D) is the direction in which the fourth pad portion (222b) and the sixth pad portion (232b) face each other. The second direction (2D) is a direction perpendicular to the first direction (1D). The third direction is a direction between the first direction (1D) and the second direction (2D).

[0180] A flexible circuit board according to the second embodiment includes a substrate (100), a circuit pattern, and a protective layer.

[0181] The circuit pattern includes a first circuit pattern (210), a second circuit pattern (220), and a third circuit pattern (230).

[0182] The first circuit pattern (210) is arranged on the first surface (1S). The second circuit pattern (220) is arranged on the first surface (1S) and the second surface (2S). The third circuit pattern (230) is arranged on the first surface (1S) and the second surface (2S).

[0183] The first circuit pattern (210) is identical to the first circuit pattern of the first embodiment.

[0184] A second circuit pattern (220) is arranged on the first surface (1S) and the second surface (2S). The second circuit pattern (220) includes a second wiring portion (221a, 221b), a third pad portion (222a), a fourth pad portion (222b), and a first via (V1). The second wiring portion (221a, 221b), the third pad portion (222a), and the fourth pad portion (222b) may include the same material. In addition, the second wiring portion (221a, 221b), the third pad portion (222a), and the fourth pad portion (222b) may be formed integrally.

[0185] A first protective layer (310) and a second protective layer (320) are respectively disposed on the second wiring portions (221a, 221b). The first protective layer (310) and the second protective layer (320) are not disposed on the third pad portion (222a) and the fourth pad portion (222b).

[0186] The third pad portion (222a) is positioned on the first surface (1S). The third pad portion (222a) is positioned within the chip mounting area (CHA). Accordingly, the third pad portion (222a) is connected to the terminal of the chip. As a result, the second circuit pattern (220) and the chip are connected.

[0187] The fourth pad portion (222b) is positioned on the second surface (2S). The fourth pad portion (222b) is connected to a terminal of an external display panel. As a result, the second circuit pattern (220) and the display panel are connected.

[0188] The second wiring section includes a second-first wiring section (221a) and a second-second wiring section (221b). The second-first wiring section (221a) is disposed on the first surface (1S). The second-second wiring section (221b) is disposed on the second surface (2S). The second wiring sections (221a, 221b) connect the third pad section (222a) and the fourth pad section (222b). Specifically, the second-first wiring section (221a) is connected to the third pad section (222a). The second-second wiring section (221b) is connected to the fourth pad section (222b).

[0189] Accordingly, the chip and the display panel are connected. Therefore, signals generated from the chip are transmitted to the display panel.

[0190] A first protective layer (310) and a second protective layer (320) are disposed on the second circuit pattern (220). Specifically, the first protective layer (310) is disposed on the second circuit pattern (220) on the first surface (1S). The second protective layer (320) is disposed on the second circuit pattern (220) on the second surface (2S). The first protective layer (310) and the second protective layer (320) are not disposed on the third pad portion (222a) and the fourth pad portion (222b).

[0191] The 2-1 wiring portion (221a) and the 2-2 wiring portion (221b) are connected. The 2-1 wiring portion (221a) and the 2-2 wiring portion (221b) are connected through a first via (V1). The first via (V1) penetrates the first surface (1S) and the second surface (2S). Accordingly, the first via (V1) is arranged on the first surface (1S) and the second surface (2S). The first via (V1) on the first surface (1S) and the first via (V1) on the second surface (2S) are arranged at positions corresponding to each other.

[0192] The first via (V1) includes a first via land (VL1) and a first via hole (VH1). The first via hole (VH1) is formed inside the first via land (VL1). The first via land (VL1) includes the same material as the second wiring portions (221a, 221b). A conductive material is disposed in the first via hole (VH1). Accordingly, the second-first wiring portion (221a) and the second-second wiring portion (221b) are electrically connected.

[0193] A third circuit pattern (230) is arranged on the first surface (1S) and the second surface (2S). The third circuit pattern (230) includes a third wiring portion (231), a fifth pad portion (232a), a sixth pad portion (232b), and a second via (V2). The third wiring portion (231), the fifth pad portion (232a), and the sixth pad portion (232b) may include the same material. In addition, the third wiring portion (231), the fifth pad portion (232a), and the sixth pad portion (232b) may be formed integrally.

[0194] The fifth pad portion (232a) is positioned on the first surface (1S). The fifth pad portion (232a) is positioned within the chip mounting area (CHA). Accordingly, the fifth pad portion (232a) is connected to the terminal of the chip. As a result, the third circuit pattern (230) and the chip are connected.

[0195] The sixth pad portion (232b) is positioned on the second surface (2S). The sixth pad portion (232b) is connected to a terminal of the display panel. Thus, the third circuit pattern (230) and the display panel are connected.

[0196] The third wiring section (231) is positioned on the second surface (2S). The third wiring section (231) connects the fifth pad section (232a) and the sixth pad section (232b). Accordingly, the chip and the display panel are connected. Accordingly, signals generated from the chip are transmitted to the display panel.

[0197] A second protective layer (320) is disposed on the third circuit pattern (230). The second protective layer (320) is disposed on the third circuit pattern (230) on the second surface (2S). The second protective layer (320) is not disposed on the sixth pad portion (232b).

[0198] The fifth pad portion (232a) and the third wiring portion (231) are connected. In detail, the fifth pad portion (232a) and the third wiring portion (231) are connected through the second via (V2). The second via (V2) penetrates the first surface (1S) and the second surface (2S). Accordingly, the second via (V2) is arranged on the first surface (1S) and the second surface (2S). The second via (V2) on the first surface (1S) and the second via (V2) on the second surface (2S) are arranged at positions corresponding to each other.

[0199] The second via (V2) includes a second via land (VL2) and a second via hole (VH2). The second via land (VL2) includes the same material as the third wiring portion (231). The second via hole (VH2) is formed inside the second via land (VL2). A conductive material is disposed in the second via hole (VH2). Accordingly, the fifth pad portion (232a) and the third wiring portion (231) are electrically connected.

[0200] At least one of the fourth pad portion (222b) and the sixth pad portion (232b) extends in multiple directions. Specifically, the fourth pad portion (222b) and the sixth pad portion (232b) can extend in a different direction from the second wiring portion (221) and the third wiring portion (231). The fourth pad portion (222b) and the sixth pad portion (232b) extend in a different direction from the third pad portion (222a) and the fifth pad portion (232a). The fourth pad portion (222b) and the sixth pad portion (232b) extend in a different direction from at least one of the first pad portion (212a) and the second pad portion (212b).

[0201] The fourth pad portion (222b) and the sixth pad portion (232b) may extend in the third direction. Alternatively, the fourth pad portion (222b) and the sixth pad portion (232b) may extend in the first direction (1D) and the third direction.

[0202] Referring to FIG. 13, the fourth pad portion (222b) and the sixth pad portion (232b) can extend in the first direction (1D) and the third direction.

[0203] The fourth pad portion (222b) and the sixth pad portion (232b) may include one central pad portion (CP) and a plurality of outer pad portions (OP). The outer pad portions (OP) are arranged in the left and right directions of the central pad portion (CP).

[0204] The central pad portion (CP) extends in the first direction (1D). The outer pad portion (OP) extends in the third direction. The outer pad portion (OP) can be arranged symmetrically left and right by the central pad portion (CP).

[0205] The outer pad portion (OP) is inclined. That is, the outer pad portion (OP) is arranged diagonally. For example, the outer pad portion (OP) may be inclined in a direction that increases width or decreases width. Specifically, the outer pad portion (OP) may be inclined in a direction that increases or decreases the distance between the outermost pad portions.

[0206] The inclination angle of the outer pad portions (OP) can vary as it extends in the second direction (2D). The inclination angle of the outer pad portion (OP) is the angle formed by the central pad portion (CP) and the outer pad portion (OP). Specifically, the inclination angle of the outer pad portions (OP) can increase as it extends in the second direction (2D).

[0207] The second wiring section and the third wiring section extend in multiple directions.

[0208] The inclination angles of the outer pad portions (OP) may be different from the inclination angles of the second wiring portion and the third wiring portion. In detail, the maximum inclination angle of the outer pad portions (OP) may be smaller than at least one of the maximum inclination angles of the second wiring portion and the maximum inclination angles of the third wiring portion.

[0209] Since the outer pad portion (OP) is arranged diagonally, it can be easily connected to terminals of various display panels.

[0210] That is, even if the line width of the terminal (DP) is larger than the line widths of the fourth pad portion (222b) and the sixth pad portion (232b), as described above, the fourth pad portion (222b) and the sixth pad portion (232b) are both connected to the terminal (DP).

[0211] Additionally, even if the line width of the terminal (DP) is smaller than the line width of the fourth pad portion (222b) and the sixth pad portion (232b), both the fourth pad portion (222b) and the sixth pad portion (232b) are connected to the terminal (DP).

[0212] Accordingly, the fourth pad portion and the sixth pad portion can be connected to display panels having various sizes. In addition, the fourth pad portion and the sixth pad portion can be connected to display panels having various terminal sizes.

[0213] Therefore, there is no need to use different flexible circuit boards depending on the size of the display panel. Accordingly, flexible circuit boards can be applied to display panels for various purposes.

[0214] Fig. 14 is a top view of a flexible circuit board according to the third embodiment, Figs. 15 and 16 are enlarged views of area A of Fig. 14, Fig. 17 is a top view of a flexible circuit board according to the fourth embodiment, Fig. 18 is a bottom view of a flexible circuit board according to the fourth embodiment, and Fig. 19 is an enlarged view of area B of Fig. 17.

[0215] Hereinafter, a description will be given based on a structure different from that of the flexible circuit boards of the first and second embodiments described with reference to FIGS. 1 to 13. At this time, in the flexible circuit boards of the third and fourth embodiments, components that are substantially the same as those of the first and second flexible circuit boards will be described with the same reference numerals.

[0216] The third and fourth embodiments described below are described based on a structure in which the outer pad portions are arranged in a straight line rather than diagonally. However, the embodiments are not limited thereto, and the outer pad portions provided in the flexible circuit boards of the third and fourth embodiments described below may be provided with a diagonal structure and a certain inclination angle as illustrated in FIGS. 1 to 13.

[0217] Referring to FIG. 14, the flexible circuit board of the third embodiment further includes a test pattern (240).

[0218] A test pattern (240) is placed on the first surface (1S). The test pattern (240) is placed on the effective area (AA). The test pattern (240) is placed adjacent to the second circuit pattern (220). The test pattern (240) is placed adjacent to the edge of the substrate (100). For example, the test pattern (240) may be a pattern placed on the outermost side of the substrate (100).

[0219] The test pattern (240) includes a seventh pad portion (242a), an eighth pad portion (242b), and a fourth wiring portion (241).

[0220] The seventh pad portion (242a) is positioned outside the chip mounting area (CHA). The seventh pad portion (242a) is positioned adjacent to the second wiring portion (221).

[0221] The eighth pad portion (242b) is positioned outside the chip mounting area (CHA). The eighth pad portion (242b) is positioned adjacent to the fourth pad portion (222b).

[0222] The fourth wiring section (241) connects the seventh pad section (242a) and the eighth pad section (242b). The seventh pad section (242a), the eighth pad section (242b), and the fourth wiring section (241) can be formed integrally.

[0223] The eighth pad portion (242b) is connected to a terminal of the display panel. Accordingly, the size of the eighth pad portion (242b) may be the same as or similar to that of the fourth pad portion (222b).

[0224] The seventh pad section (242a) contacts an external test device. The test device measures the performance of the display panel. Specifically, the display panel is connected to the eighth pad section (242b), and the performance of the display panel is tested through the seventh pad section (242a). In other words, the test pattern may be a pattern that tests the performance of the display panel.

[0225] Referring to Fig. 15, the protective layer (300) is not disposed on the seventh pad portion (242a). For example, after the test pattern (240) is disposed on the substrate (100), the protective layer (300) may be disposed on the test pattern (240). The protective layer (300) is not disposed on the eighth pad portion (242b). The protective layer (300) is disposed on the seventh pad portion (242a) and the fourth wiring portion (241).

[0226] Next, when measuring the performance of the display panel, the protective layer (300) on the seventh pad portion (242a) is removed. Accordingly, the seventh pad portion (242a) is exposed to the outside of the protective layer (300).

[0227] Referring to FIG. 16, a protective layer (300) may be partially disposed on the seventh pad portion (242a). In detail, during the process of removing the protective layer (300), some of the protective layer may remain on the seventh pad portion (242a). Accordingly, the seventh pad portion (242a) may include a first region (242a1) and a second region (242a2). The protective layer (300) is not disposed on the first region (242a1). The protective layer (300) is disposed on the second region (242a2).

[0228] The area of ​​the first region (242a1) may be larger than the area of ​​the second region (242a2). For example, the area of ​​the first region (242a1) may be 50% or more of the area of ​​the seventh pad portion (242a). In detail, the area of ​​the first region (242a1) may be 50% to 99%, 70% to 99%, 80% to 99%, 85% to 95%, or 88% to 92% of the area of ​​the seventh pad portion (242a).

[0229] If the area of ​​the first region (242a1) is less than 50% of the area of ​​the seventh pad portion (242a), the contact area between the test device and the seventh pad portion (242b) may decrease. Accordingly, a measurement error of the test device may occur. If the area of ​​the first region (242a1) exceeds 99% of the area of ​​the seventh pad portion (242a), the protective layer (300) outside the seventh pad portion (242a) may be removed due to a process error. Accordingly, other circuit patterns or dummy patterns may be exposed to the outside of the protective layer. Accordingly, the circuit pattern or dummy pattern may be corroded. Accordingly, the reliability of the flexible circuit board may decrease.

[0230] The sizes of the 7th pad section (242a) and the 8th pad section (242b) are different.

[0231] The eighth pad portion (242b) may be similar in size to the fourth pad portion (222b) because it is connected to the display panel. Specifically, the line widths of the eighth pad portion (242b) and the fourth pad portion (222b) are the same or similar. Accordingly, when forming circuit patterns and test patterns, etching uniformity can be improved.

[0232] The line width (W1) of the seventh pad portion (242a) is different from the line width (W2) of the eighth pad portion (242b). Specifically, the line width of the seventh pad portion (242a) is larger than the line width of the eighth pad portion (242b). In addition, the line width of the seventh pad portion (242a) is larger than the maximum line width of the fourth wiring portion.

[0233] The seventh pad portion (242a) requires a process for removing the protective layer (300). If the size of the seventh pad portion (242a) is small, the protective layer (300) must be removed in fine pieces. Accordingly, process efficiency is reduced, and the protective layer outside the seventh pad portion (242a) may be removed.

[0234] Additionally, if the size of the seventh pad portion (242a) is small, the contact area between the test device and the seventh pad portion (242a) decreases. Consequently, measurement errors in the test device may occur. This makes it difficult to measure the performance of the display panel.

[0235] Additionally, the line width of the seventh pad portion (242a) may be larger than the spacing of at least one of the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), and the fourth pad portion (222b). In detail, the line width of the seventh pad portion (242a) may be larger than the spacing of each of the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), and the fourth pad portion (222b).

[0236] Additionally, the line width of the seventh pad portion (242a) may be larger than the line width of at least one of the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), and the fourth pad portion (222b). In detail, the line width of the seventh pad portion (242a) may be larger than the line widths of the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), and the fourth pad portion (222b).

[0237] The shapes of the 7th pad portion (242a) and the 8th pad portion (242b) may be the same or different.

[0238] Referring to FIGS. 15 and 16, the seventh pad portion (242a) has a circular shape, and the eighth pad portion (242b) has a rectangular shape. However, the embodiment is not limited thereto. The shapes of the seventh pad portion (242a) and the eighth pad portion (242b) may be the same.

[0239] Additionally, the seventh pad portion (242a) can be formed in various shapes other than a circular shape. Accordingly, the shape of the seventh pad portion (242a) can vary depending on the method of removing the protective layer (300). Accordingly, the protective layer on the seventh pad portion (242a) can be easily removed.

[0240] In FIGS. 14 to 16, two test patterns (240) facing each other in the second direction (2D) are illustrated. However, the implementation is not limited thereto. The test pattern (240) may include one test pattern (240). Alternatively, the test pattern (240) may include three or more test patterns (240).

[0241] The line width of the fourth wiring section (241) may be the same as or similar to the line width of at least one of the first wiring section (211) and the second wiring section (221). Accordingly, when forming a circuit pattern and a test pattern, etching uniformity may be improved.

[0242]

[0243] Meanwhile, referring to FIGS. 17 to 19, a flexible circuit board according to a fourth embodiment includes a substrate (100), a circuit pattern, a test pattern, and a protective layer. A test pattern (240) is disposed on a first side (1S) and a second side (2S) of the substrate (100). The test pattern (240) is disposed on an effective area (AA). The test pattern (240) is disposed adjacent to a second circuit pattern (220) and a third circuit pattern (230). The test pattern (240) is disposed adjacent to an edge of the substrate (100). The test pattern (240) is disposed closer to the edge of the substrate than the second and third circuit patterns. For example, the test pattern (240) may be a pattern disposed on the outermost side of the substrate (100).

[0244] The test pattern (240) includes a plurality of seventh pad portions (242a3, 242a4), a plurality of eighth pad portions (242b1, 242b2), a plurality of fourth wiring portions (241a, 241b), and a plurality of third vias (V3a, V3b).

[0245] For example, the 7th pad portion includes a 7-1st pad portion (242a3) and a 7-2nd pad portion (242a4). The 7-1st pad portion (242a3) and the 7-2nd pad portion (242a4) are spaced apart in the first direction (1D) or the second direction (2D).

[0246] The 7-1 pad portion (242a3) and the 7-2 pad portion (242a4) may each include a first region (242a1) and a second region (242a2). The first protective layer (310) is not disposed on the first region (242a1). The first protective layer (310) is disposed on the second region (242a2).

[0247] The fourth wiring section includes a 4-1 wiring section (241a) and a 4-2 wiring section (241b). The 4-1 wiring section (241a) is arranged on the first surface (1S). The 4-2 wiring section (241b) is arranged on the second surface (2S).

[0248] The 8th pad section includes an 8-1 pad section (242b1) and an 8-2 pad section (242b2). The 8-1 pad section (242b1) and the 8-2 pad section (242b2) are spaced apart in the first direction (1D) or the second direction (2D).

[0249] The 8-1 pad section (242b1) is positioned adjacent to the 4th pad section (222b). The 8-2 pad section (242b2) is positioned adjacent to the 6th pad section (232b).

[0250] The third via includes a third-first via (V3a) and a third-second via (V3b). The third-first via (V3a) and the third-second via (V3b) are spaced apart in the first direction (1D) or the second direction (2D). The fourth-first wiring portion (241a) and the fourth-second wiring portion (241b) are connected via the third-first via (V3a) and the third-second via (V3b).

[0251] The 7-1 pad portion (242a3) and the 8-1 pad portion (242b1) are connected. In detail, the 7-1 pad portion (242a3) and the 8-1 pad portion (242b1) are connected through the 4-1 wiring portion (241a), the 4-2 wiring portion (241b), and the 3-1 via (V3a).

[0252] The 7-2 pad portion (242a4) and the 8-2 pad portion (242b2) are connected. In detail, the 7-2 pad portion (242a4) and the 8-2 pad portion (242b2) are connected through the 4-1 wiring portion (241a), the 4-2 wiring portion (241b), and the 3-2 via (V3b).

[0253] The 8-1 pad portion (242b1) and the 8-2 pad portion (242b2) are connected to terminals of the display panel. Accordingly, the size of the 8-1 pad portion (242b1) may be the same as or similar to the 4th pad portion (222b). In addition, the size of the 8-2 pad portion (242b2) may be the same as or similar to the 6th pad portion (232b).

[0254] The 7-1 pad portion (242a3) and the 7-2 pad portion (242a4) are in contact with an external test device. The test device measures the performance of the display panel. Specifically, the display panel is connected to the 8-1 pad portion (242b1) and the 8-2 pad portion (242b2), and the performance of the display panel is tested through the 7-1 pad portion (242a3) and the 7-2 pad portion (242a4). That is, the test pattern may be a pattern for testing the performance of the display panel.

[0255] Referring to FIG. 19, the sizes of the 7-1 pad portion (242a3) and the 7-2 pad portion (242a4) are different from those of the 8-1 pad portion (242b1) and the 8-2 pad portion (242b2).

[0256] The 8-1 pad portion (242b1) and the 8-2 pad portion (242b2) are connected to the display panel. Therefore, the line width of the 8-1 pad portion (242b1) is equal to or similar to the line width of the 4th pad portion (222b). In addition, the line width of the 8-2 pad portion (242b2) is equal to or similar to the line width of the 6th pad portion (232b). Accordingly, when forming a circuit pattern and a test pattern, etching uniformity can be improved.

[0257] The line widths (W1a, W1b) of the 7-1 pad portion (242a3) and the 7-2 pad portion (242a4) are different from the line widths of the 8-1 pad portion (242b1) and the 8-2 pad portion (242b2). Specifically, the line widths (W1a, W1b) of the 7-1 pad portion (242a3) and the 7-2 pad portion (242a4) are larger than the line widths of the 8-1 pad portion (242b1) and the 8-2 pad portion (242b2).

[0258] The seventh pad portion (242a3, 242a4) requires a process of removing the first protective layer (310). If the size of the seventh pad portion (242a3, 242a4) is small, the first protective layer (310) must be removed finely. Accordingly, the process efficiency is reduced, and the first protective layer outside the seventh pad portion (242a3, 242a4) may be removed.

[0259] Additionally, if the size of the seventh pad portion (242a3, 242a4) is small, the contact area between the test device and the seventh pad portion (242a3, 242a4) decreases. Consequently, measurement errors in the test device may occur. This makes it difficult to measure the performance of the display panel.

[0260] Additionally, the line width (W1a, W1b) of the seventh pad portion (242a3, 242a4) may be larger than the line width (W3) of the third via. A first protective layer (310) and a second protective layer (320) are disposed on the third via (C3a, V3b). The protective layers on the third via (C3a, V3b) are not removed. Therefore, the size of the third via (C3a, V3b) is smaller than the size of the seventh pad portion (242a3, 242a4).

[0261] In addition, the line width (W1a, W1b) of the seventh pad portion (242a3, 242a4) may be larger than the spacing of at least one pad portion among the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), the fourth pad portion (222b), the fifth pad portion (232a), and the sixth pad portion (232b). For example, the line width (W1a, W1b) of the seventh pad portion (242a3, 242a4) may be larger than the spacing of each of the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), the fourth pad portion (222b), the fifth pad portion (232a), and the sixth pad portion (232b).

[0262] Additionally, the line width (W1a, W1b) of the seventh pad portion (242a3, 242a4) may be larger than the line width of at least one of the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), and the fourth pad portion (222b). In detail, the line width (W1a, W1b) of the seventh pad portion (242a3, 242a4) may be larger than the line widths of the first pad portion (212a), the second pad portion (212b), the third pad portion (222a), and the fourth pad portion (222b).

[0263] The shapes of the 7th pad portion (242a3, 242a4) and the 8th pad portion (242b1, 242b2) may be the same or different.

[0264] Referring to FIGS. 19 and 20, the seventh pad portions (242a3, 242a4) and the eighth pad portions (242b1, 242b2) have a rectangular shape. However, the embodiment is not limited thereto. The shapes of the seventh pad portions (242a3, 242a4) and the eighth pad portions (242b1, 242b2) may be different.

[0265] In FIGS. 17 to 20, two test patterns (240) facing each other in the second direction (2D) are illustrated. However, the implementation is not limited thereto. The test pattern (240) may include one test pattern (240). Alternatively, the test pattern (240) may include three or more test patterns (240).

[0266] The line width of the fourth wiring section (241) may be the same as or similar to the line width of at least one of the first wiring section (211), the second wiring section (221), and the third wiring section (231). Accordingly, when forming a circuit pattern and a test pattern, etching uniformity may be improved.

[0267] A flexible circuit board according to an embodiment includes a test pattern.

[0268] The flexible circuit board is connected to the display panel and the circuit board. The test pattern can measure the performance of the display panel. Therefore, the performance of the display panel can be verified before connecting the flexible circuit board and the display panel. This prevents COF module failure due to poor display panel performance after connecting the flexible circuit board, display panel, and circuit board.

[0269] The test pattern includes one pad portion connected to the display panel and another pad portion connected to the test device.

[0270] The line width of the other pad portion is larger than that of the first pad portion. The other pad portion is formed by removing the protective layer. Since the line width of the other pad portion is larger, the process of removing the protective layer becomes easier. This improves process efficiency. Furthermore, when removing the protective layer, other patterns can be prevented from being exposed outside the protective layer.

[0271] The test pattern is placed on the outermost side of the substrate. This prevents interference between the test pattern and the flexible circuit board when connecting the display panel.

[0272] Accordingly, the reliability and electrical characteristics of the flexible circuit board and COF module according to the embodiment are improved.

[0273]

[0274] 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).

[0275] Referring to FIG. 21, 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 according to the first embodiment, the display panel (4000) and the circuit board (3000) are placed on the same side of the COF module (2000).

[0276] Referring to FIG. 22, the display panel (4000) and the circuit board (3000) are placed on different sides 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 different sides of the COF module (2000).

[0277] Since the COF module (2000) includes a flexible substrate, it has a rigid shape and a bent shape between the display panel (3000) and the circuit board (4000). That is, the COF module (2000) may include a bending area (BA).

[0278] The COF module (2000) connects the display panel (4000) and the circuit board (3000), which are arranged opposite each other, in a curved shape. Consequently, the thickness of the electronic device is reduced. Furthermore, the design freedom of the electronic device is enhanced. Furthermore, the COF module (2000) prevents wires from breaking even when in a curved shape. Consequently, the reliability of the electronic device is enhanced.

[0279]

[0280] Because COF modules are flexible, they can be used in a variety of electronic devices.

[0281] For example, referring to FIG. 23, the COF module can be applied to a flexible touch window. Accordingly, a touch device device including the COF module can be a flexible touch device. Accordingly, the user can bend or fold it by hand. Such a flexible touch window can be applied to wearable touch devices, etc.

[0282] Referring to Fig. 24, the COF module can be applied to various wearable touch devices including curved displays. Accordingly, electronic devices including the COF module can be slimmed down or made lighter.

[0283] Referring to Fig. 25, the COF module can be used in various electronic devices having a display portion, such as a TV, monitor, or laptop. In this case, the COF module can also be used in an electronic device having a curved display portion.

[0284]

[0285] 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 just one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment can be combined or modified in other embodiments by those skilled in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be construed as falling within the scope of the present invention.

[0286] In addition, although the above description focuses on embodiments, these are merely examples and do not limit the present invention. Those skilled in the art to which the present invention pertains will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present embodiments. For example, each component specifically shown in the embodiments can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention defined in the appended claims.

Claims

1. A substrate comprising a first side and a second side opposite to the first side; a circuit pattern arranged on the first surface; and A protective layer disposed on the circuit pattern and including a plurality of open areas, The above description includes a first side end and a second side end facing each other in the first direction, The open area includes a first open area provided between the first side end and the second side end, a second open area spaced apart from the first open area and closer to the first side end, and a third open area spaced apart from the first open area and closer to the second side end. The above circuit pattern is, A first circuit pattern including a first pad portion arranged in the first open area; a second pad portion arranged in the second open area; and a first wiring portion connecting the first pad portion and the second pad portion, and A second circuit pattern including a third pad portion arranged in the first open area; a fourth pad portion arranged in the third open area; and a second wiring portion connecting the third pad portion and the fourth pad portion, The first direction in which the second pad portion and the fourth pad portion face each other, the second direction perpendicular to the first direction, and the third direction between the first direction and the second direction are defined, A flexible circuit board having at least one fourth pad portion extending in the third direction on the substrate.

2. In paragraph 1, The fourth pad portion is a flexible circuit board extending in the first direction and the third direction.

3. In paragraph 2, The above fourth pad portion includes a central pad portion and an outer pad portion, The above central pad portion extends in the first direction, The above outer pad portion is a flexible circuit board extending in the third direction.

4. In paragraph 3, A flexible circuit board in which the angle of inclination of the outer pad portion increases as it moves away from the central pad portion.

5. In paragraph 3, The above second wiring section includes a 2-1 wiring section and a 2-2 wiring section, The above 2-1 wiring section extends in the first direction, The above 2-2 wiring section extends in the first direction and the third direction, A flexible circuit board in which the maximum inclination angle of the outer pad portion is smaller than the maximum inclination angle of the 2-2 wiring portion.

6. In paragraph 3, A flexible circuit board in which the outer pad portion extends in a different direction from at least one of the first pad portion, the second pad portion, and the third pad portion.

7. In paragraph 1, A flexible circuit board, wherein the circuit pattern further includes a third circuit pattern including a fifth pad portion arranged in the second open area; a sixth pad portion arranged in the third open area; and a third wiring portion connecting between the fifth pad portion and the sixth pad portion.

8. In paragraph 7, A flexible circuit board having at least one sixth pad portion extending in the third direction.

9. In paragraph 8, The above sixth pad portion is a flexible circuit board extending in the first direction and the third direction.

10. In paragraph 8, The above sixth pad portion includes a central pad portion and an outer pad portion, The above central pad portion extends in the first direction, The above outer pad portion is a flexible circuit board extending in the third direction.

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