Flexible printed circuit board, cof module, and electronic device including the same

Abstract

A flexible printed circuit board of an embodiment includes a substrate, a circuit pattern disposed on the substrate, and a protective layer disposed on the circuit pattern, the circuit pattern including a first circuit pattern and a second circuit pattern, the first circuit pattern including a first land portion, a second land portion, and a first wiring portion connected to the first land portion and the second land portion, the first wiring portion including a first pattern extending in contact with the second land portion, the first pattern including a first pattern portion and a second pattern portion disposed under the protective layer, the first pattern portion including an extension region having a width greater than a width of the second pattern portion, and a maximum width of the first pattern portion being greater than a maximum width of the second land portion.

Description

TECHNICAL FIELD

[0001] Embodiments relate to a flexible printed circuit board, a COF module including the same, and an electronic device including the same. Particularly, the flexible printed circuit board can be a flexible printed circuit board for a COF. BACKGROUND

[0002] Recently, various electronic devices are slimmed, miniaturized, and lightened. Accordingly, various researches are being conducted on mounting semiconductor chips in a narrow area of an electronic device in a high density.

[0003] Among them, a chip on film (COF) method is used for a flexible substrate, and thus, the COF method can be applied to both a flat panel display and a flexible display. That is, the COF method can be applied to various wearable electronic devices, and thus, the COF method is being spotlighted. In addition, the COF method can achieve a small pitch, and thus, the COF method can be used to implement a high resolution display (QHD) based on an increase in the number of pixels.

[0004] A chip on film (COF) is a method of mounting a semiconductor chip in a film form on a flexible printed circuit board. For example, the semiconductor chip can be an integrated circuit (IC) chip or a large scale integrated circuit (LSI) chip.

[0005] On the other hand, the chip can be connected with an external PCB and a display panel through a circuit pattern. For example, one end portion and the other end portion of the circuit pattern are respectively provided with a pad portion. One pad portion can be electrically connected with a terminal of the chip, and the other pad portion can be connected with a terminal of the PCB and the display panel.

[0006] Accordingly, the chip, the PCB, and the display panel can be electrically connected through the COF, and a signal can be transmitted to the display panel through the circuit pattern.

[0007] As described above, a flexible printed circuit board of a chip on film (COF) type is applied to a flexible display. Accordingly, the flexible printed circuit board can be bent in one direction.

[0008] Accordingly, when the flexible printed circuit board is bent, a crack or a delamination can occur in the circuit pattern located in a bending area. Accordingly, an electrical characteristic of the flexible printed circuit board can be deteriorated.

[0009] At this time, in order to electrically connect the pattern portion and the electrode, the partition wall portion must have a prescribed dielectric characteristic. However, a problem is that, due to such a dielectric characteristic, a leakage current increases in a direction of the partition wall portion between the pattern portions, and thus, a driving voltage increases and a driving characteristic deteriorates.

[0010] Accordingly, there is a need for a flexible printed circuit board having a novel structure capable of solving the above-described problems. Summary of the Invention

[0011] Technical issues

[0012] The embodiment provides a flexible printed circuit board that can improve the reliability of the circuit pattern of the flexible printed circuit board when it is bent.

[0013] Technical solution

[0014] The flexible printed circuit board of the embodiment includes a substrate, a circuit pattern disposed on the substrate, and a protective layer disposed on the circuit pattern. The circuit pattern includes a first circuit pattern and a second circuit pattern. The first circuit pattern includes a first pad portion, a second pad portion, and a first wiring portion connected to the first pad portion and the second pad portion. The first wiring portion includes a first pattern extending in contact with the second pad portion. The first pattern includes a first pattern portion and a second pattern portion disposed under the protective layer. The first pattern portion includes an extension region with a width greater than the width of the second pattern portion. The maximum width of the first pattern portion is greater than the maximum width of the second pad portion.

[0015] Beneficial effects

[0016] The flexible printed circuit board of the embodiment includes a first wiring portion and a second wiring portion. The width or thickness of the first wiring portion disposed in the first region may be greater than the width or thickness of the first wiring portion disposed in the second region. Therefore, the strength of the first wiring portion in the first region can be increased. Therefore, it is possible to prevent cracks from forming in the first wiring portion disposed in the first region when the flexible printed circuit board is bent or folded in the first region.

[0017] Furthermore, the width of the first wiring portion disposed in the first region can be changed. That is, the width of the first wiring portion disposed in the first region can gradually decrease as it moves away from the bending axis. Alternatively, the width of the first wiring portion disposed in the first region can gradually increase as it moves away from the bending axis.

[0018] Therefore, the width of the first wiring section can be set according to the stress change corresponding to the shape of the first area bent by means of the bending shaft. Attached Figure Description

[0019] Figure 1 This is a top view of the flexible printed circuit board of an embodiment.

[0020] Figure 2 This is a top view of the flexible printed circuit board in the first embodiment, with the circuit pattern omitted.

[0021] Figure 3 and Figure 4 Therefore Figure 1The sectional view is taken by the section line A-A' in the diagram.

[0022] Figure 5 Therefore Figure 1 The sectional view is taken by the section line B-B' in the diagram.

[0023] Figures 6 to 11 yes Figure 1 A magnified view of region C in the image.

[0024] Figure 12 Therefore Figure 11 The sectional view is taken by the cutting line D-D' in the diagram.

[0025] Figure 13 This is a top view of the COF module in the embodiment.

[0026] Figure 14 This is a cross-sectional view showing the connection relationships of the COF module, including the flexible printed circuit board of the embodiment.

[0027] Figures 15 to 17 This is a diagram of an electronic device including a flexible printed circuit board according to an embodiment. Detailed Implementation

[0028] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the spirit and scope of the present disclosure are not limited to the partial embodiments described, but can be implemented in many other forms, and one or more constituent elements in the embodiments may be selectively combined and substituted within the spirit and scope of the present disclosure.

[0029] Furthermore, unless otherwise explicitly defined and described, the terms (including technical and scientific terms) used in the embodiments of this disclosure are to be interpreted as having the meaning commonly understood by one of ordinary skill in the art to which this invention pertains, and the meanings of terms as defined in commonly used dictionaries are to be interpreted as having the meanings consistent with their meanings in the relevant field context.

[0030] Furthermore, the terminology used in the embodiments of this disclosure is for the purpose of describing the embodiments and is not intended to limit the disclosure. In this specification, unless expressly stated herein, the singular form may also include the plural form, and when described as “at least one of A (and), B, and C”, it may include at least one of all combinations that can be composed of A, B, and C.

[0031] Furthermore, in describing the constituent elements of the embodiments of this disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are used only to distinguish the constituent element from other constituent elements, and these terms do not limit the nature, order, or sequence of the constituent elements.

[0032] In addition, when a constituent element is described as being "connected", "combined", or "in contact" with other constituent elements, it can include not only situations where the constituent element is directly "connected", "combined", or "in contact" with other constituent elements, but also situations where the constituent element is "connected", "combined", or "in contact" with other constituent elements through another constituent element between the constituent element and other constituent elements.

[0033] Furthermore, when described as being formed on or configured on the “above” or “below” of the constituent elements, “above” or “below” may include not only the case where two constituent elements are directly connected to each other, but also the case where one or more other constituent elements are formed on or configured between the two constituent elements.

[0034] Additionally, when expressed as "above" or "below", based on a constituent element, it can include not only the upper direction but also the lower direction.

[0035] Hereinafter, a flexible printed circuit board, a COF module, and an electronic device including the thereof will be described with reference to the accompanying drawings.

[0036] Figure 1 and Figure 2 This is a top view of the flexible printed circuit board of an embodiment.

[0037] Reference Figure 1 and Figure 2 The flexible printed circuit board 1000 of the embodiment may include a substrate 100 and a circuit pattern 200 disposed on the substrate 100.

[0038] Substrate 100 may include a flexible substrate. For example, substrate 100 may be a polyimide (PI) substrate. However, embodiments are not limited thereto, and substrate 100 may comprise polymer materials such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). Therefore, flexible printed circuit boards including substrate 100 can be used in various electronic devices with curved display devices. For example, flexible printed circuit boards including substrate 100 have excellent flexibility properties and are therefore suitable for mounting semiconductor chips on wearable electronic devices.

[0039] The thickness of substrate 100 can be from 20 μm to 100 μm. For example, the thickness of substrate 100 can be from 25 μm to 50 μm. For example, the thickness of substrate 100 can be from 30 μm to 40 μm. When the thickness of substrate 100 is greater than 100 μm, the total thickness of the flexible printed circuit board increases, thus leading to a deterioration in flexibility. Furthermore, when the thickness of substrate 100 is less than 20 μm, the flexible printed circuit board may be damaged by the heat / pressure applied to it when chips are mounted on it.

[0040] The substrate 100 may include an effective region AA and an ineffective region UA. For example, the effective region AA may be the central region of the substrate 100, and the ineffective region UA ​​may be the edge region of the substrate 100.

[0041] The effective area AA may include the chip mounting area CA. Specifically, the effective area AA may include the chip mounting area CA for mounting a chip C connected to the circuit pattern.

[0042] Additionally, circuit patterns 210 and 220 can be configured within the effective area AA. Specifically, multiple circuit patterns spaced apart from each other and extending in multiple directions can be configured within the effective area AA.

[0043] The effective area AA can be the area actually used in the flexible printed circuit board 1000. That is, the effective area AA can be the area connected to the display panel or the printed circuit board.

[0044] Circuit patterns may not be placed in the invalid region UA. That is, the valid region AA and the invalid region UA ​​can be divided based on whether or not a circuit pattern is arranged there.

[0045] The invalid region UA ​​may include multiple holes. Specifically, the invalid region UA ​​may include multiple perforations H. The flexible printed circuit board can be wound or unwound in a roll-to-roll manner through the perforations H.

[0046] The invalid region UA ​​can be an area in the flexible printed circuit board 1000 that is not actually used. That is, the invalid region UA ​​is an area that can be removed.

[0047] The boundary between the valid region AA and the invalid region can be defined as the cutting line CL.

[0048] Specifically, a COF module can be formed by mounting a chip on a flexible printed circuit board 1000 and cutting cleaving lines CL. Furthermore, COF modules can be configured in a variety of electronic devices.

[0049] Reference Figure 1 and Figure 2 A bending axis BAX can be defined in the flexible printed circuit board 1000. Specifically, the flexible printed circuit board 1000 can be bent in one direction. Therefore, the flexible printed circuit board 1000 can define a bending axis BAX formed along the bending direction.

[0050] Furthermore, in the flexible printed circuit board 1000, a first region 1A and a second region 2A can be defined by a bending axis BAX. That is, the flexible printed circuit board 1000 may include regions with curvature and regions with (almost) no curvature. For example, the flexible printed circuit board 1000 may include a first region 1A with a curvature R greater than zero and a second region 2A with a curvature equal to or close to zero. The first region 1A may be a region that is bent when the flexible printed circuit board 1000 is bent, and the second region 2A may be a region that is not bent when the flexible printed circuit board 1000 is bent. The second region may be a flat or nearly flat region.

[0051] The curvature R can be defined as the reciprocal of the radius of curvature.

[0052] The circuit pattern may include wiring portions and pad portions. Furthermore, multiple circuit patterns may be configured in the effective area AA. Specifically, a first circuit pattern 210 and a second circuit pattern 220 may be configured in the effective area AA.

[0053] Reference Figure 1 , Figure 3 as well as Figure 4 The first circuit pattern 210 may include a first wiring portion 211, a first pad portion 212a, and a second pad portion 212b. Specifically, the first circuit pattern 210 may include a first pad portion 212a disposed inside the chip mounting region CA. Additionally, the first circuit pattern 210 may include a second pad portion 212b disposed outside the chip mounting region CA. Furthermore, the first wiring portion 211 may connect to the first pad portion 212a and the second pad portion 212b.

[0054] The first wiring section 211, the first pad section 212a, and the second pad section 212b can be formed as one unit.

[0055] In addition, the first wiring portion 211 can be configured to extend in the A1 direction relative to the chip mounting area CA.

[0056] The first pad portion 212a can be electrically connected to a chip disposed in the chip mounting area. Additionally, the second pad portion 212b can be electrically connected to a display panel. Furthermore, the first wiring portion 211 can transmit signals between the chip and the display panel.

[0057] A protective layer 300 may be disposed on the first circuit pattern 210. Specifically, the protective layer 300 may be disposed on the first wiring portion 211. The protective layer 300 may be configured to surround the first wiring portion 211. Alternatively, the protective layer 300 may not be disposed on the first pad portion 212a and the second pad portion 212b.

[0058] That is, the first wiring portion 211 is disposed under the protective layer 300. In addition, the protective layer 300 is not disposed on the first pad portion 212a and the second pad portion 212b, and they are exposed to the outside of the protective layer.

[0059] Reference Figure 1 and Figure 5 The second circuit pattern 220 may include a second wiring portion 221, a third pad portion 222a, and a fourth pad portion 222b. Specifically, the second circuit pattern 220 may include a third pad portion 222a disposed inside the chip mounting region CA. Additionally, the second circuit pattern 220 may include a fourth pad portion 222b disposed outside the chip mounting region CA. Furthermore, the second wiring portion 221 may connect to the third pad portion 222a and the fourth pad portion 222b.

[0060] The second wiring section 221, the third pad section 222a, and the fourth pad section 222b can be formed as one unit.

[0061] Furthermore, the second wiring portion 221 can be configured to extend in the A2 direction relative to the chip mounting region CA. Specifically, the second wiring portion 221 can be configured to extend in the A2 direction, which is opposite to the A1 direction.

[0062] The third pad portion 222a can be electrically connected to a chip disposed in the chip mounting area. Additionally, the fourth pad portion 222b can be electrically connected to the display panel. Furthermore, the second wiring portion 221 can transmit signals between the chip and the display panel.

[0063] The protective layer 300 may be disposed on the second circuit pattern 220. Specifically, the protective layer 300 may be disposed on the second wiring portion 221. The protective layer 300 may be configured to surround the second wiring portion 221. Alternatively, the protective layer 300 may not be disposed on the third pad portion 222a and the fourth pad portion 222b.

[0064] That is, the second wiring portion 221 is disposed under the protective layer 300. In addition, the protective layer 300 is not disposed on the third pad portion 222a and the fourth pad portion 222b, and they are exposed to the outside of the protective layer.

[0065] The first circuit pattern 210 and the second circuit pattern 220 may comprise a metallic material with excellent electrical conductivity. Specifically, the first circuit pattern 210 and the second circuit pattern 220 may comprise copper (Cu). However, the embodiments are not limited thereto, and the first circuit pattern 210 and the second circuit pattern 220 may comprise at least one metal selected from copper (Cu), aluminum (Al), chromium (Cr), nickel (Ni), silver (Ag), molybdenum (Mo), gold (Au), titanium (Ti), and alloys thereof.

[0066] The following will refer to Figure 3 and Figure 4 The layer structure of the circuit pattern of the flexible printed circuit board of the embodiment is described. Figure 3 and Figure 4 The first circuit pattern 210 will be described primarily here. However, the embodiments are not limited thereto. Figure 3 and Figure 4 The description of the layer structure described herein can also be applied to the second circuit pattern 220.

[0067] Reference Figure 3 The first circuit pattern 210 can be formed in multiple layers. Specifically, the first wiring portion 211 and the first pad portion 212a may include a first metal layer 201 and a second metal layer 202. Additionally, although not shown... Figure 3 However, the second pad portion 212b may also include a first metal layer 201 and a second metal layer 202.

[0068] The first metal layer may be a seed layer of the first circuit pattern 210. Specifically, the first metal layer 201 may be a seed layer disposed on the substrate 100 by electroless plating of a metal material such as copper (Cu).

[0069] Alternatively, the second metal layer 202 can be a plating layer. Specifically, the second metal layer 202 can be a plating layer formed by electroplating using the first metal layer 201 as a seed layer.

[0070] The thickness of the first metal layer 201 may be less than the thickness of the second metal layer 202.

[0071] For example, the thickness of the first metal layer 201 can be 0.7 μm to 2 μm, and the thickness of the second metal layer 202 can be 10 μm to 25 μm.

[0072] The first metal layer 201 and the second metal layer 202 may contain the same metallic material. For example, the first metal layer 201 and the second metal layer 202 may contain copper (Cu).

[0073] Additionally, a bonding layer 203 may be disposed on the second metal layer 202. Specifically, the bonding layer 203 may be disposed on the side surface of the first metal layer 201, the side surface of the second metal layer 202, and the upper surface of the second metal layer 202. That is, the bonding layer 203 may be configured to surround the first metal layer 201 and the second metal layer 202.

[0074] The bonding layer 203 may contain metal. Specifically, the bonding layer 203 may contain tin (Sn).

[0075] The bonding layer 203 can be formed with a thickness of 0.3 μm to 0.7 μm. As it extends from the lower surface in contact with the second metal layer 202 to the upper surface, the bonding layer 203 can have a higher tin content.

[0076] That is, the bonding layer 203 is configured to contact the second metal layer 202. Therefore, in the direction from the lower surface to the upper surface, the tin content of the bonding layer 203 increases and the copper content decreases.

[0077] Therefore, only pure tin remains on the upper surface of the bonding layer 203 with a thickness ranging from 0.1 μm to 0.3 μm.

[0078] Through the bonding layer 203, the terminals of the chip, printed circuit board, and display panel can be easily bonded to the first and second pad portions by heat and pressure. That is, when heat and pressure are applied to the first and second pad portions, the upper surface of the bonding layer containing pure tin melts. Therefore, the first and second pad portions can be easily bonded to the terminals of the chip, printed circuit board, and display panel.

[0079] Therefore, the bonding layer 203 is not separated from the first pad portion 212a and can become part of the first pad portion.

[0080] The first circuit pattern 210 may be configured to have a thickness of 2 μm to 25 μm. For example, the first circuit pattern 210 may be configured to have a thickness of 5 μm to 20 μm. For example, the first circuit pattern 210 may be configured to have a thickness of 7 μm to 15 μm.

[0081] The first circuit pattern 210 undergoes a process of etching the first metal layer by flash etching, which is performed to separate the circuit pattern, during the manufacturing process. Therefore, the final manufactured first circuit pattern 210 can be less than the sum of the thicknesses of the first metal layer 201, the second metal layer 202, and the bonding layer 203.

[0082] When the thickness of the first circuit pattern 210 and the second circuit pattern 220 is less than 2 μm, the resistance of the first circuit pattern 210 and the second circuit pattern 220 will increase. When the thickness of the first circuit pattern 210 and the second circuit pattern 220 is greater than 25 μm, it will be difficult to achieve fine patterns.

[0083] On the other hand, a buffer layer may be further disposed between the substrate 100 and the first circuit pattern 210 and the second circuit pattern 220. The buffer layer can improve the adhesion between the substrate 100, which is a heterogeneous material, and the first circuit pattern 210 and the second circuit pattern 220.

[0084] The buffer layer 205 can be formed in multiple layers. Specifically, a first buffer layer 205a and a second buffer layer 205b located on the first buffer layer 205a can be disposed on the substrate 100. Therefore, the first buffer layer 205a can contact the substrate 100, and the second buffer layer 205b can be configured to contact the first circuit pattern 210.

[0085] The first buffer layer 205a may contain a material that adheres well to the substrate 100. For example, the first buffer layer 205a may contain nickel (Ni). Additionally, the second buffer layer 205b may contain a material that adheres well to the first circuit pattern 210. For example, the second buffer layer 205b may contain chromium (Cr).

[0086] The buffer layer, including the first buffer layer 205a and the second buffer layer 205b, can have a nanometer-scale film thickness. For example, the thickness of the buffer layer 205 can be less than 20 nm.

[0087] The adhesion between the substrate 100, which is a heterogeneous material, and the first circuit pattern 210 can be improved by the buffer layer 205, thereby preventing the first circuit pattern 210 from delaminating.

[0088] On the other hand, refer to Figure 4 The bonding layer 203 may include a first bonding layer 203a and a second bonding layer 203b.

[0089] Specifically, the first bonding layer 203a may be disposed on the first wiring portion 211 and the first pad portion 212a. Additionally, although not shown in the drawings, the first bonding layer 203a may also be disposed on the second pad portion 212b. That is, the first bonding layer 203a may be disposed on the first circuit pattern 210.

[0090] Furthermore, the second bonding layer 203b may be disposed only on the first pad portion 212a and the second pad portion 212b. That is, the first wiring portion 211 has a different layer structure from the first pad portion 212a and the second pad portion 212b due to the second bonding layer 203b.

[0091] The first bonding layer 203a and the second bonding layer 203b may contain metal. Specifically, the first bonding layer 203a and the second bonding layer 203b may contain tin (Sn).

[0092] The first bonding layer 203a and the second bonding layer 203b may be configured to have different thicknesses. Specifically, the thickness of the second bonding layer 203b may be greater than the thickness of the first bonding layer 203a.

[0093] For example, the first bonding layer 203a may have a film thickness of 0.02 μm to 0.06 μm, and the second bonding layer 203b may have a thickness of 0.2 μm to 0.6 μm.

[0094] When the bonding layer between the protective layer 300 and the first wiring portion 211 is configured to be thick, cracks will occur when the flexible printed circuit board is bent. Therefore, the first bonding layer 203a between the protective layer 300 and the first wiring portion 211 can be formed to have a thin film thickness. Thus, it is possible to prevent cracks from occurring when the flexible printed circuit board is bent.

[0095] In addition, as the second bonding layer 203b extends from the lower surface in contact with the first bonding layer 203a to the upper surface, it can have a higher tin content.

[0096] That is, in the second bonding layer 203b, from the lower surface to the upper surface, the tin content increases and the copper content decreases.

[0097] Therefore, only pure tin remains on the upper surface of the second bonding layer 203b with a thickness ranging from 0.1 μm to 0.3 μm.

[0098] Through the second bonding layer 203b, the terminals of the chip, printed circuit board, and display panel can be easily bonded to the first and second pad portions by heat and pressure. Specifically, when heat and pressure are applied to the first and second pad portions, the upper surface of the bonding layer containing pure tin melts. Therefore, the first and second pad portions can be easily bonded to the terminals of the chip, printed circuit board, and display panel.

[0099] Therefore, the first bonding layer 203a and the second bonding layer 203b are not separated from the first pad portion 212a, but can become part of the first pad portion.

[0100] On the other hand, the protective layer 300 may be disposed on the wiring portions of the first circuit pattern 210 and the second circuit pattern 220. Specifically, the protective layer 300 may be configured to surround the first wiring portion 211 and the second wiring portion 221. That is, the protective layer 300 may be disposed on the first circuit pattern 210 and the second circuit pattern 220 except for the first pad portion, the second pad portion, the third pad portion, and the fourth pad portion.

[0101] The protective layer 300 may contain solder paste. For example, the protective layer 300 may contain solder paste containing a thermosetting resin, a thermoplastic resin, a filler, a curing agent, or a curing accelerator.

[0102] As described above, a flexible printed circuit board (PCB) can be bent in one direction. Therefore, a bending region can be formed in the PCB. In the bending region, compressive and tensile stresses may be generated due to bending. Consequently, the circuit pattern disposed in the bending region of the PCB may crack or detach from the substrate due to compressive and tensile stresses.

[0103] The following describes a flexible printed circuit board with a novel structure that can solve the problems mentioned above.

[0104] First, refer to Figure 1 and Figure 2 As described above, the flexible printed circuit board 1000 includes a bending axis BAX. Furthermore, in the flexible printed circuit board 1000, a first region 1A and a second region 2A can be defined based on the bending axis BAX.

[0105] The bending axis BAX can be configured to be adjacent to the second pad portion 212b. Specifically, the bending axis BAX can be configured to be closer to the second pad portion 212b than the fourth pad portion 222b. Therefore, the first region 1A formed based on the bending axis BAX can be configured to be adjacent to the second pad portion 212b of the first circuit pattern 210. That is, the bending axis BAX can be configured to be closer to the second pad portion 212b of the first circuit pattern than the fourth pad portion 222b of the second circuit pattern.

[0106] Additionally, the first region 1A may be configured to be spaced apart from the ends of the protective layer 300. For example, the protective layer 300 may include a first end E1, a second end E2, a third end E3, and a fourth end E4. The first end E1 may be configured to be adjacent to the second pad portion 212b, and the second end E2 may be configured to be adjacent to the fourth pad portion 222b. The first end E1 and the second end E2 may extend in one direction opposite to each other.

[0107] Additionally, the third end E3 and the fourth end E4 can be configured to connect the first end E1 and the second end E2. The third end E3 and the fourth end E4 can extend opposite each other in a direction different from the one described above.

[0108] The first region 1A can be separated from the end of the protective layer 300 within a set range. Specifically, the first region 1A can be configured to be separated from the first end E1 by less than 5 mm. More specifically, the first region 1A can be configured to be separated from the first end E1 by less than 1 mm.

[0109] The first region 1A can be defined (limited) by a first boundary region BA1 and a second boundary region BA2 of the substrate 100. The first boundary region BA1 is defined as the boundary region between the first region 1A and the 2-1 region 2-1A on which the second pad portion 212b is disposed. In addition, the second boundary region BA2 is defined as the boundary region between the first region 1A and the 2-2 region 2-2A on which the fourth pad portion 222b is disposed.

[0110] For example, the first boundary region BA1 can be defined as the region where bending begins in the flexible printed circuit board, and the second boundary region BA2 can be defined as the region where bending ends in the flexible printed circuit board.

[0111] Therefore, the first region 1A can be configured between the first boundary region BA1 and the second boundary region BA2.

[0112] The circuit pattern can be configured in both the first region 1A and the second region 2A. Specifically, the first wiring portion 211 can be configured in both the first region 1A and the second region 2A simultaneously. Furthermore, the widths of the first wiring portions 211 configured in the first region 1A and the second region 2A can be different. Additionally, the spacing between the first wiring portions 211 configured in the first region 1A and the second region 2A can be different.

[0113] Figures 6 to 11 yes Figure 1 A magnified view of region C in the image.

[0114] Reference Figure 6 The first circuit pattern 210 can be formed with different widths and spacings in each region. Specifically, the first wiring portion 211 of the first circuit pattern 210 can be formed with different widths and spacings in each region.

[0115] Specifically, the first wiring portion 211 may include a first pattern P1 and a second pattern P2. The first pattern P1 and the second pattern P2 may be connected to each other. That is, the first pattern P1 and the second pattern P2 may be formed as a single unit. In addition, the first pattern P1 and the second pattern P2 may extend in different directions. Specifically, the second pattern P2 may be bent and extended from the first pattern P1.

[0116] The first pattern P1 can be connected to the second pad portion 212b connected to the display panel. Specifically, the first pattern P1 can contact the second pad portion 212b and extend in the direction of the second pad portion 212b. More specifically, the first pattern P1 can contact the second pad portion 212b and extend linearly in the direction of the second pad portion 212b.

[0117] Additionally, the second pattern P2 can be connected to the first pad portion 212a connected to the chip. That is, the first pad portion 212a and the second pad portion 212b can be connected via the first pattern P1 and the second pattern P2.

[0118] In the accompanying drawings, for ease of description, a second pattern P2 is shown extending in one direction as a bend from the first pattern P1, but the embodiment is not limited thereto. The second pattern P2 may be connected to the first pattern P1 and connected to the first pad portion 212a extending in multiple directions. That is, the second pattern P2 connected to the first pattern P1 may be configured to extend in at least one direction.

[0119] The protective layer 300 can be disposed on the first pattern P1. Additionally, the protective layer 300 can be disposed on the second pattern P2. That is, the first pattern P1 and the second pattern P2 can be disposed under the protective layer 300. Therefore, deformation of the wiring section due to external impurities can be prevented.

[0120] The first pattern P1 may include an extension region P. Specifically, the first pattern P1 may include a first pattern portion PA1 and a second pattern portion PA2. The widths and spacings of the first pattern portion PA1 and the second pattern portion PA2 may be different from each other. For example, the width of the first pattern portion PA1 may be greater than the width of the second pattern portion PA2, and the spacing between the first pattern portions PA1 may be smaller than the spacing between the second pattern portions PA2. That is, the first pattern portion PA1 may be an extension region P of the first pattern P1. More specifically, the first pattern portion PA1 may include an extension region P with a width greater than the width of the second pattern portion PA2.

[0121] Specifically, the first pattern P1 can be configured in the first region 1A and the second region 2A. In addition, the second pattern P2 can be configured in the second region 2A.

[0122] That is, the first pattern P1 may include a first pattern portion PA1 and a second pattern portion PA2 disposed in the first region 1A and the second region 2A. Specifically, the first pattern P1 may include a first pattern portion PA1 disposed in the first region 1A and a second pattern portion PA2 disposed in the second region 2A. More specifically, the first pattern P1 may include a first pattern portion PA1 disposed in the bent region of the flexible printed circuit board 1000 and a second pattern portion PA2 disposed in the unbent region of the flexible printed circuit board 1000. More specifically, the first pattern P1 may include a first pattern portion PA1 disposed in the bent region of the flexible printed circuit board 1000 and a second pattern portion PA2 disposed in the unbent region of the flexible printed circuit board 1000.

[0123] Therefore, the width of the first pattern portion PA1 disposed in the first region 1A can be greater than the width of the second pattern portion PA2 disposed in the second region 2A, and the spacing can be smaller.

[0124] At this time, the first patterned portion PA1 can be configured to be spaced apart from the end of the protective layer 300. Specifically, the first patterned portion PA1 can be configured to be spaced apart from the end of the protective layer 300 within a set range. Specifically, the first patterned portion PA1 can be configured to be spaced apart from the first end E1 by 5 mm or less. More specifically, the first patterned portion PA1 can be configured to be spaced apart from the first end E1 by 1 mm or less. That is, the first patterned portion PA1 can be configured within 5 mm or 1 mm from the first end E1.

[0125] That is, the extended area of ​​the first pattern can be configured within 15 mm or 1 mm from the first end of the protective layer 300.

[0126] The maximum width of the first pattern portion PA1 can be greater than the maximum width of the other pattern portions. Specifically, the maximum width of the first pattern portion PA1 can be greater than the maximum width of the second pad portion 212b.

[0127] Additionally, refer to Figure 6 The width and spacing of the first pattern portion PA1 disposed in the first region 1A may differ from the width and spacing of the second pattern portion PA2 disposed in the second region 2A. For example, the first pattern portion PA1 may be formed to have a first width W1 in the first region 1A and may be spaced apart from each other by a first spacing S1. In addition, the second pattern portion PA2 may be formed to have a second width W2 in the second region 2A and may be spaced apart from each other by a second spacing S2.

[0128] At this point, the size of the first width W1 and the size of the second width W2 can be different. Specifically, the size of the first width W1 can be larger than the size of the second width W2. Furthermore, the size of the first interval S1 and the size of the second interval S2 can be different. Specifically, the size of the first interval S1 can be smaller than the size of the second interval S2.

[0129] That is, the width of the first pattern part PA1 disposed in the first region 1A is greater than the width of the second pattern part PA2 disposed in the second region 2A, and the interval between the first pattern parts PA1 disposed in the first region 1A may be smaller than the interval between the second pattern parts PA2 disposed in the second region 2A.

[0130] Specifically, the extension region P of the first pattern portion PA1 may include a protrusion extending in the width direction of the first wiring portion. Therefore, the width of the first pattern portion PA1 disposed in the first region 1A is greater than the width of the protrusion than the width of the second pattern portion PA2 disposed in the second region 2A. In addition, the spacing between the first pattern portions PA1 disposed in the first region 1A is smaller than the spacing between the second pattern portions PA2 disposed in the second region 2A than the width of the protrusion.

[0131] At this point, the protrusion can be formed with a width within a predetermined range. Specifically, the width W3 of the protrusion can be less than the second interval S2. More specifically, the width W3 of the protrusion can be less than 50% of the second interval S2. That is, the width W3 of the protrusion can be less than or equal to half of the second interval S2. The second interval S2 can be defined as the smallest interval among the intervals of the second interval S2. When the width W3 of the protrusion is greater than 50% of the second interval S2, a short circuit may occur in the first pattern portions PA1 adjacent to each other in the first region 1A. Therefore, the reliability of the flexible printed circuit board will be reduced.

[0132] In the flexible printed circuit board of the embodiment, such as Figure 6As shown, the width of the first pattern portion disposed in the first region can be greater than the width of the second pattern portion disposed in the second region. Therefore, the strength of the first wiring portion disposed in the first region can be improved. Thus, it is possible to prevent cracks from forming in the first wiring portion disposed in the bending region when the flexible printed circuit board is bent.

[0133] Reference Figure 7 and Figure 8 The first wiring portion 211 of the first circuit pattern 210 in each region can be formed to have different widths and spacings.

[0134] Specifically, the width and spacing of the first pattern portion PA1 disposed in the first region 1A may differ from the width and spacing of the second pattern portion PA2 disposed in the second region 2A. For example, the first pattern portion PA1 may be formed to have a first width W1 in the first region 1A and may be spaced apart from each other by a first spacing S1. In addition, the second pattern portion PA2 may be formed to have a second width W2 in the second region 2A and may be spaced apart from each other by a second spacing S2.

[0135] At this point, the size of the first width W1 and the size of the second width W2 can be different. Specifically, the size of the first width W1 can be larger than the size of the second width W2. Additionally, the size of the first interval S1 and the size of the second interval S2 can be different. Specifically, the size of the first interval S1 can be smaller than the size of the second interval S2.

[0136] Furthermore, the distance between the first wiring portions 211 can vary in the first region 1A. Specifically, the first interval S1 of the first pattern portion PA1 can vary as it extends from the first boundary region BA1 to the second boundary region BA2.

[0137] Reference Figure 7 As the distance extends from the first boundary region BA1 toward the bending axis BAX, the first interval S1 can decrease. That is, the first interval S1 at the first boundary region BA1 can be greater than the first interval S1 at the bending axis BAX.

[0138] Furthermore, as it extends from the second boundary region BA2 towards the bending axis BAX, the first interval S1 can decrease. That is, the first interval S1 at the second boundary region BA2 can be greater than the first interval S1 at the bending axis BAX.

[0139] Therefore, the width of the first pattern portion PA1 in the first region 1A can also vary. That is, the first width W1 of the first pattern portion PA1 in the first region 1A can be the largest at the bending axis BAX and the smallest at the first boundary region BA1 and the second boundary region BA2. For example, the first width W1 of the first pattern portion PA1 in the first region 1A can gradually decrease as it extends from the bending axis BAX towards the first boundary region BA1. In addition, the first width W1 of the first pattern portion PA1 in the first region 1A can gradually decrease as it extends from the bending axis BAX towards the second boundary region BA2.

[0140] Or, refer to Figure 8 As the distance extends from the first boundary region BA1 toward the bending axis BAX, the first interval S1 can increase. That is, the first interval S1 at the first boundary region BA1 can be smaller than the first interval S1 at the bending axis BAX.

[0141] Furthermore, as it extends from the second boundary region BA2 towards the bending axis BAX, the first interval S1 can decrease. That is, the first interval S1 at the second boundary region BA2 can be smaller than the first interval S1 at the bending axis BAX.

[0142] Therefore, the width of the first pattern portion PA1 in the first region 1A can also vary. That is, the first width W1 of the first pattern portion PA1 in the first region 1A can be minimum at the bending axis BAX, and maximum at the first boundary region BA1 and the second boundary region BA2. For example, the first width W1 of the first pattern portion PA1 in the first region 1A can gradually increase as it extends from the bending axis BAX towards the first boundary region BA1, and can also gradually increase as it extends from the bending axis BAX towards the second boundary region BA2.

[0143] That is, the extended area of ​​the first pattern portion may include a region where the width of the extended area increases or decreases.

[0144] The first pattern portion PA1 disposed in the first region 1A may include a curved surface. That is, the side surface of the first pattern portion PA1 disposed in the first region 1A may include a curved surface. However, the embodiments are not limited thereto. As the width and spacing of the first pattern portions PA1 disposed in the first region 1A vary, the side surface of the first pattern portion PA1 may include only a plane. Alternatively, as the width and spacing of the first pattern portions PA1 disposed in the first region 1A vary, the side surface of the first pattern portion PA1 may include both a flat surface and a curved surface.

[0145] In the flexible printed circuit board of this embodiment, the width of the first pattern portion disposed in the first region is greater than the width of the second pattern portion disposed in the second region. Therefore, it is possible to prevent cracks from forming in the first wiring portion located in the bending region when the flexible printed circuit board is bent.

[0146] In addition, such as Figure 7 and Figure 8 As shown, the width of the first pattern portion disposed in the first region can be varied. That is, as... Figure 7 As shown, the width of the first pattern portion disposed in the first region can gradually decrease as it moves away from the bending axis. Or, as... Figure 8 As shown, the width of the second pattern portion disposed in the second region can gradually increase as it moves away from the bending axis.

[0147] Therefore, the width of the first patterned portion can be set based on the stress value that varies according to the shape of the first region.

[0148] That is, when the shape of the first region of the flexible printed circuit board is such that the curvature decreases as it moves away from the bending axis, the stress will decrease as it moves away from the bending axis.

[0149] Therefore, as Figure 7 As shown, the width of the first pattern portion disposed in the first region can be formed to gradually decrease as it moves away from the bending axis. Therefore, it is possible to effectively prevent cracks from forming in the first wiring portion and to prevent short circuits from occurring in the first wiring portion.

[0150] Alternatively, when the first region of the flexible printed circuit board has a shape in which the curvature increases as it moves away from the bending axis, the stress will increase as it moves away from the bending axis.

[0151] Therefore, as Figure 8 As shown, the width of the first pattern portion disposed in the first region can be formed to gradually increase as it moves away from the bending axis. Therefore, it is possible to effectively prevent cracks from forming in the first wiring portion and to prevent short circuits from occurring in the first wiring portion.

[0152] Reference Figure 9 The first pattern portion PA1 of the first circuit pattern 210 can be simultaneously disposed in both the first region 1A and the second region 2A. That is, the extended region can be simultaneously disposed in both the first region 1A and the second region 2A.

[0153] The first pattern portion PA1 may have a first length L1 and a second length L2. Specifically, the first pattern portion PA1 may include a first length L1 disposed in a first region 1A and a second length L2 disposed in a second region 2A.

[0154] The first length L1 and the second length L2 may be different from each other. Specifically, the first length L1 may be greater than the second length L2. That is, the first length L1 of the first pattern portion PA1 disposed in the first region 1A may be greater than the second length L2 of the first pattern portion PA1 disposed in the second region 2A. That is, the area of ​​the first pattern portion PA1 disposed in the first region 1A may be greater than the area of ​​the first pattern portion PA1 disposed in the second region 2A.

[0155] For example, the first length L1 may be greater than or equal to 90% of the total length L of the first pattern portion PA1. Furthermore, the second length L2 may be less than or equal to 10% of the total length L of the first pattern portion PA1. Specifically, the second length L2 may be 1% to 10% of the total length L of the first wiring portion 211.

[0156] The flexible printed circuit board of the embodiment may include a first patterned portion and a second patterned portion having a width different from the first patterned portion PA1. Specifically, the flexible printed circuit board may include a first patterned portion disposed in a first region and a second region, and a second patterned portion disposed in the second region.

[0157] Furthermore, the width of the first patterned portion can be greater than the width of the second patterned portion. Therefore, by making the width of the first patterned portion disposed in the first region greater than the width of other regions, the strength of the wiring can be increased. Thus, it is possible to prevent cracks from forming in the first wiring portion disposed in the first region when the flexible printed circuit board is bent.

[0158] Furthermore, the first pattern portion can be disposed in the second region. That is, the first pattern portion can also be disposed in the second region and the second boundary region adjacent to the first boundary region. Therefore, it is possible to prevent dimensional changes in the first pattern portion located in the first region and the second region.

[0159] Alternatively, the first patterned portion can also be disposed in a second region adjacent to the first region. Therefore, even if the stress generated when the flexible printed circuit board is bent is transmitted to the second region, the reliability of the first patterned portion can be ensured.

[0160] Reference Figure 10 The second pattern portion PA2 of the first circuit pattern 210 can be simultaneously disposed in both the first region 1A and the second region 2A.

[0161] The first pattern portion PA1 and the second pattern portion PA2 may be disposed in the first region 1A. For example, the first pattern portion PA1 having a third length L3 and the second pattern portion PA2 having a fourth length L4 may be disposed in the first region 1A.

[0162] The third length L3 and the fourth length L4 may be different from each other. Specifically, the third length L3 may be greater than the fourth length L4. That is, in the first region 1A, the third length L3 of the first pattern part PA1 may be greater than the fourth length L4 of the second pattern part PA2.

[0163] For example, the third length L3 can be at least twice the fourth length L4. Specifically, the third length L3 can be 2 to 10 times the fourth length L4.

[0164] That is, in the first region 1A, the length of the wider first pattern portion PA1 can be greater than the length of the narrower second pattern portion PA2. That is, in the first region 1A, the area of ​​the wider first pattern portion PA1 can be greater than the area of ​​the narrower second pattern portion PA2.

[0165] In the flexible printed circuit board of the embodiment, such as Figure 10 As shown, the second patterned portion can also be disposed in the first region. That is, the second patterned portion can also be disposed in the first region and the second boundary region adjacent to the first boundary region. Therefore, it is possible to prevent the size of the first wiring portion from changing in the first region and the second region.

[0166] Alternatively, the second patterned portion can also be disposed in the first region adjacent to the second region. Therefore, in boundary regions where stress is low when the flexible printed circuit board is bent, it is possible to ensure that the spacing between wiring portions is greater than a predetermined size. Thus, short circuits in the first wiring portion can be prevented, and the reliability of the flexible printed circuit board can be ensured.

[0167] Reference Figure 11 and Figure 12 The first circuit pattern 210 can be formed with different thicknesses in different regions. Specifically, the first wiring portion 211 of the first circuit pattern 210 can have a thickness in each region.

[0168] Specifically, the width and spacing of the first wiring portion 211 disposed in the first region 1A may be the same as or similar to the width and spacing of the first wiring portion 211 disposed in the second region 2A.

[0169] Furthermore, the thickness of the first wiring portion 211 disposed in the first region 1A may be different from the thickness of the first wiring portion 211 disposed in the second region 2A. Specifically, the first wiring portion 211 may be formed in the first region 1A with a first thickness T1 and in the second region 2A with a second thickness T2.

[0170] At this point, the first thickness T1 and the second thickness T2 can be different. Specifically, the first thickness T1 can be greater than the second thickness T2.

[0171] That is, the thickness of the extended area of ​​the first pattern part PA1 can be greater than the thickness of the second pattern part PA2.

[0172] That is, the thickness of the first wiring portion 211 disposed in the first region 1A can be greater than the thickness of the first wiring portion disposed in the second region 2A.

[0173] In the flexible printed circuit board of the embodiment, such as Figure 11 and Figure 12As shown, the thickness of the first wiring portion disposed in the first region can be greater than the thickness of the first wiring portion disposed in the second region. Therefore, the strength of the first wiring portion disposed in the first region can be improved. Thus, it is possible to prevent cracks from forming in the first wiring portion disposed in the bending region when the flexible printed circuit board is bent.

[0174] Figure 13 This is a top view of the COF module in the embodiment.

[0175] Reference Figure 13 The COF module in this embodiment may include the flexible printed circuit board described above and a chip C disposed in the chip mounting area CA of the flexible printed circuit board 1000.

[0176] In addition, the flexible printed circuit board 1000 may include the aforementioned protective layer 300.

[0177] On the other hand, the COF module can be fabricated by mounting the chip C after cutting the second region 2A of the flexible printed circuit board 1000. Specifically, during the cutting... Figure 1 After the boundary line (cut line) CL between the first region 1A and the second region 2A in the circuit, a COF module 2000 is manufactured, in which a driver chip is installed that is electrically connected to the first circuit pattern and the second circuit pattern and is configured on the chip mounting area of ​​the flexible printed circuit board.

[0178] For example, after testing the driving characteristics of the flexible printed circuit board by means of wiring and pads configured outside the cleaving line CL, the flexible printed circuit board can be cut along the cleaving line CL.

[0179] The COF module can be located between the display panel and the substrate to connect electrical signals.

[0180] That is, the pads of the first and second circuit patterns that are exposed without the protective layer 300 are connected to the display panel, the printed circuit board, and the chip located in the chip mounting area.

[0181] Reference Figure 14 One end of the COF module 2000 of the flexible printed circuit board in the embodiment can be connected to the display panel 3000, and the other end opposite to the first end can be connected to the printed circuit board 4000.

[0182] For example, one end of the COF module 2000 of the flexible printed circuit board included in the embodiment can be electrically connected to the display panel 3000 in contact, and the other end opposite to the first end can be electrically connected to the printed circuit board 4000 in contact. Here, "contact" can refer to direct contact, or contact via an anisotropic conductive film (ACF) disposed between them.

[0183] As an example, an ACF (Acoustic Copolymer Fiber) can be configured between the COF module 2000 and the printed circuit board 4000. The COF module 2000 and the printed circuit board 4000 can be electrically connected via the ACF. The ACF can be a resin with dispersed conductive particles. Therefore, electrical signals connected through the printed circuit board 4000 can be transmitted to the COF module 2000 through the conductive particles in the ACF.

[0184] The COF module 2000 includes a flexible substrate, and therefore can be in a rigid or curved shape between the display panel 3000 and the printed circuit board 4000.

[0185] The COF module 2000 can be connected between the display panel 3000 and the printed circuit board 4000, which are arranged opposite each other, in a curved shape. Therefore, it is possible to reduce the thickness of electronic devices and increase design flexibility. In addition, the COF module 2000, which includes a flexible substrate, will not break even when bent, thus improving the reliability of electronic devices that include the COF module.

[0186] COF modules are flexible, therefore, they can be used in a variety of electronic devices.

[0187] For example, refer to Figure 15 The COF module can be incorporated into a bendable flexible touchscreen. Therefore, a touch device including the bendable flexible touchscreen can be a flexible touch device. Thus, a user can bend or fold it by hand. This type of flexible touchscreen can be applied to wearable touchscreens, etc.

[0188] Reference Figure 16 COF modules can be incorporated into a variety of wearable touch devices, including those with curved displays. This reduces the thickness or weight of electronic devices that include COF modules.

[0189] Reference Figure 17 COF modules can be used in a variety of electronic devices with displays, such as televisions, monitors, and laptops. In this case, COF modules can be used in electronic devices with curved display surfaces.

[0190] However, the embodiments are not limited to this. Of course, this flip-chip flexible printed circuit board and the COF module obtained by processing it can be used in a variety of electronic devices.

[0191] At least one embodiment of the present invention includes the features, structures, and effects described in the above embodiments, but is not limited to only one embodiment. Furthermore, those skilled in the art can combine or modify the features, structures, and effects described in the various embodiments to create other embodiments. Therefore, it should be understood that these combinations and modifications fall within the scope of the present invention.

[0192] Furthermore, while the foregoing has primarily described embodiments, these embodiments are merely examples and not intended to limit the invention. Those skilled in the art can implement various modifications and applications not shown above without departing from the essential characteristics of the embodiments. For example, modifications can be made to the various constituent elements specifically shown in the embodiments. Additionally, it should be understood that distinctions regarding such modifications and applications fall within the scope of the invention as defined by the appended claims.

Claims

1. A flexible printed circuit board, comprising: substrate; A circuit pattern is disposed on the substrate; as well as A protective layer is disposed on the circuit pattern. in, The circuit pattern includes a first circuit pattern and a second circuit pattern. The first circuit pattern includes a first pad portion, a second pad portion, and a first wiring portion connected to the first pad portion and the second pad portion. The first wiring portion includes a first pattern extending in contact with the second pad portion. The first pattern includes a first pattern portion and a second pattern portion disposed under the protective layer. The first pattern portion includes an extension area whose width is greater than the width of the second pattern portion. The maximum width of the first pattern portion is greater than the maximum width of the second pad portion. The substrate includes a bent region based on a bending axis and a non-bending region other than the bent region. The extended region is disposed on the bending region. The extended region has the minimum width in the area that overlaps with the bending axis in the vertical direction, the width of the extended region increases as it moves away from the bending axis, and the extended region has the maximum width in the area furthest away from the bending axis.

2. The flexible printed circuit board according to claim 1, wherein, The first wiring portion further includes a second pattern that is bent from the first pattern and extends in at least one direction.

3. The flexible printed circuit board according to claim 1, wherein, The second pad portion is exposed outward at the first end of the protective layer. The extended region is located within 5 mm of the first end.

4. The flexible printed circuit board according to claim 1, wherein, The spacing between the extended regions is smaller than the spacing between the second patterned portions.

5. The flexible printed circuit board according to claim 2, wherein, The first pattern is connected to the second pad portion that is attached to the display panel. The second pattern is connected to the first pad portion connected to the chip.

6. The flexible printed circuit board according to claim 1, wherein, The extended region includes a protrusion extending in the width direction of the first wiring portion. The width of the protrusion is less than 50% of the minimum interval of the first pattern portion.

7. The flexible printed circuit board according to claim 1, wherein, The side surface of the extended region includes a curved surface.

8. The flexible printed circuit board according to claim 1, wherein, The extended region is also disposed in the non-bending region. The extended region includes a first length over the bent region and a second length over the non-bent region. The first length is greater than the second length.

9. The flexible printed circuit board according to claim 8, wherein, The first length is greater than or equal to 90% of the total length of the first pattern portion.

10. The flexible printed circuit board according to claim 1, wherein, The first patterned portion is disposed in the bending area. The second patterned portion is disposed in the bent area and the non-bent area. The first pattern portion having a third length and the second pattern portion having a fourth length are disposed in the bending region. The third length is greater than the fourth length.

11. The flexible printed circuit board according to claim 10, wherein, The third length is 2 to 10 times the fourth length.

12. The flexible printed circuit board according to claim 1, in, The thickness of the extended region is greater than the thickness of the second patterned portion.

13. A COF module, comprising: The flexible printed circuit board according to claim 1; as well as A chip is disposed in the chip mounting area of ​​the flexible printed circuit board.

14. An electronic device comprising: The COF module as described in claim 13; The display panel is connected to the first circuit pattern; as well as A printed circuit board is connected to the second circuit pattern.

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