Flexible circuit board, COF module and electronic equipment comprising same

Abstract

A flexible circuit board according to an embodiment includes: a substrate having a first surface and a second surface opposite the first surface; a first circuit pattern disposed on the first surface; a second circuit pattern disposed on each of the first surface and the second surface; a third circuit pattern disposed on each of the first surface and the second surface; a first protective layer disposed on the first surface; and a second protective layer disposed on the second surface. A chip mounting area is defined on the first surface. The first circuit pattern includes: a first pad portion connected to the chip on the chip mounting area; a second pad portion connected to an external printed circuit board; and a first wiring portion connected to the first pad portion and the second pad portion. The second circuit pattern includes: a third pad portion connected to the chip; a fourth pad portion connected to an external display panel; and a second wiring portion connected to the third pad portion and the fourth pad portion. The third circuit pattern includes: a fifth pad portion connected to the chip; a sixth pad portion connected to the display panel; and a third wiring portion connected to the fifth pad portion and the sixth pad portion. The second circuit pattern includes a first via connecting the second wiring portion on the first surface and the second wiring portion on the second surface. In the second wiring portion, a first length defined as a distance from an end portion of the fourth pad portion to the first via closest to the fourth pad portion is greater than a second length defined as a length of the four pad portion.

Description

Technical Field

[0001] Embodiments relate to a flexible circuit board, a COF module, and electronic devices including the same. Background Art

[0002] In recent years, various electronic products have become thinner, smaller, and lighter. Therefore, various studies are being conducted to mount semiconductor chips at high density in narrow areas of electronic products.

[0003] Chip-on-film (COF) packaging includes a flexible substrate. Therefore, COF can be applied to flexible displays. For example, COF can be used in various wearable electronic devices. Furthermore, COF methods can form fine pitches, making COF applicable to high-resolution displays.

[0004] The COF is mounted on a flexible circuit board in the form of a thin film with a semiconductor chip. For example, the semiconductor chip may be an integrated circuit (IC) chip or a large-scale integrated circuit (LSI) chip.

[0005] The chip can be connected to an external circuit board and display panel via a circuit pattern. For example, pads are provided at one end and the other end of the circuit pattern. One pad is electrically connected to a terminal of the chip. Furthermore, another pad can be connected to a terminal of the display panel and the circuit board. Thus, the chip, circuit board, and display panel are electrically connected via the COF. Therefore, signals can be transmitted to the display panel via the circuit pattern.

[0006] At the same time, the flexible circuit board can be flexible. Therefore, when the flexible circuit board is connected to the circuit board and the display panel, the flexible circuit board can be bent in one direction. That is, the flexible circuit board includes a bending area.

[0007] When the bent region overlaps the through-hole, the position of the through-hole may be changed due to stress.

[0008] Therefore, there is a need for a flexible circuit board, a COF module, and an electronic device including the same having a new structure that can solve the above problems.

[0009] Korean Patent No. KR10-0618898 (2006.09.01) was disclosed as a patent related to a flexible circuit board. Summary of the Invention

[0010] Technical issues

[0011] The embodiments provide flexible circuit boards having various designs, COF modules, and electronic devices including the same.

[0012] The embodiment provides a flexible circuit board with improved reliability, a COF module, and an electronic device including the same.

[0013] Technical Solution

[0014] 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 first circuit pattern provided on the first surface; a second circuit pattern provided on the first surface and the second surface; a third circuit pattern provided on the first surface and the second surface; a first protective layer provided on the first surface; and a second protective layer provided on the second surface, wherein a chip mounting area is defined on the first surface, wherein the first circuit pattern includes a first pad portion connected to a chip on the chip mounting area, a second pad portion connected to an external printed circuit board, and a first wiring portion connected to the first pad portion and the second pad portion, wherein the second circuit pattern includes a first wiring portion connected to a first pad portion and a second wiring portion. a third pad portion of the chip, a fourth pad portion connected to the external display panel, and a second wiring portion connected to the third pad portion and the fourth pad portion, wherein the third circuit pattern includes a fifth pad portion connected to the chip, a sixth pad portion connected to the display panel, and a third wiring portion connected to the fifth pad portion and the sixth pad portion, wherein the second circuit pattern includes a first through-hole connecting the second wiring portion on the first surface and the second wiring portion on the second surface, wherein a first length and a second length are defined in the second wiring portion, the first length is the distance from the end of the fourth pad portion to the first through-hole closest to the fourth pad portion, the second length is the length of the fourth pad portion, and wherein the first length is longer than the second length.

[0015] Beneficial effects

[0016] The flexible circuit board according to the embodiment can control a first length of the area between the pad portion and the through hole. The first length is defined as the length from the end of the second protection layer to the first through hole in the first through hole group closest to the end.

[0017] Therefore, the flexible circuit board according to the embodiment can be bent again in the region having the first length, and thus the frame area of ​​the display panel can be reduced.

[0018] Furthermore, the flexible circuit board does not bend in the region where the through-hole is provided.

[0019] Therefore, when the flexible circuit board is bent, stress can be prevented from being transferred to the through-holes. Therefore, the alignment of the through-holes can be prevented from being misaligned due to stress. In addition, the shape or size of the through-holes can be prevented from being changed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a diagram for explaining a top view of a flexible circuit board according to an embodiment.

[0021] Figure 2is a diagram for explaining a bottom view of a flexible circuit board according to an embodiment.

[0022] Figure 3 It shows Figure 1 FIG is an enlarged view of area A.

[0023] Figure 4 It shows Figure 1 FIG is an enlarged view of area B.

[0024] Figure 5 It shows Figure 2 FIG is an enlarged view of area C.

[0025] Figure 6 It shows Figure 2 FIG is a diagram of an enlarged view of area D.

[0026] Figure 7 It shows Figure 1 FIG is a diagram of an enlarged view of area E.

[0027] Figure 8 It shows Figure 1 FIG is a diagram of an enlarged view of area F.

[0028] Figure 9 and Figure 10 A diagram for explaining the curved shape of a COF module.

[0029] Figure 11 It shows Figure 2 FIG is a diagram of an enlarged view of area G.

[0030] Figure 12 and Figure 13 is a diagram for explaining a bent shape of a COF module according to an embodiment.

[0031] Figure 14 and Figure 15 It is along Figure 3 A cross-sectional view taken along the area AA'.

[0032] Figures 16 to 19 2 are diagrams illustrating various bent shapes of a COF module including a flexible circuit board according to an embodiment.

[0033] Figures 20 to 22 is a diagram of an electronic device including a flexible circuit board according to an embodiment. DETAILED DESCRIPTION

[0034] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, the spirit and scope of the present disclosure are not limited to the parts of the described embodiments, but can be implemented in various other forms, and one or more of the elements of the embodiments can be selectively combined and rearranged within the spirit and scope of the present disclosure.

[0035] In addition, unless otherwise explicitly defined and described, the terms (including technical and scientific terms) used in the embodiments of the present disclosure may be interpreted as having the same meaning as that commonly understood by ordinary technicians in the field to which the present disclosure belongs, and terms (such as those defined in commonly used dictionaries) may be interpreted as having a meaning consistent with the meaning in the context of its relevant technology.

[0036] In addition, the terms used in the embodiments of the present disclosure are used to describe the embodiments and are not intended to limit the present disclosure. In this specification, unless otherwise specified in a phrase, a singular form may also include a plural form, and when described as "at least one (or more) of A (and), B and C", it may include at least one of all possible combinations of A, B and C.

[0037] In addition, when describing the elements of the embodiments of the present disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish an element from other elements, and these terms do not limit the nature, order, or sequence of the elements.

[0038] In addition, when an element is described as being “connected,” “coupled” or “in contact with” another element, it may include not only the case where the element is directly “connected,” “coupled” or “in contact with” the other element, but also the case where the element is “connected,” “coupled” or “in contact with” the other element through another element between the element and the other element.

[0039] In addition, when described as being formed or arranged "on (above)" or "under (below)" each element, "on (above)" or "under (below)" may include not only the case where two elements are directly connected to each other, but also the case where one or more other elements are formed or arranged between the two elements.

[0040] In addition, when the expression "upper" or "lower" is used, not only an upper direction based on one element but also a lower direction based on one element may be included.

[0041] In addition, in the following description, the first direction 1D may be defined as being in a width direction of the flexible circuit board, and the second direction 2D may be defined as being in a length direction of the flexible circuit board.

[0042] Meanwhile, in the following drawings, for the convenience of explanation, all circuit patterns disposed under the protective layer are drawn with solid lines.

[0043] Hereinafter, a flexible circuit board, a COF module, and an electronic device including the same according to embodiments will be described with reference to the accompanying drawings.

[0044] refer to Figures 1 to 6 , the flexible circuit board 1000 according to the embodiment may include a substrate 100 , a circuit pattern, and a protective layer.

[0045] The substrate 100 includes a first surface 1S and a second surface 2S opposite to the first surface. Circuit patterns and a protective layer may be provided on the first surface 1S and the second surface 2S.

[0046] The substrate 100 may include a cutting line CL. The flexible circuit board 1000 may be cut along the cutting line CL. In detail, the circuit pattern, the protective layer, and the chip are provided on the substrate 100. Next, the substrate 100 is cut along the cutting line CL. Thus, the COF module 2000 may be manufactured.

[0047] The substrate 100 may include an active area AA and an unactive area UA. The active area AA and the unactive area UA may be distinguished by a cutting line CL. Specifically, the active area AA may be defined as an inner area of ​​the cutting line CL. Furthermore, the unactive area UA may be defined as an outer area of ​​the cutting line CL.

[0048] The circuit pattern, protective layer, and chip can be arranged in the active area AA. Furthermore, dummy patterns and sprocket holes SH can be arranged in the unactive area UA. The dummy patterns can enhance the strength of the substrate 100, thereby preventing the flexible circuit board 1000 from bending. Furthermore, the flexible circuit board 1000 can be rolled or unrolled in a roll-to-roll manner through the sprocket holes SH.

[0049] The substrate 100 may include a chip mounting area CHA. The chip mounting area CHA may be disposed within the active area AA. A chip is disposed within the chip mounting area CHA. Furthermore, a pad portion of a circuit pattern may be disposed within the chip mounting area CHA. Furthermore, a protective layer is not disposed on the chip mounting area CHA.

[0050] The substrate 100 may include a flexible material. For example, the substrate 100 may include polyimide (PI). However, the embodiment is not limited thereto. The substrate 100 may include a polymer material, such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).

[0051] The thickness of substrate 100 may be 20 μm to 100 μm. For example, the thickness of substrate 100 may be 25 μm to 50 μm. For example, the thickness of substrate 100 may be 30 μm to 40 μm. If the thickness of substrate 100 exceeds 100 μm, the overall thickness of the flexible circuit board may increase. As a result, the flexibility of the flexible circuit board may be reduced. In addition, if the thickness of substrate 100 is less than 20 μm, flexible circuit board 1000 may be damaged. Specifically, when a chip is mounted on flexible circuit board 1000, heat and pressure are transferred to substrate 100. As a result, the substrate may be damaged.

[0052] A circuit pattern and a protective layer may be provided on the substrate 100. In detail, the circuit pattern and the protective layer may be provided in the active area AA and the unactive area UA.

[0053] The circuit pattern may include a first circuit pattern 210 , a second circuit pattern 220 , a third circuit pattern 230 , and a fourth circuit pattern 240 . In addition, the protective layer may include a first protective layer 310 and a second protective layer 320 .

[0054] refer to Figure 1 and Figure 3 , the first circuit pattern 210 may be provided on the first surface 1S. The first circuit pattern 210 may include 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.

[0055] The first pad portion 212a may be provided inside the chip mounting area CHA. Therefore, the first pad portion 212a may be connected to a terminal of the chip. Therefore, the first circuit pattern 210 may be connected to the chip.

[0056] In addition, the second pad portion 212b may be provided outside the chip mounting area CHA. The second pad portion 212b may be connected to a terminal of an external circuit board. Therefore, the first circuit pattern 210 may be connected to the circuit board.

[0057] Meanwhile, the second pad portion 212b may be a first test pad portion. Specifically, the first circuit pattern 210 may be tested before the circuit board is connected to the second pad portion 212b. For example, the second pad portion 212b may be used to check whether the first circuit pattern is open or shorted.

[0058] In addition, the first wiring portion 211 can be provided between the first pad portion 212a and the second pad portion 212b. That is, the first wiring portion 211 can connect the first pad portion 212a and the second pad portion 212b. Thus, the chip can be connected to the circuit board. Thus, the signal generated by the chip can be transmitted to the circuit board.

[0059] The first protective layer 310 may be disposed on the first circuit pattern 210. In detail, the first protective layer 310 may be disposed on a region excluding the first and second pad portions 212a and 212b.

[0060] refer to Figure 1 、 Figure 2 、 Figure 4 and Figure 5 The second circuit pattern 220 may be provided on the first surface 1S and the second surface 2S. The second circuit pattern 220 may include second wiring portions 221a and 221b, a third pad portion 222a, a fourth pad portion 222b, and a first through hole V1. The second wiring portions 221a and 221b, the third pad portion 222a, and the fourth pad portion 222b may include the same material. In addition, the second wiring portions 221a and 221b, the third pad portion 222a, and the fourth pad portion 222b may be integrally formed.

[0061] In addition, the first protective layer 310 or the second protective layer 320 is provided on the second wiring portions 221a and 221b. In addition, the first protective layer 310 or the second protective layer 320 is not provided on the third pad portion 222a and the fourth pad portion 222b.

[0062] The third pad portion 222a may be provided on the first surface 1S. The third pad portion 222a may be provided inside the chip mounting area CHA. Therefore, the third pad portion 222a may be connected to the terminal of the chip. Therefore, the second circuit pattern 220 may be connected to the chip.

[0063] In addition, the fourth pad portion 222b may be provided on the second surface 2S. The fourth pad portion 222b may be connected to a terminal of an external display panel. Therefore, the second circuit pattern 220 may be connected to the display panel.

[0064] The second wiring portion may include a second-first wiring portion 221a and a second-second wiring portion 221b. The second-first wiring portion 221a is disposed on the first surface 1S. The second-second wiring portion 221b is disposed on the second surface 2S. The second wiring portion may connect the third pad portion 222a and the fourth pad portion 222b. Specifically, the second-first wiring portion 221a may be connected to the third pad portion 222a. Furthermore, the second-second wiring portion 221b may be connected to the fourth pad portion 222b.

[0065] Therefore, the chip can be connected to the display panel. Therefore, the signal generated from the chip can be transmitted to the display panel.

[0066] The first protective layer 310 and the second protective layer 320 may be provided on the second circuit pattern 220. Specifically, the first protective layer 310 may be provided on the second circuit pattern 220 on the first surface 1S. In addition, the second protective layer 320 may be provided on the second circuit pattern 220 on the second surface 2S. The first protective layer 310 and the second protective layer 320 may be provided on areas other than the third pad portion 222a and the fourth pad portion 222b.

[0067] The second-first wiring portion 221a and the second-second wiring portion 221b may be connected to each other. Specifically, the second-first wiring portion 221a and the second-second wiring portion 221b may be connected via a first through-hole V1. The first through-hole V1 may be provided on the first surface 1S and the second surface 2S. The first through-hole V1 on the first surface 1S and the first through-hole V1 on the second surface 2S may be provided at positions corresponding to each other.

[0068] The first via V1 includes a first via land VL1 and a first via body VH1. The first via body VH1 is formed inside the first via land VL1. A conductive material may be provided in the first via body VH1. Thus, the second-first wiring portion 221a and the second-second wiring portion 221b may be electrically connected.

[0069] Meanwhile, the second circuit pattern 220 may include a second test pad portion TP2. The second test pad portion TP2 may be disposed on the second surface 2S. The second test pad portion TP2 may be disposed in the unactive area UA. In addition, the second protective layer 320 is not disposed on the second test pad portion TP2. The second test pad portion TP2 may be connected to the second-second wiring portion 221b. In detail, the second test pad portion TP2 may be integrally formed with the second-second wiring portion 221b.

[0070] Before connecting the display panel and the fourth pad portion 222b, the second circuit pattern 220 may be tested. For example, the second test pad portion TP2 may be used to check whether the second circuit pattern is open or shorted.

[0071] refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 6The third circuit pattern 230 may be disposed on the first surface 1S and the second surface 2S. The third circuit pattern 230 may include a third wiring portion 231, a fifth pad portion 232a, a sixth pad portion 232b, and a second through hole V2. The third wiring portion 231, the fifth pad portion 232a, and the sixth pad portion 232b may be made of the same material. Furthermore, the third wiring portion 231, the fifth pad portion 232a, and the sixth pad portion 232b may be integrally formed.

[0072] The fifth pad portion 232a may be provided on the first surface 1S. The fifth pad portion 232a may be provided inside the chip mounting area CHA. Therefore, the fifth pad portion 232a may be connected to a terminal of the chip. Thus, the third circuit pattern 230 may be connected to the chip.

[0073] In addition, the sixth pad portion 232b may be provided on the second surface 2S. The sixth pad portion 232b may be connected to a terminal of an external display panel. Thus, the third circuit pattern 230 may be connected to the display panel.

[0074] In addition, the third wiring portion 231 can connect the fifth pad portion 232a and the sixth pad portion 232b. Therefore, the chip can be connected to the display panel. Therefore, the signal generated from the chip can be transmitted to the display panel.

[0075] The first protective layer 310 and the second protective layer 320 may be provided on the third circuit pattern 230. Specifically, the first protective layer 310 may be provided on the third circuit pattern 230 on the first surface 1S. In addition, the second protective layer 320 may be provided on the third circuit pattern 230 on the second surface 2S. The first protective layer 310 and the second protective layer 320 may be provided on the area other than the fifth pad portion 232a and the sixth pad portion 232b.

[0076] The fifth pad portion 232a and the third wiring portion 231 on the second surface 2S may be connected to each other. Specifically, the fifth pad portion 232a and the third wiring portion 231 may be connected via a second through hole V2. The second through hole V2 may be provided on the first surface 1S and the second surface 2S. The second through hole V2 on the first surface 1S and the second through hole V2 on the second surface 2S may be provided at positions corresponding to each other.

[0077] The second via V2 includes a second via land VL2 and a second via body VH2. The second via body VH2 is formed inside the second via land VL2. A conductive material may be provided in the second via body VH2. Therefore, the fifth pad portion 232a and the third wiring portion 231 may be electrically connected.

[0078] Meanwhile, the third circuit pattern 230 may include a third test pad portion TP3. The third test pad portion TP3 may be disposed on the second surface 2S. The third test pad portion TP3 may be disposed in the unactive area UA. In addition, the second protective layer 320 is not disposed on the third test pad portion TP3. The third test pad portion TP3 may be connected to the third wiring portion 231. In detail, the third test pad portion TP3 may be integrally formed with the third wiring portion 231.

[0079] Before connecting the display panel and the sixth pad portion 232b, the third circuit pattern 230 may be tested. For example, the third test pad portion TP3 may be used to check whether the third circuit pattern is open or shorted.

[0080] refer to Figure 1 、 Figure 7 and Figure 8 The fourth circuit pattern 240 may be disposed on the first surface 1S and the second surface 2S. The fourth circuit pattern 240 may include fourth wiring portions 241a and 241b, a seventh pad portion 242a, an eighth pad portion 242b, and a third through hole V3. The fourth wiring portions 241a and 241b, the seventh pad portion 242a, and the eighth pad portion 242b may be made of the same material. In addition, the fourth wiring portions 241a and 241b, the seventh pad portion 242a, and the eighth pad portion 242b may be integrally formed.

[0081] The seventh pad portion 242a may be disposed on the first surface 1S. The seventh pad portion 242a may be disposed adjacent to the first pad portion 212a. The seventh pad portion 242a may be connected to a terminal of an external circuit board. Thus, the fourth circuit pattern 220 may be connected to the circuit board.

[0082] In addition, the eighth pad portion 242b may be provided on the second surface 2S. The eighth pad portion 242b may be connected to a terminal of an external display panel. Therefore, the fourth circuit pattern 240 may be connected to the display panel.

[0083] The fourth wiring portion may include a fourth-first wiring portion 241a and a fourth-second wiring portion 241b. The fourth-first wiring portion 241a is disposed on the first surface 1S. The fourth-second wiring portion 241b is disposed on the second surface 2S. The fourth wiring portion may connect the seventh pad portion 242a and the eighth pad portion 242b. Specifically, the fourth-first wiring portion 241a may be connected to the seventh pad portion 242a. Furthermore, the fourth-second wiring portion 241b may be connected to the eighth pad portion 242b.

[0084] The fourth circuit pattern 240 may be a power pattern, and power may be transmitted to the circuit board and the display panel through the fourth circuit pattern 240 .

[0085] The first protective layer 310 and the second protective layer 320 may be provided on the fourth circuit pattern 240. Specifically, the first protective layer 310 may be provided on the fourth circuit pattern 240 on the first surface 1S. In addition, the second protective layer 320 may be provided on the fourth circuit pattern 240 on the second surface 2S. The first protective layer 310 and the second protective layer 320 may be provided on areas other than the seventh pad portion 242a and the eighth pad portion 242b.

[0086] The fourth-first wiring portion 241a and the fourth-second wiring portion 241b may be connected to each other. Specifically, the fourth-first wiring portion 241a and the fourth-second wiring portion 241b may be connected via a third through-hole V3. The third through-hole V3 may be provided on the first surface 1S and the second surface 2S. The third through-hole V3 on the first surface 1S and the third through-hole V3 on the second surface 2S may be provided at corresponding positions.

[0087] The third via V3 includes a third via land VL3 and a third via body VH3. The third via body VH3 is formed inside the third via land VL3. A conductive material may be provided in the third via body VH3. Thus, the fourth-first wiring portion 241a and the fourth-second wiring portion 241b may be electrically connected.

[0088] At least one of the first circuit pattern 210, the second circuit pattern 220, the third circuit pattern 230, and the fourth circuit pattern 240 may include a metal material having excellent electrical conductivity. Specifically, at least one of the first circuit pattern 210, the second circuit pattern 220, the third circuit pattern 230, and the fourth circuit pattern 240 may include copper (Cu). However, embodiments are not limited thereto. At least one of the first circuit pattern 210, the second circuit pattern 220, the third circuit pattern 230, and the fourth circuit pattern 240 may include at least one metal selected from the group consisting of copper (Cu), aluminum (Al), chromium (Cr), nickel (Ni), silver (Ag), molybdenum (Mo), gold (Au), titanium (Ti), and alloys thereof.

[0089] In addition, at least one of the first protective layer 310 and the second protective layer 320 may include solder paste. For example, at least one of the first protective layer 310 and the second protective layer 320 may include solder paste including thermosetting resin, thermoplastic resin, filler, curing agent, or curing accelerator.

[0090] As described above, the second circuit pattern 220 may include a first through hole V1. Specifically, the second circuit pattern 220 may include a plurality of first through holes V1. The number of first through holes V1 may correspond to the number of pad portions of the second circuit pattern 220. Therefore, the number of first through holes V1 may be proportional to the number of terminals of the display panel.

[0091] For example, when the flexible circuit board is connected to a VR display panel having a large number of terminals, the number of first through holes V1 may increase. In addition, the first through holes V1 may be arranged in various ways according to the width of the flexible circuit board in the first direction 1D and the length in the second direction 2D.

[0092] For example, a plurality of first through hole groups VG1 may be defined. The first through hole group VG1 includes a plurality of first through holes V1 arranged along the second direction 2D. In addition, the first through hole groups VG1 may be spaced apart in the first direction 1D.

[0093] The number of first through hole groups VG1 may vary depending on the width of the flexible circuit board 1000 in the first direction 1D and the length in the second direction 2D.

[0094] For example, when the width of the flexible circuit board 1000 is large, the number of first through holes V1 in the first through hole group VG1 can be reduced. Alternatively, the number of first through hole groups VG1 can be increased. For example, a flexible circuit board connected to a mobile display panel can have a large width. Therefore, the number of first through holes V1 in the first through hole group VG1 of the flexible circuit board connected to the mobile display panel can be small. Alternatively, the number of first through hole groups VG1 can be increased.

[0095] Alternatively, when the width of the flexible circuit board 1000 is small, the number of first through holes V1 in the first through hole group VG1 can be increased. Furthermore, the number of first through hole groups VG1 can be reduced. For example, the flexible circuit board connected to the VR display panel can have a smaller width. Therefore, the number of first through holes V1 in the first through hole group VG1 of the flexible circuit board connected to the VR display panel can be larger. Furthermore, the number of first through hole groups VG1 can be smaller.

[0096] Meanwhile, the flexible circuit board 1000 may include a first isolation area IA1, a second isolation area IA2, and a third isolation area IA3. The first isolation area IA1 may be defined as the area between the fourth pad portion 222b and the first through hole V1 closest to the fourth pad portion 222b. Furthermore, the second isolation area IA2 may be defined as the area between the first through hole V1 closest to the fourth pad portion 222b and the cutting line CL. Furthermore, the third isolation area IA3 may be defined as the area between the sixth pad portion 232b and the chip mounting area CHA.

[0097] The COF module 2000 can be bent. Figure 2 as well as Figure 9(a) and (b), the COF module 2000 may be bent in the third isolation area IA3. Therefore, the COF module 2000 includes a bending area BA. In detail, the third isolation area IA3 includes the bending area BA.

[0098] Therefore, the first and second partition areas IA1 and IA2 may overlap with the display panel 4000. Therefore, the first and second partition areas IA1 and IA2 may become the frame areas of the display panel 4000. Figure 9 As shown in (b), when the lengths of the first and second separation areas IA1 and IA2 increase, the bezel area of ​​the display panel 4000 may increase.

[0099] For example, when the number of first through holes V1 in the first through hole group VG1 increases, the length of the second isolation area IA2 can increase. Consequently, the bezel area of ​​the display panel 4000 can be increased. For example, in the case of the COF module 2000 connected to a VR display panel, the number of first through holes V1 in the first through hole group VG1 is large. Consequently, the length of the second isolation area IA2 increases, thereby increasing the bezel area BE of the display panel 4000.

[0100] Alternatively, if the size of the first through holes V1 in the first through hole group VG1 increases, the bezel area of ​​the display panel 4000 can be increased. For example, in the case of the COF module 2000 connected to a mobile display panel, the number of first through holes V1 in the first through hole group VG1 is small. However, the size of the first through holes V1 can be increased. As a result, the length of the second isolation area IA2 increases, thereby increasing the bezel area BE of the display panel 4000.

[0101] Therefore, the COF module 2000 according to the embodiment may be bent in at least two regions. Figure 10 , COF module 2000 may include a first bending area BA1 and a second bending area BA2. In this case, when the first via V1 is disposed in the second bending area BA2, stress may be transferred to the first via V1. As a result, the size or shape of the first via plate VL1 and the first via body VH1 may change. Consequently, the alignment of the first via body VH1 may be misaligned.

[0102] The following will describe a flexible circuit board 1000 and a COF module that can solve the above problems.

[0103] Figure 11 yes Figure 2 Magnified view of region G.

[0104] refer to Figure 11, the second circuit pattern 220 may have a length range set for each region. In detail, the second circuit pattern 220 may be defined to have a first length L1, a second length L2, a third length L3, a fourth length L4, and a fifth length L5.

[0105] The first length L1 can be defined as the length from the end E1 of the second protective layer 320 to the first through hole V1 closest to the fourth pad portion 222b. In other words, the first length L1 can be defined as the length from the end E1 of the second protective layer 320 to the first through hole V1 closest to the end E1 of the second protective layer in the first through hole group VG1. In addition, the first length L1 can be defined as the length from the end of the fourth pad portion 222b to the first through hole V1 closest to the end of the first through hole group VG1. The first length L1 can be defined as the length of the first isolation area IA1.

[0106] In addition, the second length L2 may be defined as the length of the fourth pad portion 222b.

[0107] In addition, the third length L3 may be defined as the length from the first through hole V1 closest to the fourth pad portion 222b to the first through hole V1 farthest from the fourth pad portion 222b. That is, the third length L3 may be defined as the length from the closest first through hole V1 in the first through hole group VG1 to the farthest first through hole V1 in the first through hole group VG1.

[0108] In addition, the fourth length L4 can be defined as the length from the first through hole V1 farthest from the fourth pad portion 222b to the cutting line CL. That is, the fourth length L4 can be defined as the length from the farthest first through hole V1 in the first through hole group VG1 to the cutting line CL. That is, the fourth length L4 can be defined as the distance from the farthest first through hole V1 in the first through hole group VG1 to the end of the COF module.

[0109] The sum of the third length L3 and the fourth length V4 may be defined as the length of the second separation area IA2 .

[0110] The first length L1 may be greater than the second length L2. For example, the first length L1 may be 1.5 times or greater than the second length L2. Specifically, the first length L1 may be 1.5 to 10 times, 2 to 5 times, or 2.5 to 3.5 times the second length L2.

[0111] Furthermore, the first length L1 may be greater than the length L5 of the first through hole V1. For example, the first length L1 may be 15 times or greater than the length L5 of the first through hole V1. Specifically, the first length L1 may be 15 to 35 times, 20 to 35 times, or 25 to 35 times the length L5 of the first through hole V1.

[0112] In addition, the first length L1 may be smaller than the third length L3. For example, the first length L1 may be 0.8 times or less of the third length L3. Specifically, the first length L1 may be 0.3 to 0.8 times, 0.4 to 0.7 times, or 0.5 to 0.6 times the third length L3.

[0113] In addition, the first length L1 may be greater than the fourth length L4. For example, the first length L1 may be 1.5 times or greater than the fourth length L4. Specifically, the first length L1 may be 1.5 to 10 times, 2 to 9 times, or 3 to 8.5 times the fourth length L4.

[0114] For example, the first length L1 may be 5 mm or less. In detail, the first length L1 may be 0.1 to 4 mm, 0.5 to 3 mm, or 1 to 2.5 mm.

[0115] In addition, the second length L2 may be 0.5 to 1 mm or 0.7 to 0.9 mm.

[0116] In addition, the third length L3 may be 1 to 4 mm, 2 to 3.5 mm, or 2.5 to 3.3 mm.

[0117] In addition, the fourth length L4 may be 0.15 mm to 0.6 mm, 0.2 mm to 0.5 mm, or 0.25 mm to 0.4 mm.

[0118] Since the first length L1 satisfies the above range, the flexible circuit board 1000 can be bent in the first isolation area IA1. That is, the size of the first isolation area IA1 is sufficiently guaranteed. Therefore, the flexible circuit board 1000 can be bent at least once in the first isolation area IA1.

[0119] The first separation area IA1 may include a first-first separation area IA1a, a first-second separation area IA1b, and a first-third separation area IA1c. The first-second separation area IA1b may be disposed between the first-first separation area IA1a and the first-third separation area IA1c.

[0120] refer to Figure 13 The flexible circuit board 1000 may be bent at the third separation area IA3 and the first-second separation area IA1b. Therefore, the frame area of ​​the display panel 4000 may be reduced.

[0121] refer to Figure 12The flexible circuit board 1000 includes a bending area BA. Specifically, the third isolation area IA3 includes the bending area BA. If the flexible circuit board 1000 is bent only at the third isolation area IA3, the first bezel area BE1 of the display panel 4000 may be increased. Specifically, the first bezel area BE1 includes a portion of the third isolation area IA3, a first-first isolation area IA1a, a first-second isolation area IA1b, a first-third isolation area IA1c, and a second isolation area IA2.

[0122] However, reference Figure 13 The flexible circuit board 1000 includes a first bending area BA1 and a second bending area BA2. The third partition area IA3 includes the first bending area BA1. Furthermore, the first-second partition area IA1b includes the second bending area BA2. If the third partition area IA3 and the first-second partition area IA1b are bent, the second bezel area BE2 of the display panel 4000 is reduced. Specifically, the second bezel area BE2 includes a portion of the third partition area IA3, the first-first partition area IA1a, and a portion of the first-second partition area IA1b.

[0123] exist Figure 13 In FIG. 5 , the first-second separation area IA1b is shown as being bent only once. However, the embodiment is not limited thereto. For example, the first-second separation area IA1b may be bent at least twice. That is, the first-second separation area IA1b may include at least two bending areas.

[0124] The flexible circuit board 1000 according to the embodiment is bent at the first separation area IA1 , and thus, the bezel area of ​​the display panel can be reduced.

[0125] In addition, the flexible circuit board is not bent at the second isolation area IA2. Therefore, the flexible circuit board 1000 is not bent in the area where the first through hole V1 is formed.

[0126] Therefore, when the flexible circuit board 1000 is bent, stress can be prevented from being transferred to the first through hole. Therefore, the alignment of the first through hole can be prevented from being misaligned due to stress. In addition, the shape or size of the first through hole can be prevented from changing.

[0127] Below, we will refer to Figure 14 and Figure 15 The layer structures of the first circuit pattern, the second circuit pattern, the third circuit pattern, and the fourth circuit pattern are described. For ease of explanation, the description will focus on the first circuit pattern. The following description applies to all of the second circuit pattern, the third circuit pattern, and the fourth circuit pattern.

[0128] refer to Figure 14, the first circuit pattern may be formed in multiple layers. In detail, the first wiring portion 211 and the first pad portion 212a may include a first metal layer 201 and a second metal layer 202. In addition, although Figure 14 Although not shown in the figure, the second pad portion 212 b may also include the first metal layer 201 and the second metal layer 202 .

[0129] The first metal layer 201 may be a seed layer of the first circuit pattern. For example, the first metal layer 201 may be formed on the substrate 100 by electroless plating using a metal material such as copper (Cu).

[0130] In addition, the second metal layer 202 may be a plated layer. For example, the first metal layer 201 is used as a seed layer and the second metal layer 202 is formed by electroplating.

[0131] The thickness of the first metal layer 201 may be smaller than the thickness of the second metal layer 202 .

[0132] For example, the thickness of the first metal layer 201 may be 0.7 μm to 2 μm, and the thickness of the second metal layer 202 may be 10 μm to 25 μm.

[0133] The first metal layer 201 and the second metal layer 202 may include the same metal material. For example, the first metal layer 201 and the second metal layer 202 may include copper (Cu).

[0134] Furthermore, the bonding layer 203 may be provided on the second metal layer 201. Specifically, the bonding layer 203 may be provided 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 provided to surround the first metal layer 201 and the second metal layer 202.

[0135] The bonding layer 203 may include metal. In detail, the bonding layer 203 may include tin (Sn).

[0136] The bonding layer 203 may be formed to a thickness of 0.3 μm to 0.7 μm. The content of tin may increase as the bonding layer 203 extends from the lower surface to the upper surface.

[0137] That is, the bonding layer 203 is disposed in contact with the second metal layer 202. Therefore, as the bonding layer 203 extends from the lower surface to the upper surface, the content of tin may increase, and the content of copper may decrease.

[0138] Therefore, only pure tin with a thickness ranging from 0.1 μm to 0.3 μm remains on the upper surface of the bonding layer 203 .

[0139] The bonding layer 203 allows chip terminals, circuit board terminals, display panel terminals, and pads to be easily bonded together using heat and pressure. Specifically, when heat and pressure are applied to the pads, the upper surface of the bonding layer, where pure tin is present, melts. This allows the chip terminals, circuit board terminals, and display panel terminals to be easily bonded together.

[0140] Therefore, the bonding layer 203 may be a portion of the first pad portion 212 a and a portion of the second pad portion 222 b .

[0141] The first circuit pattern may be provided with a thickness of 2 μm to 25 μm. For example, the first circuit pattern may be provided with a thickness of 5 μm to 20 μm. For example, the first circuit pattern may be provided with a thickness of 7 μm to 15 μm.

[0142] When forming the first circuit pattern, flash etching is performed to separate the circuit patterns. As a result, the first metal layer 201 is etched. Therefore, the thickness of the first circuit pattern ultimately produced may be less than the sum of the thicknesses of the first metal layer 201, the second metal layer 202, and the bonding layer 203 formed during this process.

[0143] If the thickness of the first circuit pattern is less than 2 μm, the resistance of the second circuit pattern may increase. If the thickness of the first circuit pattern exceeds 25 μm, it may be difficult to achieve a fine pattern.

[0144] Meanwhile, a buffer layer 205 may be further provided between the substrate 100 and the first circuit pattern. The buffer layer 205 may improve adhesion between the substrate 100 and the first circuit pattern (which are different materials).

[0145] The buffer layer 205 may be formed in multiple layers. Specifically, a first buffer layer 205a and a second buffer layer 205b on the first buffer layer 205a may be provided on the substrate 100. Thus, the first buffer layer 205a may be in contact with the substrate 100. The second buffer layer 205b may be in contact with the first circuit pattern 210.

[0146] The first buffer layer 205a may include 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 may include a material having good adhesion to the second circuit pattern. For example, the second buffer layer 205b may include chromium (Cr).

[0147] The buffer layer 205 may have a film thickness in nanometers. For example, the buffer layer 205 may have a thickness of 20 nm or less.

[0148] Adhesion between the substrate 100 and the first circuit pattern (being a different material) may be improved by the buffer layer 205. Therefore, delamination of the first circuit pattern may be prevented.

[0149] refer to Figure 15 The bonding layer 203 may include a plurality of bonding layers. For example, the bonding layer 203 may include a first bonding layer 203a and a second bonding layer 203b.

[0150] In detail, the first bonding layer 203 a may be disposed on the first wiring portion 211 , the first pad portion 212 a , and the second pad portion 212 b .

[0151] In addition, the second bonding layer 203b may be provided only on the first and second pad portions 212a and 212b. That is, the first wiring portion 211, the first and second pad portions 212a and 212b may have different layer structures due to the second bonding layer 203b.

[0152] The first bonding layer 203a and the second bonding layer 203b may include metal. In detail, the first bonding layer 203a and the second bonding layer 203b may include tin (Sn).

[0153] The first bonding layer 203a and the second bonding layer 203b may be provided with different thicknesses. In detail, the second bonding layer 203b may be thicker than the first bonding layer 203a.

[0154] For example, the first bonding layer 203a may have a 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.

[0155] If the bonding layer is thicker in the area between the protective layer 300 and the first wiring portion 211, cracks may occur when the flexible circuit board is bent. Therefore, the first bonding layer 203a can be formed with a thin film thickness. This can prevent cracks from occurring when the flexible circuit board is bent.

[0156] In addition, the content of tin may increase as the second bonding layer 203 b extends from the lower surface to the upper surface.

[0157] That is, the tin content of the second bonding layer 203 b may increase from the lower surface to the upper surface, while the copper content of the second bonding layer 203 b may decrease from the lower surface to the upper surface.

[0158] Therefore, only pure tin with a thickness ranging from 0.1 μm to 0.3 μm remains on the upper surface of the second bonding layer 203 b .

[0159] The chip terminals, the circuit board terminals, the display panel terminals, and the pad portion can be easily bonded together using heat and pressure with the help of the second bonding layer 203b. Specifically, when heat and pressure are applied to the pad portion, the upper surface of the bonding layer containing the remaining pure tin melts. As a result, the chip terminals, the circuit board terminals, and the display panel terminals can be easily bonded together.

[0160] The flexible printed circuit board can be bent into various shapes. The COF module 2000 can be bent into various shapes.

[0161] Figures 16 to 19 2 are diagrams illustrating various shapes in which a COF module including a flexible circuit board is bent according to an embodiment.

[0162] refer to Figures 16 to 19 , the COF module 2000 can be bent at least three times. For example, referring to Figures 16 to 18 , the COF module 2000 may be bent three times. That is, the COF module 2000 may include a first bending area BA1, a second bending area BA2, and a third bending area BA3.

[0163] Alternatively, refer to Figure 19 , the COF module 2000 may be bent four times. That is, the COF module 2000 may include a first bending area BA1, a second bending area BA2, a third bending area BA3, and a fourth bending area BA4.

[0164] Specifically, the COF module 2000 is bent in the first and third isolation regions IA1 and IA3. For example, the COF module is bent twice in the first isolation region IA1 and once in the third isolation region IA3. Furthermore, the COF module is not bent in the second isolation region IA2 where the through-holes are provided.

[0165] Therefore, when the COF module 2000 is bent, the through hole can be prevented from being deformed. In addition, since the COF module 2000 is bent in the first isolation area IA1, the size of the bezel area in the display panel connected to the COF module can be reduced.

[0166] In addition, reference Figures 16 to 19 , the first separation area IA1 and the third separation area IA3 may be curved with the same or different curvatures. Figure 18 , the first and third separation areas IA1 and IA3 may be curved with different curvatures.

[0167] The flexible circuit board according to the embodiment may form a COF module by mounting a chip (CH) on the chip mounting area CHA and cutting the cutting lines CL.

[0168] The COF module 2000 is positioned between the display panel 4000 and the circuit board 3000 and may connect electrical signals.

[0169] refer to Figure 13 According to an embodiment, one end of the COF module 2000 is connected to the display panel 4000. In addition, the other end opposite to the one end is connected to the circuit board 3000. For example, the display panel 4000 is provided on one surface of the COF module 2000. In addition, the circuit board 3000 may be provided on the other surface of the COF module 2000 opposite to the one surface. However, the embodiment is not limited thereto. The display panel 4000 and the circuit board 3000 may be provided on the same surface of the COF module 2000.

[0170] The COF module 2000 includes a flexible substrate, and thus the COF module 2000 can have either a rigid form or a curved form between the display panel 3000 and the circuit board 4000 .

[0171] The COF module 2000 can connect the display panel 4000 and the circuit board 3000, which are arranged opposite each other, in a curved form. This reduces the thickness of the electronic device and increases design freedom. Furthermore, the COF module 2000, which includes a flexible substrate, prevents wire breakage even when bent. This improves the reliability of the electronic device.

[0172] In addition, since the COF module 2000 is bent in the first isolation area IA1, the bezel area of ​​the display panel 4000 can be reduced. In addition, since the COF module 2000 is not bent in the second isolation area IA1, deformation of the through hole can be prevented.

[0173] Since the COF module is flexible, the COF module can be used in various electronic devices.

[0174] For example, reference Figure 20 The COF module can be applied to a curved flexible touch window. Therefore, a touch device including the COF module can be a flexible touch device.

[0175] refer to Figure 21 The COF module can be applied to various wearable touch devices including curved displays, thus making the wearable touch devices thinner or lighter.

[0176] refer to Figure 22 , COF modules can be applied to various electronic devices with display parts, such as TVs, monitors and notebook computers.

[0177] The features, structures, and effects described in the above embodiments are included in at least one embodiment, but are not limited to one embodiment. In addition, a person skilled in the art may combine or modify the features, structures, effects, etc. described in each embodiment to be equivalent to other embodiments. Therefore, it should be understood that the contents related to such combinations and modifications are included in the scope of the embodiments.

[0178] The above description focuses on the embodiments, but it is merely illustrative and not intended to limit the embodiments. Those skilled in the art will appreciate that various modifications and applications not described above may be made without departing from the essential features of the embodiments. For example, each component specifically shown in the embodiments may be modified and implemented. Furthermore, it should be understood that differences associated with such modifications and applications are within the scope of the embodiments as defined in the appended claims.

Claims

1. A flexible circuit board, comprising: a substrate comprising a first surface and a second surface opposite to the first surface; a first circuit pattern disposed on the first surface; a second circuit pattern disposed on the first surface and the second surface; a third circuit pattern, disposed on the first surface and the second surface; a first protective layer, disposed on the first surface; as well as a second protective layer disposed on the second surface, wherein the chip mounting area is defined on the first surface, The first circuit pattern includes: a first pad portion connected to the chip on the chip mounting area; a second pad portion connected to an external printed circuit board; and a first wiring portion connected to the first pad portion and the second pad portion. The second circuit pattern includes: a third pad portion connected to the chip; a fourth pad portion connected to an external display panel; and a second wiring portion connected to the third pad portion and the fourth pad portion. The third circuit pattern includes: a fifth pad portion connected to the chip; a sixth pad portion connected to the display panel; and a third wiring portion connected to the fifth pad portion and the sixth pad portion. wherein the second circuit pattern includes a first through hole connecting a second wiring portion on the first surface and a second wiring portion on the second surface, wherein a first length and a second length are defined in the second wiring portion, the first length being the distance from the end of the fourth pad portion to the first through hole closest to the fourth pad portion, and the second length being the length of the fourth pad portion; and Wherein, the first length is longer than the second length.

2. The flexible circuit board according to claim 1, wherein: The first length is 1.5 to 10 times the second length.

3. The flexible circuit board according to claim 1, wherein: A third length is defined in the second circuit pattern, the third length being a length from the first through hole closest to the fourth pad portion to the first through hole farthest from the fourth pad portion, and The first length is 0.3 to 0.8 times the third length.

4. The flexible circuit board according to claim 1, wherein The substrate in which cutting lines are defined, wherein a fourth length is defined, the fourth length being the length from the first through hole farthest from the fourth pad portion to the cutting line, and The first length is 1.5 to 10 times the fourth length.

5. The flexible circuit board according to claim 1, wherein The first length is 15 to 35 times the length of the first through hole.

6. The flexible circuit board according to claim 1, wherein The first length is 0.1 mm to 4 mm.

7. The flexible circuit board according to claim 1, wherein: The second length is 0.5 mm to 1 mm, Wherein, the third length is 1 mm to 4 mm, and Wherein, the fourth length is 0.15 mm to 0.6 mm.

8. The flexible circuit board according to claim 1, wherein: The substrate is defined in a cutting line and includes: a first separation area defined as an area between the fourth pad portion and a first through hole closest to the fourth pad portion; a second separation area defined as an area between the first through hole closest to the fourth pad portion and the cutting line; and a third separation area defined as an area between the sixth pad portion and the chip mounting area, and At least one of the first separation region and the second separation region is curved.

9. The flexible circuit board according to claim 8, wherein: The first separation region and the third separation region are curved, and Wherein, the first separation area is bent at least once.

10. The flexible circuit board according to claim 8, wherein: The second separation region is not curved.

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