KR102417789B1 - Flexible display device - Google Patents

Abstract

Disclosed herein is a flexible film. The flexible film may include a metal layer disposed in two or more layers; a first test line extending through at least one or more of the metal layers; The first test pad may include a first test pad connected to the first test line and positioned only on one side of a first side connected to the display panel and a second side opposite to the first side.

Description

Flexible display device {FLEXIBLE DISPLAY DEVICE}

The present specification relates to a flexible display device and a flexible circuit board used therein.

A video display device that implements various information on a screen is a key technology in the information and communication era, and is developing in the direction of thinner, lighter, more portable and high-performance. Accordingly, an organic light emitting display device that displays an image by controlling the amount of light emitted from the organic light emitting diode is in the spotlight.

The organic light emitting device is a self-luminous device using a thin light emitting layer between electrodes, and has an advantage that it can be thinned. A typical organic light emitting display device has a structure in which a pixel driving circuit and an organic light emitting device are formed on a substrate, and an image is displayed while light emitted from the organic light emitting device passes through a substrate or a barrier layer.

Since the organic light emitting display device is implemented without a separate light source device, it is easy to be implemented as a flexible display device. In this case, a flexible material such as plastic or metal foil is used as a substrate of the organic light emitting display device.

Driving circuits (eg, drive ICs) of the display device are connected to data lines (or signal lines) or scan lines (or gate lines) to drive pixels. The source drive IC supplies a data signal to the data lines, and the gate drive IC sequentially supplies a scan signal (or gate pulse) synchronized with the data signal to the scan lines. As a method of mounting such a driving circuit on a display device, a method of bonding a flexible substrate on which a circuit chip is mounted to a display panel, a method of directly bonding a circuit chip to the substrate, and the like are known. Meanwhile, when an organic light emitting display device is implemented as a flexible display device, research is being conducted to bend or bend various parts of the display device using its flexible properties. These studies are mainly conducted for new design and UI/UX, and in some cases, such studies are also conducted to reduce the area of the corner of the display device.

An object of the present specification is to propose a flexible circuit board and a display device including the same. The tasks of the present specification are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

A flexible film is provided according to an embodiment of the present specification. The flexible film may include a metal layer disposed in two or more layers; a first test line extending through at least one or more of the metal layers; The first test pad may include a first test pad connected to the first test line and positioned only on one side of a first side connected to the display panel and a second side opposite to the first side.

According to another embodiment of the present specification, a flexible display device is provided. The flexible display may include a first portion having an organic light emitting diode disposed on a first surface, a second portion outside the first portion, and an opposite side of the first surface between the first portion and the second portion a flexible base layer having a curved section bent toward a second surface; a flexible circuit board adhered to the second part; a protective coating layer covering the bending section, wherein the flexible circuit board includes a first test line extending in a lateral direction for bonding to another circuit board through at least one of metal layers arranged in two or more layers; An end of the first test line may be sealed with a protective material.

Specific details of other embodiments are included in the detailed description and drawings.

The flexible circuit board according to the embodiment of the present specification may have a structure that is easy to prevent corrosion of metal wires while not having a problem in product inspection. Further, embodiments of the present specification provide a display device with improved reliability. can provide Effects according to the embodiments of the present specification are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 illustrates an exemplary flexible display device that may be included in an electronic device.
2A and 2B illustrate an outer arrangement of a flexible display device according to an exemplary embodiment of the present specification.
3A to 3C are views illustrating a flexible film used in a flexible display device according to an exemplary embodiment of the present specification.
4A to 4C are views illustrating a flexible film used in a flexible display device according to another exemplary embodiment of the present specification.

Advantages and features of the present specification, and a method for achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present specification are exemplary, and thus the present specification is not limited to the illustrated matters. Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, cases including the plural are included unless otherwise explicitly stated. In interpreting the components, it is construed as including an error range even if there is no separate explicit description.

In the case of a description of the positional relationship, for example, when the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., 'right' Alternatively, one or more other parts may be positioned between two parts unless 'directly' is used. Reference to a device or layer “on” another device or layer includes any intervening layer or other device directly on or in the middle of the other device or layer. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may be interposed between each component. It should be understood that each component may be “interposed” or “connected”, “coupled” or “connected” through another component.

Although first, second, etc. are used to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the spirit of the present invention.

The size and thickness of each component shown in the drawings are illustrated for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated component. Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates an exemplary flexible display device that may be included in an electronic device.

The flexible display device refers to a display device to which flexibility is imparted, and includes a bendable display device, a rollable display device, an unbreakable display device, and a foldable display device. It can be used in the same meaning as a foldable display device. Referring to FIG. 1 , the flexible display device 100 includes at least one active area, and an array of pixels is formed in the display area. One or more inactive areas may be disposed around the display area. That is, the non-display area may be adjacent to one or more side surfaces of the display area. In FIG. 1 , the non-display area surrounds a rectangular display area. However, the shape of the display area and the shape/arrangement of the non-display area adjacent to the display area are not limited to the example illustrated in FIG. 1 . The display area and the non-display area may have a shape suitable for designing an electronic device on which the flexible display device 100 is mounted. Exemplary shapes of the display area are pentagonal, hexagonal, circular, oval, and the like.

Each pixel in the display area may be associated with a pixel circuit. The pixel circuit may include one or more switching transistors and one or more driving transistors on a backplane. Each pixel circuit may be electrically connected to a gate line and a data line to communicate with one or more driving circuits such as a gate driver and a data driver located in the non-display area.

As shown in FIG. 1 , the driving circuit may be implemented as a thin film transistor (TFT) in the non-display area. Such a driving circuit may be referred to as a gate-in-panel (GIP). In addition, some components such as data driver IC are mounted on a separate circuit board and use circuit films such as flexible printed circuit board (FPCB), chip-on-film (COF), and tape-carrier-package (TCP). Thus, it may be coupled to a connection interface (pad/bump, pin, etc.) disposed in the non-display area. The non-display area may be bent together with the connection interface, so that the printed circuit (COF, PCB, etc.) may be positioned behind the flexible display device 100 .

The flexible display device 100 may include various additional elements for generating various signals or driving pixels in the display area. Additional elements for driving the pixel may include an inverter circuit, a multiplexer, an electrostatic discharge circuit, and the like. The flexible display device 100 may also include additional elements related to functions other than driving pixels. For example, the flexible display device 100 may include additional elements that provide a touch sensing function, a user authentication function (eg, fingerprint recognition), a multi-level pressure sensing function, a tactile feedback function, and the like. . The above-mentioned additional elements may be located in the non-display area and/or in an external circuit connected to the connection interface.

Several portions of the flexible display device 100 may be bent along the curved line BL. The curved line BL may extend horizontally (eg, in the X direction of FIG. 1 ), vertically (eg, in the Y direction of FIG. 1 ), or diagonally. Based on the design being made, it can be bent in any combination of horizontal, vertical and diagonal directions.

As mentioned, one or more edges of the flexible display device 100 may be bent away from a central portion 101 along the curved line BL. Although the curved line BL is illustrated to be positioned close to the edge of the flexible display device 100 , the curved line BL extends across the central portion 101 or the flexible display device 100 . may extend diagonally at one or more corners of Such a structure may enable the flexible display device 100 to be a foldable display device or a display device in which displays are displayed on both sides of the display device.

Since one or more portions of the flexible display device 100 may be bent, the flexible display device 100 may be defined as a substantially flat portion and a curved portion. A portion of the flexible display device 100 may be referred to as a substantially flat central portion 101 . A portion of the flexible display device 100 is bent at a predetermined angle, and this portion may be referred to as a bent portion 102 . The bent portion 102 includes a bent section that is actually bent to a predetermined radius of curvature. The term “substantially flat” includes portions that are not perfectly flat. In other words, the term “substantially flat portion” may mean a portion having a smaller curvature than an adjacent section.

According to the position of the curved line BL, a portion on one side of the curved line is positioned toward the center of the flexible display device 100 , while a portion on the other side of the curved line is positioned toward the edge of the flexible display device 100 . . A portion lying toward the center of the flexible display device 100 may be referred to as a center portion, and a portion lying toward a corner of the flexible display device 100 may be referred to as a corner portion. Although not always, a central portion of the flexible display device 100 may be substantially flat, and a corner portion may be a curved portion. It should be mentioned that the substantially flat portions may also be located in the corner portions. In addition, in some shapes of the flexible display device 100 , the curved section may be disposed between two substantially flat portions.

As mentioned above, when the non-display area is bent, the non-display area is not visible from the front side of the display device or is visible only minimally. A portion of the non-display area visible from the front side of the display device may be covered with a bezel. The bezel may be formed as a stand-alone structure, or as a housing or other suitable element. Some of the non-display area visible from the front of the display may be hidden under an opaque mask layer such as black ink (eg, a polymer filled with carbon black). Such an opaque mask layer may be provided on various layers (such as a touch sensor layer, a polarization layer, and a cover layer) included in the flexible display device 100 .

In FIG. 1 , the central portion 101 is substantially flat, and the curved portion 102 is illustrated as being at a corner of the flexible display device 100 . One or more flexure portions 102 may be bent outwardly from the central portion 101 with a bend angle θ and a bend radius R with respect to the flexure axis. The size of each of the curved portions 102 need not be the same. That is, the length from the curved line BL to the outer edge of the display device in each curved portion 102 may be different from each other. Further, the angle of flexion θ around the flexion axis and the radius of curvature R from the flexion axis may be different for each flexure portion 102 .

2A and 2B are cross-sectional views illustrating the arrangement of an outer portion of a flexible display device according to an exemplary embodiment of the present specification.

2A and 2B illustrate a structure in which a portion of an outer portion of a flexible display device is bent (folded). The flexible display device may include a base layer 106 , a support layer 108 , a polarization layer 110 , a protective coating layer 132 , and a flexible circuit board 200 . An organic light emitting diode and an encapsulation layer 104 may be sequentially disposed on the base layer 106 , and a polarization layer 110 may be disposed on the encapsulation layer 104 . A cover layer 114 may be disposed on the polarization layer 110 . A support layer 108 may be positioned under the base layer 106 .

When the base layer 106 is made of plastic, it may be referred to as a plastic film or a plastic substrate. For example, the base layer 106 may be in the form of a film including one selected from the group consisting of a polyimide-based polymer, a polyester-based polymer, a silicone-based polymer, an acrylic polymer, a polyolefin-based polymer, and a copolymer thereof. Among these materials, polyimide is widely used as a plastic substrate because it can be applied to high-temperature processes and can be coated.

The base layer 106 of the flexible display device may include a first portion 101 and a second portion 102 as shown in FIG. 2 . The first portion 101 may correspond to the central portion of FIG. 1 , and the second portion 102 may correspond to the curved portion of FIG. 1 . Although the second portion 102 is illustrated as extending outwardly of the first portion 101 in FIG. 2 , the spirit of the present specification is not limited thereto. In the first portion 101 , an organic light emitting device, a polarizing layer 110 , and the like are disposed. In this case, the organic light emitting diode, the polarization layer 110, and the like are disposed on the first surface (top surface) of the first part 101 . Meanwhile, the second part 102 may be a non-display area outside the first part, and may be bent toward a second surface (a lower surface, opposite to the first surface) of the first part 101 . part (bending section 102b). In this case, the second part 102 may be provided to extend outwardly of the first part 101 . The second portion 102 may include a bent section 102b that is bent to a predetermined curvature and a flat section that is not bent (a section supported by the support layer 108 ).

A backplane of the flexible display device 100 is implemented on the base layer 106 . In some embodiments, the backplane of the flexible display device 100 is implemented together with a TFT using a low temperature poly silicon (LTPS) semiconductor layer as an active layer. In one example, the pixel circuit and driving circuits (eg, GIPs) on the base layer 106 may be implemented as NMOS LTPS TFTs. In another example, the backplane of the flexible display device 100 may be implemented as a combination of an NMOS LTPS TFT and a PMOS LTPS TFT. For example, the driving circuit (eg, GIP) on the base layer 106 may include one or more CMOS circuits in order to reduce the number of wires for controlling a scan signal on a gate line.

In some embodiments, the flexible display device 100 may employ various types of TFTs to implement driving circuits in a pixel circuit in a non-display area and/or a display area. That is, to implement the backplane of the flexible display device 100 , a combination of an oxide semiconductor TFT and an LTPS TFT may be used. In the backplane, the type of TFT may be selected according to operating conditions and/or TFT requirements in the relevant circuit.

An organic light emitting device (OLED) layer is disposed on the TFT backplane. The organic light emitting device layer includes a plurality of OLED devices. The OLED device may have a form in which a first electrode, an organic light emitting layer, and a second electrode are sequentially disposed. That is, the organic light emitting diode may include a first electrode electrically connected to a driving TFT, an organic light emitting layer positioned on the first electrode, and a second electrode positioned on the organic light emitting layer. The OLED device is controlled by a pixel circuit and a driving circuit implemented on the base layer 106 , and another external driving circuit connected to a connection interface on the base layer 106 . The OLED layer may include an organic light emitting material layer emitting light of a specific color (eg, red, green, blue). In some embodiments, the organic light emitting material layer may have a stacked structure capable of emitting white light (essentially a combination of light of several colors).

The encapsulation layer 104 is provided to protect the organic light emitting device layer from air and moisture. The encapsulation layer 104 may include several layers of material to reduce the penetration of air and moisture. In some embodiments, the encapsulation layer 104 may be provided in a thin film shape (eg, a barrier film).

A polarization layer 110 may be included in the flexible display device 100 to control display characteristics (eg, external light reflection, color accuracy, luminance, etc.). Also, the cover layer 114 may be used to protect the flexible display device 100 .

An electrode for sensing a user's touch input may be formed on at least one surface of the cover layer 114 , the polarization layer 110 and/or the encapsulation layer 104 . If necessary, an independent layer provided with touch sensing electrodes and/or other components related to touch input sensing may be provided in the flexible display device 100 . For easier bending and improved reliability of the flexible display device 100 , the configuration of components in the curved portion 102 may be different from that of the central portion 101 . That is, some components present in the central portion 101 are not disposed in the curved portion 102 or are provided in different thicknesses. For example, the support layer 108 , the polarization layer 110 , the color filter layer, and/or other components that interfere with the bending of the flexible display device 100 may not be present in the curved portion 102 . If the flexure portion 102 is not visible or accessible to the user, then these components are not required.

In order to increase strength and/or rigidity in a specific portion of the flexible display device 100 , one or more support layers 108 may be provided under the base layer 106 . For example, the support layer 108 may be provided on the underside of the central portion 101 . The support layer 108 may not be provided in a bending section requiring greater flexibility. The support layer 108 may be provided on the curved portion 102 located below the central portion 101 . Increasing the strength of a specific part helps in accurately configuring and arranging various parts in the flexible display device 100 . When the base layer 106 has greater elasticity than the support layer 108 , the support layer 108 may contribute to suppressing occurrence of cracks in the base layer 106 .

The protective coating layer 132 , which may also be referred to as a micro-coating layer, may be provided on the conductive wire and/or the wiring structure in the bent portion to protect the conductive wire in the bent section. The protective coating layer 132 may be coated on the curved portion to a thickness determined to adjust the neutral plane of the flexible display device 100 in the curved portion. More specifically, the thickness added to the protective coating layer 132 at the bent portion may move the plane of the conductor and/or wiring structure closer to a neutral plane. The protective coating layer 132 has sufficient flexibility to be used in a curved portion of the flexible display device 100 . In addition, the protective coating layer 132 is preferably a material that cures with low energy within a limited time so as not to damage the components underneath it during the curing process. The protective coating layer 132 may be formed of a light (eg, UV light, visible light, etc.) curable acrylic resin. In order to inhibit the penetration of moisture through the protective coating layer 132 , one or more hygroscopic materials (getters) may be mixed into the protective coating layer 132 . The protective coating layer 132 covers at least a portion of the first surface (top surface) of the second portion 102 .

The flexible display device may further include a flexible circuit board 200 connected to the second part. A driver IC chip may be mounted on the flexible circuit board 200 . The flexible circuit board may be a chip on film (COF) or a tape carrier package (TCP). The flexible board is also connected to another circuit board 500 that primarily provides image information/control information and the like.

When there is the flexible circuit board 200 , the protective coating layer 132 may cover between the flexible circuit board 200 from the outer side of the polarizing layer 110 , and the protective coating layer 132 . ) may cover a portion of the upper edge surface of the flexible circuit board 200 .

A portion (generally the portion shown in FIG. 1 ) excluding ancillary components such as the flexible circuit board 200 and another circuit board 500 may be referred to as a display panel.

3A to 3C are views illustrating a flexible film used in a flexible display device according to an exemplary embodiment of the present specification.

The flexible film 300 may be a flexible circuit board capable of accommodating a circuit chip and/or various components for controlling pixels of a display area and various driving circuits. The higher the resolution of the image expressed by the display device, the more sophisticated the integrated circuit is used. In order to display such high-resolution image information, data lines/scan lines of the display panel are increased, and the structure of a circuit (eg, a driving IC) that controls it is also complicated, so that more wires are connected to the circuit. As the number of wires increases, the flexible circuit board 300 requires more electrodes. As one method of solving this, in order to facilitate the electrode/wire design of the flexible circuit board 300, a metal layer having a multi-layer structure may be used. According to this method, the arrangement of wires and electrodes can be more freely do.

3A and 3B are plan views illustrating a first surface (eg, top surface) and a second surface (eg, bottom surface) of an exemplary flexible film 300 , respectively. Here, the first surface may be a surface on which a circuit chip (eg, a D-IC) is mounted, and the second surface may be a surface opposite to the first surface. Meanwhile, FIG. 3C is a cross-sectional view illustrating an exemplary flexible film 300 attached to a display device.

The flexible film 300 may include a thin film substrate 310, metal layers 321 and 322 arranged in two or more layers, a protective layer 311, a contact hole C, connection parts 350 and 360, etc. have.

The thin film substrate 310 may include polyimide, acrylic, polyether nitrile, polyethersulfone, and polyethylene terephthale having excellent coefficient of thermal expansion (CTE) and durability. It may be made of a synthetic resin such as polyethylene terephthalate or polyethylene naphthalate. The thin film substrate 310 may be a multi-layered film including an insulating function, or a film coated with a silicon-based or nitride-based material to minimize parasitic or static current. The thin film substrate 310 has a flexible property.

The flexible film 300 may include a first metal layer 321 and a second metal layer 322 patterned on both surfaces of the thin film substrate 310 as shown in FIG. 3C . The first metal layer 321 and the second metal layer 322 may be disposed on different layers of the flexible circuit board 300 , and this may be referred to as a multi-layer structure. Since the metal layers 321 and 322 have to transmit electrical signals and currents, they may be formed of a metal (eg, copper, etc.) having a relatively low electrical resistance. However, metals are prone to oxidation when exposed to air. When the metal is oxidized, the electrical resistance increases or changes, noise may be added to the electrical signal that drives the image, and even if the oxidation is severe, it may become insulator and the electrical connection may be broken. Accordingly, the metal layers 321 and 322 may be covered with a protective layer 311 . The protective layer 311 may be made of a permanent coating material such as solder resist.

Wires (electrodes) formed through the metal layers arranged in multiple layers may be insulated from each other and may be connected to each other through the contact hole C if necessary. Wires/electrodes may have interfaces (electrodes, pads, pins, etc.) for electrical connection with other parts at their ends.

The flexible film 300 is provided with a first connector 360 for connecting to the display panel and a second connector 350 for connecting to another circuit board. The connection units 350 and 360 provide paths for exchanging various electrical signals with other circuit boards (eg, system boards) and display panels. The connecting portions 350 and 360 may be electrodes on which electric wires are extended, and for connection with other portions, a surface area may be formed to be larger than that of other portions of the electric wires.

The flexible film 300 may be electrically connected to the display panel through the first connection part 360 . For example, a display panel (eg, a silver interface terminal (eg, a pad 106P)) is provided, and the interface terminal 106P and the first connection part 360 are conductive balls included in a conductive adhesive (eg, ACF). The second connection part 350 is a connector type component and may be connected to another circuit board through a connector film.

The flexible film 300 may have an area PA for accommodating the circuit chip. The circuit chip may be a drive IC that drives pixels of the display panel. The circuit chip may have a built-in hardware/software that processes data for displaying an image by driving a pixel. The circuit chip may be protected by an insulating tape or the like, whereby noise due to electrical influence may be minimized.

After the flexible film 300 is manufactured, various tests (function test, wiring test, etc.) are performed. Accordingly, a test pad and a test line for the test are provided on the flexible film. 3A and 3B show these test pads TP1 and TP2 and test lines TL1 and TL2. The test pads TP1 and TP2 and the test lines TL1 and TL2 may be classified according to a type of a transmitted signal. For example, it may be classified into test lines/pads connected to a wire through which a signal related to the gate driver is transmitted, and test lines/pads connected to a wire through which a signal related to the data driver is transmitted.

3A and 3B illustrate a first test pad TP1 and a test line TL1 , and a second test pad TP2 and a second test line TL2 . The first test line TL1 extends in the vertical direction through at least one of the two or more metal layers provided on the flexible film 300 . Here, the vertical direction refers to a direction from the center of the flexible film 300 toward the outside. The first test pad TP1 is connected to the first test line TL1 and is positioned on both sides of the flexible film.

Similarly, the second test line TL2 extends in the vertical direction through at least one of the two or more metal layers provided on the flexible film 300 . The second test pad TP2 is connected to the second test line TL2 and is positioned on both sides of the flexible film.

The first and second test pads TP1 and TP2/test lines TL1 and TL2 are used to inspect the connection state of the wiring and the quality of the transmitted signal. In the flexible film 300 that has been inspected, a portion of the outer region may be cut off for convenience of adhesion to the display panel. (punching, trimming, chamfering, etc.) PL1 and PL2 exemplarily show such cut lines. Since the test pads TP1 and TP2 are no longer used, they are cut together at this time. In this process, several metal layers including the test line are exposed to the outside through the cut surface.

The flexible film in which the outer part is arranged may be attached to the display panel as shown in FIG. 3C . In this case, the first connection part 350 of the flexible film may be electrically connected to the interface terminal 106P of the display panel through the conductive adhesive 150 . However, exposed metal layers may exist on both sides of the flexible film. Metals exposed to air should be covered with a protective material as corrosion is likely to occur. In the attachment as shown in FIG. 3C , the right end (far from the display panel) is not difficult to be finished with the same material as the protective layer 311 . However, since the left end (closer to the display panel) is covered with the protective coating layer 132 , it is difficult to separately finish it. As described above, since the protective coating layer 132 is a material having sufficient flexibility to be used in the bent portion, moisture resistance is not very high. Accordingly, moisture penetration through the protective coating layer 132 may affect the metal exposed at the end of the flexible film. Furthermore, in the flexible film, the conductors connected to the gate driver and the test lines connected thereto (eg, TL1) pass signals with relatively high voltages (or potential differences). It is more susceptible to corrosion due to the high potential difference of Corrosion, once generated in the metal layer, continues to propagate, and eventually the reliability of various signals transmitted through the flexible film is lowered, and thus the quality of the entire display device is also deteriorated. Recognizing this problem, the inventors devised an improved wiring arrangement of the flexible film. In addition, a flexible display device to which the flexible film is applied has been derived. An improved flexible film is described below.

4A to 4C are views illustrating a flexible film used in a flexible display device according to another exemplary embodiment of the present specification.

The flexible film 400 may be a flexible circuit board capable of accommodating a circuit chip and/or various components for controlling pixels of a display area and various driving circuits. The flexible film 400 may include a thin film substrate 410, metal layers 421 and 422 disposed in two or more layers, a protective layer 411, a contact hole C, connection portions 450 and 460, and the like. have. The flexible film 400 is the same as the flexible film 300 described with reference to FIGS. 3A to 3C except for a structure for preventing corrosion of side metals, and thus a redundant description of the components will be omitted. The flexible film 400 is different from the flexible film 300 described with reference to FIGS. 3A to 3C in the arrangement of the test pad.

4A and 4B are plan views illustrating a first surface (eg, top surface) and a second surface (eg, bottom surface) of an exemplary flexible film 400 , respectively. Here, the first surface may be a surface on which a circuit chip (eg, a D-IC) is mounted, and the second surface may be a surface opposite to the first surface. Meanwhile, FIG. 4C is a cross-sectional view illustrating an exemplary flexible film 400 attached to a display device.

In the flexible film 400 , a test wire connected to a path through which a signal having a large potential difference (a voltage swing width of the signal itself or a voltage difference with an adjacent wire) passes and a test pad connected thereto are disposed on only one side. Referring to the drawings, the flexible film 400 includes a first test pad TP1 and a test line TL1 , and a second test pad TP2 and a second test line TL2 . Here, the first test line TL1 may be a line connected to a path transmitting a signal to a gate driver (eg, GIP), and the second test line TL2 may be a line connected to a path transmitting a data signal. That is, the first test line TL1 may be a test line connected to a path through which the signal having a large potential difference passes. Therefore, the potential difference of the signal transmitted through the first test line TL1 is greater than the potential difference of the signal transmitted through the second test line TL2 , and the possibility of corrosion due to the above-described exposure is also increased in the first test line TL1 . this is higher

The first test line TL1 extends through at least one of the two or more metal layers provided on the flexible film 400 . The first test pad TP1 is connected to the first test line TL1 and is positioned on only one of the first side connected to the display panel and the second side opposite to the first side. 3A and 3B show that the first test pad TP1 is on the second side.

Similarly, the second test line TL2 extends in the vertical direction through at least one of the two or more metal layers provided on the flexible film 300 . The second test pad TP2 is connected to the second test line TL2 and is positioned on at least one of a first side connected to the display panel and a second side opposite to the first side. 3A and 3B show that the second test pad TP2 is located on the first side and on the second side, the second test pad TP2 may be located only on the side where the first test pad TP1 is located. can

The flexible film 400 includes a circuit chip area PA on which a driving circuit chip is placed. The first test line TL1 extends from the circuit chip area PA to the first test pad TP1 . The second test line TL2 extends from the circuit chip area PA to the second test pad TP2 .

The first test pad TP1 and the second test pad TP2 may be positioned on the same surface. Although the drawing shows that the first test pad TP1 and the second test pad TP2 are co-located on the second surface, on the contrary, the first test pad TP1 and the second test pad TP2 are It may be located together on the first surface.

The flexible film 400 may include a first connector 460 provided on the first side to be connected to the display panel; and a second connection part 450 provided on the second side to be connected to another circuit board. The connection units 450 and 460 provide paths for exchanging various electrical signals with other circuit boards (eg, a system board) and a display panel. The first connection part 460 and the second connection part 450 may be connected to a display panel and/or another circuit through at least one of anisotropic conductive film (ACF), anisotropic conductive adhesive (ACA), and anisotropic conductive paste (ACP). adhered to the substrate.

In the flexible film 400 that has been inspected, a portion of the outer region may be cut off for convenience of adhesion to the display panel. (punching, trimming, chamfering, etc.) PL1 and PL2 exemplarily show such cut lines. Since the test pads TP1 and TP2 are not used after the test, they are cut together at this time. The flexible film in which the outer part is arranged may be attached to the display panel as shown in FIG. 4C . In this case, the first connection part 350 of the flexible film may be electrically connected to the interface terminal 106P of the display panel through the conductive adhesive 150 . Referring to FIG. 4C , a flexible display device including a flexible base layer 106 , a flexible circuit board 400 , and a protective coating layer 132 can be seen. The flexible base layer 106 may include, as described with reference to FIGS. 1 and 2 , a first portion on which an organic light emitting diode is disposed on the first surface; a second portion outside the first portion; Between the first portion and the second portion, there is a curved section bent toward a second surface opposite to the first surface. The flexible circuit board 400 is adhered to the second part. The protective coating layer 132 covers the curved section.

The flexible circuit board 400 may include a first test line. The first test line may extend in a lateral direction to adhere to another circuit board through at least one of the metal layers arranged in two or more layers. Also, an end of the first test line may be sealed with a protective material 411 ′. The protective material 411 ′ may be made of the same material (eg, SR) as the protective layer 411 .

The flexible circuit board 400 may further include a second test line. The second test line may extend in a bending section direction and a lateral direction bonding to the other circuit board through at least one of the metal layers arranged in two or more layers. When the second test line extends in the bending section direction, an end of the second test line may be covered with the protective coating layer 132 .

An exposed metal layer may be present on at least one side surface of the flexible film 400 of FIGS. 4A to 4C . However, in the above embodiment, in the flexible film 400 , the test line TL1 connected to the signal line having a high potential difference may be exposed to the side for easy finishing. That is, when the first test line is exposed to the side that is easily covered with the protective material 411 ′ as shown in FIG. 4C , corrosion due to moisture permeation can be prevented even afterward.

In addition, even if the test line TL2 connected to the signal line with a low potential difference is exposed to a side that is difficult to finish, since the possibility of corrosion is low, only the cover with the protective coating layer 132 may provide sufficient protection. Of course, if the second test line is also exposed only from the same side as the first test line, it can be easily protected by the protective material 411 ′.

Through the above-described arrangement of the test line and the test pad, it is possible to manufacture the flexible film 400 that has no problem in product inspection and is easy to prevent corrosion of the metal layer in the future, which can lead to improved reliability of the display device. Although the embodiments of the present specification have been described in detail with reference to the accompanying drawings, the present specification is not necessarily limited to these embodiments, and various modifications may be made without departing from the technical spirit thereof. Therefore, the embodiments disclosed in the present specification are for explanation rather than limiting the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments. Each of the features of the various embodiments of the present invention may be partially or wholly combined or combined with each other, and may be technically variously linked and operated by those skilled in the art, and each of the embodiments may be implemented independently of each other or together in a related relationship. may be carried out. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

321, 322, 421, 422: metal layer
311, 411: protective layer
C: contact hole
350, 360, 450, 460: Connection
TL1, TL2: test line
TP1, TP2 : test pad

Claims (15)

a first portion disposed on a first surface, a second portion outside the first portion, and between the first portion and the second portion bent toward a second surface opposite the first surface a flexible base layer having a curved section;
a flexible circuit board adhered to the second part;
A protective coating layer covering the curved section,
The flexible circuit board,
a metal layer arranged in two or more layers;
a first test line extending in a lateral direction for bonding to another circuit board through at least one of the metal layers; and
a first test pad connected to the first test line and positioned on only one of a first side connected to the display panel and a second side opposite to the first side;
and an end of the first test line is sealed with a protective material. According to claim 1,
The flexible circuit board,
a circuit chip region on which the driving circuit chip is placed;
The first test line extends from the circuit chip region to the first test pad. According to claim 1,
The first test line is connected to a path through which a signal is transmitted to a gate driver. According to claim 1,
The flexible circuit board,
a second test line extending in a bending section direction and a lateral direction bonding to the other circuit board through at least one of the metal layers; and
and a second test pad connected to the second test line and positioned on at least one of a first side connected to the display panel and a second side opposite to the first side. 5. The method of claim 4,
and the second test line extends from a circuit chip region on which a driving circuit chip is placed to the second test pad. 5. The method of claim 4,
and the second test line is connected to a path through which a data signal is transmitted. 5. The method of claim 4,
and the first test pad and the second test pad are positioned on the same surface. 8. The method of claim 7,
The first test pad is located on the second side, and the second test pad is located on both the first side and the second side. 5. The method of claim 4,
and a potential difference of a signal transmitted through the first test line is greater than a potential difference of a signal transmitted through the second test line. According to claim 1,
a first connector provided on the first side to be connected to the display panel; and
The flexible display device of claim 1 , further comprising a second connector provided on the second side to be connected to another circuit board. delete delete 5. The method of claim 4,
An end of the second test line in the direction of the bending section is covered with the protective coating layer. According to claim 1,
The flexible circuit board,
a first connection part bonded to the second part; and
The flexible display device further comprising a second connector bonded to the other circuit board. 15. The method of claim 14,
The first connection part and the second connection part,
A flexible display device bonded to the second part and the other circuit board through at least one of an anisotropic conductive film (ACF), an anisotropic conductive adhesive (ACA), and an anisotropic conductive paste (ACP).

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