Touch sensor and display device including the same

A touch sensor includes a touch sensing region, a touch sensing electrode in the touch sensing region, a touch extending wire extended to the touch sensing electrode, a touch pad on an end of the touch extending wire, a flexible printed circuit board overlapping the touch pad, a flexible printed circuit pad on the flexible printed circuit board and facing the touch pad, and a conductive bonding member between the touch pad and the flexible printed circuit pad. The conductive bonding member is bonded to each of the touch pad and the flexible printed circuit pad. The touch pad includes a first touch pad layer made of a transparent metal oxide, and a second touch pad layer on the first touch pad layer. The second touch pad layer is made of a metal material. The conductive bonding member is bonded to the second touch pad layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0137995, filed Oct. 31, 2019, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Field

Some exemplary embodiments generally relate to a touch sensor and a display device including the same.

Discussion

A display device is a device for displaying an image, and may include a liquid crystal display (LCD), an organic light emitting diode (OLED) display, and the like. The display device may be used in various electronic devices, such as a mobile phone, a navigation device, a digital camera, an electronic book, a portable game machine, various terminals, etc. An input device for the electronic device may include a touch sensor for a user to contact (or otherwise interact with) a screen with a finger or a pen to input information. From among various sensing methods of touch sensors, a capacitive type for sensing a position where a change in capacitance caused by a contact is generated from two electrodes separated from each other is generally used. A touch pad of a touch sensor may be connected to a flexible printed circuit pad. It is also recognized that methods and devices for reducing the thickness of electronic devices and the size of bezels are being explored. Accordingly, the touch pad is becoming smaller. As the touch pad becomes smaller, an electrical connection to the flexible printed circuit pad may generate defects.

The above information disclosed in this section is only for understanding the background of the inventive concepts, and, therefore, may contain information that does not form prior art.

SUMMARY

Some aspects provide a touch sensor capable of allowing an electrical connection between a touch pad and a flexible printed circuit pad to be properly performed and more reliable.

Some aspects provide a display device including a touch sensor capable of allowing an electrical connection between a touch pad and a flexible printed circuit pad to be properly performed and more reliable.

According to some aspects, a touch sensor includes a touch sensing region, a touch sensing electrode in the touch sensing region, a touch extending wire extended to the touch sensing electrode, a touch pad on an end of the touch extending wire, a flexible printed circuit board overlapping the touch pad, a flexible printed circuit pad on the flexible printed circuit board and facing the touch pad, and a conductive bonding member between the touch pad and the flexible printed circuit pad. The conductive bonding member is bonded to each of the touch pad and the flexible printed circuit pad. The touch pad includes a first touch pad layer made of a transparent metal oxide, and a second touch pad layer on the first touch pad layer. The second touch pad layer is made of a metal material. The conductive bonding member is bonded to the second touch pad layer.

According to some aspects, a display device includes a substrate, a light-emitting device, an encapsulation structure, a touch sensing electrode, a touch extending wire, a touch pad, a flexible printed circuit board, a flexible printed circuit pad, and a conductive bonding member. The substrate includes a touch sensing region. The light-emitting device is on the substrate. The encapsulation structure is on the light-emitting device. The touch sensing electrode is in the touch sensing region on the encapsulation structure. The touch extending wire is extended to the touch sensing electrode. The touch pad is on an end of the touch extending wire. The flexible printed circuit board overlaps the touch pad. The flexible printed circuit pad is on the flexible printed circuit board and faces the touch pad. The conductive bonding member is between the touch pad and the flexible printed circuit pad. The conductive bonding member is bonded to each of the touch pad and the flexible printed circuit pad. The touch pad includes a first touch pad layer made of a transparent metal oxide, and a second touch pad layer on the first touch pad layer. The second touch pad layer is made of a metal material. The conductive bonding member is bonded to the second touch pad layer.

According to various exemplary embodiments, the touch pad and the flexible printed circuit pad may be bonded with a conductive ball so that an electrical connection between the touch pad and the flexible printed circuit pad may be stably formed/performed.

DETAILED DESCRIPTION OF SOME EXEMPLARY EMBODIMENTS

Unless otherwise specified, the illustrated exemplary embodiments are to be understood as providing exemplary features of varying detail of some exemplary embodiments. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions, aspects, etc. (hereinafter individually or collectively referred to as an “element” or “elements”), of the various illustrations may be otherwise combined, separated, interchanged, and/or rearranged without departing from the inventive concepts.

When an element, such as a layer, is referred to as being “on,” “connected to,” or “coupled to” another element, it may be directly on, connected to, or coupled to the other element or intervening elements may be present. When, however, an element is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element, there are no intervening elements present. Other terms and/or phrases used to describe a relationship between elements should be interpreted in a like fashion, e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” “on” versus “directly on,” etc. Further, the term “connected” may refer to physical, electrical, and/or fluid connection. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be construed as X only, Y only, Z only, or any combination of two or more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,” “above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), and the like, may be used herein for descriptive purposes, and, thereby, to describe one element's relationship to another element(s) as illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of an apparatus in use, operation, and/or manufacture in addition to the orientation depicted in the drawings. For example, if the apparatus in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and, as such, the spatially relative descriptors used herein interpreted accordingly. Additionally, the phrase “on a plane” means viewing an object portion from the top, and the phrase “on a cross-section” means viewing a cross-section of which an object portion is vertically cut from the side.

Various exemplary embodiments are described herein with reference to sectional views, isometric views, perspective views, plan views, and/or exploded illustrations that are schematic illustrations of idealized exemplary embodiments and/or intermediate structures. As such, variations from the shapes of the illustrations as a result of, for example, manufacturing techniques and/or tolerances, are to be expected. Thus, exemplary embodiments disclosed herein should not be construed as limited to the particular illustrated shapes of regions, but are to include deviations in shapes that result from, for instance, manufacturing. To this end, regions illustrated in the drawings may be schematic in nature and shapes of these regions may not reflect the actual shapes of regions of a device, and, as such, are not intended to be limiting.

Hereinafter, various exemplary embodiments will be explained in detail with reference to the accompanying drawings.

A display device according to some exemplary embodiments will now be described with reference toFIGS. 1 and 2.

FIG. 1shows a top plan view of a display device according to some exemplary embodiments.FIG. 2shows a cross-sectional view with respect to sectional line II-II ofFIG. 1according to some exemplary embodiments.

As shown inFIGS. 1 and 2, the display device includes a display panel100and a touch sensor200provided on the display panel100.

The display device includes a display area DA and a peripheral area PA provided outside the display area DA. The display area DA represents a region for displaying an image according to on/off operations of a plurality of pixels included in the display panel100. The peripheral area PA represents a region in which a driving circuit for driving a plurality of pixels of the display area DA is mounted or formed. The display device according to an exemplary embodiment may further include a touch sensing region TA. The touch sensing region TA represents a region for sensing a touch (or touch interaction) by the touch sensor200. The touch sensing region TA may correspond to the display area DA. This, however, is an example, and the touch sensing region TA may not correspond to the display area DA. For example, the touch sensing region TA may be narrower and/or wider than the display area DA.

The display panel100may be flexible, stretchable, foldable, bendable, or rollable, embodiments are not limited thereto. For instance, the display panel100may be bent on a border between the display area DA and the peripheral area PA. The peripheral area PA may be bent from the display area DA and may be provided on a rear side of the display area DA. This, however, is an example, and the peripheral area PA may have various modifiable positions.

The display panel100includes a substrate110, a light-emitting device120provided on the substrate110, and an encapsulation substrate130provided on the light-emitting device120.

The substrate110may be an insulating substrate made of at least one of glass, quartz, ceramic, and plastic, or it may be a metallic substrate made of stainless steel.

A plurality of pixels may be disposed in formation (e.g., a matrix formation) on the substrate110, and the pixels may receive an image signal and may output an image. The light-emitting device120may be provided in the display area DA, and it may be provided for each pixel. For instance, the display panel100may include a plurality of light-emitting devices120. The disposal (or positioning) of a plurality of pixels is modifiable in various ways. Further, a plurality of signal lines may be further provided on the substrate110. The signal lines may include a plurality of scan lines, a plurality of control lines, a plurality of data lines, and a plurality of driving voltage lines. The signal lines may respectively transmit a scan signal, a control signal, a data signal, and a driving voltage. A plurality of signal lines may be provided to traverse each other in a row direction or a column direction. The respective pixels may include a plurality of transistors and capacitors connected to a plurality of signal lines. The light-emitting device120may include an organic light emitting diode (OLED), and it may be connected to a plurality of signal lines through the transistors and the capacitors. As described, the display panel100may include an organic light emitting panel, but types of the display panel100are not limited thereto. In other words, the display panel100may include various kinds of panels. For example, the display panel100may include a liquid crystal panel, an electrophoretic display panel, an electro-wetting display panel, or the like.

The encapsulation substrate130may be provided to face the substrate110, and may have a similar shape to the substrate110. For example, the encapsulation substrate130and the substrate110may be substantially formed to have a rectangular (or generally rectangular) shape. The encapsulation substrate130may have a similar size to the substrate110, or the encapsulation substrate130may be smaller than the substrate110. The encapsulation substrate130may be made of at least one glass and plastic, and it may be made of a transparent material.

A sealing member150may be further provided between the substrate110and the encapsulation substrate130. The sealing member150may be provided in the peripheral area PA. The sealing member150may be formed to surround the display area DA in a plan view. Therefore, the light-emitting device120provided in the display area DA may be surrounded and sealed by the sealing member150, the substrate110, and the encapsulation substrate130. As such, the substrate110and the encapsulation substrate130may be bonded together by the sealing member150. The sealing member150may be formed by a process of applying a glass material, such as frit, to the peripheral area PA provided between the substrate110and the encapsulation substrate130and irradiating ultraviolet (UV) rays thereto to cure the same.

Most of the region of the substrate110is covered by the encapsulation substrate130. A predetermined region of the substrate110may not be covered by the encapsulation substrate130, but may be exposed to the outside. A driving circuit chip170may be provided on the predetermined region of the substrate110not covered by the encapsulation substrate130. The driving circuit chip170may be provided at (or near) an edge on one side of the substrate110, for example, a bottom edge of the substrate110. This, however, is an example, and the driving circuit chip170may have various modifiable positions. For example, the driving circuit chip170may be provided on a top edge of the substrate110. The driving circuit chip170may be connected to a plurality of pixels provided in the display area DA, and may transmit various signals to a plurality of pixels. For example, the driving circuit chip170may supply a scan signal, a control signal, a data signal, and a driving voltage.

A flexible circuit board may be further provided on an edge of one side of the substrate110. A circuit for controlling driving of the display panel100may be disposed on the flexible circuit board, and it may be attached to an edge on one side of the substrate110.

The touch sensor200may sense a contact of an external object, such as a hand or a pen, generated in the touch sensing region TA. The touch sensor200may also sense the case in which the external object hovers while it is provided near or has already approached the same in addition to the case in which the external object directly contacts the same.

The touch sensor200may be provided on an external side of the display panel100(i.e., an on-cell type) or on an internal side thereof (i.e., an in-cell type). Further, the touch sensor200may be provided on an additional panel and may be attached to the display panel100(i.e., an add-on type). The case in which the touch sensor200is provided on the external side of the display panel100will now be described. However, exemplary embodiments are not limited thereto, and the touch sensor200may have various changeable positions.

The touch sensor200may be provided on the encapsulation substrate130. An anti-reflection layer for reducing reflection of external light may be further provided on the touch sensor200. The anti-reflection layer may include a polarization layer including a linear polarizer and a retarder. A cover window may be further provided on the touch sensor200. The cover window may protect the touch sensor200and the display panel100provided thereunder.

The touch sensor200includes a touch sensing electrode240provided in the touch sensing region TA, a touch extending wire245extended to the touch sensing electrode240, and a touch pad250provided to an end of the touch extending wire245.

The touch sensing electrode240may include a first touch sensing electrode241extending in a first direction X, and a second touch sensing electrode242extending in a second direction Y traversing (or crossing) the first direction X.

The first touch sensing electrode241may include a plurality of first sensing cells241adisposed in the first direction X, and a plurality of first connectors241bextending in the first direction X and connecting the first sensing cells241a. The first touch sensing electrode241may represent a transmitter (Tx) touch electrode for receiving a first touch signal for sensing a coordinate value of the second direction Y. The first sensing cell241amay substantially have a rhombus shape. This, however, is an example, and the first sensing cell241amay have various modifiable shapes. For example, the first sensing cell241amay be formed to be polygonal such as hexagonal, or circular or oval. The first sensing cell241amay be formed to have a mesh shape. For example, the first sensing cell241amay form a mesh shape as a plurality of conductive fine lines that may be disposed to cross each other. Further, the first sensing cell241amay have various shapes, such as protrusions, to improve sensitivity of the touch sensor.

The second touch sensing electrode242may include a plurality of second sensing cells242adisposed in the second direction Y, and a plurality of second connectors242bextending in the second direction Y and connecting a plurality of second sensing cells242ato each other. The second touch sensing electrode242may represent a receiver (Rx) touch electrode for receiving a second touch signal for sensing a coordinate value of the first direction X. The second sensing cell242amay substantially have a rhombus shape. This, however, is an example, and the second sensing cell242amay have various modifiable shapes. For example, the second sensing cell242amay be formed to be polygonal, such as hexagonal, circular, or oval. The second sensing cell242amay be formed to have a mesh shape. For instance, the second sensing cell242amay form a mesh shape as a plurality of conductive fine lines that cross each other. Further, the second sensing cell242amay have various shapes, such as protrusions, to improve sensitivity of the touch sensor.

The first touch sensing electrode241and the second touch sensing electrode242may be provided on different layers. In a plan view, the first sensing cell241aand the second sensing cell242amay neighbor each other, and the first connector241band the second connector242bmay overlap each other and may be insulated from each other by an insulating layer. For instance, an insulating layer may be provided between the first touch sensing electrode241and the second touch sensing electrode242. This, however, is an example, and at least part of the first touch sensing electrode241and the second touch sensing electrode242may be provided on the same layer. For example, the first sensing cell241aand the second sensing cell242amay be provided on the same layer. In this instance, one of the first connector241band the second connector242bmay be provided on the same layer as the first sensing cell241aand the second sensing cell242a, and the other may be provided on a different layer from the first sensing cell241aand the second sensing cell242a. For example, the first connector241bmay be provided on the same layer as the first sensing cell241aand the second sensing cell242a, and the second connector242bmay be provided on a different layer from the first connector241b. An insulating layer may be provided between the second connector242band the second sensing cell242a, and the second connector242bmay be connected to the second sensing cell242athrough a contact hole formed in the insulating layer.

The touch sensing electrode240may include a low resistance metal, such as at least one of silver (Ag), aluminum (Al), copper (Cu), chromium (Cr), and nickel (Ni), and/or it may include a conductive nanomaterial, such as at least one of silver nanowires and carbon nanotubes. Further, the touch sensing electrode240may include a transparent metal oxide, such as at least one of an indium-tin oxide (ITO) and an indium-zinc oxide (IZO). In addition, the touch sensing electrode240may be formed as a multilayer structure, such as formed including a titanium (Ti)/aluminum (Al)/titanium (Ti) structure. The touch sensing electrode240has low resistance to reduce resistance-capacitance (RC) delay, and it has excellent flexibility so that the touch sensing electrode240is not easily cracked by repeated deformation, such as bending.

The first touch sensing electrode241and the second touch sensing electrode242neighboring each other may form a mutual capacitor functioning as a touch sensor. The mutual capacitor may receive a driving signal through one of the first touch sensing electrode241and the second touch sensing electrode242, and may output a change of an amount of charges caused by a touch by an external object as an output signal through the other touch electrode of the first touch electrode241and the second touch electrode242. Differing from this, a plurality of first touch sensing electrodes241may be separated from each other and a plurality of second touch sensing electrodes242may be separated from each other to form independent touch electrodes. In this instance, the respective touch sensing electrodes may form a self-capacitor as a touch sensor. The self-capacitor may receive a driving signal and may be stored with a predetermined amount of charges, and when a touch is generated, the stored amount of charges changes, and the self-capacitor may output an output signal that is different from the input driving signal.

The touch extending wire245is extended to an end of the touch sensing electrode240. The touch sensing electrode240provided near the peripheral area PA may be extended to the touch extending wire245. An end on a first side of the touch extending wire245may be extended to the touch sensing electrode240and may be provided in the touch sensing region TA, but embodiments are not limited thereto. Most of the touch extending wire245may be provided in the peripheral area PA. An end on a second side of the touch extending wire245is extended to the touch pad250.

The touch pad250may be provided on an end of the touch extending wire245. The touch pad250may be provided in the peripheral area PA. The touch pad250may be provided on a right bottom end of the display panel100. However, the position of the touch pad250is an example, and it is modifiable in various ways. For example, the touch pad250may be provided on a bottom center end or a top right end of the display panel100, or may be divided onto various portions of the display panel100. The touch sensor200may include a plurality of touch pads250. The number of touch pads250may be substantially equivalent to the number of touch extending wires245.

The touch sensor200may further include a flexible printed circuit board310provided on the encapsulation substrate130. The flexible printed circuit board310may be provided in the peripheral area PA and may overlap the touch pad250. The flexible printed circuit board310includes a circuit for receiving a touch signal from the touch sensing electrode240through the touch extending wire245and the touch pad250, and may sense whether a touch is generated.

A touch sensor of the display device according to some exemplary embodiments will now be described with reference toFIGS. 3 to 5.

FIG. 3shows an enlarged top plan view of a predetermined region of a display device according to some exemplary embodiments.FIG. 4shows a cross-sectional view with respect to sectional line IV-IV′ ofFIG. 3according to some exemplary embodiments.FIG. 5shows a cross-sectional view with respect to sectional line V-V′ ofFIG. 3according to some exemplary embodiments. As such,FIGS. 3 to 5show a touch pad of a touch sensor of a display device according to some exemplary embodiments and a peripheral side thereof.

As shown inFIGS. 3 to 5, the touch sensor200of a display device according to some exemplary embodiments includes a touch pad250, a flexible printed circuit board310overlapping the touch pad250, and a conductive bonding member (or structure)500provided between the touch pad250and the flexible printed circuit board310.

The touch pad250may include a second touch pad layer270provided on a first touch pad layer260and the first touch pad layer260.

The first touch pad layer260may be provided on an encapsulation substrate130of the display panel100. The first touch pad layer260may be provided on the encapsulation substrate130, and another layer may be further provided between the first touch pad layer260and the encapsulation substrate130. The first touch pad layer260may be made of a transparent metal oxide. For example, the first touch pad layer260may be made of a transparent metal oxide, such as at least one of an indium-tin oxide (ITO) and an indium-zinc oxide (IZO). The first touch pad layer260may be formed to have a rectangular (or generally rectangular) form extending substantially in the second direction Y in a plan view. The first touch pad layer260may be formed to be a rectangle (or a generally rectangular shape) including two short sides in parallel with the first direction X and two long sides in parallel with the second direction Y. This, however, is an example, and the first touch pad layer260may have various planar shapes.

A passivation layer280may be provided on the first touch pad layer260and the encapsulation substrate130. The passivation layer280may be made of an organic insulating material or an inorganic insulating material, and it may be formed to be a single layer or a multilayer structure. A contact hole285overlapping at least part of the first touch pad layer260is formed in the passivation layer280. At least part of an upper side of the first touch pad layer260may be exposed by the contact hole285.

The second touch pad layer270may be provided on the first touch pad layer260and the passivation layer280. The second touch pad layer270may be provided on the first touch pad layer260. Therefore, the second touch pad layer270may contact the first touch pad layer260, and the second touch pad layer270may be electrically connected to the first touch pad layer260. The second touch pad layer270may be made of various metal materials, such as at least one of molybdenum (Mo), silver (Ag), titanium (Ti), copper (Cu), and aluminum (Al), and may include a single layer or multilayer structure, such as a multilayer structure of molybdenum/aluminum/molybdenum (Mo/Al/Mo). The second touch pad layer270may substantially extend in the second direction Y in a plan view. For instance, the second touch pad layer270may extend in parallel to the first touch pad layer260.

The second touch pad layer270includes a first portion271and a second portion272separated from each other in a plan view, and a extender273for extending to the first portion271and the second portion272. The first portion271and the second portion272may be formed to have a quadrangular (or generally quadrangular) shape, and they may have similar planar shapes. This, however, is an example, and the first portion271and the second portion272may have various modifiable shapes. Further, the first portion271and the second portion272may have different shapes. The extender273may be formed to have a bar (or generally bar) shape extending in the second direction Y. The second touch pad layer270may include a plurality of extender273. For example, as shown inFIGS. 3 and 4, the second touch pad layer270may include two extender273. In this instance, the two extender273may extend in parallel to each other. For instance, the two extender273may extend in the second direction Y. The extender273may be narrower (e.g., in the first direction X) than the first portion271and the second portion272. Further, the extender273may be narrower than the first touch pad layer260. The extender273may further include a protrusion275protruding in the first direction X.

As described above, a sealing member150may be provided between the substrate110and the encapsulation substrate130. The sealing member150and the touch pad250are provided in the peripheral area PA. The sealing member150and the touch pad250may overlap each other in the peripheral area PA. In this instance, the sealing member150may be provided below the encapsulation substrate130, and the touch pad250may be provided over the encapsulation substrate130. The sealing member150may be provided between the substrate110and the encapsulation substrate130to seal the light-emitting device120therebetween, and a curing process may be performed by irradiating UV rays. In this instance, when the touch pad250is formed of an opaque metal material, a portion where the sealing member150and the touch pad250overlap each other may be improperly cured. According to some exemplary embodiments, since the second touch pad layer270of the touch pad250is made of a metal material and the first touch pad layer260is made of a transparent metal oxide, the process for curing the sealing member150may be properly performed. In some exemplary embodiments, the extender273of the second touch pad layer270is formed to be narrower than the first portion271and the second portion272, and it may be formed to be narrower than the first touch pad layer260. The sealing member150overlaps the extender273of the second touch pad layer270, and the sealing member150does not overlap the first portion271and the second portion272such that the process for curing the sealing member150may be properly performed.

When the touch pad250is totally formed to be narrow so as to perform the curing process, resistance of the touch pad250may increase. In some exemplary embodiments, the touch pad250includes a first touch pad layer260made of a transparent metal oxide and a second touch pad layer270made of a metal material. To this end, the first touch pad layer260is formed to be relatively wide, and the extender273of the second touch pad layer270is formed to be relatively narrow, thereby preventing resistance of the touch pad250from increasing. In addition, the extender273of the second touch pad layer270is allowed to partly include the protrusion275, thereby preventing the increase of resistance.

The flexible printed circuit board310may overlap the touch pad250. A flexible printed circuit pad320may be provided on the flexible printed circuit board310. The flexible printed circuit pad320may overlap the touch pad250. The flexible printed circuit pad320may overlap the first touch pad layer260of the touch pad250, and may overlap the second touch pad layer270. The flexible printed circuit pad320may be provided to face the touch pad250. The flexible printed circuit pad320may be provided to face the second touch pad layer270of the touch pad250. The flexible printed circuit pad320is connected to a predetermined circuit provided in the flexible printed circuit board310. The flexible printed circuit pad320may be formed of a metal material. The flexible printed circuit pad320may be formed to be a rectangle (or generally a rectangle) substantially extending in the second direction Y in a plan view. The flexible printed circuit pad320may extend parallel to the first touch pad layer260and the extender273of the second touch pad layer270. The flexible printed circuit pad320may be formed to be a rectangle including two short sides parallel to the first direction X and two long sides parallel to the second direction Y. A planar shape of the flexible printed circuit pad320may be similar to a planar shape of the first touch pad layer260. This, however, is an example, and the flexible printed circuit pad320may have various planar shapes.

The conductive bonding member500is provided between the touch pad250and the flexible printed circuit board310. The conductive bonding member500is provided between the second touch pad layer270of the touch pad250and the flexible printed circuit pad320. The conductive bonding member500may overlap the touch pad250and the flexible printed circuit pad320in a plan view. The conductive bonding member500is bonded to the second touch pad layer270of the touch pad250, and the conductive bonding member500may be bonded to the flexible printed circuit pad320. One touch pad250may overlap a plurality of conductive bonding members500. Therefore, the second touch pad layer270and the flexible printed circuit pad320may be electrically connected to each other through a plurality of conductive bonding members500.

The conductive bonding member500may be fusion bonded to the second touch pad layer270and the flexible printed circuit pad320. The fusion bonding method will now be described. A touch pad250including a first touch pad layer260and a second touch pad layer270is formed on the encapsulation substrate130, and a flexible printed circuit pad320is formed on the flexible printed circuit board310. A resin including at least one conductive bonding member500is applied to the touch pad250and the encapsulation substrate130. The flexible printed circuit board310is provided to overlap the conductive bonding member500and the touch pad250. In this instance, the conductive bonding member500may contact the second touch pad layer270, and it may contact the flexible printed circuit pad320. When heat of 150 degrees Celsius to 170 degrees Celsius is applied to the conductive bonding member500and around the same, the conductive bonding member500may melt and may be bonded to the second touch pad layer270provided below the conductive bonding member500. Simultaneously, the conductive bonding member500may be bonded to the flexible printed circuit pad320provided thereon. For instance, the conductive bonding member500may be bonded to the second touch pad layer270and the flexible printed circuit pad320by applying heat and melting the conductive bonding member500.

The fusion bonding method is an example, and the conductive bonding members500may be bonded to the second touch pad layer270and the flexible printed circuit pad320according to another or additional method. For example, the conductive bonding members500may be ultrasonic wave bonded to the second touch pad layer270and the flexible printed circuit pad320. An ultrasonic wave bonding method will now be described. A touch pad250including a first touch pad layer260and a second touch pad layer270is formed on the encapsulation substrate130, and a flexible printed circuit pad320is formed on the flexible printed circuit board310. A resin including at least one conductive bonding member500is applied to the touch pad250and the encapsulation substrate130. A flexible printed circuit board310is provided to overlap the conductive bonding member500and the touch pad250. In this instance, the conductive bonding member500may contact the second touch pad layer270, and may contact the flexible printed circuit pad320. An ultrasonic wave vibration is applied to the conductive bonding member500and the surrounding area thereof to thus cause a molecular movement on a contact side between the conductive bonding member500and the second touch pad layer270and between the conductive bonding member500and the flexible printed circuit pad320. As such, heat is generated on the contact side between the conductive bonding member500and the second touch pad layer270such that the conductive bonding member500may be bonded to the second touch pad layer270. Simultaneously, heat may be generated on the contact side between the conductive bonding member500and the flexible printed circuit pad320so that the conductive bonding member500may be bonded to the flexible printed circuit pad320. In addition, the conductive bonding member500may be bonded to the second touch pad layer270and the flexible printed circuit pad320through various metal bonding methods.

The conductive bonding member500may be circular in a plan view. This, however, is an example, and the conductive bonding member500may have various modifiable planar shapes. The conductive bonding member500may be made of a metal material. For example, it may be formed of various metal materials, such as at least one of tin (SN), tin-bismuth (Sn—Bi), tin-silver (Sn—Ag), tin-indium (Sn—In), and indium-bismuth (In—Bi). The conductive bonding member500may be made of a metal material that melts at a predetermined temperature. When the fusion bonding method is used, heat corresponding to a melting point of the conductive bonding member500is applied such that the conductive bonding member500may be bonded to the second touch pad layer270and the flexible printed circuit pad320. In this instance, the temperature of the heat applied to the conductive bonding member500is variable by the material of the conductive bonding member500.

According to some embodiments, the resin including the conductive bonding member500may be configured to reduce thermal stresses and strains due to differences in coefficients of thermal expansion between surrounding components, such as amongst the conductive bonding member500, the flexible circuit pad320, the flexible printed circuit board310, the extender273, and the first touch pad layer260. The resin may also serve to reduce mechanical, shock, and vibration stresses and strains to further increase the reliability of the electrical connection between flexible printed circuit board310and first touch pad layer260. In addition, the resin may be configured to improve a distribution of a plurality of conductive bonding members500between flexible printed circuit pad320and first touch pad layer260. In some embodiments, an underfill between the conductive bonding members500may be additionally (or alternatively) utilized.

When an anisotropic conductive film (ACF) is used as the conductive bonding member500instead of a metal material, adherence may be low and resistance may also be low. The anisotropic conductive film may be formed of a conductive ball generated by coating a metal film on a surface of a polymer ball. However, as an area of the display area DA increases, the area of the peripheral area PA relatively reduces, and the size of the touch pad250accordingly reduces. When an anisotropic conductive film is provided between the touch pad250and the flexible printed circuit pad320and a compression process is performed, pressure is applied to the conductive ball. When the size of the touch pad250reduces, the pressure applied to the conductive ball may increase and the conductive ball may be broken. When the conductive ball is broken, it loses a restoration force and its reliability is lowered.

According to some exemplary embodiments, reliability is improved by electrically connecting the touch pad250and the flexible printed circuit pad320through the conductive bonding member500made of a metal material. The conductive bonding member500and the touch pad250do not simply contact each other, but they are bonded with each other by a method, such as fusion bonding or ultrasonic wave bonding, so adherence between the conductive bonding member500and the touch pad250may be increased and the resistance may be reduced. For the above-noted bonding, the second touch pad layer270contacting the conductive bonding member500may be made of a metal material from among the first touch pad layer260and the second touch pad layer270configuring the touch pad250. In a like manner, the conductive bonding member500and the flexible printed circuit pad320do not simply contact each other, but they are bonded with each other by a method, such as fusion bonding or ultrasonic wave bonding, so adherence between the conductive bonding member500and the flexible printed circuit pad320may be increased and resistance may be reduced.

According to various exemplary embodiments, the display panel100of a display device may include the substrate110and the encapsulation substrate130facing the substrate110, the sealing member150may be provided between the substrate110and the encapsulation substrate130to seal the light-emitting device120therebetween, and the touch sensor200may be provided on the encapsulation substrate130, but embodiments are not limited thereto. Instead of the encapsulation substrate130and the sealing member150, a thin film encapsulation layer may be provided on the substrate110. In this instance, the light-emitting device120may be provided between the substrate110and the thin film encapsulation layer, and the touch sensor200may be provided on the thin film encapsulation layer. The thin film encapsulation layer may seal the light-emitting device120to prevent external moisture and oxygen from permeating. The thin film encapsulation layer may have a multi-layered structure. For example, the thin film encapsulation layer may have a structure in which at least one inorganic film and at least one organic film are stacked.

A display device according to some exemplary embodiments will now be described with reference toFIG. 6.

The display device according to some exemplary embodiments described in association withFIG. 6mostly corresponds to the display device described in association withFIGS. 1 to 5, so no repeated portions will be described. The touch pad250_1described hereinafter is different from the touch pad250.

FIG. 6shows an enlarged top plan view of a predetermined region of a display device according to some exemplary embodiments.FIG. 6shows a touch pad250_1of a touch sensor of a display device according to an exemplary embodiment, and a peripheral side thereof.

In a like manner of the above-described exemplary embodiments, the display device according to some exemplary embodiments may include a display panel and a touch sensor. As shown inFIG. 6, the touch sensor includes a touch pad250_1, and the touch pad250_1includes a first touch pad layer260and a second touch pad layer270_1. The touch pad250_1overlaps the sealing member150, the conductive bonding member500, and the flexible printed circuit pad320.

In the previous exemplary embodiments, the extender273of the first touch pad layer260and the second touch pad layer270may extend in parallel. Further, the second touch pad layer270may extend in parallel to the flexible printed circuit pad320. As seen inFIG. 6, the extender273_1of the second touch pad layer270_1may extend in an oblique way with respect to a length direction of the first touch pad layer260. Further, the extender273_1of the second touch pad layer270_1may extend in an oblique way with respect to a length direction of the flexible printed circuit pad320. The first touch pad layer260and the flexible printed circuit pad320may each be formed to be a rectangle substantially extending in the second direction Y in a plan view. The extender273_1of the second touch pad layer270_1may be formed to have a bar shape extending in an oblique way with respect to the second direction Y. The second touch pad layer270_1may include a plurality of extenders273_1. In this instance, a plurality of extenders273_1may extend in parallel to each other.

As the extender273_1of the second touch pad layer270_1extends in an oblique way with respect to the first touch pad layer260, the contact area of the first touch pad layer260and the second touch pad layer270_1increases compared to the case in which the same extends in parallel to the first touch pad layer260, thereby reducing resistance. In a like manner, as the extender273_1of the second touch pad layer270_1extends in an oblique way with respect to the flexible printed circuit pad320, the bonding area of the second touch pad layer270_1and the conductive bonding member500may be increased compared to the case in which the same extends in parallel to the flexible printed circuit pad320. Accordingly, resistance between the second touch pad layer270_1and the flexible printed circuit pad320may be reduced.

A display device according to some exemplary embodiments will now be described with reference toFIG. 7.

The display device according to some exemplary embodiments described in association withFIG. 7mostly correspond to the display device described in association withFIGS. 1 to 5, so no repeated portions will be described. The touch pad270_2described hereinafter has a different shape from the touch pad250.

FIG. 7shows an enlarged top plan view of a predetermined region of a display device according to some exemplary embodiments.FIG. 7shows a touch pad270_2of a touch sensor of a display device according to an exemplary embodiment, and a peripheral side thereof.

In a like manner of the previous exemplary embodiments, the display device according to some exemplary embodiments may include a display panel and a touch sensor. As shown inFIG. 7, the touch sensor includes a touch pad250_2, and the touch pad250_2includes a first touch pad layer260and a second touch pad layer270_2. The touch pad250_2overlaps the sealing member150, the conductive bonding member500, and the flexible printed circuit pad320.

In the previous exemplary embodiments, the second touch pad layer270may include a plurality of extenders273, and the plurality of extenders273may extend in parallel to each other. As seen inFIG. 7, the second touch pad layer270_2may include a plurality of extenders273_2, and the plurality of extenders273_2may extend in different directions. The second touch pad layer270_2may include a plurality of extenders273_2. Distances among the plurality of extenders273_2may become greater as the extenders273_2become more distant from the second portion272. This, however, is an example, and the distances among the plurality of extenders273_2may be reduced as the extenders273_2become more distant from the second portion272. In another example, the distances among the plurality of extenders273_2may become greater as the extenders273_2approach a middle region between first portion271and second portion272and may become smaller as the extenders273_2approach the first portion271and the second portion272. A plurality of extenders273_2may extend in an oblique way with respect to the first touch pad layer260. This, however, is an example, and some of a plurality of extenders273_2may extend in parallel to the first touch pad layer260, and others thereof may extend in an oblique way with respect to the first touch pad layer260. Further, a plurality of extenders273_2may extend in an oblique way with respect to the flexible printed circuit pad320. This, however, is an example, and some of a plurality of extenders273_2may extend in parallel to the flexible printed circuit pad320, and the others thereof may extend in an oblique way with respect to the flexible printed circuit pad320.

A display device according to some exemplary embodiments will now be described with reference toFIG. 8.

The display device according to some exemplary embodiments described in association withFIG. 8mostly correspond to the display device described in association withFIGS. 1 to 5, so no repeated portions will be described. The touch pad270_3described hereinafter has a different shape from the touch pad250.

FIG. 8shows an enlarged top plan view of a predetermined region of a display device according to some exemplary embodiments.FIG. 8shows a touch pad270_3of a touch sensor of a display device according to an exemplary embodiment, and a peripheral side thereof.

In a like manner of the previous exemplary embodiments, the display device according to some exemplary embodiments includes a display panel and a touch sensor. As shown inFIG. 8, the touch sensor includes a touch pad250_3, and the touch pad250_3includes a first touch pad layer260and a second touch pad layer270_3. The touch pad250_3overlaps the sealing member150, the conductive bonding member500, and the flexible printed circuit pad320.

In the previous exemplary embodiments, the second touch pad layer270may include two extenders273. As seen inFIG. 8, the second touch pad layer270_3may include three extenders273_3. As the second touch pad layer270_3includes three extenders273_3, resistance may be reduced by increasing the contact area of the first touch pad layer260and the second touch pad layer270_3compared to the case in which the touch pad250includes two extenders273. In a like manner, as the second touch pad layer270_3includes three extenders273_3, the bonding area of the second touch pad layer270_3and the conductive bonding member500may be increased compared to the case in which the second touch pad layer270includes two extenders273. By this, resistance between the second touch pad layer270_3and the flexible printed circuit pad320may be reduced.

In a like manner of the previous exemplary embodiments, a plurality of extenders273_2of the second touch pad layer270_3may extend in parallel to the first touch pad layer260and the flexible printed circuit pad320, and/or the extenders273_3may extend in an oblique direction. Further, some of a plurality of extenders273_3of the second touch pad layer270_3may extend in an oblique way with respect to the first touch pad layer260and the flexible printed circuit pad320. In addition, a extender, such as at least one of extenders273_1,273_2, and273_3, of a second touch pad layer, such as at least one of second touch pad layers270_1,270_2, and270_3, may include protrusions.

Although certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concepts are not limited to such embodiments, but rather to the broader scope of the accompanying claims and various obvious modifications and equivalent arrangements as would be apparent to one of ordinary skill in the art.