Touch panel and manufacturing method thereof

A touch panel includes a substrate, a first signal line, and a second signal line. The first signal line extends on the substrate in a first direction and includes a first height from the substrate. The second signal line extends on the substrate in a second direction crossing the first direction and includes a second height from the substrate. The second signal line is disposed in the same layer as the first signal line. The second height is greater than the first height.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean Patent Application No. 10-2015-0100640, filed on Jul. 15, 2015, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Field

Exemplary embodiments relate to a touch panel and a method for manufacturing the same.

Discussion

Conventional touch panels may recognize a touch by a pen or a user's finger as a means for inputting a signal to a display device. A touch panel may be disposed on the display panel, such as an organic light emitting diode (OLED) display, a liquid crystal display (LCD), and the like. Typical touch panels may include a substrate and a touch sensor unit disposed on the substrate to detect a touch. A capacitive type touch sensor unit may detect a touch by sensing a variation in capacitance generated between a first signal line and a second signal line crossing each other based on the presence of an input object, e.g., a stylus, finger, etc.

SUMMARY

One or more exemplary embodiments provide a touch panel including a touch sensor unit with limited or suppressed visual recognition.

One or more exemplary embodiments provide a method of manufacturing a touch panel including a touch sensor unit limited or suppressed visual recognition.

According to one or more exemplary embodiments, a touch panel includes a substrate, a first signal line, and a second signal line. The first signal line extends on the substrate in a first direction and includes a first height from the substrate. The second signal line extends on the substrate in a second direction crossing the first direction and includes a second height from the substrate. The second signal line is disposed in the same layer as the first signal line. The second height is greater than the first height.

According to one or more exemplary embodiments, a method of manufacturing a touch panel includes: forming a first signal line on a substrate, the first signal line extending in a first direction; forming a first insulating layer on the substrate, the first insulating layer covering the first signal line and comprising an opening extending in a second direction crossing the first direction; and forming a second signal line in the opening, the second signal line extending in the second direction. A first height of the first signal line from the substrate is smaller than a second height of the second signal line from the substrate.

According to one or more exemplary embodiments, the respective heights of the first and second signal lines enables incident light to be reflected from the first and second signal lines, but because the paths of the reflected light off the first and second signal lines are substantially similar, the first and second signal lines are not readily visible to an observer.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1is a plan view of a touch panel, according to one or more exemplary embodiments. Although specific reference will be made to this particular implementation, it is also contemplated that the touch panel may embody many forms and include multiple and/or alternative components.

As shown inFIG. 1, the touch panel is configured to detect a touch (or hovering interaction), and includes a substrate SUB, a wiring part W, and a touch sensor unit TS. The touch panel may include a touch controller (not illustrated), which may be formed as a flexible printed circuit board (FPCB) or a printed circuit board (PCB) connected to the wiring part W. It is contemplated, however, that any other suitable implementation of a touch controller may be utilized in association with exemplary embodiments described herein. The touch controller may calculate (or otherwise determine) information about where a user touches (or otherwise interacts with) the touch panel by digitizing an analog electrical signal transmitted from the touch panel as a digital signal using, for instance, a converter or the like.

The substrate SUB may be flexible, and may include any suitable material, such as, for instance, an organic material, an inorganic material, glass, a metal, such as stainless steel, etc. Although the substrate SUB may be described as flexible, it is not limited thereto, and it may be stretchable, foldable, bendable, or rollable. Given that the substrate SUB is flexible, stretchable, foldable, bendable, or rollable, the entire touch panel may be flexible, stretchable, foldable, bendable, or rollable.

The wiring part W may be disposed in a peripheral region of the substrate SUB, e.g., disposed outside a touch sensing region of the substrate SUB. The wiring part W may be connected to the touch sensor unit TS. The wiring part W may couple the touch sensor unit TS to the touch controller, and may include an opaque conductive material, such as a metal, or the like, or a transparent conductive material. The wiring part W may be formed on the substrate SUB using the same process as (or a different process from) the process utilized to form the touch sensor unit TS.

The touch sensor unit TS is where a touch may be directly detected. The entire touch sensor unit TS may be transparently formed, however, exemplary embodiments are not so limited. The touch sensor unit TS is disposed on the substrate SUB, and may be formed as a capacitive type touch sensor unit. The touch sensor unit TS includes, on the substrate SUB, a first signal line SL1extending in a first direction (e.g., an x-axis direction) to be connected to the wiring part W, and a second signal line SL2extending in a second direction (e.g., a y-axis direction) crossing the first direction to be connected to the wiring part W.

As seen inFIG. 1, a plurality of first signal lines SL1are present, and the plurality of first signal lines SL1may be respectively and sequentially arranged in the second direction, e.g., spaced apart from one another in the second direction. The first signal lines SL1may extend straight in the first direction, but they are not limited thereto, and may be bent at least once to extend in the first direction. A plurality of second signal lines SL2are also present, and the plurality of second signal lines SL2may be respectively and sequentially arranged in the first direction, e.g., spaced apart from one another in the first direction. The second signal lines SL2extend straight in the second direction, but they are not limited thereto, and may be bent at least once to extend in the second direction. In this manner, the first and second signal lines SL1and SL2cross each other, but are insulated from each other. The first and second signal lines SL1and SL2are disposed on the same layer that is disposed on the substrate SUB.

According to one or more exemplary embodiments, when voltages are applied to the plurality of first signal lines SL1and the plurality of second signal lines SL2, capacitance is generated between each of the first signal lines SL1and each of the second signal lines SL2. In this manner, when the touch sensor unit TS detects a touch, capacitance changes at a position where the touch is detected to cause the voltage applied to the first signal line SL1or second signal line SL2to vary. To this end, the touch sensor unit TS of the touch panel may detect where on the touch panel the touch has occurred based on the variance of the capacitance.

FIG. 2is a plan view of portion “A” of the touch panel ofFIG. 1, according to one or more exemplary embodiments.FIG. 3is a cross-sectional view of the touch panel ofFIG. 2taken along sectional line III-III, according to one or more exemplary embodiments.

As shown inFIGS. 2 and 3, the touch sensor unit TS of the touch panel includes the first signal line SL1, a first insulating layer IL1the second signal line SL2, and a second insulating layer IL2.

The first signal line SL1includes a first sensing electrode TP1and a first connecting portion CP1. A plurality of first sensing electrodes TP1are present, and the plurality of first sensing electrodes TP1are respectively spaced apart from one another in the first direction. The plurality of first sensing electrodes TP1respectively includes metal mesh patterns of electrodes. Since the first sensing electrode TP1includes a metal mesh formed from a metal, a signal transmitted via the first sensing electrode TP1is suppressed from being delayed. It is contemplated, however, that although the first sensing electrode TP1is shown as including a metal mesh pattern, exemplary embodiments are not limited thereto. Further, the first sensing electrode TP1may be formed from a transparent conductive material, such as a silver nanowire (AgNW), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), indium tin oxide (ITO), indium zinc oxide (IZO), etc. It is also contemplated that one or more conductive polymers (ICP) may be utilized, such as, for example, polyaniline (PANI), poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), etc.

The first sensing electrode TP1has a first height H1from the substrate SUB, e.g., a thickness dimension measured in a third direction (e.g., a z-axis direction), which may be orthogonal to the first and second directions. In this manner, the first height H1may be a distance from a surface (e.g., upper surface) of the substrate SUB to a surface (e.g., upper surface) of the first sensing electrode TP1.

The first connecting portion CP1interconnects each of the plurality of first sensing electrodes TP1, e.g., neighboring (or adjacent) first sensing electrodes TP1. The first sensing electrode TP1and the first connecting portion CP1are integrally formed, but exemplary embodiments are not limited thereto. To this end, the first sensing electrode TP1and the first connecting portion CP1may be formed of the same or different materials from one another. The first connecting portion CP1crosses a second connecting portion CP2while being insulated from the first connecting portion CP1.

The first connecting portion CP1may have the same first height H1from the substrate SUB as the first sensing electrode TP1. In this manner, the first height H1may be a distance from the surface of the substrate SUB to a surface (e.g., upper surface) of the first connecting portion CP1. When the first sensing electrode TP1and the first connecting portion CP1respectively have the first height H1from the substrate SUB, the first signal line SL1has the first height H1from the substrate SUB. As such, the first height H1may be a distance from the surface of the substrate SUB to a surface (e.g., upper surface) of the first signal line SL1.

The first insulating layer IL1covers the first signal line SL1. That is, the first insulating layer IL1is disposed on the substrate SUB and covers the first sensing electrode TP1and the first connecting portion CP1. The first insulating layer IL1includes an opening OP in which the second signal line SL2is disposed. The first insulating layer IL1may include at least one of inorganic and organic materials, including at least one of a silicon nitride, a silicon oxide, and the like. The opening OP in the first insulating layer IL1may have the same planar shape as the second signal line SL2. Further, the opening OP may include a first sub-opening SOP1and a second sub-opening SOP2.

The second sensing electrode TP2of the second signal line SL2is disposed inside the first sub-opening SOP1. A plurality of first sub-openings SOP1are present, and the plurality of first sub-openings SOP1are respectively dispose about the second sub-openings SOP2. That is, the second sub-openings SOP2are disposed between first sub-openings SOP1. In this manner, the first sub-openings SOP1and the second sub-openings SOP2are spaced apart from each other. The first sub-opening SOP1may be formed deeper in a surface (e.g., upper surface) of the first insulating layer IL1than the second sub-opening SOP1.

The second connecting portion CP2of the second signal line SL2is disposed inside the second sub-opening SOP2. In this manner, the second sub-opening SOP2interconnects neighboring (e.g., adjacent) first sub-openings SOP1. That is, the second sub-opening SOP2communicates with the first sub-opening SOP1, such that the second connecting portion CP2may interconnect adjacent second sensing electrodes TP2. The second sub-opening SOP2at least partially crosses the first connecting portion CP1, but is insulated from the first connecting portion CP1. The first insulating layer IL1is disposed between the second sub-opening SOP2and the first connecting portion CP1. The first connecting portion CP1crossing the second sub-opening SOP2, and being insulated therefrom, may be at least partially formed shallower from the surface (e.g., upper surface) of the first insulating layer IL1than the first sub-opening SOP1. It is also noted that the depth of the second sub-opening SOP2may be smaller than the depth of the first sub-opening SOP1.

As seen inFIG. 3, the second signal line SL2is disposed on the same layer over the substrate SUB as the first signal line SL1. To this end, the second signal line SL2includes the second sensing electrode TP2and the second connecting portion CP2. A plurality of second sensing electrodes TP2are present, and the plurality of second sensing electrodes TP2is respectively spaced apart from one another in the second direction. The plurality of second sensing electrodes TP2respectively includes metal mesh patterns of electrodes. Since the second sensing electrode TP2includes the metal mesh formed from a metal, a signal transmitted via the second sensing electrode TP2is suppressed from being delayed. It is noted, however, that although the second sensing electrode TP2is shown as including a metal mesh pattern, exemplary embodiments are not limited thereto. Further, the second sensing electrode TP2may be formed from a transparent conductive material, such as a silver nanowire (AgNW), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), indium tin oxide (ITO), indium zinc oxide (IZO), etc. It is also contemplated that one or more conductive polymers (ICP) may be utilized, such as, for example, polyaniline (PAM), poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), etc.

The second sensing electrode TP2is disposed inside the first sub-opening SOP1of the first insulating layerIL1and, as a result, the second sensing electrode TP2has a second height H2from the substrate SUB (e.g., a thickness dimension measured in the third direction), which is greater than the first height H1. In this manner, the second height H2may be a distance from the surface (e.g., upper surface) of the substrate SUB to a surface (e.g., upper surface) of the second sensing electrode TP2.

The second connecting portion CP2interconnects the plurality of second sensing electrodes TP2, e.g., neighboring (or adjacent) second sensing electrodes TP2. The second sensing electrode TP2and the second connecting portion CP2are integrally formed, but exemplary embodiments are not limited thereto. To this end, the second sensing electrode TP2and the second connecting portion CP2may be formed of the same or different materials from one another. As previously mentioned, the second connecting portion CP2is disposed inside the second sub-opening SOP2of the first insulating layerIL1and, as a result, an upper surface of the second connecting portion CP2is the same distance (e.g., the second height H2) from the substrate SUB as the second sensing electrode TP2. In this manner, the second height H2may be a distance from the surface (e.g., upper surface) of the substrate SUB to a surface (e.g., upper surface) of the second connecting portion CP2.

The second connecting portion CP2crosses the first connecting portion CP1, but is insulated from the first connecting portion CP1because it is at least partially disposed inside the second sub-opening SOP2overlaying the first connecting portion CP1with the first insulating layer disposed therebetween. The second connecting portion CP2crossing the first connecting portion CP1while being separated therefrom may at least partially have a smaller thickness than the second sensing electrode TP2. As described above, since the upper surfaces of the second sensing electrode TP2and the second connecting portion CP2respectively have the second height H2from the substrate SUB, the second signal line SL2has the second height H2from the substrate SUB. In this manner, the second height H2may be a distance from the surface of the substrate SUB to a surface of the second signal line SL2.

According to one or more exemplary embodiments, since the second signal line SL2is disposed inside the opening OP of the first insulating layer IL1, the surface of the second signal line SL2may be disposed on the same plane as the surface of the first insulating layer IL1. That is, the upper surfaces of the second signal line SL2and the first insulating layer IL1may be respectively disposed on the same imaginary line VL, and, thereby, coplanar. In order for the surfaces of the second signal line SL2and the first insulating layer IL1to be disposed on the same line, the surfaces of the second signal line SL2and the first insulating layer IL1may be polished, e.g., pre-polished.

As seen inFIG. 3, the second insulating layer IL2covers the first insulating layer IL1. That is, the second insulating layer IL2is disposed on the substrate SUB and covers the first insulating layer IL1and the second signal line SL2. The second insulating layer IL2may include at least one of inorganic and organic materials, including at least one of a silicon nitride, a silicon oxide, and the like. The second insulating layer IL2may include the same material as the first insulating layer IL1.

According to one or more exemplary embodiments, since the first and second signal lines SL1and SL2respectively have the first and second heights H1and H2from the substrate SUB and are disposed on the same layer over the substrate SUB, when external light is radiated to and reflected from each of the first and second signal lines SL1and SL2, the visibility of the first and second signal lines SL1and SL2are suppressed from being recognized from the outside since paths taken by the reflected light are not significantly different from each other. In addition, when the first signal line SL1is covered by the first insulating layer IL1and the second signal line SL2is disposed inside the opening OP of the first insulating layer IL1to minimize a thickness of the first insulating layerIL1differences in the paths taken by the external light radiated to and reflected from each of the first and second signal lines SL1and SL2may be minimized because the first and second signal lines SL1and SL2respectively have a substantially similar thicknesses. As such, the first and second signal lines SL1and SL2are respectively suppressed from being recognized from the outside. That is, the touch panel in which the first and second signal lines SL1and SL2are suppressed from being recognized from the outside is provided.

Furthermore, according to one or more exemplary embodiments, since the first sensing electrode TP1and the first connecting portion CP1included as part of the first signal line SL1are integrally formed, and the second sensing electrode TP2and the second connecting portion CP2included as part of the second signal line SL2are integrally formed, contact resistance between the first sensing electrode TP1and the first connecting portion CP1and contact resistance between the second sensing electrode TP2and the second connecting portion CP2are minimized. In this manner, signals respectively transmitted via the first and second signal lines SL1and SL2are suppressed from being delayed. That is, since the signals are suppressed from being delayed, the touch panel including the touch sensor unit TS may be provided with improved touch sensitivity.

Additionally, according to one or more exemplary embodiments, since both the first sensing electrode TP1and the second sensing electrode TP2of the touch sensor unit TS may include metal mesh patterns, the signals respectively transmitted via the first and second signal lines SL1and SL2may be suppressed from being delayed because both the first sensing electrode TP1and the second sensing electrode TP2have lower electrical resistance than a non-mesh transparent conductive oxide, such as indium tin oxide (ITO). That is, since the signals respectively transmitted via the first and second signal lines SL1and SL2are suppressed from being delayed, the touch panel including the touch sensor unit TS may be provided with improved touch sensitivity. It is also noted that the mesh patterns enable the substrate SUB to be flexibly formed, and, overall flexibility is improved. That is, the flexible touch panel may be optimized for a flexible display panel.

According to one or more exemplary embodiments, the first sensing electrode TP1and the second sensing electrode TP2respectively include metal mesh patterns, and, as such, even if stress is generated in the touch panel as the touch panel is bent, the first and second sensing electrodes TP1and TP2including the metal mesh patterns may be respectively and easily bent by the stress because the stress may be distributed across each of the first and second sensing electrodes TP1and TP2. In this manner, the first and second sensing electrodes TP1and TP2may be respectively prevented from being broken by the bending stress. That is, a touch panel may be provided that is prevented from being broken by bending stresses.

A method of manufacturing a touch panel according to one or more exemplary embodiments will now be described with reference toFIGS. 4 to 9. It is noted that the touch panel ofFIGS. 1-3may be manufactured using the method ofFIGS. 4 to 9.

FIG. 4is a flowchart of a process for manufacturing a touch panel, according to one or more exemplary embodiments.FIGS. 5 to 9are respective cross-sectional views of a touch panel at various stages of manufacture, according to one or more exemplary embodiments.

As shown inFIGS. 4 and 5, a first signal line SL1is formed on a substrate SUB (S100). That is, after a buffer layer is formed on the substrate SUB and a metal layer is formed on the buffer layer, the metal layer is patterned using microelectromechanical systems (MEMS) technology, such as a photolithography process using a mask, to form a first signal line SL1including a first sensing electrode TP1and a first connecting portion CP1. The first sensing electrode TP1and the first connecting portion CP1extend in a first direction, are spaced apart from one another in a second direction, and have a first height H1from an upper surface of the substrate SUB in a third direction orthogonal to the first and second directions.

As shown inFIGS. 4 and 6, a first insulating layer IL1covering the first signal line SL1and including an opening OP is formed (S200). That is, after the first insulating layer IL1covering the first signal line SL1is formed and a photoresist layer is formed on the first insulating layerIL1the photoresist layer is exposed to light and developed, thereby forming a photoresist pattern PR. Next, an opening OP including a first sub-opening SOP1and a second sub-opening SOP2is formed in the first insulating layer IL1by selectively etching the first insulating layer IL1using the photoresist pattern PR as a mask. In this manner, the first insulating layer IL1covering the first signal line SL1and including the opening OP that extends in a second direction crossing a first direction is formed.

According toFIGS. 4 and 7, a second signal line SL2is formed inside the opening OP (S300). That is, a metal layer ML is formed on the photoresist pattern PR. Since the metal layer ML is filled in each of the first and second sub-openings SOP1and SOP2of the opening OP, a second sensing electrode TP2and a second connecting portion CP2are respectively formed inside each of the first and second sub-openings SOP1and SOP2of the opening OP. In this manner, the second signal line SL2is formed. Subsequently, by removing the metal layer ML disposed on the photoresist pattern and then ashing or lifting off the photoresist pattern PR from the first insulating layer IL1, a metal material disposed on the second signal line SL2may be removed.

As shown inFIGS. 4 and 8, a surface of the second signal line SL2and a surface of the first insulating layer IL1are polished (S400). For instance, a chemical polishing method using an etchant or a physical polishing method using an abrasive is used to polish the surface of the second signal line SL2and the surface of the first insulating layer IL1. Since the surfaces of the second signal line SL2and the first insulating layer IL1are polished, the surfaces of the second signal line SL2and the first insulating layer IL1are formed on the same imaginary line VL, e.g., are coplanar with one another. Accordingly, the second signal line SL2, which extends on the substrate SUB in the second direction may have a second height H2greater than the first height H1from the substrate SUB is formed inside the opening OP.

According toFIGS. 4 and 9, a second insulating layer IL2covering the first insulating layer IL1is formed (S500). That is, a second insulating layer IL2including the same or similar material as the first insulating layer IL1is formed on the first insulating layer IL1, such that the second insulating layer IL2covering the first insulating layer IL1is formed. It is noted that the first and second insulating layers IL1and IL2positioned at a periphery of the substrate SUB may be respectively etched to form a peripheral opening. As such, a wiring part W connected to a touch controller formed as, for instance, a flexible printed circuit board (FPCB) or a printed circuit board (PCB), may be connected to each of the first and second signal lines SL1and SL2via the peripheral opening.

According to one or more exemplary embodiments, the first and second signal lines SL1and SL2are formed such that they respectively have the first height H1and the second height H2from the substrate SUB and are disposed on the same layer over the substrate SUB. In this manner, when external light is radiated to each of the first and second signal lines SL1and SL2and is then reflected by each of the first and second signal lines SL1and SL2, paths taken by the reflected light are not much different from each other. As such, the method enables a touch panel to be formed in which the first and second signal lines SL1and SL2are suppressed from being recognized from the outside.