Patent Publication Number: US-2023152930-A1

Title: Flexible touch panel and method of manufacturing thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. non-provisional patent application claims priority under 35 U.S.C. § 119 of Korean Patent Application Nos. 10-2021-0157980, filed on Nov. 16, 2021, and 10-2022-0042819, filed on Apr. 6, 2022, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The present disclosure relates to a flexible touch panel and a manufacturing method thereof, and more particularly, to a mutual capacitance type flexible touch panel and a manufacturing method thereof. 
     Flexible circuits and sensors that may maintain functions even when folded or stretched in any direction by external force may be used in various fields such as displays, robots, wearable devices, and bio devices. In particular, a flexible display that may stretch the panel in any direction and may adhere to a curved surface beyond the stage of rollable or folding is in the spotlight as a next-generation technology. A flexible display requires not only an image output function, but also a user interface (UI) that receives an input signal from the user and reflects the intention. Touch recognition is the most representative UI among them. When flexibility is implemented with improved touch panel technology, a touch recognition function may be mounted on various types of electronic devices. However, the touch panel uses a transparent conductive oxide as an electrode material, but since the material itself has a hard property, it is difficult to apply it to a flexible display. 
     SUMMARY 
     The present disclosure provides a flexible touch panel with improved flexibility and touch recognition capability. 
     The present disclosure also provides a method of manufacturing a flexible touch panel that may implement fine patterns. 
     An embodiment of the inventive concept provides a flexible touch panel including a first sensor part extending in a first direction on a substrate, a second sensor part extending in a second direction crossing the first direction on the substrate, and a protective layer surrounding the first and second sensor parts, wherein the first sensor part includes first sensor patterns spaced apart from each other in the first direction, a first connection electrode disposed between the first sensor patterns adjacent to each other, and first connection patterns connecting the first connection electrode and the first sensor patterns to each other, wherein each of the first sensor patterns includes first electrode patterns spaced apart from each other in a form of a mesh and first wiring patterns connecting the adjacent first electrode patterns to each other, wherein each of the first wiring patterns and the first connection patterns has a serpentine structure, wherein the first electrode patterns and the first wiring patterns include the same material as each other. 
     In an embodiment of the inventive concept, a method for manufacturing a flexible touch panel includes: forming a first preliminary protective layer on a carrier substrate; forming a first connection electrode on the first preliminary protective layer; forming an insulating layer covering a portion of the first connection electrode; forming a preliminary electrode film on an entire surface of the first preliminary protective layer; etching the preliminary electrode film to form a first sensor part extending in a first direction and a second sensor part extending in a second direction crossing the first direction; forming a second preliminary protective layer covering the first and second sensor parts; forming a protective layer by etching the first preliminary protective layer and the second preliminary protective layer in shapes corresponding to the first sensor part and the second sensor part; and transferring the first sensor part and the second sensor part to a substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings are included to provide a further understanding of the inventive concept, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the inventive concept and, together with the description, serve to explain principles of the inventive concept. In the drawings: 
         FIG.  1    is a plan view of a flexible touch panel according to embodiments of the inventive concept; 
         FIG.  2    is a plan view illustrating an enlarged area M of  FIG.  1   ; 
         FIG.  3    is a plan view illustrating an enlarged area N of  FIG.  2   ; 
         FIGS.  4 A and  4 B  are cross-sectional views taken along lines A-A′ and B-B′ of  FIG.  3   , respectively; 
         FIG.  5    is a plan view illustrating an enlarged area O of  FIG.  2   ; 
         FIG.  6    is a cross-sectional view taken along line C-C′ of  FIG.  5   ; 
         FIGS.  7 ,  9 ,  11  and  13    are for explaining a method of manufacturing a flexible touch panel according to embodiments of the inventive concept, and are respectively enlarged plan views of area N of  FIG.  2   ; 
         FIGS.  8 ,  10 ,  12 A, and  14 A  are cross-sectional views taken along line A-A′ of  FIGS.  7 ,  9 ,  11 , and  13   , respectively; 
         FIGS.  12 B and  14 B  are cross-sectional views taken along line B-B′ of  FIGS.  11  and  13   , respectively; and 
         FIGS.  15  and  16    are cross-sectional views for explaining a method of manufacturing a flexible touch panel according to embodiments of the inventive concept. 
     
    
    
     DETAILED DESCRIPTION 
     Advantages and features of the inventive concept, and a method of achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the inventive concept is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments are provided so that the disclosure of the inventive concept is complete, and to fully inform those of ordinary skill in the scope of the invention in the technical field to which the inventive concept belongs, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification. 
     The terms used in this specification are for describing embodiments and are not intended to limit the inventive concept. In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used in the specification, in relation to ‘comprises’ and/or ‘comprising’, the mentioned elements, steps, operations and/or elements do not exclude the presence or addition of one or more other elements, steps, operations and/or elements. 
     Further, the embodiments described herein will be described with reference to cross-sectional and/or plan views, which are ideal illustrative views of the inventive concept. In the drawings, thicknesses of films and regions are exaggerated for effective description of technical content. Accordingly, the shape of the illustrative drawing may be modified due to manufacturing technology and/or tolerance. Accordingly, the embodiments of the inventive concept are not limited to the specific form shown, but also include changes in the form generated according to the manufacturing process. Accordingly, the regions illustrated in the drawings have schematic properties, and the shapes of the regions illustrated in the drawings are intended to illustrate a specific shape of the device region and are not intended to limit the scope of the invention. 
     In addition, terms used in the present specification may be interpreted as meanings commonly known to those of ordinary skill in the art, unless otherwise defined. 
       FIG.  1    is a plan view of a flexible touch panel according to embodiments of the inventive concept. 
     Referring to  FIG.  1   , the flexible touch panel  10  may include first sensor parts SP 1  and second sensor parts SP 2  disposed on a substrate SUB. The substrate SUB may include a flexible material. For example, the substrate SUB may include an elastomer such as rubber. The substrate SUB may surround side surfaces of the first sensor parts SP 1  and side surfaces of the second sensor parts SP 2 . As another example, the substrate SUB may further surround the upper and lower surfaces of the first and second sensor parts SP 1  and SP 2 , respectively. 
     Each of the first sensor parts SP 1  may extend in the first direction D 1 . The first sensor parts SP 1  may be arranged parallel to each other in the second direction D 2 . The second direction D 2  may intersect the first direction D 1 . For example, the second direction D 2  may be perpendicular to the first direction D 1 . Each of the second sensor parts SP 2  may extend in the second direction D 2 . The second sensor parts SP 2  may be arranged parallel to each other in the first direction D 1 . 
     Each of the first sensor parts SP 1  may constitute a transmission electrode (e.g., Tx electrode) of the flexible touch panel  10 . Each of the second sensor parts SP 2  may constitute a reception electrode (e.g., Rx electrode) of the flexible touch panel  10 . An electric field may be formed between the first sensor part SP 1  and the second sensor part SP 2 . That is, the first sensor part SP 1  and the second sensor part SP 2  may be charge-coupled. When a touch is applied to the flexible touch panel  10  according to the inventive concept, the electric field generated by the transmission electrode may be absorbed by the touched object, thereby reducing the capacitance between the transmission electrode and the reception electrode. Accordingly, a signal sensed by the reception electrode is changed, and a touch may be sensed using this. That is, the flexible touch panel  10  according to embodiments of the inventive concept may use a mutual capacitance method. The mutual capacitance method is superior to the self capacitance method in terms of accuracy in catching the touch location, and has the advantage of being able to supplement the multi-touch function caused by the ghost touch. 
     Each of the first sensor parts SP 1  and the second sensor parts SP 2  may include the same transparent conductive oxide. For example, each of the first sensor parts SP 1  and the second sensor parts SP 2  may include indium tin oxide (ITO). As another example, each of the first sensor parts SP 1  and the second sensor parts SP 2  may include an opaque metal material such as molybdenum. 
     The first sensor parts SP 1  and the second sensor parts SP 2  may cross each other. In a plan view, the first sensor parts SP 1  and the second sensor parts SP 2  may form a mesh shape. 
     The first sensor parts SP 1  and the second sensor parts SP 2  may be connected to the external connection electrode CNP. A sensing signal measured by the first sensor part SP 1  and the second sensor part SP 2  may be transmitted to an external electronic device through the external connection electrode CNP. The external connection electrode CNP may include the same material as that of the first sensor part SP 1  and the second sensor part SP 2 . As an example, the external connection electrode CNP may include ITO. 
     The frame FR may surround the substrate SUB. As an example, the frame FR may include a printed circuit board (PCB). The frame FR may serve to support the substrate SUB. The frame FR may surround at least one side surface of the substrate SUB. As will be described later, the frame FR may be used as a casting mold for forming the substrate SUB when the flexible touch panel  10  is manufactured. 
       FIG.  2    is a plan view illustrating an enlarged area M of  FIG.  1   . 
     Referring to  FIG.  2   , the first sensor part SP 1  may include first sensor patterns SR 1  spaced apart from each other in the first direction D 1 . For example, the first sensor pattern SR 1  may have a rhombus shape in a plan view. The first sensor part SP 1  may include a first connection electrode CEP 1  between the first sensor patterns SR 1  adjacent to each other in the first direction D 1 . The first connection electrode CEP 1  may be connected to the first sensor patterns SR 1  adjacent thereto in the first direction D 1 . 
     Each of the first sensor patterns SR 1  may include first electrode patterns EP 1  spaced apart from each other in a mesh shape. In a plan view, the first electrode patterns EP 1  may have a rhombus shape. 
     The second sensor part SP 2  may include second sensor patterns SR 2  spaced apart from each other in the second direction D 2 . For example, the second sensor pattern SR 2  may have a rhombus shape in a plan view. The second sensor part SP 2  may include a second connection electrode CEP 2  between the second sensor patterns SR 2  adjacent to each other in the second direction D 2 . The second connection electrode CEP 2  may be connected to the second sensor patterns SR 2  adjacent thereto in the second direction D 2 . The first connection electrode CEP 1  and the second connection electrode CEP 2  may be provided at a point where the first sensor part SP 1  and the second sensor part SP 2  cross each other. The second connection electrode CEP 2  may be provided on the first connection electrode CEP 1 . A portion of the second connection electrode CEP 2  may vertically overlap the first connection electrode CEP 1 . 
     Each of the second sensor patterns SR 2  may include second electrode patterns EP 2  spaced apart from each other in a mesh shape. In a plan view, the second electrode patterns EP 2  may have a rhombus shape. The first sensor pattern SR 1  and the second sensor pattern SR 2  may have substantially the same shape and structure. 
       FIG.  3    is a plan view illustrating an enlarged area N of  FIG.  2   .  FIGS.  4 A and  4 B  are cross-sectional views taken along lines A-A′ and B-B′ of  FIG.  3   , respectively.  FIG.  5    is a plan view illustrating an enlarged area O of  FIG.  2   .  FIG.  6    is a cross-sectional view taken along line C-C′ of  FIG.  5   . Referring to  FIGS.  3  to  6   , the first sensor part SP 1  and the second sensor part SP 2  will be described in more detail. 
     Referring to  FIGS.  3  to  6   , the first electrode patterns EP 1  of the first sensor pattern SR 1  may be connected to each other through the first wiring patterns IP 1 . The first wiring patterns IP 1  may connect the first electrode patterns EP 1  adjacent to each other. The first wiring patterns IP 1  may have a serpentine structure. The first connection electrode CEP 1  and the first sensor pattern SR 1  may be connected to each other through the first connection pattern CIP 1 . The first connection pattern CIP 1  has a serpentine structure and may include first portions CIP 1   a  extending in the first direction D 1  and a second portion CIP 1   b  contacting the first connection electrode CEP 1 . The first portions CIP 1   a  and the second portion CIP 1   b  may be integrally connected to each other. The first connection pattern CIP 1  may connect the first connection electrode CEP 1  and the first electrode pattern EP 1  of the first sensor pattern SR 1  adjacent thereto to each other. The first electrode pattern EP 1  adjacent to the first connection electrode CEP 1  may not have a rhombus shape. 
     The second electrode patterns EP 2  of the second sensor pattern SR 2  may be connected to each other through the second wiring patterns IP 2 . The second wiring patterns IP 2  may connect the second electrode patterns EP 2  adjacent to each other. The second wiring patterns IP 2  may have a serpentine structure. The second wiring patterns IP 2  may have substantially the same shape and structure as the first wiring patterns IP 1 . The second connection electrode CEP 2  and the second sensor pattern SR 2  may be connected to each other through the second connection patterns CIP 2 . The second connection patterns CIP 2  have a serpentine structure and may extend in the second direction D 2 . The second connection patterns CIP 2  may connect the second connection electrode CEP 2  and the second electrode pattern EP 2  of the second sensor pattern SR 2  adjacent thereto to each other. The second electrode pattern EP 2  adjacent to the second connection electrode CEP 2  may not have a rhombus shape. 
     The first wiring patterns IP 1  and the second wiring patterns IP 2  may have substantially the same or similar shapes to each other. The first portions CIP 1   a  of the first connection pattern CIP 1  and the second connection patterns CIP 2  may have substantially the same or similar shapes to each other. 
     Each of the first connection electrode CEP 1 , the second connection electrode CEP 2 , the first connection pattern CIP 1 , the second connection pattern CIP 2 , the first electrode pattern EP 1 , the first wiring pattern IP 1 , the second electrode pattern EP 2 , and the second wiring pattern IP 2  may include the same transparent conductive oxide. For example, each of the first connection electrode CEP 1 , the second connection electrode CEP 2 , the first connection pattern CIP 1 , the second connection pattern CIP 2 , the first electrode pattern EP 1 , the first wiring pattern IP 1 , the second electrode pattern EP 2 , and the second wiring pattern IP 2  may include ITO. As another example, each of the first connection electrode CEP 1 , the second connection electrode CEP 2 , the first connection pattern CIP 1 , the second connection pattern CIP 2 , the first electrode pattern EP 1 , the first wiring pattern IP 1 , the second electrode pattern EP 2 , and the second wiring pattern IP 2  may include the same opaque metallic material (e.g., molybdenum). 
     The first connection patterns CIP 1 , the first electrode patterns EP 1 , and the first wiring patterns IP 1  may be integrally connected to each other. In other words, an interface may not be visible between the first connection patterns CIP 1 , the first electrode patterns EP 1 , and the first wiring patterns IP 1 . As will be described later, by etching the preliminary electrode layer, the first connection patterns CIP 1 , the first electrode patterns EP 1 , and the first wiring patterns IP 1  may be simultaneously formed. 
     The first connection electrode CEP 1  and the first connection patterns CIP 1  may not be integrally formed with each other. In other words, an interface may be visible between the first connection electrode CEP 1  and the first connection patterns CIP 1 . As will be described later, this is because the first connection electrode CEP 1  and the first connection patterns CIP 1  are formed through different processes. 
     For example, a width of each of the first wiring patterns IP 1  may be smaller than a width of each of the first portions CIP 1   a  of the first connection pattern CIP 1 . As another example, a width of each of the first wiring patterns IP 1  may be equal to or greater than a width of each of the first portions CIP 1   a  of the first connection patterns CIP 1 . 
     The second connection electrode CEP 2 , the second connection patterns CIP 2 , the second electrode patterns EP 2 , and the second wiring patterns IP 2  may be integrally connected to each other. In other words, an interface may not be visible between the second connection electrode CEP 2 , the second connection patterns CIP 2 , the second electrode patterns EP 2 , and the second wiring patterns IP 2 . As will be described later, by etching the preliminary electrode layer, the second connection electrode CEP 2 , the second connection patterns CIP 2 , the second electrode patterns EP 2 , and the second wiring patterns IP 2  may be simultaneously formed. 
     For example, a width of each of the second wiring patterns IP 2  may be smaller than a width of each of the second connection patterns CIP 2 . As another example, a width of each of the second wiring patterns IP 2  may be equal to or greater than a width of each of the second connection patterns CIP 2 . 
     An insulating layer ISL may be provided between the first connection electrode CEP 1  and the second connection electrode CEP 2 . The insulating layer ISL may include, for example, at least one of silicon oxide and silicon nitride. The insulating layer ISL may electrically separate the first sensor part SP 1  and the second sensor part SP 2  that cross each other. The insulating layer ISL may cover a portion of the first connection electrode CEP 1 . Specifically, the insulating layer ISL may cover a portion of each of the sidewall and the upper surface of the first connection electrode CEP 1 . A portion of the first connection electrode CEP 1  may be exposed by the insulating layer ISL. The first connection pattern CIP 1  may be connected to a portion of the exposed first connection electrode CEP 1 . Specifically, the second portion CIP 1   b  of the first connection pattern CIP 1  may contact the first connection electrode CEP 1  exposed by the insulating layer ISL. The second portion CIP 1   b  of the first connection pattern CIP 1  may cover the exposed upper surface and sidewalls of the first connection electrode CEP 1 . The second portion CIP 1   b  of the first connection pattern CIP 1  may extend onto the upper surface of the insulating layer ISL. The second portion CIP 1   b  of the first connection pattern CIP 1  may cover a portion of each of the upper surface and the sidewall of the insulating layer ISL. 
     A second connection electrode CEP 2  may be provided on the insulating layer ISL. The second connection electrode CEP 2  may cover a portion of the insulating layer ISL. Specifically, the second connection electrode CEP 2  may cover a portion of each of the sidewall and the top surface of the insulating layer ISL. A portion of the insulating layer ISL may be exposed by the second connection electrode CEP 2 . The second connection electrode CEP 2  may be spaced apart from the second portion CIP 1   b  of the first connection pattern CIP 1 . 
     A protective layer PRL surrounding the first sensor part SP 1  and the second sensor part SP 2  may be provided. The protective layer PRL may surround the upper surface, lower surface, and sidewalls of each of the first sensor part SP 1  and the second sensor part SP 2 . It is possible to prevent the first sensor part SP 1  and the second sensor part SP 2  from being damaged or deformed from external impact by the protective layer PRL. The protective layer PRL may include, for example, a transparent insulating material such as polyimide. The substrate SUB may surround sidewalls and a lower surface of the protective layer PRL. The upper surface of the protective layer PRL may be exposed by the substrate SUB. As another example, the upper surface of the protective layer PRL may be covered by the substrate SUB. 
     The first sensor part SP 1  and the second sensor part SP 2  may have a vertically symmetrical structure and a horizontally symmetrical structure, respectively. In other words, the first sensor part SP 1  and the second sensor part SP 2  may have a symmetric structure in each of the first direction D 1 , the second direction D 2 , and the third direction D 3 . 
     The level of each upper surface of first electrode patterns EP 1 , first wiring patterns IP 1 , first portions CIP 1   a  of first connection pattern CIP 1 , the second electrode patterns EP 2 , second wiring patterns IP 2 , and second connection patterns CIP 2  may be a first level LV 1 . That is, the level of each upper surface of first electrode patterns EP 1 , first wiring patterns IP 1 , first portions CIP 1   a  of first connection pattern CIP 1 , the second electrode patterns EP 2 , second wiring patterns IP 2 , and second connection patterns CIP 2  may be located at substantially the same level as each other. For example, the level of the upper surface of the first connection electrode CEP 1  may be the first level LV 1 . As another example, the level of the upper surface of the first connection electrode CEP 1  may be different from the first level LV 1 . 
     The level of the uppermost surface of the second connection electrode CEP 2  may be the second level LV 2 . The second level LV 2  may be located at a level higher than the first level LV 1 . That is, the uppermost surface of the second connection electrode CEP 2  may be located at a level higher than each of the upper surfaces of the first electrode patterns EP 1 , the first wiring patterns IP 1 , the first portions CIP 1   a  of the first connection pattern CIP 1 , the second electrode patterns EP 2 , the second wiring patterns IP 2 , the second connection patterns CIP 2 , and the first connection electrode CEP 1 . For example, the level of the uppermost surface of the second portion CIP 1   b  of the first connection pattern CIP 1  may be located at the second level LV 2 . As another example, the level of the uppermost surface of the second portion CIP 1   b  of the first connection pattern CIP 1  may be different from the level of the second level LV 2 . 
     The lowermost surface of each of the first electrode patterns EP 1 , the first wiring patterns IP 1 , the first connection patterns CIP 1 , the second electrode patterns EP 2 , the second wiring patterns IP 2 , and the second connection patterns field CIP 2  and the lowermost surface of the second connection electrode CEP 2  may be located at the same level. 
     Since the transparent conductive oxide is mostly composed of a brittle material, when wiring patterns have a straight structure, their flexibility may be deteriorated. According to embodiments of the inventive concept, the first wiring patterns IP 1 , the second wiring patterns IP 2 , the first connection patterns CIP 1 , and the second connection patterns CIP 2  including the transparent conductive oxide may have a serpentine structure. That is, as wiring patterns connecting adjacent electrode patterns have a serpentine structure, their flexibility may be improved. As a result, the touch recognition capability of the flexible touch panel may be improved. In addition, since the first sensor part SP 1  and the second sensor part SP 2  have a structure symmetric to each other left and right and up and down, respectively, when the flexible touch panel  10  is bent, mechanical reliability may be improved. As will be described later, the first sensor part SP 1  and the second sensor part SP 2  excluding the first connection electrode CEP 1  may be simultaneously formed using a photolithography process by etching the preliminary electrode layer. Accordingly, it is possible to implement fine patterns compared to the printing process. As a result, a touch panel having a high resolution may be provided. 
       FIGS.  7 ,  9 ,  11  and  13    are for explaining a method of manufacturing a flexible touch panel according to embodiments of the inventive concept, and are respectively enlarged plan views of area N of  FIG.  2   .  FIGS.  8 ,  10 ,  12 A, and  14 A  are cross-sectional views taken along line A-A′ of  FIGS.  7 ,  9 ,  11 , and  13   , respectively.  FIGS.  12 B and  14 B  are cross-sectional views taken along line B-B′ of  FIGS.  11  and  13   , respectively. 
     Referring to  FIGS.  7  and  8   , a carrier substrate PST may be provided. The carrier substrate PST may include, for example, glass. A first preliminary protective layer PPL 1  may be formed on an entire surface of the carrier substrate PST. The first preliminary protective layer PPL 1  may include, for example, polyimide. A preliminary connection electrode film (not shown) may be formed on the entire surface of the first preliminary protective layer PPL 1 . For example, the preliminary connection electrode film may include a transparent conductive oxide such as ITO. After a first mask pattern (not shown) is formed on the preliminary connection electrode film, the first connection electrode CEP 1  may be formed using this as an etching mask. The first connection electrode CEP 1  may be formed using a photolithography process. 
     Referring to  FIGS.  9  and  10   , an insulating layer ISL may be formed on the first connection electrode CEP 1 . The insulating layer ISL may include, for example, at least one of silicon oxide and silicon nitride. The insulating layer ISL may cover a portion of the first connection electrode CEP 1 . A portion of the first connection electrode CEP 1  may be exposed by the insulating layer ISL. The insulating layer ISL may also be formed using a photolithography process like the first connection electrode CEP 1 . 
     Referring to  FIGS.  11 ,  12 A, and  12 B , a preliminary electrode film (not shown) may be formed on the entire surface of the first preliminary protective layer PPL 1 . The preliminary electrode film may include, for example, a transparent conductive oxide such as ITO. The preliminary electrode film may cover the first connection electrode CEP 1  and the insulating layer ISL. After forming a second mask pattern (not shown) on the preliminary electrode film, a first sensor part SP 1  and a second sensor part SP 2  may be formed using this as an etching mask. In other words, the first connection patterns CIP 1  connected to the first connection electrode CEP 1 , the first electrode patterns EP 1  and first wiring patterns IP 1  of the first sensor pattern SR 1 , the second electrode patterns EP 2  and the second wiring patterns IP 2  of the second sensor pattern SR 2 , the second connection electrode CEP 2  on the insulating layer ISL, and the second connection patterns CIP 2  connected to the second connection electrode CEP 2  may be formed by etching the preliminary electrode film. The preliminary electrode film may be etched using a photolithography process. That is, the first sensor part SP 1  and the second sensor part SP 2  excluding the first connection electrode CEP 1  may be simultaneously formed. 
     Although not shown in the drawing, the external connection electrode CNP described with reference to  FIG.  1    may also be formed in the process of etching the preliminary electrode film. 
     According to embodiments of the inventive concept, the first sensor part SP 1  and the second sensor part SP 2  may be simultaneously formed using a photolithography process. That is, it may be easier to implement fine patterns compared to forming the patterns using a printing process. As a result, the manufacturing process is simplified and a touch panel having a higher resolution may be provided. 
     The level of each upper surface of first electrode patterns EP 1 , first wiring patterns IP 1 , first portions CIP 1   a  of first connection pattern CIP 1 , the second electrode patterns EP 2 , second wiring patterns IP 2 , and second connection patterns CIP 2  may be a first level LV 1 . The level of the uppermost surface of the second connection electrode CEP 2  may be the second level LV 2 . The second level LV 2  may be located at a level higher than the first level LV 1 . For example, the uppermost surface of the second portion CIP 1   b  of the first connection pattern CIP 1  may be located at the second level LV 2 . 
     The lowermost surface of each of the first electrode patterns EP 1 , the first wiring patterns IP 1 , the first connection patterns CIP 1 , the second electrode patterns EP 2 , the second wiring patterns IP 2 , and the second connection patterns field CIP 2  and the lowermost surface of the second connection electrode CEP 2  may be located at the same level. 
     The first connection patterns CIP 1 , the first electrode patterns EP 1 , and the first wiring patterns IP 1  may be integrally connected to each other. In other words, an interface may not be visible between the first connection patterns CIP 1 , the first electrode patterns EP 1 , and the first wiring patterns IP 1 . 
     The first connection electrode CEP 1  and the first connection patterns CIP 1  may not be integrally formed with each other. In other words, an interface may be visible between the first connection electrode CEP 1  and the first connection patterns CIP 1 . 
     The second connection electrode CEP 2 , the second connection patterns CIP 2 , the second electrode patterns EP 2 , and the second wiring patterns IP 2  may be integrally connected to each other. In other words, an interface may not be visible between the second connection electrode CEP 2 , the second connection patterns CIP 2 , the second electrode patterns EP 2 , and the second wiring patterns IP 2 . 
     Referring to  FIGS.  13 ,  14 A, and  14 B , a second preliminary protective layer PPL 2  may be formed on the entire surface of the first preliminary protective layer PPL 1 . The second preliminary protective layer PPL 2  may include the same material as the first preliminary protective layer PPL 1 . For example, the second preliminary protective layer PPL 2  may include polyimide. The second preliminary protective layer PPL 2  may cover the first sensor part SP 1  and the second sensor part SP 2 . 
     A third mask pattern (not shown) may be formed on the second preliminary protective layer PPL 2 . The second preliminary protective layer PPL 2  and the first preliminary protective layer PPL 1  may be etched using the third mask pattern as an etching mask. As a result, the protective layer PRL may be formed. The protective layer PRL may surround the upper surface, lower surface, and sidewalls of each of the first sensor part SP 1  and the second sensor part SP 2 . The protective layer PRL may be formed by etching the first preliminary protective layer PPL 1  and the second preliminary protective layer PPL 2  to correspond to the shapes of the first sensor part SP 1  and the second sensor part SP 2 . A portion of the carrier substrate PST may be exposed by the protective layer PRL. 
       FIGS.  15  and  16    are cross-sectional views for explaining a method of manufacturing a flexible touch panel according to embodiments of the inventive concept. Specifically,  FIGS.  15  and  16    are cross-sectional views for explaining a process of transferring the first sensor part SP 1  and the second sensor part SP 2  onto the substrate SUB. 
     Referring to  FIG.  15   , an adhesive film PUF may be formed on the resultant product described with reference to  FIGS.  13 ,  14 A and  14 B . That is, the adhesive film PUF may be formed on the protective layer PRL. Thereafter, the carrier substrate PST may be detached using a laser lift-off process. 
     Referring to  FIG.  16   , after turning over the result of  FIG.  15   , a substrate SUB may be formed. The substrate SUB may include a flexible material. For example, the substrate SUB may include an elastomer such as rubber. The substrate SUB may be formed using a casting process. Although not shown, a frame FR surrounding the protective layer PRL may be formed in a planar manner (see  FIG.  1   ). For example, the substrate SUB may be formed using a casting process using the adhesive film PUF and the frame FR as casting molds. That is, the substrate SUB may be finally formed by pouring a flexible material such as liquefied elastomer on the protective layer PRL, hardening the resultant product, and removing the adhesive film PUF. 
     As another example, after removing the adhesive film PUF, the elastomer may be additionally coated. Accordingly, the upper surface, lower surface, and sidewalls of the protective layer PRL may be surrounded by the substrate SUB. 
     According to embodiments of the inventive concept, the first wiring patterns, the second wiring patterns, the first connection patterns, and the second connection patterns including the transparent conductive oxide may have a serpentine structure. That is, flexibility may be improved because wiring patterns connecting adjacent electrode patterns have a serpentine structure. As a result, the touch recognition capability of the flexible touch panel may be improved. 
     Although the embodiments of the inventive concept have been described, it is understood that the inventive concept should not be limited to these embodiments but various changes and modifications may be made by one ordinary skilled in the art within the spirit and scope of the inventive concept as hereinafter claimed.