Electrode pattern structure, method of fabricating the same and touch sensor including the same

Abstract

The electrode pattern structure of the embodiments of the present invention comprises a substrate, an organic intermediate layer formed on the substrate, and an electrode pattern disposed on the organic intermediate layer and comprising a conductive polymer and a metal nanowire. The organic intermediate layer prevents delamination of the electrode pattern and can improve chemical and mechanical stability.

Description

Technology Field

[0001] The present invention relates to an electrode pattern structure, a method for manufacturing the same, and a touch sensor including the same. More specifically, the invention relates to an electrode pattern structure including a metal nanowire, a method for manufacturing the same, and a touch sensor including the same. Background Technology

[0002] For example, in the case of sensor devices such as touch sensors, low-resistance sensing electrodes are included to improve sensing sensitivity and sensing speed. As the touch sensor is recently integrated into display devices such as smartphones, it is necessary to improve the transparency of the sensing electrodes.

[0003] Furthermore, with the development of flexible display devices capable of folding or bending, the sensing electrodes of touch sensors also need to possess enhanced flexibility. However, sensing electrodes formed from conventional metal patterns, indium tin oxide (ITO) patterns, etc., may exhibit mechanical defects such as cracking during severe bending operations.

[0004] For example, as disclosed in Korean Patent Publication No. 10-2018-0099987, electrodes containing silver nanowires are being studied. However, in the case of silver nanowires, it is not easy to pattern them into a predetermined electrode shape. In addition, problems such as electrode peeling and damage may occur due to the unit processes involved in the electrode patterning process. Prior art literature

[0005] Korean Patent Publication No. 10-2018-0099987 The problem to be solved

[0006] One objective of the present invention is to provide an electrode pattern structure having improved electrical and mechanical properties.

[0007] One objective of the present invention is to provide a method for manufacturing an electrode pattern structure having improved electrical and mechanical properties.

[0008] One objective of the present invention is to provide a touch sensor comprising an electrode pattern structure having improved electrical and mechanical properties. means of solving the problem

[0009] 1. A substrate; an organic intermediate layer formed on the substrate; and an electrode pattern structure comprising an electrode pattern disposed on the organic intermediate layer and comprising a conductive polymer and a metal nanowire.

[0010] 2. The electrode pattern structure of 1 above, wherein the organic intermediate layer comprises a thermosetting or UV-curable resin comprising at least one of an epoxy resin, an acrylic resin, or a melamine resin.

[0011] 3. The electrode pattern structure according to 1, wherein the organic intermediate layer comprises a transparent coating layer comprising at least one of the polyorganosiloxane-based resin, polyimide-based resin, or polyurethane-based resin.

[0012] 4. An electrode pattern structure according to 1 above, wherein the conductive polymer layer comprises PEDOT-PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)) and the metal nanowire comprises silver nanowire.

[0013] 5. A method for manufacturing an electrode pattern structure, comprising: a step of forming an organic intermediate layer on a substrate; a step of forming a preliminary electrode layer comprising a conductive polymer and a metal nanowire on the organic intermediate layer; a step of forming a photoresist layer on the preliminary electrode layer; a step of forming a photoresist pattern by partially removing the photoresist layer using a developer; and a step of partially removing the preliminary electrode layer through a wet etching process using the photoresist pattern as a mask.

[0014] 6. A method for manufacturing an electrode pattern structure according to 5 above, wherein the developer comprises an ammonium salt-based base solution.

[0015] 7. A method for manufacturing an electrode pattern structure according to 5, wherein the wet etching process comprises supplying an acidic etchant to the pre-electrode layer, the acidic etchant comprising at least one selected from the group consisting of phosphoric acid, nitric acid, hydrochloric acid, hydrogen peroxide, and acetic acid.

[0016] 8. A method for manufacturing an electrode pattern structure, wherein the step of forming the photoresist pattern in 5 above comprises immersing the substrate on which the photoresist layer and the pre-electrode layer are formed in the developer solution for 60 seconds or more.

[0017] 9. A method for manufacturing an electrode pattern structure, wherein the step of forming the preliminary electrode layer in 5 above comprises directly applying a conductive composition comprising the conductive polymer and the metal nanowire onto the organic intermediate layer.

[0018] 10. A touch sensor comprising an electrode pattern structure of any one of 1 to 4 above. Effects of the invention

[0019] An electrode pattern structure according to embodiments of the present invention comprises a conductive polymer and a metal nanowire and may have enhanced flexibility and electrical conductivity. According to exemplary embodiments, an electrode layer may be formed by forming an organic intermediate layer on a substrate and applying a conductive composition comprising the conductive polymer and the metal nanowire onto the organic intermediate layer.

[0020] The adhesion of the electrode layer is improved by the organic intermediate layer, thereby improving chemical resistance and peel resistance against the developer, etchant, etc. used during the electrode layer patterning process. Brief explanation of the drawing

[0021] FIG. 1 is a schematic cross-sectional view showing an electrode pattern structure according to exemplary embodiments. FIGS. 2 to 6 are schematic cross-sectional views illustrating a method for manufacturing an electrode pattern structure according to exemplary embodiments. Figure 7 is an image of the electrode pattern structure of the embodiment after development and etching. Figures 8 and 9 are images of the electrode pattern structure of the comparative example after development and etching. Specific details for implementing the invention

[0022] Embodiments of the present invention provide an electrode pattern structure comprising a substrate, an organic intermediate layer, and an electrode pattern comprising a metal nanowire / conductive polymer. Additionally, embodiments of the present invention provide a touch sensor comprising said electrode pattern structure.

[0023] Embodiments of the present invention will be described in more detail below with reference to the drawings. However, the following drawings attached to this specification are intended to illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the aforementioned description; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0024] FIG. 1 is a schematic cross-sectional view showing an electrode pattern structure according to exemplary embodiments.

[0025] Referring to FIG. 1, the electrode pattern structure may include a substrate (100), an organic intermediate layer (110), and an electrode pattern (130).

[0026] The term "substrate (100)" is used to encompass a support layer, an interlayer insulating layer, or a film-type substrate for forming an organic intermediate layer (110) and an electrode pattern (130). For example, the substrate (100) may be a film material commonly used in touch sensors without special limitations, and may include, for example, glass and / or a transparent flexible polymer material. Examples of the transparent flexible polymer include cyclic olefin polymer (COP), polyethylene terephthalate (PET), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyallylate, polyimide (PI), cellulose acetate propionate (CAP), polyethersulfone (PES), cellulose triacetate (TAC), polycarbonate (PC), cyclic olefin copolymer (COC), polymethyl methacrylate (PMMA), etc. Examples of the above-mentioned inorganic insulating materials include silicon oxide, silicon nitride, silicon oxynitride, metal oxide, etc.

[0027] In some embodiments, a layer or film member of an image display device into which the touch sensor is inserted may be provided as a substrate (100). For example, an encapsulation layer or passivation layer included in a display panel may be provided as a substrate (100).

[0028] An organic intermediate layer (110) may be formed on the upper surface of a substrate (100). According to exemplary embodiments, the organic intermediate layer (110) may include an epoxy resin, an acrylic resin, a melamine resin, etc. formed through heat curing or UV curing. The organic intermediate layer (110) may also include a transparent coating layer using a siloxane resin (polyorganosiloxane) such as polydimethylsiloxane (PDMS), a polyimide resin, a polyurethane resin, etc.

[0029] The electrode pattern (130) may be in direct contact with the upper surface of the organic intermediate layer (110). According to exemplary embodiments, the electrode pattern (130) may comprise a conductive polymer and a metal nanowire mixed with said conductive polymer. In one embodiment, said metal nanowire may comprise a silver (Ag) nanowire. That metal nanowire may be substantially uniformly mixed with said conductive polymer and distributed uniformly over the entire area of ​​the electrode pattern (130).

[0030] As the conductive polymer mentioned above, materials commercially available in the display and sensor fields may be used without special limitations. In one embodiment, the conductive polymer may include PEDOT-PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)).

[0031] The electrode pattern (130) may include a plurality of island patterns that are each physically separated from one another. For example, each electrode pattern (130) may have a polygonal pattern shape such as a rhombus shape. In some embodiments, the electrode pattern (130) may include a plurality of line patterns.

[0032] In some embodiments, the thickness of the electrode pattern (130) may be about 20 to 500 nm, preferably about 30 to 200 nm. The sheet resistance of the electrode pattern (130) may be about 100 Ω / □ or less, for example, about 10 to 100 Ω / □.

[0033] In some embodiments, the electrode pattern structure may have a light transmittance of about 85% or more.

[0034] According to the exemplary embodiments described above, an organic intermediate layer (110) may be formed between the electrode pattern (130) and the substrate (100) to support the electrode pattern (130). For example, the resin material described above included in the organic intermediate layer (110) may be bonded with a high affinity to the conductive polymer and / or binder resin included in the electrode pattern (130).

[0035] Accordingly, an electrode pattern structure having improved chemical and mechanical stability can be obtained, which prevents the electrode pattern (130) from being damaged or peeled off by the developer, etchant, etc. used in the etching process for forming the electrode pattern (130).

[0036] In addition, even when the electrode pattern structure is bent or curved, the electrode pattern (130) is supported by the organic intermediate layer (110), so the detachment of the electrode pattern (130) can be prevented. Therefore, the flexible characteristics of the electrode pattern structure can also be improved.

[0037] FIGS. 2 to 6 are schematic cross-sectional views illustrating a method for manufacturing an electrode pattern structure according to exemplary embodiments.

[0038] Referring to FIG. 2, an organic intermediate layer (110) can be formed on a substrate (100). For example, a thermosetting or UV-curable composition including an epoxy monomer, an acrylic monomer, a melanin monomer, etc., can be applied to the upper surface of the substrate (100) through a spin coating process, a slit coating process, a printing process, etc. Afterward, the organic intermediate layer (110) can be formed through a curing process. The organic intermediate layer (110) may also be formed by applying a varnish-type composition including a siloxane resin, a polyimide resin, a polyurethane resin, etc., and then through a drying process.

[0039] Referring to FIG. 3, a preliminary electrode layer (120) can be formed on an organic intermediate layer (110). According to exemplary embodiments, the preliminary electrode layer (120) may include metal nanowires dispersed within a conductive polymer.

[0040] For example, a conductive composition in the form of ink can be formed by dispersing a conductive polymer such as PEDOT-PSS and silver nanowires in water or an alcohol-based solvent. The conductive composition may further include a binder resin for improving dispersibility, such as polyvinylpyrrolidone (PVP), polyvinylacetal (PVA), or polyvinylbutyral (PVB).

[0041] In exemplary embodiments, the content of the conductive polymer and the metal nanowire may be included in an amount of 0.1 to 1 weight% each with respect to the total weight of the conductive composition. Within this range, the visibility of the electrode pattern (130) can be prevented, and the adhesion to the organic intermediate layer (110), the conductivity of the electrode pattern (130), and the dispersibility of the metal nanowire in the composition can be improved.

[0042] The average diameter of the silver nanowires included in the conductive composition may be about 1 to 50 nm, preferably about 1 to 20 nm. The average length of the silver nanowires may be about 10 µm or more, preferably about 15 to 40 µm.

[0043] For example, the above conductive composition can be formed on an organic intermediate layer (110) through a coating process such as a spin coating process, and then a pre-electrode layer (120) can be formed through a drying process.

[0044] Referring to FIG. 4, a photoresist layer (140) can be formed on a pre-electrode layer (120). Subsequently, the photoresist layer (140) can be exposed to light to form an exposed portion (142) and a non-exposed portion (145).

[0045] In one embodiment, when the photoresist layer (140) is formed from a negative type photoresist composition, additional crosslinking is induced in the exposure portion (142), so that the solubility of the developer may be reduced compared to the non-exposure portion (145).

[0046] Referring to FIG. 5, either the exposed portion (142) or the unexposed portion (145) can be selectively removed through a developing process.

[0047] For example, as described above, when a photoresist layer (140) is formed using a negative type photoresist composition, the non-exposed portion (145) can be removed by a development process. In this case, a photoresist pattern (144) can be defined by the remaining exposed portion (142).

[0048] In contrast, when a photoresist layer (140) is formed using a positive type photoresist composition, the exposed portion (142) may be removed by a development process.

[0049] The above development process may be performed using a developer having strong basicity, such as an ammonium salt-based solution (e.g., tetramethylammonium hydroxide (TMAH)). For example, it may be performed by immersing a substrate having a photoresist layer (140) formed thereon in the developer for a predetermined amount of time. The immersion time may be, for example, 30 seconds or more, 60 seconds or more, 90 seconds or more, or 120 seconds or more.

[0050] According to exemplary embodiments, an organic intermediate layer (110) may be formed below the preliminary electrode layer (120). The organic intermediate layer (110) contacts the bottom surface of the preliminary electrode layer (120) and may function as an adhesive layer to fix the preliminary electrode layer (120).

[0051] Therefore, the above developer can prevent the shrinkage of the conductive polymer, peeling of the preliminary electrode layer (120), and lifting of the preliminary electrode layer (120) by penetrating into the interior of the preliminary electrode layer (120) or the bottom surface of the preliminary electrode layer (120).

[0052] In addition, since sufficient developer immersion time can be secured, the resolution of the photoresist pattern (144) is improved, allowing for the high-reliability manufacturing of an electrode pattern (130) with a fine line width.

[0053] Referring to FIG. 6, an etchant solution can be supplied onto a pre-electrode layer (120) using a photoresist pattern (144) as a mask. According to exemplary embodiments, the etchant solution may be an acidic solution comprising phosphoric acid, nitric acid, hydrochloric acid, hydrogen peroxide, and / or acetic acid.

[0054] The above etchant solution can substantially remove the metal nanowires contained within the pre-electrode layer (120). For example, as the metal nanowires are removed, the conductive polymer can be removed along with them.

[0055] Accordingly, the portion of the preliminary electrode layer (120) included in the area where the photoresist layer (140) has been removed (e.g., the exposed portion) can be substantially removed. The remaining portion of the preliminary electrode layer (120) can be defined as the electrode pattern (130) described with reference to FIG. 1.

[0056] The photoresist pattern (144) remaining on the electrode pattern (130) can be removed, for example, through a stripping process and / or an ashing process.

[0057] The electrode pattern structure described above can be utilized as sensing electrodes of a touch sensor (including a fingerprint sensor), for example. For example, the electrode pattern (130) shown in FIG. 1 can be provided as a sensing electrode.

[0058] For example, the sensing electrodes may be a polygonal pattern arranged together on the same plane. Alternatively, the sensing electrodes may be distributed on the upper and lower surfaces of the substrate (100). In this case, a first organic intermediate layer and a second organic intermediate layer are formed on the upper and lower surfaces of the substrate (100), respectively, and the electrode patterns (130) described above may be distributed on the first organic intermediate layer and the second organic intermediate layer.

[0059] Experimental examples are presented below to aid in understanding the present invention; however, the following experimental examples are merely illustrative of the invention and do not limit the appended claims. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and spirit of the invention, and that such variations and modifications fall within the scope of the appended claims.

[0060] Experimental example

[0061] Examples

[0062] A polydimethylsiloxane (PDMS) coating was formed as an organic intermediate layer with a thickness of 2 μm on a COP substrate with a thickness of 40 μm. A pre-electrode layer comprising silver nanowires (AgNW, average diameter 20 nm, average length 20 μm) and PEDOT:PSS was formed on the organic intermediate layer, and a development process and a wet etching process using a TMAH solution and a phosphoric acid solution, respectively, were performed to form electrode patterns including rhombus patterns (thickness: 300 nm) with a side length of 2 mm, as described with reference to FIGS. 2 to 6.

[0063] Comparative example

[0064] In the example, an electrode pattern structure was manufactured using the same method, except that the organic intermediate layer was omitted and electrode patterns were formed directly on the COP substrate.

[0065] The occurrence of peeling of the electrode patterns was observed while changing the immersion time (development time) in the TMAH solution used in the development process of the electrode pattern structures of the examples and comparative examples. The results are listed in Table 1 below.

[0066] The evaluation results are shown in Table 1 below.

[0067] Phenomenon time 30 seconds 60 seconds 90 seconds 120 seconds Examples Mi-hyang-sang No peeling No peeling No peeling (see Fig. 7) Comparative example Mi-hyang-sang Electrode lifting, wrinkle formation (see Fig. 8) Partial electrode peeling (see Fig. 9) Full peeling

[0068] FIG. 7 is an image of the electrode pattern structure of the example after development and etching. FIG. 8 and FIG. 9 are images of the electrode pattern structure of the comparative example after development and etching.

[0069] Referring to Table 1 and Figures 7 to 9 above, in the case of the example, no electrode peeling was observed even when immersed in the developer for 120 seconds.

[0070] In the comparative example, wrinkles and lifting of some electrode patterns were observed at a development time of 60 seconds, and some of the electrode patterns were completely peeled off from the substrate as the development time exceeded 90 seconds. Explanation of the symbols

[0071] 100: Substrate 110: Organic intermediate layer 120: Preliminary electrode layer 130: Electrode pattern 140: Photoresist layer 142: Exposure section 144: Photoresist pattern 145: Non-exposed area

Claims

Claim 1 An electrode pattern structure comprising: a substrate; an organic intermediate layer formed on the substrate; and a plurality of electrode patterns disposed on the organic intermediate layer and comprising a conductive polymer including PEDOT-PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)) and a metal nanowire, wherein the organic intermediate layer is disposed between the substrate and the electrode patterns and the upper surface of the organic intermediate layer is exposed between adjacent electrode patterns. Claim 2 An electrode pattern structure according to claim 1, wherein the organic intermediate layer comprises a thermosetting or UV-curable resin comprising at least one of an epoxy resin, an acrylic resin, or a melamine resin. Claim 3 An electrode pattern structure according to claim 1, wherein the organic intermediate layer comprises a transparent coating layer comprising at least one of a polyorganosiloxane-based resin, a polyimide-based resin, or a polyurethane-based resin. Claim 4 The electrode pattern structure according to claim 1, wherein the metal nanowire comprises silver nanowires. Claim 5 A method for manufacturing an electrode pattern structure comprising: a step of forming an organic intermediate layer on a substrate; a step of forming a preliminary electrode layer comprising a conductive polymer including PEDOT-PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)) and a metal nanowire on the organic intermediate layer; a step of forming a photoresist layer on the preliminary electrode layer; a step of forming a photoresist pattern by partially removing the photoresist layer using a developer; and a step of forming a plurality of electrode patterns by partially removing the preliminary electrode layer through a wet etching process using the photoresist pattern as a mask, wherein the upper surface of the organic intermediate layer is exposed between adjacent electrode patterns. Claim 6 A method for manufacturing an electrode pattern structure according to claim 5, wherein the developer comprises an ammonium salt-based base solution. Claim 7 A method for manufacturing an electrode pattern structure according to claim 5, wherein the wet etching process comprises supplying an acidic etchant to the pre-electrode layer, the etchant comprising at least one selected from the group consisting of phosphoric acid, nitric acid, hydrochloric acid, hydrogen peroxide, and acetic acid. Claim 8 A method for manufacturing an electrode pattern structure according to claim 5, wherein the step of forming the photoresist pattern comprises immersing the substrate on which the photoresist layer and the pre-electrode layer are formed in the developer solution for 60 seconds or more. Claim 9 A method for manufacturing an electrode pattern structure according to claim 5, wherein the step of forming the preliminary electrode layer comprises directly applying a conductive composition comprising the conductive polymer and the metal nanowire onto the organic intermediate layer. Claim 10 A touch sensor comprising the electrode pattern structure of claim 1.

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