KR101925305B1 - Method for forming conducting polymer electrode containing metal nano particle and the etching liquid - Google Patents

Abstract

According to another embodiment of the present invention, there is provided a method of forming a transparent electrode, comprising: coating a metal nanowire on a surface of a substrate; Laminating a dry film resist (DFR) on the metal nanowire; Placing a mask having a pattern on the photosensitive film and exposing the mask; And etching the substrate surface with an etchant, wherein the etchant comprises 40 wt% to 60 wt% phosphoric acid (H ₃ PO ₄ ) and 6 wt% to 12 wt% nitric acid (HNO ₃ ).
The etching solution according to an embodiment includes 40 wt% to 6 wt% phosphoric acid (H ₃ PO ₄ ), 6 wt% to 12 wt% nitric acid (HNO ₃ ), and a solvent.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for forming a conductive polymer electrode containing metal nanoparticles,

The present invention relates to a method for forming a conductive polymer electrode containing metal nanoparticles and an etching solution.

2. Description of the Related Art In recent years, a touch panel has been applied to an image displayed on a display device in various electronic products by a method of touching an input device such as a finger or a stylus.

A display device, a solar cell, a touch panel, or the like is provided with an electrode for transferring electric charges or supplying electric power.

Indium tin oxide (ITO), which is the most widely used electrode, is expensive and requires high-temperature deposition and vacuum processing for electrode formation. In addition, it is physically easily hit by the bending and warping of the substrate, and the characteristics of the electrode are deteriorated, which makes it unsuitable for a flexible device.

In order to solve such problems, active researches on alternative electrodes are under way.

As a substitute electrode, a method of forming a transparent electrode using silver nanowires has been proposed. When a transparent electrode is formed using such a silver nanowire, a patterning process is required on the transparent electrode.

However, in the case of the silver nanowire, there is a problem that it is difficult to perform patterning such as an etching process because an overcoat material for protecting the silver nanowire is applied.

Accordingly, there is a need for a method of forming an etchant and a transparent electrode that can increase the efficiency of the etching process when the transparent electrode is formed using the silver nanowire.

The embodiments of the present invention provide a method of forming a transparent electrode using an etchant with more accurate pattern formation and higher efficiency and an etchant when a transparent electrode is formed on a substrate using silver nanowires.

According to another embodiment of the present invention, there is provided a method of forming a transparent electrode, comprising: coating a metal nanowire on a surface of a substrate; Laminating a dry film resist (DFR) on the metal nanowire; Placing a mask having a pattern on the photosensitive film and exposing the mask; And etching the substrate surface with an etchant, wherein the etchant comprises 40 wt% to 60 wt% phosphoric acid (H ₃ PO ₄ ) and 6 wt% to 12 wt% nitric acid (HNO ₃ ).

The etching solution according to an embodiment includes 40 wt% to 6 wt% phosphoric acid (H ₃ PO ₄ ), 6 wt% to 12 wt% nitric acid (HNO ₃ ), and a solvent.

The embodiment can etch the transparent electrode using an etchant containing phosphoric acid and nitric acid. In addition, the phosphoric acid (H ₃ PO ₄ ) is contained in an amount of more than 40 wt% to less than 60 wt% with respect to the total etching solution, and the nitric acid (HNO ₃ ) is contained in an amount of more than 6 wt% to less than 12 wt% .

When the transparent electrode pattern including silver nanowires is formed using the etching solution, etching can be performed at an accurate pattern interval. Also. Since the transparent electrode is formed using the silver nanowire that can replace the conventional indium tin oxide, the process cost can be reduced.

In addition, the etchant may include acetic acid capable of improving the etching rate, thereby improving the efficiency of the etching process.

1 is a process flow chart of a method of forming a transparent electrode according to an embodiment.
Figures 2 to 4 are scanning electron micrograph (SEM) photographs of a patterned transparent electrode according to an embodiment.

In the description of the embodiments, it is to be understood that each layer (film), area, pattern or structure may be referred to as being "on" or "under / under" Quot; includes all that is formed directly or through another layer. The criteria for top / bottom or bottom / bottom of each layer are described with reference to the drawings.

The thickness or the size of each layer (film), region, pattern or structure in the drawings may be modified for clarity and convenience of explanation, and thus does not entirely reflect the actual size.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a process flow chart of an electrode forming method according to an embodiment.

Referring to FIG. 1, an electrode forming method according to an embodiment includes a coating step (ST10), a laminating step (ST20), an exposure step (ST30), and an etching step (ST40).

In the coating step (ST10), a metal nanowire ink may be coated on the surface of the substrate. Preferably, the metal nanowire ink comprises silver nanowires. Further, the substrate may include a glass substrate.

In the step of coating the silver nanowires on the substrate, a slot-die coating method may be used. The slot die is a kind of coating method, and liquid fluid having flow is supplied to the space between upper and lower mold plates designed and processed inside the mold by a rheology called a slot die, Refers to a method of coating a fluid on a substrate in a uniform and uniform thickness in the width direction of the traveling direction.

However, the embodiment is not limited in any way, and the silver nanowires may be coated on the substrate by various coating methods such as spin coating, flow coating, dip coating and roll coating .

Next, in the laminating step ST20, a photosensitive film may be laminated on the silver nanowire-coated substrate surface.

In the pattern forming method according to the embodiment, a dry film resist (DFR) is used to form a pattern on the glass substrate. Methods for applying the pattern may include a dry film resist method and a photoresist method.

The photosensitive film may include various types, but it is preferable to use an acrylic type photosensitive film such as an acrylate copolymer resin which is not oxidized or decomposed by an etching solution in the etching process. As the acrylic type photosensitive film, a commercially available product can be used.

In the step of laminating the photosensitive film, the photosensitive film may be laminated on the surface of the substrate and passed through a heated roller. At this time, the roller should be heated to a sufficient temperature of 100 ° C or more so that the laminated photosensitive film and the substrate are not separated. When the photosensitive film is separated from the glass substrate, the etching solution penetrates into portions other than the portion where the pattern is to be formed on the surface in the etching process, so that a pattern of a desired shape can not be formed on the substrate.

Subsequently, in the step of exposing (ST30), the substrate on which the photosensitive film is laminated can be exposed. That is, a mask having a pattern formed thereon may be placed on the photosensitive film, and an exposure pattern may be formed using a UV exposure apparatus.

Subsequently, in the step of etching (ST40), the substrate may be etched to form a pattern on the substrate. That is, a pattern to be implemented can be formed on the surface of the substrate using an etchant.

The etching solution may comprise phosphoric acid (H ₃ PO _4), nitric acid (HNO ₃₎ and a solvent. Or the etchant may further comprise acetic acid together with phosphoric acid and nitric acid.

The phosphoric acid serves to facilitate oxide removal and nitric acid penetration on the substrate. In addition, the phosphoric acid may be contained in an amount of 40% by weight to 60% by weight with respect to the whole etching solution. If the phosphoric acid content is less than 40 wt%, etching with the etchant may not be performed. If the phosphoric acid content exceeds 60 wt%, the degree of acidification may be high, and mixing of the phosphoric acid with nitric acid or acetic acid may be difficult.

The nitric acid is capable of etching substantial silver nanowires. That is, the silver nanowires coated on the substrate can be etched by the following reaction formula.

(Scheme)

_{3Ag + 4HNO 3 → 3AgNO 3 +} 2H 2 0 + NO

The nitric acid may be included in an amount of 6 wt% to 12 wt% with respect to the entire etching solution. When the amount of nitric acid is less than 6% by weight, etching with the etching solution may not be performed. When the amount of nitric acid is more than 12% by weight, acidity of the nitric acid is high and mixing of the phosphoric acid with nitric acid or acetic acid may be difficult.

The acetic acid can control the rate of the etching process. That is, the nitrate controls the pH of the etching process according to the amount of acetic acid. Preferably, the acetic acid may be contained in an amount of not more than 6% by weight based on the entire etching solution.

The etchant may be applied on the substrate in a spray manner.

The etchant may be applied at a temperature of 35 ° C to 50 ° C. The etching solution may be applied at a pressure of 1 kg / cm 2 to 2 kg / cm 2. If the etchant is 50 ° C or higher, the etchant can not be etched because the etchant may boil.

Conventionally, indium tin oxide (ITO) was used as a composition for forming the transparent electrode. However, the indium tin oxide has a problem in that the transparent electrode is expensive due to the indium. In order to replace this, silver nanowires were used as a composition for forming the transparent electrode. The silver nanowire has a problem in that it is difficult to fix the patterning due to the application of an overcoating material for protecting the silver nanowire.

Accordingly, in the method of forming a transparent electrode according to the embodiment, the etching liquid containing phosphoric acid and nitric acid can be used in the patterning step. Preferably, the etchant may comprise 40 wt% to 60 wt% phosphoric acid and 6 wt% to 12 wt% nitric acid. More preferably, the etching solution may further include an acidic solution such as acetic acid.

FIGS. 2 to 4 are scanning electron micrographs of the transparent electrode patterned by the transparent electrode forming method of the embodiment.

Fig. 2 shows that the interval between the DFR patterns is 20 占 퐉, Fig. 3 shows the interval between the DFR patterns is 30 占 퐉, and Fig. 4 shows the interval between the DFR patterns is 40 占 퐉.

Referring to FIGS. 2 to 4, it can be seen that the interval between the DFR patterns is substantially similar to the width of the transparent electrode pattern.

Accordingly, when the transparent electrode pattern including the silver nanowire is formed using the etching solution according to the embodiment, the etching can be performed at an accurate pattern interval. Also. Since the transparent electrode is formed using the silver nanowire that can replace the conventional indium tin oxide, the process cost can be reduced.

In addition, the etchant includes acetic acid capable of improving the etching rate, thereby improving the efficiency of the etching process.

The transparent electrode formed by such a manufacturing method can be used for a touch panel, a touch window, etc., in which a transparent electrode is required.

Hereinafter, the present invention will be described in more detail with reference to Table 1. However, it is to be understood that the present invention is not limited thereto.

Temperature Phosphoric acid (wt%) Nitric acid (wt.%) Time (sec) DFR measured value (탆) Transparent electrode pattern width (占 퐉) 35 40 6 No etching
35

40

12
60 70 69.71 90 60 56.72 120 50 50.87 35 60 12 High risk due to high etchant pH

35


60


6
30 70 71.53 60 50 49.69 90 50 45.02 120 30 28.02

35


50


9

30 40 36.5 60 40 40.8 90 30 30.3 120 20 21.1
40

40

12
60 50 44.98 90 40 40.87 120 30 27.8 40 60 12 High risk due to high etchant pH

40



60


6 30 40 39.95 60 30 28.65 90 20 22.65 120 20 20.28

40



50


9
30 30 28.1 60 30 28.5 90 30 39.1 120 20 21.8 40 40 6 120 80 87.58

Referring to Table 1, it can be seen that in the method of forming a transparent electrode according to the embodiment, the pattern formation efficiency varies depending on the composition of the etchant and the etching time. That is, when the phosphoric acid is more than 40% by weight and less than 60% by weight and the nitric acid is more than 6% by weight and less than 12% by weight, patterning similar to that of the DFR is observed.

When the phosphoric acid content is 40 wt% and the nitric acid content is 6 wt%, it can be understood that no etching is performed.

When the phosphoric acid is contained in an amount of 60 wt% or more, the pH of the etching solution is too low, that is, the acidity is too high, so that the risk during the etching process may be very high irrespective of the temperature of the etching solution.

The features, structures, effects and the like described in the above-mentioned embodiments are included in at least one example of actual assembly of the present invention, and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Claims (13)

Coating a transparent electrode comprising a silver nanowire on the substrate surface and an overcoating material for protecting the silver nanowire;
Laminating a dry film resist (DFR) on the silver nanowire;
Placing a mask having a pattern on the photosensitive film and exposing the mask to form a photosensitive pattern; And
Etching the substrate surface using an etchant,
The etching solution includes phosphoric acid, nitric acid, and acetic acid,
The phosphoric acid is contained in an amount of more than 40 wt% to less than 60 wt% with respect to the whole of the etchant,
The nitric acid is contained in an amount of more than 6 wt% to less than 12 wt% with respect to the whole etching solution,
Wherein the acetic acid is contained in an amount of 6 wt% or less with respect to the total etching solution. The method according to claim 1,
The spacing between the photosensitive patterns was 20 占 퐉,
Wherein the line width of the transparent electrode pattern formed by the etching step is 18.1 占 퐉 to 25.3 占 퐉. The method according to claim 1,
The interval between the photosensitive patterns was 30 mu m,
Wherein the line width of the transparent electrode pattern formed by the etching step is 28.9 占 퐉 to 32.2 占 퐉. The method according to claim 1,
The interval between the photosensitive patterns was 40 mu m,
Wherein the line width of the transparent electrode pattern formed by the etching step is 35.2 占 퐉 to 39.6 占 퐉. The method according to claim 1,
Wherein the line width of the transparent electrode pattern formed by the etching step is 20 占 퐉 to 87.58 占 퐉. The method according to claim 1,
Wherein the etching step is etched at a temperature of 35 DEG C to 50 DEG C. The method according to claim 1,
Wherein the etching step is performed at a pressure of 1 kg / cm 2 to 2 kg / cm 2. A transparent electrode produced by the method for forming a transparent electrode according to any one of claims 1 to 7. A touch window comprising a transparent electrode made by the method of forming a transparent electrode according to any one of claims 1 to 7. delete delete delete delete

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