KR20100009309A - Method of fabricating electrode pattern and coductive ink compopsition used therein - Google Patents

Abstract

PURPOSE: A method for forming electrode pattern is provided to form electrode pattern having high conductivity without damage to substrate. CONSTITUTION: A method for forming electrode pattern comprises: a step of preparing a substrate; a step of forming electrode pattern on the substrate using conductive ink composition; and a step of heating the electrode pattern at 100 ~ 300°C. The conductive ink composition contains first metal nanoparticle and second metal nanoparticle of 2.31-3.09 of volume ratio in solvent.

Description

Method of fabricating electrode pattern and coductive ink compopsition used therein}

The present invention relates to a method of forming an electrode pattern and a conductive ink composition used therein, and more particularly, to an electrode pattern forming method and a conductive ink composition used to improve the filling density and conductivity of metal particles.

Various electronic devices such as active and passive devices, displays, solar cells, sensors, etc. are faced with demands for lightness, portability, and high impact resistance. Accordingly, a method of forming various electronic elements such as electrodes on a flexible substrate has been studied.

On the other hand, since flexible substrates are inferior in heat resistance compared with rigid substrates, such as glass, a low temperature process is required at the time of formation of each electronic element.

Although a method of forming a metal layer on a rigid substrate and forming an electrode pattern by a photolithography process has been generally used, this may damage a flexible substrate with a high temperature process, which is complicated and expensive. In addition, there is a risk of environmental pollution due to the discharge of gas, waste water, etc. during the exposure and etching process.

In addition, in order to form an electrode in a low temperature heat treatment method that does not damage the flexible substrate, a method of directly drawing a pattern by manufacturing a conductive polymer such as PEDOT / PSS (Poly (EthyleneDiOxyThiophene) / Poly (Styrene Sulfonic acid) in a liquid phase However, this has been a problem that the conductive polymer is less conductive than the metal.

Therefore, while using a low temperature process that does not damage the flexible substrate, it is necessary to form an electrode pattern excellent in conductivity.

The technical problem to be achieved by the present invention is to provide a method for forming an electrode pattern with improved packing density and conductivity of metal particles.

Another object of the present invention is to provide a conductive ink composition used in the electrode pattern forming method.

The technical problems of the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

Conductive ink composition according to an embodiment of the present invention for achieving the above technical problem, the first metal nanoparticles having a first average particle diameter, the second metal nanoparticles having a second average particle diameter of more than twice the first average particle diameter Including particles and a solvent, the volume ratio of the second metal nanoparticles and the first metal nanoparticles mixed in the solvent is 2.31 to 3.09.

In accordance with another aspect of the present invention, there is provided a method of forming an electrode pattern, the method comprising: providing a substrate; A second metal nanoparticle having a mean particle diameter and a solvent, wherein the volume ratio of the second metal nanoparticle and the first metal nanoparticle mixed in the solvent is 2.31 to 3.09 on the substrate using the conductive ink composition. Forming a shape of the electrode pattern at the bottom, and heat-treating the shape of the electrode pattern at a low temperature of 300 ° C. or less.

Other specific details of the invention are included in the detailed description and drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Thus, in some embodiments, well known process steps, well known device structures and well known techniques are not described in detail in order to avoid obscuring the present invention. Like reference numerals refer to like elements throughout.

The spatially relative terms " below ", " beneath ", " lower ", " above ", " upper " It may be used to easily describe the correlation of a device or components with other devices or components. Spatially relative terms are to be understood as including terms in different directions of the device in use or operation in addition to the directions shown in the figures. For example, when flipping a device shown in the figure, a device described as "below" or "beneath" of another device may be placed "above" of another device. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can also be oriented in other directions, so that spatially relative terms can be interpreted according to orientation.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, “comprises” and / or “comprising” refers to the presence of one or more other components, steps, operations and / or elements. Or does not exclude additions.

Unless otherwise defined, all terms used in the present specification (including technical and scientific terms) may be used in a sense that can be commonly understood by those skilled in the art. In addition, the terms defined in the commonly used dictionaries are not ideally or excessively interpreted unless they are specifically defined clearly.

Hereinafter, the conductive ink composition according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1A to 3. 1A to 1C are schematic diagrams showing the first and second metal particle sizes in the conductive ink composition according to the first embodiment of the present invention and the metal particle sizes of the conductive inks of the comparative example. 2 is a graph showing the packing bulk density of the conductive ink composition according to the first embodiment of the present invention in comparison with a comparative example. 3 is a graph showing the viscosity of the conductive ink composition according to the first embodiment of the present invention.

The conductive ink composition of this embodiment includes the first metal nanoparticles and the second metal nanoparticles mixed in a solvent.

Referring to FIG. 1A, the conductive ink composition 130 of the present embodiment includes first metal nanoparticles 110 and second metal nanoparticles 120 having different sizes.

The first metal nanoparticles 110 and the second metal nanoparticles 120 are provided in nanometer (nm) size. When the metal particles are provided in nanometer size, surface properties may be improved due to changes in electron and crystal structure or surface area of the particles. In particular, the nanoparticles have a reduced melting point compared to before the size of the crystals is reduced to nanometer size. Accordingly, the metal particles can be fused at low temperatures, which is useful for forming an electrode pattern requiring a low temperature process.

Meanwhile, the metal nanoparticles may be provided in a nanometer size, but the first metal nanoparticles 110 and the second metal nanoparticles 120 having different average particle diameters may be mixed to reduce the vacancy between the nanoparticles. use. For example, the second metal nanoparticle 120 may have a larger average particle diameter than the first metal nanoparticle 110. However, the second metal nanoparticle 120 does not exclude that the average particle diameter of the first metal nanoparticle 110 is large.

1B and 1C, the conductive ink composition 131 including only the first metal nanoparticles 110 except for the second metal nanoparticles 120 or the first metal nanoparticles 110 is excluded. The conductive ink composition 132 including only the second metal nanoparticles 120 may have a large void area.

The volume ratio of the second metal nanoparticles 120 and the first metal nanoparticles 110 is 2.31 to 3.09. In this volume ratio, the packing volume density of the second metal nanoparticles 120 and the first metal nanoparticles 110 is the highest, and the conductive ink including the first metal nanoparticles 110 and the second metal nanoparticles 120 is present. The conductivity of the electrode pattern formed using the composition 130 may be maximized.

Referring to FIG. 2, the packing bulk density of the conductive ink composition 131 including only the first metal nanoparticles 110 except for the second metal nanoparticles 120 (see (1) of FIG. 2) or The first metal nanoparticles 110 and the packing bulk density of the conductive ink composition 132 including only the second metal nanoparticles 120 except for the first metal nanoparticles 110 (see FIG. 2 (3)) and The packing bulk density (see (2-1), (2-2), and (2-3) of FIG. 2) of the conductive ink composition 130 including all of the second metal nanoparticles 120 is much higher. can confirm.

Looking at the porosity due to the mixing of the first metal nanoparticles 110 and the second metal nanoparticles 120, the first metal nanoparticles 110 that are relatively small with the second metal nanoparticles 120 that are relatively large. Of the second metal nanoparticles when the volume ratio of is 2: 1, 3: 1, and 4: 1, respectively (see (2-1), (2-2), and (2-3) of FIG. 2, respectively) When the volume ratio of 120 and the first metal nanoparticles 110 is 3: 1, it can be seen that the packing bulk density is the highest. 2 shows the packing bulk density with respect to the weight% of the first metal nanoparticles 110, but assuming that the first and second metal nanoparticles 110 and 120 each have a constant average particle diameter, the weight ratio is determined by volume ratio. Since the proportion is proportional to the volume ratio of the second and first metal nanoparticles 120 and 110 from FIG. 2.

Meanwhile, the arrangement of the particles mixed together with the first metal nanoparticles 110 and the second metal nanoparticles 120 may be a body-centered cubic structure or a face-centered cubic structure that is a regular filling arrangement in a single structure. It does not follow the Face Centered Cubic Structure, but rather the Furnas model, which is an irregular filling arrangement.

Theoretical maximum packing fraction, PF _MAX , in the Furnas model with relatively large and relatively small particles is given by

PF _MAX = PF _L + (1-PF _L ) PF _S ....... (Equation 1)

Here, PF _L is the filling rate of the system filled with only large particles, and PF _S is the filling rate of the system filled with only small particles.

According to Mcgeary, the filling rate in the irregular filling arrangement of single-sized spherical particles is about 60-65%, regardless of the particle size, when the particle diameter-to-particle diameter ratio exceeds 10 (James S. Reed, Principles of Ceramic). Processing 2nd Edition, pp219-222). Therefore, in the case of a system filled with large particles only, it can be assumed that PF _L is 0.6 ~ 0.65 in the above equation, and PF _S becomes 0 so that PF _L = PF _MAX is established. Because of this, it can be seen that the filling rate obtained in the irregular filling model of a single particle is 60 to 65%. In the same way, the fill factor PF _S of a system consisting of small particles can also be assumed to be 0.60-0.65. This results in a theoretical maximum fill factor PF _MAX of 85-88% for a system filled with two particles of different average particle diameters.

In this case, when the theoretical maximum filling rate (PF _MAX ) can be obtained, the volumes V _L and V _S of the large particles and the small particles are as follows.

V _L = 1-V _s ....... (Equation 2)

V _L = PF _L / PF _MAX ....... (Equation 3)

The maximum filling rate (PF _MAX ) of the second metal nanoparticles 120 having a relatively large second average particle diameter and the first metal nanoparticles 110 having a relatively small first average particle diameter is 0.86. The range of V _L for is obtained from Equations 1 and 3 above.

Substituting the V _L value and Equation 2 into the following volume ratio (V _L / V _s ),

V _L / V _s = 2.307 to 3.095 is obtained.

That is, the volume ratio (V _L / V _s ) of the relatively large second metal nanoparticles 120 contained in the conductive ink composition 130 and the relatively small first metal nanoparticles 110 is in the range of 2.307 to 3.095. The maximum fill factor (PF _MAX ) is obtained when at.

Another factor influencing the filling rate is the ratio of the second average particle size R _L of the second metal nanoparticle to the first average particle size R _S of the first metal nanoparticle. In order to improve the filling rate by mixing the metal particles, the first average particle size R _S of the first metal nanoparticles should be smaller than the size of the gap between the second metal nanoparticles. The ratio of the second average particle size R _L of the second metal nanoparticle of the present embodiment to the first average particle size R _S of the first metal nanoparticle is greater than two. That is, the second average particle diameter R _L of the second metal nanoparticles is at least twice the first average particle diameter R _S of the first metal nanoparticles. As such, when the ratio of the second average particle size R _L of the second metal nanoparticles to the first average particle size R _S of the first metal nanoparticles is 2 or more, there is a filling effect due to the mixing of the two particles. When the ratio of the second average particle size (R _L ) of the metal nanoparticles to the first average particle size (R _S ) of the first metal nanoparticles is greater than 7, the fine particles become very homogeneous to obtain a high filling rate.

Therefore, in order to improve the filling rate, the ratio of the second average particle size R _L of the second metal nanoparticles to the first average particle size R _S of the first metal nanoparticles is not less than 2, for example, 3 It is preferable to mix the 2 metal nanoparticles and the first metal nanoparticles at a volume ratio (V _L / V _s ) of 2.31 to 3.09.

The first and second metal nanoparticles 110 and 120 may be selected from the group consisting of copper, gold, silver, nickel, palladium, platinum, and aluminum, respectively.

The first and second metal nanoparticles 110 and 120 may be mixed in a composition having a process point in which they melt together. When the first and second metal nanoparticles 110 and 120 have a process point, the melting point of the electrode pattern formed of the conductive ink composition may be lowered, thereby forming the electrode pattern at a low temperature. For example, the second metal nanoparticles 120 may be copper (Cu), and the first metal nanoparticles 110 may be nickel (Ni) or silver (Ag).

The first and second metal nanoparticles 110 and 120 of the present embodiment may be mixed in a solvent. The term "solvent" in the present specification may be a single solvent or a mixed solvent in which two or more materials are mixed, and is also used to include additives such as a reducing agent and a dispersant.

In the present embodiment, it is preferable to mix 15 to 20% by weight of the first and second metal nanoparticles 110 and 120 and 80 to 85% by weight of the solvent. When the first and second metal nanoparticles 110 and 120 are less than 15 wt%, the conductivity of the electrode pattern formed by the conductive ink composition may be degraded. Rheological properties can be degraded.

The solvent of the present embodiment may include a first solvent and a second solvent so that the first and second metal nanoparticles 110 and 120 can be easily dispersed.

The first solvent is ethylene glycol, diethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, hexylene glycol, Glycerine may be any one or more selected from the group consisting of.

Second solvent is ethyl alcohol, methyl alcohol, acetone, isopropyl alcohol, isopropanol, toluene, hexane, heptane, methyl ethyl ketone Ethyl Ketone), ethyl lactate (Ethyl Lactate) may be any one or more selected from the group consisting of.

In order to more effectively disperse the first and second metal nanoparticles 110 and 120 in the solvent, the conductive ink composition of the present exemplary embodiment may include capping organic molecules adsorbed on the first and second metal nanoparticles 110 and 120. It may further include. Polyvinylpyrrolidone (PVP: PolyVinylPrrolidone) may be suitably exemplified as the dispersant, but the dispersant is not limited thereto.

It is preferable that the viscosity of the conductive ink composition of this embodiment is 0.5 to 40 mPa · s, satisfies Newtonian flow conditions, and has a surface tension of 20 to 70 mN / m.

Hereinafter, a method of manufacturing a conductive ink composition including the above-described dispersant, a first solvent, a second solvent, and the first and second metal nanoparticles 110 and 120 will be described.

First, the first and second metal nanoparticles 110 and 120 are provided. The first and second metal nanoparticles 110 and 120 may be manufactured in a manner known in the art. In this case, the average particle diameter ratio of the second metal nanoparticles 120 and the first metal nanoparticles 110 may be 2 or more, for example, 3.

Subsequently, the first and second solvents and dispersants and the first and second metal nanoparticles 110, 110, 120 to 120 wt% of the first and second metal nanoparticles 110 and 120 in the total conductive ink composition. 120). The first and second solvents and dispersants may use the materials as described above.

Subsequently, a mixture of these first and second solvents and dispersants and the first and second metal nanoparticles 110 and 120 is uniformly mixed to complete the conductive ink composition. For uniform mixing, for example, ball milling, planarity milling, and sonication can be used.

Specifically, the conductive ink composition was prepared according to the following preparation example, and the characteristics thereof were tested.

Preparation Example 1 Preparation of First Metal Nanoparticles

Silver having excellent conductivity (Ag) was selected as the first metal nanoparticles and manufactured to a size of 20 nm.

80 g of polyvinylpyrrolidone (PVP) as a dispersant was completely dissolved in 300 ml of ethylene glycol by mechanical stirring at room temperature. The mixture was then heated to 120 ° C. Meanwhile, 12.8 g of silver nitrate (AgNO 3) was added to ultrapure water (20 ml) and mechanically stirred to prepare a completely dissolved silver nitrate solution. The silver nitrate solution was injected into the solution heated to 120 ° C. and maintained in the syringe for 1 hour, followed by reaction. Through this, spherical monodisperse silver particles having an average diameter of 20 nm were prepared.

Preparation Example 2 Preparation of Second Metal Nanoparticles

As the second metal nanoparticles, copper (Cu) having excellent conductivity and low cost was selected and manufactured to a size of 60 nm.

16 g of polyvinylpyrrolidone (PVP) as a dispersant was mixed with 220 ml of diethylene glycol as a solvent, and completely dissolved by mechanical stirring at room temperature. In addition, 1.7578 g of sodium phosphinate monohydrate, a reducing agent, was added to the solvent and dispersant mixture and completely dissolved by mechanical stirring at room temperature. The mixture solution was heated to 140 ° C. with stirring. Meanwhile, 10.1672 g of kappa sulfate pentahydrate, which is a copper salt, was mixed with 30 g of ultrapure water and completely dissolved at room temperature by mechanical stirring to prepare a copper salt solution. The copper mixture solution was injected into the heated mixture solution at an injection rate of 2 ml per minute using a syringe pump. In this state, the solution was maintained for 1 hour to react, and after completion of the reaction, particles were separated by centrifugation. The separated particles were washed three times with methanol and dried in a vacuum oven. This produced spherical monodisperse copper nanoparticles having an average diameter of 60 nm in length.

Preparation Example 3 Preparation of Conductive Ink Composition

 Copper nanoparticles having excellent monodispersity and silver particles in a solvent containing ethylene glycol as a first solvent and methyl alcohol as a second solvent were mixed in a volume ratio of 2: 1, 3: 1, and 4: 1. Copper and silver nanoparticles were added to have a solid fraction of 20% by weight based on the total solution. As the dispersant, capping organic molecules adsorbed on the copper nanoparticles and silver particles were used. The solution was uniformly mixed using sonication and planar tree milling to prepare a conductive ink composition. In order to confirm the dispersibility of the first and second nano metal particles of the conductive ink composition, the viscosity characteristic according to the shear rate was measured and shown in FIG. 3.

Referring to FIG. 3, it can be seen that as the shear rate is increased, the viscosity characteristic of the conductive ink composition does not change and is almost constant. This means that the dispersion stability of the conductive ink composition solution is excellent.

Hereinafter, a method of forming an electrode pattern according to a second exemplary embodiment of the present invention will be described in detail with reference to FIGS. 4 to 6. 4 is a flowchart illustrating a method of forming an electrode pattern according to a second exemplary embodiment of the present invention. 5 and 6 are cross-sectional views showing an electrode pattern forming method according to a second embodiment of the present invention. In this embodiment, the electrode pattern is formed using the conductive ink composition of the previous embodiment, and thus descriptions overlapping with the previous embodiment will be omitted or simplified.

4 to 6, the first and second metal nanoparticles are provided (S ₁₀₀ ). The first and second metal nanoparticles are provided in the same manner as in the first embodiment of the present invention.

Subsequently, a conductive ink composition is provided (S ₂₀₀ ). The second and first metal nanoparticles are mixed and milled in the first and second solvents at a volume ratio of 2.31 to 3.09. A conductive ink composition is also provided in the same manner as in the first embodiment of the present invention.

4 and 5, the shape 130 of the electrode pattern is formed on the substrate 10 (S ₃₀₀ ). The shape 130 of the electrode pattern is formed using a conductive ink composition including the first and second metal nanoparticles 110 and 120. The conductive ink composition is applied onto the substrate 10 to form the shape 130 of the electrode pattern by any one method selected from the group consisting of droplet casting, inkjet printing, and screen printing.

Herein, the substrate 10 may be a flexible substrate such as a soft and light plastic.

Subsequently, referring to FIGS. 4 to 6, the substrate 10 is subjected to low temperature heat treatment to form an electrode pattern 140 (S ₄₀₀ ). The electrode pattern 140 may be an electrode pattern of various electronic devices. For example, the electrode pattern 140 may be a gate electrode pattern, a data electrode pattern, or the like in the liquid crystal display.

Low temperature heat treatment temperature may be 100 ~ 300 ℃. This temperature is required to be a temperature such that the flexible substrate 10 is not damaged by heat treatment. Therefore, it is necessary to use a conductive ink composition that exhibits good conductivity at a temperature at which the thermal stability of the flexible avoidance film 10 is secured.

In order to suppress the formation of the oxide film on the electrode pattern 140 during the heat treatment, the heat treatment may be performed in a vacuum atmosphere, a reducing atmosphere using hydrogen gas, and an inert atmosphere using nitrogen, argon, and helium gas. The vacuum treatment may be carried out in a vacuum atmosphere of 10 ⁻³ torr or less.

Since the first and second metal nanoparticles 110 and 120 are provided in the nanometer size and the melting point is reduced, the electrode pattern 140 is formed by fusion with each other even by the low temperature heat treatment as described above. The conductivity of the electrode pattern 140 is increased by fusion of the first and second metal nanoparticles 110 and 120.

In addition, since the electrode pattern shape 130 is formed using the conductive ink composition in which the second and first metal nanoparticles 120 and 110 are present in a volume ratio of 2.31 to 3.09, the electrode pattern 140 is formed of dense metal particles. It is made of wood and has excellent conductivity.

7A to 12, the characteristics of the electrode pattern formed by the method according to the present embodiment will be confirmed. 7A to 7C are cross-sectional views comparing an electrode pattern formed by an electrode pattern forming method according to a second exemplary embodiment of the present invention with an electrode pattern according to a comparative example. 8A to 8C are photographs comparing an electrode pattern formed by an electrode pattern forming method according to a second exemplary embodiment of the present invention with an electrode pattern according to a comparative example. 9A to 10D are photographs comparing an electrode pattern formed by changing a heat treatment temperature according to an electrode pattern forming method according to a second exemplary embodiment of the present invention with an electrode pattern according to a comparative example. 11 and 12 are photographs comparing the electrode pattern formed by varying the heat treatment temperature according to the electrode pattern forming method according to the second embodiment of the present invention with the electrode pattern according to the comparative example.

7A to 7C, an electrode formed by heat treatment at 300 ° C. using a conductive ink composition including silver (Ag) as first metal nanoparticles and copper (Cu) as second metal nanoparticles, respectively. The cross section of the pattern 140 may be confirmed. This figure is a photograph taken by forming a cross section on the electrode pattern 140 by a focused ion beam (FIB). When the volume ratio of copper and silver particles is 3: 1 as shown in FIG. 7A, the electrode pattern 140 was the most dense, and when the volume ratio of copper and silver particles is 2: 1 and 4: 1 as shown in FIGS. 7B and 7C. In the electrode pattern 140, the gap between the particles is visually recognized and the particles are not densely arranged. Here, when the volume ratio of copper and silver particles is 3: 1, it may be inferred that the conductivity of the electrode pattern 140 is the highest.

8A to 8C, when the volume ratio of copper and silver particles is 3: 1 as shown in FIG. 8A, the area of the voids shown in black is the smallest, and the volume ratio of copper and silver particles as shown in FIGS. 8B and 8C. Is 2: 1 and 4: 1, the area of the voids with respect to the area of the entire quadrangle was wider than in the case of FIG. 8A. When the copper particles have a volume ratio of 2: 1, 3: 1, and 4: 1, the porosity is 16%, 14%, and 24%, respectively, and the volume ratio of copper particles and silver particles in the conductive ink composition is 3: 1. In the case of, the packing density of the metal particles was the highest. The highest filling rate of 86% was obtained when copper and silver particles were mixed in a volume ratio of 3: 1, which is similar to the theoretical value according to the Furnas rule.

9A to 10D, the electrode pattern including both copper and silver may be confirmed that fusion occurs well even at low temperatures. 9A to 9D are scanning electron microscope (SEM) photographs of electrode patterns formed by heat treatment of electrode pattern shapes formed using a conductive ink composition containing only copper at 175 ° C, 225 ° C, 275 ° C and 325 ° C, respectively. It is shown. In this case, it can be confirmed that fusion between copper particles hardly occurred at 175 ° C and 225 ° C at low temperatures.

10A to 10D illustrate an electrode pattern formed by heat-treating an electrode pattern shape formed by using a conductive ink composition containing copper and silver in a volume ratio of 3: 1 at 175 ° C, 225 ° C, 275 ° C, and 325 ° C, respectively. The scanning electron microscope (SEM) photograph of the is shown. In this case, it can be confirmed that good fusion occurred between the copper particles and the silver particles at high temperatures as well as at low temperatures of 175 ° C and 225 ° C.

Referring to FIG. 11, it can be seen that an electrode pattern formed by using a conductive ink composition containing only copper has a rapid increase in specific resistance at low temperature. On the contrary, it can be seen that the electrode pattern shape formed using the conductive ink composition containing copper and silver in a volume ratio of 3: 1 maintains a good resistivity even at low temperatures.

Referring to FIG. 12, the resistivity of an electrode pattern formed by using a conductive ink composition including copper and silver in a volume ratio of 3: 1, 2: 1, and 4: 1, respectively, was compared. The electrode pattern formed by using a conductive ink composition containing copper and silver in a volume ratio of 2: 1 and 4: 1 has a sharp increase in resistivity at low temperature, but a conductive ink containing copper and silver in a volume ratio of 3: 1. The electrode pattern formed using the composition showed a slight increase in resistivity at low temperatures.

According to the electrode pattern forming method according to the present embodiment, by forming the electrode pattern using the conductive ink composition, expensive equipment such as photolithography equipment is not required, thereby reducing the electrode pattern forming cost and fearing environmental pollution due to an etching process. Can be prevented. In addition, since the electrode pattern can be formed at a low temperature, the electrode pattern can be formed without damaging the flexible substrate. In addition, by forming a conductive ink composition using nanoparticles having different sizes of 2.31 to 3.09, an electrode pattern having excellent electrical conductivity can be obtained.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

1A to 1C are schematic diagrams showing the first and second metal particle sizes in the conductive ink composition according to the first embodiment of the present invention and the metal particle sizes of the conductive inks of the comparative example.

2 is a graph showing the packing bulk density of the conductive ink composition according to the first embodiment of the present invention in comparison with a comparative example.

3 is a graph showing the viscosity of the conductive ink composition according to the first embodiment of the present invention.

4 is a flowchart illustrating a method of forming an electrode pattern according to a second exemplary embodiment of the present invention.

5 and 6 are cross-sectional views showing an electrode pattern forming method according to a second embodiment of the present invention.

7A to 7C are cross-sectional views comparing an electrode pattern formed by an electrode pattern forming method according to a second exemplary embodiment of the present invention with an electrode pattern according to a comparative example.

8A to 8C are photographs comparing an electrode pattern formed by an electrode pattern forming method according to a second exemplary embodiment of the present invention with an electrode pattern according to a comparative example.

9A to 10D are photographs comparing an electrode pattern formed by changing a heat treatment temperature according to an electrode pattern forming method according to a second embodiment of the present invention with an electrode pattern according to a comparative example.

11 and 12 are photographs comparing the electrode pattern formed by varying the heat treatment temperature according to the electrode pattern forming method according to the second embodiment of the present invention with the electrode pattern according to the comparative example.

 (Explanation of symbols for the main parts of the drawing)

10: substrate 110: first metal nanoparticles

120: second metal nanoparticle 130: conductive ink composition

140: electrode pattern

Claims (11)

Providing a substrate; A first metal nanoparticle having a first average particle diameter, a second metal nanoparticle having a second average particle diameter that is at least two times the first average particle diameter, and a solvent, wherein the second metal nanoparticle mixed with the solvent and the Forming a shape of an electrode pattern on the substrate using a conductive ink composition having a volume ratio of first metal nanoparticles of 2.31 to 3.09; And Electrode pattern forming method comprising the step of heat-treating the shape of the electrode pattern to a low temperature of less than 300 ℃. The method of claim 1, Forming the shape of the electrode pattern, Providing each of the first metal nanoparticle and the second metal nanoparticle; Mixing the second and first metal nanoparticles with a solvent in a volume ratio of 2.31 to 3.09 and milling to provide an ink composition; And And forming the shape of the electrode pattern by applying the ink composition to the substrate in any one manner selected from the group consisting of droplet casting, inkjet printing, and screen printing. The method of claim 1, The heat treatment is an electrode pattern forming method performed at a temperature of 100 ~ 300 ℃. The method of claim 1, And the substrate is a flexible substrate. A first metal nanoparticle having a first average particle diameter, a second metal nanoparticle having a second average particle diameter that is at least two times the first average particle diameter, and a solvent, The volume ratio of the second metal nanoparticles and the first metal nanoparticles mixed in the solvent is 2.31 to 3.09. The method of claim 5, The gap between the second metal nanoparticles is larger than the first average particle diameter of the first metal nanoparticles conductive ink composition. The method of claim 6, The second average particle diameter is at least seven times the first average particle diameter of the conductive ink composition. The method of claim 5, The first and second metal nanoparticles have a process point conductive ink composition. The method of claim 8, The first and second metal nanoparticles are each selected from the group consisting of copper, gold, silver, nickel, palladium, platinum and aluminum. The method of claim 5, The solvent is at least one first solvent selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, glycerin, and ethyl alcohol, methyl alcohol, acetone, isopropyl alcohol And at least one second solvent selected from the group consisting of toluene, hexane, heptane, methyl ethyl ketone, ethyl lactate. The method of claim 5, A conductive ink composition comprising 15 to 20% by weight of the first and second metal nanoparticles and 80 to 85% by weight of the solvent.

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