KR20160088173A - Ink or Paste Compositions with High Conductivity for Forming Micropatterns - Google Patents

Abstract

The present invention relates to an ink or paste composition for forming fine patterns and a highly conductive fine pattern electrode using the same. The ink / paste composition of the present invention comprises carbon-coated metal nanoparticles suitable for cold-sintering and does not require a dispersion stabilizer. In addition, the ink / paste composition of the present invention can stably form a fine pattern in the range of 50-300 μm through a double low-temperature sintering process (oxidation and reduction process). Accordingly, the ink / paste composition of the present invention not only can form highly conductive metal micropatterns on a substrate, more specifically a flexible substrate, but also exhibits much better electrical properties than conventionally used polymeric materials, Can be usefully applied.

Description

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a high conductive ink or paste composition for forming fine patterns,

The present invention relates to a high conductivity ink or paste composition for forming fine patterns through low temperature-sintering.

BACKGROUND ART [0002] Recently, electronic devices, information terminal devices, and the like have become smaller and lighter, and electronic components used in devices are becoming smaller and smaller. As a result, the size of the wiring pattern for mounting in the electronic component gradually becomes smaller, and the width of the wiring pattern and the face of the wiring become narrow. In the field of printed electronics, many researches have been made to realize fine patterns in flexible devices. In order to realize such a fine pattern, the rheological characteristic of the conductive paste is very important.

On the other hand, the conductive paste for screen printing has not only a high viscosity characteristic but also an ideal viscoelastic characteristic (a high elastic property (gel) in the absence of external force and a high viscosity property (sol) It is necessary to have a high restoration characteristic. If it is satisfied, it is possible to realize a high aspect ratio fine pattern without spreading after pattern formation. Therefore, it is very important to manufacture the conductive paste according to the rheological characteristics in order to realize a fine pattern while satisfying a certain level of electrode pattern. So far, many researches on the production of conductive pastes have been published. However, research on conductive paste including copper nanoparticles coated with a carbon layer has not been reported so far. In order to realize a fine line width, it is necessary to observe the change of the paste rheological property according to the amount of the epoxy binder and the kind of the solvent, The results are insignificant, and there is a continuing trend in the industry.

Numerous papers and patent documents are referenced and cited throughout this specification. The disclosures of the cited papers and patent documents are incorporated herein by reference in their entirety to better understand the state of the art to which the present invention pertains and the content of the present invention.

The present inventors have sought to develop an ink / paste composition comprising a metal film of high conductivity and metal nanoparticles for pattern formation. As a result, we have developed an ink / paste composition comprising carbon coated metal nanoparticles (e.g., copper nanoparticles), a solvent and a binder, wherein the composition does not need to include a dispersion stabilizer, Sintering at a low temperature (e.g., 200 캜 or 250 캜) for a period of time (for example, 5 to 10 minutes) and then sintering at a reduced temperature for a short period of time (for example, 5 minutes to 10 minutes) 300 [mu] m, and thus the present invention has been completed.

Accordingly, an object of the present invention is to provide an ink or paste composition for forming a fine pattern.

Another object of the present invention is to provide a highly conductive fine pattern electrode.

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention, claims and drawings.

According to one aspect of the present invention, the present invention provides a carbon nanotube composition comprising 60-70 wt% (wt%) carbon-coated metal nanoparticles; 25-35 wt% solvent; And 3-7% by weight of a binder.

According to another aspect of the invention, the present invention provides a highly conductive fine patterned electrode comprising the above ink or paste composition.

The present inventors have sought to develop an ink / paste composition comprising a metal film of high conductivity and metal nanoparticles for pattern formation. As a result, we have developed an ink / paste composition comprising carbon coated metal nanoparticles (e.g., copper nanoparticles), a solvent and a binder, wherein the composition does not need to include a dispersion stabilizer, Sintering at a low temperature (e.g., 200 캜 or 250 캜) for a period of time (for example, 5 to 10 minutes) and then sintering at a reduced temperature for a short period of time (for example, 5 minutes to 10 minutes) It was confirmed that fine patterns in the range of 300 μm could be stably formed.

The carbon-coated metal nanoparticles that can be used in the present invention can be any metal that can be necked together at a low temperature, specifically 300 ° C or less, more specifically 180-280 ° C, and more particularly 200-250 ° C. It is also possible.

In some embodiments of the present invention, the carbon-coated metal nanoparticles are prepared by electrical explosion and have a size of 10-200 nm, more specifically 10-100 nm, and more specifically 10-40 nm nm.

 In some embodiments of the invention, the metal nanoparticles in the composition of the present invention comprise 50-90 wt.%, More specifically 55-80 wt.%, More specifically 60-70 wt.% And most specifically 65 wt. % (Note: Figures 2 to 4).

In some embodiments of the present invention, the metal includes but is not limited to Cu, Ni, Fe, Al, Zn, Co, Au, Ag, Pt and combinations thereof, most particularly Cu. More specifically, the surroundings of copper nano-particles are rapidly oxidized under process (e. G., Oxygen and hydrogen _{atmosphere) (Cu -> CuO 0 .67} ) and the slow oxidation-while experiencing a (CuO _{0 .67>} CuO) copper nano To form copper oxide on the surface of the particles, which is very harmful in terms of conductive printing application. More specifically, the presence of the copper oxide is not easy to industrially apply because of an increase in sintering temperature and a decrease in electrical conductivity. In order to solve the above problems, various coating methods have been tried on the surface of copper nanoparticles: a) carbon-based materials (carbon and graphene); (b) a surfactant and a polymer; (c) silica; (d) metal (Magdassi, S. et al . , Materials 3: 4626-4638 (2010)). Above all, the method of using carbon-based materials (carbon and graphene) is difficult to achieve high conductivity when the carbon layer is left after sintering, and when the carbon layer is removed in an oxidizing atmosphere, Process. In particular, as the crystallinity of the carbon layer increases, the sintering temperature must also increase. In order to solve the difficulty of high-temperature sintering according to the carbon coating, the present inventors have confirmed that it is possible to manufacture a high-conductivity metal film / pattern or electrode through low-temperature sintering. In addition, when a fine pattern is formed using the composition of the present invention, a carbon coating layer formed from carbon-coated metal nanoparticles is very important (refer to FIGS. 5 to 7, and further results are not shown). In some embodiments of the present invention, the carbon coated metal nanoparticles that may be used in the present invention are metal nanoparticles coated with an amorphous carbon layer.

The solvent used in the ink / paste composition of the present invention is not particularly limited as long as it is a solvent suitable for the double low temperature-sintering condition of the present invention (for example, a solvent having a high viscosity at a temperature of 180 ° C or higher) For example, alcohols, glycols, alkyls, and the like. More specifically, the solvent may be selected from the group consisting of alpha-terpineol, ethyl alcohol, methyl alcohol, isopropyl alcohol, 2-methoxy alcohols such as methanol, ethanol, propyl alcohol, pentyl alcohol, hexyl alcohol, butyl alcohol and octyl alcohol; (Ethylene glycol), diethylene glycol, triethylene glycol, polyethylene glycol, ethylene glycol monomethyl ether (EGME), diethylene glycol monoether (DGME), propylene glycol glycols such as propylene glycol, dipropylene glycol, hexylene glycol, triethylene glycol monomethyl ether (TGME), and propylene glycol methyl ether acetate Ryu; But are not limited to, methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, Undecane, dodecane and the like; Organic solvents such as toluene, xylene, dimethyl carbonate, diethyl carbonate and ethyl lactate; Glycerine; Acetone; Formamide; Methyl ethyl ketone; And cyclohexanone, but are not limited thereto.

In some embodiments of the present invention, the solvent used in the present invention may be a glycol or an alcohol.

 In some embodiments of the invention, the metal nanoparticles in the composition of the present invention comprise 10-50 wt-%, more specifically 15-45 wt-%, more specifically 20-40 wt-% and most specifically 25- 35% by weight.

The composition of the present invention can be used very easily and effectively for the production of highly conductive electrode patterns / films via double low-temperature sintering (oxidation and reduction steps) for a very short period of time.

More specifically, an ink / paste composition is first prepared by mixing carbon-coated metal nanoparticles with a solvent. In addition, the ink / paste composition of the present invention may further include a binder to improve adhesion with the substrate. The binder generally used may include an organic binder such as an epoxy resin, a phenol resin (phenol + formaldehyde) polyurethane resin, a polyamide resin, an acrylic resin, a urea / melamine resin, and a silicone resin. The content of the binder may generally range from 1 to 10% by weight (wt%) based on the total paste composition, but is not limited thereto.

In some embodiments of the present invention, the binder content in the compositions of the present invention comprises 1-10% by weight, more specifically 2-8% by weight, and more particularly 3-7% by weight 2 to Fig. 4).

In addition, the ink or paste composition of the present invention does not require a dispersion stabilizer for maintaining the dispersion of nanoparticles, and may additionally contain other components (for example, additives) for proper viscosity.

Additives that may be used in the present invention include, but are not limited to, thixotropic agents and leveling agents for improving the ink / paste application properties and the formation properties of the highly conductive electrodes. The thixotropic agent is used to rapidly decrease the viscosity of the composition at the beginning of printing to increase the mesh surface throughput efficiency and to increase the viscosity of the composition at the late stage of printing to suppress the spread-out of the pattern And the leveling agent is used to control the flowability of the composition and may be added when a dispersion stabilizer is used.

In some embodiments of the present invention, the viscosity of the ink or paste composition of the present invention is from about 40,000 to 150,000 centipoise (centipoise).

Thereafter, the conductive film / pattern is applied onto the substrate using the ink / paste composition prepared above. The substrate may be a substrate well known in the art if the film formed by applying the composition is closely adhered. For example, a material made of metal, ceramics, glass, polymer, or the like can be used. More specifically, an inorganic material excellent in heat resistance such as a copper plate, a copper foil and a glass, or a plastic film having a relatively low heat resistance temperature such as PEN or polycarbonate can be used, but the present invention is not limited thereto. The substrate may be a flexible substrate such as ceramic, glass, silicon, or the like. Examples of the flexible substrate include paper, polymer film and the like, and more specifically, polyimide (PI), polybutylene terephthalate (PBT), polyether naphthalate (PEN), polyether sulfone (PES) (Nylon), polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), polycarbonate (PC), polyarylate (PAR), polyarylate, heat resistant epoxy And the like.

In some embodiments of the present invention, the substrate of the present invention is a flexible substrate.

In some embodiments of the present invention, the substrate material of the present invention can be selected from the group consisting of polyimide, polyetherimide, polybutylene terephthalate, polysulfone, polyether, heat resistant epoxy, glass, silicone, polyarylate, Ceramics and FR-4, and more specifically polyimide. The term " polyimide " In addition, the flexible substrate on which the ink / paste composition of the present invention is used may be an FPC, COB, COF, RFID, LED, OLED, OTFT, NFC antenna, NFC-Tag, touch screen, ), A passport (E-passport), a thin film battery, a thin film memory, and the like.

The method of applying the ink / paste composition of the present invention may be a method known in the art such as screen printing, spin coating, spreading, and dipping. For example, screen printing, Printing, gravure printing, inkjet printing, offset printing, pad printing, flexography printing, stencil printing, spin coating, roll coating, dip coating, deep coating, spray coating, dip coating, flow coating, doctor blade, dispensing, imprinting, xerography, And lithography. However, the present invention is not limited thereto.

In some embodiments of the present invention, application of the ink / paste composition of the present invention is carried out by screen printing.

Next, the substrate coated with the ink / paste composition containing the carbon-coated copper nanoparticles (specifically, the flexible substrate) is naturally dried, and then the film is heated in an oxidizing atmosphere for a short time at a temperature of 200 ° C or more and 250 ° C or less Lt; / RTI > In the present invention, it is possible to further include a step of cleaning the surface of the substrate before performing the low-temperature-sintering.

In some embodiments of the present invention, the ink / paste composition has a storage elastic modulus higher than a loss elastic modulus at a shear stress section lower than 50 Pa, a loss modulus higher than a storage elastic modulus at a shear stress section at 50-1000 Pa, The storage elastic modulus is higher than the loss elastic modulus in the shear stress range lower than 100 Pa, the loss elastic modulus in the shear stress range in the range of 100-1000 Pa is higher than the storage modulus, and more specifically, in the shear stress range lower than 200 Pa, The loss elastic modulus is higher than the storage elastic modulus, and the shear stress range of 200-1000 Pa is higher than the storage elastic modulus.

The term " sintering " as used herein refers to any process of forming a target from a metal powder by heating the powder (e.g., metal nanoparticle powder) to a temperature below the melting point.

In some embodiments of the present invention, the sintering of the step is carried out for 5 to 30 minutes, more particularly 5 to 20 minutes, more particularly 5 to 10 minutes and most particularly 5 minutes Conduct.

In some embodiments of the present invention, the oxidizing atmosphere in the step is a gas atmosphere / state containing oxygen, more specifically air or a mixed gas containing oxygen (e.g., nitrogen (N ₂ ) And argon (Ar)), and more particularly air.

Since the oxidation process causes a significant increase in electrical resistance due to the surface oxide film formed by the metal oxide, the surface oxide film must be essentially reduced to provide a suitable highly conductive substrate / electrode. Thus, the sintered film or pattern is finally sintered at a temperature of 200 ° C or higher and 250 ° C or lower for a short period of time in a reducing atmosphere.

In some embodiments of the present invention, the reducing atmosphere in the step may be a gas atmosphere / condition comprising hydrogen (H ₂ ), more specifically a mixed gas comprising hydrogen, and more particularly argon Ar) / 10% hydrogen mixed gas.

Interestingly, as the first low temperature-sintering process (oxidation process) increases, the second low-temperature sintering process (reduction process) of the present invention requires the same or longer time (no results are shown). For example, if the first low-temperature-sintering process is 30 minutes, the second low-temperature sintering process may take more than 30 minutes, more specifically, 30 minutes or more, in order for the metal film or pattern to have a suitable electrical resistance value Minute to 60 minutes. In the reduction process, the metal oxide layer formed through the first low temperature-sintering process is reduced to leave only the necked metal nanoparticles.

In some embodiments of the present invention, the sintering of the step is carried out for 5 minutes to 60 minutes, more particularly 5 minutes to 40 minutes, more particularly 5 minutes to 20 minutes, and most particularly 5 minutes Conduct.

As a result, the double low temperature-sintering process of the present invention can form a highly conductive electrode pattern / film on a substrate while maintaining a low electrical resistance.

In some embodiments of the present invention, the pattern is micropatterns and the fine pattern is in the range of 50-800 μm, more specifically in the range of 50-500 μm, and more particularly in the range of 50-300 μm .

In some embodiments of the present invention, the electrode pattern / membrane of the present invention has an electrical resistance value (Ω · cm) of 2.60 × 10 ^-5 or less.

The features and advantages of the present invention are summarized as follows:

(a) The present invention relates to an ink or paste composition for forming fine patterns and a highly conductive fine pattern electrode using the same.

(b) The ink / paste composition of the present invention comprises carbon-coated metal nanoparticles suitable for low temperature-sintering, and does not require a dispersion stabilizer.

(c) In addition, the ink / paste composition of the present invention can stably form a fine pattern in the range of 50-300 μm through a double low-temperature sintering process (oxidation and reduction process).

(d) Therefore, the ink / paste composition of the present invention not only can form a highly conductive metal pattern on a substrate, more specifically a flexible substrate, but also exhibits much better electrical properties than conventionally used polymeric materials And can be industrially useful.

FIG. 1 shows the particle size and distribution of the copper nanoparticles of the present invention.
FIG. 2A is a graph showing a change in viscosity versus shear rate with addition of an epoxy binder to the nano ink / paste of the present invention, and FIG. 2B is a graph showing viscosity change versus shear rate according to the type of solvent in the nano ink / paste of the present invention.
FIG. 3A is a graph showing the change in viscoelasticity according to the addition of an epoxy binder to the nanoink / paste of the present invention, and FIG. 3B is a graph showing changes in viscoelasticity according to the type of solvent in the nanoink / paste of the present invention.
FIG. 4A shows the result of creep-recovery measurement according to the epoxy binder addition, and FIG. 4B shows the creep-recovery measurement result according to the solvent type.
5A is an optical image showing the shape of an electrode pattern sintered after printing by using a mask pattern having various linewidths using a nano-ink manufactured according to the amount of a binder, FIG. 5B is an optical image showing the line width of the electrode pattern printed according to the mask line width FIG. 5C is a 3D-surface profiler (height, 6.33 μm; and FIG. 5C) showing the width and height of a fine pattern (mask line width 50 μm) printed using a nano ink with 5 wt% Width, 49.92 [mu] m).
6A is an optical image showing the shape of a sintered electrode pattern after printing with a mask pattern having various linewidths using a nano-ink prepared by using a solvent DGME after fixing a binder amount (5 wt%), FIG. 6C is a 3D-surface profiler showing the width and height of the printed electrode pattern using a 50 μm line mask (height, 7.14 μm; and FIG. Width, 52.15 [mu] m).
7A is an optical image showing the shape of a sintered electrode pattern printed with a mask pattern of 50 μm using a nano-ink manufactured according to the amount of a binder, FIG. 7B shows an optical image after fixing a binder amount (5 wt% Is an optical image showing the shape of a sintered electrode pattern after printing with a mask pattern of 50 μm using nano ink manufactured according to the kind.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for describing the present invention in more detail and that the scope of the present invention is not limited by these embodiments in accordance with the gist of the present invention .

Example

Experimental Method

Carbon coated copper nanoparticles prepared by electric arc explosion method were used. First, an epoxy binder (Bisphenol A-type) having various concentrations (0-10 wt%; nano ink / paste weight) was added to an ethylene glycol (EG) solvent to prepare a vehicle and then mixed using a stirrer . The nano powder prepared in the vehicle solution was added at 65 wt% (based on nano ink / paste weight), respectively, to prepare nano ink / paste. The prepared nano ink / pastes were mixed by a propeller type mixer and then mixed three times using a 3-roll mill (INOUE S-43/411, Japan). In the mixing process, a defoaming agent can be selectively used, and in particular, a dispersion stabilizer is not required (securing the dispersibility by van der Waals force reduction in the solvent by the carbon layer). (7 phr) of dicyandiamide (Sigma-aldrich, USA) was added to the prepared nano ink / paste and re-mixed using a mixer to obtain a final ink / paste (# 1- # 5) were completed (Table 1). When a curing accelerator which is not a latent curing agent, a curing agent for room temperature curing or a low temperature curing is used, the curing at a low temperature causes rapid curing to prevent combustion of the carbon coating layer (specifically, the amorphous carbon coating layer) There was a problem in long-term storage.

The concentration of the epoxy binder (5 wt%) and the prepared nanoparticles (65 wt%) were fixed to observe the characteristics according to the solvent, and then ethylene glycol monoether (EGME), diethylene glycol monoether (DGME) The final nano ink / paste (# 6- # 8) was prepared by the same mixing procedure using alpha-terpineol solution (Table 1).

Sample Solvent (wt%) Filler (wt%) Binder (wt%) Curing agent (phr) #One EG (35) Cu @ C (65) - - #2 EG (34) Cu @ C (65) Epoxy (1) Dicyandiamide (7) # 3 EG (32) Cu @ C (65) Epoxy (3) Dicyandiamide (7) #4 EG (30) Cu @ C (65) The epoxy (5) Dicyandiamide (7) # 5 EG (25) Cu @ C (65) The epoxy (10) Dicyandiamide (7) # 6 EGME (30) Cu @ C (65) The epoxy (5) Dicyandiamide (7) # 7 DEME (30) Cu @ C (65) The epoxy (5) Dicyandiamide (7) #8 alpha -terpineol (30) Cu @ C (65) The epoxy (5) Dicyandiamide (7)

Composition of conductive ink / paste.

The dispersion characteristics of the nano ink / paste thus obtained were analyzed by a particle size analyzer (APS) using a sound wave. The rheological behaviors of nano ink / pastes according to initial viscosity and shear rate (0-100 s ^-1 ) were investigated using a viscometer. In addition, the micro-rheological characteristics (0-1000 Pa, 1 Hz) according to shear stress were measured using a viscoelasticity measuring device, and a creep-recovery measurement device (120 seconds creep (1 Pa) Removal after application, 120 seconds resilience measurement). After the detailed patterning, the anti-slump of the nano ink / paste was grasped.

The prepared nano ink / pastes were screen printed to form a conductive film on the flexible substrate to grasp the electrode patterns and adhesion characteristics, and the formed electrode patterns and films were oxidized in air at one stage in air at 200 DEG C and in a two- / 10% H ₂ ) for 5 minutes, respectively. The sintered electrode pattern is obtained by measuring the surface resistance through a 4-point probe and then multiplying the thickness by the resistivity value. In addition, the formed electrode pattern / film was examined for adhesion strength to the substrate through the adhesive strength measurement method of ASTM D3359.

Experiment result

First, the present inventors investigated the dispersion characteristics of the prepared nano ink / paste (Fig. 1). As a result of using the particle size analyzer, it was found that the nano ink / paste thus prepared had a particle size distribution (average particle size: about 26 nm) of 10-40 nm in the solvent and dispersion stability without dispersion of large particles (no dispersion stabilizer needed) , Which is inferred to be due to the effect of the steric hindrance by reducing the van der Waals force between the nanoparticles of the carbon layer at the copper interface.

The present inventors measured the viscosity of the nano ink / paste by the change of the shear rate with the addition of the epoxy binder. As can be seen from FIG. 2A, the nano ink / paste thus prepared is suitable for screen printing with an initial viscosity of about 40,000 to 150,000 cps (CentiPoise). In addition, the shear thinning behaviors showed a decrease in viscosity with increasing shear rate as a whole, and showed suitable behavior for screen printing.

On the other hand, in the case of sample No. 1 in which no binder is added, it shows a rapid viscosity decrease at low shear rate, which means that the network of particles in the solvent is very weakly formed. In contrast, as the amount of binder added increased, a strong network was formed due to the increase in intermolecular attraction between the binder and the particles, and the viscosity was maintained at a constant shear rate without changing the viscosity. As a result, the thixotropic index was improved as the amount of binder added increased. For reference, the initial viscosity increase due to the increase of the binder amount is due to the influence of the binder which is relatively higher in viscosity than the solvent.

The viscosity change of the shear rate according to the solvent used in the present invention was examined. In the case of nano ink / paste using other solvents (EGME, DGME, α-terpineol), the initial viscosity was suitable for screen printing between 34,500-78,000 cps. The viscosity according to the increase in shear rate Shear fluidization behavior.

Sample menstruum( wt %) bookbinder( wt %) T.I (5/50) ^* T.I (5/100) ^* #One EG (35) - 1.82 2.19 #2 EG (34) Epoxy (1) 6.40 9.61 # 3 EG (32) Epoxy (3) 8.84 18.82 #4 EG (30) The epoxy (5) 9.92 18.6 # 5 EG (25) The epoxy (10) 8.64 16.65 # 6 EGME (30) The epoxy (5) 6.52 9.49 # 7 DEME (30) The epoxy (5) 5.81 8.73 #8 alpha -terpineol (30) The epoxy (5) 7.71 17.72

Rheological Properties by Addition of Solvent and Binder.

^* Thixotropic index (TI); TI (5/50) = 5 rpm / 50 rpm; TI (5/100) = 5 rpm / 100 rpm.

In viscoelastic changes important in screen printing, the change in viscoelasticity due to shear stress due to binder addition was investigated (Fig. 3a). More specifically, the loss modulus is higher than the storage modulus in all the shear stress ranges tested in the No. 2 sample in which the binder-free sample 1 and the 1 wt% binder are added. Which means that the problem of spreading of the pattern after printing is generated, while it is advantageous in discharging and leveling characteristics at the time of screen printing. On the other hand, in case of sample No. 3 in which 3 wt% of binder is added and sample No. 4 in which 5 wt% of binder is added, the storage elastic modulus is higher than the loss elastic modulus in a low shear stress period, And exhibited higher ideal viscoelastic properties. However, in the case of the fourth sample, the overall storage elasticity is high and the leveling property is expected to be poor. On the other hand, in the case of the 5th sample in which the 10 wt% binder was added, the storage elasticity was higher than that in the whole area, which is advantageous for the fine line width, but the leveling and discharging problems are expected to result in poor printability .

It was also investigated how the use of other solvents causes any change in viscoelasticity (Fig. 3b). Viscoelastic trends were similar throughout the use of other solvents. More specifically, the low shear stress section exhibited an ideal paste viscoelastic characteristic in which the storage elastic modulus was higher than the loss elastic modulus and the high shear stress section had a loss elastic modulus higher than the storage modulus. On the other hand, in addition to ethylene glycol monoether (EGME) and diethylene glycol monoether (DGME) having lower viscosity and molecular weight than ethylene glycol, sample No. 8 containing alpha-terpineol having higher viscosity and molecular weight than ethylene glycol , The leveling property was improved by showing lower elasticity property as compared with the viscoelasticity of sample No. 4 contained in ethylene glycol.

In general, elasticity is affected by the viscosity, molecular weight and molecular size of the solvent. However, terpineol is higher and larger than ethylene glycol in all parameters, so it should have higher elasticity and higher properties, but this was unexpected result. On the other hand, ethyleneglycol has a small number of non-polar groups in the molecular structure and -OH groups on both sides, and in the case of terpineol, many non-polar groups and one -OH group . Here, the intensity of the intermolecular attraction is governed by the London dispersion force in the case of the non-polar group, and the -OH group by the force by the hydrogen bond. On the other hand, in the case of ethylene glycol, it is considered that viscoelastic properties, especially elastic properties, are formed much higher than terpineol because of strong binding force with particles or binders by -OH groups on both sides.

On the other hand, a creep-recovery test was performed on each sample to evaluate the formation of fine patterns (Figs. 4A-4B and Table 3).

Sample menstruum( wt %) bookbinder( wt %) J ₃ (One/ Pa ) J _OR (One/ Pa ) R (%) ^* #One EG (35) - 2.70X10 ^- 2.01X10 ^- 7.42 #2 EG (34) Epoxy (1) 3.82X10 ^-3 1.21X10 ^-3 30.7 # 3 EG (32) Epoxy (3) 1.08X10 ^-3 7.96X10 ^-4 73.9 #4 EG (30) The epoxy (5) 4.22X10 ^-4 3.36X10 ^-4 79.5 # 5 EG (25) The epoxy (10) 2.10X10 ^-4 1.74X10 ^-4 83.3 # 6 EGME (30) The epoxy (5) 8.95X10 ^-4 6.10X10 ^-4 68.2 # 7 DEME (30) The epoxy (5) 7.86X10 ^-4 5.71X10 ^-4 72.6 #8 alpha -terpineol (30) The epoxy (5) 4.15X10 ^-4 2.94X10 ^-4 70.8

Recovery by Solvent and Binder Addition.

^* R (%) = [ J _OR / J ₃ ] X100.

More specifically, in the case of the No. 1 sample without the binder and the No. 2 sample with the 1 wt% binder, the recovery rates after the creep removal were only 7.42% and 30.7%, respectively, Are expected to accompany. On the other hand, in the case of Sample No. 3 in which 3 wt% of binder was added, Sample No. 4 in which 5 wt% of binder was added, and Sample No. 5 in which 10 wt% of binder were added, creep removal And restored to 73.9%, 79.5% and 83.3%, respectively, and it is expected that fine patterns and pitches will be possible after printing. (68.2%, 72.6% and 70.8%, respectively) were obtained by using polyhydric alcohol solvents (EGME, DGME and α-terpineol) as the other solvents. From the above results, it was found that the effect of the binder on the restoration property is much larger than that of the solvent.

Then, the present inventors have tested the formation of fine patterns using the samples (FIGS. 5 to 7 and Table 4).

Sample menstruum( wt %) bookbinder( wt %) Adhesive class Resistivity (Ω? cm ) #One EG (35) - 0B 11.0 #2 EG (34) Epoxy (1) 0B 10.8 # 3 EG (32) Epoxy (3) 3B 9.2 #4 EG (30) The epoxy (5) 5B 14.1 # 5 EG (25) The epoxy (10) 5B 1000.4 # 6 EGME (30) The epoxy (5) 3B 112.2 # 7 DEME (30) The epoxy (5) 5B 11.5 #8 alpha -terpineol (30) The epoxy (5) 5B 13.8

Adhesive class and resistivity value with addition of solvent and binder.

First, the rheological characteristics and the amount of the binder (5 wt%) were fixed according to the amount of the binder, and then the rheological properties according to the types of the solvent were examined (Figs. 5A to 5C and Figs. 6A to 6C). As a result, Figs. 5A to 5C and Figs. 6A to 6C show formation of fine patterns depending on the amount of binder and the type of solvent, respectively, and all of them formed high resolution fine patterns. When the mask line width used was 30 μm, the deviation of the patterns in the shapes of the printed and sintered electrode patterns was too great, but the line patterns of 50-300 μm showed excellent printing patterns and resolution. However, improvement in the leveling property is required due to high viscosity and high elastic properties.

Finally, as can be seen from FIGS. 7A and 7B, the spreading phenomenon of the first and second samples was observed in a large number of patterns. In the case of the samples 3 and 4 in which 3 wt% and 5 wt% And showed fine pattern characteristics. However, in the case of the 5th sample to which the 10 wt% binder was added, the pattern was very poor due to the discharge problem in the mask mesh. In addition, through Table 4, as a result of the adhesion test (ASTM D3359; BYK, Germany) of the prepared conductive film / pattern, strong adhesion characteristics were shown as the binder amount increased. Electrical properties of the samples showed similar electrical properties up to samples with 5 wt% binder (1-4 samples). However, samples with 5 samples showed a decrease in electrical properties due to excessive binder addition (Table 4). In addition, from the viewpoints of overall functionality and printability, a sample containing 5% by weight of the binder exhibited the best properties, but it is expected that the leveling property due to high initial viscosity and viscoelasticity may be poor.

In addition, the adhesion test results of the conductive film / pattern prepared in Table 4 show that the conductive film prepared through the nano ink / paste containing diethylene glycol monoether (sample No. 7) and alpha-terpineol (sample No. 8) Showed very good adhesion class and electrical properties, while sample No. 6 using ethylene glycol monoether exhibited adhesive class (3B) and poor electrical properties. This is because, in the case of a solvent having a boiling point of 180 ° C or higher, the copper surface is prevented from being oxidized immediately upon thermal decomposition of the carbon coating layer during the sintering process, thereby contributing to necking and improvement of compactness. However, in a solvent having a relatively low boiling point Ether; 160 ° C), it is already almost lost at a temperature lower than the temperature at which the carbon coating layer is pyrolyzed to cause oxidation before the copper particles are necked together, which means that the copper particles do not contribute to neck formation. As a result, there arises a problem in the formation of necks between the copper particles, and accordingly, the contact area with the substrate is also reduced, and the adhesive property is reduced.

In conclusion, in consideration of the overall rheological properties, adhesive strength and electric conductivity, Sample No. 7 nano ink / paste containing 65 wt% of carbon-coated copper nanoparticles, 5 wt% of epoxy binder and 30 wt% of diethylene glycol monoether I was able to see that it was excellent.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It will be obvious. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (16)

60 to 70 wt% (wt%) of carbon coated metal nanoparticles; 25-35 wt% solvent; And 3-7% by weight of a binder. The ink or paste composition of claim 1, wherein the carbon-coated metal nanoparticles are metal nanoparticles having an amorphous carbon coating layer. The ink or paste composition according to claim 1, wherein the carbon-coated metal nanoparticles are 10-40 nm. The ink or paste composition of claim 1, wherein the metal nanoparticles are Cu, Ni, Fe, Al, Zn, Co, Au, Ag, Pt or combinations thereof. The ink or paste composition of claim 1, wherein the viscosity of the ink or paste composition is from about 40,000 to about 150,000 cps (centipoise). The ink or paste composition of claim 1, wherein the ink or paste composition does not comprise a dispersion stabilizer. The ink or paste composition of claim 1, wherein the solvent has a boiling point of at least 180 ° C. The ink or paste composition according to claim 1, wherein the solvent is an alcoholic or glycolic solvent. The method of claim 8, wherein the alcohol or glycol solvent is selected from the group consisting of alpha-terpineol, ethyl alcohol, methyl alcohol, isopropyl alcohol, Alcohols such as 2-methoxy ethanol, propyl alcohol, pentyl alcohol, hexyl alcohol, butyl alcohol and octyl alcohol; Or ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, ethylene glycol monomethyl ether (EGME), diethylene glycol monoether (DGME), propylene Propylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, triethylene glycol monomethyl ether (TGME), and propylene glycol methyl ether acetate. Glycols. ≪ / RTI > The ink or paste composition of claim 1, wherein the ink or paste composition forms a fine pattern through low temperature-sintering. 11. The method according to claim 10, wherein the low-temperature sintering is performed by oxidizing at 200 ° C to 250 ° C for 5 minutes to 30 minutes and then reducing at 200 ° C to 250 ° C for 5 minutes to 30 minutes. Ink or paste composition. 11. The ink or paste composition according to claim 10, wherein the fine pattern is formed in a range of 50 to 300 mu m. The ink or paste composition according to claim 1, wherein the ink or paste composition has a storage elastic modulus higher than a loss elastic modulus at a shear stress section lower than 50 Pa and a loss elastic modulus higher than a storage elastic modulus at a shear stress section at 50-1000 Pa . 13. A highly conductive fine patterned electrode comprising the ink or paste composition of any one of claims 1 to 13. 15. The electrode of claim 14, wherein the fine pattern is formed in the range of 50-300 [mu] m. 15. The electrode of claim 14, wherein the electrode has an electrical resistance value (? Cm) of less than 2.60 X 10 < ^-5 >.

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