KR101638989B1 - Composition for copper ink and method for forming conductive pattern using the same - Google Patents

Abstract

The copper ink composition comprises copper particles or copper precursors having a copper oxide film; And an azo compound containing a nitrogen double bond serving as a catalyst for reducing the copper oxide to copper by light.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper ink composition and a method for forming a conductive pattern using the copper ink composition.

The present invention relates to a copper ink composition and a conductive pattern forming method using the copper ink composition.

Currently, conductive inks used in printing electronics are silver inks or silver pastes containing mainly silver. In addition, conductive inks may include metal particles such as gold, platinum, and palladium.

Although such conductive inks are mainly used as conductive patterns for display panels, solar panels, and printed circuit boards, the price of silver contained in conductive inks is very high, which has a limitation that it is difficult to realize conductive patterns using conductive inks.

In recent years, techniques for realizing a conductive pattern using a conductive ink having low cost by including copper particles instead of silver particles in a conductive ink have been developed.

However, when a conductive pattern is formed using a conductive ink containing copper particles, a copper oxide film is easily formed on the surface of each copper particle contained in the conductive ink, which has a problem that the electric resistance of the conductive pattern becomes very high.

In order to prevent the copper oxide film from being formed on the surface of each copper particle, it is necessary to perform the firing at an elevated temperature of 500 ° C or higher for 1 hour to 3 hours under an inert gas atmosphere. When firing at a high temperature for a long time in an inert gas atmosphere, There is a problem that the production cost is further increased as compared with the conductive ink using the conductive ink.

Korean Patent Publication No. 10-2011-0125145 (2011.11.18) Water-based copper nano ink composition

The present invention provides a copper ink composition comprising a photocatalyst suitable for reducing a copper oxide film formed on the surface of copper particles to copper by simply providing light to the surface of copper particles at room temperature, and a method for forming a conductive pattern using the same.

In one embodiment, the copper ink composition comprises copper particles or copper precursors having a copper oxide film; And an azo compound containing a nitrogen double bond serving as a catalyst for reducing the copper oxide to copper by light.

The copper ink composition comprises a binder mixed with the copper particles; And a solvent for dissolving the binder.

The binder of the copper ink composition may be selected from the group consisting of a cellulose resin, a polyvinyl chloride resin, a copolymer resin, a polyvinyl alcohol resin, a polyvinylpyrrolidone resin, an acrylic resin, a vinyl acetate-acrylate copolymer resin, a butyral resin, An epoxy resin, a phenol resin, a rosin ester resin and a polyester resin, silicon, PVP and PVA.

The solvent of the copper ink composition may be at least one of a hydrocarbon solvent, a chlorinated hydrocarbon solvent, a cyclic ether solvent, a ketone solvent, an alcohol, a polyhydric alcohol solvent, an acetate solvent, an ether solvent of a polyhydric alcohol, .

The size of the copper particles or the copper precursor of the copper ink composition is nano or micro.

The copper precursor of the copper ink composition is _{CuCl, CuCl 2, Cu (acac} ) 2, Cu (hfac) 2, Cu (tfac) 2, Cu (dpm) 2, Cu (ppm) 2, Cu (fod) 2, Cu (acim) _2, and Cu including _{(nona-F) 2, Cu} (acen) 2, Cu (NO 3) ₂ · 3H ₂ 0 one of a, and CuSO ₄ · 5H ₂ O.

The azo compound of the copper ink composition comprises Azobis (isobutyronitrile) (AIBN).

In one embodiment, a method of forming a conductive pattern using a copper ink composition includes depositing copper particles or copper precursors having a copper oxide film and an azo containing nitrogen double bonds serving as a catalyst for reducing the copper oxide film to copper by light (azo) < / RTI >compound; Printing the copper ink composition on a substrate to form a preliminary conductive pattern; And forming the conductive pattern by providing the light to the preliminary conductive pattern to reduce the copper oxide layer formed on the surface of the copper particle or the copper precursor to the copper and sintering.

The forming of the conductive pattern may include a preliminary light irradiation step for preheating and drying the solvent; And a main light irradiation step for reducing and sintering the copper oxide film with the copper.

Wherein the light includes white light generated from a xenon flash lamp, the pulse width of the light is 0.01 ms to 100 ms, the pulse gap of the light is 0.1 ms to 100 ms, the number of pulses of the light is 1 to 1,000, The strength is from 1 J / cm 2 to 100 J / cm 2.

The copper ink composition according to the present invention and the method for forming a conductive pattern using the same may further include an azo compound having a nitrogen double bond in the copper ink composition to improve the reduction reaction of the copper oxide contained in the copper particles or the copper precursor, It is possible to select a wide range of binders to be contained and has the effect of enabling formation of a pattern at a low temperature using a copper ink composition.

1 is a flowchart showing a process of forming a conductive pattern using a copper ink composition according to an embodiment of the present invention.
2 is an SEM photograph of the conductive pattern formed by the condition 1 in Table 1. [
3 is an SEM photograph of a conductive pattern formed by the condition 2 of Table 1. [
4 is a SEM photograph of a conductive pattern formed by the condition 3 of Table 1. [
5 is an SEM photograph of the conductive pattern formed by the condition 4 in Table 1. [

In the following description, only parts necessary for understanding the embodiments of the present invention will be described, and the description of other parts will be omitted so as not to obscure the gist of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor is not limited to the meaning of the terms in order to describe his invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention, so that various equivalents And variations are possible.

In one embodiment of the present invention, the copper ink composition comprises copper particles or copper precursors formed with a copper oxide film, and an azo compound having a nitrogen double bond structure serving as a photoreducation catalyst capable of easily reducing copper oxide to light by light (azo composition).

Examples of the azo compound include Azobis (isobutyronitrile) (AIBN), and various azo compounds other than AIBN may be used.

For example, the azo compound may be azobenzene, azomethine, benzene azomethine, 4-phenyl azophenol, Tartrazine, Amaranth, amino azobenzene, azodicarboximide, azodicarbonamide, 4-dimethylaminoazobenzene, , 3-methoxy-4-amino azobenzene, ponceau MX, 4-amino azobenzene, and the like.

When the copper ink composition contains, for example, an azo compound such as AIBN, the azo compound serves as an initiator for the reduction of the copper oxide film formed on the copper particles and the copper precursor and the photoresist, so that the binder contained in the copper ink composition ). ≪ / RTI >

When the azo compound is contained in the copper ink composition and is out of the restriction of the type of the binder contained in the copper ink composition, a synthetic resin substrate such as polyimide, polyurethane, PMMA, PET or the like, a metal material such as stainless steel, It is possible to further improve the adhesion of the conductive pattern to a substrate and a non-metallic substrate such as indium tin oxide (ITO), ceramics, glass, silicon, etc., as well as to improve the printability of the conductive pattern formed using the copper ink composition and the high aspect ratio (high aspect ratio).

In addition, when the copper ink composition contains an azo compound such as AIBN, since it has high light sintering property at the same light amount in light sintering, a conductive pattern is formed on the substrate through the copper ink composition, Can be performed to prevent warpage or shrinkage of the substrate.

Further, when the copper ink composition contains an azo compound such as AIBN, it is possible to form a conductive pattern at a lower cost and further improve the electrical characteristics of the conductive pattern.

In one embodiment of the invention, the copper ink composition comprising an azo compound comprises copper particles or copper precursors, which act as conductors, a binder and a solvent.

The size of copper particles or copper precursors that serve as conductors in the copper ink composition may include nano size or micro size.

For example, the copper particles or copper precursors may be formed to a size of about 10 nm to about 500 nm, and preferably the size of the copper particles or copper precursor is about 40 nm to about 150 nm.

Copper precursor contained in the copper ink composition is _{CuCl, CuCl 2, Cu (acac} ) 2, Cu (hfac) 2, Cu (tfac) 2, Cu (dpm) 2, Cu (ppm) 2, Cu (fod) 2, It may include _{Cu (acim) 2, Cu (} nona-F) 2, Cu (acen) 2, Cu (NO 3) at least one of the ₂ · 3H ₂ 0 and CuSO ₄ · 5H ₂ O.

The binder contained in the copper ink composition containing the azo compound prevents dispersion of the copper particles and the copper precursor when the conductive pattern is formed using the copper ink composition and enables the conductive pattern to maintain excellent printability and high aspect ratio .

When the copper ink composition does not contain an azo compound, examples of the binder that can be contained in the copper ink composition include PVP and PVA. Alternatively, when an azo compound is included in the copper ink composition, a wide variety of binders as well as PVP or PVA can be used in the copper ink composition.

When the copper ink composition contains an azo compound, examples of the binder that can be contained in the copper ink composition include PVP and PVA, as well as PVC, cellulose resin, polyvinyl chloride resin, copolymer resin, polyvinyl alcohol resin, polyvinylpyrrolidone resin , Various resins such as acrylic resin, vinyl acetate-acrylate copolymer resin, butyral resin, alkyd resin, epoxy resin, phenol resin, rosin ester resin, polyester resin and silicone can be used.

Examples of the solvent included in the copper ink composition include a hydrocarbon solvent, a chlorinated hydrocarbon solvent, a cyclic ether solvent, a ketone solvent, an alcohol, a polyhydric alcohol solvent, an acetate solvent, an ether solvent of a polyhydric alcohol , Terpene type solvents, and the like.

Specifically, the solvent is selected from the group consisting of BCA (butyl carbitol acetate), BC (butyl carbitol), texanol, terpineol, BA (butyl acrylate), EA (athylacetate, ethyl acetate ), Ethylene glycol (EG), diethylene glycol, glycerol, cresol, MEK, acetone and the like.

Hereinafter, a method of forming a conductive pattern using a copper ink composition will be described.

1 is a flowchart showing a process of forming a conductive pattern using a copper ink composition containing an azo compound.

First, in order to form a conductive pattern on a substrate, a copper ink composition is first prepared (step S10)

In order to form the copper ink composition, copper particles, copper precursor, azo compound, binder, solvent, etc. serving as conductors are mixed with each other.

The size of the copper particles or copper precursor constituting the copper ink composition may be from about 10 nm to about 500 nm, and preferably the size of the copper particles or copper precursor may be from about 40 nm to about 150 nm.

Examples of materials that may be used as a copper precursor _{CuCl, CuCl 2, Cu (acac} ) 2, Cu (hfac) 2, Cu (tfac) 2, Cu (dpm) 2, Cu (ppm) 2, Cu (fod) 2, may include _{Cu (acim) 2, Cu (} nona-F) 2, Cu (acen) 2, Cu (NO 3) 2 · 3H 2 0 and CuSO ₄ · 5H ₂ O and the like.

The binder constituting the copper ink composition may contain not only PVP and PVA but also at least one selected from the group consisting of PVC, a cellulose resin, a polyvinyl chloride resin, a copolymer resin, a polyvinyl alcohol resin, a polyvinylpyrrolidone resin, an acrylic resin, a vinyl acetate- A butyral resin, an alkyd resin, an epoxy resin, a phenol resin, a rosin ester resin and a polyester resin.

The solvent constituting the copper ink composition may be selected from the group consisting of hydrocarbon solvents, chlorinated hydrocarbon solvents, cyclic ether solvents, ketone solvents, alcohols, polyhydric alcohol solvents, acetate solvents, ether solvents of polyhydric alcohols, And the like.

Specifically, the solvent is selected from the group consisting of BCA (butyl carbitol acetate), BC (butyl carbitol), texanol, terpineol, BA (butyl acrylate), EA (athylacetate, ethyl acetate ), Ethylene glycol (EG), diethylene glycol, glycerol, cresol, MEK, acetone and the like.

Copper particles or copper precursors, azo compounds, binders, and solvents that make up the copper ink composition are each primarily mixed in an optimized amount.

Subsequently, the materials constituting the copper ink composition were linearly dispersed by a line disperser for 30 minutes to 1 hour, and the linearly dispersed copper ink composition was again highly dispersed tertiary by a three-ply mill to form a copper ink composition The materials are thoroughly mixed, wherein the foreign material is filtered from the mixed copper ink composition to form a copper ink composition for finally forming a conductive pattern.

Once the copper ink composition is formed, a step of forming a preliminary conductive pattern using a copper ink composition on the substrate is performed. (Step S20)

Examples of the substrate on which the preliminary conductive pattern is formed include a synthetic resin substrate such as polyimide, polyurethane, PMMA, PET, etc., a metal substrate made of stainless steel, aluminum, gold, silver or the like and a metal substrate such as indium tin oxide (ITO) And the like.

The copper ink composition is coated or applied to the synthetic resin substrate, the metal substrate and the non-metal substrate by, for example, inkjet printing, flexographic / gravure ring printing, offset printing, dispensing printing and screen printing, A preliminary conductive pattern is formed on the synthetic resin substrate, the metal substrate, and the non-metal substrate.

The preliminary conductive pattern may be formed, for example, on the substrate to a thickness of about 4 占 퐉, and may be formed to have a width of 1 cm and a length of 2 cm, and the thickness, width, and length of the preliminary conductive pattern may be changed.

On the other hand, since the preliminary conductive pattern has a rich fluidity before being photo-sintered, the preliminary conductive pattern is formed on the substrate, and then the preliminary conductive pattern is dried for about 30 minutes at a temperature of, for example, A portion of the solvent is dried.

After the preliminary conductive pattern is formed on the substrate using the copper ink composition, a step of photo-sintering the preliminary conductive pattern by providing light to the preliminary conductive pattern to form a conductive pattern on the substrate is performed (step S30).

In order to form a conductive pattern on the substrate by photo-sintering the preliminary conductive pattern, light is provided to the preliminary conductive pattern formed on the substrate.

In one embodiment of the present invention, the light provided in the preliminary conductive pattern may comprise white light generated from a xenon flash lamp.

In one embodiment of the present invention, the reason why the white light generated in the preliminary conductive pattern is used as the white light generated from the xenon flash lamp is that the pulse width of the white light, the pulse gap, It is easy to adjust the intensity precisely.

Although it has been described in the embodiment of the present invention to provide white light generated from a xenon flash lamp to a preliminary conductive pattern, the preliminary conductive pattern may alternatively be provided with white light generated from various kinds of lamps.

The pulse width of the white light generated from the xenon flash lamp and provided to the preliminary conductive pattern may be from about 0.01 ms to about 100 ms and the pulse gap generated from the xenon flash lamp may be from about 0.1 ms to about 100 ms, The intensity of the white light may be about 1 J / cm 2 to about 25 J / cm 2.

In an embodiment of the present invention, when the pulse width of the white light is larger than 100 ms, the incident energy per unit time is reduced, and the light sintering efficiency may be lowered.

In addition, when the pulse gap is larger than 100 ms and the number of pulses is larger than 1,000, copper nano ink may not be sintered properly due to low energy of white light. In addition, if the pulse gap is less than 0.1 ms or the intensity of the white light is more than 100 J / cm 2, the damage or the life of the lamp may be shortened.

Particularly, when the intensity of the white light is about 1 J / cm 2 or less, the reduction reaction for reducing the copper oxide film formed on the surfaces of the copper particles and the copper precursor to copper is weak, so that the electric resistance characteristic of the conductive pattern may be deteriorated. On the contrary, when the intensity of the white light is about 25 J / cm 2 or more, high energy is provided to the substrate to cause shrinkage, warping and distortion of the substrate, and the preliminary conductive pattern and the substrate may be peeled off. However, in the case of a substrate having excellent mechanical strength by white light, the intensity of white light can be provided up to about 100 J / cm 2, which is larger than 25 J / cm 2.

The step of providing the preliminary conductive pattern with white light generated from the xenon flash lamp to form a conductive pattern may include the step of forming a conductive pattern in the preliminary conductive pattern by applying white light to the substrate in the pulse width range, So that the preliminary conductive pattern can be photo-sintered at a time.

Alternatively, the preliminary conductive pattern may be provided with multiple times of white light to form light sintering. Preferably, the preliminary conductive pattern is provided with twice the white light to perform the light sintering of the copper particles and the copper precursor contained in the preliminary conductive pattern have.

Specifically, after the preliminary light irradiation of the white light for the preheating of the preliminary conductive pattern, the texture densification and the solvent drying, the white light can be irradiated secondarily for sintering the copper particles or the copper precursor.

step Preheat Light sintering Sheet resistance
(Ω / sq) Line resistance
(Ω) Resistivity
(10 < ^-6 > cm) Condition energy
(J / cm2) Number of pulses
(time) time
(ms) energy
(J / cm2) Number of pulses
(time) time
(ms) One 2.5 One 20 15 One 20 0.04 0.08 16 2 2.5 One 20 15 One 15 0.02 01004 8 3 2.5 One 20 15 One 10 0.01 0.002 4 4 2.5 One 20 15 One 5 2.35 4.7 940

Referring to Table 1, in order to preheat the preliminary conductive pattern, densify the texture, and dry the solvent, the white light generated from the xenon flash lamp is irradiated to the preliminary conductive pattern for about 20 ms at an intensity of about 2.5 J / cm 2.

The white light, which is secondarily provided for the photo-sintering of the copper particles or the copper precursor, is then subjected to a preliminary conductive pattern for about 5 ms to about 20 ms at an energy of about 15 J / cm 2 to sinter the copper particles or copper precursor, The copper oxide film formed on the surface of the precursor is reduced to copper.

Thus, about 2 fold higher level conductive pattern formed by dividing into two to provide white light to the preliminary conductive pattern is about 4 × 10 ^-6 gatneunde the specific resistance of Ω㎝, which specific resistance of 1.68 × 10 ^-6 Ω㎝ of copper compared to The copper ink composition containing an azo compound has excellent electrical resistance characteristics.

2 is an SEM photograph of a conductive pattern formed by the first condition of Table 1, FIG. 3 is a SEM photograph of a conductive pattern formed by the second condition of Table 1, FIG. 4 is a SEM image of a conductive pattern formed by the third condition of Table 1 5 is an SEM photograph of a conductive pattern formed by the condition 4 in Table 1. Fig.

2 to 5, the preheating is performed for 20 ms at an energy intensity of 2.5 J / cm 2 and the light sintering is performed for 10 ms at an energy intensity of 15 J / cm 2, whereby the surface of the conductive pattern has a surface shape similar to that of a pure copper film It can be seen that it has excellent resistivity.

In one embodiment of the present invention, the white light generated from the xenon flash lamp is applied to the preliminary conductive pattern to form a conductive pattern on the substrate, and then the conductive pattern formed on the substrate by the hot air is heated to a temperature of about 70 캜 to about 100 캜 Dry hot air is provided to dry and remove the solvent remaining inside the conductive pattern formed on the substrate.

Alternatively, the solvent may be removed by adjusting the number of times or the intensity of the white light generated from the xenon flash lamp by two or three or more stages, without removing the solvent by using hot air generated by a hot air blower.

As described in detail above, the binder included in the copper ink composition can be selected in a wide variety of ways, including an azo compound having a nitrogen double bond in the copper ink composition to improve the reduction reaction of the copper oxide contained in the copper particles or the copper precursor And has a function of forming a pattern at a low temperature by using a copper ink composition.

It should be noted that the embodiments disclosed in the drawings are merely examples of specific examples for the purpose of understanding, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (4)

Copper particles formed with a copper oxide film having a particle size of 40 nm to 150 nm or copper precursors formed with the copper oxide film;
An azo compound containing a nitrogen double bond which acts as an initiator for reducing the copper oxide to copper by light and initiating a photoresist;
A binder mixed with the copper particles or the copper precursors to prevent scattering of the copper particles or the copper precursors and maintain a high aspect ratio; And
And a solvent for dissolving the binder,
The azo compound may be at least one selected from the group consisting of azobis (isobutyronitrile) (AIBN), azobenzene, azomethine, benzene azomethine, 4-phenyl azophenol, Tartrazine, Amaranth, amino azobenzene, azodicarboximide, azodicarbonamide, DAB dimethylaminoazobenzene), 3-methoxy-4-aminoazobenzene, ponceau MX and 4-aminoazobenzene,
The binder is selected from the group consisting of a cellulose resin, a polyvinyl chloride resin, a polyvinyl alcohol resin, a polyvinyl pyrrolidone resin, an acrylic resin, a vinyl acetate-acrylate copolymer resin, a butyral resin, an alkyd resin, An ester resin and a polyester resin, at least one of silicone, PVP and PVA,
The copper precursor _{CuCl, CuCl 2, Cu (acac} ) 2, Cu (hfac) 2, Cu (tfac) 2, Cu (dpm) 2, Cu (ppm) 2, Cu (fod) 2, Cu (acim) 2 _{, Cu (nona-F) 2} , Cu (acen) 2, Cu (NO 3) 2 · 3H 2 0 and CuSO ₄ · copper ink compositions include any of 5H ₂ O. The method according to claim 1,
Wherein the solvent comprises at least one of a hydrocarbon-based solvent, a chlorinated hydrocarbon-based solvent, a cyclic ether-based solvent, a ketone-based solvent, an alcohol, an acetate-based solvent and a terpene-based solvent. delete An azo compound containing a nitrogen double bond serving as an initiator for reducing the copper oxide to copper and acting as a photoresist initiator is mixed with copper particles on which a copper oxide film is formed or copper precursors on which the copper oxide film is formed by light, Preparing a copper ink composition comprising particles or a solvent which is mixed with the copper precursors to mix the binder to prevent scattering of the copper particles or the copper precursors and maintain a high aspect ratio, and to dissolve the binder;
Printing the copper ink composition on a substrate to form a preliminary conductive pattern; And
And providing the light to the preliminary conductive pattern to reduce and sinter the copper oxide or the copper oxide layer formed on the copper precursor to form a conductive pattern,
The step of forming the conductive pattern
A preliminary light irradiation step for preheating the preliminary conductive pattern; And
And a main light irradiation step for reducing and sintering the copper oxide film with the copper,
In the step of preparing the copper ink composition, the binder is selected from the group consisting of a cellulose resin, a polyvinyl chloride resin, a polyvinyl alcohol resin, a polyvinylpyrrolidone resin, an acrylic resin, a vinyl acetate-acrylate copolymer resin, a butyral resin, A resin, an epoxy resin, a phenol resin, a rosin ester resin and a polyester resin, at least one of silicone, PVP and PVA,
The azo compound may be at least one selected from the group consisting of azobis (isobutyronitrile) (AIBN), azobenzene, azomethine, benzene azomethine, 4-phenyl azophenol, Tartrazine, Amaranth, amino azobenzene, azodicarboximide, azodicarbonamide, DAB dimethylaminoazobenzene), 3-methoxy-4-aminoazobenzene, ponceau MX and 4-aminoazobenzene,
Wherein the light includes white light, the pulse width of the light is 0.01 ms to 100 ms, the pulse gap of the light is 0.1 ms to 100 ms, the number of pulses of the light is 1 to 1,000, the intensity of the light is 1 J / And the main light irradiation step irradiates the light for 5 ms to 20 ms.

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