KR20140056045A - Copper paste composition for printed electronics - Google Patents

Abstract

The present invention relates to a copper paste composition for printed electronics, and more specifically, to a copper paste composition for printed electronics which includes oxidation-suppressed copper nanoparticles and has improved electric conductivity, adhesion on a substrate, and printability. Specifically, the copper paste composition for printed electronics according to the present invention shows improved conductivity and printability at atmospheric pressure by using copper particles coated with organic materials or copper-hetero metal nanoparticles. Particularly, when the composition uses copper-hetero metal nanoparticles, the composition obtains improved adhesion, thereby being applied to various printed electronic fields by substituting for expensive silver particles.

Description

[0001] Copper paste composition for printing electronics [0002]

The present invention relates to a copper paste composition for printing electronics, and more particularly, to a copper paste composition for a printingelectronics that includes copper nanoparticles inhibited from oxidation and has excellent electrical conductivity, adhesion to a substrate, and printability.

Printed electronics technology is a technology to manufacture various electronic elements and parts or modules by using various functional ink materials which can process solution by direct printing process. It is used for RFID tags, lights, displays, solar cells , A battery, and the like can be applied to almost all areas where a semiconductor, a device, a circuit, and the like are used.

Of the ink materials used for such printing electrons, the conductive ink material is mainly used for electrodes and wiring of various electronic devices. The most important physical property required for the conductive line formed at this time is the conductivity, and the next important requirement is low process temperature, Low manufacturing cost and stability of ink. Conductive ink materials that are currently being used or actively studied include conductive polymer solutions, solutions in which metal nanoparticles are dispersed, carbon nanotube (CNT) dispersion solutions, and composite materials therefor.

Metal nanoparticles, which are currently being studied most actively, have high conductivity, but require relatively high firing temperatures (> 150 ° C.) to remove the dispersants used to disperse them, and the manufacturing cost is also high.

Until recently, such a metal ink paste has been mainly composed of a spherical micro (탆) size silver (Ag) composition, and the silver paste has been widely used since it is easy to produce and has excellent stability even after printing Since the price is high and the price is high, it has a bad influence on the unit price of the product, and spherical micro-silver particles have a disadvantage that it is difficult to realize a high electric conductivity at a low temperature.

In order to solve this problem, a paste composition composed of copper (Cu) capable of replacing silver at a high price in various printing processes and capable of being applied to existing processes has been increasingly attracted. However, There are disadvantages.

Accordingly, there is an urgent need to develop a copper paste composition which solves the problem of oxidization of the silver composition or copper composition, which has a high cost, and has improved adhesion to the lower substrate.

DISCLOSURE OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide a copper paste composition for a printing electron which is capable of exhibiting excellent electrical conductivity, adhesion, and printability by inhibiting oxidation of copper.

Another object of the present invention is to provide a printed electronic method capable of exhibiting excellent electrical conductivity, adhesion and printability by using the copper paste composition for a printingelectronic, and a printed electronic article produced by the method.

In order to achieve the above object,

a) 40 to 90% by weight of copper (Cu) nanoparticles, copper-dissimilar metal nanoparticles or mixtures thereof coated with an organic substance on the surface;

b) 1 to 30% by weight of a binder resin;

c) from 1 to 20% by weight of monomers and oligomers;

d) 0.1 to 3% by weight of a hardener; And

e) residual solvent

A copper paste composition for a printed wiring board.

The present invention also provides a printed electronic method, comprising printing a copper paste composition for printing electronics on a substrate, followed by drying and firing.

The present invention also provides a printed electronic article produced by the printed electronic method.

The copper paste composition for printing electronics according to the present invention can exhibit excellent conductivity and printability at atmospheric pressure by using copper nanoparticles, copper-dissimilar metal nanoparticles, or a mixture thereof, which are synthesized by wet synthesis and thinly coated with organic substances In particular, when copper-dissimilar metal nanoparticles are used, they can be applied to various printing electronic fields in place of expensive silver particles because of their excellent adhesive strength.

Fig. 1 is a photograph showing the copper nanoparticles synthesized in Synthesis Example 1. Fig.
2 is a graph showing the EDAX surface analysis results of the copper nanoparticles synthesized in Synthesis Example 1. FIG.
3 is a graph showing the results of thermal analysis and organic content measurement of the copper nanoparticles synthesized in Synthesis Example 1. FIG.
4 is a photograph showing the result of printing and firing the composition of Example 1 on a polyimide film.
5 is a photograph showing the result of evaluating the printability of the composition of Example 1. Fig.

The copper paste composition for printing capable of simultaneously drying and firing according to the present invention comprises: a) 40 to 90% by weight of copper (Cu) nanoparticles, copper-dissimilar metal nanoparticles or mixtures thereof coated with an organic substance on the surface; b) 1 to 30% by weight of a binder resin; c) from 1 to 20% by weight of monomers and oligomers; d) 0.1 to 3% by weight of a hardener; And e) a residual amount of a solvent.

The components will be described below.

a) Copper nanoparticles coated with organic material on the surface

Copper particles of 1 탆 or more, which are generally sold in the market, are difficult to realize low resistance due to difficulty of fusion between particles at a low temperature. When they are fused by heating for a long time, there is a disadvantage that the conductivity is completely lost while oxidation occurs first. In addition, commercially available copper particles are easily oxidized because there is no organic substance coated on the surface.

Copper nanoparticles coated with organic substances on the surface that can be used in the present invention can be coated with organic substances on pure copper nanoparticles, coated with organic substances on copper-dissimilar metal nanoparticles, or a mixture thereof. The dissimilar metal may be any metal as long as it is more readily oxidized than copper, which is commonly used in the art, but it is preferably zinc or aluminum. In addition, the pure copper nanoparticles do not exhibit excellent results even when the polymer component is added to the polyimide and the polymer substrate. Particularly, since the interface between the particles increases during firing and the contraction ratio increases, the shrinkage rate In the case of forming copper-dissimilar metal nanoparticles in the form of solid solution of zinc or aluminum in a solid form, it is possible to control the size of the interfacial boundary surface during the fusion between the particles, And the adhesive strength can be improved by reducing the difference in shrinkage ratio between the resin and the resin. In the copper-dissimilar metal nanoparticles, the content ratio of the copper to the dissimilar metal may be 1 to 30 parts by weight of the dissimilar metal with respect to 100 parts by weight of the copper.

In the present invention, the nanoparticles are spherical, have an average particle size of 50 to 1,000 nm, preferably 100 to 500 nm, and are coated with an organic material to inhibit oxidation. The copper nanoparticles according to the present invention are inhibited from being oxidized by the organic film coated on the surface even when heat is applied at atmospheric pressure where oxygen above a certain level exists.

The organic material may be an amine, a fatty acid, an aliphatic amine or a mercapto compound, and the content of surface organic matter is preferably 0.1 to 10% by weight. The desired electrical conductivity can be satisfied at the same time while preventing oxidation of copper.

The copper nanoparticles can be produced by a conventional method, for example, a wet synthesis method.

In the paste composition of the present invention, the copper nanoparticles may be contained in an amount of 40 to 90% by weight, and when added in an amount of less than 40% by weight, the binder content may be relatively high to make the desired conductivity impossible. There is a problem that the printing performance is remarkably deteriorated. Preferably, in the paste composition of the present invention, the copper nanoparticles may be mixed with 30 to 70 parts by weight of pure copper nanoparticles and 70 to 30 parts by weight of copper-dissimilar metal nanoparticles.

b) binder resin

The present invention includes a binder resin in order to impart adhesive power to the paste composition and rheological properties for printing.

Examples of the binder resin that can be used in the present invention include cellulose-based ones such as methylcellulose, ethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, Hydroxyethylcellulose, epoxy resin, polyester resin, and a copolymer prepared by mixing at least one of them.

In the present invention, the binder resin may be contained in an amount of 1 to 30% by weight, and when it is added in an amount of less than 1% by weight, the viscosity of the paste increases and the printing property becomes worse. When the content exceeds 30% by weight, The pattern spreads widely after printing, and the conductivity and dispersion stability after firing are lowered, resulting in poor storage stability.

c) a monomer or oligomer

In the present invention, a monomer or an oligomer is used to improve the viscosity characteristic of the composition.

The monomers and oligomers usable in the present invention may include at least one selected from the group consisting of acrylics, urethanes and epoxies, for example, urethane acrylates, polyfunctional acrylates, and polyester acrylate urethanes. Or less.

In the present invention, the monomer or oligomer may be contained in an amount of 1 to 20% by weight. When the amount of the monomer or oligomer is less than 1% by weight, the elasticity may be excessively increased by the binder. If the amount of the monomer or oligomer is more than 20% have.

d) Curing agent

Since the bonding force between the binder and the monomer and the oligomer alone can not be ensured in various printing electrons, it is possible to increase the adhesive strength by adding a curing agent capable of curing by thermo-plasticization.

As the curing agent usable in the present invention, dimethylaminopropyl methacrylamide, isocyanate, phthalic anhydride and the like can be used.

In the present invention, the curing agent may be included in an amount of 0.1 to 3% by weight. When the amount of the curing agent is less than 0.1% by weight, curing is not sufficiently carried out and it is difficult to secure the adhesive strength. You can knock.

e) Solvent

In the present invention, a solvent is used to control the viscosity of the paste and to enhance dispersion of nanoparticles.

Examples of the solvent usable in the present invention include diethylene glycol, triethylene glycol, tetraethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether acetate, methylpyrrolidone, terpinol and the like can be used, ≪ / RTI >

In addition, the copper paste composition for printing electronics of the present invention may further contain additives commonly used in the art, for example, an antioxidant, a pH adjuster, etc., in addition to the above components.

The present invention also provides a printed electronic method comprising printing the copper paste composition for printing electronics on a substrate, followed by drying and firing, and a printed electronic article made according to the method.

In the printing electronic method according to the present invention, a variety of commonly used printing processes can be applied. For example, the printing may be screen printing, gravure off-set printing, gravure direct ) Printing, imprinting and the like, preferably screen printing. The substrate to be printed may be a variety of known substrates, for example, a flexible circuit board, a glass substrate, or the like. Preferably, the substrate is a flexible circuit board, particularly a polyimide (PI) film.

The paste composition of the present invention is preferably optimized for each printing process. When a screen printing method is applied to a polyimide (PI) film, the paste composition of the present invention has a viscosity range of 10,000 to 50,000 centipoise .

The copper paste composition of the present invention may be fired according to a firing method commonly used in the art after performing the printing process as described above. Preferably, the copper paste composition may include nitrogen, oxygen or argon hot air alone, middle infra red (MIR) Lamps, or hot air and MIR lamps at the same time.

Specifically, it is preferable that the composition according to the present invention is dried and fired while supplying hot nitrogen or oxygen at a temperature of 220 ° C or less, preferably 150 to 200 ° C, or dried and fired at 150-200 ° C with an MIR lamp.

The general copper paste composition is easily oxidized to atmospheric pressure. On the other hand, the composition according to the present invention can suppress oxidation at atmospheric pressure as much as possible by using copper nanoparticles coated with an organic substance on the surface, thereby providing excellent electrical conductivity, It can be applied to various printing electronic fields (for example, RFID tags, lights, displays, solar cells, batteries, semiconductors, electronic devices, circuits, etc.) instead of expensive silver particles. And can be preferably applied particularly in the manufacture of a flexible circuit board.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

Synthesis Example 1: Synthesis of pure copper nanoparticles

22.3 g of triethylamine was added to an aqueous solution obtained by dissolving 30 g of copper precursor CuCl ₂ as a metal precursor in 450 ml of water, and forced stirring was performed until the green mixed solution turned into a gel-like pale green substance. 27.5 g of hydrazine was slowly added thereto, and forced stirring was performed until the solution turned dark red or dark red. The reaction temperature was kept at 45 캜.

After centrifugation and precipitation, the reddish powder was recovered and washed repeatedly with methanol and collected, and then stored at atmospheric pressure.

As a result of observing the copper nanoparticles prepared above, as shown in FIG. 1, the copper nanoparticles produced were spherical with 100-120 nm. Also, as a result of EDAX surface analysis, it was confirmed that the copper particles were almost free of copper oxide as shown in Fig.

As a result of the measurement of the organic content of the surface through the thermal analysis with blowing of air, the organic matter content was measured to be about 2% as shown in FIG. 3. As shown in FIG. 3, .

Synthesis Example 2: Synthesis of copper-zinc nanoparticles

Copper-zinc nanoparticles were synthesized in the same manner as in Synthesis Example 1 except that 27 g of copper precursor CuCl ₂ and 3 g of zinc precursor were used instead of 30 g of copper precursor CuCl ₂ as a metal precursor.

Synthesis Example 3: Synthesis of copper-aluminum nanoparticles

Copper-aluminum nano-particles were synthesized in the same manner as in Synthesis Example 1 except that 27 g of copper precursor CuCl ₂ and 3 g of aluminum precursor were used instead of 30 g of copper precursor CuCl ₂ as a metal precursor.

Example 1: Preparation of Copper Paste Composition for Printed Electronics

10 g of ethylcellulose polymer, 72 g of terpinol as a solvent and 18 g of butyl carbitol were added to the reactor, and the mixture was stirred at 65 DEG C until the resin was completely dissolved. When the resin was completely dissolved, 8 g of the binder resin was added to 30 g of the copper nanoparticles prepared in Synthesis Example 1, and the mixture was stirred at a constant speed using a paste mixer until complete mixing. 2.6 g of dipentaerythritoltritol hydroxypentaacrylate (DPHA) among the acrylic monomers having three or more functional groups was added to the thus-prepared copper paste, and a radical hardening agent capable of generating radicals at a temperature lower than 200 캜 to be thermally cured 0.2 g. Followed by further stirring for about 1 minute to complete the paste composition.

Example 2: Preparation of Copper Paste Composition for Printed Electronics

A paste composition was prepared in the same manner as in Example 1, except that 30 g of the copper-zinc nanoparticles prepared in Synthesis Example 2 was used instead of 30 g of the copper nanoparticles prepared in Synthesis Example 1.

Example 3: Preparation of Copper Paste Composition for Printed Electronics

Except for using 15 g of the copper nanoparticles prepared in Synthesis Example 1 and 15 g of the copper-zinc nanoparticles prepared in Synthesis Example 2 instead of 30 g of the copper nanoparticles prepared in Synthesis Example 1, To prepare a paste composition.

Example 4: Preparation of Copper Paste Composition for Printed Electronics

Except that 15 g of the copper nanoparticles prepared in Synthesis Example 1 and 15 g of the copper-aluminum nano-particles prepared in Synthesis Example 3 were used instead of 30 g of the copper nanoparticles prepared in Synthesis Example 1, To prepare a paste composition.

Example 5: Preparation of Copper Paste Composition for Printed Electronics

A paste composition was prepared in the same manner as in Example 1, except that a polyfunctional urethane acrylate-based oligomer having a molecular weight of 2,000 or more was used instead of the acryl-based monomer.

Example 6: Preparation of Copper Paste Composition for Printing Electronics

A paste composition was prepared in the same manner as in Example 1, except that a bisphenol-based epoxy oligomer having a molecular weight of 500 or more was used in place of the acrylic-based monomer.

Example 7: Preparation of Copper Paste Composition for Printing Electronics

A paste composition was prepared in the same manner as in Example 1 except that 8 g of the ethylcellulose polymer and 2 g of the epoxy resin were used instead of 10 g of the ethylcellulose polymer.

Example 8: Preparation of Copper Paste Composition for Printed Electronics

A paste composition was prepared in the same manner as in Example 1, except that 8 g of the ethylcellulose polymer and 2 g of the epoxy resin were used in place of 10 g of the ethylcellulose polymer and a urethane-based monomer was used in place of the acryl-based monomer.

Example 9: Preparation of Copper Paste Composition for Printed Electronics

A paste composition was prepared in the same manner as in Example 1 except that 8 g of the ethylcellulose polymer and 2 g of the epoxy resin were used instead of 10 g of the ethylcellulose polymer and an epoxy-based monomer was used instead of the acrylic-based monomer.

Example 10: Preparation of Copper Paste Composition for Printed Electronics

15 g of the copper nanoparticles prepared in Synthesis Example 1 and 15 g of the copper-zinc nanoparticles prepared in Synthesis Example 2 were used in place of 30 g of the copper nanoparticles prepared in Synthesis Example 1, A paste composition was prepared in the same manner as in Example 1 except that the monomers were used.

Example 11: Preparation of Copper Paste Composition for Printed Electronics

15 g of the copper nanoparticles prepared in Synthesis Example 1 and 15 g of the copper-zinc nanoparticles prepared in Synthesis Example 2 were used in place of 30 g of the copper nanoparticles prepared in Synthesis Example 1, A paste composition was prepared in the same manner as in Example 1 except that the monomers were used.

Example 12: Preparation of Copper Paste Composition for Printed Electronics

Except that 15 g of the copper nanoparticles prepared in Synthesis Example 1 and 15 g of the copper nanoparticles prepared in Synthesis Example 1 were used instead of 10 g of the ethylcellulose polymer and 8 g of the ethylcellulose polymer and 2 g of the epoxy resin, A paste composition was prepared in the same manner as in Example 1, except that 15 g of copper-zinc nanoparticles prepared in Example 2 were used.

Example 13: Preparation of Copper Paste Composition for Printed Electronics

Except that 15 g of the copper nanoparticles prepared in Synthesis Example 1 and 15 g of the copper nanoparticles prepared in Synthesis Example 1 were used instead of 10 g of the ethylcellulose polymer and 8 g of the ethylcellulose polymer and 2 g of the epoxy resin, A paste composition was prepared in the same manner as in Example 1, except that 15 g of the copper-zinc nanoparticles prepared in Example 2 were used and a urethane-based monomer was used instead of the acryl-based monomer.

Example 14: Preparation of Copper Paste Composition for Printed Electronics

Except that 15 g of the copper nanoparticles prepared in Synthesis Example 1 and 15 g of the copper nanoparticles prepared in Synthesis Example 1 were used instead of 10 g of the ethylcellulose polymer and 8 g of the ethylcellulose polymer and 2 g of the epoxy resin, A paste composition was prepared in the same manner as in Example 1, except that 15 g of the copper-zinc nanoparticles prepared in Example 2 were used and an epoxy-based monomer was used instead of the acryl-based monomer.

Comparative Example 1: Production of copper paste composition for printing electronics

A paste composition was prepared in the same manner as in Example 1, except that 30 g of copper particles purchased from Aldrich Co. were used instead of 30 g of the copper nano particles prepared in Synthesis Example 1.

Test Example 1

For evaluation of the physical properties of the copper paste compositions prepared in Examples 1 to 14 and Comparative Example 1, each composition was printed on a polyimide film through a 290 mesh screen net with patterns formed, and the formed film was dried at 50 DEG C After conducting baking with hot air for 3 minutes at 200 ° C (FIG. 4), the conductivity was directly measured on a pattern printed with a multitester, and the printed pattern was evaluated for adhesion by the method of ASTM D3359. Table 1 shows the results.

The printability was evaluated at 50/50, 70/70, 90/90, 110/110 (line width / void space), and the results are shown in the following Table 1 and FIG. 5 (composition of Example 1). "O" indicates that there is no disconnection, and "x" indicates disconnection.

conductivity
(Line resistance
100 탆 / 1 cm) Adhesion
(PI substrate
ASTM D3359) Printability
(50 占 퐉 breakage oil / no) Example 1 2.5 50 o Example 2 7.8 95 o Example 3 3.4 90 o Example 4 30.2 95 o Example 5 3.9 50 o Example 6 10.5 95 o Example 7 3.1 50 o Example 8 3.9 90 o Example 9 11.8 50 o Example 10 4.8 30 o Example 11 20.4 95 o Example 12 3.8 50 o Example 13 4.9 90 o Example 14 20.8 90 o Comparative Example 1 x 5 x

As shown in Table 1, it was confirmed that the copper paste compositions of Examples 1 to 14 according to the present invention had excellent conductivity, adhesion, and printability as compared with compositions using commercial copper nanoparticles.

Particularly, when the copper-dissimilar metal nanoparticles were used in the same composition, the adhesion was greatly increased, and the copper-zinc nanoparticles showed the greatest effect on the lower adhesion.

Claims (17)

a) 40 to 90% by weight of copper (Cu) nanoparticles, copper-dissimilar metal nanoparticles or mixtures thereof coated with an organic substance on the surface;
b) 1 to 30% by weight of a binder resin;
c) from 1 to 20% by weight of monomers and oligomers;
d) 0.1 to 3% by weight of a hardener; And
e) residual solvent
Wherein the copper paste composition for printing electronics is a copper paste composition for a printed wiring board. The method according to claim 1,
Wherein the nanoparticles have an average particle size of 50 to 1,000 nm. The method according to claim 1,
Wherein the dissimilar metal is zinc or aluminum. The method according to claim 1,
Wherein the copper-dissimilar metal is mixed with 1 to 30 parts by weight of a dissimilar metal to 100 parts by weight of copper. The method according to claim 1,
Wherein the organic substance is an amine. The method according to claim 1,
Wherein the organic material is 0.1 to 4% by weight of the particles. The method according to claim 1,
Wherein 30 to 70 parts by weight of the pure copper nanoparticles coated with the organic material and 100 to 30 parts by weight of the copper-dissimilar metal nanoparticles coated with the organic material are mixed in an amount of 100 parts by weight, Paste composition. The method according to claim 1,
Wherein the binder resin is at least one selected from the group consisting of a cellulose-based resin, an epoxy-based resin, a polyester-based resin, and a copolymer prepared by mixing at least one of the foregoing resins. The method according to claim 1,
Wherein the monomer and oligomer are at least one selected from the group consisting of an acrylic type, a urethane type, and an epoxy type. The method according to claim 1,
Wherein the curing agent is at least one selected from the group consisting of dimethylaminopropyl methacrylamide, sisocyanate, phthalic anhydride, and the like. The method according to claim 1,
Wherein the solvent is selected from the group consisting of diethylene glycol, triethylene glycol, tetraethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl Characterized in that it is at least one selected from the group consisting of ether, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether acetate, methylpyrrolidone, terpinol and mixtures thereof. / RTI > A method for electronic printing comprising the steps of: printing on a substrate a copper paste composition for a printing electron according to claim 1, followed by drying and firing. 13. The method of claim 12,
Wherein the substrate is a polyimide film. 13. The method of claim 12,
Wherein the printing is a screen printing. 13. The method of claim 12,
Wherein the firing is performed at 150-200 占 폚. An electronic printing article produced by the electronic printing method according to claim 12. 17. The method of claim 16,
Wherein the electronic printing article is a flexible circuit board.

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