KR101088723B1 - Conductive paste comprising metal nanoparticle-deposited carbon nanostructure and preparation method thereof - Google Patents

Abstract

Disclosed are a conductive paste including a carbon nanostructure on which metal nanoparticles are deposited, and a method of manufacturing the same. The conductive paste may include a carbon nanostructure in which metal nanoparticles functionalized with a compound having a phenyl ring and a thiol group are deposited; Conductive particles; And a binder. The conductive paste is very excellent in electrical conductivity and can be applied to electronic and electrical component packaging, conductive interconnector, etc., and also various applications are possible compared to conventional conductive pastes.

Conductive Paste, Carbon Nanostructures

Description

Conductive paste comprising carbon nanostructures on which metal nanoparticles are deposited, and a method of manufacturing the same {CONDUCTIVE PASTE COMPRISING METAL NANOPARTICLE-DEPOSITED CARBON NANOSTRUCTURE AND PREPARATION METHOD THEREOF}

The present invention relates to a conductive paste including a carbon nanostructure on which metal nanoparticles are deposited, and a method of manufacturing the same.

In general, a conductive paste is an adhesive having electrical conductivity used for wiring assembly of electrical / electronic products or circuits, and refers to a paste that is blended and composed of conductive particles such as binders such as polymer resins and Ag particles. This conductive paste is a connection material that can replace the solder paste traditionally used in the reflow soldering process for electronics assembly, and utilizes the existing reflow process equipment, while mounting the assembly at a lower process temperature than the conventional soldering process temperature. You can do that.

BACKGROUND OF THE INVENTION Conductive pastes composed of metal powders and binders have been widely used in the field of electrical and electronics as electronic component packaging and circuit interconnectors. However, the resistivity of the conductive paste currently used is 5 × 10 ⁻⁴ to 5 × 10 ⁻⁵ Ω · cm, which does not reach the resistivity of the metal. Therefore, the efficiency in terms of electrical conductivity and thermal conductivity is low, there is a limit to the application field.

It is an object of the present invention to provide a conductive paste having improved electrical conductivity including a carbon nanostructure on which metal nanoparticles are deposited, and a method of manufacturing the same.

According to an aspect of the present invention, a carbon nanostructure in which metal nanoparticles functionalized with a compound having a phenyl ring and a thiol group are deposited; Conductive particles; And a conductive paste comprising a binder.

According to an embodiment of the present invention, the compound having a phenyl ring and a thiol group is benzyl mercaptan, benzenethiol, triphenylmethanethiol, bromobenzyl mercaptan, It may be selected from the group consisting of aminothiophenol and 2-phenylethanethiol.

According to one embodiment of the present invention, the metal nanoparticles may be nanoparticles of a metal selected from the group consisting of Au, Pt, Ag, Cu, Ni and Ru.

According to one embodiment of the present invention, the carbon nanostructure may be selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes and graphene.

According to an embodiment of the present invention, the carbon nanostructures on which the metal nanoparticles functionalized with the phenyl ring and the thiol group are deposited may be 15 wt% to 85 wt% of the deposited metal nanoparticles. It may be to include.

According to one embodiment of the invention, the conductive particles may be a powder of a metal selected from the group consisting of Au, Pt, Ag, Cu, Ni and Ru.

According to an embodiment of the present invention, the binder may include an epoxy resin.

According to an embodiment of the present invention, 0.5 to 15 parts by weight of the carbon nanostructures on which the metal nanoparticles are deposited; 50 to 90 parts by weight of the conductive particles; And 1 to 49.5 parts by weight of the binder.

According to an embodiment of the present invention, the metal nanoparticles may include 0.5 to 3 parts by weight of the carbon nanostructures deposited thereon.

According to one embodiment of the present invention, the conductive paste may have a resistivity of 5 X 10 ^-4 to 2 X 10 ^-6 Pa · cm after curing.

According to another aspect of the invention, the step of preparing a colloid of functionalized metal nanoparticles by mixing a compound having a phenyl ring and a thiol group with a metal precursor solution; Preparing a carbon nanostructure on which the metal nanoparticles are deposited by mixing the colloid of the functionalized metal nanoparticles with a solution in which the carbon nanostructures are dispersed; And mixing the conductive particles and the binder with the carbon nanostructure on which the metal nanoparticles are deposited.

According to an embodiment of the present invention, in the manufacturing of the carbon nanostructures on which the metal nanoparticles are deposited, ultrasonication may be performed when the colloid of the functionalized metal nanoparticles is mixed with a solution in which the carbon nanostructures are dispersed. have.

The conductive paste according to the preferred embodiment of the present invention is very excellent in electrical conductivity compared to the commercially available conductive paste. Therefore, it can be applied to electronic and electrical component packaging, conductive interconnector, etc., and also various applications are possible compared to the conventional conductive paste.

Hereinafter, a conductive paste including a carbon nanostructure on which metal nanoparticles according to the present invention are deposited, and a method of manufacturing the same will be described in detail.

The conductive paste according to the present invention comprises: (1) carbon nanostructures on which metal nanoparticles functionalized with a compound having a phenyl ring and a thiol group are deposited; (2) conductive particles; And (3) a binder.

When the carbon nanostructures on which metal nanoparticles are deposited are applied to a conductive paste according to the present invention, the carbon nanostructures on which the metal nanoparticles are deposited form an electrical network between the metal particles in the conductive paste. In addition, the metal nanoparticles are sintered with the metal particles on the surface of the carbon nanostructure when cured at 250 ° C. or lower, thereby greatly reducing the contact resistance between the carbon nanostructure and the metal particles, thereby facilitating the flow of electrons, thereby leading to the conductivity of the paste. Improvements are possible.

Hereinafter, each component will be described.

Carbon nanostructures, such as carbon nanotubes and graphene, have excellent mechanical and electrical properties due to their unique structural characteristics, and various applications of energy, electrical, electronic, and structural materials have been attempted. However, the carbon nanostructures are very small in size and poor in affinity with other materials, and thus are applied after chemical and physical functionalization to the surface. Particularly, in the case of metal particle deposition on carbon nanostructures, chemical vapor deposition, electrolytic and electroless coating methods are mostly used to make it difficult to control a large amount of processes and deposition amount, and to deposit carbon nanostructures on the surface of the carbon nanostructures. By physically and chemically generating defects, the intrinsic properties of carbon nanostructures tend to be deteriorated.

In order to solve this problem, the present invention uses a carbon nanostructure on which functionalized metal nanoparticles are deposited. Functionalization of the metal nanoparticles may be preferably made by a compound having a phenyl ring and a thiol group.

The carbon nanostructure in which the functionalized metal nanoparticles are deposited may serve as an electrical bridge between the conductive particles in the conductive paste.

In a preferred embodiment of the present invention, the metal nanoparticles may be prepared by using a chemical including a phenyl ring and a thiol group, and may be physically and chemically bound to the carbon nanostructure.

When manufacturing metal nanoparticles using a compound containing a phenyl ring and a thiol group, it is very easy to prevent agglomeration between metal nanoparticles and to control particle size, and the produced metal nanoparticles are formed of carbon nanostructures by a phenyl ring on a surface thereof. Π-π bonding is possible with the surface.

Compounds having a phenyl ring and a thiol group are benzyl mercaptan, benzenethiol, triphenylmethanethiol, bromobenzyl mercaptan, aminothiophenol, 2- It may be a compound such as phenyl ethanethiol (2-phenylethanethiol), if the compound having a phenyl ring and a thiol group at the same time is not particularly limited. Preferably benzyl mercaptan can be used.

The metal nanoparticles may be nanoparticles of metals such as Au, Pt, Ag, Cu, Ni, and Ru, and may also use two or more kinds together. Preferably silver nanoparticles can be used.

The carbon nanostructure is not particularly limited as long as it is a carbon nanostructure forming a hexagonal carbon structure on a surface thereof, and preferably may be a single-wall carbon nanotube, a multi-wall carbon nanotube, graphene, or the like. Preferably it is a multi-walled carbon nanotube.

Deposition of the functionalized metal nanoparticles to the carbon nanostructures may be performed in various ways, but preferably, a colloidal solution of the functionalized metal nanoparticles and a carbon nanostructure dispersed therein is mixed and ultrasonically By treatment.

For the carbon nanostructures, the deposited amount of the functionalized metal nanoparticles is preferably 15% to 85% by weight, most preferably about 65% by weight.

The conductive particles may be used without particular limitation so long as they are metal powders having excellent electrical conductivity which can be used for general conductive pastes. For example, metal powders such as Au, Pt, Ag, Cu, Ni, and Ru may be used as the conductive particles, and two or more kinds thereof may be used in combination. Preferably Ag powder can be used.

The binder may be used without particular limitation as long as it is a resin that can be used for a general conductive paste. For example, a resin having a thermosetting, photosetting or both properties may be used. Specific examples include epoxy resins, phenol resins, polyester resins, polyimide resins, acrylic resins, urethane resins, silicone resins, and the like. Such a resin may be included in the form of a monomer in the conductive paste. The binder may include a thermal curing agent or a photocuring agent, it is also possible to use two or more kinds of curing agents in combination. In addition, the binder may include an organic solvent.

According to a preferred embodiment of the present invention, the conductive paste is 0.5 to 15 parts by weight of the carbon nanostructures on which the metal nanoparticles are deposited; 50 to 90 parts by weight of the conductive particles; And 1 to 49.5 parts by weight of the binder. It may not be easy to obtain the adhesion and conductivity as the conductive paste in the numerical range. More preferably, the conductive paste is 0.5 to 3 parts by weight of the carbon nanostructures on which the metal nanoparticles are deposited; 75 to 85 parts by weight of the conductive particles; And 10 to 24.5 parts by weight of the binder.

According to a preferred embodiment of the present invention, the conductive paste may be cured at a temperature of 120 ℃ to 250 ℃, the specific resistance after curing may be in the range of 5 X 10 ^-4 to 2 X 10 ^-6 Ω · cm (If the metal nanoparticles and the conductive particles are Ag). During the curing process, the nano metal particles deposited on the surface of the carbon nanostructures may be sintered with the surrounding conductive particles to greatly reduce the contact resistance between the carbon nanostructures and the conductive particles (see FIG. 4).

The method for producing the above-mentioned conductive paste is described below.

The conductive paste according to the present invention comprises the steps of: (1) preparing a colloid of functionalized metal nanoparticles by mixing a compound having a phenyl ring and a thiol group with a metal precursor solution; (2) mixing the colloid of the functionalized metal nanoparticles with a solution in which the carbon nanostructures are dispersed to prepare a carbon nanostructure on which the metal nanoparticles are deposited; And (3) mixing the conductive particles and the binder with the carbon nanostructures on which the metal nanoparticles are deposited.

First, a compound having a phenyl ring and a thiol group is mixed with a metal precursor solution such as metal nitride (eg, AgNO ₃ ) to prepare a colloid of metal nanoparticles in which the phenyl ring is functionalized.

The metal nanoparticles having the phenyl ring functionalized in the colloidal state are mixed with a solution in which the carbon nanostructures are dispersed. Preferably, the sonication during the mixing may induce metal particles to be deposited on the surface of the carbon nanostructures.

In this case, the deposition amount of the metal nanoparticles can be controlled by the amount of the metal nanoparticles mixed with the carbon nanostructure, and the size of the metal nanoparticles can be controlled by the concentration of the compound containing a phenyl ring and a thiol group.

The obtained carbon nanostructure on which the metal nanoparticles are deposited is uniformly mixed with the binder and the conductive particles in an appropriate ratio to prepare a conductive paste.

Hereinafter, the present invention will be described in more detail with reference to the following examples.

Example

benzyl With mercaptan  Functionalized Ag  Synthesis of Nanoparticles

AgNO ₃ was reduced in the presence of benzyl mercapdan to synthesize Ag nanoparticles functionalized with benzyl mercaptan (see FIG. 1). A benzyl mercaptan solution (0.18 mol·L ⁻¹ ) prepared by mixing 100 ml of ethanol and 1.18 ml of benzyl mercaptan was added to AgNO _3. A white Ag colloid was obtained by mixing together 0.3 ml of 100 ml ethanol in a molar ratio of benzyl mercaptan to Ag of 7.2: 1. After about 48 hours of strong stirring using a magnetic stirrer (Magnetic Stirrir), the solution turned dark brown, and Ag nanoparticles functionalized with benzyl mercaptan were synthesized.

Functionalized Ag  Deposition on Carbon Nanotubes of Nanoparticles

50 mg of thin multi-walled carbon nanotubes (Thin-MWNTs) were mixed with 400 ml of ethanol and ultrasonic waves (42 kHz, 560 W) were added for 20 minutes. After mixing 100 ml of the functionalized Ag nanoparticle solution prepared above, ultrasonic wave (42 kHz, 560 W) was added for 10 minutes, and ultrasonic wave was applied for 8 hours with a bath type sonicator (42 kHz, 135 W). . Thereafter, the solution was washed with ethanol and filtered to obtain carbon nanotubes on which Ag nanoparticles were deposited. Through the change of reaction conditions, the amount of Ag nanoparticles deposited in the carbon nanotubes on which the Ag nanoparticles were deposited was 15 wt%, 30 wt%, 65 wt%, and 85 wt%, respectively. Obtained.

Preparation of Conductive Paste

The conductive paste was prepared by mixing the obtained carbon nanotubes on which the functionalized Ag nanoparticles were deposited with the conductive particles and the binder. Ag powder was used as the conductive particles, and a conventional binder containing an epoxy resin, a small amount of a thermal curing agent and a solvent was used as the binder. The conductive particles and the binder were used in an appropriate weight ratio (about 4: 1 to 5: 1) as a conventional conductive paste, and a conductive paste was prepared by changing the carbon nanotubes on which Ag nanoparticles were deposited from 0.5 to 3.0 wt%.

Comparative example

A conductive paste containing no carbon nanotubes on which functionalized Ag nanoparticles were deposited was prepared. Ag powder was used as the conductive particles, and a mixture of an epoxy resin, a small amount of a thermal curing agent, and a solvent was used as the binder.

Test Example

After the conductive pastes prepared in Examples and Comparative Examples were heated and thermally cured, the specific resistance was measured.

The amount of Ag nanoparticles deposited on the carbon nanotubes (CNT) is 15 wt%, 30 wt%, 65 wt%, and 85 wt%, respectively. Table 1 shows the results of measuring the specific resistance of the conductive paste containing the weight%. The resistivity of the conductive paste was lowest when the amount of deposited Ag nanoparticles was about 65%.

[Table 1]

division Specific resistance (Ωcm) Control group (Comparative example: no Ag-CNT) 5.55 X 10 ^-5 1.0% by weight of Ag-CNT (15% by weight of deposited Ag) 2.58 X 10 ^-5 1.0% by weight of Ag-CNT (30% by weight of deposited Ag) 1.41 X 10 ^-5 1.0% by weight of Ag-CNT (65% by weight of deposited Ag) 7.82 X 10 ^-6 1.0% by weight of Ag-CNT (85% by weight of deposited Ag) 1.12 X 10 ^-5

The weight ratio of the carbon nanotubes on which the functionalized Ag nanoparticles were deposited was 0.5 to 3.0% by weight based on the amount of Ag nanoparticles deposited on the carbon nanotubes (Ag-CNT) on which the functionalized Ag nanoparticles were deposited. The specific resistance was measured after the thermosetting of the conductive paste prepared by changing to. As a result, the percolation threshold level was observed at about 1.5% by weight, and the resistivity tended to increase when the weight ratio of the carbon nanotubes on which Ag nanoparticles were deposited exceeds 3.0% by weight. . The experimental results are shown in Table 2 below and FIG. 5.

TABLE 2

division Specific resistance (Ωcm) Control (Comparative) Ag-CNT 0 wt% 5.55 X 10 ^-5 Ag-CNT (65% by weight of deposited Ag) 0.5% by weight 9.28 X 10 ^-6 1.0% by weight of Ag-CNT (65% by weight of deposited Ag) 7.81 X 10 ^-6 Ag-CNT (Deposited Ag 65% by weight) 1.5% by weight 5.0 X 10 ^-6 Ag-CNT (Deposited Ag 65% by weight) 2.0% by weight 4.57 X 10 ^-6 Ag-CNT (65% by weight of deposited Ag) 3.0% by weight 1.36 X 10 ^-5

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention. Many embodiments other than the above-described embodiments are within the scope of the claims of the present invention.

1 is a schematic view showing the synthesis of functionalized metal nanoparticles according to an embodiment of the present invention.

FIG. 2 is a schematic view of a carbon nanostructure in which functionalized metal nanoparticles are deposited through π-π bonds according to an exemplary embodiment of the present invention.

3 is a TEM image of carbon nanotubes on which silver nanoparticles prepared according to an exemplary embodiment of the present invention are deposited.

FIG. 4 is a view schematically showing the shape of carbon nanostructures and conductive particles on which metal nanoparticles are deposited in a conductive paste according to an exemplary embodiment of the present invention.

5 is a graph showing the resistivity characteristics of the conductive paste according to the change in the weight ratio of the carbon nanotubes on which Ag nanoparticles are deposited in the test example of the present invention.

Claims (13)

With benzyl mercaptan, benzenethiol, triphenylmethanethiol, bromobenzyl mercaptan, aminothiophenol and 2-phenylethanethiol Carbon nanostructures on which metal nanoparticles functionalized with a phenyl ring and a thiol group selected from the group consisting of: are deposited; Conductive particles; And bookbinder Conductive paste comprising a. delete The method of claim 1, The metal nanoparticle is a conductive paste, characterized in that the nanoparticles of a metal selected from the group consisting of Au, Pt, Ag, Cu, Ni and Ru. The method of claim 1, The carbon nanostructure is conductive paste, characterized in that selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes and graphene. The method of claim 1, The conductive paste, characterized in that the carbon nanostructure on which the metal nanoparticles functionalized with the phenyl ring and the thiol group are deposited comprises 15 wt% to 85 wt% of the deposited metal nanoparticles. The method of claim 1, The conductive particles are conductive paste, characterized in that the powder of the metal selected from the group consisting of Au, Pt, Ag, Cu, Ni and Ru. The method of claim 1, The binder is an electrically conductive paste, characterized in that it comprises an epoxy resin. The method of claim 1, 0.5 to 15 parts by weight of the carbon nanostructures on which the metal nanoparticles are deposited; 50 to 90 parts by weight of the conductive particles; And 1 to 49.5 parts by weight of the binder A conductive paste comprising a. The method of claim 8, A conductive paste comprising the carbon nanostructure on which the metal nanoparticles are deposited at 0.5 to 3 parts by weight. The method of claim 1, The conductive paste has a specific resistance of 5 X 10 ^-4 to 2 X 10 ^-6 Pa.cm after curing. Preparing a colloid of functionalized metal nanoparticles by mixing a compound having a phenyl ring and a thiol group with a metal solution; Preparing a carbon nanostructure on which the metal nanoparticles are deposited by mixing the colloid of the functionalized metal nanoparticles with a solution in which the carbon nanostructures are dispersed; And Mixing conductive particles and a binder to the carbon nanostructures on which the metal nanoparticles are deposited. Method for producing a conductive paste comprising a. The method of claim 11, Compounds having a phenyl ring and a thiol group include benzyl mercaptan, benzenethiol, triphenylmethanethiol, bromobenzyl mercaptan, aminothiophenol, and 2- Method for producing a conductive paste, characterized in that selected from the group consisting of phenylethane thiol (2-phenylethanethiol). The method of claim 11, In the manufacturing of the carbon nanostructures on which the metal nanoparticles are deposited, A method of producing a conductive paste, characterized in that the colloid of the functionalized metal nanoparticles is sonicated when mixed with a solution in which carbon nanostructures are dispersed.

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