CN101003909A - Electrochemical combined deposition method for preparing structure of composite membrane of Nano carbon tube - metal - Google Patents

Abstract

The invention discloses a method for preparing a carbon nanotube-metal composite film structure by electrochemical combined deposition, which belongs to the technical field of nanometer materials. In the present invention, the purified, sheared, and dispersed carbon nanotubes are formulated into a stable and dispersed carbon nanotube electrophoresis solution, which contains carbon nanotubes, an electrophoretic dispersant, and a charging assistant salt for charge modification; A voltage is applied to the electrodes, and a uniform carbon tube film is first deposited on the substrate by electrophoresis, and then the above film is placed in the electroplating solution, and a metal conductive film is formed in the microstructure between the carbon tubes by electrochemical methods. The invention reduces the contact resistance between the metal and the carbon tube, exerts the good electric conduction and heat conduction performance of the carbon tube, and improves the combination ability of the carbon tube and the conductive substrate. The invention has better compatibility with microfabrication, and has the characteristics of simple equipment process, large-area preparation, strong operation controllability, high efficiency and low cost, and the like.

Description

Method for preparing carbon nanotube-metal composite film structure by electrochemical combined deposition

technical field

The invention relates to a preparation method in the technical field of nanomaterials, in particular to a method for preparing a carbon nanotube-metal composite film structure by electrochemical combined deposition.

Background technique

Carbon nanotubes have excellent electrical properties, especially in enhancing electrical and thermal conductivity. Therefore, they have important and extensive application prospects in the application of high-performance electronic devices. However, since carbon nanotubes are quasi-one-dimensional nanostructures, they have high surface energy and are not easy to disperse. Special preparation methods are required to combine them with existing device materials and processes, so as to realize Apply effectively. In the application of many electronic devices, carbon nanotubes need to be formed into a certain thin film or microstructure, but no effective and reliable preparation technology has been formed yet, so research in this area has become a focus of scholars from various countries.

At present, the methods for forming carbon nanotube thin films are mainly divided into two categories: direct growth method and film formation method after treatment. The former mainly adopts the chemical vapor deposition (CVD) preparation method, which has disadvantages such as expensive manufacturing equipment, high growth temperature, and inability to obtain high-quality carbon tubes with a single structure. After treatment, the film-forming methods are mainly drop coating, spin (spray) coating, dipping, self-assembly, silk screen printing, electrophoresis, composite electroplating and other methods. The characteristics of these methods are that the separated carbon tubes are purified, sheared, dispersed, etc. treatment, and then add other media materials, mix to form a uniform carbon tube solution, and then select the above method to form a carbon nanotube film structure. The post-treatment deposition method avoids the problem of high temperature growth and solves the problem of carbon tube structure selection. However, except for composite electroplating, carbon tubes obtained by other methods are bonded to the substrate by electrostatic adsorption, so the bonding force between the film and the substrate is relatively weak. Difference. Due to the use of the electrochemical reaction deposition mechanism, the bonding force between the carbon tubes deposited by composite electroplating and the surrounding metal matrix and substrate has been improved, but the dispersion of carbon tubes in the plating solution is difficult, resulting in the distribution of carbon tubes in the composite film. Concentration is not easy to control and other problems. Electrophoretic deposition is a widely used carbon tube film-forming method at present, and it has been reported in domestic and foreign patents. Although this technology better solves the problems of carbon tube dispersion and concentration control, it still has certain problems in the binding force of the film because it still uses the principle of electrostatic adsorption.

After searching the literature of the prior art, it was found that the Chinese patent application number is 200510053855.1, and in the invention patent named "Method for Improving the Uniformity of Electron Source of Carbon Nanotubes Fabricated by Electrophoretic Deposition", a method for improving the electrical conductivity of thin films is proposed Specifically, metal salts such as indium chloride or indium nitrate are added to the electrophoretic solution, and the film is sintered at a temperature of 400°C after deposition, so that indium hydroxide is converted into indium oxide when it is formed during electrophoretic deposition, because indium oxide has Conductivity and form around the carbon tubes, which can play a role in fixing the carbon tubes and increasing the conductivity. In this technology, the bonding force and conductivity of the film are solved by high-temperature sintering, which obviously introduces the problems of high temperature and substrate limitations.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and propose a method for preparing a carbon nanotube film structure by electrochemical combined deposition. The invention combines the advantages of electrophoresis and electroplating deposition, effectively reduces the contact resistance between metal and carbon tubes, makes full use of the good electrical conductivity and thermal conductivity of carbon tubes, and improves the bonding ability of carbon tube films and conductive substrates.

The present invention is achieved through the following technical solutions. The present invention formulates the purified, sheared and dispersed carbon nanotubes into a stable and dispersed carbon nanotube electrophoresis solution. The electrophoresis solution contains carbon nanotubes, an electrophoretic dispersant and Charge-assisted salts for charge modification. A voltage is applied to the electrodes, and a uniform carbon tube film is first deposited on the substrate by electrophoresis, and then the above film is placed in the electroplating solution, and a metal conductive film is formed in the microstructure between the carbon tubes by an electrochemical method. The invention can control the carbon tube concentration in the carbon nanotube-metal composite film by adjusting the concentration of the carbon tube in the electrophoresis, the electric field strength and the deposition time. By adjusting the current density and deposition time during electroplating, the thickness of the metal conductive film can be controlled. By adjusting the number of combined electrophoresis-electroplating depositions, the total carbon nanotube-metal composite film thickness can be adjusted.

The carbon nanotubes used in the present invention may be multi-walled or single-walled.

The electrochemical method in the present invention is an electroplating or electroless plating method, and the deposited metals are Ni, Cu, Ag, Au, Zn, Sn, FeNi and the like.

The electrophoresis method and the electrochemical method in the present invention, the combined deposition of these two methods can be a single deposition or multiple repeated depositions.

The carbon tube film structure deposited by the electrophoresis method in the present invention can be a continuous film or a pattern film structure. The preferred method of electrophoresis method for depositing graphic film structure is: select acetone as the electrophoretic dispersion liquid, and select polyimide or negative photoresist as the graphic mask material.

The basic parameters of the deposition of the electrophoresis method of the present invention are: the weight percentage concentration of carbon nanotubes in the electrophoresis solution is: 0.05-1%, the electrophoresis dispersant is an alcohol or ketone solution, and the auxiliary salt used for charging can be magnesium nitrate, nitric acid Aluminum or magnesium chloride, etc., preferably magnesium nitrate, the weight percentage concentration is 0.1-0.5%, the electrode cathode is a deposition substrate, and the anode is a stainless steel sheet. During electrophoretic deposition, an electric field intensity of 5-20 V/cm is applied for 2-10 minutes.

In the electrochemical method of the present invention, the electroplating solution can use a conventional basic metal plating solution, and the electroplating current density during deposition is 0.2A-2A/dm ² , and the time is 2-5 minutes.

The present invention combines the advantages of electrophoresis and electroplating deposition to make up for the shortcomings of their respective methods. Electrophoresis and electroplating deposition are carried out alternately on the substrate, and a carbon tube film with uniform dispersion and controllable concentration is first formed on the substrate through electrophoretic deposition. , followed by electroplating deposition, using the electrochemical reaction during electroplating to establish a metal conductive connection in the microstructure between the carbon tubes, so that the carbon tubes are uniformly and densely embedded in the conductive metal film. The carbon tube thin film deposited by the invention has outstanding characteristics such as good dispersibility, easy adjustment of carbon tube concentration, flexible thickness control, good adhesion and enhanced conductivity. The technology of the present invention has good compatibility with microfabrication technology, can conveniently prepare various micrographic structures, has practical characteristics such as simple equipment process, strong controllability, large-area preparation, high efficiency and low cost, and is suitable for high-performance Fabrication and application of electronic devices.

Detailed ways

The embodiments of the present invention are described in detail below: the present embodiment is implemented under the premise of the technical solution of the present invention, and detailed implementation and specific operation process are provided, but the protection scope of the present invention is not limited to the following implementation example.

Example 1

1. Get diameter 40-60nm, length is 5-10um, 10mg of multi-walled carbon nanotubes after purification, shearing, dispersion treatment, magnesium nitrate 5mg, dehydrated alcohol 1266ml are mixed with carbon tube electrophoresis solution, then this The solution was ultrasonicated for 60 minutes to form a well-dispersed suspension solution.

2. Use a conductive metal sheet or an insulating substrate deposited with a conductive metal film as the deposition base material and the cathode during electrophoretic deposition, and use a stainless steel sheet as the electrophoretic anode. Put the two electrodes into a container filled with electrophoretic solution, the distance between the two electrodes is 4cm, apply a DC voltage of 20V at both ends of the electrodes, and the electrophoresis time is 10 minutes.

3. After taking out the electrophoresis sample and drying it, put it into the acidic copper electroplating solution, still use the deposition substrate as the cathode, and the phosphor copper plate as the anode, and apply the electroplating current density of 2A/dm ² for 2 minutes.

After the above operations, a uniform carbon tube/copper composite film can be obtained. Observation by field emission scanning electron microscope shows that the density of carbon tubes in the film is high, the distribution of carbon tubes in the deposition area is uniform, and they are interconnected to form a network structure, there is no obvious hole between carbon tubes and metal. Carbon tube content reaches 80%.

Example 2

1. Take 5 mg of single-walled carbon nanotubes with a diameter of 1-2 nm and a length of 5-10 um after purification, shearing, and dispersion treatment, 3 mg of magnesium nitrate, and 1266 ml of absolute ethanol to prepare a carbon tube electrophoresis solution, and then the solution Sonicate for 60 minutes to form a well-dispersed suspension solution.

2. Using a silicon wafer as the base material, sputtering and depositing Ti on the surface as a metal conductive layer, and forming a Ti pattern structure by photolithography and etching.

3. The above-mentioned micro-pattern substrate is used as the electrophoretic cathode, and the stainless steel sheet is used as the anode, and the two electrodes are placed in a container filled with electrophoretic liquid. The distance between the two electrodes is 4cm, and a DC voltage of 40V is applied at both ends of the electrodes. The electrophoresis time is 6 minutes.

4. After the electrophoresis sample was taken out and dried, it was put into the Watts nickel electroplating solution, the deposition base material was used as the cathode, the nickel plate was used as the anode, and the electroplating current density was 1A/dm ² for 3 minutes.

5. After repeating 3 and 4 twice, a micrographic structure of carbon tubes and Ni composites can be obtained. Field emission scanning electron microscope observation shows that carbon tubes are evenly embedded in the Ni layer, and the content of carbon tubes in the film is analyzed by X-ray energy dispersive spectroscopy. up to 50%.

Example 3

1. Take 5mg of multi-walled carbon nanotubes with a diameter of 40-60nm and a length of 5-10um after purification, shearing and dispersion treatment, 5mg of magnesium nitrate, and 1250ml of acetone to prepare a carbon tube electrophoresis solution, and then sonicate the solution After 60 minutes, a well-dispersed suspension solution was formed.

2. Glass flakes are used as the deposition base material, and Cu/Ti is deposited on the surface as the metal conductive layer by sputtering. Spin-coat polyimide on the deposition substrate as a pattern mask material, and form a microstructure mask pattern after photolithography and development.

3. The above-mentioned micro-pattern substrate is used as the electrophoretic cathode, and the stainless steel sheet is used as the anode, and the two electrodes are placed in a container filled with electrophoretic liquid. The distance between the two electrodes is 4 cm, and a DC voltage of 80V is applied to both ends of the electrodes. The electrophoresis time is 3 minutes.

4. After taking out the electrophoresis sample and drying it, put it into the Watts nickel electroplating solution, still use the deposition base material as the cathode, and the nickel plate as the anode, and apply the electroplating current density of 0.2A/dm2 for 5 minutes.

5. After repeating 3 and 4 three times, the carbon tube/Ni micropattern structure can be obtained. Observation by the field emission scanning electron microscope shows that the surface of the micropattern is covered with uniform carbon tubes, some carbon tubes are embedded in the Ni layer, and some carbon tubes are exposed to the micro The surface of the structure is analyzed by an energy scattering spectrometer, and the content of carbon tubes in the film is 70%. This structure is suitable for field emission and ionization electrode structure applications.

Claims (10)

1. an electrochemical combined deposition prepares the method for structure of composite membrane of Nano carbon tube-metal, it is characterized in that: the carbon nanotube after purified, shearing, the dispersion treatment is mixed with the carbon nano-tube electrophoretic solution of stable dispersion, contains carbon nanotube, electrophoresis dispersion agent in the electrophoresis solution and be used for the charged auxiliary salt that electric charge is modified; On electrode, apply voltage, on substrate, deposit layer of even carbon pipe film earlier, then above-mentioned film is put into electroplate liquid, by forming metal conductive film in the microstructure of electrochemical method between the carbon pipe by electrophoresis method.

2. electrochemical combined deposition as claimed in claim 1 prepares the method for carbon nanotube membrane structure, it is characterized in that: described carbon nanotube is single wall or multi-walled carbon nano-tubes.

3. electrochemical combined deposition as claimed in claim 1 prepares the method for carbon nanotube membrane structure, it is characterized in that: described electrophoresis method and electrochemical method, both combined depositions are single deposition or repeated deposition repeatedly.

4. prepare the method for carbon nanotube membrane structure as claim 1 or 3 described electrochemical combined depositions, it is characterized in that: described electrochemical method is to electroplate or chemical plating method, and sedimentary metal is a kind of among Ni, Cu, Ag, Au, Zn, Sn, the FeNi.

5. electrochemical combined deposition as claimed in claim 1 prepares the method for carbon nanotube membrane structure, it is characterized in that: described electrophoresis method, its sedimentary basic parameter is: the carbon nanotube weight percent concentration in the electrophoresis liquid is: 0.05-1%, being used for charged auxiliary salt is magnesium nitrate or magnesium chloride, and weight percent concentration is 0.1-0.5%; Electrophoresis applies strength of electric field 5-20V/cm, and the time is 3-10 minute.

6. electrochemical combined deposition as claimed in claim 5 prepares the method for carbon nanotube membrane structure, it is characterized in that: described to be used for charged auxiliary salt be magnesium nitrate.

7. electrochemical combined deposition as claimed in claim 1 prepares the method for carbon nanotube membrane structure, it is characterized in that: described electrophoresis dispersion agent is alcohols or ketone solution; Described electrode, its negative electrode are deposition substrate, and anode is a stainless steel sheet.

8. electrochemical combined deposition as claimed in claim 1 prepares the method for carbon nanotube membrane structure, it is characterized in that: described electrochemical method, its sedimentary processing parameter is: electroplate liquid uses conventional metal plating liquid, and the electroplating current density during deposition is 0.2A-2A/dm ², the time is 2-5 minute.

9. electrochemical combined deposition as claimed in claim 1 prepares the method for carbon nanotube membrane structure, it is characterized in that: described by the sedimentary carbon pipe of electrophoresis method film, and be continuous film or graphic films structure.

10. electrochemical combined deposition as claimed in claim 9 prepares the method for carbon nanotube membrane structure, it is characterized in that: described electrophoresis method deposition pattern membrane structure, be specially: select for use acetone as electrophoresis dispersion, the figure mask material is selected polyimide or negative photoresist for use.