RU2522887C2 - Method of conductive layer forming on carbon nanotube base - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention refers to electrical engineering, particularly to methods of conductive layer formation used in wide range of technics, including electronics or electrical equipment, and can be applied to form conductive links in microcircuits. Method of conductive layer formation on carbon nanotube base involves application of suspension of carbon nanotubes and carboxymethyl cellulose in water onto substrate, with the following component ratio, wt %: carboxymethyl cellulose 1-10, carbon nanotubes 1-10, drying at 20 to 150°C, pyrolysis at temperature over 250°C.

EFFECT: enhanced electric conductivity of layers formed.

4 cl, 1 tbl

Description

The claimed invention relates to the field of electrical engineering, in particular to methods for creating electrically conductive layers used in wide areas of technology, including electronics, and can be used, for example, to create conductive compounds in microcircuits.

Currently, the technical solution “Nanostructured composites” is known according to the American application for invention US 2010/0068461 A1 (IPC В29С 39/02; В32В 3/10 published March 18, 2010) for producing a nanostructured composite conductive material using arrays of carbon nanotubes (CNTs) ) and a polymer matrix. As the polymer matrix, materials from the following groups are used: acrylates, acrylic acids, polyacrylic esters, polyacrylamides, polyacrylonitriles, chlorinated polymers, fluorine-containing polymers, styrene, polyurethane, rubber polymers, synthetic rubber polymers, vinyl chloride-acrylate polymers, copolymers and their combinations. The disadvantage of this method of obtaining a nanostructured electrically conductive material is the multi-stage process of forming an electrically conductive material, the use of structured arrays of CNTs that limit the maximum geometric dimensions of the electrically conductive material and the low conductivity of the obtained product.

The closest set of essential features (prototype) of the invention is the method described in the US application for the invention "Carbon nanotube-conductive polymer composites, methods of making and articles made therefrom" US 2012/0058255 A1 (IPC B05D 5/12; H01B 1 / 02; H01B 1/04; H01B 1/12 published March 8, 2012). In the present invention, a conductive polymer with the addition of functionalized carbon nanotubes is used to create a composite electrically conductive material. Moreover, the functionalization of CNTs is carried out by various groups, including: —COOH, —OH, and —COOAg groups. Signs consistent with the claimed invention are the application of a suspension containing carbon nanotubes to a substrate, drying at a temperature of up to 150 ° C.

Obtaining the required technical result is hindered by the use of only functionalized CNTs, additional processing of CNTs to form functional groups on the CNT surface, the use of electrically conductive polymers to increase the electrical conductivity of the resulting material, which reduces the amount of organic compounds used as a polymer matrix and limits the use of the obtained electrically conductive material.

An object of the present invention is to provide a method for forming an electrically conductive layer based on carbon nanotubes.

The technical result consists in expanding the functionality of the method of forming an electrically conductive layer based on carbon nanotubes, in using CNTs without additional chemical treatments after synthesis, in increasing the electrical conductivity of the formed layers.

To achieve the above technical result, a method of forming an electrically conductive layer based on carbon nanotubes involves applying a suspension of carbon nanotubes and a solution of carboxymethyl cellulose in water to a substrate in the following ratio, wt.%: Carboxymethyl cellulose 1-10 and carbon nanotubes 1-10, drying at temperature from 20 to 150 ° C, pyrolysis at a temperature of 250 ° C-300 ° C.

This method differs from the prototype in that the suspension contains a solution of carboxymethyl cellulose in water in the following ratio of components, wt.%: Carboxymethyl cellulose 1-10 and carbon nanotubes 1-10, drying is carried out at a temperature of from 20 to 150 ° C, as a final stage Carboxymethyl cellulose is pyrolyzed at temperatures above 250 ° C.

The introduction of this operation allows the formation of electrically conductive layers based on carbon nanotubes with sufficient reproducibility of the results. By drying, water is removed from the suspension. Carrying out the pyrolysis of carboxymethyl cellulose can increase the electrical conductivity of the layers due to the decomposition of the organic compound. When implementing the inventive method, the structure of the electrically conductive layer is obtained, which is different from the structure obtained by the method of the prototype.

In particular cases of the invention, metal, ceramics, glass, silicon, silicon oxide, silicon nitride or their compositions are used as a substrate.

In particular cases of the invention, the suspension is applied to a substrate by printing or silk-screen printing.

In particular cases of the invention, the drying is carried out by thermal and / or vacuum method.

The combination of features characterizing the invention allows the formation of electrically conductive layers based on carbon nanotubes using CNTs without functional groups on the surface of CNTs and without the use of conductive polymers.

The invention is illustrated by a table comparing the characteristics of the achieved technical result with the result presented in the prototype.

The method of forming an electrically conductive layer based on carbon nanotubes includes the steps of: applying a suspension of carbon nanotubes and a solution of carboxymethyl cellulose in water to a substrate, in the following ratio, wt.%: Carboxymethyl cellulose 1-10 and carbon nanotubes 1-10, drying at a temperature of 20 up to 150 ° C, pyrolysis at temperatures above 250 ° C.

Example 1

To form an electrically conductive layer based on carbon nanotubes, a solution of carboxymethyl cellulose (CMC) in water is formed by adding 6 wt.% CMC to water and mixing the components mechanically using a magnetic stirrer for 60 min, adding 5 wt.% CNTs to the solution and mixing the suspension using ultrasound for 90 min, applying the suspension to the substrate by silk-screen printing, removing solvent (water) from the suspension at a temperature of 90 ° C at a pressure of 10 kPa for 20 min, pyrolyzing and the organic compound at a temperature of 300 ° C at a pressure of 10 kPa for 25 minutes.

The conductivity of the obtained CNT-based conductive layer is 50,000 S / m. The table shows a comparison of the achieved result with the prototype. The obtained result shows that the pyrolysis of the organic compound can increase the conductivity of the material without functionalizing CNTs and using conductive polymers.

Example 2

To form an electrically conductive layer based on carbon nanotubes, a CMC solution in water is formed by adding 6 wt.% CMC to water and mixing the components mechanically using a magnetic stirrer for 60 min, adding 5 wt.% CNTs to the solution and mixing the suspension using ultrasonic exposure for 90 minutes, applying the suspension to the substrate by silk-screen printing, removing solvent (water) from the suspension at a temperature of 90 ° C at a pressure of 10 kPa for 20 minutes, then pyrolyzing the organic compound eniya at a temperature of 200 ° C at a pressure of 10 kPa for 25 minutes.

The conductivity of the obtained CNT-based conductive layer is 1000 S / m. The result shows that at a temperature of 200 ° C, which is 50 ° C less than the temperature of the onset of CMC pyrolysis, the decomposition of the organic compound does not occur and the conductivity of the material remains low.

Table Comparative characteristics of the achieved technical result with the result presented in the prototype. Properties of nanomaterial Invention Prototype The concentration of carbon nanotubes, wt.% 5 5 Electrical conductivity, cm / m 50,000 40,000 The form Volumetric, any configuration Filamentous fiber

Claims (4)

1. A method of forming an electrically conductive layer based on carbon nanotubes, comprising applying to a substrate a suspension containing carbon nanotubes and a solution of carboxymethyl cellulose in water in the following ratio of components, wt.%: Carboxymethyl cellulose 1-10 and carbon nanotubes 1-10, drying at a temperature of 20 up to 150 ° C, pyrolysis at temperatures above 250 ° C. 2. The method according to claim 1, characterized in that the substrate is metal, ceramic, glass, silicon, silicon oxide, silicon nitride, or a composition thereof. 3. The method according to claim 1, characterized in that the suspension is applied to the substrate by printing or silk screen printing. 4. The method according to claim 1, characterized in that the drying is carried out by thermal and / or vacuum method.