Preparation Of Conductive Ink Used In Soft Substrate Circuit Board And Printability Study Of The Ink

Micro and nano conductive copper powder, which is cheap and thermal conductivity, has become more and more widely used in electronic industry. The conductive ink, which was prepared by micro and nano copper powder, can replace the electrochemical corrosion method to make the circuit directly on the substrate and this method can decrease costs.But at the same time the copper powder has weakness such as easily oxidized when it is dried and the micro and nano copper powder also easily gather around. It is very important to modify the surface of micro and nano conductive copper powder.In this thesis, micron copper powder and nano copper powder were modified by coating conductive polymer polyaniline on the surface respectively. Firstly, two step continuous inverse microemulsion synthesis was used to prepare coreshell structure of polyaniline/copper composite nanoparticles. Secondly, micron copper powder coated with polyanilinethe was prepared by situ polymerization solution method. Then the modified copper powder used as a kind of conductive filler to design conductive ink formulation. Finally, a kind of conductive ink was prepared and it was suitable for printing on the surface of the soft base of polyimide(PI) and its printing eligibility was also studied.In order to prepare nano copper power coated with PI, the stability of inverse microemulsion was required to be investigated. This paper investigated the influence of inverse microemulsion components on the stability of the microemulsion system, and mapped the pseudo ternary phase diagram. According to the pseudo ternary phase diagram we could analysis the formation of the stable microemulsion. When the mass fraction of n-heptane was 22.7% to 27.2%, sodium dodecyl sulfate and water mass fraction was 34.0%- 40.9%, the mass fraction of isoamyl alcohol was 31.9%-43.3%, we could form a stable W/O reverse microemulsion. In this inverse microemulsion system we could get modified nano copper composite particles which use polyaniline enveloped by nanometer copper as nuclear. The product were analysed in different wayes: Fourier infrared spectrum(FTIR), EDS energy spectrum analysis, transmission electron microscopy(TEM) observation. The results showed that the diameter of polyaniline/copper composite particle was 30 nm by continuous two-step inverse microemulsion reation on ice, and the structure was clear diffuse multi-core-type core-shell. Using Solution polymerization in situ to modification micron copper powder, when the dosage of copper powder was1 g, aniline hydrochloride was 0.35 ml, H2O2 was 0.45 ml, we found that copper powder surface could form a dense homogeneous polyaniline coating layer. By study of conductive ink, we found that when the dosage of polyaniline/copper composite nanoparticles was 5.2%, the dosage of modification micron copper powder was 65%, the dosage of resin was 12%, the dosage of curing agent was 1.8%, the dosage of Curing catalyst was 0.8%, the dosage of thinner was 0.8%, conductive ink has good performance.In the experiments, printed the lines on PI and studied the Printability.The result showed that drying process at 120℃ in 10 min, the printing ink layer had excellent comprehensive performance, the volume resistance was 4.4 x 10-3 Ω cm- 3, and the conductive ink fineness, viscosity, adhesion fastness of the preparation had met the standard of GB/T 13217-2008.