STUDIES ON ELECTRICALLY CONDUCTIVE ADHESIVES

Abstract

Electrically conductive adhesives made up of silver nano-particles as the main filler and polyaniline co-filler were synthesised and then characterized for their electrical and mechanical properties. Silver is a metallic substance which has the highest electrical conductivity among metals and also it has the ability to conduct electricity in its metallic and oxide form. Also, polyaniline (PANI) is a conducting polymer which possesses moderate conductivity that lies in between the silver and epoxy resin. Incorporation of polyaniline and silver in epoxy facilitates the electrical conduction. Polyaniline (PANI) also prevents the aggregation of silver filler particles caused by the localization of charge carriers. Polyaniline (PANI) enabled the bridging effect in which it enhanced the tunnelling of electrons above the silver-nano particles. Investigations on the silver-polyaniline reinforcements based epoxy as a promising alternative to lead/tin solders was exhibited in the project due to enhanced tuning of the mechanical and electrical properties of silver-polyaniline epoxy composite and silver-epoxy system in cured state. A comparison of the three composites, silver-polyaniline-epoxy, polyaniline-epoxy and silver-epoxy and also different polyaniline concentrations in the conductive adhesives was done and silver-polyaniline epoxy showed the highest conductivity (1.184 S/cm) and the composite with 10% polyaniline concentration showed the highest conductivity (10.62×10-6 S/cm) among all concentrations studied in the present report. Silver-polyaniline-epoxy composite showed the highest shear strength of 28 MPa at 1% polyaniline. The motivation behind combining the two reinforcements was to eliminate the use of lead tin solders. In this project report, the optical, mechanical, morphological and electrical properties of ICAs have been reported.