Monolayer-protected silver nano-particle-based anisotropic conductive adhesives: Enhancement of electrical and thermal properties

Two types of self-assembled monolayers (SAMs), dicarboxylic acid and dithiol, were used to treat the silver nanoparticles. Thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), and contact angle results indicated that the SAMs were well coated on the silver nanoparticles and thermally stable below 150 degrees C. By introducing the monolayer-coated silver nanoparticles into the anisotropic conductive adhesives (ACAs), the electrical properties and thermal conductivity of ACAs were significantly improved. The joint resistance of the ACA decreased from 10(-3) Ohm to 10(-5) Ohm with SAMs-coated silver fillers, and the current carrying capability of ACAs was also obviously improved. The improved electrical properties are due to the stronger bonding between nanofillers and the SAM coating materials; consequently, this improved the ACA interfacial properties. The enhanced interfacial properties with the SAM-protected nanofillers also attributed to the improved thermal conductivity of ACAs.