Electrical, structural and processing properties of electrically conductive adhesives

There is growing interest in the potential of electrically conductive metal-loaded polymer adhesives. Eight commercial electrically conductive adhesive pastes for solder replacement in surface mount technology (SMT) and other microelectronic applications were selected for study, including both thermosetting and thermoplastic examples. All were silver based, except for one nickel-polymer composite. The properties on which this work was focused were the microstructure and electrical characteristics, with the specific purpose of determining the conduction mechanisms. The electrical measurements established that the primary source of electrical resistance is in the silver particles, with negligible contact effects between them. Differential scanning calorimetry results indicated that drifts in the electrical properties are not attributable to incomplete cures. Electrical measurements on simplified structures prepared in the laboratory are also reported