Conductive adhesive materials for lead solder replacement

Various adhesives were tested for MLCC and integrated circuit (IC) applications as lead solder replacements, mainly from the viewpoint of contact resistance and adhesion strength. Current-voltage and frequency characteristics were also measured. On the whole, the contact resistance depended on the volume resistivity of each adhesive. Different termination and bump materials gave different contact resistance values. Especially, Sn plated terminations tended to give higher contact resistance. The adhesion strengths were also influenced by the kinds of adhesives, electrode, termination and bump materials. Although the Ni filled adhesive, which had good adhesion strength and didn't cause electro-migration, had higher volume resistivity, it gave good I-V characteristics at low current.