Conductive adhesive materials for lead solder replacement

Various adhesives were tested for MLC capacitors and ICs as lead solder replacements from the viewpoints of contact resistance and adhesion strength. I-V 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. In particular, Sn plated terminations tended to give higher contact resistance. The adhesion strength was also influenced by the types of adhesives, and the electrode, termination and bump materials. Although Ni filled adhesive, which had good adhesion strength and did not cause electromigration, had higher volume resistivity, it gave good I-V characteristics at low current.