Stabilizing contact resistance of conductive adhesives on Sn surface by novel corrosion inhibitors

Electrically conductive adhesives (ECAs) have been proposed as one of the major alternatives for tin/lead solders in electronic packaging. However, some critical limitations of this technology, such as lower electrical conductivity and unstable contact resistance during elevated temperature and humidity aging, have slowed its potentially wide applications in electronics industry. In this study, novel organic corrosion inhibitors were discovered and introduced into a typical ECA formulation. With the incorporation of small amount of the additives, much lower bulk resistivity of ECAs and significantly stabilized contact resistance on Sn surfaces could be achieved. Contact angle and FTIR characterization indicated the affinity and interaction between the corrosion inhibitors and the metal surfaces. Therefore, a barrier passivation layer could form on Sn surfaces for ECA with the effective corrosion inhibitors. X-ray diffraction analyses confirmed that such a passivation layer could protect the Sn surface and prevent oxidation and corrosion under the elevated temperature and humidity environment.