Development of conductive adhesives with novel corrosion inhibitors for stabilizing contact resistance on non-noble lead-free finishes

As a potential alternative to lead-bearing soldering technology, conductive adhesive technology has attracted more and more attention of the electronics industry. This new technology can offer numerous advantages over traditional soldering technology. 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, innovative organic corrosion inhibitors were discovered and introduced into a typical ECA formulation. With the incorporation of small amount of the additives, obviously 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. A barrier passivation layer could form on Sn surfaces during the processing 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.