Reliability of paste based transient liquid phase sintered interconnects

In this paper we present Transient Liquid Phase Sintering (TLPS) as a technology that shows the potential for reliable interconnection in electronic systems under extreme temperature conditions. Ni-Sn and Ni-Cu-Sn TLPS sinter pastes have been developed that enable the formation of joints with a microstructure that is characterized by pure metallic particles (Ni, Cu) embedded in a matrix of (Ni, Cu)-Sn intermetallics. They can be processed at low temperatures, but possess high melting temperatures upon process completion. No application of vacuum or reducing atmosphere is required during processing. Good wetting capabilities are demonstrated for Cu-, Ni-, and Ag-metallizations and low levels of voiding are achieved. Depending on paste composition, the joints can possess high melting temperatures of above 600 C. Superior drop test reliability of Ni-Sn sinter joints compared to those formed with Sn3.5Ag solder is demonstrated.