Corrosion Studies on Gold-Plated Electrical Contacts

Long-term reliability of electrical connectors are influenced by the type of plating and plating process. In this paper, the authors look for a viable alternative to 400-nm ENIG + EG (electroless Ni, immersion Au + electroless Au) for microelectronic package substrates. In alignment with historical work, the authors choose NiPdAu (electroless Ni, electroless Pd, immersion Au) as the alternative plating with about 85% reduction in Au thickness. The investigation was mainly on contact resistance degradation due to corrosion between the package substrate and socket contacts. Corrosion studies were based on experiments leading to gold wearout and exposure to corrosive test environment, including temperature, humidity, and mixed flowing gas. The scope of investigation was limited to connectors that are infrequently mated once they are shipped to an end user from the assembly factory.