bHAST, PCT, TCT reliability performance comparison of Cu-Al, PdCu-Al, Ag-Al

Wire bond is the most common inter-connection method used to connect microchips to the terminals of a chip package. Wire bond reliability is vital to the performance of packaging device. It is vital to understand the reliability performance of different wire types under the environment of temperature, moisture and voltage bias. In this study, copper (Cu), palladium coated copper (PdCu) and silver (Ag) wires were boned to aluminum (Al) bond pad. Chlorine (Cl) and sulfur (S) contaminations were purposely introduced to epoxy molding compound (EMC) to accelerate the corrosion process. Reliability tests bHAST (biased highly accelerated stress test), pressure cooker test (PCT) and temperature cycle test (TCT) were conducted. The results showed that bHAST encountered most failures, followed by PCT. Whilst TCT encountered no failure. For the wire type, PdCu-75%Pd coverage showed the best reliability performance among all the legs. For the EMC contamination type, Cl played a significant role on wire bond reliability. Whilst, S did not impact much on wire bond reliability.