Chlorine and sulfur effects on silver bonding wire reliability

Currently, wire bonding still plays an important role in microelectronic packaging, making electrical connections between chips and leadframe or substrate. Silver (Ag) bonding wire is attracting more and more attention due to its advantages, such as the lower material price compared to gold wire, excellent electrical and thermal conductivity. The IMCs at the Ag and aluminum (Al) pad interface have an essential impact on the reliability. Ag wire are generally applied in consumer products as a reliable low-cost alternative to gold wire. In automotive applications, the materials are often exposed to strict conditions, such as moisture and chlorine (Cl) environment [4]. Therefore, it is necessary to make more effect on the Al wire bond reliability.This paper discusses the Cl effect on the Ag wire bond. Different levels of Cl were purposely added into the epoxy molding compound (EMC). To compare the Cl effect on Ag wire bond reliability, accelerated reliability tests biased highly accelerated stress test (bHAST), pressure cooker test (PCT), and temperature cycle test (TCT) were performed. It is found that Cl served as a catalyst in IMC corrosion under bHAST and PCT tests. However, S did not cause failure in Ag-Al wire bond.