Chlorine and sulfur effects on copper-aluminum wire bond reliability

Currently, wire bonding is still the dominant interconnection mode in microelectronic packaging. Copper (Cu) bonding wire is widely used due to its advantages, such as low-cost, good electrical conductivity, etc. However, Cu wire bond is susceptible to galvanic corrosion. There are many reports on Cu wire bond failure due to its intermetallic compound (IMC) corrosion with the presence of moisture and corrosive ions. The most common ions found in the Cu wire bond failed sample are Cl and S. This paper discusses the influence of chlorine (Cl) and sulfur (S) effects in the epoxy molding compound on the Cu wire bond. It is found that Cl acted as a catalyst in IMC corrosion under humid environment. Cl also caused wire bond failure in HTS test if the Cl content is high. On the other hand, S is not corrosive ion, and it is not a corrosion catalyst to the Cu wire bond as well.