Cu-base leadframes, together with the silicon chip, the gold wire and the epoxy molding compound, are one of the most important materials used in the plastic packages. Cu-base alloys as leadframe materials have advantages such as high electrical/thermal conductivity and low cost compared to a Fe-base alloy, Alloy 42 (Fe-42wt%Ni). However, Cu-base leadframe alloys are very susceptible to thermal oxidation when exposed to elevated temperatures in electronic packaging process, typically ranging from 150°C to 300°C for various time depending upon the type of materials used. When the leadframe surface is covered with a copper oxide film, poor adhesion of leadframe to the epoxy molding compound (EMC) has generally been reported, resulting in the Cu/EMC interface delamination, which in turn significantly decreases moisture resistance of the plastic package.
Despite its importance, few studies have been made on the low temperature oxidation of the copper-base alloys, particularly Cu-base leadframe alloys. Therefore we investigated the growth kinetics and the composition of oxide films which are formed on a commercial leadframe alloy at 150°C to 300°C in air.