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 (1).
Despite its importance, few studies have been made on the low temperature oxidation of the
copper-base alloys (2), 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.