The effect of chemical species in the lead frame materials on the interface microstructure between copper alloys and SnPb solder

Abstract

The effect of chemical species in the leadframe materials on the interface microstructure between copper alloy and SnPb solder was studied by an optical microscope and scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy. The result showed that after aging at 160/spl deg/C for 300h, the intermetallic compound (IMC) at the interface between CuCrZr system, CuNiSi alloys and SnPb solder was formed as Cu/sub 6/Sn/sub 5/, which thickness was about 5/spl sim/10/spl mu/m. The IMC between C19400 alloy and SnPb solder was Cu/sub 6/Sn/sub 5/.,, which thickness was about 60/spl sim/70/spl mu/m. Pb particle and holes were found to be in the IMC, which would be harmful for reliability. The elements of Cr and Zn in CuCrZrZn alloy become rich at the interface between Cu and IMCs, leading to the retardation of the growth of IMCs.