Abstract: Transmission electron microscopy(TEM) observations were carried out for examining the precipitation behavior in a Cu-Sn-Zn-P lead frame material.TEM observations revealed that the precipitate is hexagonal Ni5P2 and the orientation relationship between the Cu matrix and Ni5P2 precipitate is (111)fcc//(0001)hcp,[101]fcc//[1120]hcp,where the suffix fcc denotes the Cu matrix and hcp denotes the hexagonal Ni5P2 precipitate.The Ni5P2 precipitate is ovoidal in shape at the beginning of aging at lower temperature.By prolonging the aging time or increasing the aging temperature,Ni5P2 precipitate grows and shows a rod-like shape.The Ni added Cu based lead frame material has a comparative mechanical properties with that of TAMAC15 which has been developed and used in electrical industry.

Key words: lead frame materials, mechanical properties, atom diffusion,