Evolution of microstructure and residual stress for a lead-frame Cu-2.13Fe-0.026 P (wt%) alloy

The evolution of the dislocation density, precipitates, texture, and residual stress in lead-frame Cu-2.13Fe-0.026 P (wt.%) alloys were studied. All samples showed residual compressive stress. Moreover, the dislocation density and residual stress of the rolled sample are higher than those of the annealed sample. After annealing, the sample is mainly composed of restored grains, and the dislocation density not generated an order of magnitude decrease. This trend may be the reason why the residual stress still exists in the sample after annealing. In addition, the presence of pits around Fe3P particles may contribute to the generation of the residual stress. More importantly, the texture type of each sample is mainly Brass (011)<211>, S (123)<634> or Copper (112)<111>, and the recrystallized Cube (001)<100> texture is rarely found. Finally, the structural energy density (Ev) of different textures is calculated. It was found that the Ev of the Copper (112)<111> texture affects the variation of its volume fraction, thereby controlling the evolution of the residual stress.