Effect of Dispersoids on Softening Behavior in Cu-Fe-P Alloys for Lead Frames

The effect of the amount of dispersoids on softening behavior and recrystallized microstructure of Cu-Fe-P alloy was examined by the extracted residue analysis method. The degrees of contribution of larger particles (larger than 1μm in an average diameter) and smaller ones (less than 0.1μm) to the softening behavior were considered in the quantitative aspect, respectively. It was found that the change of the order of 10-1mass% in the amounts of both particles has a great effect on softening behavior. The difference in the amount of fine particles changes recrystallized grain size distributions at similar hardness. In the specimen with a small amount of fine particles, coarse grains and wide distribution of grain size were observed after annealing. As a result, it was revealed that fine and homogeneous recrystallized microstructure was obtained due to just 0.35mass% of fine partcles, even if the amount of large particles increased.