Effect of Zn-addition and structural transformation on the creep behaviour of Pb-10 wt.\% Sn alloy

Pb-10 wt.\% Sri alloy is one of the materials considered for the spheres used in Ball Grid Array (BGA) of the most popular packaging technologies. The tensile creep behaviour of Pb- 10 wt.\% Sn and Pb- 10 wt.\% Sn-1.5 wt.\% Zn alloys was investigated at different working temperatures ranging front 373 to 443 K and under different constant applied stresses. Stress exponent n and activation energy Q(c) were determined to clarify the deformation mechanism. X-ray analysis and differential thermal analysis (DTA) were studied to evaluate the structural changes during trans formations. Attention has been paid to the role of zinc on the creep behaviour of Pb-10 wt.\% Sri, the influence of Zn on the melting temperature (T) and apparent activation energy of creep. Microstructure examination of the deformed samples below and above the transition temperatures was performed. (C) 2004 Elsevier B.V. All rights reserved.