The Influence of Temperature on Stress Relaxation in a Chill-Cast, Tin-Lead Solder

Data on the compressive stress relaxation of chill-cast 60/40 tin-lead solders for two loads, 6.89 and 24.8 MN/m2 (mega newtons/ square meter) and for temperatures from 27 to 108°C are presented. For the complete temperature range tested, it is shown that the stress relaxation can be modeled as an Arrhenius reaction-rate process with an activation energy of 0.65 eV This activation energy is in close agreement with solder activation energies inferred from earlier studies of self-diffusion, creep, and creep rupture. This suggests that the stress relaxation is diffusion dominated for the temperature range studied, and that the present results may be extended to other tin-lead solders by using available correlations.