The as-cast SAC305（Sn3.0 Ag0.5 Cu） lead-free solder was compressed at constant temperature（20～140 ℃） by UTM6202 electronic universal testing machine. According to the experimental data under different working conditions

the flow stress

strain rate and deformation temperature of lead-free solder were fitted

and the parameters of Arrhenius constitutive equation were calculated. The results reveal that the true stress-strain relationship of lead-free solder SAC305 is significantly correlated with temperature and strain rate. The yield strength of solder is decreased with the increase of strain temperature and increased with the increase of strain rate. The stress-strain relationship of lead-free solder measured at the strain rates of 5×10

-4

s

-1

and 5×10

-5

s

-1

was compared with the experimental ones

and the calculated values were consistent with the experimental ones

indicating that the hyperbolic sine constitutive relation can be used to describe the flow stress of lead-free solder during hot compression deformation

where the thermal deformation activation energy Q is 61.863 23 kJ/mol.