A modified single lap shear test configuration, based on the Iosipescu geometry, is proposed to characterize mechanical properties of solder alloys. In the method, an auxiliary device (extension unit) is employed to improve the accuracy of measurement. The extension unit is attached directly to the test area. The unit converts shear displacements to axial displacements, which are subsequently captured by a high-resolution extensometer. The extension unit allowed measurement of shear deformations without compensating machine and grip compliance.

The proposed test configuration is utilized to characterize the constitutive properties of lead-free solder. Experimental parameters are obtained for (1) a partitioned model, where the elastic, rate-independent plastic and rate-dependent creep behaviors are all separated and (2) a unified creep-plastic model.

Reliability assessment of lead-free solder joint is performed by calibration of virtual qualification model for leaded packages with lead-free solder.