A Finite-Element and Experimental Analysis of Stress Distribution in Various Shear Tests for Solder Joints

Solder alloys are commonly tested with shear tests to study their mechanical properties or low-cycle fatigue performance. In this work, the suitability of various shear tests for quantitative solder-joint testing is investigated by means of the finite element method. The stress state and stress distribution in the following well known geometries are studied: the double-lap test, the ring and plug test, the losipescu test, and two single-lap tests. A new test geometry, the grooved-lap test, is introduced and compared to the conventional tests. The results of simulations with an elastic material model in plane-strain indicate that considerable differences in the purity of the state of shear (rε = −ε₁/ε₃) as well as in the stress distribution in the joint exist among the shear tests. However, simulations with a nonlinear material model show that stress inhomogenities are smoothed by the plastic and creep deformation occurring in the joint. Optical measurements of the deformation of real single-lap and grooved-lap joints show that the single-lap joint rotates slightly during creep, whereas in the grooved-lap joint no rotation can be detected. This confirms the simulation results that in the single-lap test the initially nonuniform stress distribution changes during creep, and in the grooved-lap test the uniform stress distribution remains constant through the test.