Effects of Solder Ball Geometry on Lap Shear Creep Rate

Abstract

Effects of solder ball geometry on lap shear creep deformation were investigated using the three-dimensional (3-D) finite element method (FEM). The meridian of the solder ball before creep, calculated using the energy principle, was very close to the circular arc which was assumed for subsequent calculations. As solder with a given volume and pad area was varied in geometry from convex to concave, lap shear strain rates increased by two to three orders of magnitude, implying that the solder geometry effect must be taken into account for accurate assessment of lap shear results. Finally, a simple method which can handle the solder geometry effect is proposed.