Creep of solder interconnects under combined loads

An exact analysis is presented for the creep deformation of solder interconnects subjected to the actions of bending moment and axial force. Dimensionless interaction curves and charts which relate the variables, axial force, location of neutral-axis, maximum bending stress and strain rate, bending moment and change in curvature rate are also provided for engineering practice convenience. Furthermore, the tangent-modulus buckling loads of centrally loaded solder columns and a simple formula for the critical time to buckling are determined. The constitutive relationship of the solder interconnects is described by ε=(ε₀^´+m´tⁿ) sinh σ/σ₀