| In current digital age, electronics industry is becoming one of the most dynamic, fascinating, and important industries in the world. The major trend in electronics industry is to make products smaller, lighter, and faster, while at the same time, to make them more powerful, functional, reliable and less expensive. Greater miniaturization of the products moves electronics industry towards surface mount technology, where the solder joints provide both reliable electrical and mechanical interconnection. This brings the concern of thermal stresses in the solder joints introduced by thermal mismatches between different materials. Thus the reliability of electronic products becomes an important issue in the electronic packaging. This research is focused on the study of the reliability of electronic packaging by means of fundamental micro-mechanics in terms of experiments and numerical analysis. A thin strip specimen is specially designed to investigate the thermo-mechanical properties of packaging materials. By using the thin strip specimen, a series of tests including tensile, creep and fatigue has been carried out for packaging materials, such as solder alloys and underfills. Thus, a consistent and reliable material database for reliability assessment is established. Then a combined experimental (laser moire interferometry technique) and numerical (FEA) study is conducted to investigate the nonlinear behaviors of package materials. It is found that analysis error can be caused if the visco nature for solder and underfill is neglected. Consequently, Strain-based approach combined with a unified viscoplastic constitutive model, strain rate-dependent plasticity model, in finite element analysis is applied to the life prediction. A unique test/simulation/validation/reliability assessment vehicle has been established and successfully applied to the reliability assessment and life predication of great industrial interests. |
