Numerical analysis of fine lead bonding-effect of pad mechanical properties on interfacial deformation

The present study was carried out for the purpose of understanding solid state inner and middle lead bonding, especially the effect of pad mechanical properties on the interfacial deformation processes between lead and pad based on a computer simulation that was carried out by using a finite element method (FEM). As the mechanical properties largely depend on temperature, we discuss the influence of temperature on the effect of pad mechanical properties, i.e., the pad temperature is different from the lead temperature. It is suggested that the interfacial extension reaches greater than 20% for only 10% lead reduction as the pad temperature is 200 K higher than the lead temperature. We further discuss the effect of the substrate temperature on the bond strength, based on the calculated and experimental results.