Modeling and experimental investigation of damage initiation and propagation of LQFP package under thermal cycle

Thermo mechanical fatigue and damage have been always an issue for solder joint materials used in microelectronics. Accurate damage and crack prediction is important to define the life cycle of these joints. This paper provides a finite element modeling approach used in combination with continuum damage model in order to determine damage level, update material’s constituent properties and to predict the damage initiation, damage propagation and time in Low Profile Quad Flat Package solder joint. The successive initiation and propagation of a crack is calculated by a non-linear visco-plastic finite element model. Based on the amount of damage they incur in each stage, their constitutive properties are upgraded. Mesh elements with successive damage are suppressed from the structure. The results of finite elements analysis show that they are softened and can therefore stand more stress as the elements accumulate damage leading to the decrease of damage accumulation level. The initiation site and propagation path were showed very accurately and were confirmed experimentally with scanning electron microscopy.