Fatigue life estimation of a stretched-solder-column ultra-fine-pitch wafer level package using the macro-micro modelling approach

This paper presents package warpage and interconnect fatigue life estimates of stretched-solder-column interconnections in a 20mm/spl times/20mm package with 100 /spl mu/m pitch. The modelling was carried out in two stages using the macro-micro modelling approach. The effect of interconnection height, as well as chip thickness and substrate CTE (coefficient of thermal expansion) on fatigue life is discussed. The results suggest that the substrate CTE will continue to be the key factor in determining the thermomechanical reliability of a large package with small interconnections.