Assembly-level reliability characterization of chip-scale packages

The reliability of the Elastomer-on-Flex Interposer Chip-Scale Package has been studied under thermal fatigue, out-of-plane deformation, humidity and thermal aging. Two versions of the Elastomer-on-Flex Interposer CSP (from a single source) have been characterized in this study-the 48-pin and 40-pin. Both the 40-bump and 48-bump versions have ball 0.3 mm (11.81 mils) in diameter solder balls at 0.75 mm pitch. Non-linear finite element models have been used to identify and predict the dominant failure mechanisms. The model predictions have been verified with accelerated test data. The results for all the dominant failure mechanisms have been bench-marked against existing technologies including overmolded PBGAs and rigid substrate flip-chip BGAs.