I. Introduction
The well-known backside die-edge chip outs and underfill cracks are reported to be associated with tensile stress in many works [1]-[6]. In this work, how changes in die-to-package ratios could introduce some additional harmful tensile stress are demonstrated. Since the use of flip-chip Ball-Grid-Array (FCBGA) has increased largely because of the demands of performance in integrated circuits (ICs), studies of integrity and reliability of this type of package are needed. Furthermore, based on the results of this study, the thoughts of qualifications by similarities or extensions should be reviewed and be used carefully.