Assembly Reliability of eWLP, Die- and Die-Size BGA

This paper presents assembly challenges as well as solder joint thermal-cycle reliability of mixed area array packaging and flip-chip die technologies. These were: (1) eWLP-LGA, 196 land patterns, 0.4mm pitch, (2) Cu-FC (CC80), flip-chip die with copper pillar, 1048 bumps, and (3) CVBGA, 360 balls, 0.4mm pitch and with either lead-free or tin-lead solder balls.Twenty-seven (27) PCBs were assembled with a number of variables and rejected assemblies. Acceptable assemblies with and without underfill were subjected to thermal cycling between –40°C and 125°C for solder-joint reliability characterization and failure-mechanism assessments. The 2-parameter Weibull plots delineated cumulative failures and optical X-sectional characterization presented failure mechanisms and locations.