Cleaning Organic Residue in High-Pb Flip Chip Ball Grid Array Interconnection

This paper discusses the formation of organic residues on high lead (Pb) Flip Chip Ball Grid Array (FCBGA) package. Flux used for Control Collapse Chip Connection (C4) die attachment during assemblies could remain on the die surface as organic residues, thus affecting the Integrated Circuit (IC) performance. Therefore, the effect of implementation flux-cleaning process on the die cleanliness was evaluated in this study. Design of Experiments (DOE) for cleaning chemical parameters using water-based solvents was carried out to investigate the flux-cleaning efficiency. Referring to the IPC- TM-650 test manual of contaminants extraction approach, the test packages were then evaluated in-situ via Fourier Transform Infrared Spectroscopy (FTIR). FTIR results show that there is organic flux residue detected prior the cleaning process. Notably in contrast, there is no residue detected after the cleaning process. This clearly indicates a positive correlation of the cleaning process to the DOE implemented.