BUMP STRUCTURAL DESIGNS TO MINIMIZE PACKAGE DEFECTS

摘要

The mechanisms for forming bump structures enable forming bump structures between a chip and a substrate eliminating or reducing the risk of solder shorting, flux residue and voids in underfill. A lower limit can be established for a cc ratio, defined by dividing the total height of copper posts in a bonded bump structure divided by the standoff of the bonded bump structure, to avoid shorting. A lower limit may also be established for standoff the chip package to avoid flux residue and underfill void formation. Further, aspect ratio of a copper post bump has a lower limit to avoid insufficient standoff and a higher limit due to manufacturing process limitation. By following proper bump design and process guidelines, yield and reliability of chip packages may be increases.