Backside Die-Edge and Underfill Fillet Cracks Induced by Additional Tensile Stress from Increasing Die-to-Package Ratio in Bare-Die FCBGA

Changes in die-to-package ratios could introduce some additional harmful tensile stress. If material sets to build the packages are identical, and with only slight tweaks in dimensions of the package; the common assessment is larger die size or larger package size could yield worse reliability results. This school of thought could lead to wrongly qualifying by similarity or extension. This study demonstrates that the die-to-package ratio should not be neglected. And as a result, it will reshape the practice of qualification by similarities.