The Mechanism of The Die Crack in exposed Pad Quad Flat Package(ePad QFP) with Large Die due to Die-attach Adhesive with high modulus

Thermal-enhanced plastic packages, such as exposed Pad Quad Flat Package (ePAD QFP), are more sensitive to thermal stress and warpage. As a result, thermal stress and warpage in ePAD QFP can lead to severe die cracking. This stress and warpage are mainly due to the thermal mismatch of packaging materials with different coefficient of thermal expansion (CTE). In particular, the die attach adhesive plays an important role in controlling stress and warpage in the package. In this paper, both experimental data and simulation were employed to gain a better understanding in a stress development and failure mechanism in ePAD QFP with a large die. Theoretical die-attach adhesives with different modulus were used for the evaluation of die crack and delamination by analysis of finite-numerical element method (FNEM). And the effect of the adhesion between Si die and Die-attach adhesive on the die crack was also discussed in this paper by FNEM. The simulation for thermal stress due to CTE mismatch was done by shadow ...