Moisture Induced Interface Delamination for EMI Shielding Package

EMI (Electromagnetic Interference) shielding is widely used in electronic modules to reduce the coupling of radio waves, electromagnetic fields and electrostatic fields and to enhance the electric performance. In the paper, interface delamination during reflow after MSL (Moisture Sensitivity Level) precondition is discussed in both EMI shielding packages and non-EMI shieling packages. It is found that interface delamination is initiated between mold compound and solder mask, then propagates to the interface between die and DAF (Die Attach Film) for EMI shielding packages, while no delamination is detected for non-EMI sheiling pacakges. Experimental results also show a big difference of moisture absorption between the shielding and non-shielding packages. Furthermore, FEA (Finite Element Analysis) modeling is introduced to analyze moisture absorption in both shielding and non-shielding packages. The moisture-mechanical-vapor pressure is also used to simulate the stress under reflow after MSL. It shows that the vapor pressure in EMI shielding packages is higher than in non-EMI shielding packages under the same moisture precondition.