Power QFN down bond lift and delamination study

摘要

The PQFN device revealed down bond lift and delamination issues. Based on AES (Auger Electron Spectroscopy), XPS (X-ray Photoelectron Spectroscopy) and FTIR (Fourier Transform Infrared Spectroscopy) analysis it was possible to verify that a down bond contamination caused the failure. Cross sections of down bond wire for the failed unit showed a broken heel on the down bond. Furthermore, cracking between molding compound and lead frame was found. It was proven that the delamination caused the down bond lift and the broken heel. FEA (Finite Element Analysis) revealed that the delamination can lead to shear stress increase at the down bond heel.