Analysis of abnormal ESD failure mechanism in high-pin-count BGA packaged ICs due to stressing non-connected balls

An abnormal failure mechanism due to ESD stressing on the Non-Connected (NC) balls of a high-pin-count (>500 balls) BGA packaged IC is presented. Failure analyses including Scanning Electronic Microscopy (SEM) photographs and the measurement of current waveform during ESD zapping had been performed to give clear explanation on this unusual phenomenon. New protection solutions have been proposed to solve this problem in a BGA packaged IC product with an improvement ESD robustness, which can sustain 3-kV HBM and 300-V MM ESD stresses.