Effect of flip-chip package parameters on CDM discharge

CDM peak currents (I_peak) were studied for the same I/O pin on different dies and flip-chip packages. It is found that I_peak has strong correlation with linear function of two capacitances: die-to-lid capacitance (C_DUT) and C_DUT normalized per die area (C_DUT/A). The proposed physical model relates CDM current to the two competing discharge paths. The local path is from Si-substrate, where the charge collected from a few millimeters radius. This part of I_peak is a function of C_DUT/A. The global path is through a package ground plane, where the charge is collected from Si-substrate via metal routing to the taps. This part of I_peak is a function of C_DUT.