Influence of Package Trace Properties on CDM Stress

CDM current waveform properties show a strong dependence on pin type and location due to package transmission line effects in large BGAs. I/O pin waveforms have a depressed peak, slower rise time, and increased pulsewidth compared to power supply waveforms, with the offset increasing with the distance from the package center. Simulations illustrate that the internal current through the ESD protection network on the die can deviate significantly from the external current observed in the CDM system for long package traces.