In this article, electrostatic discharge (ESD) induced soft failures (SFs) of a USB3 Gen1 device are investigated by direct transmission line pulse injection with varying pulsewidth, amplitude, and polarity to characterize the failure behavior of the interface and to create a SPICE model of the voltage and current waveform dependent failure thresholds. ESD protection by transient-voltage-suppression diodes is numerically simulated in several configurations. The results show viability of using well-established hard failure mitigation techniques for improving SF robustness. A good agreement between numerical simulation for optimized board design and measurements are achieved. A novel concept of SF system efficient ESD design is proposed and demonstrated to be effective for making decisions during early product development, in board designing and prototyping phase.