Impact of Metallic Robotic Arms on IEC 61000-4-2 ESD Waveform Integrity and Human Operator Replication

Reproducibility remains a major concern in system-level electrostatic discharge (ESD) immunity testing, particularly in the characterization of the second peak of the IEC 61000-4-2 waveform. While the 2025 revision of the Standard introduces new parameters and stricter setup constraints to improve waveform consistency, it does not address the influence of the human operator during ESD testing. Robotic testing systems offer improved repeatability by eliminating operator-induced variability, but the impact of the robotic arm—especially when constructed from metal—on waveform integrity has not been systematically investigated. This study evaluates the influence of grounded and ungrounded metallic robotic arms on the ESD waveform using two compliant generators and two grounding cable arrangements. Significant waveform distortions were observed, particularly with directly grounded arms. To address this, a series resistor is proposed for grounded configurations, while clamp-on ferrites are recommended for ungrounded setups. The proposed modifications enable robotic test setups to replicate human operator influence more accurately, improving reproducibility across automated ESD testing environments.