A Cost-Effective Structure for Secondary Discharge Control to Improve System-Level ESD Immunity of a Mobile Product

A structure embedded in a printed circuit board is proposed to control secondary discharge currents and improve the system-level electrostatic discharge (ESD) immunity for a mobile product with a metal frame. Noise voltages and discharge currents were measured and analyzed according to several secondary discharge paths, such as an air arc, a voltage suppressor device, and with the interlaced suppression device. ESD events that caused soft failures of a real commercial mobile product were tested while a high-definition video was playing. System-level ESD-induced noise and soft failures were cost effectively reduced by the interlaced suppression device.