Discharge Current From Coated Wire to GMR Head

The giant magnetoresistive (GMR) head used in magnetic recording is an extremely sensitive device that is sensitive to electrostatic discharge (ESD). A generally available coated wire that is electrified on its surface can increase the potential of the copper core. When the wire is touched to the GMR head terminal, the discharge current can damage the sensor of the GMR head. Four types of wires were measured for three lengths each. Resin-coated wires were electrified from 20 V to more than 1 kV. The peak current discharging to the GMR head ranged from 100 mA to more than 1000 mA. A resin-coated wire as short as 5 cm was found to damage the GMR head. Among the wires examined herein, only the enameled wire is recommended to connect the GMR head because no charge or discharge currents were observed for this wire. When an ionizer is used to neutralize the tribocharge on the surface of the wire, the remaining charge in the copper core depends on the effectiveness of the neutralization process. A wire with an antistatic coating is required in order to reduce the ESD threat to sensitive devices such as the GMR head