Degradation of GMR and TMR recording heads using very-short-duration ESD transients

Electrostatic discharge (ESD) testing results for giant magnetoresistive (GMR) and tunneling magnetoresistive (TMR) recording heads using a direct charged device model (D-CDM) tester are reported for the first time. The D-CDM is intended to replicate the ESD event produced by metal-to-metal contact discharge that occurs as a charged component discharges to another object at a different electrostatic potential. This discharge, through a very short path to ground, corresponds to an extremely fast (<1 ns wide), high-amplitude current transient. The D-CDM tester produces a transient by first charging the device itself and then grounding the device with a mercury relay. The ESD testing was done in situ with a quasi-static tester (QST) on GMR recording heads. Resistance, amplitude, asymmetry, and transfer curves were recorded after each ESD event. D-CDM physical failure voltages are much lower (4-5 V) than the ones obtained with the human body model (HBM) (25-30 V). Magnetic failure threshold can be even lower. We also report some D-CDM damage on TMR recording heads.