Effects of ESD transients on the properties of GMR heads

Simulated ESD transients with pulsewidths from 0.1 nsec to 10 nsec were applied to GMR heads. From 1 to 10 nsec essentially no changes in failure voltages are observed, but below approximately 1 nsec, failure voltages increase. The time marking a transition between the two regimes, ∼1 nsec, and the dependence of failure voltage on either side are qualitatively consistent with the expected transition from adiabatic failure for short pulses to a more steady-state thermal failure for longer pulses, but true adiabatic behavior is not clear for short pulses. The ratio in voltages inducing resistance versus amplitude failure remains constant over all pulsewidths and for both voltage polarities, suggesting thermal degradation is dominant. Although magnetic failures occur at lower voltages than resistive, no observations here suggest that either the magnitude or direction of the pulse-induced magnetic field is a critical parameter in head failure.