Effect of 1 ns to 250 ms ESD transients on GMR heads

The performance degradation of GMR heads subjected to human body model ESD transients is well documented. In this paper, we investigate the performance degradation of GMR heads subjected to ESD transients with time constants ranging from 1 ns to 250 ms. A charged device model fixture and a variable pulse-width model RC circuit were developed to produce the ESD transients. Dynamic electrical testing and quasi-static testing were used to characterize the devices before and after ESD. Both the voltage across and current through the sensor were measured simultaneously in order to estimate the instantaneous resistance and thus the temperature of the devices during the ESD transient. Two head designs were compared in this study. It is shown that the tested devices fail when the average temperature, estimated from the device resistance at uniform temperature, reaches about 275/spl deg/C regardless of the duration of the pulse.