Dependence of Flex on Suspension Capacitance on Human-Body-Model-Electrostatic-Discharge Affected TMR Head

Abstract

Electrostatic discharge (ESD) effects on GMR recording heads have been reported as the major cause of head failure. Since the information density in hard-disk drives has dramatically increased, the GMR head will be no longer used. The tunneling magnetoresistive (TMR) read heads are initially introduced for a 100 Gbit/in2 density or more. Although the failure mechanism of ESD in GMR recording head has not been explicitly understood in detail, study to protect from this effect has to be undergone. As the TMR head has been commercially started, the ESD effect is closely watched. This is the first time report of the TMR equivalent circuit in order to evaluate the ESD effect. A standard human body model (HBM) is discharged across R+ and R- where the capacitance of flex on suspension (FOS) is varied. It is intriguingly found that the electrical characteristic of the TMR head during discharge period depends on discharge position. This may be explained in terms of asymmetry impedance of TMR by using adapted Thevenin’s theory. The effect of FOS component on TMR recording head is also discussed.