ESD events of cabled GMR sensors
ESD damage from cable discharge events (CDEs) of magnetoresistive sensors is a major problem in manufacturing of magnetic tape and hard disk drives. CDEs initiated by contact to the cable pads used to connect to external electronics represent one source. This paper addresses CDEs from other points of contact, including capacitive coupling to metal objects contacting the cable. In order for capacitively coupled ESD events to damage the sensor the capacitive coupling of the two sensor leads to the external object being discharge must be different.
A study of ESD protection means of cabled GMR sensors
Giant Magnetoresistive (GMR) sensors are used to detect magnetic transitions written onto magnetic media. They can be damaged by ESD transients generated during the highly manual assembly process. In this paper we discuss various protection means such as dissipative cables, diode protection and dissipative shunting between sensors and to ground.
The thermodynamics of physical and magnetic changes to AMR sensors from EOS at variable pulse widths
Damage from Electrostatic Over-Stress (EOS) to shielded anisotropic magnetoresistive (AMR) sensors used for magnetic tape storage devices were studied using square wave voltage pulses. Changes to the sensor's physical and magnetic properties were measured after each of a number of sequential pulses. The change in sensor resistance and magnetic amplitude and asymmetry were each fit to a thermodynamic model. Two processes were observed: Annealing and degradation, with respective activation energies of 2.1plusmn0.1 eV and 2.9plusmn0.1 eV. The annealing was associated with a slight decrease in sensor resistance and an increase in AMR asymmetry. The degradation was associated with a decrease in AMR asymmetry and amplitude, and an increase in sensor resistance.