ESD failure mechanisms of inductive and magnetoresistive recording heads

Dynamic temperature rise of shielded MR sensors during simulated electrostatic discharge pulses of variable pulse width

“…The instantaneous thermal conductance can also be determined from the ratio of P mr to ΔT mr at each time point (Equation 4), and is plotted in Figure 4 for τ p between 30 ns and 2 ms for stripes having a W of 7.6 or 11 and H of 1.26 to 1.84 μm. For a given geometry, the inverse of the slope of P mr versus ΔT mr at a fixed time ( T mr (40. ns)=-25+1.52 (P mr ) 1 T mr (100 ns)=+7+1.84 (P mr ) 1 T mr (150 ns)=-0+2.19 (P mr ) 1 T mr (250 ns)=+8+2.37 (P mr ) 1 T mr (500 ns)=+4+2.89 (P mr ) 1 T mr (900 ns)=-11+3.50 (P mr ) 1 40. ns 100 ns 150 ns 250 ns 500 ns 900 ns …”

“…A large body of work has been performed on the effects electrostatic damage (ESD) and electrical over-stress (EOS) on anisotropic (A) MR devices. Much work has been done showing the failure characteristics of current, voltage and power using a single time scale [1] More recent studies on giant (G) MR sensors have included a wide range of time scales [2,3]. Few studies, though, have focused on directly determining the temperature of the stripe, either experimentally [3,4] or with Finite Element Analysis [5] (FEA).…”

“…In the study of the current report, a one-dimensional finite difference analysis (1D FDA) model is done to ascertain approximate thermal properties of the materials, to validate the phenomenological model, and to understand the heating in the materials surrounding the MR stripe. Previously, Chang [5] reported on a three dimensional finite difference analysis model (3D FDA) to show the temperature rise of a shielded MR sensor during a 150 ns exponential pulse to simulate the human body model [1,6] (HBM). Though a 3D model is more accurate than a 1D model, for times below a few hundred nanoseconds, a 1D model is sufficiently accurate to elucidate the essential features of the sensor heating, and the computational times are significantly reduced for the latter.…”

Field-induced charged device model testing of magnetoresistive recording heads

“…Study of Fig. 3 reveals that the complete recording head is a 5 terminal device with two terminals for the thin-film inductive transducer (1,2), two terminals for the MR sensor (3,4) and one terminal for the substrate (5). The general equivalent circuit also shows that the recording head has 5 spark gaps.…”

“…[2,3,4,5] However, static sensitive devices can also be damaged by electricfields, either by field strength alone due to induced voltages [6], or by the rapid discharge when the device is grounded in an external field. [7] A standard test for integrated circuits (IC), known as the fieldinduced Charged Device Model (CDM), has been developed to measure the damage threshold when an IC is grounded in an extemal electric field.…”