Thermal effects in shielded MR heads for tape applications

Head reliability of AMR sensors based on thermal stress tests

“…For the data shown in Figure 1(b) with n ϭ 3, the J Ϫn term changes EM by a factor of only ϳ3 for n and the current range of 17.7 to 25.6 mA, while the activation energy of 2.1 eV results in a factor of ϳ3000 increase in EM for the temperature range of 295ЊC to 424ЊC. Since interdiffusion rates also increase with a decrease in stripe thickness, 4.5 is an upper limit for n. An accurate determination of n and of the contribution of interdiffusion and oxidation requires the data to be fit using Equation (10) for 2 , and the introduction of additional processes for interdiffusion and oxidation into Equation (5). However, a comparison of experiments on sensors designed with large differences in t mr , gap, H, and W can reveal electromigration effects because the current density results in a fixed temperature [12].…”

“…Magnetic changes ascribed to stress relief on materials with nonzero magnetostriction have been observed in materials annealed at temperatures as low as 100ЊC [30]. To achieve the desired magnetic properties, the magnetic materials are deposited at elevated temperatures [5] or are annealed at elevated temperatures subsequent to deposition. To achieve the desired magnetic properties, the magnetic materials are deposited at elevated temperatures [5] or are annealed at elevated temperatures subsequent to deposition.…”

“…In forming AMR sensors, the magnetic materials are deposited on a wafer as thin sheets by a sputtering ionbeam deposition or by a plating process. Because the magnetic materials have thermal expansion coefficients different from those of the materials surrounding them, they will be under stress from the heating and cooling cycles during processing [30] and operation [5,15,31]. Because the magnetic materials have thermal expansion coefficients different from those of the materials surrounding them, they will be under stress from the heating and cooling cycles during processing [30] and operation [5,15,31].…”

“…While published papers have addressed reliability associated with large resistance changes or drops in amplitude [5][6][7][8][9], few, if any, have directly addressed changes in signal distortion or magnetic-transition densitydependent responses (Wallace spacing losses) [10]. Signal distortion arises from a nonlinear response to magnetic field magnitude or direction.…”