A study of diode protection for giant magnetoresistive recording heads

ESD testing of giant magnetoresistive (GMR) heads with diode protection is described. While the use of diodes did increase the magnetic and failure vo ltages of the GMR head, the magnetic failure voltage was increased much les s than the resistance failure voltage. This results in an unfortunate side effect, which is to dramatically increase the range over which magnetic dam age occurs without a corresponding resistance change. This problem was espe cially clear for the case of two diodes in series. The current flow through the GMR head and diode were measured and agreed with SPICE circuit simulat ion results. The difference between magnetic and resistance protection is d ue to the nonlinear clamping behavior of the diode. We conclude that seriou s magnetic damage will be the predominant failure signature for GMR heads w ith ESD protect diodes. (C) 2000 Elsevier Science B.V. All rights reserved.