Current transients and the Guzik: a case study and methodology for qualifying a spin stand for GMR testing

Repeated dynamic electrical test of current generation anisotropic magnetoresistive (AMR) heads indicated that ESD exposure was likely during test, characterized as a decline in amplitude over time. Giant magnetoresistive (GMR) heads failed catastrophically upon mounting to the Guzik spin stand. By evaluating AMR performance under repeated controlled test sequences, as well as direct current transient measurement techniques, we determined that the particular configuration of software and hardware which was being used during this test generated current transients across the recording head of up to 40 mA peak currents, which was believed to cause both the AMR degradation and the GMR failures. By modifying the hardware and software, the problem was successfully resolved. Qualification of electrical test equipment using current transient measurements was found to be invaluable in fully understanding and correcting current transient problems in test processes.