Drive-level instabilities correlated to quasi-static field testing

Abstract

We investigated the relationship between in-drive servo error counts and drive-level quasistatic test (QST) to determine the effectiveness of using QST to screen heads which may be unstable immediately following a write operation in the drive. Waveforms, which generated servo errors, were also captured. QST did not appear to correlate well with servo errors for heads which required a write operation to cause instability. This is likely due to the transient nature of such instabilities.