ESD events of cabled GMR sensors
ESD damage from cable discharge events (CDEs) of magnetoresistive sensors is a major problem in manufacturing of magnetic tape and hard disk drives. CDEs initiated by contact to the cable pads used to connect to external electronics represent one source. This paper addresses CDEs from other points of contact, including capacitive coupling to metal objects contacting the cable. In order for capacitively coupled ESD events to damage the sensor the capacitive coupling of the two sensor leads to the external object being discharge must be different.
ESD damage and solutions in tape head manufacturing
Magnetic tape heads use a multiplicity of highly ESD sensitive read sensors. With 36 or more sensors per head in a magnetic storage tape drive, a loss in a manufacturing environment of 1000 ppm per sensor is very costly. ESD damages caused by manufacturing processes, fixtures, material and faulty testers are investigated and reviewed. A new type of ESD failure is revealed in the study. Solutions are suggested to improve and amend the observed problems.
Estimating Fatigue Curves With the Random Fatigue-Limit Model
In a fatigue-limit model, units tested below the fatigue limit (also known as the threshold stress) theoretically will never fail. This article uses a random fatigue-limit model to describe (a) the dependence of fatigue life on the stress level, (b) the variation in fatigue life, and (c) the unit-tounit variation in the fatigue limit.We fit the model to actual fatigue datasets by maximum likelihood methods and study the fits under different distributional assumptions. Small quantiles of the life distribution are often of interest to designers. Lower confidence bounds based on likelihood ratio methods are obtained for such quantiles. To assess the fits of the model, we construct diagnostic plots and perform goodness-of-fit tests and residual analyses.