Metal migration in epoxy encapsulated ECL devices

摘要

The present investigation identifies migrative resistive shorts as the primary mode of failure for ECL power devices from field failures. In the present investigation, a number of analytical tools have been applied in order to identify and characterize the failure mechanism. These techniques included environmental scanning acoustic microscopy (ESEM), energy dispersive x-ray spectroscopy (EDX), scanning acoustic microscopy (C-SEM). Devices which were analyzed were selected so as to compare control, and untested devices with field returns which had failed as a result of either shorts between bond pads or the presence of leakage paths between bond pads. The failed devices from field returns were in two categories: returns with no destructive analysis performed, and returns with destructive analysis. Hence we were able to reach conclusions on the effect of destructive analysis on disturbing the failure site. We also performed accelerated stress testing on devices from a single date lot so as to attain projected mean time to failure and hence develop a statistically valid reliability model.