component overstress

George Stevens/UB Networks (George_Stevens@UB.com)
11 Mar 96 15:04:28 EDT

I am currently investigating a phenomenon that is occuring associated with 64k
x 4 Srams
from Quality Semiconductor. Field failures are occuring characterized by
component failures,
which, when a Failure Analysis is completed by the manufacturer, finds an input
open and
carbon deposits observed on Vcc and ground pins. This, reportedly, indicates
high current draw
caused by "overstress" in our application. I am currently attempting to
measure over/undershoot
and voltage spike anomolies on the board but have found nothing that violates
the manufacturers
spec yet. I have been told that contention can also overstress an input, I
assume when two or
more drivers attempt to pull the input to the Sram low. Is this possible??

Anybody have any history on this device or ideas on what other signal anomolies
may cause an overstress
on an input stage?

Thanks, George Stevens, Sustaining Engineer
gstevens@ub.com