Fri, 16 Apr 1999 17:14:13 -0400
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I'm sorry but all those years of EE training and mindset make me cringe
and cry out whenever this topic comes up......
It's unfortunate, but I have met many good technicians with an "I
shouldn't but I do" attitude. If they ever had chance to see pictures
from an electron microscope showing the actual internal damage to an IC,
they would have more respect for static.
The biggest problem with static electricity is that - most of the time -
it does not immediately "fry" the IC, so everybody assumes they "got away
with it". But in reality what has happened is that the high voltage
charge caused a "wound" within the IC and that wound causes premature
failure of the circuit, or a pathway (that has had part of the metal
melted away by overvoltage) decreases the current flow enough to prevent
full capacitance levels so a dynamically refreshed RAM has random and/or
partial memory loses in some or all of it's cells, or the increased
resistance in a pathway causes a slight delay in the timing of a signal,
or.......
You can damage a chip with a charge so small that you never even feel it
or notice it.
Remember --- the chips have been designed to work at 5 volts (or less) so
it doesn't need a 10 Kilovolt charge that leaps two feet across the room.
Jim Meagher
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----- Original Message -----
> > I've read that you should leave the PC plugged in so it will be
> > grounded (and wear a grounding strip attached to the case), that's
> > not right?
>
> True, it is better to leave it grounded, however if the chance
that you
> will mistakingly turn it on is too great than leave it unpluged. There
is no
> right answer to all this, I have worked on many systems without a
grounding
> strap, is that smart? Well not really, but I have gotten away with it.
The
> odds of you carrying a static charge that will fry a CMOS junction is
small,
> but it is there and preventable
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