25 Jul
2012
25 Jul
'12
1:12 a.m.
On Wed, 25 Jul 2012, Dave McGuire wrote:
On 07/25/2012 03:33 AM, Tothwolf wrote:
The idea behind the metalized plastic type bags is to shield the parts
inside the bag from potential ESD outside the bag.
As Will pointed out, if the bags are too
conductive (just like the
black conductive bags), they don't really protect against external ESD.
Why would this be? The idea is to dissipate very high voltages that has
almost low current behind them, because the gate dielectric in MOSFETs
is very thin and can be punctured by high voltages, so you need to avoid
large voltage differentials between pins. Higher conductivity achieves
that just as well. I can "sorta" see what Will was talking
about when too much current
flows too quickly, producing charges in nearby components via
electromagnetic induction. Is that the issue here?
If the bag itself is conductive between the inside and outside (fully foil
or carbon black) then just touching the bag if you are at a different
potential can still zap whatever is inside the bag.