John,
Interesting. The link is related to CMOS, which is extremely
sensitive to ESD.
Capacitors: I don't understand how a cap can be damaged unless ESD
has a transient faster than the cap can charge or there is enough
current to charge the cap beyond it's limits. But isn't that what the
cap is supposed to do? Yes, once the voltage across the cap is exceeded,
all bets are off!
If you're talking about caps in tube equipment, I think the problem
there would more likely be explained by degrading/defective components,
or components that were exposed to high voltage, relatively high power
discharges (i.e., not ESD).
I can understand thin film resistors (the higher the resistance, the
more likely an arc). Not sure about diodes. I'm thinking that if the ESD
has a transient faster than the diode can handle, maybe. It just seems
to me that if forward biased, it simply conducts. If backward biased, it
acts like a zener (which conducts).
Some interesting links...
http://www.aiinet.com/documents/html/AI180hwman/m0699/aihxa.htm
http://www.electrostatics.net/library/articles/ESD_damage.htm
http://www.evaluationengineering.com/archive/articles/1102esd.htm
http://focus.ti.com/lit/an/ssya010/ssya010.pdf
http://www.ce-mag.com/archive/03/03/henry.html
http://www.e-gizmo.com/ARTICLES/ESD/ESD2.HTM
http://electrostaticsolutions.blogspot.com/2005/06/are-capacitors-esd-suceptible.html
Some of these have pictures (always interesting!). The last link
talks about capacitors. One of the links is very IEEE technical. More
fuel for the fire! {'-)
Regards,
kurtt
Kurt Pawlikowski, AKA WB9FMC
The Pinrod Corporation
[EMAIL PROTECTED]
(773) 284-9500
http://pinrod.com
John Huggins wrote:
John Huggins wrote:
While it is true caps can be relatively sturdy, capacitors are
damaged by ESD if the high voltage appears across their leads despite
what one might think of "charge time." Any usual thinking of how
caps work begins to break down once the peak voltage (not rated
voltage, but whatever the much higher real peak voltage is - ie
400-1000V for a 100V ceramic) is exceeded even with the low low
power of an ESD event. Audiophile Tube Stereo freaks recognize caps
that have been zapped because they develop pinholes in their
dielectric and begin to add pop and hiss to their "sound."
Thin film resistors are also easily "hurt" by ESD. Same with diodes.
NASA is particularly anal about this (for obvious reasons) and have
this to share...
http://workmanship.nasa.gov/wppr_comp_c2mos.jsp
While it is true not all ESD events cause damage. The outcome of a
discharge to a sensitive device or assembly will depend on many
factors, including:
- device sensitivity
- severity of ESD stress
- actual strike site
Some components handle ESD better than others, but none are entirely
immune.
If we are to assume Elecraft handles their parts with the care the
parts probably received on their way to Elecraft (I hope this is so)
and then delivered them to us with the same care, we should not break
the chain of proper handling.
ESD is so easy to do correctly why not treat all the parts with the
same level of respect. The chances of success are probably
measurably better.
John
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
