Kurt Pawlikowski wrote:
Keith,
As far as I know, resistors, capacitors and most (if not all) diodes
will not be damaged by ESD. Note: Diodes will either conduct when
forward biased or "zener" and conduct when backwards biased - thought
I'm not sure about "special" diodes [barrier, shotkey (sp?), and the
like]. And, normal ESD damage is caused by high potentials arching
within the component. I believe diodes have plenty of capacity to
absorb the power, either forward or reversed biased. Capacitors will
simply "charge" (which is why attaching a capacitor to a Van de Graph
generator is a Bozo no-no). At any rate, I have never heard of any of
these types of components being damaged by ESD: Has anyone?
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
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