[Elecraft] ESD prevention

[Ron D'Eau Claire]

RC asked:
> Hi Gang
> I am slightly confused! When using ESD protective
> measures you should use:
> 1) a wrist strap connected to
> 2) an anti-static mat.
> 3)You should build/work on the anti-static mat to be
> certain that all components (and you)are at the same electrical 
> potential there by minimizing any ESD damage. 4)should you connect the 
> anti-static mat to the carpet with a long clip lead?
> 5)or house electrical ground?

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Here's the scoop from the KX1 manual. It's typical of the Elecraft manuals:

Preventing Electro-Static Discharge Damage

Problems caused by Electro-Static Discharge (ESD) may be very
difficult to troubleshoot because damaged components may still
operate somewhat rather than fail completely. We strongly recommend
you take the following anti-static precautions (listed in order of
importance) to avoid trouble:

. Leave ESD-sensitive parts in their anti-static packaging until
you install them. The packaging may be a special plastic bag
or the component's leads may be inserted in conductive foam.
Parts which are especially ESD-sensitive are identified in the
parts list and in the assembly procedures.

. Wear a conductive wrist strap with a series 1 megohm
resistor. If you do not have a wrist strap, touch a ground
briefly before touching any sensitive parts to discharge your
body. Do this frequently while you are working. You can
collect a destructive static charge on your body just sitting at
the work bench. DO NOT attach a ground directly to
yourself as this poses a serious shock hazard.

. Make sure your soldering iron is ESD-safe and has a
grounded tip

. Use a grounded anti-static mat on your work bench.

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"Grounded" means connected to ground. The mains ground is normally used for
this. In general it's a bad idea to have a ground connection separated from
the mains ground. (In many places it's a violation of the electrical codes.)
It *is* a good idea to make sure your mains grounds are connected! A very
simple tester is available in almost any hardware store that plugs into an
outlet. It tells you if the mains hot and neutral are connected to the right
sides of the outlet and whether the ground is connected. It's rather
astonishing to me (and un-nerving) just how many outlets in new homes and
recently re-wired homes have no ground connection at all! 

Your carpet is not conductive. That's why you can develop a huge static
charge on it. Connecting a wire to it won't do much. The idea of the wrist
strap is to bleed off any charge you do accumulate so that even if you have
a 'killer' carpet in the room, your body will be safely at ground potential
when you touch the ESD-sensitive parts. You can accomplish this just as well
without a wrist strap by briefly touching a known good, unpainted ground
before touching the parts, but be aware of the warning to do this
*frequently*. Squirming around on a cloth seat or sliding our foot on the
floor can produce a killer static charge in an moment, so keep touching that
ground before picking up each part. 

Finally, be aware that it's not just individual parts that need protection.
Normally parts in a circuit will have a dc path to ground through resistors,
coils and other components that protects them from most ESD dangers but,
when you pull a board out of the rig, some circuits are opened by
disconnecting the cables and connectors. It's rare to damage the assembled
rig unless there's a huge pulse such as a near strike by lightning, but
individual boards should be treated with the same respect you'd give the
most sensitive individual component. 

Ron AC7AC