[Elecraft] ESD precautions?

[John A. Ross [RSDTV]]

Bill

ESD is a silent and cunning enemy, people have made careers out of nailing down processes to keep it
under control.

The possibility of ridding yourself of the beast in a hot, humid or possibly dusty environment,
possibly with nearby HT sources is pretty hard. Best you can hope for is to train the beast to
behave.

It will have a direct attack on you by direct damage or it may partially damage the wire bonding or
contact area on your IC and leave a badly performing device (in case of op-amps, plls etc) or the
damaged device might work initially and may just sit there waiting to fail prematurely after a few
months giving rise to heartache and pain in the middle of that important contact (not counting
debugging the fault, a quite different skill & discipline to building the kit itself).

It is a matter of risk, discharging yourself to a good clean ground is good practice, but as ESD
effectively will discharge across most PD's then leaving yourself at 0 potential (which you will
never be) and picking up a part at a higher potential, and getting a discharge is also a risk.
Components and per-built PCB assemblies can also hold a charge.

A decent conductive mat connected to a clean ground via a high impedance (1-10M) path is a good
start, this will kill off most of the charge, your iron and wrist strap should also be connected to
the mat via the same GND path so all items are at the same PD. 
Other than for body discharge, direct discharge to GND should be avoided as an uncontrolled
discharge is a violent activity. 
Tools should be left on the mat if possible until needed. 
All parts of the kit you are working on should be kept on the mat as well, any parts in AS foam
should be left there until absolutely necessary. 
Your environment should be cool and dust free if possible. You could go the whole road and start
looking at an local ioniser for the work area, but its only needed in high risk areas (as said
before, heat, dust, humidity & if you have valve gear running at the same time with HT then...not
only diminishes the insulating properties of an air gap, but the agitation of the air can actually
be a source of static build up, even on the dust itself)

The last item I would mention is also important, validating your ESD precautions are working!, a
broken lead on a wrist strap or bad connection on the stud is just as big a risk (in fact more) than
not taking precautions in the first place. 

It is also not just a matter of checking ground, as I said above a direct GND connection should be
avoided, the discharge path should land around 1-10M so that is what you need to check. I have seen
plenty ESD wrist strap/plate/mat checking stuff on EBay for peanuts, probably surplus from a closing
down auction, well worth the investment.

Yeah, of course it is possible to get a kit built, working and for it to be reliable without all
this stuff or effort, but I can assure you these are the exceptions, not the rule, I have never seen
any bad results out of being careful.

Some links

http://www.mtechnologies.com/building/atoz.htm

http://www.esdsystems.com/techpage.asp

http://www.tkb-4u.com/articles/other/esd/Air_ionization/Air_ionization.php

http://66.102.9.104/search?q=cache:bYdNuRMujBIJ:assets.zarlink.com/AN/esd3.pdf+how+to+keep+ESD+under
+control&hl=en

http://www.esdjournal.com/techpapr/ryne/esdstds1.htm

http://www.sp.se/Electronics/services/esd/eng/info.htm

http://cr.pennwellnet.com/Articles/article_display.cfm?Section=Articles&ARTICLE_ID=67098&Publication
_ID=15

Enjoy the happy reading :-)

John (GM1BSG) 

> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net 
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of 
> Able2fly at aol.com
> Sent: Sunday, May 23, 2004 3:46 AM
> To: elecraft at mailman.qth.net
> Subject: [Elecraft] ESD precautions?
> 
> I've built a couple of solid state kits paying little or no 
> particular concern to ESD damage other than using a 3 wire 
> soldering unit. No problems so far, but I may be pushing my 
> luck. What would be the minimum preventive measures to be 
> taken when building something like the K2?  Is a grounded mat 
> desirable? 
> If so, would AC mains ground be the place to ground the mat 
> to? If there is a tutorial along these lines, I've yet to 
> come across it...
> 
> Thanks,
> Bill  K3UJ
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