[Elecraft] ESD precautions?(the nitty gritty)

[John A. Ross [RSDTV]]

> -----Original Message-----
> From: Able2fly at aol.com [mailto:Able2fly at aol.com] 
> Sent: Monday, May 24, 2004 12:13 AM
> To: john at rsdtv.com
> Cc: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] ESD precautions?(the nitty gritty)
> 
> John, thanks,
>  
> What you say makes more sense to me than anything I've heard 
> in a while. We don't want sparks jumping, so we want 
> everything relating to our work project at the same potential.
> So we "ground" everything to the mat. Ourselves, our tools, 
> soldering equipment, work-in-progress, components, wrist 
> band. Whether the mat is "grounded" to mother earth or to the 
> mains "u" ground pin, or wherever, is of minor concern as 
> long as the "works" are all brought to the same ES potential. 
>  (Correct me if I'm wrong.) Granted, we MAY be practicing a 
> bit of overkill, but why not? There's nothing difficult or 
> expensive involved and think of the peace of mind ;-)

Bill

Please take 'to GND' as being a relatively high impedance path, most ESD equipments 'GND' points are
via 1M resistor or higher to 'dampen' any discharge.

But you got the general idea on the PD thing, but any charge present needs to go, its not enough to
work with a high charge level of same PD. Ideally all items to come under contact should be
discharged first, to the same point.

I would not apply the same rules as cross bonding feeder cables or equipment to a true GND as the
purpose there is quite different. Neal, no comments? :-)

Also it would be easy to take my comments and go OTT with precautions, not everyone has the space to
do it at home, sometimes I forget that, I have not done true 'home' construction for so long as I
have full use of the facilities at work whenever I want :-) and it is a well controlled environment
http://www.rsd.tv/design.jpg , the pics 3yrs out of date now but my lab area is to the left of that
shot (you think an engineers desk should ever be that tidy, ha! ), the photographer used that angle
on purpose as my end is always a mess and I am stubborn about clearing it up just to please other
people (no mess, no work in progress as they say). 

But I started out life with a workspace (including rigs) of 5ft x 9ft at my parents home, many years
ago now, which was previously a coal store, in fact I practically lived in it, now I just have a
bigger store :-)

But the invisible ESD monster is everywhere..........

John (GM1BSG)

> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> john at rsdtv.com writes:
> 
> 	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_io
> nization.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) 
> 
>