> On Dec 22, 2017, at 14:08 , rkr...@johngalt.biz wrote:
> 
> 
> 
> On 12/22/2017 12:16 PM, G4GNX wrote:
>> Firstly, you absolutely MUST use an anti-static mat, suitably connected to 
>> ground and an anti-static wrist strap. Whilst you might "get away with it" 
>> without those items, you may cause unseen damage and you won't know until it 
>> breaks down. I know the manuals state that you can "touch a metal object", 
>> but that's very hit and miss.
> 
> I'm going to respectfully disagree.  The problem is not the static or the 
> ground, the problem is when you have a differential voltage between items.

Yes, and/or perhaps you add some charge that you brought to the party.

> If you always maintain a forearm on the frame of your device and handle 
> things carefully while maintaining contact with the frame, you will all be at 
> the same electrical potential.  Be sure to be in contact with the frame when 
> opening anti-static bags, too. Hold boards by the edges, don't finger the 
> gold contacts, and don't touch components if you don't have to.

Possible, but hard to accomplish in some situations. Ambient conditions (humid 
vs arid) can make a big contribution to the potential for electrostatic 
discharge.

> This technique has worked for me for years.

I assume that means you have never seen the correlation between “it was 
working, I did something to it, there was a spark, and now it does not work”.  
This observation is common.

Damage form electrostatic discharge is often incremental - the damaged part 
keeps “working” but sometimes not as well as it used to - this falls int he 
category of “incremental”  static damage and can degrade the performance of the 
device, part, circuit, or system. Sometimes you have measure the performance 
carefully to “see” the damage - or take the top off the part and use an SEM.  I 
changed the way I think about this, and work on electronics, based on a 
collection of photos that an analog engineer I worked with in the 80’s showed 
me.

In a simplistic example, a small discharge can blow a gate in a 24 bit A/D 
converter which then fails to correctly report the result, or an opamp to loose 
gain or add noise, often in small steps.


>  I don't do sensitive work often, but I never seem to have all the 
> 'anti-static' stuff when I need it.


That is simply a matter of being prepared…..  My approach is similar to the one 
I use for trauma kits: scatter them around in the likely places - as someone 
else said, it’s cheap insurance.

> 
> The only danger is if you get carried away

or distracted

> and lift that arm.

YMWV,
-Dale
KB1ZKD

> 
> 73
> 
> Ray
> KK4WPB
> 
> Molon labe
> 
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