On Tuesday, October 08, 2013 13:12:03 Matthias Johnson wrote:
> I could be wrong but I thought only the silver bags are conductive and not
> the pink bubble wrap bags found with most motherboards.

I've seen antistatic bags that are translucent blue, translucent pink, opaque 
black, translucent silver, opaque silver.  Good luck figuring out which type 
of bag has which kind of resistance/conductance.  :-P  An Ohm meter can only 
tell you point contact resistivity.

The problem with using nonconductive surfaces like cardboard is that then you 
can get static buildup, and again motherboards are ESD sensitive.  Walk across 
the rug, touch the device, zap...    Whenever I have a motherboard outside of 
the case, I like to wear a grounding strap (which _slowly_ drains charge off 
of you via a resistive wire with about 1 to 10 MOhm of resistance).

But of course powering up a motherboard on a conductive surface that doesn't 
_only_ touch the grounded screw connector area doesn't sound like a great idea 
either.  [I have occasionally done it, and never had a problem, but....]

I understand where Joe's coming from concerning grounding out the motherboard. 
I haven't seen this happen with motherboards specifically (a good number of 
the power connectors to the motherboard are supposed to be ground) but I 
_have_ seen some misdesigned (non-computer) PC boards that had a kind of 
"ground loop" through the board screws that shouldn't have been there.  
Another interesting thing that can happen is a crossover of grounds like a 
misconnection between "signal ground" and "power ground" on RF boards, and 
that can occasionally cause some interesting problems (RF on the power, 
switching DC power noice on the RF, etc).

  -- Chris

--
Chris Knadle
[email protected]

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