ESD, 2nd mail for ESD, was : RE: [sdiy] midi optocoupler isolation voltage?

[Scott Stites]

Back when my place of employment was adopting a rigorous ESD policy, we were
testing everything.  We had these little hand held electrostatic field detectors
that could read the ESD charge on a given object in reference to a reading we
would take off of our conductive mats (which are tied to ground).  

We found that a significant source of charge originated from the oscilloscope
CRT's on our benches.  We took some metal mesh, the same cloth-like stuff we use
to keep EMI/RFI emissions from leaking through the displays on our products, and
covered the scope displays with that, placing it over the outside of the lens
with the ends tucked inside the faceplate of the scope.  IIRC, mounting it in the
way we did put it in contact with chassis ground of the scopes through the screws
that held the oscope faceplates on.  It dramatically decreased the ESD readings
emanating from the oscilloscopes, pleased our static police greatly, and there
was much rejoicing.  

Of course, a computer CRT is quite a bit larger than an oscope CRT, so covering
it with mesh would require a lot of the stuff.  Our gyrations with the oscopes
may wander into the range of overkill (if there is such a thing when ESD is
concerned in a manufacturing/service environment), considering the fact that our
oscopes were relatively distant from the conductive mat where the sensitive
devices are being manipulated.  The scopes are placed above the bench, within
arm's reach, but is still quite an air gap.  Also, we use ionizers and, of
course, wrist-straps and conductive jackets.  But it's a thought....and YMMV.

Scott


On Wed, 12 Mar 2003, Ingo Debus wrote:

> Czech Martin wrote:
>  > Some CRTs will easily intruduce a large
>  > E-field that can lead to static, too. Especially when switching
>  > on or off. Keep away from that, too.
> 
> Nice suggestion, but I wonder how can I keep off my computer monitor
> during microcontroller program debugging?
> Hm, perhaps time to get a TFT monitor...
> 
> Ingo

________________________________________________
PeoplePC:  It's for people. And it's just smart. 
http://www.peoplepc.com