Hi Steve,
To see what you are dealing with, turn on your oscilloscope, set its sweep
speed to 10ms/dividion, set its vertical deflection to 0.5 V/division, and
with one hand, grab the tip of your scope probe.
That signal on your screen is real, and has enough current to drive a 10 meg
to ground load. Now, imagine what that signal would be if your load
was 100 meg, or 1000 meg to ground.
Oh, and it doesn't matter what kind of lighting you are using, this is stray
coupling to the power line. If you use mains electricity, it is there.
-Chuck Harris
Steve wrote:
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Thanks Mike and others for the advice, it's most helpful and educational.
I didn't realize that fluorescent lighting could be a problem. In any event, I'm not using that kind of lighting.
I will take a look at 3M and other mats, both for the floor and the bench top.
73,
Steve K8JQ
Mike wrote:
have been through this a couple of times in last 20 years,
a. Using a static mat from 3M or one of the top companies that supply
to HP and others is the best recommendation, those mats allow
static discharge at the best rate. Dont use an aluminium sheet to ground
as some people have tried.
b. If you have overhead fluoros then might need to reduce the mats 1M to 100K,
in my case the 1M meant the mat wasnt draining the field from the fluoro and
we blew many mosfet gates (the ones without protection zeners). If you are not
going to be handling anything without protection zeners then dont bother.
c. Have a region of interface between the static mat region and where you walk from
so some static can dissipate before you get to the mat. Like a 3m area which
is floor treated, floor mat is ideal but I find that carpet is ok if its treated twice a year with some spray on static treatment.
d. If you are handling a lot of very sensitive devices in most other places in the lab
where they might be stored but not worked on then a static controlled fan might
be helpful, cant recall the name but it has a ion source either mildly radioactive
or a power operated type. I dont use one myself but depends what you are handling,
others might comment on that.
cheers
mike
At 11:50 AM 3/12/06, you wrote:
There was a discussion regarding workbenches on this reflector back in October and I'd like to ask for some follow up advice.
I'm planning to replace an old workbench. Is there a top I can put on my new workbench that is ESD safe? Right now I have an ESD mat that I place on the workbench surface when appropriate.
Inasmuch as I'm going to be more or less starting from scratch, I thought I'd at least ask the question about an ESD-safe work surface.
Thoughts or advice out there?
Thanks.
Steve K8JQ
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