Question on ESD mats....

[geronimo]

Recently my co. got on the ESD bandwagon, they had some technicians
come in and install a ground point on our test bench, and they gave us
two sets of ESD mats and grounding straps. I think they are 3M brand.
The mats have a round metal snap to attach to the workbench ground. I
checked the resistance of one of these new mats with a Fluke DM 77. It
was a long time ago, and I don't remember what the reading was exactly
from the attaching snap contact to the surface of the mat, but I
remember it was many megohms, if not infinite. I thought at first
that this cannot function to protect against static charges. But
possibly it is supposed to be up in the megohm range? I understand
that to be a dead short to ground would be just as bad. There is
supposed to be SOME resistance....but how much?

 

[Jim Yanik]

geronimo <Jamesw@grandecom.net> wrote in
news:vj9mu25gh8fkutsle7sv10s7em058n6nfa@4ax.com:

Recently my co. got on the ESD bandwagon, they had some technicians
come in and install a ground point on our test bench, and they gave us
two sets of ESD mats and grounding straps.

wrist straps? One bench mat,one floor mat?

I think they are 3M brand.
The mats have a round metal snap to attach to the workbench ground. I
checked the resistance of one of these new mats with a Fluke DM 77. It
was a long time ago, and I don't remember what the reading was exactly
from the attaching snap contact to the surface of the mat, but I
remember it was many megohms, if not infinite. I thought at first
that this cannot function to protect against static charges. But
possibly it is supposed to be up in the megohm range? I understand
that to be a dead short to ground would be just as bad. There is
supposed to be SOME resistance....but how much?

IIRC,greater than 500K R,less than 5 megR.
the 3M mats are measured using specified weights with specified contact
area,spaced a specified distance apart.


At TEK,we also had floor mats and had to wear heel straps on our shoes,and
every morning had to TEST the wrist and heel straps on a 3M tester.The
wrist straps DO wear out,and you need to test them to insure they are good.

And we also wore anti-static lab coats.

--
Jim Yanik
jyanik
at
kua.net