Sorry, Neda, thought I made myself clear. Every time you walk across a
bare concrete floor, you raise dust, consisting of a variety of
chemicals, depending on the chemical composition of the concrete (yes,
it varies greatly from place to place). Most of these chemicals are
calcium salts, but also other cations, including a probable
not-negligible proportion of sodium. The anions are also varied,
including carbonates, sulfates and, above all, silicates. In humid
environments, concrete can even effloresce soluble salts. These all form
part of the dust you raise. Now, do you want such dust to fall on
electronics assemblies? I don't!
Brian
Neda Thrash wrote:
>
> Brian, please explain the chemical hazard, would the electronic assembly have to be in contact with the floor. How would it happen?
>
> <<< [log in to unmask] 6/12 1:19a >>>
> Concrete is porous, somewhat hygroscopic, pumps water up from subsoil,
> if it is on the ground floor, is a very ionic contaminant, as is the
> dust that comes off it every time a foot is placed thereon. It is
> therefore ESD-safe but is a chemical hazard to all electronic
> assemblies. It should be sealed and re-rendered ESD-safe, IMHO.
>
> Brian
>
> The Job Shop wrote:
> >
> > Hi All,
> > If you have a concrete floor, and are wearing your foot straps, is this
> > considered to be static safe?
> > Thank You
> > Jackie O'Roark
> > The Job Shop
> > 90 Brighton Ave.
> > Grover Beach, CA 93433
> > 805-481-1052
> > [log in to unmask]
> >
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