John Payson wrote:
>
> | You can
> | speed up erasure time by placing the chip erasure window
> | even closer to the UV lamp. I usually use pieces of that
> | black or pink anti-static carrier foam to hold the chips
> | where I want them to be.
>
> I would suggest the black material over the pink; the black
> material is slightly conductive, ensuring that any static
> charge on any part of its surface will slowly spread out over
> the entire thing; thus it's impossible for one spot on the
> foam to hold a charge relative to the rest of it.  The pink
> stuff works by refusing to easily accept or give up electrons
> on its surface (so it won't take a charge in the first place).
> In many situations this is just as good, but strong UV can
> cause ionisation (i.e. electrostatic buildup) in many materials
> including those inside the PIC and it's probably a good idea to
> give those ions a safe path lest they find an unsafe one (e.g.
> by breaking down the PIC's dielectric).

  Replace the foam periodically, too (The UV "Rots" it in time.)  I've
seen gang "Tray" type erasers with just crumbs left, in production
environments where they had a gang programmer & were constantly erasing
scads of 27256 EPRoms.  (Most of Us:  Every couple years;  Them:
Monthly.  They ran the eraser 15 hours a day or so!)  Still have 27C256Q
Eproms left from there <G>

  Anyone ever tried sponge metal for this job?  I've wondered if it'd
work (Pricey stuff last I priced it, though.  Should last forever OTOH.)

  Mark, mwillis@nwlink.com