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[OM] Re: CF longevity, was: Re: Film vs. Analog - interesting read

Subject: [OM] Re: CF longevity, was: Re: Film vs. Analog - interesting read
From: Tim Hughes <timhughes@xxxxxxxx>
Date: Thu, 14 Sep 2006 12:29:51 -0700 (PDT)
I don't think it was "cosmic ray" protection, I think it might have been alpha 
particles from the
universally used special type of epoxy encapsulation, and so could be screened 
by a suitable thin
coating. Unfortunately it is a very long time since I read that, and my "analog 
memory" is hazy
having been hit by too many particles in the meantime.  I was just verfiying 
Chuck's memory there
was some issue related to the smaller and smaller amounts of stored charge. I 
believe the
Norden-Fowler tunneling mechanism used for programming of flash memory, damages 
the extremely thin
oxides used because of the extremely high voltage gradients that must be used. 
That is why there
is a limiting cycle life wear out mechanism.
Tim Hughes

--- keith_w <keith_w@xxxxxxxxxxxxxx> wrote:

> Tim Hughes wrote:
> > I seem to remember reading the normal memory chips suffer from ionizing 
> > radiation hits,
> (because
> > the number of electrons stored has got to be so small), but they now 
> > encapsulate/cover the
> chip
> > surface to minimise the effect. 
> > 
> > tim Hughes
> 
> What are they going to cover the chip with that will stop cosmic or gamma 
> rays 
> from zinging right on thru?
> 
> keith whaley
> 
> >> that too.  But I do not know if those bits will eventually fade off into 
> >> the void sitting in the closet or if they're subject to flipping from 
> >> cosmic rays.
> >>
> >> I do know that cosmic rays were a worry to at least one of IBM's memory 
> >> engineers when chip density hit 64K bits about 30 years ago.  But that 
> >> problem was obviouly solved or else maybe didn't exist in the first place.
> >>
> >> Chuck Norcutt
> 
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