> Modern x-ray machines used to examine items, such as those at airport
> inspection stations use image intensifiers, and so the actual radiation
> level is extremely small. It would not erase a PIC.
>
> On the other hand, systems designed to irradiate items, such as those
> used to irradiate flies are specifically designed to deliver
> very high doseages in a short time. If this level of irradiation
> is employed, then film will be exposed, and it is possible
> that some erasure of PICs could be effected.


I agree.
But not in a controlled or necessarily useful manner alas.
Attempts have been made to erase OTP parts using radiation sources. I have
not heard of any successes. If there are any they are keeping it secret. I
understand that IC damage may occur at high enough radiation levels.

Radiation damages working ICs (hence "rad hard" parts) but I'm not sure of
the mechanism or what happens if there is no power applied.

Feeble attempt:
    I believe that in operation the radiation causes parasitic conduction
    across semiconductor layers that would not normally do so and can
    lead to immediate catastrophic failure.

Better attempt?
    Someone on this list will almost certainly have a better description
    of the actual mechanism.


        Russell McMahon

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