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From: Robert Baer on 27 Apr 2010 04:46
John Larkin wrote:
> On Mon, 26 Apr 2010 00:44:13 -0700, Robert Baer
> <robertbaer(a)localnet.com> wrote:
>
>> GreenXenon wrote:
>>> On Apr 15, 5:31 pm, whit3rd <whit...(a)gmail.com> wrote in
>>> http://groups.google.com/group/sci.electronics.design/msg/afed810b124c3b77
>>> :
>>>
>>>
>>>> On Apr 15, 2:15 pm, GreenXenon <glucege...(a)gmail.com> wrote:
>>>>
>>>
>>>>> Can similar data recovery be performed on volatile RAM chips even
>>>>> after the power is offed.
>>>
>>>> Similar, no. Recovery, yes. The volatility has a time decay constant
>>>> of a second or so, and it takes a long, temperature-dependent, delay
>>>> after power-off to thermalize the information to nonexistence.
>>>
>>> Let's say that after the power supply is cut-off from the volatile RAM
>>> chip, the RAM chip is heated to the hottest it can get without
>>> suffering any physical damage. Will this speed up the rate at which
>>> data is lost? What is the maximum physically-safe temperature to erase
>>> all info? What would be the best way of heating the chips?
>> Nominal MIL-spec temp range is -55C to +125C so one can safely use
>> +125C for this operation.
>> That said, most semiconductors easily tolerate 150C.
>> Remember, ions, static charges, and chemical reactions speed up by a
>> factor of two for every 10C increase in temperature.
>
> Ions speed up? Static charges? Explain?
>
> John
>
>
>
Oh yes! Put a charge in a CMOS device or even take those trapped
under / inside and measure the capacitance as a function of voltage.
Bake at 250 with one polarity present then re-measure after cooling
(voltage present while cooling always), bake with opposite polarity
present then re-measure after cooling (voltage present while cooling
always), bake with a short and re-measure.
With the data, one can calculate amount of positive charges and
amount of negative charges trapped.
Over sufficient time and temp, a goodly amount of those charges do
dissipate.
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