27 Jan
2006
27 Jan
'06
2:10 a.m.
At 09:24 PM 1/26/06 -0700, you wrote:
On 1/24/06, Chris M <chrism3667 at yahoo.com> wrote:
Not that I ever heard of. A friend of mine used to failure analysis for
an aerospace contractor and he routine cut ICs apart to examine and test
them. Many of them were examined for things like ESD, overheating and
chemical exposure damage that didn't cause immediate failures but could do
damage and cause failures later. The ICs frequently passed operational test
even after they were cut open.
Also several months ago someone on this list mentioned that he worked in
a shop that had a wire bonding machine and he frequently took "failed" ICs
and replaced the failed bond wire and keep on using them. He said that some
ICs had had the bond wires replaced numerous times.
I don't know what they do to the package,
I've been dying to ask this question. Can
you
actually learn something (hopefully a whole lot!)
about a chip if you actually did this??? What if there
was some old chip for which there is no documentation.
If, given the availability of the proper equipment
(surface grinder?), you were able to take off say
.0001" of material at a time, or thereabouts ;), would
you have the ability to photograph it, and have
something in the way of a working schematic?
Aren't there chips (i.e. crypto) that are designed to be destroyed
if they are disassembled? but if I had an IC with an EPROM containing my crypto
keys, I'd want
the chip to self-destruct during an attempt to pry open the package
:).
You'd probaly better with battery backed RAM that would lose it power
(and contents) when it was removed from the circuit. Or else redisign and
use a PAL or some form or programmable logic that has a security fuse to
prevent it from being read.
Joe
--
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