cctech Digest, Vol 29, Issue 59

[Terry King]

>Subject: Re: grinding down chips was Re: QX10 graphics board
>
> > I don't know about grinding, but the guy at MIT who figured out the Xbox
> > innards did something of the sort (regardless, it's a great read):
>A guy I went to school with does this for Motorola. He gets chips back
>that are failing in the field and dissects them to find out what went
>wrong.
>I think the actual process involves shaving rather than grinding.


In the FA (Failure Analysis) lab at IBM, the "De-layering" process was 
complex, with different
chemical and mechanical approaches or combinations, on different types 
of  layers.

  Often, the objective was to find the actual site of a failure, and expose 
the layer or layers involved, to try to find the actual physical reason for 
the electrical or functional failure.

Sometimes this got complex, such as removing a minute particle of 
contamination, and putting it thru a Mass Spectrometer to try to find out 
what the heck it was.  They had "Signatures" for various contaminants, 
including, as I recall, cosmetics, human epithelial cells, dust mites, 
various fabric fibres, etc.

Sometimes, they tried to keep the lower layers in working 
condition!  Partially delayered chips were sometimes operated, in a vacuum, 
with a low-power scanning electron microscope as a probe.  It was possible 
to extract waveforms, or scan multiple points to create a logic-analyzer 
type display.  And the graphics were neat, with voltages from 0 to 5 volts 
displayed as shades of gray.

As a test system designer, I thought this stuff was way cool, and I once 
proposed building a complete test system that included and drove the 
scanning electron microscope, and produced graphics displays in real 
time.  I estimated only $500,000 (including the software!).  It got shot 
down.  5 to 7 years later they spent over a million on a Siemens (I think) 
system that did pretty much the same thing.  Oh well.


Regards, Terry King  ...On The Mediterranean in Carthage, Tunisia
terry at terryking.us