Andreas Pirner wrote:
> Winsor Crosby wrote:
> Origin of problems are Sony CCD sensors made between 10/2002
> and 03/2004. At that time frame is said to be critical by
> Sony. A reason given for the problems are wires getting
> loose, wires from/to the CCD sensor.
>
> Sony had experimented with the bonding chemicals to increase
> output rate. Some jodine related substance creates most
> troubles. It evaporates and corroded the wires. The
> manufacturing process is altered since and thought to be
> corrected now.
------------------------------------------
Reminds me of IBM's "silver migration" problem of the early 70's. IBM's
chips were ultra-sonically bonded to a ceramic substrate that contained
circuit lines printed on the substrate with a conductive paste made with
powdered silver. For reasons never well understood the parts began to
fail in the field in large numbers. It was known that the failure was
caused by silver particles physically migrating away from electrical
contact with the substrate's contact pads but no one had been able to
figure out why. Especially perplexing was that the same basic
manufacturing processs had been used successfully for almost 10 years
prior to the problem showing up. Studies showed that parts made with
gold or palladium circuit pastes did not suffer from the problem. Since
no one knew how else to solve it and system reliability in the field was
beginning to seriously deteriorate there were major plans put in place
to repopulate all existing systems in the field with new parts using
gold only. The cost would have been in the many billions of dollars...
back in the days when a billion was a big number.
Eventually, QC tracking data and a persistent engineer figured out the
problem. The substrates in question were manufactured in both East
Fishkill, New York and in Manassas, Virginia. QC tracking data finally
showed that only parts manufactured in Manassas were failing. At the
time the Manassas facility was fairly new but the equipment, machine
operators and management were largely transplants from East Fishkill.
So, despite being in a different place the equipment and processes
should have been the same and with equal quality.
Now comes the real sleuthing. The QC tracking data eventually showed
that parts failure only occurred with parts made in a narrow time window
in both morning and afternoon. What happened during these two time
windows was that a freight train would pass in the morning on a nearby
spur line to drop off a couple of freight cars a few miles away and
would return in the afternoon to pick them up. The vibration from the
passing train caused years of accumulated contaminants in the exhaust
stacks of the curing ovens to shake loose and fall as fine soot onto the
parts as they were moving through the ovens. The soot caused a chemical
reaction with the circuit line paste that, a year or so later, would
cause physical migration of the silver particles away from the point of
electrical contact. Case solved. Clean the stacks. Lesson learned.
Extensive detail in manufacturing quality control records may not be
overkill.
Some had speculated that the original cause of the contamination was the
machine operators choosing to bake their lunch time pizzas in the curing
ovens... but I don't think that was ever proven :-)
Sorry, for the long OT story but I love to tell it and rarely get the
chance.
Chuck Norcutt
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