On 2012-11-04, Michael A. Terrell wrote:

"DoN. Nichols" wrote:

On 2012-11-03, Michael A. Terrell wrote:

Not with lead free solder. Tin whiskers can grow a lot faster than
four years.

Have a look at the paper 2011-kostic-Pb-free.pdf to be found at
http://nepp.nasa.gove/WHISKER/reference/tech_papers/2011-kostic-Pb-free.pdf

[ ... ]

This also explains the "unintended acceleration" problem in cars
with computers monitoring the accelerator position.

In particular -- look at page 57 through 59 to see that documented.

The next page documents potential failures of pacemakers caused
by the whiskers.

[ ... ]

Don't you find it interesting that military, aerospace & medical are
exempt from using lead free solder?

Personally -- I find it quite reassuring. (Except for that
batch of pacemakers which had to be recalled in the medical category.
:-) The problem is that components without lead free solder are getting
harder and harder to find -- unless you purchase in really massive
quantities and thus have leverage over the manufacturer.

But I also consider the whiskers in the speed pot in the Toyotas
(and likely other "fly by wire" cars as well) can be similarly
life-threatening. Not just to the driver of the car involved and his
passengers, but to others sharing the road.

I'm glad that the Nissan Cube which is my most recent auto --
and my only "fly by wire" one -- has a way to force the engine to shut
down at speed. Either hold the "start" button down for over three
seconds, or poke it several time in quick succession. I hope that this
will get past the usual whisker induced catatonia. At least whiskers
across the "start" switch should force a shutdown. :-)

And yes -- I *did* experience a floor-mat induced runaway
accelerator -- in a Datsun 240Z that a co-worker was buying and which
had problems with the SU carbs, which I was familiar with from the MGAs
which I owned and drove. At least that had both a clutch (to allow me
to uncouple the engine a bit) and a true ignition switch, to allow me to
shut down the engine. :-)

Enjoy,
DoN.

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