A number of shorted probes were found, all with tin whiskers.
The depth of the barrel made it very difficult to get good
illumination of the whiskers. Eventually,
a probe was cut apart and put in the scanning electron microscope (SEM)
for measuring dimensions.
Energy dispersive X-ray Spectroscopy (EDS) was also used to verify that
the terminal surface finish
was tin plate.
It appears that for at least one box of scope probes,
2004 was a vintage year for growing tin whiskers.
Whiskers were observed that grew straight across the gap,
but they could not be illuminated well enough for a good picture
using optical microscopy. The
engineer owner of the probes salvaged them by “routing out the
whiskers” with the end of a wire.
Acknowledgment to Mr. Bill Rollins for contributing this anecdote