Jim --

> The parts I'm talking about here are the "SEM" series connectors from
> Samtec.

This is a board-to-board connector, mating with the "TEM" connector series.
When mated, the TEM wraps completely around the SEM. Is it possible that
differential expansion/contraction between the two boards is simply applyin=
g
too much force to the body of the SEM during the temperature cycling?

When using direct board-to-board connectors, it is generally a good idea to
use them between boards that are of a similar size, mounted parallel to eac=
h
other using the same anchor points. This minimizes differential movement.

If this is not possible, then the next best alternative is to make sure the
boards are solidly anchored to each other (or to the chassis) near where th=
e
connector is, and thermal expansion/contraction is allowed to occur only at
the far edge of each board.

-- Dave Tweed
--=20
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