Hi,

Thought I could add my 2 cents.

We had seen a case where one of our layout practices were causing some
similar problems. In my department it was decided to leave the
soldermask between the pads of the components to prevent a reflow
between the pads. This dry-film when applied was taller (from the board
surface) than the pad metal, which worked to suspend the center of the
component above the two ends if hand soldered. Essentially keeping the
component under a constant state of flex while the board were temp
cycled caused some fairly significant leakage issues (and micro-cracking
of the component).

This practice also created a void between the component, the pad and the
soldermask where flux would get caught when the boards were cleaned.
Over time the flux would harden creating a nice moment arm against the
component if the board was flexed. In the particular environment I
design for, our boards see a bit of flex in normal use and some
components popped off like popcorn, imagine the stresses on the ones
that didn't.

This may seem to be a newbie response, and I apologize if it was a waste
of time, but my personal learning in this experience was significant.
Talk to your PCB manufacturing/assembly shop.

Regards,

Brett
--
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Brett Grossman                              __          ___
Intel Test Tooling Operations    __        /\ \__      /\_ \
Phone: 408-765-2619             /\_\    ___\ \ ,_\     \//\ \
Fax:   408-765-2518             \/\ \ /' _ `\ \ \/    __ \ \ \
email: [log in to unmask] \ \ \/\ \/\ \ \ \_ /'__`\\_\ \_
                                  \ \_\ \_\ \_\ \__/\  __//\____\
                                   \/_/\/_/\/_/\/__\ \____\/____/
The views expressed are my own.                     \/____/
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