I was reviewing a new design and found the mounting holes have plated barrels.

In my past, I have always steered Design away from plating the barrels of PWB holes used for mounting holes (and torque).

Far back in my memory, I remember experiments I had run which revealed that the HASL solder on the mounting hole annular ring allowed solder creep making the fasteners come loose over time.  I also seem to remember something about not wanting to put a barrel in compression.  This is a double sided board mounted to a copper plate and the entire assembly is tin lead plated and then fused.  On a multilayer board, the argument is easily made to not compress the internal layers.

I am looking for something in the standards which might provide some direction against this type of design.

The only stated reason from the mechanical designer was increased thermal dissipation, for which my argument is that the fastener provides much more capacity for transfer than does the barrel wall.

Am I being too conservative?

Phil



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