[log in to unmask] wrote:

In fact, at one company we were required to tie the swaged hole to vias 
which had thermal relief connections to planes, instead of having a thermal 
on the swaged hole itself.


	IPC-D-275 states that no plated through hole should be put under
	compression, I believe all would agree this extends to the mechanical
	stress of swaging.

	We see alot of mechanical situations that call for plated mounting
	holes to be connected, usually to a chassis or system ground.  I
	tend to believe the mechanical engineers are not aware of the stress
	limitations when they call for this.  In any case, the proper way
	to bring electrical connection to a mechanical hole is with a pad
	on the appropriate outer layer(s) and a trace to one or many vias.

	In some cases we are forced by the engineering netlist to put a
	plane connection directly on the mechanical hole.  Since the stresses
	can cause the PTH contact to fail we add the trace and via also.

	(only when the connection is important... !)

	Cheers,

        Jeff Seeger                             Applied CAD Knowledge Inc
        Chief Technical Officer                      Tyngsboro, MA  01879
        [log in to unmask]                               508 649 9800

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