A Design perspective on non-functional pads:

	Submitting fab data to "any" fab house on behalf of a large 
	design customer base, we had a tug-of-war from fab house to
	fab house regarding these pads, sometimes on the same product
	being multiply-sourced.

	Sometimes the customer would have an opinion, too.

	Customers have told us to remove the pads and use the routing
	space, usually on a .050x.000 pitch PTH connector.  They don't
	have to worry about primary drill @ DTP, compensation/registration,
	or those other nasty little details.  So we've been heading this
	argument off for a while.

	We've been asked to remove them on outer layers, also; this
	caused cleaning problems in fab and assembly processes.

	Experience showed that non-functional-pads were alot easier
	to remove than to put back.  An ad-hoc survey of CAM software
	showed that most systems could remove them in a few keystrokes.

	Our answer evolved to leaving the non-functional cu in place and
	allowing addition/removal at the fabrication house's discretion.
	They are the entities responsible for producing non-warped PWB's
	that survive normal thermal cycling, without shorts or poor yield.
	We can only try to help foster these goals by not boxing them in.
	<applying good design practice helps *a little*>  Only one fab-
	rication house has insisted the pads be removed.

	We also found use in keeping the non-functionals in place for drc,
	both normal platform drc (some CAD systems don't look at details
	like drill size) and our own post-gerber checks.

	Good luck!

	Jeff Seeger				Applied CAD Knowledge Inc
	Chief Technical Offficer		      Tyngsboro, MA 01879
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