Brad Marshall wrote:

> Hello,
> I have a person here that wants a 50mil X 250mil rectangle plated
> through hole.  I am having trouble figuring out the best way to do this
> with Protel so that the board house will know what I want.  Any
> suggestion/comments are appreciated.

You'd better contact your board house before going any further.  This
is a procedure they generally cannot do with a CNC drilling machine.
They would have to do it as an additional step with a router, and this
may foul up their work flow such that they may refuse to do it, or quote a
high charge.  There are questions of cleanliness, etc. that may make
them extremely reluctant to do routing on a laminated multilayer before
the hole plating.

If the hole can be unplated, but have copper surrounding the hole that
is connected through by via holes surrounding the rectangular hole,
it will not incur any special handling, and any board house will do
it without problem.  I'm guessing this is a component mounting tab,
and they want it soldered.  Hand soldering the tab to the bottom foil
should be no problem.  Depending on the dimensions of the tab
(especially thickness and heat sinking capacity) it may not wave solder
real well in an unplated hole - maybe this is the concern.

Protel has no method of specifying non-round holes.  Pads can be
rectangular,
but a hole is just 'n' diameter.  The only way to specify it would be to
have
a hole of some size unique to the entire board, like 1 mil, maybe.  Then,
tell them the callout for T03 (or whatever) is actually your 50 x 250 mil
rectangular hole, and the orientation is with the long side parallel to the

X (or Y) axis.  Note, these holes will NOT be rectangular, either, unless
punched.  Note, G10, FR4, etc. glass fiber panels generally can't be
punched easily, and there is considerable damage to the panel around the
punched hole.  A routed hole will have some minimum radius in the
corners.

Jon



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