Re: gEDA-user: Tab holes in PCB

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Fri, 2009-02-20 at 16:20 -0500, Rob Butts wrote:
> I have a pcb mounted power jack with rectangular bendable tabs.  Since
>    I'm going to try to make this pcb at home I'd like to put these holes
>    in the layout as they are and not round holes with the diameter
>    equaling the widest part of the tab.  Can I make a rectangular hole in
>    pcb and if so how?  How would the Pin statement look?
>    Thanks

I don't think you can. Lets look at how this "might" be done
industrially:

You're no longer talking about a drill hole in the "excellon" sense of
the word. You'd be looking at a custom manufacturing step involving a
router, similar to how they cut the outline of a finished board.. only
this processing step would be done before the through-hole plating.

I believe you'd have to describe this step using a mechanical layer,
along with written instructions to the board manufacturer what that
layer means. It would almost certainly not look like a traditional via
in PCB.

I'm not sure how the vendor would want the slot described, it would be
something you'd have to agree with them up front.

It might be a line / other primitives defining the geometry to be cut
away. It might be a center-line for the tool path, either accounting
for / not accounting for the cutter diameter.

I don't know how other CAD software treats such mechanical layers, how
the slot routing would be rendered. (Would it look like an elongated
via, for example).


Best wishes,

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)



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