Re: gEDA-user: Tab holes in PCB

[joeft <joeft@xxxxxxxxxxxxx>]

Peter Clifton wrote:
> 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.

That's it - give them a "layer" or mechanical drawing that shows how you 
want the slot dimensioned.  Show them the largest radius you can deal 
with and let them pick the tool (cutter) that they like to use.

If you can get by with either:
1) a round hole that is plated
   or
2) slot that is not plated
it would be much easier than asking for a slot that is plated.  Routing 
before plating is an extra or non-standard process step for many shops. 
  That said, you can surely find someone to do it - at a price.

Peter is correct.  Talk to them up front to find out what's easy and how 
do document it unambiguously.

Joe T

> 
> 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,
> 


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