gEDA-user: solder stencil in drafting acetate

[Dave N6NZ <n6nz@xxxxxxxx>]

A while back we had a short discussion about doing cheap solder stencils 
in drafting acetate using a laser cutter.  As it turns out, I have 
access to a laser cutter at the TechShop http://www.techshop.ws/ so I 
gave it a try.

I took the postscript check plot for the paste layer, and converted it 
to .dxf using pstoedit (available under GPL). Then, I tweaked using QCAD 
(available under GPL).  Tweaks were simply removing the board outline 
and adding index holes for a fixture I might build some day.  Then, I 
laser cut the .dxf into Clear-Lay brand 5 mil drafting acetate.  Power 
levels were tweaky, and I think I should pre-shrink the pads to account 
for excess "meltage" at the edges, but I have successfully assembled two 
boards using my paste stencil, which I reflowed in a toaster oven. 
Smallest parts were 0603 and 0.8mm lead pitch TQFP.

Anyway, I declare the experiment a success.  Anybody that wants the 
cook-book details is welcome to them.

It would be nice if I could do this direct from the gerber for the paste 
layer.  I was wondering how hard it would be to tweak gerbv to output 
vectors for pad edges?  I'd be willing to hack in a .dxf exporter if I 
had a road-map and a little advice.

And, while I'm posting... I have a line on an old laser cutter that I 
might buy.  I'm wondering how many other pcb users would be interested 
in a plastic stencil cutting service?

-dave


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