Homebrew PCBs

Very interesting. Assuming your limiting factor is the beam width, 
can you focus the laser to a smaller width? On ebay I see CO2 lasers 
for engraving at $1600 with shipping that might do.
Mark


At 09:00 AM 12/29/2010, you wrote:
>We've been using the paint method to do boards for a few months now, 
>and it's been working pretty well.  If you need top-notch detail, 
>then you need to go with a photoresist solution.  10mil/10mil is 
>pretty easy to do repeatably.
>
>The key thing to remember that the laser is about 8mil wide.  This 
>will affect the width of the traces and isolation that you lay out, 
>because you'd end up with less and more, respectively.
>
>We have noticed the re-adhesion behavior mentioned below, but if you 
>reduce the paint to the minimum needed for coverage, the amount of 
>airborne burnt-off paint will be correspondingly reduced.  Burning 
>from the far side of the board probably couldn't hurt.  We clean 
>lasered boards gently with IPA and a cotton ball before etching.
>
>We've gone from bare copper clad board to etched-undrilled in about 
>30 minutes with fresh etchant (FeCl).  Assuming that you have access 
>to a laser printer, the ease+cost can't be beat (you might be able 
>to do cheaper by hand-drawing or plotting with a resist pen 
>though).  But you won't be running two traces in between 
>0.1"-centered holes either, so there's still a place for photoresist 
>in the world.
>
>We haven't done any soldermasking, but if you find something that 
>works well for you, let us all know.
>
>-eric
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