Homebrew PCBs

There's two minor problems with that workflow from my experience:

- I've found that drilling through the paint tends to drive it into the hole, and getting it out is a pain.  If you don't/can't the paint out, soldering the thru-hole lead then ends up "washing" the paint out of the hole with the molten and pollutes the solder joint.

- I'd be concerned, unwarranted or not, that by drilling through the mask, you'd risk a little undercutting (during etch) around the hole penetration.  Probably a non-issue if you've got rings/pads of any size around the drill hole.

As far as cutting being your biggest problem -- we just shear ours.  It's kind of Neanderthal, but it works well enough for us.

It seems like the paint would be a reasonable solder mask, and probably an even better surface to print on with, say, an open-faced inkjet.

Our results with alignment are adequate as it stands.  Having a jig  with pegs and pre-drilled/marked boards, all going into the laser cutter sounds like a lot more effort than reward.  If I were trying to push the process down to a primo 8mil/8mil one, then it'd probably be necessary though.  As it is now, it would seem to at least double our workflow effort.

-e

--- In Homebrew_PCBs@yahoogroups.com, mlerman@... wrote:
>
> Two sided alignment has been solved by the people who do cnc routing of boards. They use aligmnet pins (or optical markings) on the Y axis and software to do all the work of alignment and isolating the traces. I think Eagle has a ULP for this, too. I have a cnc board router, and the biggest problem by far is the cutting - you have to change bits, they break, etc. So If I could use a laser to do the isolation I could:
> 
> paint the board
> burn isolation traces with the laser on both sides
> drill the boad on the cnc
> etch the board
> put it back on the cnc to burn away over the pads, leaving the paint as a solder mask.