Homebrew PCBs

On Sat, 02 Dec 2006 17:47:01 +0100, DJ Delorie <dj@...> wrote:

> My next project is probably going to require a solder paste stencil.
> So, I've been pondering what to do.  I could buy one, but that's
> expensive, adds delays, and isn't as much fun as doing it myself ;-)
> I've tried drilling a transparency sheet (plastic) but the holes were
> very rough.  Plus, I don't have drills small enough for the SMD pads
> I'll be using (11 mils wide).  So I thought of etched brass, since the
> toner transfer kits say they can be used for that.
> After a little research and some thought, there seem to be two
> common techniques:
> 1. TT on one side, paint the other side, etch in FeCl or H2O2, clean.
> 2. TT on both sides for faster etching and cleaner edges.
> But I thought of a third, based on how pcb-pool makes PCBs.  I have no
> idea if this would work, but it goes like this:
> * TT on both sides, with toner *only* where you want paste.
>   I.e. little dots of toner all over the place.
> * Electroplate some tin or other metal onto the sheet.
> * Remove the toner, leaving exposed brass where the paste goes.
> * Etch.
> Not sure if this has any practical advantages over original option #2,
> though, and it's probably a lot more work to set up correctly.
> But anyway, has anyone had success etching their own paste stencils?
> DJ


Someone recently posted PICs about using CNC drilled brass for stencils.  
The holes are of course round but that is not a problem.

How much are you going to do? You know you can just bulk-paste a row of  
pins with a bead over all of them?

ST