Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Well, so...

I bought a handful of 5mm UV LEDs (40) soldered on a bradboard in
groups of 2 LEDs in series because I only had a 7808 voltage regulator
at hand, so every lED on each pair gets 4 volts at 30mA.
I made a 17cm high enclosure with cardboard, lined with aluminum foil
on the inside, I get a fairly even surface of light at the bottom,
although a bit more concentrated at the center.

I wasn't sure it would work after reading how some people are using
powerful UV lights but I gave it a try so I exposed a test PCB for 15
minutes. The film turned a deep purple colour, before it was only
getting to dark blue so I took it as a good omen!

I hadn't actually ironed the film to the board but so again I wasn't
expecting the developing to go well, but I mixed a couple spoons of
Sodium Carbonate (you're right, not calcium carbonate... I know that's
chalk ∗slaps forehead∗) on about half a liter of water, droped the PCB
and just let it seat there while I stirred the water a little. Lo and
behold the unexposed film started to disolve and the cooked lines
remained in place. Perfect!

However I didn't etch the PCB because the traces peeled rather easily.
Obviously a little ironing should fix that.

Now I'm going to try again with the board I wanted to make and see how
does that goes.

Thanks a lot for all the help, I'll update how the PCBs come out.

-Ale