Homebrew PCBs

----- Original Message ----- 
From: "patroclus04" <patroclus04@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, February 19, 2006 9:15 AM
Subject: [Homebrew_PCBs] Photolithography


> Hello,
> I've been doing some PCBs by "hand" for a year or so.
> Now I would like to use SMD and superficial IC, and I need more
> accuracy and posibility of making several boards.
>
> I tried 4 or 5 times with tonner transfer. Results are not good.
>
> I use magazine paper, I tried 2 o 3 of them. Glossy.
> I print using a LaserJet 6. I iron at high temp, for 10 minutes or
> even more. I wash in warm water, and leave there a few minutes more.
> Then I peel the paper (it takes time and effort, sometimes I just
> damged a track). The pattern is firmly transfered, and it actually
> takes a lot of effort to remove from the copper using disolvent. BUt
> the pattern is heavily damaged. Many track cutted, pads missing,... I
> manage to get some better, but I need very good acuracy for SMD, can't
> just finish by hand...
>
> I don't know what more I can do...
> I'm thinking on going into photographic methods. I was thinking on
> getting photosensitive boards, print a mask, and expose it to UV
> light. Then, as far as I'm concerned, I will have to put in developer,
> and then etch.
>
> Can you guys help me out? any advice??
> Any ideas??

That's the technique I use, it's very easy. You need to buy or make a UV 
exposure unit, easiest way is to buy a couple of 12" UV tubes and 12" 
fluorescent fixtures, swap the tubes and put them in some sort of box with a 
sheet of glass for the PCB and artwork. Shouldn't cost more than 20 GBP.

Leon
--
Leon Heller, G1HSM
leon.heller@...
http://www.geocities.com/leon_heller