Homebrew PCBs

Markus Zingg wrote:

[deleted]
>The main advantage
> however is independancy and the possibility to have a four layer PCB
> completed within say 2 - 3 hours.... 

Multilayer in 2 - 3 hours !  No offense, but that statement 
made me laugh. Even if you had a fully automated machines 
that did everything from drill to the final dry, it will 
take much longer than 3 hours.
With your experience of the pattern plated through hole, you 
must of learned to appreciate the complex nature of the 
process. As you said earlier its not easy, so unless the 
hobbyist wants convert to PCB making as their primary 
interest then plated through holes will be best left to 
professionals or semi-professionals.

I appreciate your enthusiasm in attempting to make plated 
through hole boards at home. I've always had a interest in 
chemistry and find the inner workings of the PCB process 
quite fascinating. I'm interested in the basic method you 
are using or plan to use. Is it the pattern plating process 
or the "tent and etch" or the "etch back" process ?

In the "etch back" process you take a thin copper clad board 
18 um or less (1/2 oz/ft^2), apply photoresist, expose, 
develop, and copper plate the tracks so an additional 35um+ 
is added. Remove the photoresists and etch the whole board 
until the original 18 um copper cladding is completely 
etched  and so the thicker tracks are not etched. Obviously 
this requires an etching apparatus capable of uniform etch, 
something much better than simple bubble tank.

Adam