Homebrew PCBs

Hi KPL,
       You are using the wrong coating if it cracks. See
Denny's post! I mill circuit boards all the time. The
idea of Scratch and Etch came to me the other day. Mechanical 
Etching bits have a limited life. Using the Scratch and 
Etch method should be faster and cheaper for the home hobbiest.

                                           John   


--- In Homebrew_PCBs@y..., "Karlis" <krahabors@h...> wrote:
> I've been working this way a few times, manually (have no plotter 
yet) using
> some kind of dentist tool, nearly 6000rpm, round-tipped cutter.
> Just coat the board with thin layer of lacquer and "draw" all that 
you need
> with light strokes of the cutter.
> It will make nice, sharp edges, width of insulation path depends on 
cutter.
> 
> If you want only to scratch the lacquer with sharp-tipped tool, the
> insulation paths will be too narrow and the lacquer can crack near 
the
> edges. It will never happen if using rotating tool.
> 
> So the idea is to use fast-spinning tool with round tip, you need 
only to
> push it lightly against the board, so it can be done very quickly 
and
> easily.
> 
> The other technique I have heard of is similar, only the traces 
are "milled"
> when there must be copper not where insulation will be. After that 
the board
> must be tin-plated. Then wash away the lacquer and etch the board 
in some
> kind of solution. Just I don't remember which one of the most 
popular
> etchant solutions doesn't dissolve tin. But it wasn't anything very 
special.
> 
> KPL