Homebrew PCBs

ralucas4277 wrote:

>Coated a section of copper clad pcb with tin/lead solder using 
>soldering iron. Etched a line through the tin/lead solder by spark 
>erosion by hand. Electrode was 1mm copper wire (all this came out of 
>my junk box). Dielectric was diesel fuel (works well but smells).
>
>Continued ablating the tin/lead until the copper showed. Copper is 
>readily visible through the tin. Etched in Ferric Chloride solution. 
>Result is complete etching of the EDM exposed copper.
>
>This demonstrates to me that isolation milling by EDM is possible, 
>and that pcb production by this method is a real possibility.
>
>  
>

  Following this idea, I'd be strongly inclined to forget coating and 
removing, reverse the polarity, and work on point plating the tin to the 
copper..

  Used to use a 12V supply, clip one side to a thin piece of steel, the 
other side onto a pencil lead from a mechanical pencil, and draw fairly 
permanent lines on the steel with the charged lead.  In fact may have to 
try this myself today, just skip the tin and draw lines on copper with 
pencil lead, should be a good enough resist and I'd imagine the copper 
would work ok in place of the steel..

  I should've thought to try this before, I used to do this all the time 
writing things on small scrap steel pieces just because it's fun to see 
the sparking and results..

Alan