Homebrew PCBs

Earl T. Hackett, Jr. wrote:
> 
> Many years ago we were trying to find ways to strip photoresist from overplated boards.  I stuck a board on the cathode of a plating bath filled with a bit of ammonium chloride.  The current generated a caustic solution at the surface of the board and the generation of hydrogen gas proved very effective at mechanically forcing resist out from under the over plate.  Unfortunately this created quite an explosion hazard so we never commercialized it, but it demonstrated how effective gas generation is at removing materials from a board's surface.



I've never tried electroetching, but I'm curious what the etch 
uniformity is like for a simple (homebrew style) electroetching setup ? 
With a conventional vertical bubble chemical etching tank, I found etch 
uniformity is the most serious factor effecting the minimum trace 
widths. For example, if one area of the PCB is etching twice as fast as 
another area (not uncommon in my experience) then the area with high 
etch rate is over etched by a factor of 2. Fine traces will become too 
thin. This gets worse for thicker copper foils.

Obviously one still needs to keep his/her chemical etching tank, for the 
final removal of copper, but it should be a 2 minute job.

Adam