Homebrew PCBs

curt_rxr wrote:
> Adam wrote:
>>
>> I was looking at an easier and more reliable way to etch PCBs. I know 
>> from experience that bubble etching never produces acceptable
> uniformity 
>> and often needs manual brushing to finish it off.
>>
> 
> I've found that a simple covered, flat, rocking tank works pretty
> well.  I made mine out of acrylic and use an eccentric on a gear motor
> to make the tank rock about twice a minute.   The flow of the CuCl
> over the board is fairly uniform and my boards seem to etch evenly.
> You need to grip your PCB by two edges and have a deep enough tank to
> allow the etchant to flow over both sides of a double sided PCB.
> 

Interesting. I wonder if this concept could be made to work in a 
vertical tank. The PCB could be mounted to an plastic shaft that is 
attached to some cam assembly at moderate speed. The circular 
displacement might only be several mm , but the agitation could prove to 
be uniform and vigorous. I assume any mechanical method would add a lot 
of complexity, machining up bushes, wheels, brackets, et.


A cover plate is mandatory for bubble agitation since splashes go all 
over the place otherwise. I found the cover plate also needs to have a 
neat fit and recessed slightly so run off goes back into the bulk solution.

Adam